Uniform Behavior Research Articles

Diffusive Memristors with Uniform and Tunable Relaxation Time for Spike Generation in Event-Based Pattern Recognition.

A diffusive memristor is a promising building block for brain-inspired computing hardware. However, the randomness in the device relaxation dynamics limits the wide-range adoption of diffusive memristors in large arrays. In this work, the device stack is engineered to achieve a much-improved uniformity in the relaxation time (standard deviation σ reduced from ≈12 to ≈0.32ms). The memristor is further connected with a resistor or a capacitor and the relaxation time is tuned between 1.13 µs and 1.25ms, ranging from three orders of magnitude. The hierarchy of time surfaces (HOTS) algorithm, to utilize the tunable and uniform relaxation behavior for spike generation, is implemented. An accuracy of 77.3% is achieved in recognizing moving objects in the neuromorphic MNIST (N-MNIST) dataset. The work paves the way for building emerging neuromorphic computing hardware systems with ultralow power consumption.

Comparative assessment of the biomass solar pyrolysis biochars combustion behavior and zinc Zn(II) adsorption

Biochars from solar pyrolysis of the waste straw, and dried sewage sludge, were assessed to recognize the possible application as unconventional adsorbents and fossils replacements for combustion purposes. The adsorption properties of the biochars were characterized by the BET (Brunauer, Emmett, and Teller) surface area, pore volumes, and the degree of Zn(II) adsorption from aqueous solutions. A higher removal degree of zinc ions of 26% was noted for biochars from dried sewage sludge with a BET area of 40.84 m2/g, compared to the waste straw biochars with a BET area of 1.67 m2/g and a corresponding removal degree of 16%. Both biochars presented more uniform combustion behavior compared to raw biomass, with the ignition and burnout temperatures similar to coal. Solar pyrolysis caused a reduction of the combustion kinetic steps, from multi-step combustion of the raw biomass to a single-step and two-step kinetic mechanisms for the sewage sludge and waste straw biochars respectively. It was found that the waste straw biochars are possible alternative fuels with a higher heating value of 22.6 MJ/kg, while sewage sludge chars presented better zinc adsorption of 2.09 mg/g and a total removal degree of 26%.

Surface Modification of TiO2 Nanotubes Prepared by Porous Titanium Anodization via Hydrothermal Reaction: A Method for Synthesis High-Efficiency Adsorbents of Recovering Sr Ions.

The recycling of strontium ions (Sr2+) from sea water has been well known for its good cost-effectiveness and environment friendliness. Herein, we modified the surface of TiO2 nanotubes (TNTs) prepared by porous titanium anodization via hydrothermal (HT) reaction and synthesized a highly efficient adsorbent for the repeated recycling of Sr2+. TNTs with a high specific surface area were manufactured on porous titanium by internal anodic oxidation. The as-prepared TNTs were treated by HT method to synthesize adsorption materials with a tubular bottom and grass-type top structure loaded with Na+. The surface cracks were eliminated by annealing pretreatment, and the investigation found that the 6 h HT reaction most effectively increased the Na+ content in the adsorbent. The as-synthesized adsorbents (HT-6TNTs) were used to recover Sr2+, and the maximum adsorption efficiency (approximately 100%) and adsorption equilibrium were observed within 10 h. Meanwhile, three consecutive cycles of adsorption experiments proved the uniform behavior of the HT-6TNTs in the reproducible recycling of Sr2+. In addition, by increasing the anodization time of TNTs from 0.5 to 3 h, the maximum adsorption capacity can be increased from 4.68 to 36.15 mg·unit-1, approximately 7.7 times higher.

