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1.	Abay, Simon, 1980, et al. (författare) Quantized Conductance and Its Correlation to the Supercurrent in a Nanowire Connected to Superconductors 2013 Ingår i: Nano Letters. - : American Chemical Society (ACS). - 1530-6992 .- 1530-6984. ; 13:8, s. 3614-3617 Tidskriftsartikel (refereegranskat)abstract We report conductance and supercurrent of InAs nano wires coupled to Al-superconducting electrodes with short channel lengths and good Ohmic contacts. The nanowires are suspended 15 nm above a local gate electrode. The charge density in the nanowires can be controlled by a small change in the gate voltage. For large negative gate voltages, the number of conducting channels is reduced gradually, and we observe a stepwise decrease of both conductance and critical current before the conductance vanishes completely.
2.	Apaydin, Dogukan, 1991, et al. (författare) Optically Pumped UVC Photonic Crystal Surface-Emitting Laser 2023 Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract Photonic crystal surface-emitting lasers (PCSELs) are a new type of semiconductor lasers that offer a high optical output power while maintaining single-mode operation and a low divergence angle. Such devices rely upon the in-plane optical feedback from a two-dimensional photonic crystal and feature out-of-plane emission of the modes with zero group velocity at the photonic band edges by diffraction. Since the demonstration of the first PCSEL [1], the concept has been implemented in standard semiconductor materials with the demonstration of highperforming infrared and blue-emitting lasers [2, 3]. Extending the laser operation to shorter emission wavelengths would be a major breakthrough as such lasers would be of high interest for disinfection, material processing, curing, and medical treatments.
3.	Apaydin, Dogukan, 1991, et al. (författare) UVC photonic crystal surface-emitting lasers with low-divergent far-fields 2023 Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract Photonic crystal surface-emitting lasers (PCSEL) emitting in the ultraviolet (UV) C spectral range are exciting devices due to their low divergence and single-mode emission capable of high output powers as already demonstrated in the infrared [1] and blue spectral range [2]. This is due to their unique design, which incorporates a photonic crystal leading to a large optical gain area. PCSELs are based upon in-plane feedback from the photonic crystal and out-of-plane emission by the diffraction of the modes with zero group velocity at the photonic band edges. We recently demonstrated, to the best of our knowledge, the first UVC PCSEL with an emission at 279 nm. The device structure consists of 3 x 2 nm AlGaN quantum wells (QW) in a 60 nm Al0.70Ga0.30N waveguide and AlN cladding layers. The 140x140 μm large photonic crystal is dry etched into the top AlN cladding layer with a hexagonal lattice consisting of circular holes with a lattice constant of 140 nm and an etch depth of 65 nm, leaving 65 nm between the bottom of the photonic crystals and the first quantum well. Lasing in these PCSELs was achieved by resonant pumping of the QWs by a 266 nm pulsed laser with a spot size of 82 μm at room temperature. The devices exhibit threshold pump power densities from 25 down to 13 MW/cm2 showing a spectral narrowing down to 25 pm. Far-field patterns and band structures were investigated for a range of filling factors (fraction of the surface that is etched) between 10% to 26%, and the far-fields contain emission bands that were not yet reported in PCSELs at longer wavelengths. Changing the filling factor affects the photonic crystal band structure and thereby the optical mode at the Γ-point that will reach threshold first. This feature enables us to intentionally select the lasing mode with the desired far-field pattern. By a proper choice of filling factor, the intensity in the angular emission bands is diminished, resulting in a far-field with a narrow beam divergence of <1°.
4.	Chalangar, Ebrahim, 1984-, et al. (författare) Influence of morphology on electrical and optical properties of graphene/Al-doped ZnO-nanorod composites 2018 Ingår i: Nanotechnology. - Bristol : Institute of Physics Publishing (IOPP). - 0957-4484 .- 1361-6528. ; 29:41 Tidskriftsartikel (refereegranskat)abstract The development of future 3D-printed electronics relies on the access to highly conductive inexpensive materials that are printable at low temperatures (<100 C). The implementation of available materials for these applications are, however, still limited by issues related to cost and printing quality. Here, we report on the simple hydrothermal growth of novel nanocomposites that are well suited for conductive printing applications. The nanocomposites comprise highly Al-doped ZnO nanorods grown on graphene nanoplatelets (GNPs). The ZnO nanorods play the two major roles of (i) preventing GNPs from agglomerating and (ii) promoting electrical conduction paths between the graphene platelets. The effect of two different ZnO-nanorod morphologies with varying Al-doping concentration on the nanocomposite conductivity and the graphenedispersity are investigated. Time-dependent absorption, photoluminescence and photoconductivity measurements show that growth in high pH solutions promotes a better graphene dispersity, higher doping levels and enhanced bonding between the graphene and the ZnO nanorods. Growth in low pH solutions yields samples characterized by a higher conductivity and a reduced number of surface defects. These samples also exhibit a large persistent photoconductivity attributed to an effective charge separation and transfer from the nanorods to the graphene platelets. Our findings can be used to tailor the conductivity of novel printable composites, or for fabrication of large volumes of inexpensive porous conjugated graphene-semiconductor composites. © 2018 IOP Publishing Ltd.
5.	Chalangar, Ebrahim, PhD student, 1984-, et al. (författare) Synthesis of Vertically Aligned ZnO Nanorods Using Sol-gel Seeding and Colloidal Lithography Patterning 2021 Ingår i: Nanoscale Research Letters. - Heidelberg : Springer Science and Business Media LLC. - 1931-7573 .- 1556-276X. ; 16:1 Tidskriftsartikel (refereegranskat)abstract Different ZnO nanostructures can be grown using low-cost chemical bath deposition. Although this technique is cost-efficient and flexible, the final structures are usually randomly oriented and hardly controllable in terms of homogeneity and surface density. In this work, we use colloidal lithography to pattern (100) silicon substrates to fully control the nanorods' morphology and density. Moreover, a sol-gel prepared ZnO seed layer was employed to compensate for the lattice mismatch between the silicon substrate and ZnO nanorods. The results show a successful growth of vertically aligned ZnO nanorods with controllable diameter and density in the designated openings in the patterned resist mask deposited on the seed layer. Our method can be used to fabricate optimized devices where vertically ordered ZnO nanorods of high crystalline quality are crucial for the device performance.
6.	Dabkowska, Aleksandra, et al. (författare) Assembly of RNA nanostructures on supported lipid bilayers. 2015 Ingår i: Nanoscale. - : Royal Society of Chemistry (RSC). - 2040-3372 .- 2040-3364. ; 7:2, s. 583-596 Tidskriftsartikel (refereegranskat)abstract The assembly of nucleic acid nanostructures with controlled size and shape has large impact in the fields of nanotechnology, nanomedicine and synthetic biology. The directed arrangement of nano-structures at interfaces is important for many applications. In spite of this, the use of laterally mobile lipid bilayers to control RNA three-dimensional nanostructure formation on surfaces remains largely unexplored. Here, we direct the self-assembly of RNA building blocks into three-dimensional structures of RNA on fluid lipid bilayers composed of cationic 1,2-dioleoyl-3-trimethylammonium-propane (DOTAP) or mixtures of zwitterionic 1,2-dioleoyl-sn-glycero-3-phosphatidylcholine (DOPC) and cationic sphingosine. We demonstrate the stepwise supramolecular assembly of discrete building blocks through specific and selective RNA-RNA interactions, based on results from quartz crystal microbalance with dissipation (QCM-D), ellipsometry, fluorescence recovery after photobleaching (FRAP) and total internal reflection fluorescence microscopy (TIRF) experiments. The assembly can be controlled to give a densely packed single layer of RNA polyhedrons at the fluid lipid bilayer surface. We show that assembly of the 3D structure can be modulated by sequence specific interactions, surface charge and changes in the salt composition and concentration. In addition, the tertiary structure of the RNA polyhedron can be controllably switched from an extended structure to one that is dense and compact. The versatile approach to building up three-dimensional structures of RNA does not require modification of the surface or the RNA molecules, and can be used as a bottom-up means of nanofabrication of functionalized bio-mimicking surfaces.
