Search

Light-element-based fluorescent materials, colloidal graphene quantum dots, and carbon dots (CDs) have sparked an immense amount of scientific interest in the past decade. However, a significant challenge in practical applications has emerged concerning the development of solid-state fluorescence (SSF) materials. This study addresses this knowledge gap by exploring the unexplored photonic facets of C-based solid-state microphotonic emitters. The proposed synthesis approach focuses on carbonized polymer microspheres (CPMs) instead of conventional nanodots. These microspheres exhibit remarkable SSF spanning the entire visible spectrum from blue to red. The highly spherical shape of CPMs imparts built-in photonic properties in addition to its intrinsic CD-based attributes. Leveraging their excitation-dependent photoluminescence property, these microspheres exhibit amplified spontaneous emission, assisted by the whispering gallery mode resonance across the visible spectral region. Remarkably, unlike conventional semiconductor quantum dots or dye-doped microresonators, this single microstructure showcases adaptable resonant emission without structural/chemical modifications. This distinctive attribute enables a plethora of applications, including microcavity-assisted energy transfer for white light emission, highly sensitive chemical sensing, and secure encrypted anticounterfeiting measures. This interdisciplinary approach, integrating photonics and chemistry, provides a robust solution for light-element-based SSF with inherent photonic functionality and wide-ranging applications.

High entropy alloys (HEAs), a novel class of material, have been explored in terms of their excellent mechanical properties. Seawater electrolysis is a step towards sustainable production of carbon-neutral fuels such as H 2 , O 2 , and industrially demanding Cl 2 . Herein, we report a practically viable FeCoNiMnCr HEA nanoparticles system grafted on a conductive carbon matrix for promising seawater electrolysis. The comprehensive kinetics analysis of the hydrogen evolution reaction (HER), oxygen evolution reaction (OER), and chlorine evolution reaction (CER) confirms the effectiveness of our system. As an electrocatalyst, HEAs grafted on carbon black show trifunctionality with promising kinetics, selectivity and enduring performance, towards seawater splitting. We optimize high entropy alloy decorated/grafted carbon black (HEACB) catalysts, studying their synthesis temperature to scrutinize the effect of alloy formation variation on the catalysis efficacy. During the catalysis, selectivity between two mutually competing reactions, CER and OER, in the electrochemical catalysis of seawater is controlled by the reaction media pH. We employ Mott-Schottky measurements to probe the band structure of the intrinsically induced metal-semiconductor junction in the HEACB catalyst, where the carrier density and flat band potential are optimized. The HEACB sample provides promising results towards overall seawater electrolysis with a net half-cell potential of about 1.65 V with good stability, which strongly implies its broad practical applicability.

The potential presence of N-nitrosamines in medicinal products has become a matter of concern for health authorities and pharmaceutical companies. However, very little information is available in published literature on N-nitrosamine formation within pharmaceutical drug products. In response, experiments were undertaken to test if secondary and tertiary amines present in solid drug products could undergo nitrosation due to the presence of nitrite in the excipients used in the manufacture of the drug product. This work focused on solid dosage forms exploring several model amines of varying chemical structure, solubility and pKa which were formulated using common excipients with and without added nitrite. Monitoring the formation of the N-nitrosamines after processing and upon stressed stability conditions showed that N-nitrosamine formation can occur in solid drug product formulations. The results show that the rate and extent of N-nitrosamine formation depend upon the solubility of the amine, level of nitrite, expected local acidity in water layers within the drug product and mode of processing. Our findings agree with the rank order of dosage form risk from the published EFPIA workflows for quality risk management of N-nitrosamine risks in medicines (EFPIA, 2022): amorphous > wet granulation > direct compression > dry blends. In all cases the level of N-nitrosamine formation in solid dosage forms plateaued at a level that was significantly lower than the maximum theoretical yield based on the level of nitrite present. Trace secondary amine impurities were shown to be a significantly lower risk relative to cases containing a secondary amine present at drug substance levels. A comparison of secondary and simple tertiary alkylamine reactivity showed the tertiary amine to be significantly less reactive with nitrite., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023. Published by Elsevier Inc.)

Cathepsin K (Cat K) is a cysteine protease involved in bone remodeling. In addition to its role in bone biology, Cat K is upregulated in osteoclasts, chondrocytes and synoviocytes in osteoarthritic (OA) disease states making it a potential therapeutic target for disease-modifying OA. Starting from a prior preclinical compound, MK-1256, lead optimization efforts were carried out in the search for potent Cat K inhibitors with improved selectivity profiles with an emphasis on cathepsin F. Herein, we report the SAR studies which led to the discovery of the highly selective oxazole compound 23, which was subsequently shown to inhibit cathepsin K in vivo as measured by reduced levels of urinary C-telopeptide of collagen type I in dog., (Copyright © 2022 Elsevier Ltd. All rights reserved.)

We report a user-friendly methodology for the successful designing of targeted single-phased face-centered cubic (fcc) FeCoNiMnCr high-entropy alloy (HEA) nanoparticle-grafted N-doped carbon nanotubes (CNTs). The nanostructure assimilates the advantages of N-doped carbon and HEA nanoparticles as a core for the efficient promotion of electrochemical oxygen reduction reaction (ORR). It emulates the commercial Pt-C electrocatalyst for ORR and shows promise for better performance in the Ohmic polarization region of fuel cells. In addition, it ensures superior efficacy over those of numerous recently reported transition metal-based traditional alloy composites for ORR. The presented methodology has the potential to pave the way for the effective designing of a variety of targeted HEA systems with ease, which is necessary to widen the domain of HEA for numerous applications.

