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Generation and manipulation of phonon polaritons are of paramount importance for understanding the interaction between an electromagnetic field and dielectric materials and furthering their application in mid-infrared optical communication. However, the formation of tunable one-dimensional phonon polaritons has been rarely realized in van der Waals layered structures. Here we report the discovery of curvature-induced phonon polaritons localized at the crease of folded hexagonal boron nitrides (

The main path of development credit funds in rural poverty alleviation in Y province is crucial. This paper studies the rural poverty alleviation work in extreme poverty areas in Yunnan and puts forward targeted and instructive policy suggestions for specific difficult areas. Research the relationship between credit resource allocation and rural poverty alleviation. The existing research is mainly based on the relationship between financial development and economic growth, income growth, income distribution, and, on the surface, the relationship between the scale of financial development and the efficiency of financial development and other indicators. The purpose is to put forward targeted measures and suggestions on the basis of theoretical research and model analysis to help the Yunnan banking industry support poverty alleviation. The results of the study show that there is a causal relationship between agriculture-related loans.

We characterize the effect of ferromagnetic nickel nanoparticles (size ∼6nm) on the magnetotransport properties of chemical-vapor-deposited (CVD) graphene. The nanoparticles were formed by thermal annealing of a thin Ni film evaporated on top of a graphene ribbon. The magnetoresistance was measured while sweeping the magnetic field at different temperatures, and compared against measurements performed on pristine graphene. Our results show that, in the presence of Ni nanoparticles, the usually observed zero-field peak of resistivity produced by weak localization is widely suppressed (by a factor of ∼3), most likely due to the reduction of the dephasing time as a consequence of the increase in magnetic scattering. On the other hand, the high-field magnetoresistance is amplified by the contribution of a large effective interaction field. The results are discussed in terms of a local exchange coupling, J∼6meV, between the graphene π electrons and the 3d magnetic moment of nickel. Interestingly, this magnetic coupling does not affect the intrinsic transport parameters of graphene, such as the mobility and transport scattering rate, which remain the same with and without Ni nanoparticles, indicating that the changes in the magnetotransport properties have a purely magnetic origin.

Pure copper (Cu) material, because of its high thermal conductivity, can be 3D printed to fabricate effective thermal management components. However, in the selective laser melting (SLM) process, due to copper’s high optical reflectivity, Cu-based parts need to be printed using high laser power. In this study, we demonstrated 3D printing with a re-melting strategy is able to fabricate high-density and low-surface-roughness pure copper parts using only a moderate laser (350 W) power. The effect of the re-scan to initial scan speed ratio on the printing quality resulting from the re-melting strategy is discussed. The re-melting strategy is likened to a localized annealing process that promotes the recrystallization of the newly formed copper microstructures on the re-scan path. Given a hatch spacing of 0.06 mm and a powder layer thickness of 0.05 mm, Cu samples with 93.8% density and low surface roughness (Sa~22.9 μm) were produced using an optimized scan speed of 200 mm/s and a re-scanning speed of 400 mm/s, with a laser power of 350 W. Our work provides an approach to optimize the laser power for printing pure copper 3D parts with high relative density (low porosity) and low surface roughness while ensuring the lifetime stability of the part. The re-melting strategies have broad implications in 3D printing and are particularly relevant for metals with high reflectivity, such as pure copper.

The physical properties of two-dimensional (2D) materials may drastically vary with their thickness profiles. Current thickness profiling methods for 2D material (e.g., atomic force microscopy and ellipsometry) are limited in measurement throughput and accuracy. Here we present a novel high-speed and high-precision thickness profiling method, termed Transmission-Matrix Quantitative Phase Profilometry (TM-QPP). In TM-QPP, picometer-level optical pathlength sensitivity is enabled by extending the photon shot-noise limit of a high sensitivity common-path interferometric microscopy technique, while accurate thickness determination is realized by developing a transmission-matrix model that accounts for multiple refractions and reflections of light at sample interfaces. Using TM-QPP, the exact thickness profiles of monolayer and few-layered 2D materials (e.g., MoS2, MoSe2 and WSe2) are mapped over a wide field of view within seconds in a contact-free manner. Notably, TM-QPP is also capable of spatially resolving the number of layers of few-layered 2D materials.

