Double-step Process Research Articles

Maximizing surface reactivity: The impact of electrochemical oxidation as a polydopamine modification step

Melanin-based materials are highly versatile and widely utilized across various industries, thanks to their customizable surface properties and excellent biocompatibility. Dopamine, a well-studied precursor, has the remarkable ability to self-oxidize and form melanin-like compounds. This molecule can be tailored using cations during the oxidation process or via the chelation of hydroxyl groups in the final material. In order to explore the adaptability of dopamine-based melanin materials, our research focuses on producing particles using an innovative double-step process. The first oxidation is catalyzed by Y3+ in an electrochemical process, followed by further cyclization in a basic medium. We examined the resulting products to gauge the impact of the process on the final molecular arrangement and chelation capacity by utilizing Fe2+ as a cation probe. Surface reactivity was assessed using voltammetry techniques and electrochemical impedance spectroscopy. The results clearly indicate significant improvements in the molecular arrangement, demonstrating that the double-step process delivers higher material stability and superior surface reactivity compared to the conventional alkali self-oxidation method.

Chemical Bath Deposition of ZnO/ZnGa2O4 Core-Shell Nanowire Heterostructures Using Partial Chemical Conversion.

The development of innovative heterostructures made of ZnO nanowires is of great interest for enhancing the performances of many devices in the fields of optoelectronics, photovoltaics, and energy harvesting. We report an original fabrication process to form ZnO/ZnGa2O4 core-shell nanowire heterostructures in the framework of the wet chemistry techniques. The process involves the partial chemical conversion of ZnO nanowires grown via chemical bath deposition into ZnO/ZnGa2O4 core-shell nanowire heterostructures with a high interface quality following their immersion in an aqueous solution containing gallium nitrate heated at a low temperature. The double-step process describing the partial chemical conversion relies on successive dissolution and reaction mechanisms. The present finding offers the possibility to fabricate ZnO/ZnGa2O4 core-shell nanowire heterostructures at low temperatures and over a wide variety of substrates with a large surface area, which is attractive for nanostructured solar cells, deep-UV photodetectors, and piezoelectric devices.

A New Double-Step Process of Shortening Fibers without Change in Molding Equipment Followed by Electron Beam to Strengthen Short Glass Fiber Reinforced Polyester BMC.

It is vital to maximize the safety of outdoor constructions, airplanes, and space vehicles by protecting against the impact of airborne debris from increasing winds due to climate change, or from bird strikes or micrometeoroids. In a widely-used compression-molded short glass fiber polyester bulk-molded compound (SGFRP-BMC) with 55% wt. CaCO3 filler, the center of the mother panel has lower impact strength than the outer sections with solidification texture angles and short glass fiber (SGF) orientations being random from 0 to 90 degrees. Therefore, a new double-step process of: (1) reducing commercial fiber length without change in molding equipment; followed by a (2) 0.86 MGy dose of homogeneous low-voltage electron beam irradiation (HLEBI) to both sides of the finished samples requiring no chemicals or additives, which is shown to increase the Charpy impact value (auc) about 50% from 6.26 to 9.59 kJm-2 at median-accumulative probability of fracture, Pf = 0.500. Shortening the SGFs results in higher fiber spacing density, Sf, as the thermal compressive stress site proliferation by action of the CTE difference between the matrix and SGF while the composite cools and shrinks. To boost impact strength further, HLEBI provides additional nano-compressive stresses by generating dangling bonds (DBs) creating repulsive forces while increasing SGF/matrix adhesion. Increased internal cracking apparently occurs, raising the auc.

Removal of hardness and silicon by precipitation from reverse osmosis influent: Process optimization and economic analysis

The removal of hardness and silicon in the reverse osmosis influent is urgently desirable in view of wastewater purification and reuse. However, the development of cost-effective method reducing the hardness and silicon to low level is challenging. Herein, the single step process and double step precipitation process were proposed, aiming at minimize the adverse effect of influent wastewater on reverse osmosis membranes. The optimal dosages of precipitants (FeCl3 and MgCl2) and the effects of pH values and time were investigated. In the double step process, the concentrations of total hardness and silicon reached the lowest values (11.0 mg·L−1 and 2.1 mg·L−1) by adding 400 mg·L−1 MgCl2 and 300 mg·L−1 FeCl3. Subsequently, four schemes for the wastewater treatment were proposed, which scheme D using both FeCl3 and MgCl2 as precipitants obtained the lowest cost (1.20 $·t−1). This work could provide technological support for removing total hardness and silicon from industrial wastewater and industrial wastewater recycling.