7.	Das, Atanu Kumar, et al. (författare) Applications of organic-based nanocomposites in corrosion protection 2023 Ingår i: Nanocomposites-Advanced Materials for Energy and Environmental Aspects. - : Elsevier. - 9780323997041 ; , s. 579-590 Bokkapitel (övrigt vetenskapligt/konstnärligt)abstract Corrosion protection is one of the utmost aims for the reduction of maintenance costs with higher production for the industry. The conventional toxic chromate-based coating is an environmental concern, which has led researchers to develop an organic-based coating with higher anticorrosive performance. The incorporation of nanocomposite increases the adhesion capability of the coating to the metal surface leading to protecting the metal from corrosion. Nanocomposites have novel mechanical and electrochemical properties. The type of nanocomposites depends on the type of nanostructured filler. The performance of nanocomposite coating depends on the types of nanoparticles and additives, the concentration of the dispersed particles, and the mixing processes. In this chapter, nanocellulose-based nanocomposites, their synthesis, and performance against corrosion protection have been discussed. The potential of these nanocomposites as corrosion inhibitors has been pointed out as well.
8.	Das, Atanu Kumar, et al. (författare) Developments of nanocomposites in supercapacitor applications 2023 Ingår i: Nanocomposites-Advanced Materials for Energy and Environmental Aspects. - : Elsevier. - 9780323997041 Bokkapitel (övrigt vetenskapligt/konstnärligt)abstract Energy demand is increasing due to the development of modern society. The use of electronic devices including portable ones is increasing gradually. Thus it is influencing the development of supercapacitors for energy storage due to their 10â€“100 times higher energy storage capacity. At the same time, the implication of biobased material is being considered as environmentally friendly. Cellulose is the most abundant natural renewable biomaterial. Nanocellulose obtained from cellulose possesses special mechanical and electrochemical properties that are being applied for the fabrication of supercapacitors, such as their low-cost and high conductivity and their inexpensive and environment-friendly natures. The development strategy and performance are discussed for better understanding. The work undertaken on improving the fabrication of supercapacitors from cellulose-based nanocomposites will also be summarized.
9.	Das, Atanu Kumar, et al. (författare) Nanocomposites in energy storage applications 2023 Ingår i: Nanocomposites-Advanced Materials for Energy and Environmental Aspects. - : Elsevier BV. - 9780323997041 ; , s. 175-187 Bokkapitel (övrigt vetenskapligt/konstnärligt)abstract The development of energy storage devices for the growing energy demand is a prerequisite for modern society. Specific characteristics, i.e., thermal, electrochemical, and mechanical properties, of nanocomposites are essential for their application in energy storage appliances. Biobased nanocomposites are being considered environmentally friendly. Nanocellulose, lignin, and chitosan are obtained from an abundant source of natural renewable materials. Using them in developing batteries and supercapacitors has great potential for a sustainable supply of energy. Nanocellulose and the lignin-based electrode have shown excellent electrochemical properties for application in a battery. Nanocellulose, lignin, and chitosan-based electrode have also exhibited excellent electrochemical properties for their utilization in supercapacitors. In addition, their low-cost, high conductivity, and environment-friendly nature are being considered for the preparation of energy storage devices. In this chapter, the development strategy and performance of batteries and supercapacitors obtained from biobased nanocomposites have been discussed.
10.	Das, Atanu Kumar, et al. (författare) Natural Fiber-based Nanocomposites as Corrosion Inhibitors 2022 Ingår i: Anticorrosive Nanomaterials. - Cambridge : Royal Society of Chemistry (RSC). ; :56, s. 191-206 Bokkapitel (övrigt vetenskapligt/konstnärligt)abstract Corrosion constitutes one of the troublesome issues in different industries,Â i.e., automotive, marine, construction, oil and gas. Protection from corrosion aims at reducing maintenance costs with higher production for the industry. Due to high toxicity, chromate-based coatings remain an environmental concern. This has necessitated the development of an organic-based coating with higher anti-corrosive performance. The adhesion capability of coating on metal surfaces can be improved through the incorporation of nanocomposites, which in turn can protect the metal from corrosion. Owing to their novel mechanical and electrochemical properties, types of nanocomposites dictate the types of nanostructured filler. The inclusion of cellulose nanocrystal (CNC) in epoxy-Zn rich coating shows better anti-corrosive performance for mild steel. In addition, silver nanoparticles and chitosan-based nanocomposite coating can protect mild steel from corrosion. However, the performance of the nanocomposite coating depends on the types of nanoparticles and additives, the concentration of the dispersed particles and mixing processes. In this chapter, the use of natural fiber-based nanocomposites in corrosion protection, and their synthesis and performance have been discussed. Alongside this, the potential of natural fiber-based nanocomposites for corrosion protection has been pointed out.
11.	Hussain, Laiq, et al. (författare) Defect-induced infrared electroluminescence from radial GaInP/AlGaInP quantum well nanowire array light- emitting diodes 2017 Ingår i: Nanotechnology. - Bristol : IOP Publishing. - 0957-4484 .- 1361-6528. ; 28:48 Tidskriftsartikel (refereegranskat)abstract Radial GaInP/AlGaInP nanowire array light-emitting diodes (LEDs) are promising candidates for novel high-efficiency solid state lighting due to their potentially large strain-free active emission volumes compared to planar LEDs. Moreover, by proper tuning of the diameter of the nanowires, the fraction of emitted light extracted can be significantly enhanced compared to that of planar LEDs. Reports so far on radial growth of nanowire LED structures, however, still point to significant challenges related to obtaining defect-free radial heterostructures. In this work, we present evidence of optically active growth-induced defects in a fairly broad energy range in vertically processed radial GaInP/AlGaInP quantum well nanowire array LEDs using a variety of complementary experimental techniques. In particular, we demonstrate strong infrared electroluminescence in a spectral range centred around 1 eV (1.2 μm) in addition to the expected red light emission from the quantum well. Spatially resolved cathodoluminescence studies reveal a patchy red light emission with clear spectral features along the NWs, most likely induced by variations in QW thickness, composition and barriers. Dark areas are attributed to infrared emission generated by competing defect-assisted radiative transitions, or to trapping mechanisms involving non-radiative recombination processes. Possible origins of the defects are discussed.
12.	Jafari Jam, R., et al. (författare) Embedded sacrificial AlAs segments in GaAs nanowires for substrate reuse 2020 Ingår i: Nanotechnology. - Bristol : Institute of Physics Publishing (IOPP). - 0957-4484 .- 1361-6528. ; 31:20 Tidskriftsartikel (refereegranskat)abstract We report on the use of a sacrificial AlAs segment to enable substrate reuse for nanowire synthesis. A silicon nitride template was deposited on a p-type GaAs substrate. Then a pattern was transferred to the substrate by nanoimprint lithography and reactive ion etching. Thermal evaporation was used to define Au seed particles. Metalorganic vapour phase epitaxy was used to grow AlAs-GaAs NWs in the vapour-liquid-solid growth mode. The yield of synthesised nanowires, compared to the number expected from the patterned template, was more than 80%. After growth, the nanowires were embedded in a polymer and mechanically removed from the parent substrate. The parent substrate was then immersed in an HCl:H2O (1:1) mixture to dissolve the remaining stub of the sacrificial AlAs segment. The pattern fidelity was preserved after peeling off the nanowires and cleaning, and the semiconductor surface was flat and ready for reuse. Au seed particles were then deposited on the substrate by use of pulse electrodeposition, which was selective to the openings in the growth template, and then nanowires were regrown. The yield of regrowth was less optimal compared to the first growth but the pattern was preserved. Our results show a promising approach to reduce the final cost of III-V nanowire based solar cells. © 2020 The Author(s). Published by IOP Publishing Ltd.
13.	Jeffet, Jonathan, et al. (författare) Super-Resolution Genome Mapping in Silicon Nanochannels 2016 Ingår i: ACS Nano. - : American Chemical Society (ACS). - 1936-0851 .- 1936-086X. ; 10:11, s. 9823-9830 Tidskriftsartikel (refereegranskat)abstract Optical genome mapping in nanochannels is a powerful genetic analysis method, complementary to deoxyribonucleic acid (DNA) sequencing. The method is based on detecting a pattern of fluorescent labels attached along individual DNA molecules. When such molecules are extended in nanochannels, the labels create a fluorescent genetic barcode that is used for mapping the DNA molecule to its genomic locus and identifying large-scale variation from the genome reference. Mapping resolution is currently limited by two main factors: the optical diffraction limit and the thermal fluctuations of DNA molecules suspended in the nanochannels. Here, we utilize single-molecule tracking and super-resolution localization in order to improve the mapping accuracy and resolving power of this genome mapping technique and achieve a 15-fold increase in resolving power compared to currently practiced methods. We took advantage of a naturally occurring genetic repeat array and labeled each repeat with custom-designed Trolox conjugated fluorophores for enhanced photostability. This model system allowed us to acquire extremely long image sequences of the equally spaced fluorescent markers along DNA molecules, enabling detailed characterization of nanoconfined DNA dynamics and quantitative comparison to the Odijk theory for confined polymer chains. We present a simple method to overcome the thermal fluctuations in the nanochannels and exploit single-step photobleaching to resolve subdiffraction spaced fluorescent markers along fluctuating DNA molecules with ∼100 bp resolution. In addition, we show how time-averaging over just ∼50 frames of 40 ms enhances mapping accuracy, improves mapping P-value scores by 3 orders of magnitude compared to nonaveraged alignment, and provides a significant advantage for analyzing structural variations between DNA molecules with similar sequence composition.