Comparison of Brillouin Light Scattering and Density of States in a Supported Layer: Analytical and Experimental Study

We provide a detailed analytical calculation of the Brillouin light scattering (BLS) intensity of a layer on a substrate, taking into account both photoelastic and moving boundary (ripple effect) mechanisms, and give a comparison between BLS intensity and density of states (DOS) to determine the dispersion curves of longitudinal guided modes in the supported layer. In particular, in the case where the mismatch between the elastic parameters of the substrate and the adsorbed layer is high, such as in a PMMA layer on a Si substrate, we derive closed-form expressions of BLS and DOS and demonstrate a simple relationship between these two quantities. A very good agreement between experimental and theoretical BLS spectra was found and compared to theoretical DOS spectra. In particular, we show that while the peaks in the DOS present a uniform behavior, the BLS spectra follows a sine cardinal (sinc) function shape around a given frequency fixed by the chosen laser wavelength. The theoretical calculation is performed within the framework of the Green’s function approach.

Regulating the Uniform Na Deposition Behavior Using Atomically Dispersed Fe-Doped Mesoporous Carbon Nanospheres for High-Performance Sodium Metal Batteries

Sodium metal batteries (SMBs) are attracting intensive attention as an appealing candidate for high-energy-density batteries, owing to the high specific capacity, rich abundance, and low cost of metallic sodium (Na). However, the practical application of SMBs has been greatly hindered by the uncontrollable dendrite growth and unstable solid electrolyte interfaces, which are responsible for the poor Na stripping/plating reversibility and short lifespan. Herein, we report an atomically dispersed Fe-doped mesoporous carbon nanosphere (Fe-MCN) as a sodiophilic host for facilitating homogeneous Na nucleation and deposition behaviors. Benefitting from the advantages of uniform mesoporous structures with large surface areas and atomically dispersed Fe doped in the carbon nanospheres, low nucleation barriers and subsequent homogeneous deposition behavior of Na metal are achieved, which give rise to highly reversible stripping/plating performance and outstanding cycling stability. As a result, the Na||Cu cell based on Fe-MCN-modified Cu substrates exhibits outstanding electrochemical performance with a high Coulombic efficiency of 99.97% over 850 cycles, and an ultralong cycling lifespan of 2600 h at 1 mA cm–2 and 1 mA h cm–2 is demonstrated by the symmetric cell with Na@Fe-MCN@Cu anodes. Moreover, the Na3V2(PO4)3 full cell based on the Na@Fe-MCN@Cu anode guarantees outstanding cycling stability for 2000 cycles with a capacity retention as high as 84%, showing high potential in the practical application of SMBs.

Fully understanding the performance of nanocrystalline ternary Pr-Fe-B alloys with three typical phase constitutions

Pr2Fe14B phase exhibit similar intrinsic magnetic properties as Nd2Fe14B with even higher magnetic anisotropy field. Here we investigated the magnetic properties, exchange interaction, and corrosion resistance of melt-spun ternary Pr-Fe-B alloys with three typical compositions including Pr10Fe84B6, Pr12Fe82B6, and Pr14Fe80B6. The hard magnetic Pr2Fe14B phase is present in all alloys, while the α-Fe and RE-rich phases are additionally present in Pr10Fe84B6 and Pr14Fe80B6 alloys, respectively. Under optimum wheel speed of melt spinning, uniform single-phase behavior has been obtained for all alloys, which gives optimal hard magnetic properties. Based on exchange interaction behavior analysis, the nanocomposite Pr10Fe84B6 alloy and single phase Pr12Fe82B6 alloy show more uniform reversal domain nucleation behavior during demagnetization process. Importantly, Pr-Fe-B alloys show significant advantages over Nd-Fe-B alloys at cryogenic temperature. The hard magnetic properties increase with reducing temperature and extremely high coercivity has been obtained at 100 K. Pr10Fe84B6 alloy exhibits not only better low temperature stability but also much higher corrosion resistance than the Pr14Fe80B6 and Pr12Fe82B6 alloys. The existence of soft phase can improve the anti-corrosion properties, while the RE-rich phase is not advantageous to corrosion resistance although it enhances the coercivity.

