Moderate Charge Research Articles

Vasoactive Intestinal Peptide Amphiphile Micelle Chemical Structure and Hydrophobic Domain Influence Immunomodulatory Potentiation.

Vasoactive intestinal peptide (VIP) is a neuropeptide capable of downregulating innate immune responses in antigen presenting cells (APCs) by suppressing their pro-inflammatory cytokine secretion and cell surface marker expression. Though VIP's bioactivity could possibly be leveraged as a treatment for transplant tolerance, drug delivery innovation is required to overcome its intrinsically limited cellular delivery capacity. One option is to employ peptide amphiphiles (PAs) which are lipidated peptides capable of self-assembling into micelles in water that can enhance cellular association. With this approach in mind, a series of triblock VIP amphiphiles (VIPAs) has been synthesized to explore the influence of block arrangement and hydrophobicity on micelle biocompatibility and bioactivity. VIPA formulation has been found to influence the shape, size, and surface charge of VIPA micelles (VIPAMs) as well as their cytotoxicity and immunomodulatory effects. Specifically, the enclosed work provides strong evidence that cylindrical VIPAMs with aspect ratios of 1.5-150 and moderate positive surface charge are able to potentiate the bioactivity of VIP limiting TNF-α secretion and MHC II and CD86 surface expression on APCs. With these criteria, we have identified PalmK-(EK)4-VIP as our lead formulation, which showed comparable or enhanced anti-inflammatory effects relative to the unmodified VIP at all dosages evaluated. Additionally, the relationships between peptide block location and lipid block size provide further information on the chemical structure-function relationships of PA micelles for the delivery of VIP as well as potentially for other peptides more broadly.

Anomalous Phase Behaviors of Monolayer NaCl Aqueous Solutions Induced by Effective Coulombic Interactions within Angstrom-Scale Slits.

Interests in subnanofluidic devices have called for molecular dynamics (MD) simulation studies of the thermodynamic behavior of monolayer salt solution within angstrom-scale slits. However, it still remains a grand challenge to accurately describe the Coulombic interactions by incorporating the effects of charge transfer and electronic dielectric screening. Herein, by using the electronic continuum model, where the effective ion charges are fine-tuned with a scaling factor of λ, we present simulation evidence that the effective Coulombic interactions among Na+/Cl- ions can strongly affect the behavior of monolayer ionic aqueous solution. Our microsecond-scale MD simulations show that only the counterions with moderate effective charges (0.3 ≤ λ ≤ 0.8) can dissolve in monolayer water, whereas the high effective charges (λ ≥ 0.85) induce ions to assemble into monolayer nanocrystals, and ions with the low effective charges (λ ≤ 0.2) exhibit gas-like nanobubble. These findings could provide deeper insights into the physical chemistry behind subnanofluidic iontronic devices.

Highly sensitive and selective room-temperature gas sensors based on B6N6H6 monolayer for sensing SO2 and NH3: A first-principles study

We applied first-principles calculations and studied the structures and electronic properties of SO2, NH3, H2, N2, CH4, H2O, N2O, CO, CO2, HCN, and H2S molecules adsorbed on the B6N6H6 monolayer to understand its performance as a sensor. The crystalline structure of the B6N6H6 monolayer remains thermodynamic stable under T = 1000 K, and the rippled structure is more stable than the planar one. The NH3 and SO2 molecules are chemically and physically, respectively, adsorbed on the B6N6H6 monolayer with moderate adsorption energy and charge transfer. By adsorbing NH3 and SO2, B6N6H6 monolayer electronic properties (especially conductivity) could be adjusted. Adsorption of other molecules did not have any similar effects. The recovery times of NH3 and SO2 desorption from the monolayer were only 0.42 ms and 1.1 s, respectively, at room temperature. The existence of humidity would have, to a certain extent, influence on the sensing of SO2 or NH3 gas using B6N6H6 monolayer. It is thus predicted that the B6N6H6 monolayer could be a room-temperature NH3 and SO2 sensor in a dry environment with high selectivity and sensitivity and fast response and recovery time. We also believe that the B6N6H6 monolayer will be a good candidate for NH3 work-function-type gas sensors.

