Increase In Surface Potential Research Articles

Breath moisture-induced electroactive nanofibrous membrane for efficient antibacterial and antiviral air filtration

The high humidity environment created by human breath can easily lead to charge loss in the mask's filter and weaken the mask's filtration effect on aerosols containing bacteria and viruses. Therefore, in this study, a breath moisture-induced electroactive nanofibrous membrane was prepared by incorporating Cu/Zn nanoparticles into cellulose acetate/poly (vinyl butyral) fibers. Adjacent Cu/Zn nanoparticles can form galvanic couples that can be activated by human breath to undergo redox discharge reactions, thus imparting moisture-induced electroactivity to nanofibrous membrane. Based on the moisture-induced electroactivity, nanofibrous membrane demonstrated antibacterial rates of 98.32 % against Escherichia coli (E. coli) and 99.06 % against Staphylococcus aureus (S. aureus). Moreover, moisture-induced electroactive nanofibrous membrane significantly reduced the titer of Enterovirus 71 (EV71) transmitted through the respiratory tract within 5 min. The excellent antibacterial and antiviral performance of electroactive nanofibrous membrane can be attributed to the synergistic effect of Cu/Zn’s electrical stimulation (ES) interference on the electrodynamics of bacteria and viruses, the generated reactive oxygen species (ROS), and the released metal ions. Benefiting from the increased surface potential from Cu/Zn galvanic couples, moisture-induced electroactive nanofibrous membrane exhibited a filtration efficiency of 99.61 % for PM0.3 particles while maintaining a low-pressure drop (78 Pa). Meanwhile, electroactive nanofibrous membrane showed excellent wear comfort and non-cytotoxicity. In summary, this moisture-induced electroactive nanofibrous membrane maintains high filtration performance and exhibits excellent antibacterial and antiviral activities, shedding some light on developing novel efficient air filters.

Localized corrosion characteristics of Al-Mg-Si aluminum alloy with aging time and pre-delayed aging condition

The effects of single aging, delayed aging and pre-delayed aging treatment on the corrosion resistance of Al-Mg-Si alloy were studied by scanning Kelvin probe force microscopy (SKPFM), transmission electron microscopy (TEM), scanning electron microscopy (SEM), three-dimensional X-ray tomography (3D-XRT), confocal laser scanning microscopy (CLSM) and electrochemical measurements. The surface potentials of Al(MnFe)Si, Mg2Si, and Si-rich remnant phases are determined, identifying Al(MnFe)Si phase as the crucial cathodic site for corrosion initiation, and the increase in surface potential implies an accelerated corrosion rate after immersion. The intergranular corrosion susceptibility of the alloy is predominantly influenced by the microstructure caused by aging conditions. The factors affecting corrosion resistance are summarized as (i) adjustment of electrochemical reaction activity by controlling the area fraction of Al(MnFe)Si phase, (ii) the spacing of grain boundary precipitates (GBPs), and (iii) the width of the precipitation-free zone (PFZ). The delayed aging (DA) sample exhibits inferior corrosion resistance due to the continuous GBPs and extended sub-grain boundaries corrosion propagation paths. The pre-delayed aging treatment successfully mitigates the corrosion degree of DA by widening the GBPs spacing and narrowing the PFZ width. This suggests that pre-aging treatment is a potent strategy for enhancing corrosion resistance without compromising the alloy's strength.

Intrinsic surface states with electron–surface optical phonon interaction influence in wurtzite Zn-IV-N2 semiconductors

The electronic intrinsic surface states in wurtzite Zn-IV-N2 (with group-[Formula: see text], Ge and Si) semiconductors were investigated using an intermediate-coupling variational approach considering the electron–surface optical phonon interaction influence. The intrinsic surface state energy distribution and the average penetrating depth of surface state eigen-wave function of the electron have been evaluated numerically by changing the surface potential barrier [Formula: see text] for wurtzite ZnSnN2, ZnGeN2 and ZnSiN2, respectively. The results show that the electronic intrinsic surface state energy increased linearly with increasing surface potential barrier [Formula: see text] for all the calculated materials. The result also indicated that the electronic intrinsic surface state energies variations due to the influence of electron–surface optical phonon interaction are dozens of[Formula: see text]meV. The average penetrating depth of electronic surface state eigen-wave function is independent of [Formula: see text]. Its value is no more than the corresponding material’s lattice constant. The electronic scattering by surface optical phonon should be taken into account in the study of the intrinsic surface state of electrons in the group of Zn-IV-nitrides (with [Formula: see text], Ge and Si) semiconductors, especially for materials having strong electron–phonon interaction and wide band gap.

