Gas Sensing Properties of PLD Grown 2D SnS Film: Effect of Film Thickness, Metal Nanoparticle Decoration, and In Situ KPFM Investigation.

This study employs novel growth methodologies and surface sensitization with metal nanoparticles to enhance and manipulate gas sensing behavior of two-dimensional (2D)SnS film. Growth of SnS films is optimized by varying substrate temperature and laser pulses during pulsed laser deposition (PLD). Thereafter, palladium (Pd), gold (Au), and silver (Ag) nanoparticles are decorated on as-grown film using gas-phase synthesis techniques. X-ray diffraction (XRD), Raman spectroscopy, and Field-emission scanning electron microscopy (FESEM) elucidate the growth evolution of SnS and the effect of nanoparticle decoration. X-ray photoelectron spectroscopy (XPS) analyses the chemical state and composition. Pristine SnS, Ag, and Au decorated SnS films are sensitive and selective toward NO2 at room temperature (RT). Ag nanoparticle increases the response of pristine SnS from 48 to 138% toward 2 ppm NO2, which indicates electronic and chemical sensitization effect of Ag. Pd decoration on SnS tunes its selectivity toward H2 gas with a response of 55% toward 70 ppm H2 and limit of detection (LOD) < 1 ppm. In situ Kelvin probe force microscopy (KPFM) maps the work function changes, revealing catalytic effect of Ag toward NO2 in Ag-decorated SnS and direct charge transfer between Pd and SnS during H2 exposure in Pd-decorated SnS.

Racial disparities in pre-operative pain, function and disease activity for patients with rheumatoid arthritis undergoing Total knee or Total hip Arthroplasty: a New York based study.

BACKGROUND: Black and Hispanic patients with osteoarthritis have more pain and worse function than Whites at the time of arthroplasty. Whether this is true for patients with rheumatoid arthritis (RA) is unknown. METHODS: This cross-sectional study used data on RA patients acquired between October 2013 and November 2018 prior to elective total knee (TKA) or hip arthroplasty (THA). Pain, function, and disease activity were assessed using the visual analogue scale (VAS), the Multidimensional Health Assessment Questionnaire (MDHAQ), and the Disease Activity Score (DAS28-ESR). We linked the cases to census tracts using geocoding to determine the community poverty level. Race, education, income, insurance and medications were collected via self-report. Using multivariable linear and logistic models we examined whether minority status predicted pain, function and RA disease activity at the time of arthroplasty. RESULTS: Thirty seven (23%) of the 164 patients were Black or Hispanic (minorities). The MDHAQ and DAS28-ESR were not significantly worse while VAS pain score was significantly worse in minority patients (p = 0.03). There was no significant difference in education between the groups. Insurance varied significantly; 29% of minority patients had Medicaid vs. 0% of Whites (p < 0.0001). In the multivariable analyses minority status was not significantly associated with DAS28-ESR [p = 0.66], MDHAQ [p = 0.26], or VAS pain [p = 0.18]. CONCLUSIONS: For Black and/or Hispanic patients with RA undergoing THA or TKA at a high-volume specialty hospital, unlike Black or Hispanic patients with osteoarthritis (OA), there was no association with worse pain, function, or RA disease activity at the time of elective arthroplasty.

Nanoscale Characterization of Growth of Secondary Phases in Off-Stoichiometric CZTS Thin Films.

The presence of secondary phases is one of the main issues that hinder the growth of pure kesterite Cu2ZnSnS4 (CZTS) based thin films with suitable electronic and junction properties for efficient solar cell devices. In this work, CZTS thin films with varied Zn and Sn content have been prepared by RF-power controlled co-sputtering deposition using Cu, ZnS and SnS targets and a subsequent sulphurization step. Detailed TEM investigations show that the film shows a layered structure with the majority of the top layer being the kesterite phase. Depending on the initial thin film composition, either about ~1 µm Cu-rich and Zn-poor kesterite or stoichiometric CZTS is formed as top layer. X-ray diffraction, Raman spectroscopy and transmission electron microscopy reveal the presence of Cu2-xS, ZnS and SnO2 minor secondary phases in the form of nanoinclusions or nanoparticles or intermediate layers.

