| 1. |
- Backes, Claudia, et al.
(författare)
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Production and processing of graphene and related materials
- 2020
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Ingår i: 2D Materials. - : IOP Publishing. - 2053-1583. ; 7:2
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Tidskriftsartikel (refereegranskat)abstract
- We present an overview of the main techniques for production and processing of graphene and related materials (GRMs), as well as the key characterization procedures. We adopt a 'hands-on' approach, providing practical details and procedures as derived from literature as well as from the authors' experience, in order to enable the reader to reproduce the results. Section I is devoted to 'bottom up' approaches, whereby individual constituents are pieced together into more complex structures. We consider graphene nanoribbons (GNRs) produced either by solution processing or by on-surface synthesis in ultra high vacuum (UHV), as well carbon nanomembranes (CNM). Production of a variety of GNRs with tailored band gaps and edge shapes is now possible. CNMs can be tuned in terms of porosity, crystallinity and electronic behaviour. Section II covers 'top down' techniques. These rely on breaking down of a layered precursor, in the graphene case usually natural crystals like graphite or artificially synthesized materials, such as highly oriented pyrolythic graphite, monolayers or few layers (FL) flakes. The main focus of this section is on various exfoliation techniques in a liquid media, either intercalation or liquid phase exfoliation (LPE). The choice of precursor, exfoliation method, medium as well as the control of parameters such as time or temperature are crucial. A definite choice of parameters and conditions yields a particular material with specific properties that makes it more suitable for a targeted application. We cover protocols for the graphitic precursors to graphene oxide (GO). This is an important material for a range of applications in biomedicine, energy storage, nanocomposites, etc. Hummers' and modified Hummers' methods are used to make GO that subsequently can be reduced to obtain reduced graphene oxide (RGO) with a variety of strategies. GO flakes are also employed to prepare three-dimensional (3d) low density structures, such as sponges, foams, hydro- or aerogels. The assembly of flakes into 3d structures can provide improved mechanical properties. Aerogels with a highly open structure, with interconnected hierarchical pores, can enhance the accessibility to the whole surface area, as relevant for a number of applications, such as energy storage. The main recipes to yield graphite intercalation compounds (GICs) are also discussed. GICs are suitable precursors for covalent functionalization of graphene, but can also be used for the synthesis of uncharged graphene in solution. Degradation of the molecules intercalated in GICs can be triggered by high temperature treatment or microwave irradiation, creating a gas pressure surge in graphite and exfoliation. Electrochemical exfoliation by applying a voltage in an electrolyte to a graphite electrode can be tuned by varying precursors, electrolytes and potential. Graphite electrodes can be either negatively or positively intercalated to obtain GICs that are subsequently exfoliated. We also discuss the materials that can be amenable to exfoliation, by employing a theoretical data-mining approach. The exfoliation of LMs usually results in a heterogeneous dispersion of flakes with different lateral size and thickness. This is a critical bottleneck for applications, and hinders the full exploitation of GRMs produced by solution processing. The establishment of procedures to control the morphological properties of exfoliated GRMs, which also need to be industrially scalable, is one of the key needs. Section III deals with the processing of flakes. (Ultra)centrifugation techniques have thus far been the most investigated to sort GRMs following ultrasonication, shear mixing, ball milling, microfluidization, and wet-jet milling. It allows sorting by size and thickness. Inks formulated from GRM dispersions can be printed using a number of processes, from inkjet to screen printing. Each technique has specific rheological requirements, as well as geometrical constraints. The solvent choice is critical, not only for the GRM stability, but also in terms of optimizing printing on different substrates, such as glass, Si, plastic, paper, etc, all with different surface energies. Chemical modifications of such substrates is also a key step. Sections IV-VII are devoted to the growth of GRMs on various substrates and their processing after growth to place them on the surface of choice for specific applications. The substrate for graphene growth is a key determinant of the nature and quality of the resultant film. The lattice mismatch between graphene and substrate influences the resulting crystallinity. Growth on insulators, such as SiO2, typically results in films with small crystallites, whereas growth on the close-packed surfaces of metals yields highly crystalline films. Section IV outlines the growth of graphene on SiC