A performance comparison of cyclopentyl methyl ether (CPME) and hexane solvents in oil extraction from sewage sludge for biodiesel production; RSM optimization

A comparative study of oil extraction from secondary dry sludge was performed via Reflux and Folch methods by cyclopentyl methyl ether (CPME) and hexane as green and organic solvents, respectively. Response surface methodology based on Box-Behnken design (RSM-BBD) was utilized to optimize and predict the impact of influential factors, including sludge amount (4–6 g), the volume of solvent (12–16 mL), and extraction time (2–6 h). The maximum oil extraction efficiency was 8.078 % and 4.076 % under the optimal conditions: 5.15 g, 16 mL, 2 h for CPME, and 4.22 g, 11 mL, 2 h for hexane. The raw sludge was characterized by FESEM and XRF analyses, while the extracted oil characteristics were determined by GC-Mass and FTIR methods. As a result, the Folch method by CPME solvent was a more efficient way to extract oil from sewage sludge. Finally, biodiesel was produced via the transesterification double-step process (TDSP) using NaOH/Clinoptilolite-Fe3O4 magnetic catalyst. The production efficiency of biodiesel from the oil extracted by CPME and hexane is 6.94 % and 4.1 %, respectively. The maximum yield of biodiesel production was6.94 % under the optimum reaction conditions: methanol to oil molar ratio of 10:1, catalyst weight of 0.45 wt%, and reaction time of 2.5 h with the help of the electrolysis method.

Morphological insights associated to instantaneous nucleation and growth in Cr(III) electrodeposition on nickel in aqueous media

In this work, experimental evidence of instantaneous nucleation and growth transients were observed for Cr(0) electrodeposits in aqueous electrolytes, using Cr(III) as precursor species in a double potential step process. This progression occurs via a Cr(II) intermediate, which should be stabilized in aqueous media to afford its proper reduction. This mechanism is rarely observed in aqueous media due to rapid onset of hydrogen evolution and adsorption due to both the acidity and chemical composition of the electrolytic medium employed. Using this approach to prepare a potentiostatically controlled electrodeposit, afforded functional coating on a substrate which is employed for industrial applications (Ni). The morphological features observed from microscopic analysis of the surfaces allowed considering that such instantaneously formed nuclei are important in determining the grain size of the final coating and as such could be controlled in a more significant way with this potentiostatic technique, providing an alternative to the galvanostatic classic approach.

Chemical Synthesis of β-Ga2O3 Microrods on Silicon and Its Dependence on the Gallium Nitrate Concentration.

β-Ga2O3 microrods have attracted increasing attention for their integration into solar blind/UV photodetectors and gas sensors. However, their synthesis using a low-temperature chemical route in aqueous solution is still under development, and the physicochemical processes at work have not yet been elucidated. Here, we develop a double-step process involving the growth of α-GaOOH microrods on silicon using chemical bath deposition and their further structural conversion to β-Ga2O3 microrods by postdeposition thermal treatment. It is revealed that the concentration of gallium nitrate has a drastic effect on tuning the morphology, dimensions (i.e., diameter and length), and density of α-GaOOH microrods over a broad range, in turn governing the morphological properties of β-Ga2O3 microrods. The physicochemical processes in aqueous solution are investigated by thermodynamic computations yielding speciation diagrams of Ga(III) species and theoretical solubility plots of GaOOH(s). In particular, the qualitative evolution of the morphological properties of α-GaOOH microrods with the concentration of gallium nitrate is found to be correlated with the supersaturation in the bath and discussed in light of the standard nucleation and growth theory. Interestingly, the structural conversion following the thermal treatment at 900 °C in air results in the formation of pure β-Ga2O3 microrods without any residual minor phases and with tunable morphology and improved structural ordering. These findings reporting a double-step process for forming high-quality pure β-Ga2O3 microrods on silicon open many perspectives for their integration onto a large number of substrates for solar blind/UV photodetection and gas sensing.

Epitaxial TiO2 Shell Grown by Atomic Layer Deposition on ZnO Nanowires Using a Double-Step Process and Its Beneficial Passivation Effect

Owing to the chemical instability of ZnO nanowires and to their large surface area exhibiting a high density of traps, the use of a protective, passivating shell plays a major role in the performan...