Though several Pt-free hydrogen evolution reaction (HER) catalysts have been reported, their employment for industry is challenging. Here, a facile pyrolysis method to obtain phase-pure CrP nanoparticles supported on N, P dual-doped carbon (CrP/NPC) is reported to be tuned toward industrial HER. Interestingly, CrP/NPC exhibits excellent HER activity that requires an overpotential of 34 mV to attain a current density of 10 mA cm -2 , which is only 1 mV positive to commercial Pt/C and a potential of 55 mV to achieve a current density of 200 mA cm -2 which is better than Pt/C. In addition, the long-term durability of CrP/NPC is far superior to Pt/C due to the strong interaction between CrP and C support, restricting any agglomeration or leaching. Density functional theory (DFT) calculations suggest that electronic modulation at the interface (CrP/NPC) optimizes the hydrogen adsorption energy. The Cr-Cr bridge site with required density of states near the Fermi level is found to be the active site. Overall, this report provides a practical scheme to synthesize rarely investigated CrP based materials along with a computational mechanistic guideline for electrocatalysis that can be utilized to explore other phosphides for various applications., (© 2022 Wiley-VCH GmbH.)

Here, we report on a universal carbothermal reduction strategy for the synthesis of well-dispersed WS 2 nanoparticles (∼1.7 nm) supported on a N-doped carbon (N x C) nanostructure and the electrocatalytic activity toward oxygen reduction reaction (ORR). Bulk WS 2 powder (2 μm) is the source for WS 2 nanoparticles, and dicyandiamide is the source for N x C and carbothermal reduction. Interestingly, WS 2 /N x C serves the purpose of innovative and robust active sites for ORR through an efficient four-electron transfer process with excellent durability. Remarkably, WS 2 /N x C suppresses the peroxide generation due to the dominating inner-sphere electron transfer mechanism where the direct adsorption of the desolvated O 2 molecule on the electroactive centers takes place. The mass activity (at 0.4 and 0.85 V vs RHE) of WS 2 /N x C outperforms the previously reported transition metal based electrocatalysts. The study further establishes a correlation between the work function and the ORR activity. We have also exploited WS 2 /N x C for electrochemical oxygen sensing, and there exists a direct correlation between oxygen sensing and ORR as both depend on the oxygen adsorption ability. Finally, the carbothermal reduction strategy has been extended for the synthesis of other TMDs/N x C such as MoS 2 /N x C, MoSe 2 /N x C, and WSe 2 /N x C.

Nitrosamines, in the absence of toxicological data, are regarded as potential mutagens and need to be controlled at nanogram levels in drug products. Recent high profile product withdrawals have increased regulatory scrutiny of nitrosamine formation assessments for marketed products and for new drug applications. Formation of nitrosamine in drug product is possible when nitrite and vulnerable amines are present. Nitrite is often present as an impurity in excipients at ppm levels, whereas vulnerable amines, if present, stem mainly from the drug substance or its major impurities. In the event a drug product were to contain a major source of vulnerable amines (such as a moiety in the drug substance), it would be desirable to have an inhibitor which could be added to the formulation to minimize nitrosamine formation.  This work demonstrates, for the first time, that the inhibition of nitrosamine formation in oral solid dosage forms is indeed feasible with suitable inhibitors. Five inhibitors investigated (ascorbic acid, sodium ascorbate, α-tocopherol, caffeic acid, and ferulic acid) showed >80% inhibition when spiked at ∼1 wt% level. This work has also shown the potential use of amino acids (glycine, lysine, histidine) as inhibitors of nitrosamine formation in solution., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2021 American Pharmacists Association. Published by Elsevier Inc. All rights reserved.)

It is challenging to realize a visible-blind infrared photodetector as the materials that absorb infrared light also absorb visible light. Here, we report the synthesis of IrP 2 nanoparticle-embedded few-layer graphene by one-step solid-state pyrolysis and its application in visible-blind infrared sensing. A linear photodetector device was fabricated by drop casting IrP 2 nanoparticle-embedded few-layer graphene onto a flexible PET substrate with two gold electrodes separated by ∼16 μm. The photoconductive gain was found to be as high as ∼145% with response and decay times of ∼0.4 and ∼2.8 s, respectively, under 1550 nm irradiation of 800 mW cm -2 . The room-temperature responsivity was ∼1.81 A W -1 at 80 mW cm -2 and ∼0.54 A W -1 at a high incident power of ∼2200 mW cm -2 under a bias of 1 V. Interestingly, the device showed response even in the long-wavelength infrared region, but no response was found under visible light. The embedded IrP 2 nanoparticles act as trap centers inducing photogating in the device, and the average trap state energy was estimated to be ∼16.5 ± 1.5 meV from the temperature-dependent photocurrent studies. The device was found to be immune to air exposure and bending, suggestive of use a a wearable sensor.

Diabetes is a type of disease that threatens human health, which can be diagnosed based on the level of glucose in the blood. Recently, various MOF-based materials have been developed as efficient electrochemical glucose sensors because of their tunable pore channels, large specific surface area well dispersed metallic active sites, etc. In this review, the significance of glucose detection and the advantages of MOF-based materials for this application are primarily discussed. Then, the application of MOF-based materials can be categorized into two types of glucose sensors: enzymatic biosensors and non-enzymatic sensors. Finally, insights into the current research challenges and future breakthrough possibilities regarding electrochemical glucose sensors are considered.

