Observation of Coexisting Weak Localization and Superconducting Fluctuations in Strained Sn1-xInxTe Thin Films.

Topological superconductors have attracted tremendous excitement as they are predicted to host Majorana zero modes that can be utilized for topological quantum computing. Candidate topological superconductor Sn1-xInxTe thin films (0 < x < 0.3) grown by molecular beam epitaxy and strained in the (111) plane are shown to host quantum interference effects in the conductivity coexisting with superconducting fluctuations above the critical temperature Tc. An analysis of the normal state magnetoresistance reveals these effects. A crossover from weak antilocalization to localization is consistently observed in superconducting samples, indicating that superconductivity originates dominantly from charge carriers occupying trivial states that may be strongly spin-orbit split. A large enhancement of the conductivity is observed above Tc, indicating the presence of superconducting fluctuations. Our results motivate a re-examination of the debated pairing symmetry of this material when subjected to quantum confinement and lattice strain.

Nanoscale Metastable ε-Fe3N Ferromagnetic Materials by Self-Sustained Reactions.

A single-step method for the preparation of metastable ε-Fe3N nanoparticles by combustion of reactive gels containing iron nitrate (Fe(NO3)3) and hexamethylenetetramine (C6H12N4) in an inert atmosphere is reported. The results of Fourier transform infrared spectroscopy (FTIR) and thermal analysis coupled with dynamic mass spectrometry revealed that the exothermic decomposition of a coordination complex formed between Fe(NO3)3 and HMTA is responsible for the formation of ε-Fe3N nanoscale particles with sizes of 5-15 nm. The magnetic properties between 5 and 350 K are characterized using a superconducting quantum interference device (SQUID) magnetometer, revealing a ferromagnetic behavior with a low-temperature magnetic moment of 1.09 µB/Fe, high room temperature saturation magnetization (∼80 emu/g), and low remanent magnetization (∼15 emu/g). The obtained value for the Curie temperature of ∼522 K is close to that (∼575 K) for bulk ε-Fe3N reported in the literature.

Silica nanoparticle remodeling under mild conditions: versatile one step conversion of mesoporous to hollow nanoparticles with simultaneous payload loading.

A binary mixture of mesoporous silica nanoparticles plus organic polyammonium additive (dye or drug) is cleanly converted upon mild heating into hollow nanoparticles. The remodeled nanoparticle shell is an organized nanoscale assembly of globular additive/silica subunits and cancer cell assays show that a loaded drug additive is bioavailable.

Porphyridium purpureum microalga physiological and ultrastructural changes under copper intoxication.

The present work assessed the effect of copper (Cu) on cell dynamics and structure of the microalga Porphyridium purpureum (Rhodophyta, Bangiophycidae). Ultrastructure of the microalga was investigated and fluorescence of chlorophyll a and phycoerythrin, and content of reactive oxygen species (ROS) were estimated by flow cytometry. The number of cells did not show statistically significant differences at concentrations of 50 and 100 µg/L of Cu compared to the control, whereas 150 µg/L of Cu inhibited population growth. The fluorescence of chlorophyll a increased following exposure to Cu 100 µg/L and fluorescence of phycoerythrin enhanced by Cu 150 µg/L. There was no alteration in the above indicators at other concentrations. The content of ROS increased with increasing Cu concentration in a dose-dependent manner. The population size structure was also changed by Cu as the number of cells sized 4-6 µm was increased in the presence of Cu, especially with Cu 150 µg/L. Changes in the topography of thylakoids grew larger with Cu concentration.

Layered transition metal dichalcogenides: promising near-lattice-matched substrates for GaN growth.

Most III-nitride semiconductors are grown on non-lattice-matched substrates like sapphire or silicon due to the extreme difficulty of obtaining a native GaN substrate. We show that several layered transition-metal dichalcogenides are closely lattice-matched to GaN and report the growth of GaN on a range of such layered materials. We report detailed studies of the growth of GaN on mechanically-exfoliated flakes WS2 and MoS2 by metalorganic vapour phase epitaxy. Structural and optical characterization show that strain-free, single-crystal islands of GaN are obtained on the underlying chalcogenide flakes. We obtain strong near-band-edge emission from these layers, and analyse their temperature-dependent photoluminescence properties. We also report a proof-of-concept demonstration of large-area growth of GaN on CVD MoS2. Our results show that the transition-metal dichalcogenides can serve as novel near-lattice-matched substrates for nitride growth.

Urinary proteomic analysis of chronic allograft nephropathy.

The pathogenesis of progressive renal allograft injury, which is termed chronic allograft nephropathy (CAN), remains obscure and is currently defined by histology. Prospective protocol-biopsy trials have demonstrated that clinical and standard laboratory tests are insufficiently sensitive indicators of the development and progression of CAN. The study aim was to determine if CAN could be characterized by urinary proteomic data and identify the proteins associated with disease. The urinary proteome of 75 renal transplant recipients and 20 healthy volunteers was analyzed using surface enhanced laser desorption and ionization MS. Patients could be classified into subgroups with normal histology and Banff CAN grades 2-3 with a sensitivity of 86% and a specificity of 92% by applying the classification algorithm Adaboost to urinary proteomic data. Several urinary proteins associated with advanced CAN were identified including α1-microglobulin, ß2-microglobulin, prealbumin, and endorepellin, the antiangiogenic C-terminal fragment of perlecan. Increased urinary endorepellin was confirmed by ELISA and increased tissue expression of the endorepellin/perlecan ratio by immunofluoresence analysis of renal biopsies. In conclusion, analysis of urinary proteomic data has further characterized the more severe CAN grades and identified urinary endorepellin, as a potential biomarker of advanced CAN.