Thanks to rapid technological innovation over the last decade, a wide range of wearable devices have emerged, playing an inspiring role in healthcare, diagnostics, and sports monitoring. This review summarizes recent progress in the development and application of electrochemical (EC) sweat sensors and self-powered systems for wearable applications. Presented here are the most common types of EC sweat sensors, namely potentiometric ion-selective electrodes, amperometric enzymatic and non-enzymatic sensors, as well as differential pulse voltammetric sensors. The sensing principle and novel functional nanomaterials that are used to enhance the performance of wearable sweat sensors and their applications are summarized. The recent advancement of battery-free wearable devices is presented, including self-powered biofuel cells (BFC), energy harvesting from novel materials and its strategy, are also discussed. The challenges in, and opportunities for, the development of sweat sensor-based wearable systems moving forward are reviewed, with the aim of shedding some light on future directions.

Wearable sweat monitoring represents an attractive opportunity for personalized healthcare and for evaluating sports performance. One of the limitations with such monitoring, however, is water layer formation upon cycling of ion-selective sensors, leading to degraded sensitivity and long-term instability. Our report is the first to use chemical vapor deposition-grown, three-dimensional, graphene-based, gradient porous electrodes to minimize such water layer formation. The proposed design reduces the ion diffusion path within the polymeric ion-selective membrane and enhances the electroactive surface for highly sensitive, real-time detection of Na

Poly-l-lactic acid (PLLA) is a synthetic, biocompatible, biodegradable polymer with good piezoelectric properties. The prepared PLLA films were annealed in the oven at 140 °C for 0 h, 3 h, 12 h, and 24 h, respectively. The influences of temperature treatment time on the optoelectronic properties of the PLLA films and piezoelectric sensors based on them were investigated. The morphology and crystal structure of the PLLA films obtained under various post-processing conditions were examined by scanning electron microscopy, X-ray diffraction, Raman spectroscopy, and ATR-FTIR spectroscopy. The micromechanical equipment for tension-compression measurements was built in the laboratory for the tested piezoelectric sensors. The analysis of the structure shows that the increase in the crystallite size of the PLLA film influences the growth of the piezoelectric signal of the sensors based on them. The vibrational analysis of the PLLA films confirmed their crystal structure. The improvement in the structure and the stretching of the dipole C[double bond, length as m-dash]O for the film obtained after 3 h treatment increased the piezoelectric properties of the PLLA films. The analysis of Raman mapping added information that the area of the ordered phase of the PLLA films depends on the time of temperature treatment. The maximum value of the piezoelectric signal was 0.98 mV for sensors prepared on films annealed for 3 h at a load of 20 N. For films without temperature annealing at the same load, the maximum value was 0.45 mV. Thus, efficient converters of mechanical energy into electrical energy were obtained, which opens new innovative perspectives for the creation of flexible pressure sensors based on PLLA.

Several water-soluble variants of the human mu opioid receptor (wsMORs) have been designed and expressed, which enables the detection of opioids in the nM to pM range using biosensing platforms. The tools previously developed allowed us to investigate MOR and G-protein interactions in a lipid free system to demonstrate that the lipid bilayer might not be essential for the G-protein recognition and binding. In this study, we are able to investigate G-protein interactions with MOR by using graphene enabled technology, in a lipid free system, with a high sensitivity in a real time manner. A new wsMOR with the native C-terminus was designed, expressed and then immobilized on the surfaces of scalable graphene field effect transistor (GFET)-based biosensors, enabling the recording of wsMOR/G-protein interaction with an electronic readout. G-protein only interacts with the wsMOR in the presence of the native MOR C-terminus with a $\text{K}_{A}$ of 32.3± 11.1 pM. The electronic readout of such interaction is highly reproducible with little variance across 50 devices in one biosensor array. For devices with receptors that do not have the native C-terminus, no significant electronic response was observed in the presence of G-protein, indicating an absence of interaction. These findings reveal that lipid environment is not essential for the G-protein interaction with MOR, however, the C-terminus of MOR is essential for G-protein recognition and high affinity binding. A system to detect MOR-G protein interaction is developed. wsMOR-G2_Cter provides a novel tool to investigate the role of C terminus in the signaling pathway.