The properties and, hence, the application of materials are dependent on the way their constituent atoms are arranged. Here, we report a facile approach to produce body-centered cubic (bcc) and face-centered cubic (fcc) phases of bimetallic FeCo crystalline nanoparticles embedded into nitrogen-doped carbon nanotubes (NCNTs) with equal loading and almost similar particle size for both crystalline phases by a rational selection of precursors. The two electrocatalysts with similar composition but different crystalline structures of the encapsulated nanoparticles have allowed us, for the first time, to account for the effect of crystal structure on the overall work function of electrocatalysts and the concomitant correlation with the oxygen reduction reaction (ORR). This study unveils that the electrocatalysts with lower work function show lower activation energy to facilitate the ORR. Importantly, the difference between the ORR activation energy on electrocatalysts and their respective work functions are found to be identical (∼0.2 eV). A notable decrease in the ORR activity after acid treatment indicates the significant role of encapsulated FeCo nanoparticles in influencing the oxygen electrochemistry by modulating the material property of overall electrocatalysts.

High-entropy alloys (HEAs) with five or more elements can provide near-continuous adsorption energies and can be optimized for superior persistent catalytic activity. This report presents electrochemical water oxidation facilitated by employing graphene and FeCoNiCuCr HEA nanoparticle based composites prepared via the mechanical milling of graphite-metal powders. The composite efficiently facilitates water oxidation with a low overpotential of 330 mV at 10 mA cm-2, and high specific and mass activities (∼143 mA cm-2 and 380 mA mg-1, respectively, at 1.75 V). Importantly, the composites exhibit excellent accelerated cycling stability with ∼99% current retention (after 3250 cycles). The HEA-based composites are anticipated to replace noble/precious metal based traditional electrocatalysts in the future, the use of which is a major obstacle in the technological scalability of electrochemical energy conversion and storage devices.

Nonmetallic and metallic heteroatom doped carbonaceous materials have garnered tremendous research attention due to a potential replacement to the precious Pt-group and (Ru, Ir)-oxide based catalysts and are essential part of the next-generation electrode catalysts for fuel cells, electrolyzers, and metal-air batteries. In this regard, we focus on three important categories of carbonaceous material, namely, metal-free heteroatom doped, transition metal heteroatom codoped, and carbon nitride (C 3 N 4 ) based hybrid materials. Implications of various strategies, using one-step pyrolysis technique have been discussed for the effective design of heteroatom modified carbonaceous electrocatalysts. In this minireview, we outline the richness of one-step strategy for designing electrochemically active heteroatom doped carbon, transition metal-heteroatom codoped carbon, and C 3 N 4 derived hybrid materials in the perspective of electrochemical energy conversion and storage devices. We also outline the future research direction in the development of highly efficient and sustainable electrocatalysts for oxygen electrochemistry. Finally, we wind up the article with the challenges and outlook on heteroatoms and transition metal-heteroatom codoped carbon material as an efficient and low-cost electrocatalysts, thereby promoting the development of this important area., Competing Interests: The authors declare no competing financial interest., (© 2020 American Chemical Society.)

Despite the availability and dedicated studies on a variety of carbon nanostructures, amorphous carbon is still a preferred support for a wide range of commercially available metal catalysts. In order to shed some light on this, we carried out electroless deposition of metal nanoparticles on various carbon nanostructures such as amorphous carbon (a-C), carbon nanotubes (CNTs), and nitrogen-doped CNTs (NCNTs) under similar experimental conditions. The main objective is to elucidate the preferable deposition on a particular carbon nanostructure, if any, and understand the underlying mechanism. Experimental results unveil preferred electroless deposition of metal nanoparticles on a-C over CNTs and NCNTs. Notably, the deposition is nicely correlated with the position of the Fermi level ( E F ) with respect to the M n + ↔ M 0 redox level ( E 0 ). Remarkably, E F is found to be in the following order NCNT > CNT > a-C and the smaller gap ( E 0 - E F ) favors the faster electron transfer, resulting in the preferential reduction of M n + , yielding finer nanoparticles on a-C. We believe that this approach can pave the way for designing noble metal-based carbon nanocomposites for a variety of applications, ranging from environmental redemption to electrochemical energy harvesting. As case studies, we have explored the nanocomposites for various catalytic activities and found them to be very competent with recently reported various state-of-the-art electrocatalysts and their commercial counterparts.

One of the most common functional groups encountered in drug molecules is the amide, and the most common degradation pathway for amides is base-mediated hydrolysis to its constituent amine and carboxylic acid. Herein, we report for the first time, a base-mediated oxidative degradation pathway of secondary amides to primary amides. This transformation also represents a novel synthetic methodology, reported for the first time in this work, in transforming secondary amides to primary amides without using any oxidative reagents. The introduction of this mechanism into the pharmaceutical literature is important given that the mechanism and required reactants are present to carry out the chemistry in dosage forms., (Copyright © 2020 American Pharmacists Association®. Published by Elsevier Inc. All rights reserved.)