Highly positive fluorophlogopite for enhanced power generation in triboelectric nanogenerators prepared on a flexible Ni–Cu fabric

Recent developments in triboelectric nanogenerators (TENGs) facilitate creation of sustainable, self-powered energy harvesting systems. In our study, we introduce fluorophlogopite as a positive triboelectric material with excellent electron transfer capabilities. We investigate the efficacy of a fluorophlogopite-based TENG, MgF-mica-TENG. We use a simple spray method on flexible Ni–Cu conductive fabric platforms to perform electrical analyses including open-circuit voltage (Voc), short circuit current (Isc), and peak power density using a home-made, 3D-printed, M-shaped spring setup. MgF-mica-TENG exhibited enhanced performance compared to the conventional muscovite-based TENG (Al-mica-TENG). This enhanced performance is primarily attributed to the increased surface potential of fluorophlogopite, which facilitate efficient charge transfer upon the contact of two electrodes, combined with optimized 11fabrication parameters. Based on our findings, we anticipate that MgF-mica materials can pave the way to the development of a comprehensive strategy to powering smart electronics, harnessing the abundant mechanical energy sources found in our daily surroundings.

Application of a genetically engineered macrophage cell line for evaluating cellular effects of UV/US-treated poly(ethylene terephthalate) microplastics

Microplastic (MP) pollution is a global environmental problem. To understand the biological effects of MPs on humans, it is essential to evaluate the response of human cells to model plastic particles that mimic environmental MPs in a sensitive and non-invasive manner. In this study, we investigated the preparation of poly(ethylene terephthalate) (PET) fragments with properties similar to those of environmental MPs by combining photo-oxidative degradation via ultraviolet (UV) irradiation with mechanical pulverization and hydrolysis via ultrasound (US) exposure. Combination of UV and US treatments decreased the particle size of PET fragments to 10.2 µm and increased their crystallinity and Young's modulus to 35.7 % and 0.73 GPa, respectively, while untreated PET fragments showed the particle size of 18.9 µm, the crystallinity of 33.7 %, and Young’s modulus of 0.48 GPa. In addition, an increase in negative surface potential and O/C ratio were observed for UV/US-treated PET fragments, suggesting surface oxidation via UV/US treatment. Cytokine secretion from human macrophages was evaluated by a highly sensitive inflammation evaluation system using the HiBiT-based chemiluminescence detection method developed by genome editing technology. UV/US-treated PET fragments induced a 1.4 times higher level of inflammatory cytokine secretion on inflammatory macrophages than untreated ones, suggesting that the biological responses of PET fragments could be influenced by changes in material properties via oxidation. In conclusion, UV/US treatment enables efficient preparation of model plastic particles and is expected to provide new insights into the evaluation of biological effects using human cells. (240 words)

Enhanced foamability and stability of aqueous foams through novel pickering fat globules formulated with solid lipid particles

