Traditional Cr Research Articles

Preparation and anticorrosion properties of Co-Ti-Zr composite conversion coating on 6061 aluminium alloy of the scooter profile

The traditional Cr conversion process is limited in industrial application due to environmental protection issues. The relationship between the morphology, composition and corrosion resistance of the Co-Ti-Zr composite conversion coating was systematically studied by dropping test, electrochemical test, SEM, EDX and XPS. The results show that the best conversion temperature and conversion time of CoTiZrCC is 40 ℃ and 18 min, respectively. The CoTiZrCC formed under the optimal conversion parameters is continuous and compact with the main elements of Co, Ti, Zr and Al on the surface, and its main phases are TiO2, ZrO2, Al2O3 and a small amount of fluoride. Additionally, the CoTiZrCC has lower self-corrosion current and higher film resistance, thereby greatly improving the corrosion resistance of the aluminum alloy substrate.

Feasibility and effectiveness of cardiac telerehabilitation for older adults with coronary heart disease patients: a pilot randomized controlled trial

Abstract Background Cardiac rehabilitation is a standard and multidisciplinary treatment of exercise promotion, patient education, risk factor management, and psychosocial counseling for people with coronary heart disease (CHD) that is underutilized due to disparities in access, referral, and participation. Empirical studies suggest that cardiac telerehabilitation (CTR) have safety and efficacy comparable to traditional in-person CR, however, older adults are under-reported with effectiveness, feasibility, and usability of CTR for this population remains unclear . Purpose This study investigates the effects, usability, and feasibility of 12-week CTR on health outcomes of older people with CHD. Design A pilot randomized controlled trial with qualitative process evaluation. Methods The study randomized 43 older adults with CHD to the 12-week CTR intervention or usual care. Guided by Social Cognitive Theory, intervention group participants received individualized in-person assessment and orientation session, followed by CTR usage at home. Participants were encouraged to visit the CR website for self-learning and data uploading, use the pedometer for daily step tracking, and chat with peers and CR nurse via social media for problem-solving and mutual support. Data were collected at baseline (T0), six-week (T1), and 12-week (T2). Results Participants in the CTR intervention group showed significant improvement in daily steps (T1: β=4126.58, p=0.001; T2: β=5285, p=0.01) and health-promoting lifestyle profile (T1: β= 23.26, p<.001; T2: β=12.18, p=0.008) across study endpoints. No significant difference was observed regarding self-efficacy, quality of life, psychological symptoms, and body weight and blood pressure. Twenty participants completed the intervention, with 100% used social media for tele-consultation, 90% used the pedometer for tele-monitoring, 40% (n=8) used the website. Improving awareness on rehabilitation and a clear action focus were considered as key enablers while physical discomforts and difficulties in using the technology were described as main barriers. Conclusions The CTR is effective in improving physical activity and healthy behaviors for older adults. Considering the variation in individual cardiovascular risk factors, full-scale RCT with larger sample is needed to determine the effect of CTR on psychological symptoms, body weight and blood pressure, and quality of life. Strategies to improve user intervention usage is needed.

Evaluation of the efficacy and safety of an integrated telerehabilitation platform for home-based cardiac REHABilitation in patients with heart failure (E-REHAB): protocol for a randomised controlled trial

IntroductionCardiac rehabilitation (CR) is strongly recommended as a medical treatment to improve the prognosis and quality of life of patients with heart failure (HF); however, participation rates in CR are...

Improved thermal stability and irradiation tolerance of oxide dispersion strengthened chromium coatings

A novel Cr coating with uniformly dispersed yttrium-based nano-oxides (i.e., ODS-Cr coating) was synthesized. Structural analyses show that, after heat treatments, the grain coarsening was not detected, and mechanical properties remained almost intact in ODS-Cr coatings while the grain size increased six times and mechanical properties degraded remarkably for pure Cr coatings. Irradiation-induced cavities in ODS-Cr coatings were also greatly suppressed compared with those in pure Cr coating. These results indicate that the ODS-Cr coating has a better mechanical properties and irradiation resistance than traditional pure Cr, and highlight its potential application as protective coatings for ATF solutions.

