The Dual-Site Adsorption and High Redox Activity Enabled by Hybrid Organic-Inorganic Vanadyl Ethylene Glycolate for High-Rate and Long-Durability Lithium-Sulfur Batteries.

Transition metal oxides (TMOs) have attracted considerable attention owing to their strong anchoring ability and natural abundance. However, their single-site adsorption toward sulfur (S) species significantly lowers the possibility of S species reacting with Li+ in the electrolyte and increases the reaction barrier. This study investigates molecular modification by coupling the TMO structure with Li+ conductive polymer ligands, and vanadyl ethylene glycolate (VEG) is successfully synthesized by introducing organic ligands into the VOx crystal structure. In addition to the strong interaction between the VOx and lithium polysulfides via the V-S bond, the groups in the VEG polymer ligands can reversibly couple/decouple with Li+ in the electrolyte. Such dual-site adsorption enables a smooth dynamic adsorption-diffusion process. Accordingly, the VEG-based Li-S cells exhibit excellent rate reversibility, cyclic stability, and a long cycle life without the addition of conducting agents. Encouragingly, the VEG-based cells also exhibit close and excellent capacity decays of 0.081%, 0.078%, and 0.095% at 0, 25, and 50 °C (1 C for 200 cycles), respectively. This work provides a novel approach for developing advanced catalysts that can realize Li-S batteries with long-term durability, fast charge-discharge properties, and applications in a wide temperature range.

ZnWO4 nanorod-colloidal SnO2 quantum dots core@shell heterostructures: Efficient solar-light-driven photocatalytic degradation of tetracycline.

Zinc tungsten oxide (ZW) and colloidal SnO2 quantum dots (CS) were synthesized individually by hydrothermal and wet chemical methods. ZW-CS core@shell nanorods were prepared using a sonochemical method for the enhanced photocatalytic activity of tetracycline (TC) degradation. ZW-CS core@shell nanorods were systematically characterized by structural, morphological mapping and optical techniques. All characterization techniques were synchronized to confirm the construction of core@shell nanorods. Optical absorption studies indicate an increased light-capturing efficiency along with a reduced bandgap from 3.56 to 3.23 eV, which is further supported by photoluminescence. Mapping analysis from SEM and HR-TEM evidence the presence of elements as well as a core@shell nanostructure. The optimized sample of ZW-CS 1.0 shows improved photocatalytic degradation of TC under stimulated solar light. The TC degradation efficiency by ZW-CS 1.0 core@shell nanorods was about 97% within 2 h. The formation of core@shell nanorod structure might be the reason for the better photocatalytic tetracycline degradation performance.

Semi-Polycrystalline Polyaniline-Activated Carbon Composite for Supercapacitor Application.

We report on the synthesis of activated carbon-semi-polycrystalline polyaniline (SPani-AC) composite material using in-situ oxidative polymerization of aniline on the carbon surface in an aqueous HCl medium at an elevated temperature of 60 °C. The electroactive polymeric composite material exhibits a uniformly distributed spindle-shaped morphology in scanning electron microscopy (SEM) and well-defined crystallographic lattices in the high-resolution transmission electron microscopy (TEM) images. The X-ray diffraction (XRD) spectrum reveals sharp peaks characteristic of crystalline polyaniline. The characteristic chemical properties of polyaniline are recorded using laser Raman spectroscopy. The cyclic voltammetry curves exhibit features of surface-redox pseudocapacitance. The specific capacitance calculated for the material is 507 F g-1 at the scan rate of 10 mV s-1. The symmetrical two-electrodes device exhibits a specific capacitance of 45 F g-1 at a current density of 5 A g-1. The capacitive retention calculated was found to be 96% up to 4500 continuous charge-discharge cycles and observed to be gradually declining at the end of 10,000 cycles. On the other hand, Coulombic efficiency was observed to be retained up to 85% until 4500 continuous charge-discharge cycles which declines up to 72% at the end of 10,000 cycles. The article also presents a detailed description of material synthesis, the formation of polyaniline (Pani) chains, and the role of material architecture in the performance as surface redox supercapacitor electrode.

Steady-state protein focusing in carrier ampholyte-based isoelectric focusing: Part II-validation and case studies.