substrates. This satisfies the requirements for electronic applications, with well-defined graphene-substrate interface, low trapped impurities and no need for transfer. It also allows graphene structures and devices to be measured directly on the growth substrate. The flatness of the substrate results in graphene with minimal strain and ripples on large areas, allowing spectroscopies and surface science to be performed. We also discuss the surface engineering by intercalation of the resulting graphene, its integration with Si-wafers and the production of nanostructures with the desired shape, with no need for patterning. Section V deals with chemical vapour deposition (CVD) onto various transition metals and on insulators. Growth on Ni results in graphitized polycrystalline films. While the thickness of these films can be optimized by controlling the deposition parameters, such as the type of hydrocarbon precursor and temperature, it is difficult to attain single layer graphene (SLG) across large areas, owing to the simultaneous nucleation/growth and solution/precipitation mechanisms. The differing characteristics of polycrystalline Ni films facilitate the growth of graphitic layers at different rates, resulting in regions with differing numbers of graphitic layers. High-quality films can be grown on Cu. Cu is available in a variety of shapes and forms, such as foils, bulks, foams, thin films on other materials and powders, making it attractive for industrial production of large area graphene films. The push to use CVD graphene in applications has also triggered a research line for the direct growth on insulators. The quality of the resulting films is lower than possible to date on metals, but enough, in terms of transmittance and resistivity, for many applications as described in section V. Transfer technologies are the focus of section VI. CVD synthesis of graphene on metals and bottom up molecular approaches require SLG to be transferred to the final target substrates. To have technological impact, the advances in production of high-quality large-area CVD graphene must be commensurate with those on transfer and placement on the final substrates. This is a prerequisite for most applications, such as touch panels, anticorrosion coatings, transparent electrodes and gas sensors etc. New strategies have improved the transferred graphene quality, making CVD graphene a feasible option for CMOS foundries. Methods based on complete etching of the metal substrate in suitable etchants, typically iron chloride, ammonium persulfate, or hydrogen chloride although reliable, are time- and resource-consuming, with damage to graphene and production of metal and etchant residues. Electrochemical delamination in a low-concentration aqueous solution is an alternative. In this case metallic substrates can be reused. Dry transfer is less detrimental for the SLG quality, enabling a deterministic transfer. There is a large range of layered materials (LMs) beyond graphite. Only few of them have been already exfoliated and fully characterized. Section VII deals with the growth of some of these materials. Amongst them, h-BN, transition metal tri- and di-chalcogenides are of paramount importance. The growth of h-BN is at present considered essential for the development of graphene in (opto) electronic applications, as h-BN is ideal as capping layer or substrate. The interesting optical and electronic properties of TMDs also require the development of scalable methods for their production. Large scale growth using chemical/physical vapour deposition or thermal assisted conversion has been thus far limited to a small set, such as h-BN or some TMDs. Heterostructures could also be directly grown. Section VIII discusses advances in GRM functionalization. A broad range of organic molecules can be anchored to the sp(2) basal plane by reductive functionalization. Negatively charged graphene can be prepared in liquid phase (e.g. via intercalation chemistry or electrochemically) and can react with electrophiles. This can be achieved both in dispersion or on substrate. The functional groups of GO can be further derivatized. Graphene can also be noncovalently functionalized, in particular with polycyclic aromatic hydrocarbons that assemble on the sp(2) carbon network by pi-pi stacking. In the liquid phase, this can enhance the colloidal stability of SLG/FLG. Approaches to achieve noncovalent on-substrate functionalization are also discussed, which can chemically dope graphene. Research efforts to derivatize CNMs are also summarized, as well as novel routes to selectively address defect sites. In dispersion, edges are the most dominant defects and can be covalently modified. This enhances colloidal stability without modifying the graphene basal plane. Basal plane point defects can also be modified, passivated and healed in ultra-high vacuum. The decoration of graphene with metal nanoparticles (NPs) has also received considerable attention, as it allows to exploit synergistic effects between NPs and graphene. Decoration can be either achieved chemically or in the gas phase. All LMs,
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| 2. |
- Barbieri, Paolo Nicola, et al.