Efficient all-in-one removal of total chromium over nonconjugated polymer-inorganic ZnIn2S4 semiconductor hybrid

Chromium (Cr)-containing wastewater has caused a serious threat to the environment due to its high toxicity and mobility. The traditional Cr removal methods are generally based on an inconvenient two-step process with the first transformation of Cr(VI) to Cr(III) and the consecutive removal of Cr(III) by precipitation. Herein, we demonstrate the efficient all-in-one removal of total Cr through the simultaneous photocatalytic reduction of Cr(VI) to Cr(III) and in-situ fixation of Cr(III) over the nonconjugated polymer engineered ZnIn2S4 (P-ZIS) photocatalyst. By in-situ polyvinylpyrrolidone (PVP) modification of ZIS during the preparation process, the resulted P-ZIS can completely reduce Cr(VI) within 60 min under visible light irradiation. The kinetics of Cr(VI) reduction over P-ZIS is 2.8 times as that of pure ZIS, which is proved to be benefited from the enhanced light absorption, uplifted conduction band for strengthening reducibility, and accelerated charge carrier transfer. Moreover, as compared to ZIS, P-ZIS also exhibits significantly improved in-situ adsorption ability for Cr(III), thus resulting in efficient all-in-one elimination of total Cr within a single system. We show that this polymer engineered strategy could be a facile and versatile protocol for modulating the electronic structure and surface chemistry of the semiconductor photocatalysts towards complete, safe, and cost-efficient removal of Cr.

An immersed [formula omitted]-[formula omitted] element for Stokes interface problems and the optimal convergence analysis

This paper presents and analyzes an immersed finite element (IFE) method for solving Stokes interface problems with a piecewise constant viscosity coefficient that has a jump across the interface. In the method, the triangulation does not need to fit the interface and the IFE spaces are constructed from the traditional CR−P0 element with modifications near the interface according to the interface jump conditions. We prove that the IFE basis functions are unisolvent on arbitrary triangles without any angle conditions and the IFE spaces have the optimal approximation capabilities, although the proof is challenging due to the coupling of the velocity and the pressure. The stability and the optimal error estimates of the proposed IFE method are also derived rigorously. The constants in the error estimates are shown to be independent of the interface location relative to the triangulation. Numerical examples are provided to verify the theoretical results.

Acorus calamus L. constructed wetland-microbial fuel cell for Cr(VI)-containing wastewater treatment and bioelectricity production

Due to chemical agents consumption and energy demand during traditional Cr(VI)-containing wastewater treatments, it is essential to explore a cost-effective and sustainable technique to remove Cr(VI) from wastewater. Combining of phytoremediation and bio-electrochemical technology, an Acorus calamus L. constructed wetland-microbial fuel cell (CW-MFC) was ingeniously designed to purify Cr(VI)-containing wastewater and harvest bioelectricity, and possible Cr(VI) removal routes were explored. Acorus calamus L. increased the CW-MFC voltage by approximately 69.75%, and maximum power density reached 36.43 mW m−2. After 9 h, the planted CW-MFC achieved Cr(VI) removal efficiency of 98.92% at an influent Cr(VI) concentration of 12.07 mg/L, while only 76.43% of the Cr(VI) was eliminated in the unplanted CW-MFC. The Cr(VI) removal was achieved mainly through bio-electrochemical reduction and plant uptake, which accounted for 53–67% and 22–33%, respectively. The addition of low concentrations of Cr(VI) improved the CW-MFC power generation, while high levels of Cr(VI) resulted in power decline. The highest maximum power density of 46.63 mW m−2 was observed when influent Cr(VI) concentration was 6.69 mg/L. The CW-MFC's Cr(VI) removal conformed to the first-order reaction kinetics, and a high rate constant of 0.2887 h−1 was achieved even at a Cr(VI) concentration of 18.21 mg/L. The main removal pathway of Cr was associated with cathodic bio-electrochemical reduction of Cr(VI) to Cr(III) and Cr(OH)3 precipitation, and the final fate of Cr was comprehensively analyzed. The obtained research results provide an important reference for the practical application of CW-MFC in Cr(VI)-containing wastewater treatment.

Preparation and rheological Evaluation of a thixotropic polymer gel for water shutoff in fractured tight reservoirs

In this study, a thixotropic and high-strength gel system (THSG) is developed, which is experimentally proven to be feasible for conformance control in fractured reservoirs. The THSG is based on in-situ polymerization of the acrylamide monomer, incorporating a weak gel system. It is found that the superior rheological properties of THSG are beneficial for injection and placement of gelant into the fractures. The viscosity of THSG at varying shear rates can be well fit by the Carreau–Yasuda model, and its shear thinning behavior contributes to low injection pressure during the gelant injection. Moreover, this THSG system exhibits much better thixotropy than the traditional Cr(Ⅲ)-acetate-HPAM gel system (HPAM/Cr(Ⅲ) gel), which would enable the THSG an easier access to the small apertures. It is also found that the injection pressure is greatly increased with decreasing of the diameter of aperture during injection of the HPAM/Cr(Ⅲ) gel, while little effect of the aperture size on injection pressure was observed during THSG injection. Additionally, the yield stress of the thixotropic gelant is noticeably high, which would greatly mitigate the adverse effect of gravity segregation in fractures during well shut-off. This would be also beneficial for plugging the whole fractures. To better understand the properties of THSG, the gelation performance, the microstructure of the gel and the blocking ability of gel in the tubes were investigated. The results show that the clay particles strengthened gel exhibits a large storage modulus and excellent thermal stability. Scanning electron microscopy (SEM) results show that the clay particles were readily distributed on the polymer chains, and the clay particles could facilitate the gel to form a firm and uniform network. Consequently, the clay particles strengthened THSG gels have relatively high rupture pressure, which would be exceedingly favorable for efficient gel treatments in fractured reservoirs. • Rheology behaviors of the THSG have been studied. • The flow curve of the THEG can be well described by the Carreau–Yasuda model. • The THSG has a typical thixotropic behavior, which can effectively plug the entire fractures. • The injection pressure of the THSG is almost irrelevant to the apertures.