14.	Nowakowska, Sylwia, et al. (författare) Adsorbate-Induced Modification of the Confining Barriers in a Quantum Box Array 2018 Ingår i: ACS Nano. - : American Chemical Society (ACS). - 1936-0851 .- 1936-086X. ; 12:1, s. 768-778 Tidskriftsartikel (refereegranskat)abstract Quantum devices depend on addressable elements, which can be modified separately and in their mutual interaction. Self-assembly at surfaces, for example, formation of a porous (metal-) organic network, provides an ideal way to manufacture arrays of identical quantum boxes, arising in this case from the confinement of the electronic (Shockley) surface state within the pores. We show that the electronic quantum box state as well as the interbox coupling can be modified locally to a varying extent by a selective choice of adsorbates, here C60, interacting with the barrier. In view of the wealth of differently acting adsorbates, this approach allows for engineering quantum states in on-surface network architectures.
15.	Palmqvist, Martin, et al. (författare) Maghemite Nanoparticles Acts as Nanozymes, Improving Growth and Abiotic Stress Tolerance in Brassica napus 2017 Ingår i: Nanoscale Research Letters. - : Springer Science and Business Media LLC. - 1931-7573 .- 1556-276X. ; 12 Tidskriftsartikel (refereegranskat)abstract Yttrium doping-stabilized γ-Fe2O3 nanoparticles were studied for its potential to serve as a plant fertilizer and, through enzymatic activity, support drought stress management. Levels of both hydrogen peroxide and lipid peroxidation, after drought, were reduced when γ-Fe2O3 nanoparticles were delivered by irrigation in a nutrient solution to Brassica napus plants grown in soil. Hydrogen peroxide was reduced from 151 to 83 μM g−1 compared to control, and the malondialdehyde formation was reduced from 36 to 26 mM g−1. Growth rate of leaves was enhanced from 33 to 50% growth compared to fully fertilized plants and SPAD-measurements of chlorophyll increased from 47 to 52 suggesting improved agronomic properties by use of γ-Fe2O3 nanoparticles as fertilizer as compared to chelated iron.
16.	Palo-Nieto, Carlos, 1985-, et al. (författare) Functionalization of cellulose nanofibrils to develop novel ROS-sensitive biomaterials 2023 Ingår i: Materials Advances. - : Royal Society of Chemistry. - 2633-5409. ; 4:6, s. 1555-1565 Tidskriftsartikel (refereegranskat)abstract Wood derived cellulose nanofibrils (CNFs) have emerged as an interesting material for biomedical applications. Functionalization of the nanofibrils with bioactive molecules is a potent tool to tailor CNF materials for specific applications in biomedicine. The present work proposes the functionalization of CNFs with a reactive oxygen species (ROS)-sensitive oligopeptide to develop a novel CNF-based material for the treatment of medical conditions associated with high levels of ROS such as chronic wounds. Oligoproline peptides of two different lengths (5 and 10 proline units) were covalently incorporated onto the CNF surface, several water-based chemical approaches were explored and the reaction conditions to maximize peptide substitution and the degree of fibre crosslinking were optimized. The chemical structure, degree of peptide substitution, degree of fibre crosslinking, surface morphology and ROS-sensitivity of the oligoproline–CNF materials were characterized. Double-crosslinked CNF hydrogels (Ca2+–oligoproline–CNF) were further prepared and the ability of the hydrogels to protect cells from an oxidative environment was investigated in vitro with human dermal fibroblasts, as a first evaluation of the potential of the novel CNF material to be used in chronic wound therapies. Optimization of the reaction conditions resulted in a degree of peptide substitution of 102 ± 10 μmol g−1 CNF irrespective of the oligoproline length and a degree of crosslinking of 55–80% depending on the number of proline units. The results showed that the oligoproline covalently attached to CNFs via carbodiimide chemistry maintained its ability to respond to ROS and that the responsiveness in terms of viscoelastic properties depended on the length of the oligopeptide, with the hydrogel being more responsive when functionalized with 10 proline units compared with 5 proline units. Furthermore, the double crosslinked Ca2+–oligoproline–CNF hydrogels promoted the survival of human dermal fibroblasts exposed to high levels of ROS. This study is the first one to provide an insight into the development of ROS-sensitive materials based on CNFs and opens up possibilities for further investigation on the use of these novel materials in chronic wound care.
17.	Sedrpooshan, Mehran, et al. (författare) Template-free generation and integration of functional 1D magnetic nanostructures 2023 Ingår i: Nanoscale. - : Royal Society of Chemistry. - 2040-3372 .- 2040-3364. Tidskriftsartikel (refereegranskat)abstract The direct integration of 1D magnetic nanostructures into electronic circuits is crucial for realizing their great potential as components in magnetic storage, logical devices, and spintronic applications. Here, we present a novel template-free technique for producing magnetic nanochains and nanowires using directed self-assembly of gas-phase-generated metallic nanoparticles. The 1D nanostructures can be self-assembled along most substrate surfaces and can be freely suspended over micrometer distances, allowing for direct incorporation into different device architectures. The latter is demonstrated by a one-step integration of nanochains onto a pre-patterned Si chip and the fabrication of devices exhibiting magnetoresistance. Moreover, fusing the nanochains into nanowires by post-annealing significantly enhances the magnetic properties, with a 35% increase in the coercivity. Using magnetometry, X-ray microscopy, and micromagnetic simulations, we demonstrate how variations in the orientation of the magnetocrystalline anisotropy and the presence of larger multi-domain particles along the nanochains play a key role in the domain formation and magnetization reversal. Furthermore, it is shown that the increased coercivity in the nanowires can be attributed to the formation of a uniform magnetocrystalline anisotropy along the wires and the onset of exchange interactions.
18.	Sepehri, Sobhan, 1986, et al. (författare) Volume-amplified magnetic bioassay integrated with microfluidic sample handling and high-Tc SQUID magnetic readout 2018 Ingår i: APL Bioengineering. - : AIP Publishing. - 2473-2877. ; 2:1 Tidskriftsartikel (refereegranskat)abstract A bioassay based on a high-Tc superconducting quantum interference device (SQUID) reading out functionalized magnetic nanoparticles (fMNPs) in a prototype microfluidic platform is presented. The target molecule recognition is based on volume amplification using padlock-probe-ligation followed by rolling circle amplification (RCA). The MNPs are functionalized with single-stranded oligonucleotides, which give a specific binding of the MNPs to the large RCA coil product, resulting in a large change in the amplitude of the imaginary part of the ac magnetic susceptibility. The RCA products from amplification of synthetic Vibrio cholera target DNA were investigated using our SQUID ac susceptibility system in microfluidic channel with an equivalent sample volume of 3 μl. From extrapolation of the linear dependence of the SQUID signal versus concentration of the RCA coils, it is found that the projected limit of detection for our system is about 1.0 e5 RCA coils (0.2e−18 mol), which is equivalent to 66 fM in the 3 μl sample volume. This ultra-high magnetic sensitivity and integration with microfluidic sample handling are critical steps towards magnetic bioassays for rapid detection of DNA and RNA targets at the point of care.
