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Lake Sevan is a meso-eutrophic water body, which was severely impacted by anthropogenic level decrease, pollution and eutrophication during the last century. Starting in the 1970s, these processes resulted in the formation of an oxygen-depleted hypolimnion during summer–autumn stratification of the lake. In this work, we demonstrate for the first time that eutrophication of the lake leads not only to the full depletion of oxygen and nitrate in the hypolimnion but as well to the presence of sulfate-reducing microorganisms and toxic hydrogen sulfide. Concentrations of hydrogen sulfide in the hypolimnion of Major and Minor Sevan in October were as high as 9 and 39 μM, respectively. In October 2019, 66 % of lake's bottom was covered by sulfidic waters, while the fraction of sulfidic water volume reached 19 %. Values of δ34S for hypolimnetic sulfide are lower by only 7–12 ‰ compared to epilimnetic sulfate, while δ33S values of sulfide are similar to the δ33S values of sulfate. These isotopic fingerprints are not consistent with microbial sulfate reduction as the sole source of hydrogen sulfide in the hypolimnion. We attribute the formation of a sulfidic deep-water layer to a combination of microbial sulfate reduction in the water column and diffusion of hydrogen sulfide from the sediments. [ABSTRACT FROM AUTHOR]

UV-curable particle-free ceramic compositions for stereolithography-based 3D printing technologies present a promising alternative to the commonly used particle-based compositions. So far, such compositions were mainly based on solutions of pre-ceramic polymers which limit their applications to silicon-containing materials. However, the application of particle-free inks for the fabrication of other ceramic materials, in particular dense polycrystalline ones, is very little explored. We present a new and general fabrication approach based on all-solution compositions, by combining sol–gel chemistry and photopolymerization, for obtaining dense 3D ceramic structures by DLP printing. The process is demonstrated here for the fabrication of barium titanate (BaTiO3). By using chelating solvent and monomer, a stable UV-curable solution is obtained. An aging period of 8–14 days was crucial for obtaining dense ceramic objects without any secondary phases. The heat treatment was found to affect the microstructure, density and hardness of the resulting ceramics. The presented process enables obtaining objects free of carbon materials, having a density as high as 98% of the theoretical value, and a hardness of 4.3 GPa. [ABSTRACT FROM AUTHOR]

A sensitive and robust method for detection of free and metal-complexed cyanide in solutions is described. The method does not require a distillation step and is applicable for both low ionic strength and sea-water samples. The method is based on the reaction of cyanide with potassium tetrathionate followed by high-performance liquid chromatography (HPLC) separation and UV detection of formed thiocyanate. The detection limit of the method is 250 nmol L−1 cyanide (6.5 µg L−1 CN−) without a pre-concentration step. Storage for three days does not significantly change the results. The sum of free and weak metal-complexed cyanide can be measured by tetrathionate derivatization at a pH of 10. The sum of free, weak metal-complexed cyanide, iron(II) and iron(III)-complexed cyanides may be measured by tetrathionate derivatization at pH 4.4. Derivatization requires heating to 90°C for 20 min at pH = 10 and for 12 h at pH = 4.4. Weighted mean recoveries for free, iron(II), iron(III), nickel(II), silver(I), Cd(II) and Zn(II) complexed cyanide were in the range of 87 to 112% and weighted standard deviations were in the range of 1.7 to 10.0%. The method is not applicable for cyanide complexes of gold and cobalt. We illustrate an application of cyanide quantification using pore-waters from the Delaware Great Marsh. [ABSTRACT FROM AUTHOR]

This review describes the interfacial behavior of biomolecules, which were converted to more hydrophobic derivatives by covalent attachment of hydrophobic chains. The molecules presented are proteins (glucose oxidase, immunoglobulin G, gelatin, ovalbumin) and polysaccharides (carboxymethylcellulose, pullulan). In general it was found that such hydrophobically modified biomolecules have enhanced surface activity and ability to penetrate into phospholipid monolayers. In addition, it has been demonstrated, that such molecules can be used as efficient emulsifiers and foaming agents, and in unique biomedical application based on combining the surface activity and recognition ability. [ABSTRACT FROM AUTHOR]

In the present work, we examined the antibacterial activity of novel silver@cuprous oxide core-shell/hydroxyapatite (Ag@Cu2O/HAp) hetero-nanohybrids against Gram-positive Staphylococcus aureus and Gram-negative Escherichia coli bacteria. The hydrothermal technique was used to easily synthesise Ag@Cu2O/HAp core-shell nanohybrid structures. Immobilisation of Ag@Cu2O core shells on HAp nanoparticles was done by controlling the relative concentrations of Ag, Cu2O, and HAp. The Ag@Cu2O/HAp nanohybrids were characterised using XRD, FTIR, Raman, UV-vis, SEM, EDX, TEM, and SAED methods. By observing the growth of S. aureus and E. coli populations in the presence and absence of Ag, Ag@Cu2O, HAp, and Ag@Cu2O/HAp nanoparticles, their antibacterial impact was compared. MIC Alamar Blue assay was performed to study the cytotoxicity of Ag@Cu2O/HAp nanomaterials. In addition, reactive oxygen species (ROS) studies were conducted to understand the type of active species produced under light and dark conditions. The possible photochemical and antibacterial mechanisms of the Ag@Cu2O/HAp nanohybrids against S. aureus and E. coli bacteria were proposed. In addition, the promising antibacterial nature of Ag@Cu2O/HAp materials suggests that they are good candidates for industrial and biomedical applications. [ABSTRACT FROM AUTHOR]