Introduction We aimed to assess our hypothesis that the expression changes of arginine vasopressin (AVP) in the magnocellular neurosecretory cells (MNCs) of hypothalamus and V2 receptor for AVP (RVP) in kidney may contribute to the pathogenesis of diabetic nephropathy (DN). Material and methods Twenty-five male Wistar rats were randomly assigned to the control group and the diabetes mellitus (DM) group. Periodic acid-Schiff (PAS) staining and electron microscopy were used for morphological studies. Immunohistochemical staining for glial fibrillary acidic protein (GFAP) is standard for visualization of reactive astrocytes in the hypothalamus. Hypothalamus was used for immunofluorescence of AVP. Kidney was used for immunohistochemical staining of RVP. Quantitative real-time reverse transcriptase polymerase chain reaction (qRT-PCR) was used for quantitative determinations of AVP mRNA in hypothalamus and RVP mRNA in kidney. Western blot was used to measure the protein expression of AVP in hypothalamus and RVP in kidney. Results Morphological studies showed abnormalities in kidney and hypothalamus in the DM group. The number of neurons and the gray value of astrocytes in hypothalamus in the DM group were markedly decreased. The expression level of AVP in hypothalamus and the expression level of RVP in kidney of DM rats were significantly increased. The positive correlations between the proteinuria and expression (mRNA and protein) of AVP, proteinuria and expression (mRNA and protein) of RVP, and the expression of AVP and RVP levels were found. Conclusions AVP was upregulated in the MNCs of hypothalamus and RVP was upregulated in kidney in streptozotocin-induced DM rats, indicating their potential roles in the development of DN.

Background: We report a case of serum myeloperoxidase (MPO)-anti-neutrophil cytoplasmic antibody (ANCA)-positive hypertrophic pachymeningitis with elevated serum immunoglobulin G (IgG)4.Case presentation: He was a 67-year-old man who appeared headache and hearing loss 7 years ago. He was treated with methylprednisolone and mycophenolate when he was diagnosed with hypertrophic pachymeningitis 2 years ago. He went to the hospital this time because of fatigue and appetite, the results of his blood tests indicated a progressive increase in creatinine and an increase in MPO and IgG4. His kidney biopsy revealed very few infiltrating IgG4-positive cells. Instead, fibrinoid necrosis of arterioles was observed. Considering the clinical process and these findings, the disease was considered more likely to be ANCA-associated hypertrophic pachymeningitis with elevated serum IgG4 level.Conclusions: Our case highlights the importance of the pathological examination and the medical history. Pathological examination and previous medical history play an essential role in the diagnosis of the disease. Only when the disease is correctly diagnosed can it be further treated effectively and get a better prognosis.Data Sources: Data were collected from the patient’s electronic medical records and the hospital laboratory medicine database.

We present experimental evidence of electronic and optical interlayer resonances in graphene van der Waals heterostructure interfaces. Using the spectroscopic mode of a low-energy electron microscope (LEEM), we characterized these interlayer resonant states up to 10 eV above the vacuum level. Compared with nontwisted, AB-stacked bilayer graphene (AB BLG), an $\ensuremath{\approx}0.2\text{ }\text{ }\AA{}$ increase was found in the interlayer spacing of 30\ifmmode^\circ\else\textdegree\fi{} twisted bilayer graphene (30\ifmmode^\circ\else\textdegree\fi{}-tBLG). In addition, we used Raman spectroscopy to probe the inelastic light-matter interactions. A unique type of Fano resonance was found around the D and G modes of the graphene lattice vibrations. This anomalous, robust Fano resonance is a direct result of quantum confinement and the interplay between discrete phonon states and the excitonic continuum.

