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The essential use concept aims to better protect consumers, vulnerable groups, and the environment from the most harmful chemicals by phasing out uses considered non-essential for society. Given the lack of empirical research evaluating this novel approach for chemical management in real-world settings, the aims of the present analysis were to 1) investigate if the information provided in applications for authorisation under REACH allowed for the identification of non-essential uses of substances of very high concern (SVHCs), and 2) identify data gaps, challenges and potential needs for revising the assessment criteria to effectively implement the essential use concept in the REACH authorisation. In total, 100 uses covering 11 SVHCs were analysed. 4-(1,1,3,3-tetramethylbutyl) phenol (OPnEO) and chromium trioxide were among the most frequently used substances, covering 42% and 35% of the analysed uses. Using the current essential use criteria, 55% of all analysed uses were categorised as essential, while 10% were categorised as non-essential. Potentially, authorisations would not have been granted for the identified non-essential uses under REACH if the concept had been implemented at the time. However, for 35% of the uses it was not possible to assess their essentiality and these uses were therefore categorised as "complex." These challenges were due to the multiple purposes of the technical function, lack of detailed information on the spectrum of end-uses, and difficulties in interpreting the essential use criteria. Consequently, for a successful implementation of the essential use concept, we recommend the European Commission to develop guidance for applicants and refine the essential use criteria to ensure a transparent and resource-efficient authorisation procedure under REACH. [ABSTRACT FROM AUTHOR]

Deoxidation via chemical etch is an important step in the pretreatment of aluminium alloy chemical oxidation. Typically, the chemical deoxidation of aluminium alloy is carried out in triacid solution that contains chromic anhydride. While the use of Cr (VI) in triacid solution can cause severe chemical contamination. In this paper, we have developed a Cr-free solution for deoxidation, iron sulphate and etch inhibitors are selected to replace Cr (VI). The formula of deoxidation solution was optimised through the combination of single-factor method and Box-Behnken method. The results show that the Cr-free deoxidation solution we proposed shows a deoxidation effect comparable to that of a triacid solution. [ABSTRACT FROM AUTHOR]

Background Galidesivir (GDV) is a promising new antiviral drug for the potent and safe treatment of a broad spectrum of viral diseases, including COVID-19. In the literature, no analytical method exists for the determination of GDV in bulk and dosage form. Objective The aim of this study was the development of versatile green and simple microwell spectrophotometric methods (MW-SPMs) for the determination of GDV in its bulk form and capsules. Methods Three MW-SPMs were developed involving the oxidation of GDV by ammonium metavanadate (AMV), chromium trioxide (CTO), and potassium iodate (PIO) in an acid medium. The reactions were carried out in 96-well plates at room temperature and the absorbances of chromogenic reaction products were measured by an absorbance microplate reader at 780, 595, and 475 nm for AMV, CTO, and PIO, respectively. Variables influencing the reactions were carefully investigated and optimized. Results Linear relations with excellent correlation coefficients (0.9991–0.9997) were found between the absorbances and GDV concentrations in the range of 25–500 µg/mL. The LODs were ≥8.3 µg/mL. The accuracy and precision of the three MW-SPMs were confirmed by recovery and replicate analysis, respectively. The recovery values were 98.6–101.2% and the RSDs were ≤1.02%. The proposed MW-SPMs were successfully applied to the analysis of GDV in bulk drug and capsules with high accuracy and precision. The greenness of the MW-SPMs was confirmed by three comprehensive metric tools. Conclusion The proposed MW-SPMs combined the inherent advantages of microwell-based analysis and the use of common laboratory reagents for the reactions involved. These advantages include high-throughput, ready automation, reduced sample/reagent volume, precise measurements, and versatility. The advantages of the use of common laboratory reagents include availability, consistency, compatibility, safety, and cost-effectiveness. Highlights Overall, the proposed MW-SPMs are versatile valuable tools for the quantitation of GDV during its pharmaceutical manufacturing. [ABSTRACT FROM AUTHOR]

Lithium ion copper foil is prone to oxidation and discoloration on the surface during production, storage-transportation, and use, which directly affects the product yield, reliability, service life and adhesion of lithium batteries. This requires copper foil to have good anti oxidation performance. In this paper, the changes in surface morphology and oxygen content of the copper foil under different soaking and micro electroplating process conditions were studied using characterization methods such as SEM and ED AX. The impact of soaking and micro plating processes on the surface of copper foil surface anti oxidation performance. The results show that when the current density is 5 A/dm², the plating time is 10 s, the chromic anhydride concentration is 0. 5 g/L, and the glucose concentration is 1. 5 g/L. After the copper foil is baked at high temperature, there is no discoloration on the surface, and the anti oxidant performance is better. [ABSTRACT FROM AUTHOR]

In this study, we investigated the concurrent elimination of two distinct contaminants: organic matter in the form of dexamethasone phosphate (DexP) and an inorganic substance, chromium (Cr), employing UV irradiation. UV irradiation serves as a potent tool for breaking down organic materials, leading to the production of benign by-products, namely CO2 and H2O. Under optimal conditions characterized by a 30:1 DexP/Cr molar ratio and a pH level of 9, remarkable removal efficiencies were attained. In a mere 20 min, approximately 100% of DexP and 82.73% of Cr were effectively removed. Intriguingly, the removal of Cr exhibited an initially sluggish rate, with deposition commencing only after the breakdown of the DexP structure. This transformation was accompanied by the emergence of various sludge forms, each possessing unique characteristics. Utilizing Fourier-transform infrared (FTIR) analysis, we identified these sludge forms as chromium(III) hydroxide (green sludge), chromium(III) hydroxide (brown sludge), chromium(III) oxide (tiny green crystals), chromium(II) acetate chromium trioxide (red brick), and chromium oxide (black sludge). Further experimentation with varying concentrations of Cr and DexP, ranging from 50 to 150 mg L−1, yielded a range of rate constants (kobs) from 0.33 to 0.15 and removal efficiencies (robs) from 16.8 to 23.4% in the UV/DexP/Cr process. Energy efficiency output (EEO) calculations revealed that Cr precipitation ranged from 24.65 to 5.74 kW h m−3, whereas DexP EEO ranged from 12.54 to 4.73 kW h m−3. Of significant importance is the observation that when these two contaminants are removed simultaneously, the overall energy consumption is substantially lower compared to the scenario where pollutants are addressed individually. This finding underscores the efficiency and potential energy cost savings achievable through the concurrent removal of DexP and Cr using UV irradiation, making it a promising approach for environmental remediation. [ABSTRACT FROM AUTHOR]