Direct ink writing is an innovative technique developed to replace traditional fabrication techniques, such as lithography, for flexible electronics. Herein, a novel ternary cadmium sulfide quantum dot-doped reduced graphene oxide-bismuth oxide (CrGB) heterojunction semiconductor material was prepared via an in situ hydrothermal technique. After that, an electroconductive ink consisting of carbon nanotubes (CNTs) and CrGB was prepared. The ink was used to fabricate a flexible circuit using nanocrystalline cellulose (NCC) paper. The circuit exhibited excellent conductivity of 3900 S cm−1. Furthermore, the recyclability and biodegradation of the circuit suggest the feasibility of constructing low-cost and environmentally benign materials and devices. An in situ hydrothermal technique was used to prepare CrGB heterojunction semiconductor nanocomposites with different loadings (wt.%) of Bi2O3 nanoparticles was done successfully. Investigation of the influence of weight percent loadings of Bi2O3 and CdS QDs on the physicochemical, optoelectronic and electrical properties of the prepared nanocomposites was carried out. TEM micrograph of the CrGB semiconductor showed a dense and uniformly deposited particles of CdS QDs and Bi2O3 nanoparticles on the RGO interface. A novel ternary electroconductive ink (CrGBC) was prepared from the mixture of CrGB nanocomposite and CNTs, which exhibited a significantly improved contact angle of 31°. Also, a flexible, transparent and biodegradable thin-film was prepared from NCC. Fabrication of a recyclable and biodegradable smart electronic circuit, with the prepared ink and NCC thin-film as a substrate. This was further applied to light an LED bulb to confirm its conductivity properties. Recyclability and biodegradation (using fungi) of the fabricated smart device was successfully done. This suggest the possibility of designing biofriendly and low-cost smart devices. [ABSTRACT FROM AUTHOR]

Coal mining activities produce coal mine drainage which becomes a potential pollutant of regional groundwater. The temperature and microbial community in aquifers and rock formations change with coal mining depth increases. While the influence mechanisms of temperature and microorganisms on the hydrochemical characteristics of mine water are poorly understood. This study investigated a typical minefield in north China and performed the water–rock (coal) incubation experiments to explore the effect of temperature and microorganisms on the chemical characteristics of mine water. Hydrochemistry type of coal mine water in the goafs and main water-filled aquifers of Xinjulong coal mine was the SO4–Na type. Proteobacteria and Firmicutes were the main bacterial phyla in the coal mine water. The increasing closure time of goafs decreased SO42− concentration and increased the microbial diversity in mine water. The 28-day incubation experiments found Na+ and SO42− slightly increased by 5.13 and 6.67%, respectively, and HCO3− decreased by 14.33% when the temperature rose by 10 °C. The Shannon index of the bacterial community in water–coal system increased by 6.7% and the relative abundance of Hydrogenophaga decreased by 22.7%, while that of Thiobacillus increased by 31.56%. The microbial activities decreased Na+ and SO42− by 2.31 and 4.95%, respectively, but increased HCO3− by 7.59%. The functional prediction showed the microorganisms undergone sulfur conversion reactions and affected the dissolution of ions in mine water. The results were crucial for understanding the mutual effects of temperature and microorganisms on the hydrochemical characteristics of coal mine water. [ABSTRACT FROM AUTHOR]

Ionogels are a promising family of soft, conducting materials having, high ionic conductivity and wide operating temperature. 3D printing is an enabling technology undergoing, phenomenal expansion in recent years, propelling ionogels as next-generation material. This work showcases preface to ionogels, its classification, preparation, 3D printing techniques to print ionogels and properties of sensors formed from ionogels, which are imparted via various 3D printing are compared by taking into account of difference in poly ionic liquid (PIL), which is a class of polyelectrolytes, having conducting ions which are poorly coordinated, polymeric backbones with ionic liquid in every repeating unit. [ABSTRACT FROM AUTHOR]

Multi-material manufacturing through the hybridisation of printed electronics and additive manufacturing has gained great interest recently. However, such hybridisation attempts are not trivial due to the need for functional material development and compatible process identification, as well as further performance understanding, comprehensive characterisation and long-term reliability evaluation of multi-material parts. While some multi-material structures from functional materials such as silver inks have been demonstrated via the integration of direct writing systems into stereolithography or material extrusion platforms, the performance assessment and characterisation of parts manufactured using such integrated systems is still required. Therefore, this research presents a comprehensive assessment of multi-material structures manufactured using syringe deposition and material extrusion platforms. Test specimens were subjected to various characterisation activities such as thickness measurement, resistance measurement, roughness tests, wettability measurement, adhesion tests, and morphological analysis. Results and statistical analyses suggested that the dry thickness and conductivity of deposited films were dependent on the substrate material. Adhesion between the conductive film and substrate was affected by both substrate material and ink deposition angle. Also, the interaction of conductive films with polycarbonate substrate was found to be noticeably better among all substrates due to low resistivity and enhanced adhesion at low thicknesses. [ABSTRACT FROM AUTHOR]

A coronene-like graphitic nanoribbon was recently synthesised as a potential candidate for applications in nanoelectornics due to its unique structural characteristics in contrast with other nanomaterials. It is a planar, thin, finite, and quasi-one-dimensional carbon-based material with novel characteristics. The coronene-like graphitic nanoribbon is constructed using multiple units of a finite dimensional coronene structure linked together in a chain of armchair and zigzag isomers. In this article, we compute the topological properties based on distance and degrees of armchair and zigzag nanoribbon isomers by adopting the orthogonal partition techniques. Our results on entropy measures demonstrate that armchair and zigzag nanoribbon isomers exhibit isentropic structures. We have computed the vertex partitions, 13 C NMR and ESR spectra using distance degree sequence vectors and spectra of armchair and zigzag isomers. Furthermore graph spectral properties of the two isomers are computed which reveal that the zigzag nanoribbons are kinetically more stable than the corresponding armchair isomers. [ABSTRACT FROM AUTHOR]

Ethylene spent caustic with strong alkalinity, high chemical oxygen demand (COD) and toxicity could not be directly discharged without pretreatment. In this paper, the composition of spent caustic from a petrochemical enterprise was analyzed. Effects of oxidants, reaction temperature, pressure and residence time on the removal ratio of COD in the spent caustic were investigated. The oxidation reaction mechanism of main organic sulphides in the spent caustic was discussed. Results show that COD of the ethylene spent caustic is ∼ 24.5 g/L, the main compositions are S2- and disulphides including a small amount of ketones and phenolic organics. The removal ratio of S2- in spent caustic is up to 100%, and the removal ratio of COD is over 83% at 180 °C with the pressure of 2 MPa and residence time of 15 min using oxygen as an oxidant. Taking dimethyl disulphide as an example, dimethyl disulphide with HO• firstly produces methyl thiosulphonate and methyl sulphenic acid, then further oxidized to generate methanesulphonic acid, and the C–S bonds in the methanesulphonic acid were broken to generate sulphuric acid and formic acid. So the oxidative degradation products of organic sulphides are sulphuric acid, formic acid and a small amount of acetic acid. [ABSTRACT FROM AUTHOR]