In this study, we systematically investigate the validity and applicability of an analytical model developed for carrier ampholyte-based isoelectric focusing (IEF). Three different IEF cases are considered in order to evaluate the efficacy of the approximate analytical results by comparison with high-resolution computer simulations. In the first case, three proteins are separated in a narrow pH range (6-9) by using 50 carrier ampholytes. In the second and third cases, the separation of proteins is studied in broad pH range (3-10) IEF by using 100 carrier ampholytes. Results obtained from the approximate analytical models are in very good agreement with the numerical results for IEF separation of cardiac troponin I, albumin, and hemoglobin in both narrow and broad pH ranges. The sensitivity of the analytical model is also tested for different initial mass ratios of proteins to ampholytes. No appreciable differences are observed between the approximate analytical and numerical results within the mass ratio range studied. The effect of a nominal electric field and/or a nominal pH gradient on protein focusing is also examined to demonstrate the effectiveness of the analytical model. Our results indicate that the use of both nominal electric field and pH gradient will result in erroneous peak concentrations for proteins. Finally, we describe the limitations of the approximate analytical solutions.

Steady-state protein focusing in carrier ampholyte based isoelectric focusing: Part I-Analytical solution.

The determination of an analytical solution to find the steady-state protein concentration distribution in IEF is very challenging due to the nonlinear coupling between mass and charge conservation equations. In this study, approximate analytical solutions are obtained for steady-state protein distribution in carrier ampholyte based IEF. Similar to the work of Svensson, the final concentration profile for proteins is assumed to be Gaussian, but appropriate expressions are presented in order to obtain the effective electric field and pH gradient in the focused protein band region. Analytical results are found from iterative solutions of a system of coupled algebraic equations using only several iterations for IEF separation of three plasma proteins: albumin, cardiac troponin I, and hemoglobin. The analytical results are compared with numerically predicted results for IEF, showing excellent agreement. Analytically obtained electric field and ionic conductivity distributions show significant deviation from their nominal values, which is essential in finding the protein focusing behavior at isoelectric points. These analytical solutions can be used to determine steady-state protein concentration distribution for experiment design of IEF considering any number of proteins and ampholytes. Moreover, the model presented herein can be used to find the conductivity, electric field, and pH field.

Efficient algorithm for simulation of isoelectric focusing.

IEF simulation is an effective tool to investigate the transport phenomena and separation performance as well as to design IEF microchip. However, multidimensional IEF simulations are computationally intensive as one has to solve a large number of mass conservation equations for ampholytes to simulate a realistic case. In this study, a parallel scheme for a 2D IEF simulation is developed to reduce the computational time. The calculation time for each equation is analyzed to identify which procedure is suitable for parallelization. As expected, simultaneous solution of mass conservation equations of ampholytes is identified as the computational hot spot, and the computational time can be significantly reduced by parallelizing the solution procedure for that. Moreover, to optimize the computing time, electric potential behavior during transient state is investigated. It is found that for a straight channel the transient variation of electric potential along the channel is negligible in a narrow pH range (5∼8) IEF. Thus the charge conservation equation is solved for the first time step only, and the electric potential obtain from that is used for subsequent calculations. IEF simulations are carried out using this algorithm for separation of cardiac troponin I from serum albumin in a pH range of 5-8 using 192 biprotic ampholytes. Significant reduction in simulation time is achieved using the parallel algorithm. We also study the effect of number of ampholytes to form the pH gradient and its effect in the focusing and separation behavior of cardiac troponin I and albumin. Our results show that, at the completion of separation phase, the pH profile is stepwise for lower number of ampholytes, but becomes smooth as the number of ampholytes increases. Numerical results also show that higher protein concentration can be obtained using higher number of ampholytes.

Breaking Barriers to High-Practical Li-S Batteries with Isotropic Binary Sulfiphilic Electrocatalyst: Creating a Virtuous Cycle for Favorable Polysulfides Redox Environments.

Investigations into lithium-sulfur batteries (LSBs) has focused primarily on the initial conversion of lithium polysulfides (LiPSs) to Li2 S2 . However, the subsequent solid-solid reaction from Li2 S2 to Li2 S and the Li2 S decomposition process should be equally prioritized. Creating a virtuous cycle by balancing all three chemical reaction processes is crucial for realizing practical LSBs. Herein, amorphous Ni3 B in synergy with carbon nanotubes (aNi3 B@CNTs) is proposed to implement the consecutive catalysis of S8(solid) → LiPSs(liquid) → Li2 S(solid) →LiPSs(liquid) . Systematic theoretical simulations and experimental analyses reveal that aNi3 B@CNTs with an isotropic structure and abundant active sites can ensure rapid LiPSs adsorption-catalysis as well as uniform Li2 S precipitation. The uniform Li2 S deposition in synergy with catalysis of aNi3 B enables instant/complete oxidation of Li2 S to LiPSs. The produced LiPSs are again rapidly and uniformly adsorbed for the next sulfur evolution process, thus creating a virtuous cycle for sulfur species conversion. Accordingly, the aNi3 B@CNTs-based cell presents remarkable rate capability, long-term cycle life, and superior cyclic stability, even under high sulfur loading and extreme temperature environments. This study proposes the significance of creating a virtuous cycle for sulfur species conversion to realize practical LSBs.

