| 1. |
- Sheng, Renwang, et al.
(författare)
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Material stiffness in cooperation with macrophage paracrine signals determines the tenogenic differentiation of mesenchymal stem cells
- 2023
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Ingår i: Advanced Science. - : John Wiley & Sons. - 2198-3844. ; 10:17
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Tidskriftsartikel (refereegranskat)abstract
- Stiffness is an important physical property of biomaterials that determines stem cell fate. Guiding stem cell differentiation via stiffness modulation has been considered in tissue engineering. However, the mechanism by which material stiffness regulates stem cell differentiation into the tendon lineage remains controversial. Increasing evidence demonstrates that immune cells interact with implanted biomaterials and regulate stem cell behaviors via paracrine signaling; however, the role of this mechanism in tendon differentiation is not clear. In this study, polydimethylsiloxane (PDMS) substrates with different stiffnesses are developed, and the tenogenic differentiation of mesenchymal stem cells (MSCs) exposed to different stiffnesses and macrophage paracrine signals is investigated. The results reveal that lower stiffnesses facilitates tenogenic differentiation of MSCs, while macrophage paracrine signals at these stiffnesses suppress the differentiation. When exposed to these two stimuli, MSCs still exhibit enhanced tendon differentiation, which is further elucidated by global proteomic analysis. Following subcutaneous implantation in rats for 2 weeks, soft biomaterial induces only low inflammation and promotes tendon-like tissue formation. In conclusion, the study demonstrates that soft, rather than stiff, material has a greater potential to guide tenogenic differentiation of stem cells, which provides comprehensive evidence for optimized bioactive scaffold design in tendon tissue engineering.
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| 2. |
- Bagheri, Niusha, et al.
(författare)
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Change in the emission saturation and kinetics of upconversion nanoparticles under different light irradiations
- 2019
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Ingår i: Optical materials (Amsterdam). - : Elsevier. - 0925-3467 .- 1873-1252. ; 97
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Tidskriftsartikel (refereegranskat)abstract
- Nd3+-sensitized upconversion nanoparticles (UCNPs) can be excited by both 980 and 808 nm light, which is regarded as a particularly advantageous property of these particles. In this work, we demonstrate that the nanoparticles can exhibit significantly different response when excited at these two excitation wavelengths, showing dependence on the intensity of the excitation light and the way it is distributed in time. Specifically, with 808 nm excitation saturation in the emitted luminescence is more readily reached with increasing excitation intensities than upon 980 nm excitation. This is accompanied by delayed upconversion luminescence (UCL) kinetics and weaker UCL intensities. The different luminescence response at 808 and 980 nm excitation reported in this work is relevant in a manifold of applications using UCNPs as labels and sensors. This could also open new possibilities for multi-wavelength excitable UCNPs for upconversion color display and in laser-scanning microscopy providing selective readouts and sub-sectioning of samples.
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| 3. |
- Bergstrand, Jan, et al.
(författare)
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On the decay time of upconversion luminescence
- 2019
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Ingår i: Nanoscale. - : Royal Society of Chemistry. - 2040-3364 .- 2040-3372. ; 11:11, s. 4959-4969
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Tidskriftsartikel (refereegranskat)abstract
- In this study, we systematically investigate the decay characteristics of upconversion luminescence (UCL) under anti-Stokes excitation through numerical simulations based on rate-equation models. We find that a UCL decay profile generally involves contributions from the sensitizer's excited-state lifetime, energy transfer and cross-relaxation processes. It should thus be regarded as the overall temporal response of the whole upconversion system to the excitation function rather than the intrinsic lifetime of the luminescence emitting state. Only under certain conditions, such as when the effective lifetime of the sensitizer's excited state is significantly shorter than that of the UCL emitting state and of the absence of cross-relaxation processes involving the emitting energy level, the UCL decay time approaches the intrinsic lifetime of the emitting state. Subsequently, Stokes excitation is generally preferred in order to accurately quantify the intrinsic lifetime of the emitting state. However, possible cross-relaxation between doped ions at high doping levels can complicate the decay characteristics of the luminescence and even make the Stokes-excitation approach fail. A strong cross-relaxation process can also account for the power dependence of the decay characteristics of UCL.
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| 4. |
- Du, Yaoyao, et al.