Ultralow friction can be achieved with 2D materials, particularly graphene and MoS2. The nanotribological properties of these different 2D materials have been measured in previous atomic force microscope (AFM) experiments sequentially, precluding immediate and direct comparison of their frictional behavior. Here, friction is characterized at the nanoscale using AFM experiments with the same tip sliding over graphene, MoS2, and a graphene/MoS2 heterostructure in a single measurement, repeated hundreds of times, and also measured with a slowly varying normal force. The same material systems are simulated using molecular dynamics (MD) and analyzed using density functional theory (DFT) calculations. In both experiments and MD simulations, graphene consistently exhibits lower friction than the MoS2 monolayer and the heterostructure. In some cases, friction on the heterostructure is lower than that on the MoS2 monolayer. Quasi-static MD simulations and DFT calculations show that the origin of the friction contrast is the difference in energy barriers for a tip sliding across each of the three surfaces.

Insulator is one of the most widely used electrical equipment in power system, and its insulation state is related to the safe and stable operation of power system. In order to realize the intelligent diagnosis of the insulation state of the field running insulators, an intelligent diagnosis framework based on cloud computing and deep learning algorithm is designed; the browser / server development mode manages the UV images and videos of insulator discharge, and develops a set of image and video management data According to the database system, the database management system of UV imaging samples is constructed, which integrates the function of insulator visible light recognition and insulator discharge severity assessment based on UV image. The developed software is applied to the inspection of transmission lines and substations, and the application result is good.

We developed a high-yield synthesis of highly crystalline bilayer graphene (BLG) with two preferential stacking modes using a Ni-Cu gradient alloy growth substrate. Previously reported approaches for BLG growth include flat growth substrates of Cu or Ni-Cu uniform alloys and "copper pocket" structures. Use of flat substrates has the advantage of being scalable, but the growth mechanism is either "surface limited" (for Cu) or carbon precipitation (for uniform Ni-Cu), which results in multicrystalline BLG grains. For copper pockets, growth proceeds through a carbon back-diffusion mechanism, which leads to the formation of highly crystalline BLG, but scaling of the copper pocket structure is expected to be difficult. Here we demonstrate a Ni-Cu gradient alloy that combines the advantages of these earlier methods: the substrate is flat, so easy to scale, while growth proceeds by a carbon back-diffusion mechanism leading to high-yield growth of BLG with high crystallinity. The BLG layer stacking was almost exclusively Bernal or twisted with an angle of 30°, consistent with first-principles calculations we conducted. Furthermore, we demonstrated scalable production of transistor arrays based crystalline Bernal-stacked BLG with a band gap that was tunable at room temperature.

Visualization of the chemical structures of two-dimensional (2D) materials and their interfaces at the virtually atomic scale is an imperative step toward devising highly efficient ultrathin optoelectronic devices. Herein, we demonstrate a universal method featuring time-of-flight secondary ion mass spectrometry (ToF-SIMS), coupled with the structure simplicity of 2D materials, as a versatile tool to reveal the vertical atomic layers of various two-dimensional (2D) materials including graphene, hexagonal boron nitride (h-BN), and transition metal dichalcogenides (TMDs). We demonstrated that the vertical atomic layers of those 2D materials can be unveiled layer-by-layer using a strategy of ToF-SIMS three-dimensional (3D) analysis developed in this work. Moreover, we found that the extreme surface sensitivity and chemical specificity of ToF-SIMS also enables the examination of the lateral uniformity of 2D materials. During this process, we first removed interference of adsorbed organic contamination by anne...

The 2D geometry nature and low dielectric constant in transition-metal dichalcogenides lead to easily formed strongly bound excitons and trions. Here, we studied the photoluminescence of van der Waals heterostructures of monolayer MoS2 and graphene at room temperature and observed two photoluminescence peaks that are associated with trion emission. Further study of different heterostructure configurations confirms that these two peaks are intrinsic to MoS2 and originate from a bound state and Fermi level, respectively, of which both accept recoiled electrons from trion recombination. We demonstrate that the recoil effect allows us to electrically control the photon energy of trion emission by adjusting the gate voltage. In addition, significant thermal smearing at room temperature results in capture of recoil electrons by bound states, creating photoemission peak at low doping level whose photon energy is less sensitive to gate voltage tuning. This discovery reveals an unexpected role of bound states for ...