Optical properties and band alignments in ZnTe nanoparticles/MoS2 layer hetero-interface using SE and KPFM studies.

Integration of a layered two-dimensional (2D) material with a non-2D material provides a platform where one can modulate and achieve the properties desired for various next-generation electronic and opto-electronic applications. Here, we investigated ZnTe nanoparticles/MoS2 hetero-interfaces with the thickness of the MoS2 varying from few to multilayer. High-resolution transmission electron microscopy was used to observe the crystalline behaviour of the ZnTe nanoparticles, while the number of MoS2 layers was investigated using Raman measurements. Spectroscopic ellipsometry (SE) analysis based on the five-layer fitting model was used to analyse the optical behaviour of the heterojunction, where the excitonic features corresponding to the MoS2 layers and absorption features due to the ZnTe nanoparticles are observed. From the Kelvin probe force microscopy (KPFM) measurements, the surface potential (SP) of the ZnTe nanoparticles/MoS2 is found to be different in comparison with the SP of the ZnTe nanoparticles and MoS2, which is indicative of the charge transfer at the ZnTe nanoparticles/MoS2 hetero-interface. Various parameters obtained using SE and KPFM measurements were used to propose energy band alignments at the ZnTe nanoparticles/MoS2 hetero-interface. In addition, an interface photovoltage of 193 mV was obtained by carrying out KPFM measurements under illuminating condition.

A phase 3 randomized placebo-controlled trial of darbepoetin alfa in patients with anemia and lower-risk myelodysplastic syndromes.

The use of darbepoetin alfa to treat anemia in patients with lower-risk myelodysplastic syndromes (MDS) was evaluated in a phase 3 trial. Eligible patients had low/intermediate-1 risk MDS, hemoglobin ⩽10 g/dl, low transfusion burden and serum erythropoietin (EPO) ⩽500 mU/ml. Patients were randomized 2:1 to receive 24 weeks of subcutaneous darbepoetin alfa 500 µg or placebo every 3 weeks (Q3W), followed by 48 weeks of open-label darbepoetin alfa. A total of 147 patients were randomized, with median hemoglobin of 9.3 (Q1:8.8, Q3:9.7) g/dl and median baseline serum EPO of 69 (Q1:36, Q3:158) mU/ml. Transfusion incidence from weeks 5-24 was significantly lower with darbepoetin alfa versus placebo (36.1% (35/97) versus 59.2% (29/49), P=0.008) and erythroid response rates increased significantly with darbepoetin alfa (14.7% (11/75 evaluable) versus 0% (0/35 evaluable), P=0.016). In the 48-week open-label period, dose frequency increased from Q3W to Q2W in 81% (102/126) of patients; this was associated with a higher hematologic improvement-erythroid response rate (34.7% (34/98)). Safety results were consistent with a previous darbepoetin alfa phase 2 MDS trial. In conclusion, 24 weeks of darbepoetin alfa Q3W significantly reduced transfusions and increased rates of erythroid response with no new safety signals in lower-risk MDS (registered as EudraCT#2009-016522-14 and NCT#01362140).

Achieving independent control of core diameter and carbon shell thickness in Pd-C core-shell nanoparticles by gas phase synthesis.

Pd-C core-shell nanoparticles with independently controllable core size and shell thickness are grown by gas phase synthesis. First, the core size is selected by electrical mobility values of charged particles, and second, the shell thickness is controlled by the concentration of carbon precursor gas. The carbon shell grows by adsorption of carbon precursor gas molecules on the surface of nanoparticles, followed by sintering. The presence of a carbon shell on Pd nanoparticles is potentially important in hydrogen-related applications operating at high temperatures or in catalytic reactions in acidic/aqueous environments.

A Parametric Study on the Influence of Synthesis and Transfer Conditions on the Quality of Graphene.