19.	Sun, Rui, et al. (författare) Highly Porous Amorphous Calcium Phosphate for Drug Delivery and Bio-Medical Applications 2020 Ingår i: Nanomaterials. - : MDPI. - 2079-4991. ; 10:1 Tidskriftsartikel (refereegranskat)abstract Amorphous calcium phosphate (ACP) has shown significant effects on the biomineralization and promising applications in bio-medicine. However, the limited stability and porosity of ACP material restrict its practical applications. A storage stable highly porous ACP with Brunauer–Emmett–Teller surface area of over 400 m2/g was synthesized by introducing phosphoric acid to a methanol suspension containing amorphous calcium carbonate nanoparticles. Electron microscopy revealed that the porous ACP was constructed with aggregated ACP nanoparticles with dimensions of several nanometers. Large angle X-ray scattering revealed a short-range atomic order of <20 Å in the ACP nanoparticles. The synthesized ACP demonstrated long-term stability and did not crystallize even after storage for over 14 months in air. The stability of the ACP in water and an α-MEM cell culture medium were also examined. The stability of ACP could be tuned by adjusting its chemical composition. The ACP synthesized in this work was cytocompatible and acted as drug carriers for the bisphosphonate drug alendronate (AL) in vitro. AL-loaded ACP released 25% of the loaded AL in the first 22 days. These properties make ACP a promising candidate material for potential application in biomedical fields such as drug delivery and bone healing.
20.	Surendiran, Pradheebha, et al. (författare) Solving Exact Cover Instances with Molecular-Motor-Powered Network-Based Biocomputation 2022 Ingår i: ACS Nanoscience Au. - : American Chemical Society (ACS). - 2694-2496 .- 2694-2496. Tidskriftsartikel (refereegranskat)abstract Information processing by traditional, serial electronic processors consumes an ever-increasing part of the global electricity supply. An alternative, highly energy efficient, parallel computing paradigm is network-based biocomputation (NBC). In NBC a given combinatorial problem is encoded into a nanofabricated, modular network. Parallel exploration of the network by a very large number of independent molecular-motor-propelled protein filaments solves the encoded problem. Here we demonstrate a significant scale-up of this technology by solving four instances of Exact Cover, a nondeterministic polynomial time (NP) complete problem with applications in resource scheduling. The difficulty of the largest instances solved here is 128 times greater in comparison to the current state of the art for NBC.
21.	Suyatin, Dmitry, et al. (författare) Strong Schottky barrier reduction at Au-catalyst/GaAs-nanowire interfaces by electric dipole formation and Fermi-level unpinning 2014 Ingår i: Nature Communications. - London : Springer Science and Business Media LLC. - 2041-1723. ; 5 Tidskriftsartikel (refereegranskat)abstract Nanoscale contacts between metals and semiconductors are critical for further downscaling of electronic and optoelectronic devices. However, realizing nanocontacts poses significant challenges since conventional approaches to achieve ohmic contacts through Schottky barrier suppression are often inadequate. Here we report the realization and characterization of low n-type Schottky barriers (~0.35 eV) formed at epitaxial contacts between Au-In alloy catalytic particles and GaAs-nanowires. In comparison to previous studies, our detailed characterization, employing selective electrical contacts defined by high-precision electron beam lithography, reveals the barrier to occur directly and solely at the abrupt interface between the catalyst and nanowire. We attribute this lowest-to-date-reported Schottky barrier to a reduced density of pinning states (~1017 m−2) and the formation of an electric dipole layer at the epitaxial contacts. The insight into the physical mechanisms behind the observed low-energy Schottky barrier may guide future efforts to engineer abrupt nanoscale electrical contacts with tailored electrical properties.
22.	Träger, Andrea, et al. (författare) Strong and tuneable wet adhesion with rationally designed layer-by-layer assembled triblock copolymer films 2016 Ingår i: Nanoscale. - : Royal Society of Chemistry. - 2040-3364 .- 2040-3372. ; 8:42, s. 18204-18211 Tidskriftsartikel (refereegranskat)abstract this study the wet adhesion between Layer-by-Layer (LbL) assembled films of triblock copolymer micelles was investigated. Through the LbL assembly of triblock copolymer micelles with hydrophobic, low glass transition temperature (T-g) middle blocks and ionic outer blocks, a network of energy dissipating polymer chains with electrostatic interactions serving as crosslinks can be built. Four triblock copolymers were synthesized through Atom Transfer Radical Polymerisation (ATRP). One pair had a poly(2-ethyl-hexyl methacrylate) middle block with cationic or anionic outer blocks. The other pair contained the same ionic outer blocks but poly(n-butyl methacrylate) as the middle block. The wet adhesion was evaluated with colloidal probe AFM. To our knowledge, wet adhesion of the magnitude measured in this study has not previously been measured on any polymer system with this technique. We are convinced that this type of block copolymer system grants the ability to control the geometry and adhesive strength in a number of nano-and macroscale applications.
23.	Wetterskog, Erik, et al. (författare) Size and property bimodality in magnetic nanoparticle dispersions : single domain particles vs. strongly coupled nanoclusters 2017 Ingår i: Nanoscale. - : ROYAL SOC CHEMISTRY. - 2040-3364 .- 2040-3372. ; 9:12, s. 4227-4235 Tidskriftsartikel (refereegranskat)abstract The widespread use of magnetic nanoparticles in the biotechnical sector puts new demands on fast and quantitative characterization techniques for nanoparticle dispersions. In this work, we report the use of asymmetric flow field-flow fractionation (AF4) and ferromagnetic resonance (FMR) to study the properties of a commercial magnetic nanoparticle dispersion. We demonstrate the effectiveness of both techniques when subjected to a dispersion with a bimodal size/magnetic property distribution: i.e., a small superparamagnetic fraction, and a larger blocked fraction of strongly coupled colloidal nanoclusters. We show that the oriented attachment of primary nanocrystals into colloidal nanoclusters drastically alters their static, dynamic, and magnetic resonance properties. Finally, we show how the FMR spectra are influenced by dynamical effects; agglomeration of the superparamagnetic fraction leads to reversible line-broadening; rotational alignment of the suspended nanoclusters results in shape-dependent resonance shifts. The AF4 and FMR measurements described herein are fast and simple, and therefore suitable for quality control procedures in commercial production of magnetic nanoparticles.
24.	Abay, Simon, 1980, et al. (författare) High Critical-Current Superconductor-InAs Nanowire-Superconductor Junctions 2012 Ingår i: Nano Letters. - : American Chemical Society (ACS). - 1530-6992 .- 1530-6984. ; 12:11, s. 5622-5625 Tidskriftsartikel (refereegranskat)abstract We report on the fabrication of InAs nanowires coupled to superconducting leads with high critical current and widely tunable conductance. We implemented a double lift off nanofabrication Method to get very short nanowire devices with Ohmic contacts. We observe very high critical. currents of up to 800 nA in a wire with a diameter of 80 nm. The current- voltage characteristics of longer and suspended nanowires display,either. Coulomb blockade or supercurrent depending on a local gate voltage, combining different regimes of transport in a single device.
25.	Abbondanza, Giuseppe, 1991, et al. (författare) Au-Pd Barcode Nanowires with Tailored Lattice Parameters and Segment Lengths for Catalytic Applications 2024 Ingår i: ACS Applied Nano Materials. - 2574-0970. ; 7:4, s. 3861-3874 Tidskriftsartikel (refereegranskat)abstract In this study, we present a systematic investigation of the controlled fabrication of Au-Pd barcode nanowires within nanoporous anodic aluminum oxide (NP-AAO) templates. By using a combination of in situ X-ray diffraction (XRD), focused ion beam scanning electron microscopy (FIB-SEM), and transmission electron microscopy (TEM), we elucidate the influence of template preparation methods on the resulting nanowire properties. The template treatment, involving either pore widening or barrier layer thinning, significantly impacts nanowire growth. Through the analysis of the XRD data, we observe sequential deposition of Au and Pd segments with lattice parameter variations and strain effects. Particularly, the lattice parameters of Au and Pd segments display intricate temporal dependencies, influenced by interfacial effects and strain caused by growth under confinement. FIB-SEM imaging reveals uniform and reproducible nanowire lengths in the template treated with pore widening. Furthermore, TEM analysis confirms the presence of distinct Au and Pd segments, while scanning TEM-energy-dispersive X-ray spectroscopy revealed minor evidence of interdiffusion between the first and the second electrodeposited segments. Our findings emphasize the potential of the electrodeposition process within nanoporous templates for producing barcode nanowires with precise segmental properties. The combination of in situ XRD and electron microscopy offers valuable insights into the growth dynamics and structural characteristics of the fabricated Au-Pd barcode nanowires. This controlled fabrication strategy opens doors to tailoring nanowire properties for diverse applications, particularly in catalysis.