Rational engineering of atomically scaled metal-nitrogen-carbon (M-N-C) moieties has been the topic of recent research interest because of their potential application as an electrochemical oxygen reduction reaction (ORR) catalyst. Despite numerous efforts on M-N-Cs, attaining both adequate activity and a satisfactory stability simultaneously is a principal issue. Herein, we demonstrated the synthesis of a single-atom tungsten catalyst supported on the N-doped carbon matrix (W-N-C) and its application as an ORR catalyst. W-N-C was synthesized using the economically viable, simple, one-step pyrolysis of dicyandiamide and tungsten(VI) chloride at moderate temperature (700 °C). The synthesis of W-N-C avoids any post acid treatment as it does not require any subsidiary sacrificial metal like Zn and, hence, does not induce any burden associated with chemical waste management. The atomic dispersion of W atoms stabilized by N-doped porous carbon and the formation of WN 2 C 2 were confirmed by high-angle annular dark-field scanning transmission electron microscopy and X-ray absorption spectroscopy. Interestingly, as-synthesized WN 2 C 2 exhibited unprecedented electrocatalytic activity with a half-wave potential of 764 mV vs reversible hydrogen electrode (RHE) as well as significantly enhanced stability (retaining >99% diffusion-limited current density and the loss in activity is 10.5% at 0.84 V after 10,000 potential cycles), which is much better than the stability limit set by the US Department of Energy in an alkaline medium. Overall, the activity of W-N-C surpasses that of Pt/C after 5000 cycles. The excellent stability is believed to be due to the symmetric coordination of the metal active site (W 2 N 2 C 2 ).

Humidity monitoring has become extremely vital in various technological fields such as environment control, biomedical engineering, and so on. Therefore, a substantial interest lies in the development of fast and highly sensitive devices with high figures of merit. Self-powered and ultrasensitive humidity sensors based on SnS 2 nanofilms of different film thicknesses have been demonstrated in this work. The sensing behavior has been investigated in the relative humidity (RH) range of 2-99%. The observed results reveal a remarkable response and ultrafast detection even with zero applied bias (self-powered mode), with response and recovery times of ~ 10 and ~ 0.7 s, respectively. The self-powered behavior has been attributed to the inhomogeneities and the asymmetry in the contact electrodes. The highest sensitivity of ~ 5.64 × 10 6 % can be achieved at an applied bias of 5 V. This approach of fabricating such highly responsive, self-powered and ultrafast sensors with simple device architectures will be useful for designing futuristic sensing devices.

The study reports the optimized incorporation of pyridinic nitrogen in nitrogen-doped carbon nanotubes (CNTs) to realize effective Fe-N x centers throughout the framework. The study unveils nitrogen as a valuable asset to promote the homogeneous dispersion of Fe moieties throughout the CNT framework, which is a necessary component to institute uniform Fe-N x centers. In addition, pyridinic nitrogen causes disruption in strongly delocalized π-electrons, which impart electron-withdrawing nature in the carbon matrix, resulting in an anodic shift in oxygen reduction reaction (ORR) onset potential ( E onset ). The direct interaction of Fe-N x with O 2 , as evidenced by poisoning and computational studies, ensures the preferential inner sphere electron transfer mechanism. Despite the alkaline medium, the outer sphere electron transfer mechanism was muted, with suppressed HO 2 - generation, preferential 4e - reduction pathways, and excellent cyclic stability. The study indicates the dependency of ORR half-wave potential on the electron transfer mechanism. The poisoning study unveils the direct involvement of Fe-N x electroactive centers in facilitating ORR in alkaline medium. It further indicates a noticable increase (up to ∼25%) in peroxide generation-an unwanted ORR intermediate-and concomitant reduction in average electron transfer no. per oxygen molecule.

While band gap and absorption coefficients are intrinsic properties of a material and determine its spectral range, response time is mainly controlled by the architecture of the device and electron/hole mobility. Further, 2D-layered materials such as transition metal dichalogenides (TMDCs) possess inherent and intriguing properties such as a layer-dependent band gap and are envisaged as alternative materials to replace conventional silicon (Si) and indium gallium arsenide (InGaAs) infrared photodetectors. The most researched 2D material is graphene with a response time between 50 and 100 ps and a responsivity of <10 mA/W across all wavelengths. Conventional Si photodiodes have a response time of about 50 ps with maximum responsivity of about 500 mA/W at 880 nm. Although the responsivity of TMDCs can reach beyond 10 4 A/W, response times fall short by 3-6 orders of magnitude compared to graphene, commercial Si, and InGaAs photodiodes. Slow response times limit their application in devices requiring high frequency. Here, we highlight some of the recent developments made with visible and near-infrared photodetectors based on two dimensional SnSe 2 and MoS 2 materials and their performance with the main emphasis on the role played by the mobility of the constituency semiconductors to response/recovery times associated with the hetero-structures.

Oxides are envisioned as promising catalysts to facilitate water oxidation, and the benign presence of hydroxide moieties can further enhance the catalyst performance. However, the nature of synergy between oxides and hydroxides remains elusive. In this study, we have designed a one-pot solution growth technique for the synthesis of flower-shaped N-doped-C-enveloped NiCo 2 O 4 /Ni x Co (1- x ) (OH) y catalysts with varying oxide and hydroxide contents and investigated their water oxidation behavior. The correlation between performance-determining parameters involved in water oxidation, such as the onset potential and overpotential with oxide and/or hydroxide content, oxidation states (oxides), and elemental composition (Co/Ni content), and the possible ways to achieve their optimal values are discussed in detail. Our observations conclude that the onset potential and overpotential are minimal for the hybrid oxide-hydroxide bimetallic system compared with pristine hydroxide or oxide. The optimal hybrid catalyst shows excellent current density, low Tafel slope (82 mV/dec), and low onset potential (281 mV at 2 mA/cm 2 ) and overpotential (348 mV at 10 mA/cm 2 ), besides enduring operational stability in alkaline medium. The low Tafel slope suggests the preferable kinetics for water oxidation, and the poisoning study reveals the direct involvement of metal as active sites. The overall study unveils the synergy in the Co-Ni-based binary transition-metal oxide-hydroxide hybrid, which makes it a potential candidate for water oxidation catalysts, and hence, it is expected that the hybrid will find applications in energy conversion devices, such as electrolyzers.