Heterostructures of transition metal dichalcogenides (TMDs) offer the attractive prospect of combining distinct physical properties derived from different TMD structures. Here, we report direct chemical vapor deposition of in-plane monolayer heterostructures based on 1H-MoS2 and 1T′-MoTe2. The large lattice mismatch between these materials led to intriguing phenomena at their interface. Atomic force microscopy indicated buckling in the 1H region. Tip-enhanced Raman spectroscopy showed mode structure consistent with Te substitution in the 1H region during 1T′-MoTe2 growth. This was confirmed by atomic resolution transmission electron microscopy, which also revealed an atomically stitched, dislocation-free 1H/1T′ interface. Theoretical modeling revealed that both the buckling and absence of interfacial misfit dislocations were explained by lateral gradients in Te substitution levels within the 1H region and elastic coupling between 1H and 1T′ domains. Phase field simulations predicted 1T′ morphologies with ...

Ultralow friction can be achieved with 2D materials, particularly graphene and MoS

Bilayer two-dimensional (2D) van der Waals (vdW) materials are attracting increasing attention due to their predicted high quality electronic and optical properties. Here we demonstrate dense, selective growth of WSe(2) bilayer flakes by chemical vapor deposition with the use of a 1:10 molar mixture of sodium cholate and sodium chloride as the growth promoter to control the local diffusion of W-containing species. A large fraction of the bilayer WSe(2) flakes showed a 0 (AB) and 60° (AA’) twist between the two layers, while moiré 15 and 30°-twist angles were also observed. Well-defined monolayer-bilayer junctions were formed in the as-grown bilayer WSe(2) flakes, and these interfaces exhibited p-n diode rectification and an ambipolar transport characteristic. This work provides an efficient method for the layer-controlled growth of 2D materials, in particular, 2D transition metal dichalcogenides and promotes their applications in next-generation electronic and optoelectronic devices.

The adsorption of chemical species on the surface of graphene alters the concentration of charge carries by either increasing or decreasing it depending on the nature of the adsorbed chemical species and inducing noticeable changes in the material's electronic properties. This remarkable feature enables graphene-based sensors to detect a wide range of biomolecules, chemicals, and gas/vapors. A lot of progress has been made in this field and technologies based on reduced graphene oxide flakes have been well reviewed. Graphene grown by chemical vapor deposition has proven to be the most prominent route to large-scale production of devices. However, until now, a comprehensive review on scalable, macro-sized, chemical vapor-deposited, graphene-based field-effect transistor sensors was missing. Here we review the present status, current challenges, and future prospects for the bio/chemical sensing applications of scalable, chemical vapor-deposited, graphene field-effect transistors. We explain and examine the fabrication techniques, sensing mechanisms, and various assay strategies. We also discuss the sensing performance of graphene based on quantum mechanics simulations and theoretical calculations.

Growth of transition metal dichalcogenide (TMD) monolayers is of interest due to their unique electrical and optical properties. Films in the 2H and 1T phases have been widely studied but monolayers of some 1T'-TMDs are predicted to be large-gap quantum spin Hall insulators, suitable for innovative transistor structures that can be switched via a topological phase transition rather than conventional carrier depletion [ Qian et al. Science 2014 , 346 , 1344 - 1347 ]. Here we detail a reproducible method for chemical vapor deposition of monolayer, single-crystal flakes of 1T'-MoTe2. Atomic force microscopy, Raman spectroscopy, X-ray photoelectron spectroscopy, and transmission electron microscopy confirm the composition and structure of MoTe2 flakes. Variable temperature magnetotransport shows weak antilocalization at low temperatures, an effect seen in topological insulators and evidence of strong spin-orbit coupling. Our approach provides a pathway to systematic investigation of monolayer, single-crystal 1T'-MoTe2 and implementation in next-generation nanoelectronic devices.