Ionic Transport Triggered by Asymmetric Illumination on 2D Nano-Membrane.

Ionic transport and ion sieving are important in the field of separation science and engineering. Based on the rapid development of nanomaterials and nano-devices, more and more phenomena occur on the nanoscale devices in the field of thermology, optics, mechanics, etc. Recently, we experimentally observed a novel ion transport phenomenon in nanostructured graphene oxide membrane (GOM) under asymmetric illumination. We first build a light-induced carriers’ diffusion model based on our previous experimental results. This model can reveal the light-induced ion transport mechanism and predict the carriers’ diffusion behavior under different operational situations and material characters. The voltage difference increases with the rise of illuminate asymmetry, photoresponsivity, recombination coefficient, and carriers’ diffusion coefficient ratio. Finally, we discuss the ion transport behavior with different surface charge densities using MD simulation. Moderate surface charge decreases the ion transport with the same type of charge due to the electrostatic repulsion; however, excess surface charge blocks both cation and anion because a thicker electrical double layer decreases effective channel height. Research here provides referenced operational and material conditions to obtain a greater voltage difference between the membrane sides. Also, the mechanism of ion transport and ion sieving can guide us to modify membrane material according to different aims.

Hexagonal MBene (Hf2BO2): A Promising Platform for the Electrocatalysis of Hydrogen Evolution Reaction.

Hexagonal MAB (h-MAB) phases and their two-dimensional (2-D) derivatives (h-MBenes) have emerged as promising materials since the discovery of Ti2InB2. Herein, we identified that a possible h-MBene, 2-D Hf2BO2, can be an excellent platform for the electrocatalysis of hydrogen evolution reaction (HER) by density functional theory calculations. We proposed two approaches of transition metal (TM) modifications by atom deposition and implanting to optimize the HER performance of 2-D Hf2BO2. It is revealed that a moderate charge reduction of surface O, which is induced by the introduction of TM atoms, is conductive to a higher catalytic performance. The synergistic effect between implanted TM atoms and Hf2BO2 matrix can efficiently activate the surface by broadening O-p orbitals and shifting up p-band center, especially for V, Cr, and Mo as dopants, which can reduce the Gibbs free energy (ΔGH*) from 0.939 to -0.04, 0.05 and -0.04 eV, respectively. Interestingly, this effect works within a local region and the activity can also be evaluated by bond length of Hf-O, in addition to ΔGH*. This work suggests that due to its excellent electrocatalysis properties, h-MBenes can open up a new area for 2-D materials and will stimulate researchers to explore the synthesis of h-MAB phases and the stripping of h-MBenes.

Atomic configurations and energies of Mg symmetric tilt grain boundaries: ab initio local analysis

Mg alloys are highly expected for the wide application in the next-generation industry, while significant improvement of the plasticity of polycrystalline Mg alloys is crucial. For this purpose, it is essential to get insights into the atomic configurations, energetics, and mechanical responses of Mg grain boundaries (GBs). In this study, we investigated the overall features of atomic configurations and energies of and symmetric tilt GBs in hcp Mg by density-functional theory. We systematically constructed atomic models of coincidence-site lattice GBs by the arrangement of structural units in the full range of rotation angles. We observed that special GBs show clear cusps in both the GB-energy and excess-volume curves against the rotation angle. The reason of the stability/instability of each GB configuration was analyzed by ab initio local energy and local stress based on Bader partitioning. The features of local energies and stresses in Mg GBs are quite different from those in other materials with covalent or partial-covalent bonding nature. We observed substantial variations of local energies, local stresses and Bader charges of GB atoms, and charge inhomogeneity in a GB region, reflecting the structural disorder. Stable GBs are characterized by modest ranges of such variations and by moderate charge homogeneity. These results could be utilized in general to understand the interface stability and deformation mechanism of Mg and other simple metals.

Structural Evolution and Transition Dynamics in Lithium Ion Battery under Fast Charging: An Operando Neutron Diffraction Investigation.