Demonstration of glycogen in tissue holds considerable diagnostic relevance across various pathological conditions, particularly in certain tumors. The histochemical staining of glycogen using methods utilizing Schiff's reagents is subject to influences arising from the type of fixative, fixation temperature, and oxidizing agents employed. This study aimed to assess diverse fixatives, fixation temperatures, and oxidizing agents, each with variable treatment durations, in conjunction with Schiff's reagent for optimal glycogen demonstration. Paraffin blocks derived from a rabbit's liver served as the experimental substrate, encompassing 340 paraffin sections subjected to different procedures. For tissues fixed at 4 °C, good staining outcomes, as determined by the periodic acid–Schiff (PAS) stain, were observed with 10% neutral buffered formalin (NBF), 80% alcohol, and Bouin's solution. Tissues fixed at room temperature (RT) demonstrated good PAS staining results with both 10% NBF and 80% alcohol. Notably, other oxidizing agents exhibited poor outcomes across all fixatives and fixation temperature, with two exceptions, as satisfactory staining results were obtained when using 5% chromic acid. Consequently, Both 10% NBF and 80% emerge as preferred fixatives of choice for glycogen demonstration when coupled with PAS stain. It is noteworthy that Bouin's solution could also provide good outcomes when fixation occurred at 4 °C. [ABSTRACT FROM AUTHOR]

Polymer nanocomposite specimens were fabricated using the solution casting technique. The specimens were composed of a polymer blend consisting of polyvinyl alcohol (PVA) and carboxymethyl cellulose (CMC) as the organic host matrix with varying concentrations of chromium trioxide (Cr2O3) and silicon dioxide (SiO2) (ranging from 0 to 8 weight percent). The present study examined the morphological, structural, optical, and antimicrobial characteristics of PVA–CMC–SiO2–Cr2O3 nanocomposites (NCs). The X-ray diffraction analysis demonstrated the amorphous characteristics of the blend of PVA and CMC. Additionally, the intensity of the characteristic peak of the original polymers in the nanocomposite was observed to decrease significantly with an increase in the filler level. The results obtained from SEM measurements indicate a satisfactory distribution and uniformity in surface morphology. The optical microscope images indicate that the distribution of nanoparticles in the blend was uniform, resulting in the formation of a continuous network within the polymer matrix. The results of optical properties indicate that the absorbance, absorption coefficient, refractive index, dielectric constant (real and imaginary), and optical conductivity demonstrate an increasing trend with the rising concentrations of (SiO2–Cr2O3) nanoparticles, while the transmittance of the nanocomposites decreases as the concentration of nanoparticles increases. The energy band gap decreases from 4.26 to 2.91 eV and from 3.39 to 1.44 eV for allowed and forbidden transitions, respectively, with an increase in (SiO2–Cr2O3) NPs concentration. These results indicated that the (PVA–CMC–SiO2–Cr2O3) nanostructures may be considered as promising materials for optoelectronics nanodevices. The synthesized NCs underwent an antibacterial activity test using the agar disk diffusion method against two bacterial isolates, namely the gram-negative Escherichia coli and the gram-positive Staphylococcus aureus. An increase in the diameter zone was observed in the antibacterial activity index as the concentration of (SiO2–Cr2O3) nanoparticles increased. The study's findings demonstrate that the use of (SiO2–Cr2O3) nanoparticles in PVA/CMC blends resulted in heightened antibacterial properties in the samples. This indicates the potential of these nanocomposites used for various antimicrobial applications, including their potential use in the food packaging industry. [ABSTRACT FROM AUTHOR]

A gaseous elemental mercury (Hg0) sampler was developed for the assessment of mercury (Hg) pollution from the air and utilised aluminium (Al) powder as the accumulation medium. The Hg sampler is presented as an alternative cost-effective sorbent that can be used for the assessment of Hg pollution in atmospheric air in areas where natural bio-indicators such as lichens and moss do not grow, including the urban environments. The chemical treatment of Al materials was necessary to weaken the aluminium oxide (Al2O3) layer to increase the adsorption capability of Al material. Treated Al samples were exposed to Hg vapours for one hour to two weeks in a Hg atmosphere chamber. Other Al powder samples were exposed to the ambient air at areas of the Tshwane Metropolitan Municipality for six to ten months. The analysis of samples by an RA-915+ Zeeman mercury analyser showed that the limit of detection (LOD) and limit of quantification (LOQ) for the determination of Hg in Al powder with a mass of 100 mg were found to be 0.31 ng g−1 and 1.0 ng g−1, respectively. The content of Hg that accumulated on Al powder was linear from 0.1 to 25 ng g−1, thus enabling the measurement of Hg accumulation from air at the global average concentration level. Mercury from air that accumulated on Al powder in the Tshwane Metropolitan Municipality ranged between 70 ng g−1 and 155 ng g−1. [ABSTRACT FROM AUTHOR]

• Addition of CrO 3 with MgH 2 decreases the dehydrogenation temperature of MgH 2. • CrO 3 added MgH 2 also effectively interacts with Li in a Li ion battery. • Interaction between MgH 2 and CrO 3 produces Cr, MgO and MgCr 2 O 4 products. • Highly dispersed Cr nanocrystals were found, and they exhibit a size of ∼5 nm. • Interfacial activity is suggested to be crucial for the storage of both H and Li. This study explores how the chemical interaction between magnesium hydride (MgH 2) and the additive CrO 3 influences the hydrogen/lithium storage characteristics of MgH 2. We have observed that a 5 wt.% CrO 3 additive reduces the dehydrogenation activation energy of MgH 2 by 68 kJ/mol and lowers the required dehydrogenation temperature by 80 °C. CrO 3 added MgH 2 was also tested as an anode in an Li ion battery, and it is possible to deliver over 90% of the total theoretical capacity (2038 mAh/g). Evidence for improved reversibility in the battery reaction is found only after the incorporation of additives with MgH 2. In depth characterization study by X-ray diffraction (XRD) technique provides convincing evidence that the CrO 3 additive interacts with MgH 2 and produces Cr / MgO byproducts. Gibbs free energy analyses confirm the thermodynamic feasibility of conversion from MgH 2 /CrO 3 to MgO/Cr, which is well supported by the identification of Cr(0) in the powder by X ray photoelectron spectroscopy (XPS) technique. Through high resolution transmission electron microscopy (HRTEM) and energy dispersive spectroscopy (EDS) we found evidence for the presence of 5 nm size Cr nanocrystals on the surface of MgO rock salt nanoparticles. There is also convincing ground to consider that MgO rock salt accommodates Cr in the lattice. These observations support the argument that creation of active metal – metal dissolved rock salt oxide interface may be vital for improving the reactivity of MgH 2 , both for the improved storage of hydrogen and lithium. [ABSTRACT FROM AUTHOR]