Printed electronics (PE) is one of the most dynamic technologies in the world. It proposes low-cost electronic network production in flexible substrates by numerous printing techniques, (screen printing, gravure, offset, flexographic, and inkjet printing), used in various industries. In PE, ink pigments are replaced by metallic particles or precursors that transmit electrical conductivity to the printed patterns such as carbon, polymers and conductive pigments. Conductive inks play an important role in printed electronics, and despite the number of conductive ink types available on the market, there are still issues to be addressed. Some of these restrictions include the use of toxic chemical reagents and solvents and complicated manufacturing protocols, which often make the industrialization of conductive inks an even more distant goal. In particular, conductive inks based on silver nanoparticles, Graphene and PEDOT:PSS are widely studied thanks to their high electrical conductivity. On the other hand, there is still work to be done to show the interest of inks based on phthalocyanine pigments, in particular copper phthalocyanine. Nevertheless, problems related to stability, dispersion and annealing temperature often limit the application of these four types of fillers. In this review, we present general information on available conductive fillers used for the formulation of conductive inks, focusing on metallic particles, carbon fillers, pigments and polymers. The influence and technical requirements of the regularly used printing techniques, as well as the post-processing treatments to achieve the targeted performance in the obtained inks have been discussed. In addition, the surface characteristics of the various types of extensible and flexible substrates used in portable electronics are described. Moreover, some types of printed flexible electronic components as well as notable applications of electronic textiles in various sectors are exhibited. Next, the major challenges for the manufacturing of printed flexible electronics and recommendations for future research are discussed in this review [ABSTRACT FROM AUTHOR]

Aerosol jet printing is an alternative to inkjet printing, the currently most established fabrication technique for printed electronics, with the benefits of small feature sizes, more homogeneous thickness of the printed layers, and the possibility to print on 3D structures. Printers are available on the market, in which the aerosol is generated outside of the print heads, with the disadvantage that only continuous operation is possible due to the long distance between atomization unit and print head. We report on the development and validation of a new integrated principle, with the atomization of the ink directly inside the print head. This enables a compact design, printing in all spatial directions and jet-on-demand operation. Based on fluid dynamic simulations, an optimized integrated print head design was developed, and fabricated. First tests have been performed in a preliminary laboratory test setup. The successful focusing of the aerosol to approximately 1/7 of the spread of the non-focused aerosol spray was validated in experiments, thus confirming the operating principle of the new aerosol-on-demand print head. [ABSTRACT FROM AUTHOR]

Previous studies on UV-curable elastomer for digital light processing (DLP) 3D printing flexible electronics mostly focused on higher stretchability and healability, thereby ignoring rapid recoverability after a stretch which is very important for the real-time transmission of electrical signals in flexible electronics. Herein, a UV-curable elastomer is developed with a novel dynamic hierarchical crosslinking network that can be stretched up to over 800% and rapid recoverability at 300% strain. We proposed a hydrogel-elastomer assembling process to simplify the manufacturing process for stretchable conductors. The stretchable conductors served as a strain sensor exhibiting excellent stability and repeatability after 10 cycles at 20–50% strain with low signal drift and hysteresis, Moreover, the strain sensor can be utilised in recognising the different bending angles of the finger, making DLP printing of conductive elastomer a viable strategy for the rapid manufacturing of flexible electronics. [ABSTRACT FROM AUTHOR]

This study reports a simple approach to prepare a nano-TiO2-Sb-Ni yellow ink-jet ink. Yellow pigments, in terms of their morphology and color appearance, were synthesized by changing Ni/Sb molar ratios and calcination temperatures. Moreover, the particle size of optimal nano-TiO2-Sb-Ni pigment controlled by CTAB and PVP in a co-precipitation process. TGA, spectrophotometry, and XRD were used to characterize the prepared nano-TiO2-Sb-Ni pigments. SEM and TEM were used to investigate the morphology and size of the prepared nano-pigments, respectively. Finally, the synthesized spherical nano-pigment had an average diameter of 65 nm was well dispersed in water. A general ink-jet printer printed the stable, homogenous nano-ceramic ink. Ultimately, the more yellow appearance could be obtained through increasing the number of printing runs. [ABSTRACT FROM AUTHOR]

Anionic surfactants are important components of many products used in everyday life in all households. They are also applied in various industrial fields at a very large scale. Since they have a negative influence on the environment, it is an imperative to monitor their concentration in aquatic ecosystems. Therefore, it is of great importance to develop new methods for the determination of a wide spectra of anionic surfactants in complex environmental samples in a short time. A comprehensive review of potentiometric sensors for the determination of anionic surfactants in the last 50 years is given with special concern to papers published since 2000, but noting some earlier published important papers. The latest development in use of new ionophores, polymer formulations, and nanomaterials is presented. Additionally, the application of new potentiometric sensors in batch mode or in miniaturized microfluidic methods is discussed. [ABSTRACT FROM AUTHOR]

Hydrogen sulfide (nH2S) and sulfur oxide (SOn; n = 1, 2, 3) gases in early Earth's globally anoxic atmosphere were subjected to gas-phase chemical transformations by UV light. A principal photolysis pathway at that time produced elemental sulfur aerosols with mass-independently fractionated (MIF) isotopic values carrying variable minor isotope (33S, 36S) compositions. These rained into the sulfate-deficient Archean (ca. 3.85–2.5 Ga) oceans to react with [Fe2+]aq and form sedimentary sulfides. The MIF-bearing sulfides were incorporated into Archean sediments, including banded iron formations (BIF). Such aerosols may also have fueled microbial sulfur metabolisms, and thus are traceable by the MIF sulfur isotopes. Yet, data show that before ∼3.5 Ga mass-dependent34S/32S values in Early Archean sediments tend to fall within a narrow (±0.1%) range even as they carry mass-independent values. By about 3.5 Ga, 34S/32S values show much greater changes (>1%) in range congruent with microbial metabolic processing. Here, we trace probable pathways of elemental sulfur aerosols into Archean sediments, and couple our study with analysis of the evolutionary relationships of enzymes involved in sulfur metabolism to explain the observed trends. Our model explains why elemental sulfur aerosols were apparently not utilized by the Eoarchean (pre-3.65 Ga) biosphere even though an immediate precursor to the required enzyme may have already been present. Evolution of microbial sulfur metabolisms is tracked by multiple sulfur isotopes Alkaline hydrothermal vents were an abode for early microbial life Sulfite detoxification prompted anaerobic respiration Reversal of respiratory electron transport chain (ETC) stimulated photothiotrophy Surplus e- acceptors permitted the emergence of elemental sulfur reduction [ABSTRACT FROM AUTHOR]