Extraordinary ductility enhancement of Mg-Nd-Zn-Zr alloy achieved by electropulsing treatment

Mg-Nd-Zn-Zr (JDBM) alloy was studied as a candidate for biodegradable implant material because of its moderate mechanical properties, good biocompatibility, and favorable uniform degradation behavior. To verify whether JDBM alloy exhibits electroplasticity effect and then study the mechanism of electropulsing treatment on JDBM alloy, in this study, homogenized and pre-tensile deformed samples were treated by electropulsing. After the electropulsing treatment, the average grain size was refined due to recrystallization, micron-scale Mg12Nd secondary phases precipitated slightly, while the morphology of nanoscale Zr particles changed from rodlike to ellipsoidal shape. The elongation to failure (EL) increased obviously for the homogenized and pre-tensile deformed JDBM alloy samples after electropulsing treatment, accompanying with no obvious sacrifice of the yield strength (YS) for the former and an evident decrease of YS for the latter, mainly due to the reduction of the dislocation density. The YS decrement and EL increment (77.57%) for the latter are more apparent attributed to the higher density of dislocations introduced by pre-tensile deformation. Therefore, the electropulsing treatment can obviously improve the mechanical properties of JDBM alloy, especially for the plasticity. The present work opens a new window for the fabrication of JDBM alloy profiles with high mechanical properties, especially for the plasticity, such as the cold drawing wires and tubes for biomedical applications. It also could provide theoretical references for other magnesium alloy processing.

Impact of Substrate Defects on Vertical GaN Device Leakage Behavior

In this work, the effects of the substrate defects on the reverse leakage behavior of vertical GaN Schottky and p-i-n diodes are investigated. A direct connection between the reverse leakage behavior of GaN based vertical devices and the defect characteristics of the substrate was achieved. The difference in the leakage current can be as high as 6 orders of magnitude for vertical GaN p-i-n diodes at -200V, using HVPE substrate with inhomogeneous defect distributions (with dot-cores). For comparison, using HVPE substrate with uniform defect distribution (no cores), the p-i-n diodes show much more uniform leakage behavior at -200V, varying within only an order of magnitude. The wafers with inhomogeneous defect distribution possess periodically patterned core-centers with higher defect density (up to 108 cm-2) than regions in between cores, which have very low defect concentrations (as low as 104 cm-2). The full width at 0.01 maximum of the triple axis rocking curves (GaN (0004)) shows a large variation ranging from 60 to 930 arcsec. In comparison, wafers without the periodic cores have a uniform defect density (~106 cm-2) and show a small variation in the rocking curve FW0.01M, ranging only from 70 to 280 arcsec. For Schottky diodes fabricated on substrate with cores, positioning the devices away from the core-centers results in a reduction of the reverse bias leakage by 2-4 orders of magnitude at -10 V. Similar trend are also observed in the p-i-n diodes, with device further away from the core-centers showing lower leakage. The devices in the low defect concentration region (> 200 um away from core centers) on the wafer with cores outperform the devices from the wafer without cores, showing up to 2 orders of magnitude lower leakage current at -200 V. The results from this study show that the substrate defect density and distribution play an important role on the device leakage current and avoiding highly defective regions on the substrate will improve the performance of vertical GaN devices.

Brushed Metals for Rechargeable Metal Batteries.

Battery designs are swiftly changing from metal-ion to rechargeable metal batteries. Theoretically, metals can deliver maximum anode capacity and enable cells with improved energy density. In practice, these advantages are only possible if the parasitic surface reactions associated with metal anodes are controlled. These undesirable surface reactions are responsible for many troublesome issues, like dendrite formation and accelerated consumption of active materials, which leads to anodes with low cycle life or even battery runaway. Here, a facile and solvent-free brushing method is reported to convert powders into films atop Li and Na metal foils. Benefiting from the reactivity of Li metal with these powder films, surface energy can be effectively tuned, thereby preventing parasitic reaction. In-operando study of P2 S5 -modified Li anodes in liquid electrolyte cells reveals a smoother electrode contour and more uniform metal electrodeposition and dissolution behavior. The P2 S5 -modified Li anodes sustain ultralow polarization in symmetric cell for >4000 h, ≈8× longer than bare Li anodes. The capacity retention is ≈70% higher when P2 S5 -modified Li anodes are paired with a practical LiFePO4 cathode (≈3.2mAhcm-2 ) after 340 cycles. Brush coating opens a promising avenue to fabricate large-scale artificial solid-electrolyte-interphase directly on metals without the need for organic solvent.