In this paper, a systematic and comprehensive study has been carried out to observe the effect of synthesis and transfer conditions on the quality and uniformity of graphene deposition in an atmospheric pressure chemical vapour deposition set up. It was observed that the quality of graphene was highly affected by the synthesis conditions, such as, synthesis temperature, synthesis duration, methane and hydrogen flow rate ratio and total flow rate during deposition and cooling cycles. The quality of graphene was observed to be significantly improved upon increasing the synthesis temperature while increase in methane and hydrogen flow rates beyond a particular limit resulted into degradation in the quality of graphene. From the comparison of scanning electron microscopy images of graphene grown at different times, it was found that the nucleation and growth of graphene domains strongly depend on the growth time. The process of transfer of monolayer graphene was significantly improved by controlling the PMMA concentration using a modified three step technique. Raman spectroscopy and the high mobility (˜8153 cm2V−1s−1) of graphene after transferred onto a SiO2/Si substrate confirm the high quality of monolayer graphene obtained by the optimizations of synthesis and transfer conditions in this study.

A fast and effective approach for reversible wetting-dewetting transitions on ZnO nanowires.

Here, we demonstrate a facile approach for the preparation of ZnO nanowires (NWs) with tunable surface wettability that can be manipulated reversibly in a controlled manner from a superhydrophilic state to a superhydrophobic state. The as-synthesized ZnO NWs obtained by a chemical vapor deposition method are superhydrophilic with a contact angle (CA) value of ~0°. After H2 gas annealing at 300 °C for 90 minutes, ZnO NWs display superhydrophobic behavior with a roll-off angle less than 5°. However, O2 gas annealing converts these superhydrophobic ZnO NWs into a superhydrophilic state. For switching from superhydrophobic to superhydrophilic state and vice versa in cyclic manner, H2 and O2 gas annealing treatment was used, respectively. A model based on density functional theory indicates that the oxygen-related defects are responsible for CA switching. The water resistant properties of the ZnO NWs coating is found to be durable and can be applied to a variety of substrates including glass, metals, semiconductors, paper and even flexible polymers.

Exploring Nanoscale Electrical Properties of CuO-Graphene Based Hybrid Interfaced Memory Device by Conductive Atomic Force Microscopy.

The phenomenon of resistive switching is based on nanoscale changes in the electrical properties of the interface. In the present study, conductive atomic force microscope based nanoscale measurements of copper oxide (CuO-multilayer graphene (MLG) hybrid interface based devices have been carried out to understand changes in the electrical properties during resistive switching of the Ti-CuO/MLG-Cu memory cells having different dimensions fabricated on the same substrate using stencil lithography technique. The dependence of resistive switching characteristics in LRS and HRS and current level of the conductive filaments (CF) on the electrode area have been studied. As the device dimension is reduced, the filamentary contribution is enhanced in comparison to the background contribution, resulting in'an increase in the current density ratio between LRS and HRS. It is also observed that as the device dimension is decreased from 150 to 25 µm, the filament size decreases from 95 nm to 20 nm, respectively, which causes a decrease in the reset current and reset voltage. The results of the nanoscale CAFM measurements have shown a good correlation with the switching parameters obtained by the macroscale pad I-V measurements, thereby, suggesting the origin of resistive switching is due to the formation and rupture of an entity called filament, whose dimension is in nanorange. It is observed that changes in the electrical properties of the overall interface layer along with changes in the electrical conductivity of these filaments contribute towards resistive switching phenomenon. This study suggests that a significant reduction of reset current can be achieved by decreasing the memory device dimensions.

Visible-Light-Driven Photoelectrochemical and Photocatalytic Performance of NaNbO3 /Ag2 S Core-Shell Heterostructures.

Herein, we report the fabrication of visible-light-active NaNbO3 /Ag2 S staggered-gap core-shell semiconductor heterostructures with excellent photoelectrochemical activity toward water splitting, and the degradation of a model pollutant (methylene blue) was also monitored. The heterostructures show a pronounced photocurrent density of approximately 2.44 mA cm(-2) at 0.9 V versus Ag/AgCl in 0.5 m Na2 SO4 and exhibit a positive shift in onset potential by approximately 1.1 V. The high photoactivity is attributed to the efficient photoinduced interfacial charge transfer (IFCT). The core-shell design alleviates the challenges associated with the electron-hole paths across semiconductor junctions and at the electrolyte-semiconductor interface. These properties demonstrate that NaNbO3 /Ag2 S core-shell heterostructures show promising visible-light photoactivity and are also efficient, stable, and recyclable photocatalysts.

Synthesis and Characterization of Bi2Te3 Nanostructured Thin Films.