Dissimilatory iron reduction and sulfate reduction are the most important processes for anaerobic mineralization of organic carbon in marine sediments. The thermodynamics and kinetics of microbial Fe(III) reduction depend on the characteristics of the Fe(III) minerals, which influence the potential of Fe(III)-reducers to compete with sulfate-reducers for common organic substrates. In the present study, we tested different methods to quantify and characterize microbially reducible Fe(III) in sediments from a transect in Kongsfjorden, Svalbard, using different standard sequential endpoint extractions and time-course extractions with either ascorbate or a Fe(III)-reducing microbial culture. Similar trends of increasing 'reactive Fe' content of the sediment along the fjord transect were found using the different extraction methods. However, the total amount of 'reactive Fe' extracted differed between the methods, due to different Fe dissolution mechanisms and different targeted Fe fractions. Time-course extractions additionally provided information on the reactivity and heterogeneity of the extracted Fe(III) minerals, which also impact the favorability for microbial reduction. Our results show which fractions of the existing Fe extraction protocols should be considered 'reactive' in the sense of being favorable for microbial Fe(III) reduction, which is important in studies on early diagenesis in marine sediments. [ABSTRACT FROM AUTHOR]

In this work, the quinone based 3,3′,5,5′-tetra-tert-butyl-4,4′-stilbenequinone was tested as a catalyst in the sulfide oxidation in aqueous medium. On the basis of the obtained experimental results, the catalytic cycle of sulfide oxidation in the presence of stilbenequinone has been established. The research results also point out that a considerable amount of hydrogen peroxide is formed during catalyst regeneration. Application of the catalyst based on stilbenequinone was made to industrial wastewater treatments. According to Fenton reaction, a new catalytic system composed of ferrous iron and stillbenequinone has been developed for the sulfide oxidation. [ABSTRACT FROM AUTHOR]

Carbon composites have been synthesized by a simple two-stage method that includes impregnation of a cellulose matrix with a copper salt and its pyrolysis. The effects of ammonium stearate, temperature and pyrolysis conditions on the composites morphology have been studied. The approach represented in this work is a simple method of targeted regulation and control of the morphology, specific surface area and porosity of a carbon composite. [ABSTRACT FROM AUTHOR]

Liquid-phase exfoliated graphene sheets are promising candidates for printing electronics. Here, a high-performance printed 2.4 GHz graphene-based antenna is reported. Graphene conductive ink prepared by using liquid-phase exfoliation process is printed onto a water-transferable paper by using blade printing technique, which is then patterned as dipole antenna and transferred onto a target substrate. The fabricated dipole antenna (43 × 3 mm), exhibiting typical radiation patterns of an ideal dipole antenna, achieves −10 dB bandwidth of 8.9% and a maximum gain of 0.7 dBi. The printed graphene-antennas satisfy the application requirements of the Internet of Things and suggest its feasibility of replacing conventional metallic antennas in those applications. [ABSTRACT FROM AUTHOR]

The reaction of [RuIII(EDTA)(H2O/OH)]−/2− (EDTA4− = ethylenediaminetetraacetate) with bisulfide (HS−) and persulfide (HSS−) leading to the formation of a dinuclear disulfur-bridged [(EDTA)RuIIISSRuIII(EDTA)]4− product has been studied spectrophotometrically. Kinetics of the reaction of [RuIII(EDTA)(H2O/OH)]−/2− with HS− was studied in aqueous solution as a function of [HS-] at a constant pH of 8.2 (phosphate buffer) and temperature (20 °C). Formation of the product complex, [(EDTA)RuIIISSRuIII(EDTA)]4−, in the reaction of [RuIII(EDTA)(H2O/OH)]−/2− with HSS− was identified by ESI-MS studies. A working mechanism in agreement with the spectroscopic and kinetic data is presented. [ABSTRACT FROM AUTHOR]

Nitrate contamination is a risk to human health and may cause eutrophication, whereas H2S is an undesirable constituent in biogas. In order to better understand denitrification using gaseous H2S as electron donor, this study investigated denitrification at different molar ratios of sulfur and nitrogen (S/N ratios) and H2S dosages. Although nitrate continued to decrease, a lag in sulfate generation was observed, implying the generation of sulfide oxidizing intermediates, which accumulated even though nitrate was in excess at lower S/N ratios of 0.19 and 0.38. More addition of H2S could result in a longer lag of sulfate generation. Before depletion of dissolved sulfide, denitrification could proceed with little nitrite accumulation. High throughout sequencing analysis identified two major genera, Thiobacillus and Sulfurimonas, that were responsible for autotrophic denitrification. The simultaneous removal of nitrate and H2S using a wide range of concentrations could be achieved. [ABSTRACT FROM AUTHOR]

This paper presents the improved method of analysis and evaluation of the silver layers' adhesion printed by inkjet printing technology. The generally known method for adhesion measurement of layers and coatings according to the standards ASTM D3359 and ISO 2409 has been improved by development of the automatic evaluation software of achieved results from cross cut tests. The developed evaluation tool offers the possibilities of calculation the detached area, rotation of the image, setting the threshold and the automatic classification according to the mentioned standards. The inaccuracy caused by samples' assessment by humans is mainly eliminated by using of this tool. The developed evaluation tool has been applied to experimental works oriented to analysis of the adhesion of two commercially available silver based nano-inks on two polymeric based substrates (PI and PET). For this purpose, different sintering conditions have been applied to analysed samples. The achieved results show the differences between the investigated nano-inks' adhesion on two types of polymeric substrates. The adhesion of silver layers can be optimized by controlling the sintering conditions. By developing the software tool the simple and inaccurate method of adhesion analysis has been upgraded to the appropriate technique to the silver layers' adhesion testing. The improved method for adhesion measurements can serve as a tool for fast and relatively simple technique for technologist. [ABSTRACT FROM AUTHOR]