Inconel 718 super alloy is suitable for components exposed to high temperatures and demanding high strength; it is one of the hardest alloys to machine by conventional processes due to its properties. Nano Powder mixed electrical discharge machining is one of the most sophisticated processes to produce precise three dimensional complicated forms of hard metals through a thermo-physical process, so it is suitable for machining Inconel 718. This study reports an experimental investigation to improve the machining performance of Inconel 718 super alloy by adding nano chromium oxide powder particles to biodegradable and renewable soybean oil, which is used as a dielectric fluid to preserve the environment, with a magnetic field to assist in improving the process performance. The effects of machining parameters, namely peak current, pulse on time, powder concentration, and magnetic field on the responses in terms of white layer thickness, heat affected zone, surface roughness, material removal rate, and surface crack density were investigated. The observed results manifested that the addition of nano chromium oxide particles to dielectric fluid enhances the process performance. The white layer thickness and heat affected zone improved by 43.93% and 48.82%, respectively. The enhancements in measured surface roughness and material removal rate were 51.76% and 20.62%, respectively. Micrographs of scanning electron microscope verifies that the number of cracks on the machined surface with 4 g/l of nano Cr2O3 powder addition was reduced by half, and surface crack density improved by 10.31%, in comparison to machining without powder addition. It is observed that the current had the largest effect on the responses, followed by powder concentration, pulse on time, and magnetic field. [ABSTRACT FROM AUTHOR]

A series of chromium trioxide/zinc metastannate (Cr 2 O 3 /ZnSnO 3) composites with different ratios were prepared via a simple two-step hydrothermal and high-temperature sintering method. The samples underwent characterization and analysis to assess their micromorphologies, elemental distributions, chemical compositions, and specific surface areas. Furthermore, gas sensing properties were evaluated through experiment. Results showed that the cubic ZnSnO 3 block in Cr 2 O 3 /ZnSnO 3 was in close contact with the surface of nanoparticulate Cr 2 O 3 and the specific surface area increases. Its primary elements are Zn, Sn, Cr, and O. The 15 wt% Cr 2 O 3 /ZnSnO 3 sensor exhibited an optimal operating temperature of 175 °C, 75 °C lower than that of pure ZnSnO 3 (250 °C). The 15 wt% Cr 2 O 3 /ZnSnO 3 sensor exhibited the best sensing performance for formaldehyde gases with a concentration of 50 ppm. It exhibited a response of 37.8 and could detect ppb-level concentrations of formaldehyde (limit of detection = 612 ppb). Additionally, Cr 2 O 3 /ZnSnO 3 showed good selectivity for formaldehyde in the presence of six gases, that is, acetone, formaldehyde, methanol, ethanol, ammonia, and carbon monoxide. Cr 2 O 3 /ZnSnO 3 exhibited good short-term repeatability and long-term stability. Because of the excellent performance of Cr 2 O 3 /ZnSnO 3 composites, they have broad application prospects in formaldehyde gas detection. [ABSTRACT FROM AUTHOR]

In this paper, we focused on the initiation of porosity in the anodic alumina under galvanostatic conditions in chromic acid, using an 18O isotope tracer. The general concept of the initiation and growth of porous anodic oxide films on metals has undergone constant development over many years. A mechanism of viscous flow of the oxide from the barrier layer to the pore walls has recently been proposed. In this work, two types of pre-formed oxide films were analysed: pure Al2O3 formed in chromic acid, and a film containing As ions formed in a sodium arsenate solution. Both were anodized in chromic acid for several different time durations. Both pre-formed films contained the oxygen isotope 18O. The locations and quantities of 18O and As were analysed by means of ion accelerator-based methods supported by transmission electron microscopy. The significant difference observed between the two oxide films is in the 18O distribution following the second step of anodization, when compared with galvanostatic anodization in phosphoric or sulfuric acid reported in previous works. From the current experiment, it is evident that a small amount of As in the pre-formed barrier layer appears to alter the ionic conductivity of the film; thus, somehow, it inhibits the movement of oxygen ions ahead of advancing pores during anodization in chromic acid. However, anodising pure alumina film under these conditions does not enhance oxygen movement within the oxide layer. In addition, the tracer stays in the outer part of the growing porous oxide film. A lower-than-expected value for pure alumina enrichment in 18O in the pre-formed films suggests, indirectly, that the pre-formed film may contain hydrogen species, as well as trapped electrons, since no Cr is detected. This may lead to the presence of space charge distribution, which has a dual effect: it both retards the ejection of Al3+ ions and prevents O2− ions from migrating inward. Thus, the negative- and positive-charge distributions might play a role in the initiation of pores via a flow mechanism. [ABSTRACT FROM AUTHOR]

Purpose: The purpose of this work was to study the effect of different wood surface preparations on the wetting and adhesion of coating. Design/methodology/approach: In this research, six different chemical preparations to evaluate the photostability and properties of wood coating. Also, the effect of the same wood treatments on the properties of the coating, i.e. wetting, adhesion and the permeability of two types of coatings, was investigated. Findings: As a result, benzoyl chloride and chromic acid were found to be the most effective photostabilizing preparations. Solvent-based polyurethane was more compatible with the prepared wood surfaces compared with water-based alkyd coatings. Research limitations/implications: Chemical modifications of wood surfaces affected the wetting of various coatings. Practical implications: Various surface properties could be changed using preparation that affects important coating properties. Social implications: Unfortunately, the properties of transparent wood coatings used outdoors disappear through the early years of use, essentially due to the wood substrate's photodegradation. Originality/value: Wood is a widespread substrate because of its comfortable handling, availability, proper cost of preparation and its good mechanical strength because of its density. Architects and designers tend to use wood in the construction of green buildings. However, this material is disposed to weathering while using outdoors and it should be solved. [ABSTRACT FROM AUTHOR]

This study investigates the synthesis of new nanocomposites (NCs) comprising polyvinyl alcohol (PVA) and carboxymethyl cellulose (CMC) with silicon dioxide (SiO2 ) and chromium trioxide (Cr2O3 ) for the use in gammarays’-shielding applications. The nanocomposites exhibit desirable properties such as low weight, elasticity, high attenuation coefficients, and costeffectiveness for gamma-rays’ shielding. The structural properties of PVA–CMC–SiO2–Cr2O3 nanocomposites are studied. The scanning electron microscopy reveals that the top surface of the PVA–CMC/SiO2–Cr2O3 NCs films exhibits uniform and cohesive aggregates or fragments distributed randomly, when the weight percentage reaches 8%. The uniform distribution of nanoparticles (NPs) in the blend is evidenced by the optical microscope images and leads to a continuous network within the polymer matrix. The study results regarding the utilization of gamma-rays’ shielding demonstrate that the nanocomposites composed of PVA–CMC/SiO2–Cr2O3 display significant attenuation coefficients for gamma rays. [ABSTRACT FROM AUTHOR]