Thin films of Bi2Te3 were obtained using vacuum evaporation and inert gas evaporation techniques. To study the effect of nanocrystallite size on thermal and electrical properties, deposition temperature and gas pressure were varied and thin films of Bi2Te3 having different crystallite sizes ranging from 7-20 nm were obtained. X-ray Diffraction and scanning electron microscopic studies were carried out to determine phase, crystallite size, strain and surface morphology of nanocrystalline films. Effect of nanocrystallite size on electron transport and thermal properties of Bi2Te3 thin films was studied using Hall effect and Harman's four probe methods. Calculated ZT values were correlated with the carrier concentration, carrier mobility and electrical conductivity of Bi2Te3 thin films. This study shows that strain may influence the electron transport and thermoelectric properties of Bi2Te3 films along with nanocrystallite size.

Safety and effectiveness of sacroplasty: a large single-center experience.

BACKGROUND AND PURPOSE: Sacral insufficiency fractures are a common cause of severe low back pain and immobilization in patients with osteoporosis or cancer. Current practice guideline recommendations range from analgesia and physical therapy to resection with surgical fixation. We sought to assess the safety and effectiveness of sacroplasty, an emerging minimally invasive treatment. MATERIALS AND METHODS: We performed a retrospective review of institutional databases for percutaneous sacroplasty performed between January 2004 and September 2013. Demographic and procedural data and pre- and posttreatment Visual Analog Scale, Functional Mobility Scale, and Analgesic Scale scores were reviewed. Overall response was rated by using a 4-point scale (1, complete resolution of pain; 2, improvement of pain; 3, no change; 4, worsened pain) assessed at short-term follow-up. RESULTS: Fifty-three patients were included; most (83%) were female. Fracture etiology was cancer-related (55%), osteoporotic insufficiency (30%), and minor trauma (15%). No major complication or procedure-related morbidity occurred. There were statistically significant decreases in the Visual Analog Scale (P < .001), Functional Mobility Scale (P < .001), and Analgesic Scale scores (P < .01) in 27 patients with recorded data: pretreatment Visual Analog Scale (median [interquartile range], 9.0 [8.0-10.0]); Functional Mobility Scale, 3.0 (2.0-3.0); and Analgesic Scale scores, 3.0 (3.0-4.0) were reduced to 3.0 (0.0-5.8), 1.0 (0.25-2.8), and 3.0 (2.0-3.8) posttreatment. When we used the overall 4-point score at a mean of 27 days, 93% (n = 45) reported complete resolution or improvement in overall pain. CONCLUSIONS: In this single-center cohort, sacroplasty was a safe and effective procedure. There were significant short-term gains in pain relief, increased mobility, and decreased dependence on pain medication.

Transarterial onyx embolization of cranial dural arteriovenous fistulas: long-term follow-up.

BACKGROUND AND PURPOSE: Endovascular therapy with liquid embolic agents is a common treatment strategy for cranial dural arteriovenous fistulas. This study evaluated the long-term effectiveness of transarterial Onyx as the single embolic agent for curative embolization of noncavernous cranial dural arteriovenous fistulas. MATERIALS AND METHODS: We performed a retrospective review of 40 consecutive patients with 41 cranial dural arteriovenous fistulas treated between March 2006 and June 2012 by using transarterial Onyx embolization with intent to cure. The mean age was 57 years; one-third presented with intracranial hemorrhage. Most (85%) had cortical venous drainage. Once angiographic cure was achieved, long-term treatment effectiveness was assessed with DSA and clinical follow-up. RESULTS: Forty-nine embolization sessions were performed; 85% of cranial dural arteriovenous fistulas were treated in a single session. The immediate angiographic cure rate was 95%. The permanent neurologic complication rate was 2% (mild facial palsy). Thirty-five of the 38 patients with initial cure underwent short-term follow-up DSA (median, 4 months). The short-term recurrence rate was only 6% (2/35). All patients with occlusion at short-term DSA undergoing long-term DSA (median, 28 months) had durable occlusion. No patient with long-term clinical follow-up (total, 117 patient-years; median, 45 months) experienced hemorrhage. CONCLUSIONS: Transarterial embolization with Onyx as the single embolic agent results in durable long-term cure of noncavernous cranial dural arteriovenous fistulas. Recurrence rates are low on short-term follow-up, and all patients with angiographic occlusion on short-term DSA follow-up have experienced a durable long-term cure. Thus, angiographic cure should be defined at short-term follow-up angiography instead of at the end of the final embolization session. Finally, long-term DSA follow-up may not be necessary if occlusion is demonstrated on short-term angiographic follow-up.