(författare)
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Let young people join the legislative process. A Twitter based experiment on internships
- 2016
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Ingår i: Computers in Human Behavior. - : Elsevier BV. - 0747-5632. ; 60
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Tidskriftsartikel (refereegranskat)abstract
- This paper examines the possible effects of labour market institutional characteristics on young people's perceptions of their internship experiences as expressed on Twitter. By looking at these opinions (satisfaction versus dissatisfaction) in relation to certain features of internships as well as to the more general labour market regulatory framework, this project aims to give a voice to young people, enabling them (indirectly) to provide policy suggestions to law-makers. Furthermore, we propose a preview of a possible empirical model for data collection based on the manual coding of Tweets. By employing a Probit regression and Blinder–Oaxaca and Fairlie decompositions, we have tried to establish a link between the perceived evaluation of internships and the country where the internship is based, the latter being used as a proxy for the legal system. In all our tests we found that the country in which the internship is placed is the main factor in the positive or negative perception. We also find that the more difficult is to hire a young worker on a temporary basis the lower will be his valuation of the internship experience. Ultimately we propose the use of Twitter not only as a relevant research tool, but also as an instrument for bringing young people's needs to the attention of law-makers.
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| 3. |
- Carlsen, Esben Andreas, et al.
(författare)
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Peptide receptor radionuclide therapy in gastroenteropancreatic NEN G3 : a multicenter cohort study
- 2019
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Ingår i: Endocrine-Related Cancer. - : Bioscientifica. - 1351-0088 .- 1479-6821. ; 26:2, s. 227-239
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Tidskriftsartikel (refereegranskat)abstract
- Peptide receptor radionuclide therapy (PRRT) is an established treatment of metastatic neuroendocrine tumors grade 1-2 (G1-G2). However, its possible benefit in high-grade gastroenteropancreatic (GEP) neuroendocrine neoplasms (NEN G3) is largely unknown. We therefore aimed to assess the benefits and side effects of PRRT in patients with GEP NEN G3. We performed a retrospective cohort study at 12 centers to assess the efficacy and toxicity of PRRT in patients with GEP NEN G3. Outcomes were response rate, disease control rate, progression-free survival (PFS), overall survival (OS) and toxicity. We included 149 patients (primary tumor: pancreatic n = 89, gastrointestinal n = 34, unknown n = 26). PRRT was first-line (n = 30), second-line (n = 62) or later-line treatment (n = 57). Of 114 patients evaluated, 1% had complete response, 41% partial response, 38% stable disease and 20% progressive disease. Of 104 patients with documented progressive disease before PRRT, disease control rate was 69%. The total cohort had median PFS of 14 months and OS of 29 months. Ki-67 21-54% (n = 125) vs Ki-67 >= 55% (n = 23): PFS 16 vs 6 months (P < 0.001) and OS 31 vs 9 months (P < 0.001). Well (n = 60) vs poorly differentiated NEN (n = 62): PFS 19 vs 8 months (P < 0.001) and OS 44 vs 19 months (P < 0.001). Grade 3-4 hematological or renal toxicity occurred in 17% of patients. This large multicenter cohort of patients with GEP NEN G3 treated with PRRT demonstrates promising response rates, disease control rates, PFS and OS as well as toxicity in patients with mainly progressive disease. Based on these results, PRRT may be considered for patients with GEP NEN G3.
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| 4. |
- Elgendy, Mohamed, et al.