An insight into polyscopoletin electrosynthesis by a quality-by-design approach

Scopoletin (SP) as a functional monomer for electropolymerization has recently been investigated in the context of molecularly imprinted polymers for biosensing applications. Herein we describe an in-depth analysis of the mechanisms involved in the electropolymerization of SP toward the optimization of the experimental conditions for applications in sensor studies. PolySP films have been in situ synthesized on a standard glassy carbon electrodes by varying three independent experimental parameters, and the output of the analysis has been evaluated in terms of the resulting electroactive area and surface coverage. A quality-by-design approach including design-of-experiments principles and response surface methodology produced unbiased observations on the most relevant parameters to be controlled during the electropolymerization of SP. By combining the output of electroactive area and surface overage, we highlighted a strong dependence on the monomer concentration and scan rate. Thus, an appropriate selection of these two parameters should be sought to have an optimal electropolymerization process, leading to uniform films and homogeneous surface behavior. This study shows that the application of multi-factorial analysis in a comprehensive design of experiments allows the systematic study of polymer electrosynthesis. Therefore, this research is expected to guide further efforts in the electropolymerization of several functional monomers.

Long-range coherent transmission of informations for collective dynamics in discrete-time models

The conditions on the stationary and the state-varying transition probabilities, which lead to the asymptotic occurrence of uniform collective behaviors in the corresponding discrete-time Markov chains, are established and analyzed. The conditions imply the existence of long-range coherent transmission of informations arising from the local communications. Based on the conditions, a measure, called the minimal time-interval of coherent transmission of informations, is introduced to characterize the speed of convergence towards a uniform collective behavior qualitatively. The numerical calculations on the proposed models indicate that the measure is consistent with the geometric distance of the corresponding network of dynamical system.

‘People are fed up; don’t mess with them.’ Non-quantificational Arguments and Polarity Reversals

Abstract The first sentence in the title means roughly: All the people around are tired. The second means: Do not mess with any of them. Even though the second sentence looks just like a negative counterpart of the first, it doesn’t have the expected compositional meaning: it doesn’t mean “do not mess with all the people”. This phenomenon is extremely general. It takes place with Bare Plurals, as in the title. It figures prominently in the behavior of Plural Definites (I spoke to the students in trouble ≅ ∀/I didn’t speak to the students in trouble ≅ ¬∃). It also takes place with Donkey pronouns (Every farmer who had a donkey sold it ≅ ∀/No man who had a donkey sold it ≅ ¬∃). These switches of quantificational force under polarity reversals call to mind Free Choice phenomena. In particular, a determiner like any is interpreted as a narrow scope existential in a sentence like I didn’t talk to any student in trouble ≅ ¬ ∃; however, in positive environments, the existential meaning of any emerges as strengthened to universal I spoke to any student in trouble ≅ ∀. It is tempting to conjecture that the source of this uniform behavior is a uniform mechanism. While these constructions (Free Choice any, Bare Plurals, Plural Definites, and Donkey pronouns) have been studied extensively, and insightful approaches to Plural Definites in terms of Free Choice mechanisms have also been proposed (Bar Lev 2018, 2021), a unitary analysis has not been attempted to the best of my knowledge. In spite of the many challenges that a unified analysis faces, it is worth a try, for, if successful, it would considerably push forward our understanding of a wide range of very diverse constructions.

