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Correction for 'Magnetic aerogels from FePt and CoPt3 directly from organic solution' by L. Schoske et al., Nanoscale, 2024, 16, 4229-4238, https://doi.org/10.1039/D3NR05892A.
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Luminophore stained micro- and nanobeads made from organic polymers like polystyrene (PS) are broadly used in the life and material sciences as luminescent reporters, for bead-based assays, sensor arrays, printable barcodes, security inks, and the calibration of fluorescence microscopes and flow cytometers. Initially mostly prepared with organic dyes, meanwhile luminescent core/shell nanoparticles (NPs) like spherical semiconductor quantum dots (QDs) are increasingly employed for bead encoding. This is related to their narrower emission spectra, tuneability of emission color, broad wavelength excitability, and better photostability. However, correlations between particle architecture, morphology, and photoluminescence (PL) of the luminescent nanocrystals used for encoding and the optical properties of the NP-stained beads have been rarely explored. This encouraged us to perform a screening study on the incorporation of different types of luminescent core/shell semiconductor nanocrystals into polymer microparticles (PMPs) by a radical-induced polymerization reaction. Nanocrystals explored include CdSe/CdS QDs of varying CdS shell thickness, a CdSe/ZnS core/shell QD, CdSe/CdS quantum rods (QRs), and CdSe/CdS nanoplatelets (NPLs). Thereby, we focused on the applicability of these NPs for the polymerization synthesis approach used and quantified the preservation of the initial NP luminescence. The spectroscopic characterization of the resulting PMPs revealed the successful staining of the PMPs with luminescent CdSe/CdS QDs and CdSe/CdS NPLs. In contrast, usage of CdSe/CdS QRs and CdSe QDs with a ZnS shell did not yield luminescent PMPs. The results of this study provide new insights into structure-property relationships between NP stained PMPs and the initial luminescent NPs applied for staining and underline the importance of such studies for the performance optimization of NP-stained beads.
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Here the synthesis of magnetic aerogels from iron platinum and cobalt platinum nanoparticles is presented. The use of hydrazine monohydrate as destabilizing agent triggers the gelation directly from organic solution, and therefore a phase transfer to aqueous media prior to the gelation is not necessary. The aerogels were characterized through Transmission Electron Microscopy, Scanning Electron Microscopy, Powder X-Ray Diffraction Analysis and Argon Physisorption measurements to prove the formation of a porous network and define their compositions. Additionally, magnetization measurements in terms of hysteresis cycles at 5 K and 300 K (M-H-curves) as well as zero field cooled-field cooled measurements (ZFC-FC measurements) of the dried colloids and the respective xero- and aerogels were performed, in order to analyze the influence of the gelation process and the network structure on the magnetic properties.
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Surface-functionalized polymer beads encoded with molecular luminophores and nanocrystalline emitters such as semiconductor nanocrystals, often referred to as quantum dots (QDs), or magnetic nanoparticles are broadly used in the life sciences as reporters and carrier beads. Many of these applications require a profound knowledge of the chemical nature and total number of their surface functional groups (FGs), that control bead charge, colloidal stability, hydrophobicity, and the interaction with the environment and biological systems. For bioanalytical applications, also the number of groups accessible for the subsequent functionalization with, e.g., biomolecules or targeting ligands is relevant. In this study, we explore the influence of QD encoding on the amount of carboxylic acid (COOH) surface FGs of 2 µm polystyrene microparticles (PSMPs). This is done for frequently employed oleic acid and oleylamine stabilized, luminescent core/shell CdSe QDs and two commonly used encoding procedures. This included QD addition during bead formation by a thermally induced polymerization reaction and a post synthetic swelling procedure. The accessible number of COOH groups on the surface of QD-encoded and pristine beads was quantified by two colorimetric assays, utilizing differently sized reporters and electrostatic and covalent interactions. The results were compared to the total number of FGs obtained by a conductometric titration and Fourier transform infrared spectroscopy (FTIR). In addition, a comparison of the impact of QD and dye encoding on the bead surface chemistry was performed. Our results demonstrate the influence of QD encoding and the QD-encoding strategy on the number of surface FG that is ascribed to an interaction of the QDs with the carboxylic acid groups on the bead surface. These findings are of considerable relevance for applications of nanoparticle-encoded beads and safe-by-design concepts for nanomaterials.