Pickering fat globules (PFGs), known for their remarkable stability via the Pickering effect, eco-friendliness, and ability to carry hydrophobic flavors and nutrients, play a pivotal role in the advancement of food foam systems. This study investigates highly unsaturated and exceptionally stable aqueous foams stabilized by PFGs with interfacial activity. These PFGs are derived from two types of solid lipid particles (SLPs): fully hydrogenated soybean oil with sodium caseinate (FHSO-SC-SLPs-PFGs) and glyceryl stearate citrate (GSC-SLPs-PFGs), which were formulated with varying SLPs concentrations (0.5 wt%, 2.5 wt% and 5 wt%) while coating 10 wt% and 20 wt% oil droplets. Remarkably, 0.5 wt% SLPs could accommodate up to 20 wt% of low-melting-point liquid oil, enhancing the unsaturation of PFGs. GSC-SLPs-PFGs generated foams with overrun values reaching up to 235%, exhibiting stability for at least 40 days. In contrast, foams derived from FHSO-SC-SLPs-PFGs, with the highest overrun value of 145%, remained stable for only 2 h. Compared with FHSO-SC-SLPs-PFGs, GSC-SLPs-PFGs exhibited superior foaming performance and stability attributed to their properties such as smaller particle size, enhanced hydrophilicity, higher apparent viscosity, increased surface potential, and superior surface tension reduction. Furthermore, increasing the concentration of SLPs and/or reducing the oil phase can also improve the properties of SLPs-PFGs, resulting in greater foamability and foam stability. Surface dynamic adsorption, interfacial shear rheology, and microstructural observations revealed robust adsorption of all SLPs-PFGs at the air-liquid interface, indicative of pronounced Pickering stabilization, with GSC-SLPs-PFGs also exhibited three-dimensional network structure. These SLPs-PFGs stabilized foams presented heightened stability and reduced saturated fat content, paving the way for novel and healthier foam-based food products.

Femtosecond laser-induced crystallization in Er/Yb:BaTiO3 perovskite films: Effects on the optical and electrical properties

Femtosecond laser-induced crystallization in Er3+/Yb3+:BaTiO3 (BTEY) perovskite films has sparked significant research interest in materials science and photonics, driven by the need for innovative techniques to control material properties and exploit their potential. Our study delves into this burgeoning area by demonstrating the controlled crystallization of amorphous BTEY thin films under femtosecond laser (fs-laser) irradiation at 1030 nm. The threshold fluence to achieve laser processing was determined as approximately 1.1 J/cm2 at 1 kHz, as well as the irradiation conditions for crystallization (pulse energy, repetition rate, and scanning speed), whose background mechanism is discussed. Our Raman spectroscopy analysis confirmed crystallization when irradiation was carried out at 1 kHz repetition rate, while no evidence of the crystalline phase of BTEY emerged at 1 MHz irradiation. Moreover, our results reveal a remarkable increase in luminescence enhancement and surface potential (∼65 mV) in the film. These outcomes represent a significant breakthrough with relevant implications for advanced photonic devices like modulators and detectors. By harnessing fs-laser pulses for BTEY crystallization, our findings offer new avenues for practical device applications.

Biodegradation of Oxide Nanoparticles in Apoferritin Protein Media: A Systematic Electrochemical Approach

AbstractFunctional oxide nanoparticles are extensively utilized in the last decades for biomedical purposes due to their unique functional properties. Nevertheless, their biodegradation mechanism by biological species, particularly by proteins at oxide/protein interfaces, still remains limited. Here, a systematic approaches is provided to investigate electrochemical behavior, electronic properties, and biodegradation mechanism of cobalt ferrite (CFO) and cobalt ferrite‐bismuth ferrite (CFO‐BFO) core‐shell nanoparticles in apoferritin‐containing media. Scanning Kelvin probe force microscopy results indicate that the presence of a thin shell (≈5 nm) of BFO on CFO causes a significant increase in surface potential. The potentiodynamic polarization measurements in different solutions showed higher anodic current densities for both samples when decreasing pH and increasing apoferritin concentration. Notably, CFO‐BFO exhibits lower anodic current densities than CFO due to a slightly higher flat band potential and lower donor density distribution on CFO‐BFO than on CFO, which results in lower electrochemical activity. Long‐term monitoring reveals that biodegradation of both nanoparticles is accelerated by high apoferritin concentrations and acidic media, resulting in the decrease of electrochemical potentials and impedance values, and enhancement of metal ion release. Thus, this systematic biodegradation study can help to predict the lifespan and toxicity of these functional nanoparticles in biological environments.

Use of Various UVC Photofunctionalization Times to Modify Surface Characteristics and Enhance the Biologic Activity of SLA Titanium.