Dry foam formulation technology is alternative approach to enhance dissolution of the drug. Sildenafil citrate was suspended in sodium dodecyl sulfate solution and adding a mixture of maltodextrin and mannitol as diluent to form a paste. Sildenafil citrate paste was passed through a nozzle spray bottle to obtain smooth foam. The homogeneous foam was dried in a vacuum oven and sieved to obtain dry foam granules. The granules were mixed with croscarmellose sodium, magnesium stearate and compressed into tablet. All formulations were evaluated for their physicochemical properties and dissolution profiles. All the tested excipients were compatible with sildenafil citrate by both differential scanning calorimetry (DSC) and infrared (IR) analysis. There are no X-ray diffraction (XRD) peaks representing crystals of sildenafil citrate observed form dry foam formulations. The hardness of tablets was about 5 kg, friability test <1% with a disintegration time <5 min. The sildenafil citrate dry foam tablet had higher dissolution rate in 0.1 N HCl in comparison with commercial sildenafil citrate tablet, sildenafil citrate prepared by direct compression and wet granulation method. Sildenafil citrate dry foam tablet with the high-level composition of surfactant, water and diluent showed enhanced dissolution rate than that of the lower-level composition of these excipients. This formulation was stable under accelerated conditions for at least 6 months. [ABSTRACT FROM AUTHOR]

In this research, the spark discharge method (SDM) was used for in-situ synthesis of copper and copper oxide nanoparticles (NPs) on cotton fabrics for producing antibacterial textile. Varieties of analytical techniques were applied for the characterization of both NPs and synthesized CuO NPs on cotton fabrics. The structural characterization of the particles was carried out by the X-ray powder diffraction method. Also, the morphological properties of treated cotton samples were investigated using scanning electron microscope. Particle size and size distribution were measured by dynamic light scattering apparatus. The results show that concentration of 100 ppm is enough for killing 106 CFU/mL of bacteria. It is indicated that the synthesized CuO NPs are very strong against both Staphylococcus aureus and Escherichia coli. Also, the durability of antibacterial efficiency after 15 times of washing was tested. The results confirm that the antibacterial fastness properties are significant and no colonies spread over agar plate after 15 cycles of washing. It was concluded that SDM for in-situ synthesize of nano-CuO on cotton fabrics in batch systems is very promising method. [ABSTRACT FROM AUTHOR]

Copper is an inexpensive replacement for silver in electronic applications such as solar cell metallization, electromagnetic interference packaging, and printable electronics. However, copper has a characteristically low reduction potential under ambient conditions, favoring formation of non-conducting copper oxides. Here, a spray pyrolysis method of producing oxidation resistant copper particles with surfaces rich in zinc, without need for post-fabrication modifications is described. The effects of precursor and reactor parameters on the particle surface composition with respect to the bulk composition are explored. At reactor temperature conditions of 1000 °C with a precursor containing 90 at% copper-10 at% zinc, the formation of desired morphologies was achieved, smooth dense particles with surfaces enriched in zinc. Increasing the concentration of zinc in the precursor did not improve enrichment, and instead led to the formation of a zinc diamine chloride [Zn(NH3)2Cl2] byproduct. © 2018 American Association for Aerosol Research [ABSTRACT FROM AUTHOR]

A set of protein-stabilised emulsions at pH 7.0, pH 6.0, and pH 5.0, and their counterpart surfactant emulsions, was designed with near-identical droplet size distribution and phase volume to study the specific contribution of hydrodynamic and pair potential interactions to the interfacial mechanisms of these emulsions systems. In this way, further the interfacial layer of these creaming emulsions to enhance perceived fat content could be manipulated. Creaming behaviour, surface shear, and bulk rheological measurements were performed. This work reflects the great importance of local pair potential in the formation of a highly viscoelastic interfacial film, which could be manipulated changing the surface charge of the protein to develop a well-packed cream layer in the protein-stabilised emulsions. [ABSTRACT FROM AUTHOR]

Current paper focuses on the development and characterization of flexible antenna based on conductive metal pattern on polyester fabric. The flexible fabric patch antenna was prepared by printing of metallic patterns on fabric textures through a multi-step process. The inkjet printing followed by electroless nickel plating methods were employed to coat different patch sizes and shapes with extremely high conductivity on insulated fabric. The scanning electron micrograph imaging technique confirms the formation of Ni nanoparticle with normal distribution and average size of 150 ± 20 nm. The EDAX analysis reveals more than 93%w/w Ni which supports the high four-point probe conductivity of 2500 ± 175 S/cm for antenna patterns. The X-ray diffraction pattern also indicates the amorphous nickel formation and randomly phosphorus atoms trapped between the nickel atoms. Also, the measured results evidence that the tensile strength of the textile Antenna shows an increase of 25.72% in the warp direction and 19.98% in the weft direction. Also the amount of flexural stiffness significantly improves and the wrinkles reduced after electroless plating. Also the antenna’s gain and bandwidth were studied by spectrum analyzer and the coated film surfaces. The largest printed patch antenna experienced a significant increase of about 1 kHz in bandwidth and −3 dB increase in gain value compared to other antennas. Also, the rectangular shape antenna showed a peak value at bandwidth of 4.2 kHz and gain value of −0.1 dB in comparison with spiral antenna. [ABSTRACT FROM AUTHOR]