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Luminescence-encoded microbeads are important tools for many applications in the life and material sciences that utilize luminescence detection as well as multiplexing and barcoding strategies. The preparation of such beads often involves the staining of premanufactured beads with molecular luminophores using simple swelling procedures or surface functionalization with layer-by-layer (LbL) techniques. Alternatively, these luminophores are sterically incorporated during the polymerization reaction yielding the polymer beads. The favorable optical properties of semiconductor quantum dots (QDs), which present broadly excitable, size-tunable, narrow emission bands and low photobleaching sensitivity, triggered the preparation of beads stained with QDs. However, the colloidal nature and the surface chemistry of these QDs, which largely controls their luminescence properties, introduce new challenges to bead encoding that have been barely systematically assessed. To establish a straightforward approach for the bead encoding with QDs with minimized loss in luminescence, we systematically assessed the incorporation of oleic acid/oleylamine-stabilized CdSe/CdS-core/shell-QDs into 0.5-2.5 µm-sized polystyrene (PS) microspheres by a simple dispersion polymerization synthesis that was first optimized with the organic dye Nile Red. Parameters addressed for the preparation of luminophore-encoded beads include the use of a polymer-compatible ligand such as benzyldimethyloctadecylammonium chloride (OBDAC) for the QDs, and crosslinking to prevent luminophore leakage. The physico-chemical and optical properties of the resulting beads were investigated with electron microscopy, dynamic light scattering, optical spectroscopy, and fluorescence microscopy. Particle size distribution, fluorescence quantum yield of the encapsulated QDs, and QD leaking stability were used as measures for bead quality. The derived optimized bead encoding procedure enables the reproducible preparation of bright PS microbeads encoded with organic dyes as well as with CdSe/CdS-QDs. Although these beads show a reduced photoluminescence quantum yield compared to the initially very strongly luminescent QDs, with values of about 35%, their photoluminescence quantum yield is nevertheless still moderate.
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Pontos Quânticos , Corantes , Luminescência , Microesferas , Polimerização , Poliestirenos/química , Pontos Quânticos/química , SemicondutoresRESUMO
The assembly of CdSe/CdS dot/rod nanocrystals (NCs) with variable length of ZnS tips into aerogel networks is presented. To this end, a partial region selective cation exchange procedure is performed replacing Cd by Zn starting at the NC tip. The produced aerogel networks are investigated structurally and optically. The networks of tip-to-tip connected NCs have an intricate band structure with holes confined to the CdSe cores while electrons are delocalized within the CdS also within connected building blocks. However, the ZnS tips act as a barrier of variable length and strength between the NC building blocks partly confining the electrons. This results in NC based aerogel networks with tunable strength of coupling between building blocks.
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BACKGROUND AND OBJECTIVES: Disparities in type 2 diabetes mellitus (diabetes) represent an ongoing public health challenge. Black older adults are at high risk of diabetes and diabetes' complications. Diet, physical activity, and medication can control these risks, yet disease rates remain elevated. Utilizing an intersectionality framework, we seek to extend understanding of the social dimensions of diabetes through an examination of the diabetes self-care process from the perspective of Black older adults. RESEARCH DESIGN AND METHODS: This project involved a thematic analysis of diabetes illness narrative interviews with Black participants (N = 41) in our National Institute on Aging-funded study of diabetes. In a narrative approach, the participant communicates the significance of actions and events. RESULTS: The findings suggest that diabetes self-care involves interconnected struggles across four domains of care: (1) multimorbidity management, (2) financial well-being, (3) family support, and (4) formal health care. DISCUSSION AND IMPLICATIONS: Black older adult self-care reflects an active process of pursuing meaningful social goals and critical health needs. An intersectional framework, however, reveals the ongoing histories of inequity that shape this process. Further intervention to address the racist policies and practices found in Black older adults' communities and clinical care is needed to make true progress on diabetes disparities.