To evaluate the effect of ultraviolet-C light (UVC) photofunctionalization treatment time on the biologic activity of airborne particle-abraded and acid-etched (SLA) titanium surfaces and to analyze its physical and chemical mechanisms. SLA titanium was treated with UVC light for different lengths of time (10 minutes, 20 minutes, 30 minutes, 1 hour, 2 hours, 4 hours, and 24 hours), and then changes to its surface characteristics were evaluated via electron microscope scanning, X-ray photoelectron spectroscopy (XPS), water contact angle measurement, and zeta potential measurement. The effect of UVC photofunctionalization on the biologic processes of SLA titanium surfaces was assessed by analyzing the bovine serum albumin adsorption, adhesion, proliferation, morphology, and alkaline phosphatase activity of MG-63 cells. UVC irradiation did not change the topography of SLA titanium surfaces. As treatment times increased, the water contact angle decreased from 120 degrees to 0 degrees, and the hydrocarbon content decreased. Zeta potential testing showed increased surface potential of photofunctionalized titanium. In vitro testing showed that cell adhesion, proliferation, morphology, and alkaline phosphate (ALP) activity on titanium surfaces were significantly improved by UVC photofunctionalization. UVC photofunctionalization can improve the biologic activity of SLA titanium surfaces by removing hydrocarbons and increasing the surface potential of titanium.

Reexamining the Role of Solution-Cast Ferroelectric Polymer Interlayer toward Enhanced Efficiency and Stability in Conventional Organic Solar Cells.

Interfacial modification is crucial for achieving efficient and stable organic solar cells (OSCs). Herein, an N,N-dimethylformamide (DMF) solution-cast poly(vinylidene fluoride-co-trifluoroethylene) (P(VDF-TrFE)) interlayer was applied to enhance the efficiency and stability of a range of OSCs, and the underlying mechanism was revealed via morphological and device physics studies. DMF rinse during the P(VDF-TrFE) interlayer casting process strengthens π-π stacking of the active layer with fibril aggregation, optimized phase separation, and vertical component distribution, while the P(VDF-TrFE) interlayer with rich diploes contributes to increased surface potential and internal electric field. The synergistic effect of the P(VDF-TrFE) interlayer and DMF rinse increases the PCEs of PM6:IT-4F, PM6:C5-16, and PM6:L8-BO OSCs from 12.7, 17.9, and 18.2% to 13.1, 18.7, and 18.8%, respectively. Additionally, OSCs containing the P(VDF-TrFE) interlayer also showed improved storage stability.

Effect of Lactobacillus plantarum fermentation on the physicochemical properties and flavor of rice protein-carboxymethylcellulose complexes.

Fermentation is known to enhance the nutritional profile and confer unique flavors to products. However, the resultant effects on stability and physicochemical properties remain unexplored. This study aims to elucidate the influence of fermentation on the stability and organoleptic characteristics of a rice protein beverage stabilized by carboxymethyl cellulose (CMC). The findings revealed that the average aggregate size escalated from 507 to 870 nm, concurrently exhibiting a significant increase in surface potential. The aggregation enhancement was substantiated by evident morphological changes and confocal laser scanning microscopical (CLSM) observations. A negative correlation was discerned between the physical stability of the beverage and fermentation duration. Moreover, flavor analysis of the beverage post a 3 h fermentation period highlighted an increase in aromatic ester compounds, thereby intensifying the aroma. The study corroborates that fermentation can detrimentally influence product stability while concurrently improving its flavor profile. By establishing a mix ratio of 10:1 for rice protein and CMC and forming a relatively stable system through electrostatic interaction at a pH of 5.4, a flavorful rice protein beverage can be derived post 3 h-fermentation process. These findings offer insights into the impact of varying fermentation durations on the stability and flavor of polysaccharide-based rice protein beverages. © 2023 Society of Chemical Industry.