Involvement of Aquaporins in the Pathogenesis, Diagnosis and Treatment of Sjögren's Syndrome.

Sjögren’s syndrome (SS) is a chronic autoimmune disease characterized by lymphocytic infiltration of salivary and lacrimal glands resulting in diminished production of saliva and tears. The pathophysiology of SS has not yet been fully deciphered. Classically it has been postulated that sicca symptoms in SS patients are a double step process whereby lymphocytic infiltration of lacrimal and salivary glands (SG) is followed by epithelial cell destruction resulting in keratoconjunctivitis sicca and xerostomia. Recent advances in the field of the pathophysiology of SS have brought in new players, such as aquaporins (AQPs) and anti AQPs autoantibodies that could explain underlying mechanistic processes and unveil new pathophysiological pathways offering a deeper understanding of the disease. In this review, we delineate the link between the AQP and SS, focusing on salivary glands, and discuss the role of AQPs in the treatment of SS-induced xerostomia.

Primary concept of nickel toxicity - an overview.

Toxic metals, including excessive levels of essential metals tend to change biological structures and systems into either reversible or irreversible conformations, leading to the derangement of organ functions or ultimate death. Nickel, a known heavy metal is found at very low levels in the environment. Nickel is available in all soil types and meteorites and also erupts from volcanic emissions. In the environment, nickel is principally bound with oxygen or sulfur and forms oxides or sulfides in earth crust. The vast industrial use of nickel during its production, recycling and disposal has led to widespread environmental pollution. Nickel is discharged into the atmosphere either by nickel mining or by various industrial processes, such as power plants or incinerators, rubber and plastic industries, nickel-cadmium battery industries and electroplating industries. The extensive use of nickel in various industries or its occupational exposure is definitely a matter of serious impact on human health. Heavy metals like nickel can produce free radicals from diatomic molecule through the double step process and generate superoxide anion. Further, these superoxide anions come together with protons and facilitate dismutation to form hydrogen peroxide, which is the most important reason behind the nickel-induced pathophysiological changes in living systems. In this review, we address the acute, subchronic and chronic nickel toxicities in both human and experimental animals. We have also discussed nickel-induced genotoxicity, carcinogenicity, immunotoxicity and toxicity in various other metabolically active tissues. This review specifically highlighted nickel-induced oxidative stress and possible cell signaling mechanisms as well.

185 - Linear relationship of cells in vs. cells out with the clinimacs plus

There is a substantial body of experience using the CliniMacs Plus immunomagnetic cell separator to produce modified grafts for hematopoietic progenitor transplantation. In general, graft preparation has been performed on starting products of varying cellularity, and the total recovered product from CliniMacs manipulation has been administered in its entirety. This, in turn, leaves cell dosing as a confounding variable when evaluating clinical outcomes resulting from treatment with CliniMacs processed grafts. We hypothesize that the relationship between starting numbers of targeted cell types and final numbers may be sufficiently linear that final cell numbers might be pre-determined by controlling the number of targeted cells in the pre-processing products. We have reviewed the data of pre-processing cell numbers and the resultant targeted cell recoveries from our CD34 selection and CD45RA depletion single step processes and from our NK cell selection double step process. Using a Pearson's linear regression model, we analyzed each identified cell type, comparing the number of those cells input into the CliniMacs process with the number of the same cell type recovered at the end of processing. From these analyses, we obtained for each cell type a regression equation, y=ax+b, wherein a is the slope of the regression line and also the average recovery of the targeted cell, and b is the y axis intercept of the best fit line. Additionally, we obtained an R2 value, which identifies the fractional certainty that the input cell value predicts the output value. This analysis has revealed that for the identified cell types, there is a linear relationship, suggesting a predictability of final product counts from starting product counts with 65–94 percent certainty (R2). The resultant predictive model incorporates all processing steps, including washes, antibody incubations and the actual CliniMacs separation processing. It should be noted in particular that a linear relationship is present even in our NK cell enrichment processes which comprise a CD3 depletion followed serially by a CD56 selection. We conclude that maintaining minimal variation in the conduct of processing steps, combined with a non-varying CliniMacs process, produces a sufficiently predictable final product to allow for increased precision in cell dosing. Table ICliniMacs plus processing linearity. Manipulation Cell Type Targeted N Regression Line Slope R-square CD34 Selection CD34 positive 309 0.60 0.94 CD45RA depletion CD34 positive 64 0.56 0.88 CD45RA depletion CD3 positive/CD45RA negative 64 0.39 0.65 CD3 depletion followed by CD56 selection CD56 positive 151 0.53 0.80 CD3 depletion followed by CD56 selection CD56 positive/CD3 negative 151 0.53 0.80 Open table in a new tab

HLA-DQ genetics in children with celiac disease: a meta-analysis suggesting a two-step genetic screening procedure starting with HLA-DQ β chains.