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Diabetes Mellitus Tipo 2 , Autocuidado , Idoso , Diabetes Mellitus Tipo 2/terapia , Exercício Físico , Humanos , Estudos Longitudinais , MultimorbidadeRESUMO
Folate, a cofactor for the supply of one-carbon groups, is required by epigenetic processes to regulate cell lineage determination during development. The intake of folic acid (FA), the synthetic form of folate, has increased significantly over the past decade, but the effects of high periconceptional FA intake on cell lineage determination in the early embryo remains unknown. Here, we investigated the effect of maternal high FA (HFA) intake on blastocyst development and expression of key regulatory genes. C57BL/6 adult female mice were fed either Control diet (1 mg FA) for 4 weeks before conception and during the preimplantation period (Con-Con); Control diet for 4 weeks preconception, followed by HFA (5 mg FA) diet during preimplantation (Con-HFA); or HFA diet for 4 weeks preconception and during preimplantation (HFA-HFA). At E3.5, blastocyst cell number, protein, and mRNA expression were measured. In HFA-HFA blastocysts, trophectoderm cell numbers and expression of CDX2, Oct-4, and Nanog were reduced compared with Con-Con blastocysts; Con-HFA blastocysts showed lower CDX2 and Oct-4 expression than Con-Con blastocysts. These findings suggest periconceptional HFA intake induces changes in key regulators of embryo morphogenesis with potential implications for subsequent development.
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Blastocisto/metabolismo , Linhagem da Célula/efeitos dos fármacos , Ingestão de Alimentos , Fertilização/efeitos dos fármacos , Ácido Fólico/administração & dosagem , Regulação da Expressão Gênica no Desenvolvimento/efeitos dos fármacos , Expressão Gênica/efeitos dos fármacos , Genes Reguladores/efeitos dos fármacos , Complexo Vitamínico B/administração & dosagem , Animais , Fator de Transcrição CDX2/metabolismo , Desenvolvimento Embrionário/efeitos dos fármacos , Epigênese Genética , Feminino , Fertilização/genética , Ácido Fólico/sangue , Camundongos , Camundongos Endogâmicos C57BL , Proteína Homeobox Nanog/metabolismo , Fator 3 de Transcrição de Octâmero/metabolismo , Gravidez , Transdução de Sinais/efeitos dos fármacos , Complexo Vitamínico B/sangueRESUMO
Femoral component loosening is a rare but severe complication in total knee arthroplasty. Former studies have repeatedly demonstrated radiolucent lines behind the ventral and dorsal anchoring shields of the femoral components, which has led us to investigate this matter further. Therefore, three different cementing techniques were tested in a group of nine Sawbone samples each. These differed in the amount of cement applied on the femoral component as well as in the pressure application. Computed tomography was performed to evaluate and classify the cement penetration into the bone adjacent to the prosthesis according to the zones defined by the Knee Society scoring system. The results show significantly deeper cement penetration in all zones when a pressurizer is used. In the other two groups, no significant difference in the dorsal bevel cement penetration was noted. Additionally, no difference in ventral and dorsal cement penetrations (Zones 1 and 4) was delineated. In contrast, there was a significant difference in both the ventral bevel (Zone 2) as well as the distal anchoring surface (Zones 5-7). The use of a pressurizer results in greater cement penetration into all anchoring areas. Completely covering the component back surface results in a significantly higher penetration, which is mainly due to differences in volume. These data show significantly improved cementation results when using a pressurizer. Whether this improves the biomechanical properties and ultimately the revision rate requires further investigation.