In order to repair a failed AlSiY coating on aeroengine turbine components, the AlSiY coating was stripped using a nitric acid-based removal reagent. The homogeneity of chemical stripping was evaluated and the stripping mechanism was clarified using first-principles calculations. The effects of hydrofluoric acid (HF) and chromium trioxide (CrO3) on the homogeneity of chemical stripping were investigated by calculating the electronic work functions (EWFs) of the stripped surfaces. The results showed that the stripped surfaces of the AlSiY coating exhibited a serrated appearance when it was etched by a single nitric acid solution, indicating severely inhomogeneous stripping. With the addition of HF and/or CrO3, the homogeneity of chemical stripping could be greatly improved, which was attributed to the increased EWF of the (200) surface and the decreased EWF of the (110) surface, causing the corrosion cathode to transition from the (110) surface to the (200) surface. The HF+CrO3+HNO3 mixed reagent was the optimal combination for the uniform stripping of the AlSiY coating, while the inner layer was not broken. The Al atoms on the surface could be preferentially removed due to the strong bonding with acid ions. The research method proposed in the present work will provide a new means to design chemical removal reagents. [ABSTRACT FROM AUTHOR]

Developing efficient and stable non-noble metal catalysts for the catalytic oxidation of volatile organic compounds (VOCs) has always been key for controlling air pollution. Chromium oxide nanoparticle catalysts act as a potential material for this purpose, and their morphology has a significant impact on the catalyst performance. Herein, two types of chromium oxides with different morphologies were prepared using two different precursors in a hydrothermal route: one that was synthesized using chromic acid and exhibited a strawberry micro-spindle type morphology consisting of innumerable nanoparticles in the range of ∼20–35 nm, and the other one that was synthesized using a nitrate precursor and consisted of thoroughly dispersed nanoparticles in the range of 30–40 nm. Both of them were successfully applied for the total oxidation of toluene. The former exhibited higher efficiency; for long-term stability of the catalyst, K+ ions were added during its synthesis. Importantly, the former catalyst was superior to the latter one because of the ease of activation and migration of lattice oxygen, which was comprehensively understood using H2-TPR, O2-TPD and XPS analyses. [ABSTRACT FROM AUTHOR]

[Display omitted] The introduction of nitrogen vacancies into polymeric carbon nitride (PCN) has been attested to be a reliable strategy to enhance photocatalytic performance. Nitrogen vacancies were considered as active sites to promote the adsorption of target molecules and capture photoexcited electrons to inhibit the recombination of charge pairs, accelerate photoinduced electrons to participate in photocatalytic reaction. In this paper, a series of PCN with rich nitrogen vacancies were prepared by etching of chromic acid solution. Sample 20KCSCN had the highest photocatalytic performance whose evolution efficiency of CO 2 to CO and CH 4 can reach 3.9 and 0.5 μmol·g−1·h−1, respectively. These evolution efficiencies are 2.9 and 4 times higher than that of the PCN. Meanwhile, 20KCSCN demonstrates high CO conversion selectivity and stability. The successful introduction of nitrogen vacancies not only increases the active sites of PCN surface, but also optimizes the optical structure, which dramatically boosts the separation of photoexcited charge pairs and the reduction capacity of photogenerated electrons. The enhancement mechanism for photocatalytic CO 2 reduction performance of PCN was proposed. Besides, photocatalytic H 2 evolution experiments were performed on all samples to confirm the universality of PCN photocatalytic activity enhancement etched by chromic acid solution. H 2 evolution rate on 20KCSCN can reach 652 μmol·g−1·h−1, which is 1.6-fold higher than that on PCN (254 μmol·g−1·h−1) after 4 h irradiation under a 300 W Xe lamp. This work offers new venue for introducing nitrogen vacancies in PCN to regulate photoexcited charge pairs transfer. The photocatalytic enhancement of CO 2 reduction could be used to alleviate the serious issue of excessive CO 2 emission and energy crisis. [ABSTRACT FROM AUTHOR]

The present study investigates the characteristics of nanocomposites comprising polyvinyl alcohol (PVA), tin dioxide (SnO2), and chromium trioxide (Cr2O3) with respect to their synthesis, structural, electrical, and optical properties. Nanocomposite samples with flexibility were expeditiously synthesized using the cast method. Optical microscope (OM) images elucidated that an increase in the concentration of nanoparticles results in the formation of network pathways within the polymeric matrix, which function as charge carriers. FTIR analysis has demonstrated the existence of physical interactions between the (PVA) and the nanoparticles. The AC electrical characteristics of nanocomposites, specifically the dielectric constant and dielectric loss, exhibit a decrease as the frequency of the applied electric field increases. Conversely, an increase in concentration of SnO2/Cr2O3 nanoparticles results in an increase in these properties. AC electrical conductivity of the nanocomposites increases with both increasing frequency and concentration of SnO2/Cr2O3 NPs. Based on the analysis of its structural and electrical properties, it can be inferred that the PVA/SnO2/Cr2O3 nanocomposite exhibits potential for application in diverse electronic devices. The optical characteristics of PVA/SnO2/ Cr2O3 nanocomposites indicated that these materials exhibit greater absorbance in the ultraviolet region. This behavior suggests that the nanocomposites have potential for utilization in optoelectronics applications. The optical properties including absorbance, absorption coefficient, extinction coefficient, refractive index, real and imaginary dielectric constant, and optical conductivity, exhibit an upward trend with increasing concentrations of SnO2/Cr2O3 nanoparticles. At a concentration of 6 wt.%, the allowed and forbidden indirect transitions exhibit a reduction in their optical energy gap from 4.38 to 2.53 eV and from 3.67 to 1.4 eV, respectively. This nanostructured composition tested the first time for the optoelectrical applications. The results showed that the PVA/SnO2/Cr2O3 nanostructures can be considered as promising nanostructures for optics, photonics and electronics nanodevices. [ABSTRACT FROM AUTHOR]