(författare)
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Cartilage Oligomeric Matrix Protein Inhibits Vascular Smooth Muscle Calcification by Interacting With Bone Morphogenetic Protein-2.
- 2011
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Ingår i: Circulation Research. - 1524-4571. ; 108, s. 79-917
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Tidskriftsartikel (refereegranskat)abstract
- Rationale: Vascular calcification is a significant contributor to cardiovascular morbidity and mortality. We recently reported that cartilage oligomeric matrix protein (COMP) is pivotal for maintaining the homeostasis of vascular smooth muscle cells (VSMCs). Whether COMP affects the process of vascular calcification is unknown. Objective: We aimed to test whether COMP modulates vascular calcification. Methods and Results: VSMC calcification in vitro was induced by calcifying media containing high inorganic phosphate or calcium. In vivo medial vessel calcification was induced in rats by 5/6 nephrectomy with a high-phosphate diet or by periadventitial application of CaCl(2) to the abdominal aorta. COMP protein level was markedly reduced in both calcified VSMCs and arteries. COMP deficiency remarkably exacerbated VSMC calcification, whereas ectopic expression of COMP greatly reduced calcification. Furthermore, COMP knockdown facilitated osteogenic markers expression by VSMCs even in the absence of calcifying media. By contrast, COMP overexpression significantly inhibited high phosphate- or high calcium-induced VSMC osteochondrogenic transition. Induction of osteogenic marker expression by COMP silencing was reversed by a soluble form of bone morphogenetic protein (BMP)-2 receptor IA, which suggests a BMP-2-dependent mechanism. Our data revealed that COMP bound directly to BMP-2 through the C terminus, inhibited BMP-2 receptor binding, and blocked BMP-2 osteogenic signaling, indicating COMP inhibits osteochondrogenic transition of VSMCs at least partially through inhibiting BMP-2. Conclusions: Our data strongly suggest that COMP is a novel inhibitor of vascular calcification. The imbalance between the effects of COMP and BMP-2 may provide new insights into the pathophysiology of vascular calcification.
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| 5. |
- Ji, Yanan, et al.
(författare)
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Cascade photon upconversion amplification for selective multispectral narrow-band near-infrared photodetection
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Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- Facing the fact that selective detection of multiple narrow spectral bands in the near-infrared (NIR) region still poses a fundamental challenge, we have, in this work, developed NIR photodetectors (PDs) using photon upconversion nanocrystals (UCNCs) combined with perovskite films. In order to conquer the relatively high pumping threshold of UCNCs, we designed a novel cascade amplification strategy for upconversion luminescence (UCL) through cascading the superlensing effect of dielectric microlens arrays and the plasmonic effect of gold nanorods, which readily leads to a UCL enhancement by more than four orders of magnitude under weak light irradiation. By accommodating multiple optical active lanthanide ions in a core-shell-shell hierarchical architecture, the developed PDs on top can detect three well-separated narrow bands in the NIR region, i.e., 808, 980, and 1540 nm, respectively. Due to the large UCL enhancement, the obtained PDs demonstrate extremely high responsivity of 30.73, 23.15, 12.20 A/W and detectivity of 5.36, 3.45, 1.91x10^11 Jones for the 808, 980, and 1540 nm light detection, respectively, together with short response times in the range of 80-120 ms. Moreover, we demonstrate for the first time that the response to the excitation modulation frequency of a PD can be employed to discriminate the incident light wavelength. We believe that our work provides a novel insight for developing NIR PDs, and that it can spur the development of other applications using upconversion nanotechnology.
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| 6. |
- Labrador-Páez, Lucia, et al.
(författare)
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Excitation Pulse Duration Response of Upconversion Nanoparticles and Its Applications
- 2022
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Ingår i: The Journal of Physical Chemistry Letters. - : American Chemical Society (ACS). - 1948-7185. ; 13:48, s. 11208-11215
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Tidskriftsartikel (refereegranskat)abstract
- Lanthanide-doped upconversion nanoparticles (UCNPs) have rich photophysics exhibiting complex luminescence kinetics. In this work, we thoroughly investigated the luminescence response of UCNPs to excitation pulse durations. Analyzing this response opens new opportunities in optical encoding/decoding and the assignment of transitions to emission peaks and provides advantages in applications of UCNPs, e.g., for better optical sectioning and improved luminescence nanothermometry. Our work shows that monitoring the UCNP luminescence response to excitation pulse durations (while keeping the duty cycle constant) by recording the average luminescence intensity using a low-time resolution detector such as a spectrometer offers a powerful approach for significantly extending the utility of UCNPs.