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Artroplastia do Joelho/efeitos adversos , Artroplastia do Joelho/métodos , Cimentação/efeitos adversos , Fêmur/cirurgia , Articulação do Joelho/cirurgia , Fenômenos Biomecânicos , Cimentos Ósseos , Cimentação/métodos , Fêmur/diagnóstico por imagem , Humanos , Articulação do Joelho/diagnóstico por imagem , Modelos Anatômicos , Falha de Prótese , Tomografia Computadorizada por Raios XRESUMO
We report a novel plastic deformation mechanism of bulk metallic glass composites (BMGCs) containing metastable ß-Ti dendrites. Plastic deformation of the BMGCs beyond the ultimate tensile strength is mediated by cooperative shear events, which comprise a shear band in the glassy matrix and a continuous ω-Ti band with a thickness of â¼10 nm in the ß-Ti dendrite. The cooperative shear leads to serrated shear avalanches. The formation of narrow ω-Ti bands is caused by high local strain rates during the cooperative shear. The cooperative shear mechanism enriches the deformation mechanisms of BMGCs and also deepens the understanding of ω-Ti formation.
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An exceptional combination of low Young's modulus (E ~68 GPa) and high flow strength (σf ~1 GPa) was achieved for a consolidated ß-Ti-based metastable Ti-35Nb-7Zr-5Ta (TNZT) alloy subjected to room temperature high-pressure torsion (HPT). The mechanical properties of the alloy were studied by quasistatic nanoindentation tests at different strain rates, where a reduction in Young's modulus E ~73 GPa (NHPT10) and E ~68 GPa (NHPT40) is observed together with an increase in plastic deformability (or HPT rotations). The microstructure evolution with increasing shear strain has been investigated. The stabilized bcc ß-Ti phase with homogeneous nanostructure distribution was observed leading to a low Young's modulus. Severe straining causes a uniform hardness distribution without any noticeable change in the strength of the material. This study may be useful for developing excellent removable implant materials.
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Ligas , Titânio , Módulo de Elasticidade , Dureza , Próteses e ImplantesRESUMO
With the discovery of bulk metallic glasses (BMGs), there has been considerable interest in understanding their mechanical behavior. In spite of these previous observations on the relation between plastic deformation of metallic glasses and their diffusion behavior, a detailed understanding on the diffusion of BMGs is still unexplored. We evaluated the contribution of deformation-induced structural transformations (elastic, anelastic, viscoplastic or viscoelastic responsive and plastic strain) on the diffusion of Zr-based bulk metallic glasses in as-cast, elastostatically stressed and plastically deformed states. Experimental investigations of the diffusion process and the elemental distributions in the glassy alloy were performed following plastic deformation by multiple cold rolling and elastostatic cyclic compression, respectively. We compared the vacancy model and the transition state model to verify the diffusion mechanism in the deformed bulk metallic glass. The diffusion of tracer atoms, i.e., Fe, in the bulk metallic glass is affected by viscoelastic responsive strain governing the transition-state model. In contrast, the diffusion of constituent atoms, i.e., Ti, Zr, in the bulk metallic glass is dominantly affected by plastic strain governing the vacancy model. The results reveal that the diffusion behavior of bulk glassy alloys can be changed by variation of the constituent elements and applying different strain modes upon deformation.