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The current study aims to process silicon dioxide (SiO2) and chromium trioxide (Cr2O3) nanostructures doped polyvinyl alcohol (PVA), and carboxymethyl cellulose (CMC) blend as promising nanostructures to apply for nanoelectronics devices and pressure sensors with low cost and excellent chemical and physical characteristics compared of other nanomaterials. Nanostructures of (PVA-CMC-SiO2–Cr2O3) were examined for their structural, morphological, and dielectric properties. Scanning electron microscope (SEM) images of (PVA-CMC-SiO2–Cr2O3) nanocomposites (NCs) reveal many aggregates or chunks that are homogenous and coherent on the top surface. When the proportion is (8 wt%), optical microscope images reveal that inside the polymers, (SiO2–Cr2O3) nanoparticles build a continuous network once compared to pure (PVA-CMC) film. Fourier transform infrared ray (FTIR) indicated a shift in peak location and a peak shape and intensity modification. The electrical properties of alternating current demonstrate that the dielectric constant (ε′) and dielectric loss (ε″) of nanocomposites drop as the frequency of the applied electrical field increases but increases when the concentration of nanoparticles (NPs) increases. The dielectric constant and AC electrical conductivity (σa.c) of (PVA-CMC) blend enhanced by about 100% and 150%, respectively, when the (SiO2–Cr2O3) content reached (8 wt%) at a frequency (f = 100 Hz). The obtained results indicated that the doping (PVA-CMC) with (SiO2–Cr2O3) NPs improved the structural and AC electrical conductivity, which made the (PVA-CMC-SiO2–Cr2O3) nanostructures promising materials for various electrical nanodevices. Compared to existing pressure sensors, the (PVA-CMC-SiO2–Cr2O3) nanostructures demonstrated superior pressure sensitivity, great flexibility, and strong environmental resilience. [ABSTRACT FROM AUTHOR]

In this article, the authors analyse the recent Parliament v Commission judgment on chromium trioxide, in light of previous case law on the authorisation procedure under the Regulation on Registration, Evaluation, Authorisation and Restriction of Chemicals ('REACH'). In the second part of the article, the authors then explore the future of the authorisation procedure, in the context of the current REACH revision, and what it could mean for the Commission's future new decision on chromium trioxide following the Parliament v Commission judgment. [ABSTRACT FROM AUTHOR]

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Introduction: The perennial grass-legume cropping system benefits soil because of its high biomass turnover, cover cropping nature, and different foraging behaviors. We investigated the response of soil organic carbon (SOC) pools and their stock to organic and inorganic nutrientmanagement in the Guinea grass and legume (cowpea-Egyptian clover) cropping system. Methods: Depth-wise soil samples were collected after harvesting the Egyptian clover. Based on the ease of oxidation with chromic acid, different pools of SOC oxidizable using the Walkley-Black C method, very labile, labile, less labile, non-labile; and dissolved organic C (DOC), microbial biomass C (MBC), and total organic C (TOC) in soils were analyzed for computing several indices of SOC. Result and discussion: After 10 years of crop cycles, FYM and NPKF nutrient management recorded greater DOC, MBC, SOC stocks, and C sequestration than the NPK. Stocks of all SOC pools and carbon management index (CMI) decreased with soil depth. A significant improvement in CMI, stratification ratio, sensitivity indices, and sustainable yield index was observed under FYM and NPKF. This grass-legume intercropping system maintained a positive carbon balance sequestered at about 0.8Mg C ha-1 after 10 years without any external input. Approximately 44-51% of the applied carbon through manure was stabilized with SOC under this cropping system. The DOC, MBC, and SOC in passive pools were identified for predicting dry fodder yield. This study concludes that the application of organics in the perennial grass-legume inter cropping system can maintain long-term sustainability, enhance the C sequestration, and offset the carbon footprint of the farm enterprises. [ABSTRACT FROM AUTHOR]

The production of crops in saline and alkali-degraded areas is difficult due to the heterogeneous and spatial variation of soil fertility. First, their spatial variability was analyzed and maps of the spatial distribution were created using Geostatistical techniques. The fuzzy k-mean clustering analysis was then used to define Management zones in the coastal saline soils of Ramanathapuram district in Tamil Nadu. One hundred and fifty geo-referenced soil samples (30 cm depth) were taken and analyzed for pH, electrical conductivity (ECe) in the saturated paste extract (USSL method), organic carbon (OC) (Walkley-Black chromic acid wet oxidation method), calcium carbonate (CaCO3) (Rapid titration method) and available phosphorus and extractable micronutrients (Multinutrients extraction method), revealing significant variation in soil characteristics throughout the coastal saline soils of Ramanathapuram district. The most significant factors, which together accounted for four principal components and 69% of the overall variability, were pH, electrical conductivity (ECe), calcium Carbonate and available zinc. According to Geostatistical analysis, the Exponential (pH, OC (organic carbon), P, Fe, Mn and Zn) and Stable (ECe) was the best fit semivariogram ordinary kriging model with weak to moderate spatial dependence. Fuzzy k-mean clustering was also used to identify zone 1, zone 2 and zone 3. For every soil property, there was a significant difference between MZ1(zone 1), MZ2(zone 2) and MZ3(zone 3). These results also showed that cluster analysis gave farmers a chance to use location-specific nutrient management strategies by minimizing variability within the zone. The management zones can decrease agricultural inputs and environmental pollutants while increasing crop productivity. [ABSTRACT FROM AUTHOR]

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In this study, simultaneous removal of an organic matter (diazinon, DIZ) and an inorganic substance (chromium, Cr) was used. Breaking down of organic matter by UV irradiation produces various radicals, including sulfides, carboxyl, hydroxyl, hydrated electrons, and various organic radicals that are highly reactive and help us to precipitation inorganic substance (Cr). The optimal condition was 30:1 DIZ:Cr molar ratio, pH 9, and about 100% and 82.3% of DIZ and Cr were obtained in 30 min. Cr deposition was very slow at first. After the destruction of the DIZ structure, Cr deposition began, and various types of sludge with disturbed properties were formed. These sledges were analyzed by FTIR analysis and showed that green sludge could be chromium (III) hydroxide; brown sludge due to chromium (III) hydroxide, tiny green crystals from chromium (III) oxide, red brick from chromium (II) acetate chromium trioxide, as well as black sludge caused by chromium oxide were identified. In UV/DIZ/Cr process, kobs and robs range obtained 0.33–0.15 and 16.8–23.4 $ with both Cr and DIZ concentration increased from 50 to 150 mg L−1. Also, EEO for Cr precipitation was 24.65 to 5.74 and for DIZ 12.54 to 4.73 (kwh m−3). Depending on the amount of energy consumption, TCS was 37.19 to 10.47 for Cr precipitation and 4.46 to 1.25 $. It is important to note that when both pollutants are exposed to ultraviolet light, more energy and cost are generally required from UV/DIZ process and less than of UV/Cr process. But it should be noted that in fact 50 mg L−1 of chromium and 50 mg L−1 of DIZ are being removed at the same time. In UV/DIZ and UV/Cr processes that are exposed to ultraviolet radiation alone, only one of them is removed. Also, when these two pollutants are being removed at the same time, the total amount of energy is much less than the total energy consumption of the pollutants one by one. [ABSTRACT FROM AUTHOR]