Here, Pd-coated Ru nanocrystals supported on N-doped graphene (Pd-Ru@NG) are obtained via electroless deposition of Pd on Ru nanocrystals. We have demonstrated that Pd boosts the electrocatalytic performance of Pd-Ru@NG towards the hydrogen evolution reaction (HER) and alcohol tolerant oxygen reduction reaction (ORR) as compared to Pt/C.

Here, we demonstrate improved NO 2 gas sensing properties based on reduced graphene oxide (rGO) decorated V 2 O 5 thin film. Excluding the DC sputtering grown V 2 O 5 thin film, rGO was spread over V 2 O 5 thin film by the drop cast method. The formation of several p-n heterojunctions was greatly affected by the current-voltage relation of the rGO-decorated V 2 O 5 thin film due to the p-type and n-type nature of rGO and V 2 O 5 , respectively. Initially with rGO decoration on V 2 O 5 thin film, current decreased in comparison to the pristine V 2 O 5 thin film, whereas depositing rGO film on a glass substrate drastically increased current. Among all sensors, only the rGO-decorated V 2 O 5 sensor revealed a maximum NO 2 gas sensing response for 100 ppm at 150 °C, and it achieved an approximately 61% higher response than the V 2 O 5 sensor. The elaborate mechanism for an extremely high sensing response is attributed to the formation and modulation of p-n heterojunctions at the interface of rGO and V 2 O 5 . In addition, the presence of active sites like oxygenous functional groups on the rGO surface enhanced the sensing response. On that account, sensors based on rGO-decorated V 2 O 5 thin film are highly suitable for the purpose of NO 2 gas sensing. They enable the timely detection of the gas, further protecting the ecosystem from its harmful effects.

The ability to produce and isolate relatively pure amounts of relevant degradation products is key to several aspects of drug product development: (a) aid in the unambiguous structural identification of such degradation products, fulfilling regulatory requirements to develop safe formulations (International Conference on Harmonization Q3B and M7); (b) pursue as appropriate safety evaluations with such material, such as chronic toxicology or Ames testing; (c) for a specified degradation product in a late-stage regulatory filing, use pure and well-characterized material as the analytical standard. Producing such materials is often a resource- and time-intensive activity, either relying on the isolation of slowly formed degradation products from stressed drug product or by re-purposing the drug substance synthetic route. This problem is exacerbated if the material of interest is an oxidative degradation product, because typical oxidative stressing (H 2 O 2 and radical initiators) tends to produce a myriad of irrelevant species beyond a certain stress threshold, greatly complicating attempts for isolating the relevant degradation product. In this article, we present reagents and methods that may allow the rapid and selective enrichment of active pharmaceutical ingredient with the desired oxidative degradation product, which can then be isolated and used for purposes described above., (Copyright © 2019 American Pharmacists Association®. Published by Elsevier Inc. All rights reserved.)

A self-powered, broad band and ultrafast photodetector based on n + -InGaN/AlN/n-Si(111) heterostructure is demonstrated. Si-doped (n + type) InGaN epilayer was grown by plasma-assisted molecular beam epitaxy on a 100 nm thick AlN template on an n-type Si(111) substrate. The n + -InGaN/AlN/n-Si(111) devices exhibit excellent self-powered photoresponse under UV-visible (300-800 nm) light illumination. The maximum response of this self-powered photodetector is observed at 580 nm for low-intensity irradiance (0.1 mW/cm 2 ), owing to the deep donor states present near the InGaN/AlN interface. It shows a responsivity of 9.64 A/W with rise and fall times of 19.9 and 21.4 μs, respectively. A relation between the open circuit voltage and the responsivity has been realized.

In photodetection, the response time is mainly controlled by the device architecture and electron/hole mobility, while the absorption coefficient and the effective separation of the electrons/holes are the key parameters for high responsivity. Here, we report an approach toward the fast and highly responsive infrared photodetection using an n-type SnSe 2 thin film on a p-Si(100) substrate keeping the overall performance of the device. The I- V characteristics of the device show a rectification ratio of ∼147 at ±5 V and enhanced optoelectronic properties under 1064 nm radiation. The responsivity is 0.12 A/W at 5 V, and the response/recovery time constants were estimated as ∼57 ± 25/34 ± 15 μs, respectively. Overall, the response times are shown to be controlled by the mobility of the constituent semiconductors of a photodiode. Further, our findings suggest that n-SnSe 2 can be integrated with well-established Si technology with enhanced optoelectronic properties and also pave the way in the design of fast response photodetectors for other wavelengths as well.

Despite the recent promise of transition metal carbides as nonprecious catalysts for the hydrogen evolution reaction (HER), their extension to the oxygen evolution reaction (OER) to achieve the goal of overall water splitting remains a significant challenge. Herein, a new Ni/Mo x C (MoC, Mo 2 C) nanoparticle-supported N-doped graphene/carbon nanotube hybrid (NC) catalyst is developed via a facile, one-step integrated strategy, which can catalyze both the HER and OER in an efficient and robust manner. The catalyst affords low overpotentials of 162 and 328 mV to achieve a current density of 10 mA/cm 2 for HER and OER, respectively, in alkaline medium, which either compares favorably or exceeds most of the Mo-based catalysts documented in the literature. It is believed that there is an electronic synergistic effect among Mo x C, Ni, and NC, wherein a tandem electron transfer process (Ni → Mo x C → NC) may be responsible for promoting the HER as well as OER activity. This work opens a new avenue toward the development of multicomponent, highly efficient but inexpensive electrocatalysts for overall water splitting.