26.	Abbondanza, Giuseppe (författare) Ordered arrays of low-dimensional Au and Pd : synthesis and in situ observations 2022 Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract Electrodeposition of metals in templates of nano-porous anodic aluminum oxide (NP-AAO) is a versatile way of fabricating ordered arrays of metal nanowires. Thanks to the self-arranged long-range hexagonal order of the pores, electrodeposition in NP-AAO is an easily scalable bottom-up synthesis route and an attractive alternative to traditional top-down fabrication methods such as electron beam lithography.Since NP-AAO is a non-conductive medium and since it is potentially soluble in non-neutral pH solutions, the electrodeposition of metals in NP-AAO represents a challenge. These aspects are discussed in this thesis, aiming to establish a reproducible and reliable protocol for the electrodeposition of Au and Pd.By using ex situ x-ray diffraction, it has been found that the growth of Au and Pd in the confined environment of nano-pores leads (i) to a deformation of the crystalline structure, as the lattice constant is smaller along the nanowire radius and larger along the nanowire axis, compared to the bulk lattice constant, and (ii) to a crystallite size anisotropy: it is limited by the pore radius in the horizontal direction and it is larger in the direction of growth.The electrochemical growth of Au and Pd nanowires was followed in situ by x-ray scattering methods. In the case of Au nanowires, the time-resolved measurements revealed that the anisotropy of the lattice parameter progresses as a function of time, which suggests that the strain state of the nanomaterials can be artificially selected. This findings might be beneficial in the strain-engineering of Au nanoelectrode arrays for electrocatalysis. In the case of Pd nanowires, the measurements revealed strain variations, as well as phase transitions attributed to the existence of alpha- and beta-phase Pd hydride in the NP-AAO template, due to the exposure of Pd to hydrogen evolved at the working electrode. These findings suggest that Pd in NP-AAO has potential applications in the design of hydrogen storage devices.
27.	Abdel, Naseem, et al. (författare) Fabrication and Characterization of Ultra-Thin PIN Silicon Detectors for Counting the Passage of MeV Ions 2013 Ingår i: IEEE Transactions on Nuclear Science. - 0018-9499. ; 60:2, s. 1182-1188 Tidskriftsartikel (refereegranskat)abstract This paper describes the fabrication and initial characterization of an ultra-thin silicon PIN detector using a new technique in silicon nanotechnology. In collaboration with the Nuclear Physics Division and the Lund Nano Lab at Lund University, we have developed and manufactured ultra thin Delta E-detectors for spectroscopic applications. The fabrication process has been carried out using a double-polished silicon substrate n-type wafer and locally thinning by means of a 10:1 solution of 25% tetramethyl ammonium hydroxide (TMAH) with Isopropyl alcohol. More than 100 detectors of different thicknesses, down to 5 mu m with active areas ranging from 0.71 to 0.172 mm(2), have been fabricated. The main design considerations of our thin detectors were a very low leakage current below 12 nA and a low full depletion voltage at a reverse bias less than 1.5 V. Finally, most of our thin detectors offer an energy resolution (FWHM) as low as 31 keV for 5.487 MeV alpha particles from a Am-241 source.
28.	Abdel, N. S., et al. (författare) Efficient ultra-thin transmission silicon detectors for a single-ion irradiation system at the Lund Ion Beam Analysis Facility 2014 Ingår i: Journal of Instrumentation. - 1748-0221. ; 9 Tidskriftsartikel (refereegranskat)abstract This paper describes the fabrication of efficient ultra-thin silicon transmission detectors for use as pre-cell detectors in single-ion experiments on living cells at the Lund Ion Beam Analysis Facility. More than 40 detectors of different thicknesses down to 5 mu m have been fabricated and packaged. The main design considerations were very low leakage current (below 9 nA) and low full depletion voltage at biases less than 0.5 V at room temperature. In addition, we have shown that cooling the device can reduce the leakage current to 3 nA. The experimental testing of the pre-cell detection system is based on counting the passage of ions through the transmission (Delta E) detector before hitting the stopping (E) detector placed behind it, to ensure the accurate delivery of specific doses of radiation to the sample. Optimal detection of the fabricated detectors for the passage of an external beam of 2.2 MeV protons was obtained by cooling the device to below 2 degrees C. Cooling the Delta E detectors provides up to 20% better energy resolution and up to 98% detection efficiency for 2.2 MeV protons. The development of this kind of efficient pre-cell detector enables a range of new experiments to be conducted on thick biological samples.
29.	Adham, Kristi (författare) Growth and Characterization of Core-Branch Nanowire Structures 2022 Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract This thesis investigates growth of III – V semiconductor nanowire (NW) arrays, in a core- branch architecture, with the aim to develop diffusion driven light emitting diodes (LED) on NWs. Diffusion driven LEDs are based on the concept of decoupling the active region from the p-n junction. The carriers are injected by diffusion in the active region, because of the bandgap difference between the pn junction and the active region. This concept can be used in NW structures where tree structures are grown with high bandgap cores and low bandgap branches. The small diameter of the branches facilitates light extraction and removes the limitation of total internal reflection. The first part of the thesis focuses on studying the deposition parameters of Au particles on the sidewalls of the core NWs. These particles act as catalysts for branch growth. The second part of the thesis focuses on the growth of branches from homostructures (InP-InP) and heterostructures (InGaP-InGaP) where the Ga content in the core is higher than in the branches. We demonstrate high density branch growth distributed along the entire core length. Finally, we present some results from photoluminescence measurements in heterostructure core-branch NWs. The results presented in this thesis are intended to contribute to the development of a new and promising LED architecture.
30.	Adham, Kristi, et al. (författare) Growth of branched nanowires via solution-based Au seed particle deposition 2023 Ingår i: Materials Research Express. - 2053-1591. ; 10:8 Tidskriftsartikel (refereegranskat)abstract Nanowires offer unprecedented flexibility as nanoscale building blocks for future optoelectronic devices, especially with respect to nanowire solar cells and light-emitting diodes. A relatively new concept is that of charge carrier diffusion-induced light-emitting diodes, for which nanowires offer an interesting architecture by use of particle-assisted core-branch growth. The branches should be homogenously distributed along the cores. However, most deposition techniques, such as aerosol particle deposition, mainly yield particles at the nanowire tips for dense nanowire arrays. In this study, we demonstrate a liquid-based approach for homogeneously distributed formation of catalytic Au particles on the core nanowire sidewalls which is cost and time-efficient. Subsequently, we demonstrate the synthesis of dispersed nanowire branches. We show that by changing the deposition parameters, we can tune the number of branches, their dimensions, and their growth direction.
31.	Adolfsson, Karl, et al. (författare) Fluorescent Nanowire Heterostructures as a Versatile Tool for Biology Applications 2013 Ingår i: Nano Letters. - : American Chemical Society (ACS). - 1530-6992 .- 1530-6984. ; 13:10, s. 4728-4732 Tidskriftsartikel (refereegranskat)abstract Nanowires are increasingly used in biology, as sensors, as injection devices, and us model systems for toxicity studies. Currently, in situ visualization of nanowires in biological media is done using organic dyes, which a;:e prone to photobleaching, or using microscopy methods which either yield poor resolution or require a sophisticated setup. Here we show that inherently fluorescent nanowire axial heterostructnies c:an be used to localize and identify nanowires in cells and tissue; By synthesizing GaP GaInP nanowire heterostructures, with nonfluorescent GaP segments and fluorescent GaInP segments, we created a barcode labeling system enabling the distinction of the nanowire morphological and chemical properties using fluorescence microscopy. The GaInP photoluminescence stability, combined with the fact that the nanowires can be coated with different materials while retaining their fluorescence, make these nanowires promising tools for biological and nanotoxicological studies.