A chromium trioxide coating was prepared on the surface of electronic ceramics by screen printing, and solid-phase sintering was carried out at 1350 °C. The surface roughness and surface resistance characteristics of composite coatings with different chromium trioxide contents were studied. The analysis results indicate that the average thickness of Cr 2 O 3 coating is about 19.89 μm. The main crystal phase is (Al 0.9 Cr 0.1) 2 O 3. SEM shows that the surface "pores" and surface roughness of the coating change with the content of Cr 2 O 3. AFM shows that when the Cr 2 O 3 content in the coating is 0.0921 mol, the surface roughness changes the most, and the corresponding surface resistivity of Al 2 O 3 insulating ceramics decreases to the lowest, from 1016 Ω to 1012 Ω. An increase in surface roughness can lead to changes in the incidence angle of electrons, reducing the probability of electron surface collision. The lower the surface resistivity, the better the high-voltage breakdown resistance of vacuum ceramic devices, thereby improving the surface flashover performance of ceramics. • The surface resistivity of Al 2 O 3 insulating ceramics decreases from 1016 Ω to 1012 Ω. • Chromium trioxide/ceramic composite coating was prepared with thickness about 19.89 μm. • An increase in surface roughness can lead to improve the surface flashover performance of ceramics. • The "pores" on the coating surface inhibit the movement of charge. [ABSTRACT FROM AUTHOR]

Hard chromium coatings have demonstrated their performance for several decades, particularly for their wear and corrosion resistance properties. However, the traditional process using chromium trioxide (CrO3) is very toxic and is intended to disappear in the European Union by 2024, thanks to the REACH regulation. This study aimed to determine the residual stress of amorphous chromium deposits elaborated from baths containing trivalent chromium ions. However, the amorphous structure of these deposits does not allow the determination of residual stresses by conventional means. In this study, we propose adapting a recent method called "FIB-DIC", which is not limited by the material's crystalline structure compared to the classical X-ray diffraction (XRD) analysis. The method is based on the measurement of relaxation-induced displacement fields following the ablation of material on a very local scale. The results obtained by the classical (XRD) and the FIB-DIC method on crystallized heat-treated Cr(III) deposits are 296 ± 45 and 377 ± 275 MPa. Then, the FIB-DIC technique allowed us to evaluate a residual stress level of 479 ± 359 MPa for amorphous trivalent chromium coating, which has never been performed before. [ABSTRACT FROM AUTHOR]

Copyright of Electroplating & Finishing is the property of Electroplating & Finishing Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Ethanol was used as the solvent in the process of producing chromium benzoic acid complexes by combining CrO3 (chromium trioxide) and benzoic acid. Its spectrum characteristics were evaluated by the use of elemental analysis, FAB-Mass Spectroscopy,¹ HNMR spectroscopy, FTIR Spectroscopy, UV-Vis Spectroscopy, and ICP-OES, and its thermal decomposition has been studied through DSC. The Objective was to get inside of thermal stability, the heat of energy, and the rate of decomposition of the complexes. The kinetic parameter, low amount of activation energy, and enthalpy of reaction, all pointed to the complexes having a high degree of liability. [ABSTRACT FROM AUTHOR]

Described is our effort toward establishing a practical and sustainable synthesis of bis(2‐hydroxy‐3,5‐di‐t‐butylphenyl)methanone. In it, we found the phenol‐aldehyde condensation could be efficiently catalyzed by sulfonic acid‐functionalized microporous carbon spheres (MCS‐SO3H). Additionally, we developed practical and sustainable procedures for the synthesis of the title ligand by applying readily available reagents in lieu of toxic chromium trioxide and fuming boron tribromide. [ABSTRACT FROM AUTHOR]

Methods of synthesis of phosphonmethylated acetoxymethyl derivatives of acetylfurans and alkyl furoates have been developed and their methanolysis was studied. It has been found that due to the high acidity of hydroxymethylfuran derivatives, the reaction proceeds to completion only with an equivalent amount of methylate. If the acetoxymethyl and diethoxyphosphoryl groups occupy adjacent positions in the furan ring, transesterification of the phosphonate group occurs, accompanied by the destruction of P–C bond. The ester group is transesterified in any case. The resulting alcohols are oxidized by the dimethyl sulfoxide–acetic anhydride system or by the complex of chromium trioxide with pyridine to the corresponding aldehydes. The P–C bond is not affected in this case. The resulting aldoketones react with hydrazine hydrate to form furo[2,3-d]- or furo[3,4-d]pyridazines, depending on the location of substituents in the furan ring. In the case of aldoesters having similar structure, the reaction stops at the stage of formation of hydrazones. [ABSTRACT FROM AUTHOR]

The paper presents the issues of metal surface treatment in fibre metal laminates (FML) to obtain high adhesion at the metal–composite interface. Aluminium 2024-T3 and titanium Grade 2 were analysed. The metal surface modifications were carried out by mechanical (sandblasting, Scotch-Brite abrasion), chemical (P2 etching, phosphate-fluoride process), electrochemical (chromic and sulphuric acid anodizing), and plasma treatment, as well as the application of sol-gel coatings. In terms of surface geometry, the analysis included roughness and 3D surface topography examination. The morphology was examined using scanning electron and atomic force microscopy. The surface free energy and its components (polar and dispersive) were determined using the Owens–Wendt method. The novelty of this study is the determination of the effect of different surface treatments on the surface free energy, topography, and morphology in terms of the possible appropriate adhesion in fibre metal laminates. Chromic acid anodizing is still the most effective in enhancing the expected adhesion. A suitable technique may be the use of P2 etching of aluminium. It results in low roughness, numerous micro-irregularities, and the presence of porosity. The obtained test results show that the application of sol-gel coating increases the surface free energy and may increase the adhesion. [ABSTRACT FROM AUTHOR]

The adhesion strength between electroless copper and acrylonitrile-butadiene-styrene (ABS) resin could be improved significantly by MnO2-H3PO4-H2SO4 colloid system. In this paper, when the concentrations of H3PO4 and H2SO4 in the colloid were 4.2 and 10.4 M, respectively, the effect of the ultrasound-assisted etching (UAE) time on the etching performance of ABS resin were investigated. With the UAE for 10 min, much more uniform cavities formed on the ABS surface, the average surface roughness (Ra) decreased from 143 to 107 nm, which was much lower than etched by CrO3-H2SO4 colloid (420 nm). Though the average surface roughness (Ra) was decreased, the average adhesion strength between the electroless copper film and ABS substrate increased from 1.39 to 1.60 kN m−1, which was also higher than chromic acid etching treatment (1.42 kN m−1). The density of the hydrophilic groups and the uniformity of cavities on the ABS surface were increased with the UAE, which resulted in high adhesion strength and low average surface roughness. [ABSTRACT FROM AUTHOR]