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| 7. |
- Li, Wei, et al.
(författare)
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Non-lab and semi-lab algorithms for screening undiagnosed diabetes : A cross-sectional study
- 2018
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Ingår i: EBioMedicine. - : ELSEVIER SCIENCE BV. - 2352-3964. ; 35, s. 307-316
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Tidskriftsartikel (refereegranskat)abstract
- Background: The terrifying undiagnosed rate and high prevalence of diabetes have become a public emergency. A high efficiency and cost-effective early recognition method is urgently needed. We aimed to generate innovative, user-friendly nomograms that can be applied for diabetes screening in different ethnic groups in China using the non-lab or noninvasive semi-lab data. Methods: This multicenter, multi-ethnic, population-based, cross-sectional study was conducted in eight sites in China by enrolling subjects aged 20-70. Sociodemographic and anthropometric characteristics were collected. Blood and urine samples were obtained 2 h following a standard 75 g glucose solution. In the final analysis, 10,794 participants were included and randomized into model development (n - 8096) and model validation (n = 2698) group with a ratio of 3:1. Nomograms were developed by the stepwise binary logistic regression. The nomograms were validated internally by a bootstrap sampling method in the model development set and externally in the model validation set. The area under the receiver operating characteristic curve (AUC) was used to assess the screening performance of the nomograms. Decision curve analysis was applied to calculate the net benefit of the screening model. Results: The overall prevalence of undiagnosed diabetes was 9.8% (1059/10794) according to ADA criteria. The non-lab model revealed that gender, age, body mass index, waist circumference, hypertension, ethnicities, vegetable daily consumption and family history of diabetes were independent risk factors for diabetes. By adding 2 h post meal glycosuria qualitative to the non-lab model, the semi-lab model showed an improved Akaike information criterion (AIC: 4506 to 3580). The AUC of the semi-lab model was statistically larger than the non-lab model (0.868 vs 0.763, P < 0.001). The optimal cutoff probability in semi-lab and non-lab nomograms were 0.088 and 0.098, respectively. The sensitivity and specificity were 76.3% and 81.6%, respectively in semi-lab nomogram, and 72.1% and 673% in non-lab nomogram at the optimal cut off point. The decision curve analysis also revealed a bigger decrease of avoidable OGTT test (52 per 100 subjects) in the semi-lab model compared to the non-lab model (36 per 100 subjects) and the existed New Chinese Diabetes Risk Score (NCDRS, 35 per 100 subjects). Conclusion: The non-lab and semi-lab nomograms appear to be reliable tools for diabetes screening, especially in developing countries. However, the semi-lab model outperformed the non-lab model and NCDRS prediction systems and might be worth being adopted as decision support in diabetes screening in China.
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| 8. |
- Liu, Qingyun, 1993-, et al.
(författare)
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High throughput decoding approach for luminescencekinetics-based optical encoding of lanthanide upconversion nanoparticles
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Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- Lanthanide upconversion nanoparticles (UCNPs) are increasingly explored to develop high-security-level anti-counterfeiting and multiplexing applications, due to the availability of ample encoding dimensions. Among other applications, upconversion luminescence(UCL) kinetics-based optical encoding is particularly attractive as it provides an almost unlimited encoding capacity due to the ease of manipulating the UCL kinetics by chemical engineering. However, current decoding methods limit its applications because of a typically low throughput and high cost of the system. In this Letter, we propose a novel decoding approach for UCL kinetics-based optical encoding, which utilizes a pulsed excitation source with adjustable pulse duration and a low time-resolution and large-area detector. We develop a theoretical fitting model and show how fingerprint time constants of the UCNPs (the encoding identities) can be extracted from the correlation between the averaged UCL intensity and the pulse duration. Our new approach provides a high-throughput and cost-effective solution to decode UCL kinetics.
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| 9. |
- Liu, Qingyun, et al.