32.	Adolfsson, Karl (författare) GaP and GaInP nanowires as model particles for in vivo fiber toxicity studies 2017 Doktorsavhandling (övrigt vetenskapligt/konstnärligt)
33.	Adolfsson, Karl, et al. (författare) Ingestion of gallium phosphide nanowires has no adverse effect on Drosophila tissue function. 2013 Ingår i: Nanotechnology. - : IOP Publishing. - 0957-4484 .- 1361-6528. ; 24:28 Tidskriftsartikel (refereegranskat)abstract Engineered nanoparticles have been under increasing scrutiny in recent years. High aspect ratio nanoparticles such as carbon nanotubes and nanowires have raised safety concerns due to their geometrical similarity to asbestos fibers. III-V epitaxial semiconductor nanowires are expected to be utilized in devices such as LEDs and solar cells and will thus be available to the public. In addition, clean-room staff fabricating and characterizing the nanowires are at risk of exposure, emphasizing the importance of investigating their possible toxicity. Here we investigated the effects of gallium phosphide nanowires on the fruit fly Drosophila melanogaster. Drosophila larvae and/or adults were exposed to gallium phosphide nanowires by ingestion with food. The toxicity and tissue interaction of the nanowires was evaluated by investigating tissue distribution, activation of immune response, genome-wide gene expression, life span, fecundity and somatic mutation rates. Our results show that gallium phosphide nanowires applied through the diet are not taken up into Drosophila tissues, do not elicit a measurable immune response or changes in genome-wide gene expression and do not significantly affect life span or somatic mutation rate.
34.	Agback, Peter, et al. (författare) Site-specific recognition of SARS-CoV-2 nsp1 protein with a tailored titanium dioxide nanoparticle - elucidation of the complex structure using NMR data and theoretical calculation 2022 Ingår i: Nanoscale advances. - : Royal Society of Chemistry (RSC). - 2516-0230. ; 4, s. 1527-1532 Tidskriftsartikel (refereegranskat)abstract The ongoing world-wide Severe Acute Respiratory Syndrome coronavirus 2 (SARS-CoV-2) pandemic shows the need for new potential sensing and therapeutic means against the CoV viruses. The SARS-CoV-2 nsp1 protein is important, both for replication and pathogenesis, making it an attractive target for intervention. In this study we investigated the interaction of this protein with two types of titania nanoparticles by NMR and discovered that while lactate capped particles essentially did not interact with the protein chain, the aminoalcohol-capped ones showed strong complexation with a distinct part of an ordered alpha-helix fragment. The structure of the forming complex was elucidated based on NMR data and theoretical calculation. To the best of our knowledge, this is the first time that a tailored titanium oxide nanoparticle was shown to interact specifically with a unique site of the full-length SARS-CoV-2 nsp1 protein, possibly interfering with its functionality.
35.	Aghaeipour, Mahtab, et al. (författare) Considering symmetry properties of inp nanowire/light incidence systems to gain broadband absorption 2017 Ingår i: IEEE Photonics Journal. - Piscataway : IEEE. - 1943-0655. ; 9:3 Tidskriftsartikel (refereegranskat)abstract Geometrically designed III-V nanowire arrays are promising candidates for disruptive optoelectronics due to the possibility of obtaining a strongly enhanced absorption resulting from nanophotonic resonance effects. With normally incident light on such vertical nanowire arrays, the absorption spectra exhibit peaks that originate from excitation of HE1m waveguide modes in the constituent nanowires. However, the absorption spectra typically show dips between the absorption peaks. Conventionally, such weak absorption has been counteracted by either making the nanowires longer or by decreasing the pitch of the array, both alternatives effectively increasing the volume of absorbing material in the array. Here, we first study two approaches for compensating the absorption dips by exciting additional Mie resonances: 1) oblique light incidence on vertical InP nanowire arrays and 2) normal light incidence on inclined InP nanowire arrays. We then show that branched nanowires offer a novel route to achieve broadband absorption by taking advantage of simultaneous excitations of Mie resonances in the branches and guided HE1m modes in the stem. Finite element method calculations show that the absorption efficiency is enhanced from 0.72 for vertical nanowires to 0.78 for branched nanowires under normal light incidence. Our work provides new insight for the development of novel efficient photovoltaics with high efficiency and reduced active material volume.
36.	Aghaeipour, Mahtab, et al. (författare) Enhanced broadband absorption in nanowire arrays with integrated Bragg reflectors 2018 Ingår i: Nanophotonics. - Berlin : Walter de Gruyter GmbH. - 2192-8614. ; 7:5, s. 819-825 Tidskriftsartikel (refereegranskat)abstract A near-unity unselective absorption spectrum is desirable for high-performance photovoltaics. Nanowire (NW) arrays are promising candidates for efficient solar cells due to nanophotonic absorption resonances in the solar spectrum. The absorption spectra, however, display undesired dips between the resonance peaks. To achieve improved unselective broadband absorption, we propose to enclose distributed Bragg reflectors (DBRs) in the bottom and top parts of indium phosphide (InP) NWs, respectively. We theoretically show that by enclosing only two periods of In0.56Ga0.44As/InP DBRs, an unselective 78% absorption efficiency (72% for NWs without DBRs) is obtained at normal incidence in the spectral range from 300 nm to 920 nm. Under oblique light incidence, the absorption efficiency is enhanced up to about 85% at an incidence angle of 50°. By increasing the number of DBR periods from two to five, the absorption efficiency is further enhanced up to 95% at normal incidence. In this work, we calculated optical spectra for InP NWs, but the results are expected to be valid for other direct band gap III-V semiconductor materials. We believe that our proposed idea of integrating DBRs in NWs offers great potential for high-performance photovoltaic applications.
37.	Aghaeipour, Mahtab, et al. (författare) Enhanced optical absorption in nanowires over a desire range of wavelengths 2017 Ingår i: MOC2017 : technical digest of the Twenty-Second Microoptics Conference. - : IEEE. - 9784863486096 - 9781509049240 ; , s. 360-361 Konferensbidrag (refereegranskat)abstract Engineering optical absorption in nanowires, over a desire range of wavelengths is of importance to design high-performance nanowire-based photovoltaics. To this end, we integrate the nanowires with distributed Bragg reflectors to enhance absorption spectra of the nanowires and relate the consequent enhancement to increasing the optical path lengths of the modes. © 2017 The Japan Society of Applied Physics.
38.	Aghaeipour, Mahtab (författare) Tailoring the Optical Response of III-V Nanowire Arrays 2017 Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract Semiconductor nanowires show a great deal of promise for applications in a wide range of important fields, including photovoltaics, biomedicine, and information technology. Developing these exciting applications is strongly dependent on understanding the fundamental properties of nanowires, such as their optical resonances and absorption spectra. In this thesis we explore optical absorption spectra of arrays of vertical III-V nanowires with a special emphasis on structures optimized to enhance absorption in the solar spectrum. First, we analyze experimentally determined absorption spectra of both indium phosphide (InP) and gallium phosphide (GaP) nanowire arrays. The study provides an intuitive understanding of how the observed absorption resonances in the nanowires may be tuned as a function of their geometrical parameters and crystal structure. As a consequence, the spectral position of absorption resonances can be precisely controlled through the nanowire diameter. However, the results highlight how the blue-shift in the optical absorption resonances as the diameter of the nanowires decreases comes to a halt at low diameters. The stop point is related to the behavior of the refractive indices of the nanowires. The wavelength of the stop is different for nanowire polytypes of similar dimensions due to differences in their refractive indices. We then present a theoretical argument that it is important to consider symmetry properties when tailoring the optical modes excited in the nanowires for enhanced absorption. We show that absorption spectra may be enhanced compared to vertical nanowires at normal incidence by tilting the nanowires with normal incidence light, or by using off-normal incidence with vertical nanowires. This is because additional optical modes inside the nanowires are excited when the symmetry is broken. Looking forward to omnidirectional applications, we consider branched nanowires as a way to enhance the absorption spectra at normal incidence by taking advantage of simultaneous excitation of the spectrally different optical modes in the branches and the stems. Third, we describe in theoretical terms how integrating distributed Bragg reflectors (DBRs) with the nanowires can improve absorption spectra compared to conventional nanowires. DBRs provide a way to employ light trapping mechanisms which increases the optical path length of the excited modes and thereby improves the absorption of the excited modes. At normal incidence, DBR-nanowires improve the absorption efficiency to 78%, compared to 72% for conventional nanowires. We show that the efficiency is increased to 85% for an off-normal incident angle of 50˚. Overall, our results show that studies of optical resonances in nanowires that take the light-matter interaction into account provide opportunities to develop novel optical and optoelectronic functionalities in nanoscience and nanotechnology.