(författare)
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Dual modulation of MCL-1 and mTOR determines the response to sunitinib
- 2017
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Ingår i: Journal of Clinical Investigation. - 0021-9738 .- 1558-8238. ; 127:1, s. 153-168
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Tidskriftsartikel (refereegranskat)abstract
- Most patients who initially respond to treatment with the multi-tyrosine kinase inhibitor sunitinib eventually relapse. Therefore, developing a deeper understanding of the contribution of sunitinib's numerous targets to the clinical response or to resistance is crucial. Here, we have shown that cancer cells respond to clinically relevant doses of sunitinib by enhancing the stability of the antiapoptotic protein MCL-1 and inducing mTORC1 signaling, thus evoking little cytotoxicity. Inhibition of MCL-1 or mTORC1 signaling sensitized cells to clinically relevant doses of sunitinib in vitro and was synergistic with sunitinib in impairing tumor growth in vivo, indicating that these responses are triggered as prosurvival mechanisms that enable cells to tolerate the cytotoxic effects of sunitinib. Furthermore, higher doses of sunitinib were cytotoxic, triggered a decline in MCL-1 levels, and inhibited mTORC1 signaling. Mechanistically, we determined that sunitinib modulates MCL-1 stability by affecting its proteasomal degradation. Dual modulation of MCL-1 stability at different dose ranges of sunitinib was due to differential effects on ERK and GSK3 beta activity, and the latter also accounted for dual modulation of mTORC1 activity. Finally, comparison of patient samples prior to and following sunitinib treatment suggested that increases in MCL-1 levels and mTORC1 activity correlate with resistance to sunitinib in patients.
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| 5. |
- Fazio, Nicola, et al.
(författare)
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Everolimus Plus Octreotide Long-Acting Repeatable in Patients With Advanced Lung Neuroendocrine Tumors Analysis of the Phase 3, Randomized, Placebo-Controlled RADIANT-2 Study
- 2013
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Ingår i: Chest. - : Elsevier BV. - 0012-3692 .- 1931-3543. ; 143:4, s. 955-962
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Tidskriftsartikel (refereegranskat)abstract
- Background: The incidence of neuroendocrine tumors (NETs) has increased approximately fivefold since the 1980s. A similar increase in the incidence of lung NETs has been reported, but therapy has not been optimized. Methods: This exploratory subanalysis evaluated the efficacy and safety of everolimus plus octreotide long-acting repeatable (LAIR) in a cohort of patients with low- to intermediate-grade advanced lung NET from the phase 3, randomized, placebo-controlled RADIANT-2 (RAD001 in Advanced Neuroendocrine Tumors) study. The primary end point was progression-free survival (PFS). Secondary end points included objective response rate, overall survival, change from baseline in biomarker levels, and safety outcomes. Results: Patients were randomly assigned to everolimus plus octreotide LAIR (n = 33) or placebo plus octreotide LAIR (n = 11). Median PFS was 13.63 months in the everolimus plus octreotide LAIR arm compared with 5.59, months in the placebo plus octreotide LAIR arm (relative risk for progression: HR, 0.72; 95% CI, 0.31-1.68; P = .228). More patients receiving everolimus plus octreotide LAR (67%) experienced minor tumor shrinkage (not partial response as per RECIST [Response Evaluation Criteria in Solid Tumors]) than those receiving placebo plus octreotide LAIR (27%). Most frequently reported adverse events (AEs) included stomatitis, rash, diarrhea, and asthenia. This was consistent with the overall RADIANT-2 trial and the safety profile of everolimus. Conclusions: This exploratory subgroup analysis of the RADIANT-2 trial indicates that in patients with advanced lung NET, the addition of everolimus to octreotide LAIR improves median PFS by 2.4-fold compared with placebo plus octreotide LAIR. These clinically significant observations support the continued evaluation of everolimus treatment regimens in this patient population. Trial registry: ClinicalTrials.gov; No.: NCT00412061; PRL: www.clinicaltrials.gov CHEST 2013; 143(4):955-962
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| 6. |
- Garcia-Carbonero, Rocio, et al.
(författare)
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ENETS Consensus Guidelines for the Standards of Care in Neuroendocrine Neoplasms : Systemic Therapy - Chemotherapy
- 2017
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Ingår i: Neuroendocrinology. - : S. Karger AG. - 0028-3835 .- 1423-0194. ; 105:3, s. 281-294
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Tidskriftsartikel (refereegranskat)abstract
- Systemic chemotherapy is indicated in progressive or bulky advanced pancreatic neuroendocrine tumors (NETs) and in grade 3 (G3) neuroendocrine neoplasms (NENs) as per ENETS guidelines. Chemotherapy may be considered in NETs of other sites (lung, thymus, stomach, colon, and rectum) under certain conditions (e.g., when Ki-67 is at a high level [upper G2 range], in rapidly progressive disease and/or after failure of other therapies, or if somatostatin receptor imaging is negative). An ENETS Consensus Conference was held in Antibes (2015) to elaborate guidelines on the standards of care of different diagnostic procedures and therapeutic interventions in NENs. This article provides guidance on chemotherapy including therapeutic indications, dosing schedules, adverse events (including prevention and management), drug interactions, and evaluation of treatment effect for the chemotherapy agents most commonly used in NENs (streptozocin, dacarbazine, fluoropyrimidines, platinum compounds, etoposide, and irinotecan).