Design and Performance Analysis of Negative Capacitance Effect in the Charge Plasma-Based Junction-Less Vertical TFET Structure

In this paper, a negative capacitance (NC) effect in series with normal oxide capacitance is first time introduced to design negative capacitance charge plasma-based junction less vertical TFET structure (NC-CP-JL-VTFET). The introduced negative capacitance enhances the overall gate capacitance and hence gate capacitive coupling and thus renders high current capabilities with reduced sub-threshold slope and threshold voltage. With the use of negative capacitance along with oxide capacitance, it has been seen that the same drain current is achieved at lower gate voltage as compared to without use of negative capacitance and since the voltage scaling is done considerably, the dynamic power dissipation in circuit application can be reduced significantly. To generate the negative capacitance during the device operation; ferroelectric material [Formula: see text](VDF-TrFE) poly(vinylidene fluoride-trifluoro ethylene) is used in stack with SiO2 gate oxide. Various performance parameters of the designed structure such as electron–hole concentration in the tunneling junction, electric field, surface potential, electron–hole quasi-Fermi variation, and drain current variation are investigated and compared with the results of without considering the ferroelectric material in the gate oxide. The variation of the ferroelectric thickness on the device performance is also investigated. The investigation exhibits significant improvement in the drain current and in the other parameters as well. These improvements are seen because of higher capacitive coupling and these effects are further responsible for more energy band bending which in turn govern high electron tunneling. Due to the existence of negative capacitance, the peak value of the electric field gets doubled while the surface potential increases 44% from the normal structure.

Electroactive, Antibacterial, and Biodegradable Poly(lactic acid) Nanofibrous Air Filters for Healthcare.

Poly(lactic acid) (PLA)-based nanofibrous membranes (NFMs) hold great potential in the field of biodegradable filters for air purification but are largely limited by the relatively low electret properties and high susceptibility to bacteria. Herein, we disclosed a facile approach to the fabrication of electroactive and antibacterial PLA NFMs impregnated with a highly dielectric photocatalyst. In particular, the microwave-assisted doping (MAD) protocol was employed to yield Zn-doped titanium dioxide (Zn-TIO), featuring the well-defined anatase phase, a uniform size of ∼65 nm, and decreased band gap (3.0 eV). The incorporation of Zn-TIO (2, 6, and 10 wt %) into PLA gave rise to a significant refinement of the electrospun nanofibers, decreasing from the highest diameter of 581 nm for pure PLA to the lowest value of 264 nm. More importantly, dramatical improvements in the dielectric constants, surface potential, and electret properties were simultaneously achieved for the composite NFMs, as exemplified by a nearly 94% increase in surface potential for 3-day-aged PLA/Zn-TIO (90/10) compared with that of pure PLA. The well regulation of morphological features and promotion of electroactivity contributed to a distinct increase in the air filtration performance, as demonstrated by 98.7% filtration of PM0.3 with the highest quality factor of 0.032 Pa-1 at the airflow velocity of 32 L/min for PLA/Zn-TIO (94/6), largely surpassing pure PLA (89.4%, 0.011 Pa-1). Benefiting from the effective generation of reactive radicals and gradual release of Zn2+ by Zn-TIO, the electroactive PLA NFMs were ready to profoundly inactivate Escherichia coli and Staphylococcus epidermidis. The exceptional combination of remarkable electret properties and excellent antibacterial performance makes the PLA membrane filters promising for healthcare.

A Phenomenological Model for Electrical Transport Characteristics of MSM Contacts Based on GNS.

Graphene nanoscroll, because of attractive electronic, mechanical, thermoelectric and optoelectronics properties, is a suitable candidate for transistor and sensor applications. In this research, the electrical transport characteristics of high-performance field effect transistors based on graphene nanoscroll are studied in the framework of analytical modeling. To this end, the characterization of the proposed device is investigated by applying the analytical models of carrier concentration, quantum capacitance, surface potential, threshold voltage, subthreshold slope and drain induced barrier lowering. The analytical modeling starts with deriving carrier concentration and surface potential is modeled by adopting the model of quantum capacitance. The effects of quantum capacitance, oxide thickness, channel length, doping concentration, temperature and voltage are also taken into account in the proposed analytical models. To investigate the performance of the device, the current-voltage characteristics are also determined with respect to the carrier density and its kinetic energy. According to the obtained results, the surface potential value of front gate is higher than that of back side. It is noteworthy that channel length affects the position of minimum surface potential. The surface potential increases by increasing the drain-source voltage. The minimum potential increases as the value of quantum capacitance increases. Additionally, the minimum potential is symmetric for the symmetric structure (Vfg = Vbg). In addition, the threshold voltage increases by increasing the carrier concentration, temperature and oxide thickness. It is observable that the subthreshold slope gets closer to the ideal value of 60 mV/dec as the channel length increases. As oxide thickness increases the subthreshold slope also increases. For thinner gate oxide, the gate capacitance is larger while the gate has better control over the channel. The analytical results demonstrate a rational agreement with existing data in terms of trends and values.