In the past few years, considerable progress has been made on the controlled synthesis of bilayer van der Waals (vdW) materials such as graphene and transition metal dichalcogenides (TMDs), which are of interest due to their attractive optical and electronic properties. A variety of methods have been developed to synthesize bilayer vdW materials. This review is devoted to recent advances in the properties and synthesis of bilayer graphene (BLG) and TMDs. We emphasize the intriguing properties of BLG and TMDs, depending on their composition, stacking configurations, and twisting angles. The large-scale chemical vapor deposition (CVD) growth of BLG and TMDs with large domain size, high quality, and strong interlayer coupling is highlighted. We then expand the discussion to the current understanding of the growth mechanisms of BLG by CVD and synthetic methods of bilayer TMDs. Finally, the crucial challenges of BLG synthesis and our perspective of the future of bilayer TMDs will be laid out for potential applications of vdW materials.

A simple technique of doping graphene by manipulating adsorbed impurity charges is presented. Using a field effect transistor configuration, controlled polarization of a ferroelectric polymer gate is used to compensate and neutralize charges of one type. The uncompensated charges of the opposite type then dope graphene. Both n- and p-type doping are possible by this method, which is non-destructive and reversible. We observe a change in n-type dopant concentration of 8 × 1012 cm−2 and a change in electron mobility of 650%. The electron and hole mobilities are inversely proportional to the impurity concentration, as predicted by theory. Selective doping of graphene can be achieved using this method by patterning gate electrodes at strategic locations and programming them independently. Such charge control without introducing hard junctions, therefore, permits seamless integration of multiple devices on a continuous graphene film.A simple technique of doping graphene by manipulating adsorbed impurity charges is presented. Using a field effect transistor configuration, controlled polarization of a ferroelectric polymer gate is used to compensate and neutralize charges of one type. The uncompensated charges of the opposite type then dope graphene. Both n- and p-type doping are possible by this method, which is non-destructive and reversible. We observe a change in n-type dopant concentration of 8 × 1012 cm−2 and a change in electron mobility of 650%. The electron and hole mobilities are inversely proportional to the impurity concentration, as predicted by theory. Selective doping of graphene can be achieved using this method by patterning gate electrodes at strategic locations and programming them independently. Such charge control without introducing hard junctions, therefore, permits seamless integration of multiple devices on a continuous graphene film.

Lyme disease is an infectious disease caused by the Borrelia burgdorferi bacterium. Early diagnosis of Lyme disease could prevent patients from developing serious side effects such as chronic arthritis and permanent neurological disorders. Lyme disease diagnosis is currently held back by a lack of reliable tools that are sufficiently sensitive and specific to allow early stage detection. Here, we demonstrate all electronic nano-biosensors for multiplexed detection of antigens of B. burgdorferi at concentrations as low as 2 pg ml−1. The sensors are based on graphene field-effect transistors (GFETs) coupled with genetically engineered antibody fragments. Single-chain variable fragment (scFv) antibodies are used to obtain a closer proximity of the target-binding event to the graphene sensor surface and for higher immobilization density. When compared to GFET nano-biosensors that use the parental immunoglobulin G (IgG) antibodies, scFv GFET nano-biosensors achieve approximately a 4000 × improvement to the limit of detection. We also demonstrate multiplexed detection of B. burgdorferi antigens through site-specific immobilization of scFvs on GFET arrays, which can potentially reduce the false-positive diagnosis ratio of Lyme disease. This work offers a pathway towards point-of-care detection of Lyme disease at an early stage.

Graphene, as well as other two-dimensional materials, is a promising candidate for use in bioimaging, therapeutic drug delivery, and bio-sensing applications. Here, we developed a protocol to functionalize graphene with recombinant proteins using genetically encoded SpyTag-SpyCatcher chemistry. SpyTag forms a covalent isopeptide bond with its genetically encoded partner SpyCatcher through spontaneous amidation under physiological conditions. The functionalization protocol developed is based on the use of short proteins as a linker, where two graphene-binding-peptides (GBPs) are attached to both ends of SpyTag (referred to as GStG), followed by the covalent conjugation with SpyCatcher-fusion proteins. The proposed method enables the decoration of crystalline graphene with various proteins, such as fluorescent proteins and affibody molecules that bind to cancerous cells. This scheme, which takes advantage of the cleanness of single-crystal graphene and the robustness of SpyTag-SpyCatcher chemistry, provides a versatile platform on which to study the biomolecule-surface and cell-substrate interactions and, indeed, may lead to a new way of designing biomedical devices. The interaction between peptides and graphene was clearly shown using molecular dynamics simulation and proven using specially designed experiments.