The efficacy of incorporating mental imagery in cognitive restructuring techniques on reducing hostility: A randomized controlled trial

Background and objectivesCognitive restructuring (CR) is an effective intervention for hostility. However, the number of patients who fail to benefit suggest that the efficacy of CR can be further improved. The present study investigated whether enhancing CR with mental imagery techniques can increase its efficacy. MethodsA high hostility sample (28% male, and 72% female) was randomized over one session of imagery enhanced CR (I-CR) (n = 34), traditional CR (n = 32) or an active control session (AC) (n = 21). Changes in hostile beliefs, aggressive tendencies, state anger and hostility traits were assessed pre- and post-treatment, and at one-week follow-up. ResultsResults showed that both I-CR and CR efficaciously reduced hostile beliefs, aggressive tendencies and anger, to a stronger degree than AC. I-CR was more efficacious and sustainable over time than both CR and AC in reducing hostile beliefs and aggressive tendencies. LimitationsThis study was conducted using a small, non-treatment seeking sample. ConclusionsFindings suggest that implementing imagery techniques in CR for hostile beliefs enhances its’ efficacy.

A Study of the Effect of Ligand-Metal Interactions on the Electrodeposition of Chromium from Trivalent Chromium Electrolytes

With electrolytic chromium coated steel (ECCS) technology, a thin layer of chromium and an outer layer of chromium oxide are deposited on packaging steel to provide corrosion protection and a suitable layer for adhesion of subsequent polymer coatings. In an ECCS plating line, the coating is deposited via a hexavalent chromium electrolyte. Hexavalent chromium has been found to be an environmental and health hazard and is therefore subject to restrictions under REACH legislation. A new coating process based on trivalent chromium chemistry has therefore been developed (TCCT).Coatings produced via trivalent chromium electrolytes have been found to provide comparable corrosion resistance to those achieved with the traditional Cr(VI)-based process [1]–[4]. However, there is limited understanding of the mechanism and kinetics of electrodeposition from trivalent chromium based electrolytes. This knowledge is key to optimizing process design of industrial plating lines. Formate ions are incorporated in the Cr3+ electrolyte as complexing agents to make Cr0 deposition possible. It has been shown that coating composition is dependent on the relative quantity of HCOO- ions present. The present study is comprised of two main research goals - to determine the complexes that form in solution as a function of the relative complexing agent (HCOO-) concentration and to determine the effect of this complex speciation on the deposition mechanism.Results of a multitechnique approach addressing the first of our research goals - complex speciation - will be presented. Density functional calculations have been used to establish the energetic feasibility of the reaction mechanisms suggested by results from UV Vis and FTIR spectroscopy and rotating cylinder cyclic voltammetry experiments. UV Vis and FTIR results show that a clear chemical transition occurs once the formate ion is introduced in the electrolyte – starting ratio 1:6 HCOO-:Cr3+. Beyond this point, no significant change in the spectrum apart from increasing absorbance up to a ratio of 12 HCOO-:Cr3+ is observed. These results suggest the formation of a single new complex in the solution upon introduction of the formate ion in the electrolyte solution which is not modified by further increase of the formate ion concentration.[1] M. Inman et al., ‘Green Process for Fuctional Trialent Crhromium Electroplating’, in 223rd ECS Meeting, 2012.[2] J. H. O. J. Wijenberg, M. Steegh, M. P. Aarnts, K. R. Lammers, and J. M. C. Mol, ‘Electrodeposition of mixed chromium metal-carbide-oxide coatings from a trivalent chromium-formate electrolyte without a buffering agent’, Electrochimica Acta, vol. 173, pp. 819–826, Aug. 2015.[3] J. E. Edy, H. N. McMurray, K. R. Lammers, and A. C. A. deVooys, ‘Kinetics of corrosion-driven cathodic disbondment on organic coated trivalent chromium metal-oxide-carbide coatings on steel’, Corrosion Science, vol. 157, pp. 51–61, Aug. 2019.[4] S. Hesamedini and A. Bund, ‘Trivalent chromium conversion coatings’, J Coat Technol Res, vol. 16, no. 3, pp. 623–641, May 2019.