(författare)
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Microlens array enhanced upconversion luminescence at low excitation irradiance
- 2019
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Ingår i: Nanoscale. - : ROYAL SOC CHEMISTRY. - 2040-3364 .- 2040-3372. ; 11:29, s. 14070-14078
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Tidskriftsartikel (refereegranskat)abstract
- The dearth of high upconversion luminescence (UCL) intensity at low excitation irradiance hinders the prevalent application of lanthanide-doped upconversion nanoparticles (UCNPs) in many fields ranging from optical bioimaging to photovoltaics. In this work, we propose to use microlens arrays (MLAs) as spatial light modulators to manipulate the distribution of excitation light fields in order to increase UCL, taking advantage of its nonlinear response to the excitation irradiance. We show that multicolored UCL from NaYF4:Yb3+,Er3+@NaYF4:Yb3+,Nd3+ and NaYF4:Yb3+,Tm3+@NaYF4:Yb3+,Nd3+ core/shell UCNPs can be increased by more than one order of magnitude under either 980 or 808 nm excitation, by simply placing a polymeric MLA onto the top of these samples. The observed typical green (525/540 nm) and red (654 nm) UCL bands from Er3+ and a blue (450/475 nm) UCL band from Tm3+ exhibit distinct enhancement factors due to their different multi-photon processes. Importantly, our ray tracing simulation reveals that the MLA is able to spatially confine the excitation light (980 and 808 nm) by orders of magnitude, thus amplifying UCL by more than 225-fold (the 450 nm UCL band of Tm3+) at low excitation irradiance. The proposed MLA method has immediate ramifications for the improved performance of all types of UCNP-based devices, such as UCNP-enhanced dye sensitized solar cells demonstrated here.
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| 10. |
- Liu, Qingyun
(författare)
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Studies of optical properties of lanthanide upconversion nanoparticles for emerging applications.
- 2020
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- YTTERBY, a small village very close to Stockholm where I live, is the place in the world which has lent its name to the largest number of elements in the periodic table, namely four - YTTRIUM, YTTERBIUM, ERBIUM and TERBIUM. Three more lanthanide elements were discovered from the now empty quarry located in this village. By the time of their discoveries in the 19th century little could be known about their fantastic properties, the versatility of their use and functionality in what we now call nanotechnology. This is a circumstance that motivated me to rather recently enter lanthanide research, in particular studies of their outstanding optical properties for the purpose of information technology and energy harvesting.So far, upconversion nanoparticles (UCNPs) have been much explored as unique spectral converters for various applications, like biotechnology, information technology and photovoltaic devices due to properties like sharp emission profiles, low autofluorescence and large anti-Stoke shifts. Still, there is much to explore and to understand in order to fully utilize the very unique properties of UCNPs. The kinetic dynamics of the upconversion process is one such aspect that is not well understood, and a deeper understanding of the kinetic dynamics of lanthanide upconversion systems could thus broaden their applications. Therefore, the work of this thesis is focused on investigating the kinetic dynamics of upconversion processes mainly based on systems with NaYF4 as host material, and Yb3+/Er3+ or Yb3+/Tm3+ embedded as sensitizer/activator. Through rate equation models, the kinetic dynamics of upconversion are comparatively investigated with numerical simulations and analytical derivation. The temporal response regarding upconverted luminescence and quantum yield power density dependence, excitation duration response and excitation frequency response of the upconversion systems are investigated and the corresponding applications for multicolor imaging, optical encoding, photovoltaics, IR photodetectors are explored and analyzed in the thesis, taking advantage of the kinetic properties.
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| 11. |
- Tang, Yunyu, et al.