The purpose of this study was to investigate the effects of titania addition on adhesion strength of silver colloids to glass substrate. Our results indicated that when the pH was adjusted to 10, the mixed slurry of titania and silver colloids was stable with no sign of settling at approximately 4 hr. After film deposition by doctor blade method and subsequent sintering treatment, the adhesion strength between silver film and glass substrate was measured by both ASTM D3359 and D4541 standards. The results showed positive correlation of adhesion strength to both the titania concentration and sintering temperature. The adhesion strength reached 7.0 MPa when we added 8 wt% titania (based on silver) and sintered the film at 320°C for 20 min. X-ray photoelectron spectroscopy data revealed that interdiffusion of Ti into both glass substrate and silver colloid might be responsible for adhesion enhancement. On the other hand, the electrical resistivity of films increased with titania addition. This fact implied that we need to compromise between these two properties when titania addition was used to improve adhesion between silver colloid and glass substrate. An empirical model was subsequently proposed to simulate the compromise between adhesion strength and electrical resistivity. [ABSTRACT FROM PUBLISHER]

Cu-Sn binary particles were generated via spray pyrolysis from metal salt precursors with ethylene glycol as the co-solvent and reducing agent. The morphology, crystallinity, and elemental distribution of particles were tunable by changing the reaction temperature, residence time, and quench gas flow rate. Hollow porous particles were fabricated with a higher Sn concentration on the particle surface when the furnace set point was 500°C, while solid particles with a lower surface Sn concentration were generated when the furnace set point was 1000°C. Particles with spherical morphologies were obtained at long residence time conditions (4.5 s). Cu-Sn binary particles with irregular structures (e.g., pores on the particle surface, fragmented spherical particles, and lamellar fragments) were formed at short residence time conditions (0.92 s). A possible spray pyrolysis mechanism was proposed that incorporates chemical reaction steps and structural progression. By this mechanism, the metal salts are believed to sequentially undergo hydrolysis to metal hydroxides, decomposition to metal oxides, reduction to metals, and finally diffusion of Sn into the Cu matrix to generate the Cu-Sn solid solution. Copyright © 2017 American Association for Aerosol Research [ABSTRACT FROM PUBLISHER]

Protection and esthetics are the two common characteristics typically associated with textiles as clothing. Nevertheless, with the quickly altering needs of today’s consumers, a third characteristic is rising – that of “intelligence” – that is being integrated into fabrics to produce interactive or textiles (or i-textiles). The term electronic textiles, or e-textiles, are used to denote the class of fabric structures that integrate electronic elements with textiles and can sense changes in its environment and respond to it. This new class of wearable electronic systems is being designed to meet new and innovative applications in the military, public safety, healthcare, space exploration, sports, and consumer fitness fields. The goal of this paper is to focus on recent advances in the field of Smart Textiles and pay particular attention to the materials and their manufacturing process. Each technique shows advantages and disadvantages and the aim of this study is to improve the overall usability of smart clothing products by reviewing all developments which have been done in this case in order to straighten the path for future investigations and researches in this field. [ABSTRACT FROM AUTHOR]

The films with the extreme concentration of poly (diallyldimethylammonium chloride)/sodium dodecylsulfate complex spread to the surface of aqueous solutions of formic and acetic acids reduce the evaporation rate of liquids by 3–6% and demonstrate selective properties increasing water content in the vapor by 1–3 abs.%. The concentrations of solutions were up to 30 vol.%. The formation conditions of such films were determined by means of the Wilhelmy plate technique. Surface tension isotherms of aqueous solutions of acids were also obtained. [ABSTRACT FROM AUTHOR]

Sulfur and oxygen isotope fractionation of elemental sulfur disproportionation at anaerobic haloalkaline conditions was evaluated for the first time. Isotope enrichment factors of the strains Desulfurivibrio alkaliphilus and Dethiobacter alkaliphilus growing at pH 9 or 10 were −0.9‰ to −1‰ for sulfide (34ϵ), +3.6‰ to +4.7‰ for sulfate (34ϵ), and +3.5‰ to +7.7‰ for oxygen in sulfate (18ϵ). These values are significantly smaller compared to previously published values of sulfur disproportionators at neutral pH. We propose that this discrepancy is caused by masking effects due to preferential formation of polysulfides at high pH leading to accelerated internal sulfur turnover rates, but cannot rule out distinct isotope effects due to specific enzymatic disproportionation reactions under haloalkaline conditions. The results imply that the microbial sulfur cycle in haloalkaline environments is characterized by specific stable sulfur and oxygen isotope patterns. [ABSTRACT FROM AUTHOR]

Glucose-responsive monoolein (MO) cubic phase was prepared by immobilizing proteinoid composed of Asp and Leu (PAL) and hydrophobically modified glucose oxidase (HmGOD) onto the MO bilayers. The hydrodynamic mean diameter of PAL aggregate in aqueous solution decreased with increasing the pH value. The number of pamitic acid residue per one molecule of HmGOD was determined to be 6.3 by a calorimetric method. HmGOD could acidify glucose solution in a few hours, possibly because it converted glucose to gluconic acid. PAL- and HmGOD-immobilized MO cubic phase was prepared by hydrating MO melt with the mixture aqueous solution of PAL and HmGOD. The cubic phase exhibited its phase transition around 62.5°C, determined by polarizing microscopy. The release of carboxylic fluorescein (CF) from the cubic phase was suppressed when the pH value of release medium decreased, possibly because PAL can aggregate more at a lower pH value. The release was suppressed when glucose concentration increased, possibly because the release medium can be more acidified and PAL will be more aggregated at a higher glucose concentration. The cubic phase could be used as a drug carrier which releases its content in a sustained manner when the glucose concentration is abnormally high. [ABSTRACT FROM PUBLISHER]

The adhesion of silver colloids to a polyimide (PI) substrate was investigated in this study. This issue would be of concern when one tried to print electronic circuits on a flexible PI substrate. To enhance the adhesion between them, the PI surface was first roughened by using the sandblasting technique, and varying degrees of roughness were achieved using various sizes of alumina particles and various air pressures for sandblasting. The adhesion strength of silver colloids to the PI substrate after sintering was then measured according to both ASTM D4541 and ASTM 3359 standards. The results indicated that adhesion strength increased proportionally with surface roughness; however, this enhancement effect was lessened when the roughness was above 880 nm. Sintering temperature was also beneficial in increasing adhesion to the substrate; however, the electrical resistance of the silver colloids after sintering also increased with the degree of roughness. This implied that the packing of silver colloids was also affected by surface roughness. Consequently, values of surface roughness were optimal when adhesion strength and electrical resistivity were balanced. [ABSTRACT FROM PUBLISHER]