Diabetic nephropathy (DN) is by far the most common cause of end-stage renal disease (ESRD) in industrial countries, accounting for ~45% of all new ESRD cases in the United States. Grape seed proanthocyanidin extracts (GSPE) are powerful antioxidants, with an antioxidant ability 50-fold greater than that of vitamin E and 20-fold greater than that of vitamin C. The present study investigated whether GSPE can protect against streptozotocin (STZ)-induced DN and aimed to elucidate a possible mechanism. Male Sprague Dawley rats were randomly divided into three groups: Control group (N), diabetes mellitus group (DM) injected with 40 mg/kg STZ, and the GSPE treatment group (intragastric administration of 250 mg/kg/day GSPE for 16 weeks after diabetes was induced in the rats). Blood and kidney samples were collected after treatment. The renal pathological changes were determined with periodic acid-Schiff (PAS) staining, while the protein expression levels of glucose-regulated protein 78 (GRP78), phosphorylated-extracellular signal-regulated kinase (p-ERK) and Caspase-12 were determined by western blotting and immunohistochemical staining. Apoptosis was determined with a terminal deoxynucleotidyl transferase dUTP nick-end labeling (TUNEL) assay. Compared with the DM group, the GSPE group had no significant changes in the blood urea nitrogen (BUN) level and serum creatinine (Scr) level, but showed a significant decline in the renal index (RI) level and 24-h urinary albumin level (P

Large-area growth of monolayer films of the transition metal dichalcogenides is of the utmost importance in this rapidly advancing research area. The mechanical exfoliation method offers high quality monolayer material but it is a problematic approach when applied to materials that are not air stable. One important example is 1T’-WTe2, which in multilayer form is reported to possess a large non saturating magnetoresistance, pressure induced superconductivity, and a weak antilocalization effect, but electrical data for the monolayer is yet to be reported due to its rapid degradation in air. Here we report a reliable and reproducible large-area growth process for obtaining many monolayer 1T’-WTe2 flakes. We confirmed the composition and structure of monolayer 1T’-WTe2 flakes using x-ray photoelectron spectroscopy, energy-dispersive x-ray spectroscopy, atomic force microscopy, Raman spectroscopy and aberration corrected transmission electron microscopy. We studied the time dependent degradation of monolayer 1T’-WTe2 under ambient conditions, and we used first-principles calculations to identify reaction with oxygen as the degradation mechanism. Finally we investigated the electrical properties of monolayer 1T’-WTe2 and found metallic conduction at low temperature along with a weak antilocalization effect that is evidence for strong spin–orbit coupling.

We present a novel method for fabricating a high-density carbon nanotube microelectrode array (MEA) chip. Vertically aligned carbon nanotubes (VACNTs) were synthesized by microwave plasma-enhanced chemical vapor deposition and thermal chemical vapor deposition. The device was characterized using electrochemical experiments such as cyclic voltammetry, impedance spectroscopy and potential transient measurements. Through-silicon vias (TSVs) were fabricated and partially filled with polycrystalline silicon to allow electrical connection from the high-density electrodes to a stimulator microchip. In response to the demand for higher resolution implants, we have developed a unique process to obtain a high-density electrode array by making the microelectrodes smaller in size and designing new ways of routing the electrodes to current sources. Keywords: Microelectrode array, Neural implant, Carbon nanotubes, Through-silicon via interconnects, Microfabrication