(författare)
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Solar cells sensitized by porphyrin dyes containing a substituted carbazole donor with synergistically extended absorption and suppressed the dye aggregation
- 2020
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Ingår i: Chinese Chemical Letters. - : Elsevier BV. - 1001-8417 .- 1878-5964. ; 31:7, s. 1927-1930
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Tidskriftsartikel (refereegranskat)abstract
- To achieve high power conversion efficiencies (PCEs), three porphyrin sensitizers have been synthesized and explored to simultaneously enhance the photocurrent (Jsc) and photovoltage (Voc). On basis of the XW4, a benzothiadiazole (BTD) unit has been introduced to afford XW57 with the aim to extend the absorption wavelength and enhance the light harvesting ability. As a result, a Jsc of 13.72 mA/cm2 has been obtained for XW57, higher than that of XW4. On this basis, XW58 has been prepared by modifying the carbazole-based donor with two bulky dihexyloxyphenyl groups, and the superior anti-aggregation character raises the Voc from 781 mV (XW4) to 844 mV. When both the BTD unit and the bulky groups are introduced to the acceptor and donor units, respectively, the resulting sensitizer XW59 exhibits a highest PCE value of 7.34% with synergistically enhanced Jsc of 13.19 mA/cm2 and Voc of 793 mV. These results provide further insight into developing high performance dye-sensitized solar cells
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| 12. |
- Chen, Jialin, et al.
(författare)
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Hydroxycamptothecin and substratum stiffness synergistically regulate fibrosis of human corneal fibroblasts
- 2023
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Ingår i: ACS Biomaterials Science & Engineering. - : American Chemical Society (ACS). - 2373-9878. ; 9:2, s. 959-967
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Tidskriftsartikel (refereegranskat)abstract
- Corneal fibrosis is a common outcome of inappropriate repair associated with trauma or ocular infection. Altered biomechanical properties with increased corneal stiffness is a feature of fibrosis that cause corneal opacities, resulting in severe visual impairment and even blindness. The present study aims to determine the effect of hydroxycamptothecin (HCPT) and matrix stiffness on transforming growth factor-β1 (TGF-β1)-induced fibrotic processes in human corneal fibroblasts (HTK cells). HTK cells were cultured on substrates with different stiffnesses ("soft", ∼261 kPa; "stiff", ∼2.5 × 103 kPa) and on tissue culture plastic (TCP, ∼106 kPa) and simultaneously treated with or without 1 μg/mL HCPT and 10 ng/mL TGF-β1. We found that HCPT induced decreased cell viability and antiproliferative effects on HTK cells. TGF-β1-induced expression of fibrosis-related genes (FN1, ACTA2) was reduced if the cells were simultaneously treated with HCPT. Substrate stiffness did not affect the expression of fibrosis-related genes. The TGF-β1 induced expression of FN1 on both soft and stiff substrates was reduced if cells were simultaneously treated with HCPT. However, this trend was not seen for ACTA2, i.e., the TGF-β1 induced expression of ACTA2 was not reduced by simultaneous treatment of HCPT in either soft or stiff substrate. Instead, HCPT treatment in the presence of TGF-β1 resulted in increased gene expression of keratocyte phenotype makers (LUM, KERA, AQP1, CHTS6) on both substrate stiffnesses. In addition, the protein expression of keratocyte phenotype makers LUM and ALDH3 was increased in HTK cells simultaneously treated with TGF-β1 and HCPT on stiff substrate as compared to control, i.e., without HCPT. In conclusion, we found that HCPT can reduce TGF-β1-induced fibrosis and promote the keratocyte phenotype in a substrate stiffness dependent manner. Thus, HCPT stimulation might be an approach to stimulate keratocytes in the appropriate healing stage to avoid or reverse fibrosis and achieve more optimal corneal wound healing.
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| 13. |
- Jamshidi Zavaraki, Asghar, et al.
(författare)
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Solar cell sensitized with “green” InP-ZnS quantum dots : Effect of ZnS shell deposition
- 2020
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Ingår i: Nano-Structures and Nano-Objects. - : Elsevier BV. - 2352-507X. ; 22
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Tidskriftsartikel (refereegranskat)abstract
- Colloidal InP and ZnS-coated InP quantum dots (QDs) were synthesized by hot injection method and successfully employed as sensitizer for the first time in quantum dot sensitized solar cells (QDSSCs). Colloidal InP QDs has not been used in QDSSCs due to low stability and high sensitivity to the moisture. In this work ZnS-coating were applied as a strategy to increase the stability and protect InP against moisture and interaction with electrolyte. The nature of low toxicity of such QDs compared to high toxic Cd-based QDs was the main idea to employ “green” and heavy metal-free InP-ZnS QDs for future solar cell application. It is found that ZnS shell-coating caused the absorption onset to shift toward longer wavelength and broader absorption. In the solar cell device, ZnS shell not only acts as protection agent and increases the life time for InP QDs but also enhances the power conversion efficiency by more than 2 times.