Electrostatic charges and their distribution on the charged surfaces probed by sum-frequency generation spectroscopy

We examined the electrostatic charging states of insulating polymer surfaces using sum-frequency generation (SFG) spectroscopy. For the negatively charged polypropylene, the SFG peak amplitudes increased significantly with increasing surface potential, indicating that the electric-field formed by the electrostatic charges directly affects the SFG signal intensities. In the organic thin films stacked on top of PMMA, an increase in the SFG signal of buried PMMA is observed, indicating that the electrostatic field formed by the electrical charges is extended into the bulk direction. In addition, visualization of the location and distribution of the charges is demonstrated using the SFG intensity variations.

Possible handle for broadening the catalysis regime towards low temperatures: proof of concept and mechanistic studies with CO oxidation on surface modified Pd-TiO2.

The present work demonstrates the effect of temperature-dependent surface modification (SM) treatment and its influence in broadening the catalysis regime with Pd-TiO2 catalysts prepared by various methods. Due to SM induced changes, a shift in the onset of CO oxidation activity as well as broadening of the oxidation catalysis regime by 30 to 65 K to lower temperatures is observed compared to the temperature required for virgin counterparts. SM carried out at 523 K for PdPhoto-TiO2 exhibits the lowest onset (10% CO2 production - T10) and T100 for CO oxidation at 360 and 392 K, respectively, while its virgin counterpart shows T10 and T100 at 393 and 433 K, respectively. The SMd Pd-TiO2 catalysts were investigated using X-ray photoelectron spectroscopy (XPS), ultra-violet photoelectron spectroscopy (UPS) and atomic force microscopy (AFM). It is observed that diffusion of atomic oxygen into Pd-subsurfaces leads to SM and changes the nature of the surface significantly. These changes are demonstrated by work function (ϕ), surface potential, catalytic activity, and correlation among them. UPS results demonstrate the maximum increase in ϕ by 0.5 eV for PdPhoto-TiO2 after SM, compared to all other catalysts. XPS study shows a moderate to severe change in the oxidation states of Pd due to atomic oxygen diffusion into the subsurface layers of Pd. Kelvin probe force microscopy (KPFM) study also reveals corroborating evidence that the surface potential increases linearly with increasing temperature deployed for SM up to 523 K, followed by a marginal decrease at 573 K. The ϕ measured by KPFM and UPS shows a similar trend and correlates well with the changes in catalysis observed. Our results indicate that there is a strong correlation between surface physical and chemical properties, and ϕ changes could be considered as a global marker for chemical reactivity.

Effects of flexoelectric polarization on surface potential of dielectric thin-film heterostructures: A comparative study

Recently, flexoelectric effect has attracted considerable attention owing to ubiquitous existence in all dielectrics, regardless of the symmetry. It promises intriguingly physical phenomena, such as strain gradient-induced electric polarizations, photocurrents, and interfacial transports, as well as their electromechanical coupling with external force loading, in diverse materials for multifunctional applications in electronics. In this work, we report the flexoelectric-modulation on surface potential of LaFeO3 (LFO) thin-film heterostructures. The LFO thin film with or without the flexoelectric effect has been achieved by controlling epitaxial misfit against a substrate. Lattice structures and strain behaviors are observed by atomic-resolution high-angle annular dark-field imaging. Grown on a LaAlO3 substrate, a giant strain gradient of ∼3 × 106 m−1 is generated in the LFO thin film due to the gradual relaxation of large misfit strain with increasing thickness, yielding a robust flexoelectric polarization pointing to the heterostructure surface. In contrast, the LFO is almost fully strained on a SrTiO3 substrate due to the small lattice mismatch. The flexoelectric polarization results in an increase in surface potential in the LFO heterostructure due to the incomplete screening of positive polarization bound charges, as observed by scanning kelvin probe microscopy. Furthermore, x-ray photoelectron spectroscopy reveals that the flexoelectric polarization can downward bend the band alignment of the LFO layer and modulate the interfacial potential barriers. These results provide the way for experimental observations of the flexoelectric effect and deliver physical insight into deep understanding of interfacial electronic structures of flexoelectric-based devices.