This article is devoted to the investigation of the sensing behavior of chemically treated multi-walled carbon nanotubes (MWNTs) at room temperature. Chemical treatment of MWNTs was carried out with a solution of either sulfuric or chromic acids. The materials obtained were investigated by transmission electron microscopy, scanning electron microscopy, Raman-spectroscopy, X-ray diffraction, and Fourier transform infrared spectroscopy. The active layer of chemiresistive gas sensors was obtained by cold pressing (compaction) at 11 MPa of powders of bare and treated multi-walled carbon nanotubes. The sensing properties of pellets were investigated using a custom dynamic type of station at room temperature (25 ± 2 °C). Detection of NO2 was performed in synthetic air (79 vol% N2, 21 vol% O2). It was found that the chemical treatment significantly affects the sensing properties of multi-walled carbon nanotubes, which is indicated by increasing the response of the sensors toward 100–500 ppm NO2 and lower concentrations. [ABSTRACT FROM AUTHOR]

[Display omitted] • Design and fabrication of Cr 2 O 3 doped PVP nanofibers through electrospun deposition. • Crystallinity and diameter of the nanofibers depends on Cr 2 O 3 concentration. • Sensitivity of the PVP/Cr 2 O 3 detector to UV-light emission strongly depends on Cr 2 O 3 concentration. • Optimum responsivity and specific detectives were achieved at a Cr 2 O 3 concentration of 2%. Herein, chromium trioxide (Cr 2 O 3) doped Polyvinylpyrrolidone (PVP) nanofibers with high crystallinity and UV light sensitivity are successfully grown onto the glass substrates by electrospun deposition at room temperature. The effect of Cr 2 O 3 concentration on the morphology, structure, and photoluminescence properties of the as-fabricated PVP nanofibers is examined. With the increase in doping concentration of Cr 2 O 3 (i.e., 1, 2 and 3 %), the direct band gap of PVP nanofibers is reduced to 4.05, 4.01, and 3.85 eV, respectively. XRD and FE-SEM results manifest that the crystallinity and diameter of the nanofibers are dependent upon Cr 2 O 3 concentration, i.e., the mean diameter decreases from 600 to 200 nm. Photoluminescence spectra indicate higher UV emission upon the addition of Cr 2 O 3 , with greater emission near the band edge for thinner nanofibers. A possible mechanism for the formation of PVP/Cr 2 O 3 nanofibers is addressed in detail. Furthermore, it is found that the sensitivity of the as-fabricated PVP/Cr 2 O 3 detector to UV-light emission strongly depends on Cr 2 O 3 concentration, i.e., good responsivity (2.257 A/W) and specific detectives (9.8 × 1012 cm Hz1/2/W) at a Cr 2 O 3 concentration of 2 % are achieved at a wavelength of 454.1 nm, besides recording the lowest rise and fall times. [ABSTRACT FROM AUTHOR]

Pomelo peel extract passivated copper foil (PP-Cu foil) has good anti-corrosion properties in air, chlorine-containing solution, and organic electrolyte. [Display omitted] • An environmentally friendly passivator for Cu foil is prepared from pomelo peel (PP) by a simple and economical solution extraction method. • PP-Cu foil has good anti-corrosion properties in air, chlorine-containing solution, and organic electrolyte. • The copper foil treated by PP still has excellent conductivity and electrochemical performance as lithium-ion battery current collector. Passivation treatment is the last key process to ensure the service life of copper foil for lithium-ion batteries. Although chromic anhydride commonly used in industry has an efficient passivation effect, it can threat human health and the environment. Herein, an environmentally friendly passivator is prepared from pomelo peel by a simple and economical solution extraction method, which makes copper foil have good anti-corrosion properties in air, chlorine-containing solution, and organic electrolyte. Electrochemical methods and X-ray photoelectron spectroscopy (XPS) confirm the potential of pomelo peel extractant (PP) to replace chromic anhydride as a passivating agent for copper foil. The interaction mechanism between PP and copper foil is analyzed by adsorption models, and the efficient passivation behavior of PP for copper foil is consistent with the Langmuir model. Density Functional Theory (DFT) calculations of the naringin (main component of PP) is performed to further reveal the protection mechanism of PP on copper foil. In addition, the copper foil treated by PP still has excellent electrochemical performance as lithium-ion battery current collector, indicating that the presence of PP not only protects the copper foil from corrosion, but also does not affect the conductivity of the copper foil. This research provides a new insight into the chrome-free passivation of copper foils, which is in line with the development concept of green production. [ABSTRACT FROM AUTHOR]

Measurement of nutrient digestibility is a key pillar in estimating the value of feeds for livestock. Conditions are not always amendable to estimating feed digestibility through total collection methods, and as a result digestibility markers are frequently employed. The first “Digestibility markers” were reported in the early 1900s where colored glass beads were used to estimate the flow of digesta through the digestive tract. Subsequently, a myriad of digestibility markers has been assessed with the internal markers; acid insoluble ash, acid detergent lignin, indigestible neutral detergent fiber and n-alkanes and the external markers titanium dioxide and chromic oxide being the most common. Chromic oxide (Cr2 O3) was first proposed as a digestibility maker in 1918 and continues to be widely used in modern day metabolism, confined performance and grazing livestock experiments. It was the demand to use chromic acid as a digestibility marker that led Terry and Mira Fenton to publish the article “An improved procedure for the determination of chromic oxide in feed and feces” in the Canadian Journal of Animal Science in 1979. This became the most cited article in the history of the journal with over 800 citations. The procedure eliminated the use of nitric acid in a pre-digestion step and ashing reduced the organic matter content, making it less likely that perchloric acid would be converted to anhydrous perchloric acid which poses an explosive hazard. The procedure continues to be widely used to measure Cr2 O3 as a digestibility marker and has made a significant contribution to our assessment of the value of a wide range of feeds for Canadian livestock. [ABSTRACT FROM AUTHOR]

Copyright of Electroplating & Finishing is the property of Electroplating & Finishing Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

If fixation is not adequate, the other processes that follow such as dehydration, clearing, infiltration, embedding, microtomy and staining, will also be inadequate. A poorly processed tissue will make it difficult for the Pathologist/Histoscientist to render a proper diagnosis. This article is aimed at elucidating more on fixatives and fixation process in histopathology. The information presented in this review was gathered primarily from an extensive literature search on PubMed, Scopus and Textbooks. Fixatives in histopathology can be grouped into simple and compound fixatives. Simple fixative is a solution or gas which contains only one active ingredient or that has a singlechemical solution. Examples include; Formaldehyde, Glutaraldehyde, Mercuric Chloride, Potassium Dichromate, Picric Acid, Osmium Tetroxide, Acetic Acid, Ethanol, Acetone and Chromic Acid. When two or more simple fixatives are combined in a solution, the resulting solution is called a compound fixative. This can be further divided into Microanatomical and cytological fixatives. Examples of a micro-anatomical fixatives include; 10% formal-saline, Heidenhain's Susa, Boiun's fluid, Formol Sublimate. Cytological fixatives are grouped into cytoplasmic and nuclear fixatives. Fixation terminates any ongoing biochemical reactions, and also increases the mechanical strength or stability of the treated tissues. To accomplish this, tissue samples are usually immersed immediately in a fixative fluid. The fixatives employed prevent autolysis and putrefaction from taking place. Fixatives are integral substances used in histopathology to forestall the actions of autolysis and putrefaction in tissue samples. [ABSTRACT FROM AUTHOR]