Highly mineralized springs in the Scuol-Tarasp area of the Lower Engadin and in the Albula Valley near Alvaneu, Switzerland, display distinct differences with respect to the source and fate of their dissolved sulphur species. High sulphate concentrations and positive sulphur (δ34S) and oxygen (δ18O) isotopic compositions argue for the subsurface dissolution of Mesozoic evaporitic sulphate. In contrast, low sulphate concentrations and less positive or even negative δ34S and δ18O values indicate a substantial contribution of sulphate sulphur from the oxidation of sulphides in the crystalline basement rocks or the Jurassic sedimentary cover rocks. Furthermore, multiple sulphur (δ34S, Δ33S) isotopes support the identification of microbial sulphate reduction and sulphide oxidation in the subsurface, the latter is also evident through the presence of thick aggregates of sulphide-oxidizingThiothrixbacteria. [ABSTRACT FROM AUTHOR]

Solubility is an important physicochemical parameter in nanoregulation. If nanomaterial is completely soluble, then from a risk assessment point of view, its disposal can be treated much in the same way as “ordinary” chemicals, which will simplify testing and characterisation regimes. This review assesses potential techniques for the measurement of nanomaterial solubility and evaluates the performance against a set of analytical criteria (based on satisfying the requirements as governed by the cosmetic regulation as well as the need to quantify the concentration of free (hydrated) ions). Our findings show that no universal method exists. A complementary approach is thus recommended, to comprise an atomic spectrometry-based method in conjunction with an electrochemical (or colorimetric) method. This article shows that although some techniques are more commonly used than others, a huge research gap remains, related with the need to ensure data reliability. [ABSTRACT FROM PUBLISHER]

In this study, biological methyl mercaptide removal is investigated using the bacteriumThiobacillus thioparusin a fed batch bioreactor. In this process, methyl mercaptide is converted into elemental sulfur particles as an intermediate in the oxidation of methyl mercaptide to sulfate. The main product is sulfur at either low dissolved oxygen or high methyl mercaptide concentrations, and also more sulfates are produced at high dissolved oxygen. According to the reactions performed, a mathematical model is developed. The model parameters are estimated and the model is validated by comparison to experimental data. The results show that the proposed model is in a good agreement with experimental data. According to the experimental results and mathematical model, sulfate and sulfur selectivity are sensitive to the concentration of dissolved oxygen. For concentrations of methyl mercaptide 0.2 mmol L−1in the bioreactor and dissolved oxygen of 0.5 ppm, only 14% of sulfide load is converted to sulfate while the figure is 60% at the same methyl mercaptide concentration and dissolved oxygen of 4.5 ppm. At high sulfide load to the bioreactor, the concentration of noneliminated methyl mercaptide increases, leading to higher sulfur particle selectivity and consequently lower sulfate selectivity. [ABSTRACT FROM AUTHOR]

Surface properties of multicomponent particles produced in spray drying can be controlled by selective accumulation of specific components, which are present in the liquid feed, on the particle surface. Such modification of the surface composition can take place only before a solid shell forms on the particle surface. In this contribution, the influence of the concentration of surface active component on modifications of the surface composition is discussed. Based on results of single-droplet drying simulations, changes in the concentration of the surface active component at the solution-air interface are related to the composition of spray-dried particles. [ABSTRACT FROM AUTHOR]

In this review, the authors investigate different methods of synthesizing antimicrobial chitosan-silver nanocomposites and divided these nanocomposites into two major groups on the basis of metallic or ionic nature of silver. Chitosan-metallic silver composites were prepared by following different techniques: chemical, thermal, radiation (gamma ray or UV), and electrochemical. However, the polymeric nature of chitosan allows formation of complexes with silver ions. Their antimicrobial efficacy was evaluated by the disc diffusion method. The authors compare antimicrobial efficacy of all these materials based on the findings of various research groups to come up with a strategy for synthesizing chitosan-silver nanocomposites to target a specific pathogen. [ABSTRACT FROM AUTHOR]

Silver, bismuth, and bismuth-silver nanoparticles were synthesized and characterized by cyclic voltammetry, electrochemical impedance spectroscopy, ultraviolet-visible spectroscopy, infrared spectroscopy, Raman spectroscopy, and transmission electron microscopy to determine the electrochemical, optical, structural, and morphological properties of the nanomaterials. The silver, bismuth, and bismuth-silver nanoparticles were shown to have an average particle size of 10–30 nanometers by microscopy. The electrochemical results showed that the bismuth-silver nanoparticles exhibited good electrocatalytic activity that can be harnessed for sensor construction and related applications. The ultraviolet-visible, infrared, and Raman spectroscopy results confirmed the structural properties of the bismuth-silver nanoparticles. In addition, the microscopy and electron diffraction morphological characterization confirmed the nature of the bismuth-silver nanoparticles. [ABSTRACT FROM PUBLISHER]

Inkjet deposition can be a complementary technology to laser ablation to enable new processes. One such process is the One step interconnect for thin film photovoltaics, which is an improved method for series interconnection. The standard series interconnection process consists of three laser scribes between the deposition of the three key cell layers; transparent front contact, absorber layer and the metallic back contact. The one step interconnect allows the series interconnection to occur after the deposition of all layers significantly simplifying the manufacturing process. This is achieved by inkjet printing of conductive and insulative materials concurrently with depth selective laser scribes. The one step interconnect process has been shown to make effective interconnects on cadmium telluride photovoltaics with fill factors >60%. The benefits are many and include the reduction of capital equipment costs, reduced panel wastage and potentially improved material performance. The process is fully scalable and production ready. [ABSTRACT FROM AUTHOR]