39.	Agnarsson, Björn, 1977, et al. (författare) Low-temperature fabrication and characterization of a symmetric hybrid organic–inorganic slab waveguide for evanescent light microscopy 2018 Ingår i: Nano Futures. - : IOP Publishing. - 2399-1984. ; 2:2 Tidskriftsartikel (refereegranskat)abstract Organic and inorganic solid materials form the building blocks for most of today's high-technological instruments and devices. However, challenges related to dissimilar material properties have hampered the synthesis of thin-film devices comprised of both organic and inorganic films. We here give a detailed description of a carefully optimized processing protocol used for the construction of a three-layered hybrid organic–inorganic waveguide-chip intended for combined scattering and fluorescence evanescent-wave microscopy in aqueous environments using conventional upright microscopes. An inorganic core layer (SiO2 or Si3N4), embedded symmetrically in an organic cladding layer (CYTOP), aids simple, yet efficient in-coupling of light, and since the organic cladding layer is refractive index matched to water, low stray-light (background) scattering of the propagating light is ensured. Another major advantage is that the inorganic core layer makes the chip compatible with multiple well-established surface functionalization schemes that allows for a broad range of applications, including detection of single lipid vesicles, metallic nanoparticles or cells in complex environments, either label-free—by direct detection of scattered light—or by use of fluorescence excitation and emission. Herein, focus is put on a detailed description of the fabrication of the waveguide-chip, together with a fundamental characterization of its optical properties and performance, particularly in comparison with conventional epi illumination. Quantitative analysis of images obtained from both fluorescence and scattering intensities from surface-immobilized polystyrene nanoparticles in suspensions of different concentrations, revealed enhanced signal-to-noise and signal-to-background ratios for the waveguide illumination compared to the epi-illumination.
40.	Ahadi, Aylin, et al. (författare) Capturing nanoscale effects by peridynamics 2018 Ingår i: Mechanics of Advanced Materials and Structures. - : Informa UK Limited. - 1537-6494 .- 1537-6532. ; 25:13, s. 1115-1120 Tidskriftsartikel (refereegranskat)abstract Molecular dynamic simulations inevitably demand large computational resources for structures of liner measures even as small as a few tens or hundreds of nanometers. Thus, a computationally efficient method to simulate larger structures and, at the same time, retain the properties and the mechanical response at the atomic scale is in demand. One such approach is peridynamics, which is a nonlocal extension of continuum mechanics. In this study, we investigate the possibility to efficiently reproduce results from molecular dynamic (MD) simulations by calibration of two parameters inherent in peridynamics: the length scale parameter and the interparticle bond strength. The free-ware LAMMPS supports both numerical approaches, and thus LAMMPS has been used as the common framework. Beams of single-crystal fcc copper of various sizes and under tension along the crystallographic [100]- and [110]-directions act as the modeling example. The force–displacement curves and the elastic–plastic transitions have been compared between the approaches. The conclusion is that proper calibration of the peridynamic two parameters to MD simulations results in proper reproduction of the molecular dynamic results. This in turn allows for geometrical upscaling or simulation of geometrically more complicated structures, without loss of features derived from the atomic scale but to a much lower computational cost.
41.	Ahmadi Moghaddam, Elham (författare) Industrial nanoparticles health risks and advantages of a decent industrial ventilation system in reducing the related risks 2012 Konferensbidrag (övrigt vetenskapligt/konstnärligt)
42.	Aïssa, B., et al. (författare) Influence of single-walled carbon nanotubes induced exciton dissociation improvement on hybrid organic photovoltaic devices 2019 Ingår i: Journal of Applied Physics. - : AIP Publishing. - 0021-8979 .- 1089-7550. ; 126:11 Tidskriftsartikel (refereegranskat)abstract Torch-plasma-grown single-walled carbon nanotubes (SWCNTs) are integrated with regioregular poly(3-hexylthiophene) (P3HT) and a fullerene derivative 1-(3-methoxycarbonyl) propyl-1-phenyl[6,6]C61 (PCBM) as a hybrid photoactive layer for bulk heterojunction solar cell devices. We demonstrate that molecular information could be accurately obtained by time-of-flight secondary ion mass spectrometry throughout the hybrid organic photoactive solar cell layers when sputtering is performed using a Cs+ 2000 eV ion source. Furthermore, the photovoltaic (PV) performance of the fabricated devices show an increase in the short-circuit current density (Jsc) and the fill factor (FF) as compared to the pristine devices fabricated without SWCNTs. The best results are obtained with 0.5 wt. % SWCNT loads, where an open-circuit voltage (VOC) of 660 mV is achieved, with a Jsc of 9.95 mA cm-2 and a FF of 54%, leading to a power conversion efficiency of 3.54% (measured at standard test conditions, AM1.5 g). At this optimum SWCNT concentration of 0.5 wt. %, and to further understand the charge-transfer mechanisms taking place at the interfaces of P3HT:PCBM:SWCNT, Jsc is measured with respect to the light intensity and shows a linear dependency (in the double logarithmic scale), which implies that losses in the charge carrier are rather governed by monomolecular recombination. Finally, our results show that our hybrid devices benefit from the fullerene electron accepting nature and from the SWCNT fast electron transportation feature that improve substantially the exciton dissociation efficiency. The influence of the SWCNTs on the Fermi level and the work function of the photoactive composite and its impact on the PV performance is also investigated.
43.	Albinsson, Bo, 1963, et al. (författare) Electron Transfer Through Butadiyne-Linked Porphyrin-Based Molecular Wires 2012 Ingår i: Multiporphyrin Arrays: Fundamentals and Applications. - : Pan Stanford Publishing. - 9789814364287 ; , s. 55-90 Bokkapitel (övrigt vetenskapligt/konstnärligt)abstract Electron transfer is of fundamental importance in many areas of chemistry and biochemistry [1]. The ability to transfer charge eﬃciently over distances in the 10 nm range is crucial in various practical devices, such as organic transistors and solar cells both dye-sensitized metal oxide solar cells and bulk-heterojunction blend devices [2]. Furthermore, in the context of the ever-decreasing dimensions of integrated circuits, it is interesting to study charge transport through individual molecules [3]. Organic π -conjugated oligomers and polymers are attractive candidates as molecularwires, because modern synthetic chemistry can be used to create almost any type of π -conjugated backbone, while non-covalent interactions and supramolecular chemistry can be used to modify the backbone conformation. Interactions of conjugated oligomers, both with each other and with the external environment, can also be controlled by self-assembly and non-covalent encapsulation.
44.	Albinsson, David, 1990 (författare) Combining Nanoplasmonics and Nanofluidics for Single Particle Catalysis 2018 Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract Nanoparticles are, due to their large exposed surface area, widely used in the field of heterogeneous catalysis where they accelerate and steer chemical reactions. Although catalysis has been known about for centuries, the scrutiny of catalysts under realistic application conditions is still a major challenge. This difficulty originates from the fact that real catalyst materials are very complex, often consisting of large ensembles of nanoparticles that all are unique. Furthermore, the typically used macroscopic reactors in catalysis studies gives rise to locally, at the level of the active site, ill-defined reactant concentrations and diffusion limitations. To overcome these limitations, on one hand, techniques are being developed that are sensitive enough to probe individual catalytic particles and that at the same time can operate under realistic reaction conditions. On the other hand, strategies to more carefully control the amount and structure of catalyst material, as well as to precisely control mass transport to and from the active catalyst, are being investigated by scaling down the size of the used chemical reactor. To further push the limit of downsizing, in this thesis, I present a miniaturized reactor platform based on nanofluidic channels that have been carefully decorated with catalytic nanoparticles, and that is integrated with plasmonic nanospectroscopy readout. This optical technique relies on the nanoscale phenomenon known as the Localized Surface Plasmon Resonance (LSPR) and enables the study of individual metal nanoparticles in operando by means of dark-field scattering spectroscopy. As the first step in this development, we constructed a nanofluidic device with integrated plasmonic nanoparticles to detect minute changes in the liquid flowing through the channels, as well as molecules binding to the nanoparticles. As the second step, we developed the nanofluidic system with an integrated heater and to facilitate gas flow through the nanochannels with the possibility to connect to a mass spectrometer for on-line product analysis. This system was then successfully used to correlate activity with surface and bulk oxidation state changes taking place on individual catalytic Cu and Pt nanoparticles during CO oxidation, measured by means of plasmonic nanospectroscopy. To this end, in a separate study, I also employed the plasmonic approach to study the oxidation process of Cu nanoparticles both experimentally and by electrodynamics simulations.