Here, we report a simple technique that uses mesoporous SnO 2 to monitor the water quality and degrade the hazardous organic pollutants simultaneously. The technique generates hydroxyl radicals and a voltage that is hindered by the presence of hazardous organic pollutants. Pollutant as low as 1 ppb concentration level can easily be detected. The developed system not only monitors the water quality but also is capable of degrading hazardous dyes (organic pollutants) through its self-power, not relying on any external stimuli such as light, heat, radiation, and current. A simple digital laboratory multimeter is shown to be useful for the overall study. Overall, the study indicates that spectrophotometer generally used to monitor the dye concentration can be avoided.

Nonpolar a-plane GaN epitaxial films were grown on an r-plane sapphire using the plasma-assisted molecular beam epitaxy system, with various nitrogen plasma power conditions. The crystallinity of the films was characterized by high-resolution X-ray diffraction and reciprocal space mapping. Using the X-ray "rocking curve-phi scan", [0002], [1-100], and [1-102] azimuth angles were identified, and interdigitated electrodes along these directions were fabricated to evaluate the direction-dependent UV photoresponses. UV responsivity ( R) and internal gain ( G) were found to be dependent on the azimuth angle and in the order of [0002] > [1-102] > [1-100], which has been attributed to the enhanced crystallinity and lowest defect density along [0002] azimuth. The temporal response was very stable irrespective of growth conditions and azimuth angles. Importantly, response time, responsivity, and internal gain were 210 ms, 1.88 A W -1 , and 648.9%, respectively, even at a bias as low as 1 V. The results were validated using the Silvaco Atlas device simulator, and experimental observations were consistent with simulated results. Overall, the photoresponse is dependent on azimuth angles and requires further optimization, especially for materials with in-plane crystal anisotropy.

In this work, a promising strategy to increase the broadband solar light absorption was developed by synthesizing a composite of metal-free carbon nitride-carbon dots (C 3 N 4 -C dots) and plasmonic titanium nitride (TiN) nanoparticles (NPs) to improve the photoelectrochemical water-splitting performance under simulated solar radiation. Hot-electron injection from plasmonic TiN NPs to C 3 N 4 played a role in photocatalysis, whereas C dots acted as catalysts for the decomposition of H 2 O 2 to O 2 . The use of C dots also eliminated the need for a sacrificial reagent and prevented catalytic poisoning. By incorporating the TiN NPs and C dots, a sixfold improvement in the catalytic performance of C 3 N 4 was observed. The proposed approach of combining TiN NPs and C dots with C 3 N 4 proved effective in overcoming low optical absorption and charge recombination losses and also widens the spectral window, leading to improved photocatalytic activity.

Highly porous materials, with large surface area and accessible space, variable chemical compositions, and porosity at different length scales, have captivated the attention of researchers in recent years as an important family of functional materials. Here, we report a novel approach to grow porous metal oxides (PMOs) by sequential elemental dealloying in which a highly mobile element gets dealloyed first under the thermal treatment (annealing) and facilitates the formation of PMOs. Subsequently, a chemiresistive sensor based on porous SnO 2 was fabricated for humidity sensing at room temperature which shows a high sensitivity of 348 in a fully humid [>99% relative humidity (RH)] atmosphere with an accuracy of 1% RH change. In addition, the sensor is highly durable and reproducible. Eventually, the chemiresistive sensor has been exploited for electronic listening toward speaking, whistling, and breath monitoring. Overall, the results advocate the fabrication of PMOs and the development of resistive humidity sensors for electronic listening as well as for biomedical applications.

We, for the first time, provide the experimental demonstration on the band gap engineering of layered hexagonal SnSe 2 nanostructured thin films by varying the thickness. For 50 nm thick film, the band gap is ~2.04 eV similar to that of monolayer, whereas the band gap is approximately ~1.2 eV similar to that of bulk for the 1200 nm thick film. The variation of the band gap is consistent with the the theoretically predicted layer-dependent band gap of SnSe 2 . Interestingly, the 400-1200 nm thick films were sensitiveto 1064 nm laser iradiation and the sensitivity increases almost exponentiallly with thickness, while films with 50-140 nm thick are insensitive which is due to the fact that the band gap of thinner films is greater than the energy corresponding to 1064 nm. Over all, our results establish the possibility of engineering the band gap of SnSe 2 layered structures by simply controlling the thickness of the film to absorb a wide range of electromagnetic radiation from infra-red to visible range.

Cold emission properties of carbon nanodots (CNDs) evaluated using ANSYS Maxwell software are predicted to be size-dependent and then verified experimentally. In order to correlate the electron emission properties with the size of CNDs, the work function values were determined using ultraviolet photoelectron spectroscopy. This is the first report on theoretical calculations based on density functional theory and experimental results that confirm the work function dependency on the charge state of the functional group attached on the particle surface. The smallest CND (2.5 nm) has the highest percentage of negatively charged groups as well as the lowest work function (5.18 eV). The smallest dimension with the lowest work function assures that this sample is the best suited for field emission. It shows excellent field emission properties with a high current density of ∼1.45 mA cm -2 at 2 V μm -1 electric field, turn-on field as low as 0.04 V μm -1 , very high field enhancement factor of 2.7 × 10 5 and high stability. Overall, the zero-dimensional CNDs showed superior field emission activity as compared to the higher dimensional carbon nanomaterials.