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| 14. |
- Lu, Yunyue, et al.
(författare)
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Multiply Wrapped Porphyrin Dyes with a Phenothiazine Donor : A High Efficiency of 11.7% Achieved through a Synergetic Coadsorption and Cosensitization Approach
- 2019
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Ingår i: ACS Applied Materials and Interfaces. - : AMER CHEMICAL SOC. - 1944-8244 .- 1944-8252. ; 11:5, s. 5046-5054
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Tidskriftsartikel (refereegranskat)abstract
- Photocurrent (J) and photovoltage (Vac) are two important parameters for dye-sensitized solar cells (DSSCs) to achieve high power conversion efficiencies (PCEs). Herein, we synthesize four novel porphyrin dyes, XW36 XW39, using an N-phenyl-substituted phenothiazine donor to pursue higher PCE. For XW36 and XW37, the N-phenyl group is wrapped with two ortho-alkoxy chains. In contrast, it is substituted with a para-alkoxy group in XW38 and XW39. The phenothiazine wrapping in XW36 and XW37 induces more serious distortion, which is beneficial for anti-aggregation but unfavorable for the electron transfer from donor to a porphyrin framework. Thus, individual porphyrin dyes XW36 and XW37 exhibit efficiencies of 9.05 and 9.58%, respectively, lower than those of 9.51 and 10.0% achieved for XW38 and XW39, respectively. Besides, the introduction of a methyl group into a benzoic acid acceptor unit is conducive to anti-aggregation and thus improves the V-oc and efficiencies. Therefore, higher efficiencies were achieved for XW37 and XW39, compared with XW36 and XW38, respectively. Interestingly, although the individual XW36 dye shows a lowest efficiency among the four dyes, a highest efficiency of 11.7% was obtained for XW36 on the basis of synergetic adsorption with chenodeoxycholic acid and PT-C6 because of simultaneously improved J and Voc, which may be ascribed to the lowest dye-loading amount of XW36 among all of these porphyrin dyes, with the largest vacancy area left on the TiO2 surface available for cosensitizer PT-C6, resulting in a highest J. The high efficiency of 11.7% is one of the highest efficiencies using I-/I-3(-) electrolytes in DSSCs. These results provide an effective strategy for developing efficient DSSCs by the targeted coadsorption and cosensitization of porphyrin sensitizers optimized through introducing a bis(ortho-alkoxy)-wrapped phenyl group into the phenothiazine donor and/or methyl groups into the benzoic acid acceptor unit.
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| 15. |
- Shattuck Eidens, Donna, et al.
(författare)
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A Collaborative Survey of 80 Mutations in the BRCA1 Breast and Ovarian Cancer Susceptibility Gene : Implications for Presymptomatic Testing and Screening
- 1995
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Ingår i: JAMA: The Journal of the American Medical Association. - : American Medical Association (AMA). - 0098-7484. ; 273:7, s. 535-541
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Tidskriftsartikel (refereegranskat)abstract
- OBJECTIVES:To report the initial experience of an international group of investigators in identifying mutations in the BRCA1 breast and ovarian cancer susceptibility gene, to assess the spectrum of such mutations in samples from patients with different family histories of cancer, and to determine the frequency of recurrent mutations.DESIGN:Nine laboratories in North America and the United Kingdom tested for BRCA1 mutations in DNA samples obtained from a total of 372 unrelated patients with breast or ovarian cancer largely chosen from high-risk families. Three of these laboratories also analyzed a total of 714 additional samples from breast or ovarian cancer cases, including 557 unselected for family history, for two specific mutations that had been found to recur in familial samples.PARTICIPANTS:A total of 1086 women with either breast or ovarian cancer.MAIN OUTCOME MEASURE:The detection of sequence variation in patients' DNA samples that is not found in sets of control samples.RESULTS:BRCA1 mutations have now been identified in a total of 80 patient samples. Thirty-eight distinct mutations were found among 63 mutations identified through a complete screen of the BRCA1 gene. Three specific mutations appeared relatively common, occurring eight, seven, and five times, respectively. When specific tests for the two most common mutations were performed in larger sets of samples, they were found in 17 additional patients. Mutations predicted to result in a truncated protein accounted for 86% of the mutations detected by complete screening.CONCLUSIONS:The high frequency of protein-terminating mutations and the observation of many recurrent mutations found in a diverse set of samples could lead to a relatively simple diagnostic test for BRCA1 mutations. More data must be accumulated to address specifically the sensitivity and specificity of such a diagnostic testing procedure and to better estimate the age-specific risk for breast and ovarian cancer associated with such mutations.