Fast charging (<15 min) of lithium‐ion batteries (LIBs) for electrical vehicles (EVs) is widely seen as the key factor that will greatly stimulate the EV markets, and its realization is mainly hindered by the sluggish diffusion of Li+. To have a mechanistic understanding of Li+ diffusion within LIBs, in this study, structural evolutions of electrodes for a Ni‐rich LiNi0.6Mn0.2Co0.2O2 (NMC622) || graphite cylindrical cell with high areal loading (2.78 mAh cm−2) are developed for operando neutron powder diffraction study at different charging rates. Via sequential Rietveld refinements, changes in structures of NMC622 and Li x C6 are obtained during moderate and fast charging (from 0.27 C to 4.4 C). NMC622 exhibits the same structural evolution regardless of C‐rates. For phase transitions of Li x C6, the stage I (LiC6) phase emerges earlier during the stepwise intercalation at a lower state of charge when charging rate is increased. It is also found that the stage II (LiC12) → stage I (LiC6) transition is the rate‐limiting step during fast charging. The LiC12 → LiC6 transition mechanism is further analyzed using the Johnson–Mehl–Avrami–Kolmogorov model. It is concluded as a diffusion‐controlled, 1D phase transition with decreasing nucleation kinetics under increasing chargingrates.

Theoretical studies about C2H2 semi-hydrogenation on the carbon material supported metal cluster catalysts: Influences of support type and cluster size on the catalytic performance

The support type and cluster size of the supported catalysts strongly affect their catalytic performance toward the targeted reaction. This study is designed to investigate the influences of support type and cluster size on C2H4 selectivity and activity of C2H2 semi-hydrogenation; density functional theory calculations were utilized to illustrate C2H2 semi-hydrogenation mechanism on the catalysts with the different carbon material supported different sizes of metal clusters. The results show that for the different carbon material supported single-atom Cu or Pd catalysts, the support types greatly affect C2H4 selectivity and activity, among them, GDY support shows excellent catalytic performance. On the other side, as to the Mn/GDY (M=Cu, Pd) catalysts with different cluster sizes, the activity of Pdn/GDY is generally better than that of Cun/GDY; while the selectivity of Cun/GDY is better than that of Pdn/GDY. Interestingly, Pd1/GDY presents excellent C2H4 selectivity and activity for C2H2 semi-hydrogenation, attributing to its moderate Mulliken charge of metal atoms. This study could provide valuable structure clue for the obtaining of highly-efficient supported catalysts with suitable carbon material support and cluster size.

Effective pseudocapacitive performance of binder free transparent α-V2O5 thin film electrode: Electrochemical and some surface probing

Vanadium oxide nanomaterial was successfully prepared on conductive substrate via a simple and facile chemical route with no binder or additive. The film was characterized to investigate its microstructural, optical, electrical and electrochemical properties. The SEM micrographs of the annealed film presented enabling environment that is required for effective photocatalysis. It also demonstrated enhanced interaction between the film and the substrate and adequate pore size distribution that can allow free electrolytic ion intercalation/deintercalation for efficient supercapacitive response. EDX confirmed the elemental composition of the film. XRD and Raman spectroscopy showed substantial characteristic peaks that are attributes of orthorhombic crystal structure of V2O5 powder. Optical studies showed that the film exhibited high visible light transmittance and its energy band gap was found to be 2.77 eV. Pseudocapacitive performance of the V2O5 electrode was investigated via a three-electrode cell configuration. The film electrode exhibited highest areal capacity of 1.18 μAh cm−2, energy density of 0.485 μWhcm−2 at a power density of 107.71 μWcm−2 and current density 0.25 mAcm−2, moderate charge transfer resistance and superior cycling stability. The study demonstrated the viability of V2O5 film as electrode material for the development of high-performance supercapacitors.

Honeycomb-inspired design of a thermal management module and its mitigation effect on thermal runaway propagation

The mitigation of battery thermal runaway propagation remains challenging in the application of lithium-ion batteries, and safety enhancement remains a popular topic for battery thermal management. In this study, an aluminum honeycomb (AH) design module is proposed for a battery thermal management module, and its effects on thermal management (TM) and thermal runaway (TR) propagation are experimentally studied using an infrared imager. The results showed that AH contributed to an improved heat dissipation effect and thus mitigated thermal runaway propagation. In addition, the coupling effects of AH as well as forced convection and the phase change material (PCM) were investigated. The results indicated that the coupling effects of the AH and forced air along with the PCM both exhibited superior performance as compared to the AH alone. In a forced convection environment, the maximum temperature of the AH cell could be reduced by 17.1% under a moderate charging rate. In addition, under extreme conditions, AH was shown to mitigate TR propagation. We anticipate that the outcomes of this study can provide a new basis for the structural design of battery modules to achieve better performance and fire safety.