Geometrical tunability offers sharp edges and an open-armed structure accompanied with a high electrochemical active surface area to ensure the efficient and effective utilization of materials by exposing the electrochemical active sites for facile accessibility of reactant species. Herein, we report a one-step, single-pot, surfactant-free, electroless, and economic route to synthesize palladium sulfide nanostructures with different geometries at mild temperatures and their catalytic properties towards the oxygen reduction reaction (ORR) and methanol electro-oxidation (MOR). For ORR, the positive on-set, half wave potentials, smaller Tafel slope, high electrochemical active surface area, large roughness factor, and better cyclic stability of the proposed nanostructures as compared to those of the commercial state-of-the-art Pt-C/PdS catalysts suggest their superiority in an alkaline medium. In addition, high mass activity (J f ∼ 715 mA mg -1 ), in comparison with that of the commercial state-of-the-art Pt-C/PdS catalysts (J f ∼ 138/41 mA mg -1 , respectively), and high J f /J b (1.52) along with the superior operational stability of the multi-arm palladium sulfide nanostructures towards MOR advocates the bi-functional behavior of the catalyst and its potential as a promising Pt-free anode/cathode electrocatalyst in fuel cells.

Here, we report on the novel design of dual emission via defect state engineering in codoped oxide microstructures and its implication in fluorescence intensity ratio (FIR) based optical temperature sensing. Eu- and Er-co-doped ZnO (EuEr:ZnO) microrods prepared by hydrothermal method. The emission peaks corresponding to Eu 3+ and Er 3+ are observed suggesting dual emission from codoped ZnO. Interestingly, Er 3+ peak intensity decreases and that of Eu 3+ increases with increase of temperature as is the case of individual doped cases and dual emission is also achieved via phyical mixing of the individual doped ZnO. The opposite trend is due to the electron transfer from the defect levels of host ZnO to Eu 3+ and not to Er 3+ . Overall, our results pave the way in designing dual emission that can be exploited in FIR based temperature sensing. As an example, we probe temperature dependency of congo-red and polyvinyle alcohol (PVA) composite using EuEr:ZnO as optical probe for temperature sensing.

Metal ions play an important role in oxidative drug degradation. One of the most ubiquitous metal ion impurities in excipients and buffers is Fe(III). In the field of oxidative drug degradation chemistry, the role of Fe(III) has been primarily discussed in terms of its effect in reaction with trace hydroperoxide impurities. However, the role of Fe(III) acting as a direct oxidant of drug molecules, which could operate in the absence of any hydroperoxide impurities, is less common. This work focuses on Fe(III)-induced oxidation of some aromatic drug molecules/drug fragments containing benzylic C-H bonds in the absence of initiating peroxides. Alcohol and ketone degradates are formed at the benzylic carbon atom. The formation of a π-stabilized cation radical is postulated as the key intermediate for the downstream oxidation. Implications are briefly discussed., (Copyright © 2017 American Pharmacists Association®. Published by Elsevier Inc. All rights reserved.)

Background: NGF signaling through TrkA triggers pathways involved in a wide range of biological effects. Clinical trials targeting either NGF or TrkA are ongoing to treat various diseases in the areas of oncology, neuroscience, and for pain, but there is no described measure of target engagement of TrkA in these studies., New Method: We have developed custom ELISA assays to measure NGF-induced phosphorylation of TrkA specific for rodent and human receptors. Optimized tissue processing methods allow for detection in both the brain and in skin. In addition, TrkB and TrkC assays have been in established to evaluate selectivity against other neurotrophin receptors., Results: In a preclinical NGF-induced pain model, we show that pre-dosing with a TrkA inhibitor prevents phosphorylation of TrkA in the skin at a dose that is efficacious in reversal of thermal hypersensitivity. In addition, we show data in non-human primate and human skin supporting the potential use of this approach to enable translational target engagement. Comparison with existing methods: Existing methods involve animal models expressing TrkA tumors or injection of over-expressing TrkA recombinant cells into animals. Our method can measure target engagement in both normal and disease tissues in preclinical animal models and human skin., Conclusions: We have developed methods to assess target engagement for drug programs aimed at disrupting NGF-induced TrkA signaling. This includes preclinical determination of selectivity against other neurotrophin receptors and estimation of functional peripheral restriction. Preliminary data supports this method can be translated into a clinical pharmacodynamic readout using human skin biopsies., (Copyright © 2017 Elsevier B.V. All rights reserved.)

Positively charged functionalized carbon nanodots (CNDs) with a variety of different effective surface areas (ESAs) are synthesized via a cheap and time effective microwave method and applied for the generation of hydrogen via hydrolysis of sodium borohydride. To the best of our knowledge, this is the first report of metal-free controlled hydrogen generation. Our observation is that a positively charged functional group is essential for the hydrolysis for hydrogen production, but the overall activity is found to be enhanced with the ESA. A maximum value of 1066 ml g -1 min -1 as the turnover frequency is obtained which is moderate in comparison to other catalysts. However, the optimum activation energy is found to be 22.01 kJ mol -1 which is comparable to well-known high cost materials like Pt and Ru. All of the samples showed good reusability and 100% conversion even after the 10th cycle. The effect of H + and OH - is also studied to control the on-board and on-demand hydrogen production ("on-off switching"). It is observed that H 2 production decreases inversely with NaOH concentration and ceases completely when 10 -1 M NaOH is added. With the addition of HCl, H 2 production can be initiated again, which confirms the on/off control over production.