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BACKGROUND: Inflammatory bowel disease (IBD), comprising Crohn disease and ulcerative colitis, affects 1 to 3 million people in the United States. Telemedicine has shown promise in IBD. The objective of this study, telemedicine for patients with IBD (TELE-IBD), was to compare disease activity and quality of life (QoL) in a 1-year randomized clinical trial of IBD patients receiving telemedicine versus standard care. Treatment groups experienced improvements in disease activity and QoL, but there were no significant differences between groups. Study adherence to the text-based intervention was less than 80%, the targeted goal. OBJECTIVE: To understand adherence to remote monitoring, the goal of this qualitative assessment was to obtain TELE-IBD trial participants' perceptions, including their recommendations for future monitoring. METHODS: In this study, patients attending 3 tertiary referral centers with worsening IBD symptoms in the previous 2 years were eligible for randomization to remote monitoring via SMS text messages (short message service, SMS) every other week, weekly, or standard care. Participants (n=348) were evenly enrolled in the treatment groups, and 259 (74.4%) completed the study. For this study, a purposive sample of adherent (N=15) and nonadherent (N=14) patients was drawn from the TELE-IBD trial population. Adherence was defined as the completion of 80% (278/348) or more of the weekly or every other week self-assessments. Semistructured interviews conducted by phone surveyed (1) the strengths and benefits of TELE-IBD, (2) challenges associated with using TELE-IBD, and (3) how to improve the TELE-IBD intervention. Interviews were recorded, professionally transcribed, and coded based on a priori concepts and emergent themes with the aid of ATLAS.ti, version.7 qualitative data analysis software. RESULTS: Participants' discussions centered on 3 elements of the intervention: (1) self-assessment questions, (2) action plans, and (3) educational messages. Participants also commented on text-based platform, depression and adherence, TELE-IBD system in place of office visit, and their recommendations for future TELE-IBD systems. Adherent and nonadherent participants prefer a flexible system that is personalized, including targeted education messages, and they perceive the intervention as effective in facilitating IBD self-management. CONCLUSIONS: Participants identified clear benefits to the TELE-IBD system, including obtaining a better understanding of the disease process, monitoring their symptoms, and feeling connected to their health care provider. Participants' perceptions obtained in this qualitative study will assist in improving the TELE-IBD system to be more responsive to patients with IBD.
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Doenças Inflamatórias Intestinais/terapia , Qualidade de Vida/psicologia , Telemedicina/métodos , Feminino , Humanos , Masculino , Percepção , Pesquisa Qualitativa , Inquéritos e QuestionáriosRESUMO
The effect of elevated CO2 concentration on leaves of black elder (Sambucus nigra) was investigated based on leaf gas exchange, chlorophyll content as well as on the analysis of the underlying metabolite profile of the fruits. The measurements were carried out once a month over a period of time of 4 months. The CO2 uptake rate, the transpiration rate and stomatal conductance were significantly higher in plants under ambient CO2, in comparison to plants grown under elevated CO2 concentrations. On the other hand, at the initial phase of the experiments, the photosynthesis rate was higher in CO2 loaded plants compared to plants grown under normal conditions. Remarkably, after about one month a habituation effect could be observed leading to a decrease of the photosynthetic efficiency approaching again the normal level. To understand the observed effects on a molecular level, non-targeted fingerprinting analysis was performed on the ripe elder berries using LC-qToF-ESI-MS(/MS). Differences in the composition of various phenols, triglycerides and PC (36:5) as well as a stigmasterole-derivate could be detected. In contrast, central metabolic pathways such as photosynthesis, the tricarboxylic acid cycle as well as the biosynthesis of essential amino acids obviously are not considerably affected.