Effect of annealing environment on the photoelectrochemical water oxidation and electrochemical supercapacitor performance of SnO2 quantum dots.

SnO2 quantum dots (SQD) were prepared by utilizing the soft-chemical approach. The formed SQD's were annealed in two kinds of environments: air and nitrogen (N2). Each annealing environment resulted in significant improvement in the performance of water oxidation and electrochemical supercapacitor performance. The specific capacitance of the SQD's under the N2 annealing process (SQD-N2) shows significantly better electrochemical performance. A specific capacitance of 79.13 F/g was achieved for SQD-N2 sample by applying a current of 1 mA, which was approximately 1.5 times greater than that of the pristine SQD's. A cycle stability of 99.4% over 5000 cycles was achieved by SQD-N2. The process of nitrogen annealing environment brings down the bandgap from 3.37 to 1.9 eV. The SQD-N2 sample shows the highest photocurrent over SQD and SQD-Air samples. From the LSV study, SQD-N2 shows the photocurrent density of 4.82 mA/cm2, which is 1.43 times greater than pristine SQD sample. The nitrogen-annealing environment provides the optimal environment to tune the average crystallite size and crystallinity nature of SQD's to improve the optical properties like bandgap to enhance the water oxidation and also electrochemical performance.

Morphological guided sphere to dendrite BiVO4 for highly efficient organic pollutant removal and photoelectrochemical performance under solar light.

Monoclinic BiVO4 (m-BiVO4) has been reported as promising phase for solar light driven photocatalysis. However, in the case of morphology guided BiVO4 with different synthetic conditions maintaining the m-BiVO4 phase remains a substantial challenge for achieving an efficient photocatalyst driven by solar light. Herein, a simple hydrothermal approach was used to produce well-defined template free m-BiVO4 dendrites with distinct branches for photo catalytically removal of organic pollutant and photocurrent generation. The development of monoclinic dendrite BiVO4 was confirmed after comprehensive structural, morphological, and optical examinations. FE-SEM images of m-BiVO4 revealed transformation of spherical to dendritic morphology with distinct branches by simply changing the HNO3 to NaOH ratios from 2:1 to 2:2, which are named as BVO 2-1 and BVO 2-2, respectively. The BVO 2-2 dendrites exhibited improved activity of 98% towards methylene blue (MB) photodegradation upon simulated solar light irradiation. The BVO 2-2 dendrites photoelectrode showed an outstanding photocurrent density of 1.4245 mAcm-2 than that of the BVO 2-1 spherical photoelectrode (0.7367 mAcm-2). Enhanced photocatalytic and photoelectrochemical action, could be ascribed to the unique morphological changes provides photoactive sites, harvest more light utilization together with higher separation of e-/h+ pairs. Furthermore, photocatalytic mechanism is investigated based on scavenger trapping agent, valence band XPS, UV Visible DRS and PL study. Our findings could pave the way for the development of dendritic nanostructure photocatalysts with improved photocatalytic activity.

Hydrothermal Synthesis of MnWO4@GO Composite as Non-Precious Electrocatalyst for Urea Oxidation.

In this study, manganese tungstate (MW) and MW/graphene oxide (GO) composites were prepared by a facile hydrothermal synthesis at pH values of 7 and 12. X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), and Raman spectroscopy were used for the structural, compositional, and morphological characterization of the nanoparticles (NPs). The XRD analysis revealed that the formation of monoclinic MnWO4 did not have impurities. The SEM and TEM analyses showed that the synthesized NPs were rod-shaped and well-distributed on the GO. The as-synthesized samples can be used as electrocatalysts for the urea oxidation reaction (UOR). The MW@GO-12 electrocatalyst exhibited higher current density values compared to other electrocatalysts. This study provides a new platform for synthesizing inexpensive nanocomposites as promising electrocatalysts for energy storage and conversion applications.