Investigation of the Reverse Leakage Behavior and Substrate Defects in Vertical GaN Schottky and PIN Diodes

In this work, the effects of the substrate defect density and distribution on the reverse leakage behavior of GaN vertical Schottky diodes and p–i–n diodes are investigated. A direct connection between the reverse leakage behavior of GaN based vertical devices and the dislocation density of the underlying material was determined. The difference in the leakage current for devices on different locations of the wafer can be as high as 6 orders of magnitude (for p–i–n diodes) at −200V, for HVPE substrate with inhomogeneous but predictable defect distributions (GaN substrates with dot-core inversion domain features). For comparison, using HVPE substrates with uniform defect distribution (but with no cores), the p–i–n diodes show much more uniform leakage behavior, varying within only an order of magnitude, and that range fell within the much greater range of that for the inhomogeneous substrates. The substrates with inhomogeneous defect distribution proved to be useful to show the direct correlation. The topography measurements confirmed that the wafers with inhomogeneous defect distribution possess periodically patterned core-centers with higher defect density and larger lattice distortions surrounded by other regions, which have very low defect concentrations. Devices located away from the defective core-centers result in a reduction of the reverse bias leakage by over two orders of magnitude at −10 V for Schottky diodes. Similar trends are also observed in the p–i–n diodes; the devices close to the core centers show the highest reverse leakage (>0.01 A cm−2 at −200V). Devices further away from the core-centers (lower dislocation density) show lower reverse leakage current. Moreover, the p–i–n diodes on regions more than 300 μm away from the core-centers show the best leakage behavior (<10−7 A cm−2 at −200V) of all the devices, outperforming the devices on the substrates with uniform defect distribution (∼10−6 A cm−2 at −200V). The results from this study show that the substrate defect density and distribution play important roles in the device leakage current. X-ray topography is extremely effective for studying defect characteristics underneath individual devices. The use of the wafers with inhomogeneous, but predictable defect density clearly demonstrated the importance of low defect densities for high device performance.

A New Driver Model Based on Driver Response

In this paper, a new microscopic traffic model based on forward and rearward driver response is proposed. Driver response is characterized using the distance and time headways. Existing models such as the Intelligent Driver (ID) model characterize traffic flow based on a constant acceleration exponent. This exponent reflects uniform driver behaviour during different conditions which is unrealistic. Driver response is slow with a large distance headway and quick with a short time headway. Conversely, it is quick with a small distance headway and slow with a long time headway. Thus, a new microscopic traffic model is proposed which incorporates driver response. Results are given that show the proposed model provides better traffic stability than the ID model as this stability is based on traffic physics. Further, for effective utilization of road infrastructure, shorter time and longer distance headways are preferred. The performance of the ID and proposed models was evaluated over an 800 m circular road with a string of 15 vehicles for 120 s. These models are numerically discretized using the Euler scheme. The results obtained show that traffic queue dissemination with the proposed model is more realistic than with the ID model and the changes in density with the proposed model are smaller. This is because traffic dissemination with the proposed model is based on traffic parameters rather than a constant exponent.

Plausible sealing for gradual parametricity

Graduality and parametricity have proven to be extremely challenging notions to bring together. Intuitively, enforcing parametricity gradually requires possibly sealing values in order to detect violations of uniform behavior. Toro et al. (2019) argue that the two notions are incompatible in the context of System F, where sealing is transparently driven by potentially imprecise type information, while New et al. (2020) reconcile both properties at the cost of abandoning the syntax of System F and requiring user-provided sealing annotations that are not subject to graduality guarantees. Furthermore, all current proposals rely on a global form of dynamic sealing in order to enforce parametric behavior at runtime, which weakens parametric reasoning and breaks equivalences in the static language. Based on the observation that the tension between graduality and parametricity comes from the early commitment to seal values based on type information, we propose plausible sealing as a new intermediate language mechanism that allows postponing such decisions to runtime. We propose an intermediate language for gradual parametricity, Funky, which supports plausible sealing in a simplified setting where polymorphism is restricted to instantiations with base and variable types. We prove that Funky satisfies both parametricity and graduality, mechanizing key lemmas in Agda. Additionally, we avoid global dynamic sealing and instead propose a novel lexically-scoped form of sealing realized using a representation of evidence inspired by the category of spans. As a consequence, Funky satisfies a standard formulation of parametricity that does not break System F equivalences. In order to show the practicality of plausible sealing, we describe a translation from Funk, a source language without explicit sealing, to Funky, that takes care of inserting plausible sealing forms. We establish graduality of Funk, subject to a restriction on type applications, and explain the source-level parametric reasoning it supports. Finally, we provide an interactive prototype along with illustrative examples both novel and from the literature.