Effect of Boron Doping on the Interlayer Spacing of Graphite.

Boron-doped graphite was prepared by the heat treatment of coke using B4C powder as a graphitization catalyst to investigate the effects of the substitutional boron atoms on the interlayer spacing of graphite. Boron atoms can be successfully incorporated into the lattice of graphite by heat treatment, resulting in a reduction in the interlayer spacing of graphite to a value close to that of ideal graphite (0.3354 nm). With an increase in the catalyst mass ratio, the content of substituted boron in the samples increased significantly, causing a decrease in the interlayer spacing of the boron-doped graphite. Density functional theory calculations suggested that the effects of the substitutional boron atoms on the interlayer spacing of the graphite may be attributed to the transfer of Π electrons between layers, the increase in the electrostatic surface potential of the carbon layer due to the electron-deficient nature of boron atoms, and Poisson contraction along the c-axis.

Antibacterial Activity and Mechanism of Polygonum orientale L. Essential Oil against Pectobacterium carotovorum subsp. carotovorum.

Infected by Pectobacterium carotovorum subsp. carotovorum (Pcc), the quality of Chinese cabbage could severely decline. Using chemical bactericides to control Pcc could cause food safety problems. Thus, we investigated the optimum extraction conditions, antibacterial activity, chemical compounds and antibacterial mechanism of Polygonum orientale L. essential oil (POEO) against Pcc in order to search a new way to control Pcc. The optimum extraction conditions of POEO (soaking time 2.6 h, extraction time 7.7 h and ratio of liquid to solid 10.3 mL/g) were optimized by response surface methodology. The minimum inhibitory concentration (MIC) of POEO against Pcc was 0.625 mg/mL. The control efficiency of protective activity of POEO against Pcc was 74.67~92.67%, and its curative activity was 76.00~93.00%. Then, 29 compounds were obtained by GC-MS; the prime compounds of POEO were phytol, phytone, n-pentacosane, 1-octen-3-ol and β-ionone. It was verified that, compared with control samples, POEO destroyed cell morphology. It increased surface potential, increased hydrophobicity, damaged cell walls, destroyed the integrity and permeability of cell membrane, reduced membrane potential (MP), and changed membrane protein conformation. It inhibited the activities of pyruvate kinase (PK), succinate dehydrogenase (SDH) and adenosine triphosphatase (ATPase). Briefly, the results of this study demonstrate that POEO showed effective inhibitory activity against Pcc, thus POEO could have potential application in controlling Pcc.

Efficacy of microconfined fluid mixing in a combined electroosmotic and pressure driven transport of complex fluid over discrete electrodes

This paper numerically investigates the mixing characteristics of an Oldroyd-B fluid flowing through a micro-channel having discrete electrodes along its walls driven by both electroosmotic force and pressure gradient. We consider both symmetric and asymmetric potential distributions along the wall while also probing the influence of fluid rheology and other physicochemical parameters of the problem. We report an improvement in mixing efficiency by increasing the relative strength of electroosmotic forcing and pressure gradient. It is also observed that the localized mixing efficiency decreases with an increase in surface potential. Fluid rheology changes the position of maximum efficiency depending on fluid properties without affecting mixing efficiency substantially. Compared with a continuous distribution, the five-electrode arrangement produces approximately equivalent mixing efficiency. We observe an increase in mixing efficiency at the micro-channel outlet as the gap between the electrodes increases. We have also analyzed the mixing characteristics for asymmetric charge distributions and illustrated the parameters controlling the flow dynamics. The results of the present study may prove helpful for the complete design and analysis of an active micromixer for the efficient transport of bio/polymeric fluids inside micro-channels.