Support-Induced unusual size dependence of Pd catalysts in chemoselective hydrogenation of para-chloronitrobenzene

For supported metal catalysts, the underlying support not only disperses and stabilizes metal particles, but also modulates their electronic structures remarkably, and even directly participates in catalytic reactions. Here we report that Pd nanoparticles (NPs) supported on oxygen-functionalized carbon black (Pd/O-C) show an unexpected inverse trend of selectivity on Pd particle size in chemoselective hydrogenation of para-chloronitrobenzene (p-CNB), compared to those on carbon black (Pd/C). In situ X-ray photoemission spectroscopy reveals that the Pd NPs are more positively charged with decrease of particle size in both samples, while the Pd NPs in Pd/O-C have relatively higher fractions of positive Pdδ+ species than those in Pd/C with similar sizes. Fourier transform infrared spectroscopy shows that the balance of positive Pdδ+ species strongly modulates the competitive adsorption of -NO2 and -Cl group in p-CNB according to their different electronegativities. As a consequence, we, for the first time, demonstrate that a moderate positive charge of Pd NPs is essential to improve the p-chloroaniline (p-CAN) selectivity, while too high or too low positive charge could impel the adsorption of the less negatively charged -Cl group, thus generating the dehalogenated aniline by-product. These findings suggest that precise tailoring of the electronic structures of metal NPs could be essential for design of high chemoselective metal catalysts.

Modulation of red organic room-temperature phosphorescence in heavy atom-free phosphors

Red room temperature phosphorescence (RTP) was conventionally obtained by incorporating heavy metal ions or halogens. However, heavy metals are toxic and expensive while C-halogen bonds are usually prone to photobleaching. Meanwhile, heavy atoms often lead to much reduced RTP lifetimes, precluding their use in certain fields. Herein, a series of naphthalene diimides with various electron-donor substituents on the nitrogen atoms were used to achieve red RTP. It was found that a moderate intramolecular charge transfer (CT) state provides mediating intersystem crossing channels for promoting red RTP with quantum yields circa. 5%. However, much stronger donors can in fact inhibit all forms of luminescence emission including RTP via photo-induced electron transfer quenching at room temperature, in which case the red phosphorescence could be restored if the donor, such as an amine, is suppressed by protonation.

One-step electrodeposition of CuSCN/CuI nanocomposite and its hole transport-ability in inverted planar perovskite solar cells

The synthesis of CuSCN/CuI nanocomposite by single-step electrodeposition is developed. The surface morphology and film thickness are controlled by changing the electrochemical potential and deposition time. The mixed-phase formation of CuSCN/CuI is confirmed through x-ray diffraction and Raman spectral analysis. Nanopetal (NP) like morphology of CuSCN/CuI is observed in FESEM micrographs. Interestingly, the NPs density and thickness are increased with increasing the deposition potential and time. The device fabricated using CuSCN/CuI nanocomposite as a hole transport layer (HTL) which is grown for 2 min delivers the best photovoltaic performance. The maximum power conversion efficiency of 18.82% is observed for CuSCN/CuI NP with a density of 1153 μm−2 and thickness of 142 nm. The charge transfer ability of the CuSCN/CuI NP HTL is analyzed by electrochemical impedance spectroscopy. Based on the observation, moderate charge transport resistance and optimum film thickness are required for achieving maximum photovoltaic performance in perovskite solar cells (PVSCs). Thus, the developed CuSCN/CuI NP HTL is a potential candidate for PVSCs.