Performance analysis of melting phenomena in an ice-freezing type direct-contact heat exchanger

The present study endeavours to represent a latest concept of utilizing similar heat transfer fluid (HTF) and phase change material (PCM) in a direct contact type PCM heat exchanger (DCHEX). This technique has been found more effective during melting process. In the following investigation, a segment of the heat exchanger is numerically modelled to analyse the temporal behaviour of the latent heat energy storage system during the cycle of discharging. The transient numerical computation incorporates an iterative, finite volume method based on enthalpy-porosity technique for numerically model the phase change phenomena. For the analysis, water is used as working fluid. To show the performance enhancement of this technique during melting process, a series of simulations are performed to examine the impact of varying HTF inlet condition and flow rates. The changes in the configuration of the heat exchanger are studied. Heat exchanger parameters such as difference between inlet and outlet temperature (ΔT), heat release rate (Q), temperature effectiveness (θ) and volumetric heat transfer coefficient (Uv) are evaluated for all such cases. A uniform exit temperature of the HTF is observed for most of the time with significant increase in the heat transfer in the direct contact type heat exchanger. Three distinct stages namely initial, intermediate and final phases are observed during the melting process. During the initial phase the parameters exhibits uniform behaviour. In the intermediate phase there is significant drop and rise in the parameters while during the final phase the value of parameters diminishes except for Uv. Increasing HTF flow rate promotes increment in heat transfer rate while increasing the inlet temperature of HTF is more desirable to increase the overall heat transfer coefficient.

Achieving ultra-long lifespan Zn metal anodes by manipulating desolvation effect and Zn deposition orientation in a multiple cross-linked hydrogel electrolyte

Aqueous zinc-ion batteries (ZIBs) have received extensive attention due to the intrinsic advantages of high safety, low cost and environmental friendliness. But detrimental side reactions and dendrite problems resulting from high desolvation penalty and inhomogeneous Zn2+ flux at the interface severely hindered their practical applications. Herein, a novel polyacrylamide-poly (ethylene glycol) diacrylate-carboxymethyl cellulose (PMC) hydrogel electrolyte is designed to overcome these obstacles through reducing the desolvation energy barrier and guiding the preferential orientation of Zn deposition simultaneously. Theoretical calculation and experimental results reveal that the desolvation activation energy of the PMC hydrogel electrolyte (36.42 kJ mol−1) is substantially lower than that of conventional ZnSO4 aqueous electrolyte (62.31 kJ mol−1) due to the regulated Zn2+ solvation structure. Based on the high binding energy between amide groups and Zn2+, polymer chains in PMC also serve as facile Zn2+ transport channels to guide the uniform deposition behavior on the Zn (002) crystal surface, which is verified by the grazing incidence XRD analysis. Consequently, an ultra-long cycle life of 5000 h with a high coulombic efficiency of 99.5% is achieved by using the PMC hydrogel electrolyte. Considering the simple one-pot synthesizing method, the PMC hydrogel electrolyte provides new opportunities for developing practical ZIBs.

Addressing the social barriers to green stormwater infrastructure in residential areas from a socio-ecological perspective