Enhanced solar-light-driven photocatalytic and photoelectrochemical properties of zinc tungsten oxide nanorods anchored on bismuth tungsten oxide nanoflakes.

At present, sustainable water supply and energy generation are the most important challenges faced by humankind globally. Thus, it is crucial to progress ecological techniques for sustainable removal of organic pollutants from wastewater and generation of hydrogen as an alternative to fossil fuels. In this study, zinc tungsten oxide (ZnWO4) nanorods, bismuth tungsten oxide (Bi2WO6) nanoflakes, and Bi2WO6/ZnWO4 (BO-ZO) nanocomposites were prepared via a simple hydrothermal approach. X-ray diffraction, scanning electron microscopy, transmission electron microscopy, high-resolution transmission electron microscopy, diffuse reflectance spectroscopy, and electrochemical analyses were conducted to confirm the formation of the BO-ZO heterostructure. The structural and morphological analyses revealed that the ZnWO4 nanorods were moderately dispersed on the Bi2WO6 nanoflakes. The bandgap tuning of BO-ZO nanocomposite confirmed the establishment of the heterostructure with band bending properties. The BO-ZO nanocomposite could degrade 99.52% of methylene blue (MB) within 60 min upon solar-light illumination. The photoelectrochemical (PEC) measurement results showed that the BO-ZO nanocomposite showed low charge-transfer resistance and high photocurrent response with good stability. The BO-ZO photoanode showed a low charge-transfer resistance of 35.33 Ω and high photocurrent density of 0.1779 mA/cm2 in comparison with Ag/AgCl in a 0.1 M Na2SO3 electrolyte under solar-light illumination. The MB photocatalytic degradation and PEC water oxidation mechanisms of the nanocomposite were investigated.

Urea assisted ceria nanocubes for efficient removal of malachite green organic dye from aqueous system.

This study describes a simple, high-yield, rapid, and inexpensive route for the synthesis of cubic shape-like cerium oxide nanocubes (CeO2 NCs) using different urea concentrations (0.5, 1.0, and 2.0 g) by the hydrothermal method. The synthesized nanocubes (NCs) are labeled as CeO2 NCs-0.5, CeO2 NCs-1.0, and CeO2 NCs-2.0, corresponding to 0.5, 1.0, and 2.0 g of urea, respectively. The synthesized NCs were characterized by FT-IR, UV-visible, XRD, XPS, SEM and HR-TEM analysis. The synthesized NCs were cubic in shape with average sizes of 12, 12, and 13 nm for the CeO2 NCs-0.5, CeO2 NCs-1.0, and CeO2 NCs-2.0, respectively, obtained by the XRD analysis. The catalytic activity of the CeO2 NCs was studied for the purpose of obtaining the reduction of malachite green (MG) in the presence of sodium borohydride (NaBH4) at room temperature.

Ultra-sonication-assisted silver nanoparticles using Panax ginseng root extract and their anti-cancer and antiviral activities.

A simple, inexpensive ultra-sonication method was used to synthesize quasi spherical silver nanoparticles (AgNPs) with an aqueous extract from Panax ginseng roots. This method has the advantages of being completely eco-friendly and allows increased reaction rates, uniform dispersal of the nanoparticles in liquids, and effective breaking of aggregates. Biomolecules present in plant extracts are often used to reduce metal ions to nanoparticles in a single-step green synthesis route. The formation of the AgNPs was characterized using UV-visible (UV-vis) spectroscopy, X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), energy- dispersive X-ray analysis (EDX), Fast Fourier Transform (FFT), and high-resolution transmission electron microscopy (HR-TEM). The formation of AgNPs (456 nm) was confirmed by UV-vis spectroscopy. HR-TEM analysis revealed that most of the AgNPs were quasi spherical with sizes ranging from approximately 5 to 15 nm. The crystalline nature of the AgNPs was confirmed by XRD, and the presence of elemental silver was confirmed by energy-dispersive X -ray analysis. The AgNPs showed dose-dependent cytotoxicity towards HeLa cells in vitro (3.88% at 0.005 M, 5.11% at 0.01 M, 7.52% at 0.015 M, 11.19% at 0.02 M, and 19.45% at 0.025 M) as revealed by sulforhodamine B assay. They were also shown to be virucidal against the influenza A virus (strain A/PR/8). Hence, the present facile, eco-friendly, and efficient method results in the synthesis of AgNPs that can act as an alternative biomaterial for future biomedical applications.