Sustainable Intelligent Prediction and Price Recommendation System

Online brief time frame period condominium stages, comprising of Airbnb, had been transforming into mainstream, and a higher evaluating technique is indispensable for hosts of most recent postings. In this paper, the association is broken down among the portrayal of each rundown and its charge, and proposed a content essentially based absolutely charge counsel gadget alluded to as TAPE to suggest a moderate charge for recently brought postings. The deep knowledge utilized makes them more familiar with strategies (for example, feed-forward networks, longer short-term memory, and recommended moves) to design and put in an influential TAPE. By using a data set of 4 indistinguishable urban areas that were deleted sequentially, it was found that basic elements (such as small indoor objects and high-thickness areas) would undoubtedly have an adverse effect on the charges of each property, and evaluated that it is basic and more attractive style of. Our style is completed with 33.73 in Boston, 20.50 in London, 34.68 in Los Angeles and 26.31 in New York. This is related to the use of other current forms of highlighting.

Zinc Oxide Defect Microstructure and Surface Chemistry Derived from Oxidation of Metallic Zinc: Thin-Film Transistor and Sensor Behavior of ZnO Films and Rods.

Zinc oxide thin films are fabricated by controlled oxidation of sputtered zinc metal films on a hotplate in air at temperatures between 250 and 450 °C. The nanocrystalline films possess high relative densities and show preferential growth in (100) orientation. Integration in thin‐film transistors reveals moderate charge carrier mobilities as high as 0.2 cm2 V−1s−1. The semiconducting properties depend on the calcination temperature, whereby the best performance is achieved at 450 °C. The defect structure of the thin ZnO film can be tracked by Doppler‐broadening positron annihilation spectroscopy as well as positron lifetime studies. Comparably long positron lifetimes suggest interaction of zinc vacancies (VZn) with one or more oxygen vacancies (VO) in larger structural entities. Such VO‐VZn defect clusters act as shallow acceptors, and thus, reduce the overall electron conductivity of the film. The concentration of these defect clusters decreases at higher calcination temperatures as indicated by changes in the S and W parameters. Such zinc oxide films obtained by conversion of metallic zinc can also be used as seed layers for solution deposition of zinc oxide nanowires employing a mild microwave‐assisted process. The functionality of the obtained nanowire arrays is tested in a UV sensor device. The best results with respect to sensor sensitivity are achieved with thinner seed layers for device construction.

β-In2S3 as Water Splitting Photoanodes: Promise and Challenges

As the interest in sustainable energy production increases, water splitting through semiconductor materials to convert solar energy directly to hydrogen energy has been extensively reported to date. Recently, the III–VI group chalcogenide semiconductors have received great attention for narrow-gap photoelectrochemical (PEC) water splitting electrodes. Among the metal sulfides, beta indium sulfide (β-In2S3) shows remarkable properties for photoelectrodes such as high photoelectric sensitivity, high photoconductivity, large photoelectric conversion yield, low toxicity, high absorption coefficient, efficient charge separation, moderate charge transport, appropriate band position, and narrow band gap. Most of its unique properties come from the defective spinel crystal structure. Despite the superior advantages, there is a serious problem of photocorrosion induced by accumulated holes on the surface of the electrodes during the photocatalytic reaction under illumination which reduces the PEC properties. Herein, we review overall physicochemical and optoelectronic properties of β-In2S3, regardless of pros and cons, followed by the discussion of assorted strategies to further improve the PEC activities.

Effect of ALD window on thermal ALD deposited HfOx/Si interface for silicon surface passivation

The quality of oxide-silicon interface plays a crucial role in reducing the surface recombination losses. In the present study, we demonstrate the importance of ALD temperature window and its impact on the quality of HfOx/Si interface using X-ray photoelectron spectroscopy (XPS), Variable angle spectroscopy ellipsometry (VASE) and Capacitance-voltage (C-V) measurements. VASE results confirm that for films grown within the ALD window the film growth is uniform across the wafer. XPS results show that performing a post deposition anneal restructures the interfacial layer and oxidizes the interface. C-V results conclude that positive fixed charges are present in the pristine films, however negative charges are activated after performing post deposition annealing. Further, it is observed that to investigate the true properties of the deposited layer, the films should be annealed before metallization. It is thus concluded that uniform films would be grown for films deposited at temperature lying within the ALD window and would effectively passivate silicon surface owing to their low interface defect density and moderate fixed oxide charges.