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| 16. |
- Tang, Yunyu, et al.
(författare)
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Solar cells sensitized with porphyrin dyes with a carbazole donor : The effects of an auxiliary benzothiadiazole acceptor and bulky substituents on the donor
- 2019
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Ingår i: Dyes and pigments. - : ELSEVIER SCI LTD. - 0143-7208 .- 1873-3743. ; 171
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Tidskriftsartikel (refereegranskat)abstract
- Three porphyrin sensitizers XW54-XW56 containing a carbazole donor have been designed and synthesized by introducing a benzothiadiazole (BTD) unit as the auxiliary electron acceptor to extend the absorption spectra and/or bulky dihexyloxyphenyl groups into the carbazole unit to suppress dye aggregation and improve the photovoltage (V-OC). The BTD unit incorporated in XW54 obviously broadens and red-shifts the absorption threshold to ca. 700 nm, as compared with that of 650 nm observed for XW1. Thus, XW54 exhibits a much broader monochromatic photon-to-electron conversion efficiency (IPCE) spectrum with an extremely red-shifted onset wavelength of 780 nm, resulting in a photocurrent density (J(SC)) of 11.60 mA cm(-2), higher than that of XW1. Unfortunately, the V-OC value was decreased owing to the more severe dye aggregation caused by the large conjugation framework induced by the presence of the BTD unit. As a result, XW54 shows an efficiency of 6.26%, slightly higher than that of 6.11% obtained for XW1. On the other hand, with the bulky dihexyloxyphenyl donor groups introduced to XW55, a highest V-OC, of 860 mV was achieved, which can be ascribed to the efficient prevention of charge recombination and suppression of dye aggregation. Thus, XW55-based cells exhibit an improved efficiency of 6.60%. On the basis of XW54 and XW55, two bulky dihexyloxyphenyl groups and a BTD unit were simultaneously introduced to XW56, affording a highest efficiency of 7.03%, with the J(SC )and V-OC, values of 12.5 mA cm(-2) and 785 mV, respectively. These results compose a novel approach for developing efficient dye-sensitized solar cells (DSSCs) by simultaneously introducing bulky dihexyloxyphenyl groups and a benzothiadiazole unit, which may synergistically broaden the absorption spectra and suppress the dye aggregation, resulting in improved photocurrent and photovoltage.
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| 17. |
- Wei, Ting, et al.
(författare)
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Developed and developing world responsibilities for historical climate change and CO2 mitigation
- 2012
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Ingår i: Proceedings of the National Academy of Sciences of the United States of America. - : Proceedings of the National Academy of Sciences. - 0027-8424 .- 1091-6490. ; 109:32, s. 12911-12915
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Tidskriftsartikel (refereegranskat)abstract
- At the United Nations Framework Convention on Climate Change Conference in Cancun, in November 2010, the Heads of State reached an agreement on the aim of limiting the global temperature rise to 2 degrees C relative to preindustrial levels. They recognized that long-term future warming is primarily constrained by cumulative anthropogenic greenhouse gas emissions, that deep cuts in global emissions are required, and that action based on equity must be taken to meet this objective. However, negotiations on emission reduction among countries are increasingly fraught with difficulty, partly because of arguments about the responsibility for the ongoing temperature rise. Simulations with two earth-system models (NCAR/CESM and BNU-ESM) demonstrate that developed countries had contributed about 60-80%, developing countries about 20-40%, to the global temperature rise, upper ocean warming, and sea-ice reduction by 2005. Enacting pledges made at Cancun with continuation to 2100 leads to a reduction in global temperature rise relative to business as usual with a 1/3-2/3 (CESM 33-67%, BNU-ESM 35-65%) contribution from developed and developing countries, respectively. To prevent a temperature rise by 2 degrees C or more in 2100, it is necessary to fill the gap with more ambitious mitigation efforts.
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