BackgroundSpecific HLA-DQ genes have been recognized as necessary - but not sufficient - factors for the occurrence of Celiac Disease (CD). Through a meta-analysis, evaluating the distribution of CD-related HLA genotypes in children, we aimed at providing insights for a potential widened screening strategy.MethodsAfter a systematic search on the association between class II HLA genes and CD in children, 46 publications were obtained and assessed for eligibility. A total of 13 eligible studies were submitted to data extraction and analysis (10 case-control studies and 3 cohort studies). Case-control studies collectively enrolled 740 CD patients and 943 controls.ResultsIn the population-stratified analysis, the following alleles conferred a significantly increased risk for CD: HLA-DQB1*02 (odds ratio [OR]=10.28) and HLA-DQB1*03:02 (OR=2.24). By drafting a risk gradient to develop CD according to HLA genetic background, the highest risk is confirmed to exist for DQ2/DQ2 homozygous subjects, regardless of the ethnicities (OR=5.4). Actually, the genotype DQ2/β2 showed basically the same risk (OR=5.3). Indeed, no differences have been found in CD risk between DQ2/β2 and DQ2/DQ2, as well as between DQ8/β2 and DQ2/DQ8, and between β2/DQX and DQ2/X.ConclusionThe HLA-DQB1*02:01 allele is present in more than 90% CD children. In the perspective of a widened pediatric population screening for CD, a double-step process might be suggested: HLA-DQB1*02:01 might be investigated first and, only if this result is positive, children might be candidate for a prospective serologic screening, as a second step.

Identification of Behavior of Linearly Viscoelastic Materials from Experiments on Relaxation with Initial Area of Increasing Strain

The problem of the determination of the relaxation functions of linearly viscoelastic materials is studied in experiments with a double-step strain process (ramp test); strain increases at the first stage and is constant at the second stage. The experimental data on the dependency of stresses on time are analyzed in three ways with a subsequent comparison of results. The first method requires fulfillment of the 10 rule and uses the backward recurrence method; the second is based on the formulas of approximate integration. In the third, it is immediately assumed that the relaxation function can be represented by a truncated Prony series. For the Maxwell linear model, the 10 rule was analyzed analytically.

Life cycle assessment of the transesterification double step process for biodiesel production from refined soybean oil in Brazil.

Biodiesel has been attracting considerable attention as being a renewable, biodegradable, and nontoxic fuel that can contribute to the solution of some energy issues as it presents potential to help mitigate climate change. The Life Cycle Assessment of biodiesel from soybean oil (transesterification double step process) was carried out herein. A pilot plant was considered, designed to produce 72L of biodiesel in daily continuous flow, throughout a lifetime of 15years (8000 annual hours). The materials and equipment utilized in the construction of the plant were considered as well as the energy and substances required for the production of biodiesel. Environmental impact assessment method IPCC 2013 GWP 100a was utilized within the SimaPro software to express the final result in kg CO2-equivalent. The results quantified the CO2 emissions associated with biodiesel production throughout the lifetime of the production plant (15years), resulting in a total value of 1,441,426.05kg CO2-eq. (96,095.07kg CO2-eq. per year), which was equivalent to 4.01kg CO2-eq. per liter of biodiesel produced. Decrease of environmental loads associated with the production of biodiesel could include improvements on the handling of biomass agriculture and on the technology production of biodiesel.

OTIMIZATION OF TRANSESTERIFICATION DOUBLE STEP PROCESS (TDSP) TO THE PRODUCTION OF BIODIESEL THROUGH DOEHLERT EXPERIMENTAL DESIGN

In this work, Doehlert experimental design was used to optimize the Transesterification Double Step Process (TDSP) method of methyl soybean oil biodiesel production which starts with a basic catalysis followed by an acidic catalysis. The conversion values were calculated from NMR spectra. Response surface was used to show the results of the interactions between the variables. This experimental design evaluated variables like catalyst and alcohol amount for the basic catalysis and time and temperature for the acidic catalysis. According to results obtained after Doehlert design application the alcohol amount was the main factor that influenced on the basic catalysis but for the acidic catalysis both time and temperature are important and their effects are opposite. It resulted on excellent conversions for both steps obtaining for the basic catalysis about 100% when was used like optimal conditions catalyst amount equal to 0.40 g and volume of methanol equal to 60 mL and for the acidic catalysis about 99% when was used like optimal conditions temperature of 65 °C and 90 minutes for reaction time.