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Dióxido de Carbono/fisiologia , Frutas/química , Sambucus nigra/fisiologia , Cromatografia Líquida de Alta Pressão , Mudança Climática , Metabolismo dos Lipídeos , Fenóis/metabolismo , Sambucus nigra/química , Estações do Ano , Espectrometria de Massas por Ionização por ElectrosprayRESUMO
AIMS: Late in-stent restenosis (ISR) has become increasingly important, in particular due to neo-atherosclerosis. CCTA is a highly sensitive method for detecting coronary plaques. Its diagnostic accuracy regarding ISR is controversial. Stent artifacts can impede image quality, but recent developments in CT-technology may help to overcome some of these problems and allow for improved diagnostic accuracy. METHODS: Consecutive patients after previous coronary revascularization who had stable symptoms or signs of possible disease progression were examined using a third-generation dual-source CT scanner. After the scan, patients were followed for clinical events (MACE) over a mean of 399 days. Patients with high-grade stenoses were referred for invasive coronary angiography (ICA), unclear findings were further evaluated either by ICA or functional testing. RESULTS: Overall, 226 patients were included. A total of 457 stents were evaluated (2.0 ± 1.4 per patient). Mean stent diameter was 2.9 ± 0.45 mm. In 61%, a high-pitch protocol was employed. Mean dose-length product (DLP) of CCTA was 159.2 mGy cm, corresponding to 2.2 mSv using a conversion factor of k = 0.014. Mean amount of contrast agent was 58.3 ± 12.5 ml. In 145 patients (64%), CCTA was negative. In this group, one MACE occurred (acute coronary syndrome) during follow-up in a patient who had also undergone unremarkable ICA. In 23 patients (10%), CCTA detected 28 ISR which were confirmed and treated by ICA (true positive). In 27 patients (12%), ISR was suspected by CCTA but excluded by ICA (false positive), 30 patients (13%) had unclear findings and normal non-invasive tests. No MACE occurred during follow-up in these patients. One patient was misclassified in CCTA as having intermediate and not high-grade ISR who underwent revascularization within 3 months. Eleven patients (5%) were lost to follow-up. During follow-up, eight patients had myocardial infarctions due to five ISRs and three de novo lesions. No patient died. In cases with unclear or false-positive findings, the amount of stents was significantly higher, stents were smaller and patients had a higher BMI. CONCLUSION: In almost two-thirds of symptomatic patients with previous coronary stent implantation, ISR could be ruled out by CCTA. 10% of patients had definite ISR. The rate of false-negative findings was low (< 1%), whereas the rate of false positive or inconclusive findings was 25%, leading to invasive rule-out of ISR by ICA in 12%. CCTA appears valuable as a tool for safely excluding ISR. It might help to avoid invasive diagnostic procedures. Further analyses are warranted, in particular regarding the influence of stent dimensions and the total amount of stents in a patient.
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Angiografia por Tomografia Computadorizada/métodos , Angiografia Coronária/métodos , Doença da Artéria Coronariana/cirurgia , Reestenose Coronária/diagnóstico , Tomografia Computadorizada Multidetectores/métodos , Intervenção Coronária Percutânea/efeitos adversos , Stents/efeitos adversos , Idoso , Doença da Artéria Coronariana/diagnóstico , Feminino , Seguimentos , Humanos , Masculino , Falha de Prótese , Reprodutibilidade dos Testes , Estudos RetrospectivosRESUMO
BACKGROUND: Contemporary treatment of type 2 diabetes mellitus (hereafter diabetes) heavily emphasizes "diabetes control," largely defined by measurable blood glucose parameters. Little is known about how people living with the condition themselves define diabetes control within the lived experience of their disease. METHODS: As part of a qualitative study investigating the subjective construction of diabetes, 83 in-depth interviews were conducted with African American and non-Hispanic white older adults. Using content analysis, 4237 pages of narrative data were analyzed to explore how informants conceptualized diabetes control. FINDINGS: Four themes emerged from the data, describing varied understandings of diabetes control: (a) blood sugar regulation, (b) practicable treatment adherence, (c) bodily experience, and (d) degree of pharmaceutical need. Findings demonstrate that among persons with diabetes, the term diabetes control is multifaceted. CONCLUSION: While clinical guidelines have established target blood glucose parameters as the standard indicator of diabetes control, persons with diabetes conveyed varied and diverse meanings situated within personal experiences. To foster empathetic and collaborative care, health-care providers tending to this population may consider integrating the emergent themes into communicative and treatment approaches.