Aluminum alloys are known to have many advantages (e.g., light weight and low cost) but they are not immune to corrosion. So, it is important to assess their corrosion behavior, in particular under atmospheric conditions. To protect aluminum alloys against corrosion, paints are generally applied onto the materials. Corrosion protection in the aerospace industry consists of a conversion or anodized coating, an inhibited primer, and a top-coat. Chromate conversion coating (CCC) and primers containing chromate pigments have been widely used in the aerospace industry over the last decades. However, new environmental regulations have led to major changes for aluminum corrosion protection. By limiting or prohibiting some chemicals, for instance Cr(VI), the European regulation REACH (Regulation on Registration Evaluation, Authorization and Restriction of Chemicals) has induced major changes to some of the finishing processes of aluminum alloys (e.g., chromate conversion, chromic acid anodizing, and chromate sealing). Interesting results have been obtained while seeking replacements for Cr(VI), for example, with the incorporation of cerium, lithium salt, or nanocontainers loaded with corrosion inhibitors in organic coatings. For several years, hybrid sol–gel coatings able to replace the pre-treatment and primer steps have been under development, showing interesting results. New prospects for the future involve the use of photopolymerization to reduce the energy-intensive heat treatment needed in sol–gel technology. It will also be necessary to test these new technologies in service conditions or in accelerated corrosion tests before being able to conclude on the real effectiveness of these coatings. This review summarizes the recent developments in Cr-free coatings for aluminum alloys. Their advantages and drawbacks are also discussed. [ABSTRACT FROM AUTHOR]

Pirenoxine (Scheme 1, ( B 1 b )) is a medication used in the treatment and prevention of cataracts.[1] Pirenoxine is sold under the trade name Catalin. Summing up, this new procedure replaces inherently hazardous and expensive potassium ferricyanide with inexpensive and eco-friendly ferric chloride for the preparation on decagram scale in very good yield of a key intermediate in the synthesis of Pirenoxine. According to the literature,[[2], [4]] 5,8-dihydro-4,6-dihydroxy-5,8-dioxoquinoline-2-carboxylic acid ( B 2 b ) is in turn prepared by the oxidation of 4,5,6,8-tetrahydroxyquinoline-2-carboxylic acid ( B 4 b ) in the presence of potassium ferricyanide and sulfuric acid in water as shown in Scheme 2 (a).[2] However, the major disadvantage of this synthesis is the use of potassium ferricyanide. [Extracted from the article]

Chromium (III) salicylate and Chromium (III) benzoate complexes were prepared using Chromium trioxide and different molar concentrations of salicylic and benzoic acid. Tertiary amyl alcohol and ethanol are used as a solvent. 1HNMR spectra of solid samples were recorded. 1HNMR spectra of metal complexes suggest that deprotonation of - COOH group took place, and the complex formed was not through the -OH of the acid. It confirms the coordination of the ligand to the metal ion through the carboxylic oxygen atom. [ABSTRACT FROM AUTHOR]

The microstructure, corrosion behavior, and electrochemical behavior of as-cast Mg-4Y-xZn (x=1,2,3,4 wt.%) are studied by SEM, weight loss and electrochemical tests. Mg12YZn (X), Mg3Y2Zn3 (W) and Mg24Y5 constitute the phase composition system of the alloy. When Zn content is 1 wt.%, all tests reveal that alloy has the optimal corrosion performance. The second phase in these alloys, due to their nobler nature than α-Mg, exists as a cathode during the corrosion process, so that α-Mg preferentially occurs corrosion to accelerate the formation of corrosion pits. After soaking in 3.5 wt.% NaCl solution for some time, the stability of the W phase changed, and gradually dissolved, which was finally removed by chromic acid used for removal of corrosion products. In addition, X phase can be used as an anode in the micro-galvanic cells formed with W phase to reduce the corrosion rate of α-Mg and thus improve the corrosion performance of the alloy. [ABSTRACT FROM AUTHOR]

Chromic acid oxidation of d,l -mandelic acid in the presence and absence of 1,10-phenanthroline (Phen) is studied in an aqueous micellar medium under kinetic conditions, [ d,l -mandelic acid] >> [Phen]T >> [Cr(VI)]T at different temperatures. From studies on the effect of temperature on the rate constant (k), the activation parameters ∆H≠ (enthalpy of activation) and ∆S≠ (entropy of activation) are evaluated by using the Eyring equation [−ln (kh/kBT) = ∆H≠/RT − ∆S≠/R]. The high value of ∆H≠ indicates that the phen-catalysed path is favoured mainly due to very high negative value of ∆S≠. The negative value of ∆S≠ and the composite rate constant k cat support the suggested cyclic transition state. Both the catalysed and uncatalysed paths show a first-order dependence on [H+], and both also show a first-order dependence on [ d,l -mandelic acid]T and [Cr(VI)]T. The Phen-catalysed path is first order in [Phen]T. These observations remain unaltered in the presence of externally added surfactants. The cationic surfactant N -cetylpyridinium chloride is found to retard the rate of the reaction. [ABSTRACT FROM AUTHOR]

The application of polyolefins has increased significantly over the past few decades. However, their chemical inertness and low surface energy limits their application in many industries where high adhesion to polar materials is required, such as for composites and protective coatings. Herein, six different acids are used to create polar functional groups on High‐Density Polyethylene's (HDPE) surface and to increase its adhesion to liquid epoxy (LE). Contact angle measurements, Fourier Transform Infrared Spectroscopy (FTIR), X‐ray Photoelectron Spectroscopy (XPS), and pull‐off strength measurements are used to analyze the surface energy and functionality of HDPE and to measure its adhesion to LE. The results show that each acid increases both the polar and disperse surface energies of HDPE to a different extent, but that this is not necessarily a function of acid strength. Chlorosulfonic acid and chromic acid increase the oxygen to carbon ratio by a factor of 8 and increase HDPE's adhesion to LE by more than 400%. Furthermore, a comparison between predicted work of adhesion values from the OWRK model and experimental results shows that the latter are significantly higher than what is predicted, especially with increasing surface polarity. [ABSTRACT FROM AUTHOR]