Selective inhibition of Kv1.5, which underlies the ultra-rapid delayed rectifier current, I Kur , has been pursued as a treatment for atrial fibrillation. Here we describe the discovery of MK-1832, a Kv1.5 inhibitor with improved selectivity versus the off-target current I Ks , whose inhibition has been associated with ventricular proarrhythmia. MK-1832 exhibits improved selectivity for I Kur over I Ks (>3000-fold versus 70-fold for MK-0448), consistent with an observed larger window between atrial and ventricular effects in vivo (>1800-fold versus 210-fold for MK-0448). MK-1832 also exhibits an improved preclinical pharmacokinetic profile consistent with projected once daily dosing in humans., (Copyright © 2017 Elsevier Ltd. All rights reserved.)

Background and Aims: Non-alcoholic fatty liver disease (NAFLD) is the most common chronic liver disease and is closely related to metabolic syndrome and its risk factors. Worldwide, epidemiological studies have reported NAFLD prevalence rates of 5% to 30% depending on geographical variations. While epidemiological data suggest a progressively increasing prevalence of metabolic risk factors in Singapore, there are limited data about NAFLD per se in the community. We aim to explore the prevalence and perceptions of NAFLD in Singapore., Methods: Attendees at a gastroenterology public forum were enrolled in a cross-sectional observational study evaluating demographic, anthropometric and clinical information. The diagnosis of NAFLD was based on sonographic criteria. Metabolic syndrome was defined according to International Diabetes Federation guidelines. Perceptions of NAFLD were explored using a self-administered survey questionnaire., Results: A total of 227 subjects were recruited, with NAFLD being diagnosed in 40% of the cohort. Relative to those without NAFLD, subjects with NAFLD had higher male preponderance, older age, higher body mass index, waist circumference and more metabolic syndrome (all P < 0.05). Although 71.2% subjects had heard about NAFLD before, only 25.4% of them felt that they were at risk of NAFLD. Comparable responses were observed in subjects with no metabolic risk factors relative to subjects with one or more metabolic risk factors (P > 0.05). Of note, 75.6% of subjects with one or more metabolic risk factors did not think that they were at risk of NAFLD., Conclusion: Our study suggests a significant local prevalence of NAFLD in the community including non-obese individuals. Considering the tendency to underestimate risk of NAFLD, enhanced public education about NAFLD is warranted to improve understanding., (© The Author(s) 2015. Published by Oxford University Press and the Digestive Science Publishing Co. Limited.)

Here, we demonstrate a green and environment-friendly pyrolysis route for the synthesis of metal-rich sulphide embedded in an N-doped carbon (NC) framework in the absence of sulphide ions (S(2-)). The metal-chelate complex (tris(ethylenediamine) metal(ii) sulfate) serves as a new and single source precursor for the synthesis of earth abundant and non-precious hybrid structures such as metal-rich sulphides Co9S8@NC and Ni3S2@NC when M(II) = Co(2+) and Ni(2+) and counter sulphate (SO4(2-)) ions are the source of S. Both the hybrids show superior OER activity as compared to commercial RuO2.

Herein, we describe the development of a functionally selective liver X receptor β (LXRβ) agonist series optimized for Emax selectivity, solubility, and physical properties to allow efficacy and safety studies in vivo. Compound 9 showed central pharmacodynamic effects in rodent models, evidenced by statistically significant increases in apolipoprotein E (apoE) and ATP-binding cassette transporter levels in the brain, along with a greatly improved peripheral lipid safety profile when compared to those of full dual agonists. These findings were replicated by subchronic dosing studies in non-human primates, where cerebrospinal fluid levels of apoE and amyloid-β peptides were increased concomitantly with an improved peripheral lipid profile relative to that of nonselective compounds. These results suggest that optimization of LXR agonists for Emax selectivity may have the potential to circumvent the adverse lipid-related effects of hepatic LXR activity.

A visible light driven, direct Z-scheme reduced graphene oxide-Ag3PO4 (RGO-Ag3 PO4 ) heterostructure was synthesized by means of a simple one-pot photoreduction route by varying the amount of RGO under visible light illumination. The reduction of graphene oxide (GO) and growth of Ag3PO4 took place simultaneously. The effect of the amount of RGO on the textural properties and photocatalytic activity of the heterostructure was investigated under visible light illumination. Furthermore, total organic carbon (TOC) analysis confirmed 97.1 % mineralization of organic dyes over RGO-Ag3PO4 in just five minutes under visible-light illumination. The use of different quenchers in the photomineralization suggested the presence of hydroxyl radicals ((.)OH), superoxide radicals ((.)O2 (-)), and holes (h(+)), which play a significant role in the mineralization of organic dyes. In addition to that, clean hydrogen fuel generation was also observed with excellent reusability. The 4 RGO-Ag3PO4 heterostructure has a high H2 evolution rate of 3690 μmol h(-1)  g(-1), which is 6.15 times higher than that of RGO., (© 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

We report the temperature-dependent photoluminescence (PL) properties of polymeric graphite-like carbon nitride (g-C3N4) and a methodology for the determination of quantum efficiency along with the activation energy. The PL is shown to originate from three different pathways of transitions: σ*-LP, π*-LP, and π*-π, respectively. The overall activation energy is found to be ∼73.58 meV which is much lower than the exciton binding energy reported theoretically but ideal for highly sensitive wide-range temperature sensing. The quantum yield derived from the PL data is 23.3%, whereas the absolute quantum yield is 5.3%. We propose that the temperature-dependent PL can be exploited for the evaluation of the temperature dependency of quantum yield as well as for temperature sensing. Our analysis further indicates that g-C3N4 is well-suited for wide-range temperature sensing.