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A prerequisite to utilize the full potential of structural heterogeneities for improving the room-temperature plastic deformation of bulk metallic glasses (BMGs) is to understand their interaction with the mechanism of shear band formation and propagation. This task requires the ability to artificially create heterogeneous microstructures with controlled morphology and orientation. Here, we analyze the effect of the designed heterogeneities generated by imprinting on the tensile mechanical behavior of the Zr52.5Ti5Cu18Ni14.5Al10 BMG by using experimental and computational methods. The imprinted material is elastically heterogeneous and displays anisotropic mechanical properties: strength and ductility increase with increasing the loading angle between imprints and tensile direction. This behavior occurs through shear band branching and their progressive rotation. Molecular dynamics and finite element simulations indicate that shear band branching and rotation originates at the interface between the heterogeneities, where the characteristic atomistic mechanism responsible for shear banding in a homogeneous glass is perturbed.
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One of the most significant objectives in the field of nanotechnology is the transfer of specific properties of smaller nanoparticle building blocks into larger units. In this way, nanoscopic properties can be linked to the macroscopic addressability of larger systems. Such systems might find applications in fields like photoelectrochemical sensing or solar energy harvesting. Our work reports on the novel synthesis of hybrid semiconductor/polymer fibres, which are based on stacks of 4 monolayer (ML) thick CdSe nanoplatelets (NPLs) encapsulated into a polymer shell. The polymer encapsulation not only enables the water transfer of the NPL stacks but also allows the preparation of photoelectrodes by linking the fibres to surface modified indium tin oxide (ITO) glass slides. By applying electrochemical techniques like intensity modulated photocurrent spectroscopy (IMPS), it was possible to prove the motion of charge carriers inside the nanoplatelet stacks and by this the electronic addressibility of them.
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The unparalleled shaping ability of bulk metallic glasses can revolutionize commercial products having multi-length scale features with a processing time of several minutes. Despite the widespread shaping ability of these polymer-like multicomponent alloys, thermoplastic forming (TPF) can severely degrade the intrinsic properties, particularly when complex stress states are activated. The present work emphasizes the importance of elastostatic loading (ESL) which not only fully reverses deteriorated room temperature plasticity originating under TPF or post-cryostatic conditions, but also activates a rejuvenation mechanism by rendering an extended resistance against strain softening. Furthermore, the reduction in the supercooled liquid region and crystallization enthalpy measured by differential scanning calorimetry are found to be temporary, and can be fully reversed to the initial condition. HRTEM imaging of the samples are performed with an imaging spherical aberration corrector. Individual nanobeam diffraction patterns obtained by the fluctuation electron microscopy (FEM) measurements are acquired using a scanning transmission electron microscope with a probe size of 1.2 nm from a 10 × 10 raster, yielding 100 diffraction patterns. The normalized variance of a series of nanodiffraction patterns of the post-elastostatically loaded sample reveals a height decrease in the first broad peak of normalized intensity variance V(k) suggesting modifications in the medium-range structural order which in turn dramatically restores the mechanical and thermal properties. Overall, the combination of TPF and post-ESL treatment in advanced glassy metals can open a new avenue for ultra-high mechanical and thermal performance micro- and nanomechanical devices for biosensors, MOSFETs and robotics.
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Strain hardening, originating from defects such as the dislocation, avails conventional metals of high engineering reliability in applications. However, the hardenability of metallic glass is a long-standing concern due to the lack of similar defects. In this work, we carefully examine the stress-strain relationship in three bulk monolithic metallic glasses. The results show that hardening is surely available in metallic glasses if the effective load-bearing area is considered instantly. The hardening is proposed to result from the remelting and ensuing solidification of the shear-band material under a hydrostatic pressure imposed by the normal stress during the shear banding event. This applied-pressure quenching densifies the metallic glass by discharging the free volume. On the other hand, as validated by molecular dynamics simulations, the pressure promotes the icosahedral short-range order. The densification and icosahedral clusters both contribute to the increase of the shear strength and therefore the hardening in metallic glasses.