Despite the well-recognized financial limitations, social aspects can also impact the adoption of green stormwater infrastructure (GSI) as it is ingrained in the socio-ecological system we live in. Thus, this work focuses on gaining an understanding of the public's perceptions of GSI by considering cognitive biases that hinder its adoption. This work is composed of two forms of human-subject studies, including an online-based survey and a series of semi-structured interviews. The survey (n = 510) was conducted to gauge public opinions toward GSI, whereas the interviews with representatives of major local regulatory agencies were to learn about the logistics for GSI implementation in Mecklenburg County, NC. The results were interpreted using the theory of planned behavior of rational actors. Statistical results showed a weak interpretation through this theory to explain the survey participants' intention to adopt GSI measures. This could suggest that the incorporation of irrationality, such as cognitive biases, could further enhance the predictability of the theory. At the same time, an inconsistency between the findings from the survey and the interviews was identified: most survey participants showed an overall uniform positive attitude, intention, and behavior regarding GSI practice adoption, whereas the interviewed experts all suggested a wide diversity on such terms. Suggestions were made based on the findings for better policy-making on public engagement for local regulatory agencies. This research aims to help local stormwater management authorities explore shortcomings in current stakeholder engagement plans to gain sustainable support for GSI implementation in urbanized areas.

Unraveling the mechanism of non-uniform zinc deposition in rechargeable zinc-based batteries with vertical orientation

• The non-uniform zinc deposition in the vertical direction is investigated. • Optical observations and stripping/platting model are combined in this work. • The non-uniform deposited zinc is started by nucleation site fracture. • The inhomogeneity is exacerbated by the non-uniform current and hydrogen evolution. Secondary zinc-based batteries demonstrate a bright prospect as a candidate for next-generation electrochemical energy storage devices. However, the inhomogeneous zinc deposition with vertical orientation during electrochemical stripping/platting cycles leads to battery failure quickly and thereby limits commercial applications of zinc-based batteries. In this work, the deposited electrochemical reaction is deeply investigated and the mechanism of inhomogeneous electrochemical deposition is proposed via in-situ optical observation and numerical analysis. During the deposited reaction, zinc atoms prefer to deposit on the nucleation sites on the electrode surface, changing the morphology of nucleation sites and leading to possible fractures. The fractural zinc fragments then accumulate at the bottom and connect to the bulk electrode, which initiate the inhomogeneous distribution in the vertical direction where the protrusion appears at the bottom, and the middle and top parts have rare deposited zinc. The inhomogeneity is exacerbated during stripping/platting reaction cycles due to the non-uniform local current density distribution on the emerging protrusion. Besides, the generated bubbles caused by hydrogen evolution exacerbate the inhomogeneous distribution via changing the ion distribution. Based on the conclusions, a uniform deposition behavior is achieved via modulating the ion distribution by the flowing electrolyte as a demonstration. The unraveled mechanisms can serve as a reference for the design of advanced zinc-based batteries with stable electrodes.

Characterization of Pseudomonas aeruginosa and Acinetobacter spp. in respiratory secretions of hospitalized patients in intensive care

Pseudomonas aeruginosa and Acinetobacter spp. are the microorganisms most frequently associated with serious healthcare-associated infections and death. The objective of the research consisted of characterizing the isolates of P. aeruginosa and A. spp. in respiratory secretions of patients hospitalized in the Clinical Surgical Hospital of Santa Clara, Villa Clara, Cuba between January 2014 and December 2018. A descriptive, longitudinal and retrospective study was carried out with the isolates of P. aeruginosa and A. spp. from the Clinical Surgical Hospital "Arnaldo Milián Castro" in the city of Santa Clara, Villa Clara province, Cuba between the months of January 2014 to December 2018. For the realization of this work, a discretionary and intentional sampling by criterion was selected. The population consisted of 2 207 isolates, and the sample consisted of 249 P. aeruginosa and 705 A. spp. The data were obtained from the record books of the respiratory samples section of the Microbiology Laboratory and were arranged in a documentary observation guide. A. spp., was the most frequently isolated microorganism in the intensive care units, with a uniform behavior during the entire series studied, while P. aeruginosa predominated in the first and fourth trimesters. A. spp., showed almost absolute levels of resistance throughout the study, while P. aeruginosa showed low percentages of resistance with a propensity to increase resistance. It is concluded that both microorganisms were the most frequently isolated in respiratory secretions in ICUs, surpassing in recent years’ other microorganisms, such as Gram-positive cocci and enterobacteria in general isolates and in HAIs, with marked prevalence rates for both genera, as well as an evident resistance, characterized by differences in relation to percentages, but with a propensity to increase it.