Air stable silver nanoparticles (NPs) at a high concentration (up to 0·2M) were synthesised by the reduction in Ag+ ions with glucose in cetyltrimethylammonium bromide (CTAB) solutions, for preparing nano-Ag ink applicable for direct writing on photo paper using a gel ink pen. The reaction was performed at room temperature, and the input of extra inert gas was not necessary. The UV/vis spectrum exhibited an absorption band at 413 nm, revealing the formation of Ag NPs. By the analysis of X-ray diffraction (XRD), the resultant particles were confirmed to be pure Ag with a face centred cubic structure. From the (high resolution) TEM analysis, it was found that the mean diameter of Ag NPs was 16·5 nm, and the morphology of the particles exhibited highly crystalline nature. In addition, the excess of CTAB was effective in reducing the aggregation and size of the Ag NPs and in improving their air stability. The reduced size and enhanced air stability of the Ag NPs resulted in an improved particle density upon sintering, which was mainly responsible for the increased conductivity of the Ag patterns. The resistivity of Ag patterns sintered at 160°C for 2 h was 6·8±0·8 μΩ cm, 4·2 times the bulk resistivity. A sample paper based electrode and circuits were successfully made, and all of them exhibited excellent flexibility and good conductivity, which can be used as part of some flexible electronic devices, such as triboelectronic generator, solar cells and radio frequency identification antenna, etc. [ABSTRACT FROM AUTHOR]

We report production of bimetallic nanostructured copper– silver coatings byin situdeposition and sintering of metal nanoparticles produced as an aerosol. The metal nanoparticles themselves have potential applications in printed electronics, catalysis, antibacterial coatings, and heat transfer fluids. In many applications, nanoparticles are dispersed in an ink, which is then printed or coated onto a substrate and converted into a nanostructured thin film. Direct deposition from the aerosol allows us to produce nanostructured thin films without first dispersing the particles in a solvent. The high temperature reducing jet process allows formation of these metal nanoparticles from low-cost metal salt precursors in the gas phase. In this method, a fuel-rich hydrogen flame provides a low-cost source of energy to drive nanoparticle formation in a reducing environment. The aqueous precursor solution is delivered into the hot combustion product gases within a converging–diverging nozzle. The high-speed gas flow atomizes the precursor and provides exceptionally rapid mixing of the precursor with the hot gases. Here, particles are formed, then immediately quenched and deposited on a glass substrate. The effect of the silver content of the mixed copper–silver films on their electrical conductivity was studied systematically, revealing an abrupt transition from low conductivity to high conductivity between 30 wt.% and 40 wt.% silver. Copyright 2013 American Association for Aerosol Research [ABSTRACT FROM AUTHOR]

Polypropylene nonwoven fabrics samples were modified using poly(2-(N,N-dimethyloamino ethyl) methacrylate) (PDAMA) and silver-containing layers. The structure of the material after modification was confirmed using scanning electron mocroscope, energy-dispersive X-ray spectroscopy, Fourier Transfer Infrared Spectroscopy (FTIR), and electro-kinetic measurements. It was found that samples with external PDAMA layers have excellent activity against Staphylococcus aureus under dynamic contact conditions. In contrast, samples finished with deposited silver showed little antimicrobial effect. Antibacterial tests conducted under static conditions showed no antibacterial activity irrespective of the deposited layers. [ABSTRACT FROM AUTHOR]

The association of poly (diallyldimethylammonium) chloride (PDDAC) hydrophobically modified with octyl, decyl, and dodecyl chlorides, with 4-n-alkylbenzene sulfonates, was studied in aqueous solution by ultrafiltration. Experimental data agree well with the Hill's equation for the association process. The association degree increases with the size of the sulfonate anion and decreases as the polyelectrolyte side chains length increases. This kind of polyelectrolyte is able to form hydrophobic microdomains lowering the availability of association sites due to a hypercoiling process. The association process was, in all cases, cooperative, having a maximum with the octyl derivative. The association degrees were significantly higher than those found with PDDAC itself. The standard free-energy contribution to the association process was between −19 and −20 kJ/mol of benzene sulfonate. These values are comparable with those recently found for a family of hydrophobic cationic polyelectrolytes at the water/chloroform interface. Therefore, in terms of the association process, it does not matter if the polyelectrolyte is adsorbed at a liquid/liquid interface or if it is soluble in a pure phase. The contribution of the methylene groups was very small, ranging from −0.20 to −0.50 kJ/mol. This reveals that the main interaction governing the association is the aromatic ring–ammonium group interaction. [ABSTRACT FROM PUBLISHER]

Hydrophobic aluminum nanoflake slurries were freeze dried using varying freezing conditions, aluminum concentrations, and shelf temperatures. The effectiveness of using cyclohexane as a carrier to produce dry, de-agglomerated aluminum powders was determined from light scattering measurements. Significantly less aggregation was observed in the dried aluminum powders when cyclohexane was used as opposed to water, with most aggregation being prevented by freeze drying dilute aluminum slurries at low shelf temperatures. A significant increase in the primary rate of freeze drying was also observed when particles were dried from cyclohexane compared to particles dried from water. [ABSTRACT FROM PUBLISHER]

Diallyl disulfide reacts within minutes with liquid sulfur at 120°C giving a family of diallyl polysulfanes, All2Sn(n=3–22), characterized by ultra-performance liquid chromatography-(Ag+)-coordination ion spray-mass spectrometry (UPLC-(Ag+)CIS-MS). Similarly, garlic oil (GO), bis-(2-methyl-2-propenyl), bis-(2-chloro-2-propenyl), bis-(3-methyl-2-butenyl), and bis-(2-cyclohexen-1-yl) disulfides all give families of polysulfanes with up to 22 sequential sulfur atoms. New members of families of silver chelators with up to 10 sulfur atoms were found in GO using UPLC-(Ag+)CIS-MS. [ABSTRACT FROM PUBLISHER]

In this work, the biogeochemistry of marine sediments from the Kiel Bight, coastal SW Baltic Sea, is studied based on the abundance and isotopic composition of organic carbon and different forms of sedimentary sulphur. Active bacterial sulphate reduction, partly under sulphate-limiting conditions, is evident from paired δ34S and δ18O values of pore water sulphate. The resulting pore water sulphide is partly precipitated as acid-volatile iron sulphide and subsequently forms sedimentary pyrite, partly serves in later diagenetic sulphurisation of organic matter, or remains dissolved in the pore water, all evident from the respective δ34S values. Microbial sulphate turnover is associated with an apparent isotopic fractionation between dissolved sulphate and dissolved sulphide (Δ34S) that varies between 46 and 66‰. [ABSTRACT FROM AUTHOR]