Atomic diffusion-induced catalyst evolution affects the iron catalyst lifetime and the collective termination of VACNT growth on a metal substrate. We demonstrated that controlled catalyst diffusion in the pretreatment stage is capable of extending the iron catalyst lifetime on an aluminum thin-film substrate to allow enhanced vertically aligned carbon nanotube (VACNT) growth by a conventional low-pressure thermal chemical vapor deposition. In adopting a fast-heating pretreatment to control the catalyst loss from diffusion, catalyst lifetime was extended, leading to the VACNT growth with heights up to 65% taller than those without the diffusion control strategy. Atomic diffusion of iron catalyst along the grain boundaries of aluminum thin films was found to play a critical role in the catalyst loss mechanism. This work provides the basic understanding of catalyst diffusion control to facilitate the growth of VACNT arrays on metallic substrates for various applications such as through silicon via interconn...

Advances in techniques for monitoring pH in complex fluids could have significant impact on analytical and biomedical applications ranging from water quality assessment to in vivo diagnostics. We developed flexible graphene microelectrodes (GEs) for rapid (< 5 seconds), very low power (femtowatt) detection of the pH of complex biofluids. The method is based on real-time measurement of Faradaic charge transfer between the GE and a solution at zero electrical bias. For an idealized sample of phosphate buffer solution (PBS), the Faradaic current varied monotonically and systematically with the pH with resolution of ~0.2 pH unit. The current-pH dependence was well described by a hybrid analytical-computational model where the electric double layer derives from an intrinsic, pH-independent (positive) charge associated with the graphene-water interface and ionizable (negative) charged groups described by the Langmuir-Freundlich adsorption isotherm. We also tested the GEs in more complex bio-solutions. In the case of a ferritin solution, the relative Faradaic current, defined as the difference between the measured current response and a baseline response due to PBS, showed a strong signal associated with the disassembly of the ferritin and the release of ferric ions at pH ~ 2.0. For samples of human serum, the Faradaic current showed a reproducible rapid (

Cisplatin (CP) is used as an antineoplastic drug in the clinic, but its nephrotoxicity limits its use. Grape seed proanthocyanidin extract (GSPE) is a powerful antioxidant. In this study, we investigated whether GSPE can prevent CP-induced nephrotoxicity and explored the underlying mechanism. Male C57/BL6 mice were randomly divided into four groups: control group (N), CP group (C), receiving an intraperitoneal (ip) injection of 20 mg/kg CP, GSPE group (G), receiving an intragastric (ig) dose of 500 mg/kg GSPE, and CP+GSPE group (C+G), where ig administration of GSPE was performed 30 min prior to ip injection of CP, followed by an additional ig administration of GSPE 72 h later. Blood and kidney samples were collected 120 h after treatment. The pathological changes in the kidney were examined by periodic acid-Schiff (PAS) staining, while the protein levels of glucose-regulated protein 78 (GRP78), phosphorylated-extracellular signal-regulated kinase (p-ERK) and caspase-12 were examined by western blotting and immunohistochemical staining. Apoptosis was examined by a terminal deoxynucleotidyl transferase dUTP nick-end labeling (TUNEL) assay. Compared to the CP group, the CP+GSPE group had a significant decrease in the level of blood urea nitrogen (BUN), serum creatinine (Scr) and reduced renal index (RI) (P

We have uncovered some unusual thermal interface properties of a three-dimensional, flexible and interconnected graphene foam (GF). The thermal interfacial resistance of GF at Si–Al interface is as low as 0.04 cm2K W−1, which is one order of magnitude lower than conventional thermal grease and thermal paste-based thermal interfacial material (TIM). The thermal contact resistance was found to dominate the overall interfacial resistance of GF-based TIM, in as much as the bulk thermal conductivity of GF is rather high. The contact pressure-dependent thermal interfacial resistance of GF exhibits an asymptotic behavior, which converges into a plateau value at an ultralow contact pressure (∼0.1 MPa). Significantly, the GF-based TIM has shown a superior performance to vertically aligned carbon nanotubes currently held as the gold standard (at least ∼75% improvement in thermal interfacial resistance at Si–Al interface), thus providing a strong candidate for the next generation of high-performance carbon-based TIM.