In-flight gas phase growth of metal/multi layer graphene core shell nanoparticles with controllable sizes.

In this report, we present a general method for a continuous gas-phase synthesis of size-selected metal/multi layer graphene (MLG) core shell nanoparticles having a narrow size distribution of metal core and MLG shell for direct deposition onto any desired substrate kept under clean vacuum conditions. Evolution of MLG signature is clearly observed as the metal-carbon agglomerates get transformed to well defined metal/MLG core shell nanoparticles during their flight through the sintering zone. The growth takes place via an intermediate state of alloy nanoparticle (Pd-carbon) or composite nanoparticle (Cu-carbon), depending upon the carbon solubility in the metal and relative surface energy values. It has been also shown that metal/MLG nanoparticles can be converted to graphene shells. This study will have a large impact on how graphene or graphene based composite nanostructures can be grown and deposited in applications requiring controllable dimensions, varied substrate choice, large area and large scale depositions.

Study of charge separation and interface formation in a single nanorod CdS-Cu(x)S heterojunction solar cell using Kelvin probe force microscopy.

In the present investigation, Kelvin probe force microscopy (KPFM) is used to study the charge separation, shift in Fermi level position and interfacial depletion region formation in a single cadmium sulfide (CdS)-copper sulfide (CuxS) nanorod heterojunction fabricated using hydrothermal synthesis and a topotaxial conversion reaction. A detailed analysis of KPFM images in the dark shows work function (or Fermi energy) values of CdS and CuxS regions consistent with the energy band diagram of the CdS-CuxS junction. Under illumination, Fermi energy levels of both the CuxS and CdS shift away from the vacuum level by 0.2 and 0.4 eV, respectively, which is very different from the behaviour expected in the case of a bulk p-n junction. The existence of interfacial regions topographically placed between ITO-CdS and CdS-CuxS with intermediate work function values as well as the observed narrowing of the work function spread under illumination are important for understanding the fundamental process of charge separation and junction formation in semiconductor nanorod solar cells.

Antireflection properties of graphene layers on planar and textured silicon surfaces.

In this study, theoretical and experimental investigations have been carried out to explore the suitability of graphene layers as an antireflection coating. Microwave plasma enhanced chemical vapor deposition and chemically grown graphene layers deposited on polished and textured silicon surfaces show that graphene deposition results in a large decrease in reflectance in the wavelength range of 300-650 nm, especially in the case of polished silicon. A Si3N4/textured silicon reference antireflection coating and graphene deposited polished and textured silicon exhibit similar reflectance values, with the graphene/Si surface showing lower reflectance in the 300-400 nm range. Comparison of experimental results with the finite difference time domain calculations shows that the graphene along with a SiO2 surface layer results in a decrease in reflectance in the 300-650 nm range, with a reflectance value of <5% for the case of graphene deposited textured silicon surfaces. The monolayer and inert character along with the high transmittance of graphene make it an ideal surface layer. The results of the present study show its suitability as an antireflection coating in solar cell and UV detector applications.

CAFM investigations of filamentary conduction in Cu2O ReRAM devices fabricated using stencil lithography technique.

With the objective of understanding the role of size and current level of filamentary regions on the resistive switching parameters, detailed conductive atomic force microscope investigations of resistive memory cells having different dimensions have been carried out in this study. Cu-Cu(2)O-Ti memory cells having dimensions of 150, 50 and 25 µm have been fabricated on the same substrate using a stencil lithography technique. The dependence of resistive switching parameters on the device dimensions can be directly related to the average size, current level of the filaments and difference in these parameters between the low resistance state (LRS) and high resistance state (HRS). It is observed that the large increase in the ratio of current in the two states in cells having lower dimensions is mainly due to the smaller number of conducting regions in the HRS, indicating efficient switching from the LRS to the HRS at lower dimensions.