3C-SiC Polycrystalline Films on Si for Photovoltaic Applications

The electrical and optical properties of n-doped polycrystalline 3C-SiC films grown on 6 inches Si wafers have been investigated as a function of precursor gases, deposition temperature and C/Si ratio. The Si/SiC interface has been optimized, eliminating the voids formation through a double temperature step process and by introducing a thin not intentionally doped layer. Films with high surface roughness, favourable for light trapping in photovoltaic applications, and with resistivity around 20 mOhm cm have been obtained for C/Si ratio close to 1. Simple solar cells have been also manufactured and proved the functionality of poly 3C-SiC/Si heterojunction solar cell. Increased quantum efficiency in the range 300-500 nm has been observed, compared to amorphous Si, making poly 3C-SiC heterojunction solar cells interesting for high temperature applications or water splitting.

Decontamination of protective clothing against radioactive contamination

The aim of this study is to describe the experimental results of external surface mechanical decontamination of the studied materials forming selected suits. Seven types of personal protective suits declaring protection against radioactive aerosol contamination in different price ranges were selected for decontamination experiments. The outcome of this study is to compare the efficiency of a double-step decontamination process on various personal protective suits against radioactive contamination. A comparison of the decontamination effectiveness for the same type of suit, but for the different chemical mixtures ((140)La in a water-soluble or in a water-insoluble compound), was performed.

Effect of double-step steam explosion pretreatment in bioethanol production from softwood.

The study investigated the production of bioethanol from softwood, in particular pine wood chip. The steam explosion pretreatment was largely investigated, evaluating also the potential use of a double-step process to increase ethanol production through the use of both solid and liquid fraction after the pretreatment. The pretreatment tests were carried out at different conditions, determining the composition of solid and liquid fraction and steam explosion efficiency. The enzymatic hydrolysis was carried out with Ctec2 enzyme while the fermentation was carried out using Saccharomyces Cerevisiae yeast "red ethanol". It was found that the best experimental result was obtained for a single-step pretreated sample (10.6 g of ethanol/100 g of initial biomass dry basis) for a 4.53 severity. The best double-step overall performance was equal to 8.89 g ethanol/100 g of initial biomass dry basis for a 4.27 severity. The enzymatic hydrolysis strongly depended on the severity of the pretreatment while the fermentation efficiency was mainly influenced by the concentration of the inhibitors. The ethanol enhancing potential of a double-step steam explosion could slightly increase the ethanol production compared to single-step potential.

Flue Gas CO2 Mineralization Using Thermally Activated Serpentine: From Single- to Double-step Carbonation

Abstract This communication explores the carbonation potential of activated serpentine at flue gas conditions. A first series of single-step batch experiments was performed varying the temperature and the slurry density to systematically assess the precipitation regime of the relevant Mg-carbonates and the fate of the Si species in solution. The results suggested that the reaction progress was hindered by a passivating layer of re-precipitated silica, quartz, or carbonates, as well as by equilibrium limitations. Among several strategies that were tested to overcome these limitations, a simple double-step process that is driven by a temperature swing in combination with a low-level CO2 pressure swing is presented. Exploratory experiments are shown that prove the viability of our process, first by applying a discontinuous method, and secondly by implementing a methodology to cycle the liquid phase continuously between a dissolution reactor and a precipitator. In this way, it was possible to produce highly pure Mg-carbonates that may serve various industries.

Radiation-assisted Frenkel-Poole transport in single-crystal diamond

The measurement of the density of occupied states as a function of the applied electric field, performed on single-crystal chemical vapour deposition diamond by x-ray modulated photocurrent technique, is reported. Two regimes of non-linear charge transport were observed: a classical Frenkel-Poole (FP) process at high electric fields (>6800 V/cm), and a radiation-assisted transport mechanism at intermediate electric fields (2000 to 6800 V/cm), consisting of a double-step process in which the direct re-emission into the extended band occurs following multiple photo-induced FP-like hopping transitions.