Assessment of the Wolf method using the Stillinger-Lovett sum rules: From strong electrolytes to weakly charged colloidal dispersions.

The Ewald method has been the cornerstone in molecular simulations for modeling electrostatic interactions of charge-stabilized many-body systems. In the late 1990s, Wolf and collaborators developed an alternative route to describe the long-range nature of electrostatic interactions; from a computational perspective, this method provides a more efficient and straightforward way to implement long-range electrostatic interactions than the Ewald method. Despite these advantages, the validity of the Wolf potential to account for the electrostatic contribution in charged fluids remains controversial. To alleviate this situation, in this contribution, we implement the Wolf summation method to both electrolyte solutions and charged colloids with moderate size and charge asymmetries in order to assess the accuracy and validity of the method. To this end, we verify that the proper selection of parameters within the Wolf method leads to results that are in good agreement with those obtained through the standard Ewald method and the theory of integral equations of simple liquids within the so-called hypernetted chain approximation. Furthermore, we show that the results obtained with the original Wolf method do satisfy the moment conditions described by the Stillinger-Lovett sum rules, which are directly related to the local electroneutrality condition and the electrostatic screening in the Debye-Hückel regime. Hence, the fact that the solution provided by the Wolf method satisfies the first and second moments of Stillinger-Lovett proves, for the first time, the reliability of the method to correctly incorporate the electrostatic contribution in charge-stabilized fluids. This makes the Wolf method a powerful alternative compared to more demanding computational approaches.

Robust Inorganic Hole Transport Materials for Organic and Perovskite Solar Cells: Insights into Materials Electronic Properties and Device Performance

Interfaces in perovskite and organic solar cells play a central role in advancing efficiency and prolong device durability. They improve charge transport/transfer from the absorber layer to the collecting electrodes, while also blocking the opposite charge carriers, minimize voltage losses by suppressing charge recombination. and may act as buffer/protective layers and nanomorphology regulators for the absorber layer. One such interface is formed by the hole transport layer (HTL) and the organic/perovskite absorber. These HTLs typically consist of organic semiconductors, which, although are solution processable at low temperatures and allow perfect energy‐level alignment with the absorber layer and therefore efficient charge collection, are prone to degradation in ambient conditions and under continuous light exposure. In a quest for robust alternatives, inorganic materials such as metal oxides, graphene oxide, bronzes, copper thiocyanate, and transition metal dichalcogenides are actively investigated. However, their hole extraction capability is inferior compared with organic semiconductors as they possess specific energetics leading to significant charge extraction barriers and moderate charge collection. To achieve further advancements in their hole transporting capabilities, strongly interconnecting knowledge of their synthesis, electronic properties, and device performance metrics is required.

Adsorption of cyanogen halides (X-CN; X = F, Cl and Br) on pristine and Fe, Mn doped C60: A highly potential gas sensor

Reliable monitoring of toxic and pollutant gases is a prime concern of the technological and scientific communities, simulated by the terrible environmental pollution crisis. Herein, we systematically investigated the gas (X-CN; X = F, Cl, Br) sensing mechanism of pristine, transition metal (Fe and Mn) doped fullerene C60 using first-principles calculations. The pure C60 surface show quite weak adsorption behavior towards X-CN gas molecules that gives rise to physisorption in these complexes, while chemisorption is observed for the Fe, Mn doped C60/X-CN configurations. Moreover, the prominent adsorption strength, moderate charge transfer and appreciable electronic conductivity demonstrates high sensitivity of metal doped C60 cage towards cyanogen halide gas molecules. The simulated electronic band structure and optical absorption spectra using HSE06 hybrid functional show strong variations after the adsorption of X-CN gases, revealing the potential capability of metal doped C60 as reliable gas sensor. Especially, the band gaps of Fe, Mn doped C60/X-CN complexes were reduced from that of pure counterpart, representing a strong signal for the detection of cyanogen halide gases. Further, the sensitivity of X-CN gases were correlated with π electron occupancy of the host materials. As we extol the remarkable sensitivity of fullerene C60, we believe that these findings may capture widespread attention towards wearable chemical sensors for future applications.