Effect of Joule heating on isoelectric focusing of proteins in a microchannel.

Electric field-driven separation and purification techniques, such as isoelectric focusing (IEF) and isotachophoresis, generate heat in the system that can affect the performance of the separation process. In this study, a new mathematical model is presented for IEF that considers the temperature rise due to Joule heating. We used the model to study focusing phenomena and separation performance in a microchannel. A finite volume-based numerical technique is developed to study temperature-dependent IEF. Numerical simulation for narrow range IEF (6 < pH < 10) is performed in a straight microchannel for 100 ampholytes and two model proteins: staphylococcal nuclease and pancreatic ribonuclease. Separation results of the two proteins are obtained with and without considering the temperature rise due to Joule heating in the system for a nominal electric field of 100 V/cm. For the no Joule heating case, constant properties are used, while for the Joule heating case, temperature-dependent titration curves and thermo-physical properties are used. Our numerical results show that the temperature change due to Joule heating has a significant impact on the final focusing points of proteins, which can lower the separation performance considerably. In the absence of advection and any active cooling mechanism, the temperature increase is the highest at the mid-section of a microchannel. We also found that the maximum temperature in the system is a strong function of the [Formula: see text] value of the carrier ampholytes. Simulation results are also obtained for different values of applied electric fields in order to find the optimum working range considering the simulation time and buffer temperature. Moreover, the model is extended to study IEF in a straight microchip where pH is formed by supplying H(+) and OH(-), and the thermal analysis shows that the heat generation is negligible in ion supplied IEF.

Mathematical and numerical model to study two-dimensional free flow isoelectric focusing.

Even though isoelectric focusing (IEF) is a very useful technique for sample concentration and separation, it is challenging to extract separated samples for further processing. Moreover, the continuous sample concentration and separation are not possible in the conventional IEF. To overcome these challenges, free flow IEF (FFIEF) is introduced in which a flow field is applied in the direction perpendicular to the applied electric field. In this study, a mathematical model is developed for FFIEF to understand the roles of flow and electric fields for efficient design of microfluidic chip for continuous separation of proteins from an initial well mixed solution. A finite volume based numerical scheme is implemented to simulate two dimensional FFIEF in a microfluidic chip. Simulation results indicate that a pH gradient forms as samples flow downstream and this pH profile agrees well with experimental results validating our model. In addition, our simulation results predict the experimental behavior of pI markers in a FFIEF microchip. This numerical model is used to predict the separation behavior of two proteins (serum albumin and cardiac troponin I) in a two-dimensional straight microchip. The effect of electric field is investigated for continuous separation of proteins. Moreover, a new channel design is presented to increase the separation resolution by introducing cross-stream flow velocity. Numerical results indicate that the separation resolution can be improved by three folds in this new design compare to the conventional straight channel design.

Measurement of Critical Structures around Paraclinoidal Area : A Cadaveric Morphometric Study.

OBJECTIVE: Although removal of the anterior clinoid process (ACP) is essential surgical technique, studies about quantitative measurements of the space broadening by the anterior clinoidectomy are rare. The purposes of this study are to investigate the dimension of the ACP, to quantify the improved exposure of the parasellar space after extradural anterior clinoidectomy and to measure the correlation of each structure around the paraclinoidal area. METHODS: Eleven formalin-fixed Korean adult cadaveric heads were used and frontotemporal craniotomies were done bilaterally. The length of C6 segment of the internal carotid artery on its lateral and medial side and optic nerve length were checked before and after anterior clinoidectomy. The basal width and height of the ACP were measured. The relationships among the paraclinoidal structures were assessed. The origin and projection of the ophthalmic artery (OA) were investigated. RESULTS: The mean values of intradural basal width and height of the ACP were 10.82 mm and 7.61 mm respectively. The mean length of the C6 lateral and medial side increased 49%. The mean length of optic nerve increased 97%. At the parasellar area, the lengths from the optic strut to the falciform liament, distal dural ring, origin of OA were 6.69 mm, 9.36 mm and 5.99 mm, respectively. The distance between CN III and IV was 11.06 mm. CONCLUSION: With the removal of ACP, exposure of the C6 segments and optic nerve can expand 49% and 97%, respectively. This technique should be among a surgeon's essential skills for treating lesions around the parasellar area.