45.	Albinsson, David, 1990, et al. (författare) Copper catalysis at operando conditions - bridging the gap between single nanoparticle probing and catalyst-bed-averaging 2020 Ingår i: Nature Communications. - : Springer Science and Business Media LLC. - 2041-1723 .- 2041-1723. ; 11:1 Tidskriftsartikel (refereegranskat)abstract In catalysis, nanoparticles enable chemical transformations and their structural and chemical fingerprints control activity. To develop understanding of such fingerprints, methods studying catalysts at realistic conditions have proven instrumental. Normally, these methods either probe the catalyst bed with low spatial resolution, thereby averaging out single particle characteristics, or probe an extremely small fraction only, thereby effectively ignoring most of the catalyst. Here, we bridge the gap between these two extremes by introducing highly multiplexed single particle plasmonic nanoimaging of model catalyst beds comprising 1000 nanoparticles, which are integrated in a nanoreactor platform that enables online mass spectroscopy activity measurements. Using the example of CO oxidation over Cu, we reveal how highly local spatial variations in catalyst state dynamics are responsible for contradicting information about catalyst active phase found in the literature, and identify that both surface and bulk oxidation state of a Cu nanoparticle catalyst dynamically mediate its activity.
46.	Alcer, David (författare) Single Junction and Tandem Junction Nanowire Solar Cells 2024 Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract Solar cells based on silicon are successfully harvesting solar energy in established and increasingly widespread solar panels. However, their efficiency is limited by the Shockley–Queisser limit. For certain applications where high efficiency is the key figure of merit, the use of multi-junction solar cells is desirable.III–V multi-junction solar cells exhibit the highest efficiencies achieved to date, but suffer from the high cost of the III–V materials.Arrays of III–V nanowires show strong light absorption while covering only a small fraction of the surface, minimizing materials consumption. Therefore, solar cells made from III–V nanowire arrays are a possible candidate to achieve high efficiencies at a fraction of the cost of traditional planar III–V solar cells. This thesis aims to contribute to the development of III–V nanowire solar cells by addressing some of the challenges the technology is facing.Concerning single junction nanowire solar cells, Paper I investigates the effects of the device size on the performance. In contrast to the commonly used devices in nanowire solar cell research with an area below 1×1mm2, significantly larger devices with an area of 10×10 mm² were processed, and the effects of device size on the external quantum efficiency (EQE) and J–V characteristics are investigated.A concept of optically transparent nanowire solar cells which can absorb near-infrared radiation is presented in Paper II.In the realm of nanowire synthesis, Paper III is a comparative study of two different Ga precursors to establish favorable conditions for the growth of GaInP nanowire segments. Paper IV reports on the successful processing of tandem junction nanowire solar cells based on a GaInP top junction and an InP bottom junction, connected by an Esaki tunnel diode.
47.	Andersen, Karsten Brandt, et al. (författare) Stability of diphenylalanine peptide nanotubes in solution 2011 Ingår i: Nanoscale. - : Royal Society of Chemistry (RSC). - 2040-3372 .- 2040-3364. ; 3:3, s. 994-998 Tidskriftsartikel (refereegranskat)abstract Over the last couple of years, self-organizing nanotubes based on the dipeptide diphenylalanine have received much attention, mainly as possible building blocks for the next generation of biosensors and as drug delivery systems. One of the main reasons for this large interest is that these peptide nanotubes are believed to be very stable both thermally and chemically. Previously, the chemical and thermal stability of self-organizing structures has been investigated after the evaporation of the solvent. However, it was recently discovered that the stability of the structures differed significantly when the tubes were in solution. It has been shown that, in solution, the peptide nanotubes can easily be dissolved in several solvents including water. It is therefore of critical importance that the stability of the nanotubes in solution and not after solvent evaporation be investigated prior to applications in which the nanotube will be submerged in liquid. The present article reports results demonstrating the instability and suggests a possible approach to a stabilization procedure, which drastically improves the stability of the formed structures. The results presented herein provide new information regarding the stability of self-organizing diphenylalanine nanotubes in solution.
48.	Andersson, Eric, 1992, et al. (författare) Fabrication and electrical transport characterization of high quality underdoped YBa2Cu3O7-δ nanowires 2020 Ingår i: Superconductor Science and Technology. - : IOP Publishing. - 0953-2048 .- 1361-6668. ; 33:6 Tidskriftsartikel (refereegranskat)abstract We present the fabrication and electrical transport characterization of underdoped YBa2Cu3O7-δnanowires. The nanowires have been realized without any protective capping layer and theyshow transport properties similar to those of the parent thin film, demonstrating that they havenot been damaged by the nanopatterning. The current-voltage characteristics of the underdopednanowires show large hysteretic voltage switching at the critical current, in contrast to theflux-flow like characteristics of optimally doped nanostructures, indicating the formation of aself-stabilizing hot spot. These results open up new possibilities for using the underdopednanowires as single photon detectors and for exploring the underdoped side of the YBa2Cu3O7-δphase diagram at the nanoscale.
49.	Andersson, M, et al. (författare) Macroscopic alignment of silver nanoparticles in reverse hexagonal liquid crystalline templates 2002 Ingår i: Nano Letters. - : American Chemical Society (ACS). - 1530-6992 .- 1530-6984. ; 2:12, s. 1403-1407 Tidskriftsartikel (refereegranskat)abstract A flexible method of preparing and macroscopically aligning nanoparticles of crystalline silver into millimeter long fibers is presented. The approach utilizes the dual functionality of a reverse hexagonal liquid crystalline template containing a built-in reducing agent facing the aqueous domain. The method is advantageous in that its slow kinetics allows for a thorough introduction of a silver salt into the liquid crystal before the reduction takes place, allowing for an efficient loading of he template and a retained mesoscopic ordering as evidenced by SAXS. It was confirmed by H-1 NMR that the oxyethylene groups of the amphiphilic polymer reduce the silver ions while being oxidized to aldehydes. The silver nanoparticles are uniform in size and in the same size range as the diameter of the aqueous domain of the liquid crystal (3 nm), further supporting that the silver particles form inside the liquid crystal. TEM images confirm the macroscopic alignment of silver nanoparticles into fibrils and the packing of fibrils into millimeter long fibers. The diameter of the fibrils and fibers ranges from 30 nm to several hundreds of micrometers. Electron diffraction analysis of a collection of silver nanoparticles confirms their crystallinity as three diffraction rings could be indexed to the face centered cubic structure of silver. A key to the successful macroscopic alignment of the nanoparticles is that the particles are formed inside the liquid crystal, thus minimizing the need for their diffusion i to and inside the liquid crystal.
50.	Andrén, Daniel, 1991 (författare) Optical manipulation and heating of gold nanoparticles near interfaces 2018 Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract By focusing laser light to small volumes, its momentum can be used to trap and manipulate objects in the size range from cells down to single atoms. Devices using this effect are called optical tweezers, and have found use in measuring and applying minuscule forces and torques, contributed to deepening our knowledge of molecular motors, unraveling the mechanics of cells and DNA, and better understand statistical mechanics and hydrodynamic interactions at the nanoscale. In short, the optical tweezer is a crucial component in our aspiration to understand and unlock the potential of nano-scaled objects. One class of nano-elements worth devoting special attention to are nanoparticles supporting plasmonic resonances. These present strongly enhanced light-matter interactions and may find use in as diverse fields as high-density data storage, single molecule detection, and personalized medicine. One potential use of plasmonic nanorods is as rotary nanomotors. These are capable of reaching record rotation frequencies of several tens of kilohertz when optically trapped in water against a glass surface. This thesis focuses on studying vital questions related to such rotary nanomotors, which are interesting to resolve from both a fundamental and from an applied point of view. It is well-known that metallic nanoparticles are efficiently heated by light. This will give rise to several photothermal effects affecting the nanoparticle and its surrounding. How these influence the performance of the nanomotor is evaluated. Through spectroscopic measurements, morphological changes induced by atomic migration is observed. Moreover, the elevated thermal environment around the nanoparticle is probed using two separate techniques, and temperatures above $200^\circ$C are routinely reached, but could be kept as low as a few degrees above ambient under the right circumstances. The gold nanoparticle is trapped at a small, but hitherto unknown, distance from a glass interface. The vicinity to a surface can affect several of a nanoparticles properties, including its diffusion and thermal environment, and knowing this distance is hence critical for any claims about the nanomotors' performance. Therefore, total internal reflection microscopy is performed on the trapped nanoparticles and it is found that they are confined less than 100 nm from the surface. The distance can be controlled by altering the radiation pressure, or Coulomb repulsion. In summary, the work performed in this thesis present important building blocks towards a complete understanding of this highly promising rotary motor system.

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