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| 7. |
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| 8. |
- Grimaldi, Franco, et al.
(författare)
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Assessment of Response to Treatment and Follow-Up in Gastroenteropancreatic Neuroendocrine Neoplasms
- 2018
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Ingår i: Endocrine, Metabolic & Immune Disorders - Drug Targets. - : Bentham Science. - 1871-5303 .- 2212-3873. ; 18:5, s. 419-449
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Tidskriftsartikel (refereegranskat)abstract
- Well-established criteria for evaluating the response to treatment and the appropriate follow-up of individual patients are critical in clinical oncology. The current evidence-based data on these issues in terms of the management of gastroenteropancreatic (GEP) neuroendocrine neoplasms (NEN) are unfortunately limited. This document by the Italian Association of Clinical Endocrinologists (AME) on the criteria for the follow-up of GEP-NEN patients is aimed at providing comprehensive recommendations for everyday clinical practice based on both the best available evidence and the combined opinion of an interdisciplinary panel of experts. The initial risk stratification of patients with NENs should be performed according to the grading, staging and functional status of the neoplasm and the presence of an inherited syndrome. The evaluation of response to the initial treatment, and to the subsequent therapies for disease progression or recurrence, should be based on a cost-effective, risk-effective and timely use of the appropriate diagnostic resources. A multidisciplinary evaluation of the response to the treatment is strongly recommended and, at every step in the follow-up, it is mandatory to assess the disease state and the patient performance status, comorbidities, and recent clinical evolution. Local expertise, available technical resources and the patient preferences should always be evaluated while planning the individual clinical management of GEP-NENs.
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| 9. |
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| 10. |
- Guzzi, Nicola, et al.
(författare)
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Pseudouridine-modified tRNA fragments repress aberrant protein synthesis and predict leukaemic progression in myelodysplastic syndrome
- 2022
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Ingår i: Nature Cell Biology. - : Springer Science and Business Media LLC. - 1465-7392 .- 1476-4679. ; 24:3, s. 299-306
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Tidskriftsartikel (refereegranskat)abstract
- Transfer RNA-derived fragments (tRFs) are emerging small noncoding RNAs that, although commonly altered in cancer, have poorly defined roles in tumorigenesis1. Here we show that pseudouridylation (Ψ) of a stem cell-enriched tRF subtype2, mini tRFs containing a 5′ terminal oligoguanine (mTOG), selectively inhibits aberrant protein synthesis programmes, thereby promoting engraftment and differentiation of haematopoietic stem and progenitor cells (HSPCs) in patients with myelodysplastic syndrome (MDS). Building on evidence that mTOG-Ψ targets polyadenylate-binding protein cytoplasmic 1 (PABPC1), we employed isotope exchange proteomics to reveal critical interactions between mTOG and functional RNA-recognition motif (RRM) domains of PABPC1. Mechanistically, this hinders the recruitment of translational co-activator PABPC1-interacting protein 1 (PAIP1)3 and strongly represses the translation of transcripts sharing pyrimidine-enriched sequences (PES) at the 5′ untranslated region (UTR), including 5′ terminal oligopyrimidine tracts (TOP) that encode protein machinery components and are frequently altered in cancer4. Significantly, mTOG dysregulation leads to aberrantly increased translation of 5′ PES messenger RNA (mRNA) in malignant MDS-HSPCs and is clinically associated with leukaemic transformation and reduced patient survival. These findings define a critical role for tRFs and Ψ in difficult-to-treat subsets of MDS characterized by high risk of progression to acute myeloid leukaemia (AML).
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