Cyclic arginine-glycine-aspartic acid peptide inhibits macrophage infiltration of the kidney and carotid artery lesions in apo-E-deficient mice.

Interactions of leukocytes with the vascular endothelium culminating in their diapedesis represent not only a crucial event in immune surveillance and defense but are also critically involved in the pathogenesis of many inflammatory diseases, including atherosclerosis. Our previous in vitro studies using atomic force microscopy measurement of monocyte-endothelial cell interaction have demonstrated that a cyclic arginine-glycine-aspartic acid peptide (cRGD) inhibited their adhesion through very late antigen (alpha4beta1-integrin; VLA4)-vascular cell adhesion molecule-1 by 60% with the IC50 = 100 nM. To elucidate the potential efficacy of this peptide in vivo in preventing atherogenesis, experiments were performed in apolipoprotein E (ApoE)-deficient (-/-) mice fed a Western diet and receiving chronic treatment with cRGD peptide for 2-4 wk. In addition, some animals were subjected to a temporary carotid artery ligation while receiving the above treatment. Formation of fatty streaks and infiltration of the vascular wall with macrophages were not affected by cRGD treatment. Infiltration of the carotid artery postligation was significantly reduced in the cRGD-treated animals, as was the lipid accumulation. Furthermore, cRGD-treated ApoE-/- mice exhibited significantly lesser macrophage infiltration and lipid accumulation in the kidneys, the site of the highest expression of VLA4. These data demonstrated that cRGD peptide is a potent inhibitor of monocyte/macrophage infiltration of the injured macrovasculature and of the renal microvasculature, where it results in the attenuation of lipid accumulation. Formation of fatty streaks in the aortic root was not inhibitable by this treatment.

Urinary proteome of steroid-sensitive and steroid-resistant idiopathic nephrotic syndrome of childhood.

The response to steroid therapy is used to characterize the idiopathic nephrotic syndrome (INS) of childhood as either steroid-sensitive (SSNS) or steroid-resistant (SRNS), a classification with a better prognostic capability than renal biopsy. The majority (approximately 80%) of INS is due to minimal change disease but the percentage of focal and segmental glomerulosclerosis is increasing. We applied a new technological platform to examine the urine proteome to determine if different urinary protein excretion profiles could differentiate patients with SSNS from those with SRNS. Twenty-five patients with INS and 17 control patients were studied. Mid-stream urines were analyzed using surface enhanced laser desorption and ionization mass spectrometry(SELDI-MS). Data were analyzed using multiple bioinformatic techniques. Patient classification was performed using Biomarker Pattern Software and a generalized form of Adaboost and predictive models were generated using a supervised algorithm with cross-validation. Urinary proteomic data distinguished INS patients from control patients, irrespective of steroid response, with a sensitivity of 92.3%, specificity of 93.7%, positive predictive value of 96% and a negative predictive value of 88.2%. Classification of patients as SSNS or SRNS was 100%. A protein of mass 4,144 daltons was identified as the single most important classifier in distinguishing SSNS from SRNS. SELDI-MS combined with bioinformatics can identify different proteomic patterns in INS. Characterization of the proteins of interest identified by this proteomic approach with prospective clinical validation may yield a valuable clinical tool for the non-invasive prediction of treatment response and prognosis.

Bioinformatic analysis of the urine proteome of acute allograft rejection.

The urinary proteome in health and disease attracts increasing attention because of the potential diagnostic and pathophysiologic biomarker information carried by specific excreted proteins or their constellations. This cross-sectional study aimed to analyze the urinary proteome in patients with biopsy-proven acute rejection (n = 23) compared with transplant recipients with stable graft function (n = 22) and healthy volunteers (n = 20) and to correlate this with clinical, morphologic, and laboratory data. Urine samples were preadsorbed on four different protein chip surfaces, and the protein composition was analyzed using a surface-enhanced laser desorption/ionization time-of-flight mass spectrometer platform. The data were analyzed using two independent approaches to sample classification. Patients who experienced acute rejection could be distinguished from stable patients with a sensitivity of 90.5 to 91.3% and a specificity of 77.2 to 83.3%, depending on the classifier used. Protein masses that were important in constructing the classification algorithms included those of mass 2003.0, 2802.6, 4756.3, 5872.4, 6990.6, 19,018.8, and 25,665.7 Da. Normal urine was distinguished from transplant urine using a protein marker of mass 78,531.2 Da with both a sensitivity and a specificity of 100%. In conclusion, (1) urine proteome in transplant recipients with stable graft function was significantly different from healthy control subjects, and (2) acute rejections were characterized by a constellation of excreted proteins. Analysis of the urinary proteome may expedite the noninvasive prediction of acute graft rejection, thus importantly assisting in establishing the diagnosis.