HBM4EU chromates study - Reflection and lessons learnt from designing and undertaking a collaborative European biomonitoring study on occupational exposure to hexavalent chromium.

The EU human biomonitoring initiative, HBM4EU, aims to co-ordinate and advance human biomonitoring (HBM) across Europe. As part of HBM4EU, we presented a protocol for a multicentre study to characterize occupational exposure to hexavalent chromium (Cr(VI)) in nine European countries (HBM4EU chromates study). This study intended to collect data on current occupational exposure and to test new indicators for chromium (Cr) biomonitoring (Cr(VI) in exhaled breath condensate and Cr in red blood cells), in addition to traditional urinary total Cr analyses. Also, data from occupational hygiene samples and biomarkers of early biological effects, including genetic and epigenetic effects, was obtained, complementing the biomonitoring information. Data collection and analysis was completed, with the project findings being made separately available. As HBM4EU prepares to embark on further European wide biomonitoring studies, we considered it important to reflect on the experiences gained through our harmonised approach. Several practical aspects are highlighted for improvement in future studies, e.g., more thorough/earlier training on the implementation of standard operating procedures for field researchers, training on the use of the data entry template, as well as improved company communications. The HBM4EU chromates study team considered that the study had successfully demonstrated the feasibility of conducting a harmonised multicentre investigation able to achieve the research aims and objectives. This was largely attributable to the engaged multidisciplinary network, committed to deliver clearly understood goals. Such networks take time and investment to develop, but are priceless in terms of their ability to deliver and facilitate knowledge sharing and collaboration.

The effectiveness of intensive and traditional cardiac rehabilitation programs for improving cardiometabolic outcomes in patients with cardiovascular disease

Abstract Background Cardiac rehabilitation (CR) is integral to the optimal medical management of patients with cardiovascular disease (CVD). Purpose This study aims at evaluating the effectiveness of traditional (TCR) and intensive (ICR) CR programs for improving cardiometabolic outcomes of patients with CVD. Methods The study is based on retro-prospective review of hospital medical data of patients enrolled in TCR or ICR programs. TCR involved 36 supervised exercise and educational sessions (1 hr) 3 days/week over 12 weeks. ICR included a structured class model (4 hrs) twice a week over 9 weeks (a total of 18 sessions, 72 hrs). The ICR sessions were provided by a multidisciplinary team and consisted of supervised exercise, plant-based diet, nutrition education, stress management, and social support. The comparative analyses of numerous biomarkers and hemodynamic parameters before and after CR program for both groups were performed. The occurrence of major cardiac adverse events (MACE) in the long-term follow-up was assessed. Results In total, 314 patients (213 in TCR and 101 in ICR) were enrolled. Mean treatment adherence was 78% (97% in ICR vs 68% in TCR, p=0.000). Mean follow-up for MACE was 12.6 months (13.2 in ICR vs 12 in TCR, p=0.038). No differences were observed between TCR and ICR in patient age (66 years on average) and gender (68–73% of males). Coronary heart disease, hypertension, and heart failure (HF) were the most frequent CVDs in both TCR and ICR groups (88% vs 95%, p=0.044, 75% vs 66%, p=0.104, 48% vs 25%, p=0.000, respectively). There was no significant difference in incidence of diabetes and chronic kidney disease, and pharmacotherapy between groups. TCR program resulted in significant improvements in body and visceral fat, waist circumference, and exercise capacity whereas no significant changes were observed in weight, body mass index (BMI), blood pressure (BP), heart rate (HR), and lipids levels. ICR resulted in significant improvements in most metabolic biomarkers (weight, BMI, body and visceral fat, waist circumference), hemodynamic parameters (exercise capacity, BP) and lipid biomarkers levels (total cholesterol, low-density and non-high-density-lipoprotein cholesterol). Compared with TCR, ICR resulted in more significant improvements of metabolic biomarkers such as weight (p<0.001), BMI (p<0.001), body fat (p<0.05) and waist circumference (p=0.002), and hemodynamic parameters such as diastolic BP (p<001) and HR (p=0.05). A trend towards lower incidence of MACE (all-cause death, non-fatal myocardial infarction, unstable angina, and revascularisation) with significantly lower rates of hospitalisation for HF (2 vs 24, p=0.005) in the long-term follow-up was observed in ICR compared with TCR group. Conclusion Intense and more comprehensive lifestyle modification provided by the ICR program had greater impact on improving cardiometabolic outcomes including long-term MACE compared to the TCR program. Funding Acknowledgement Type of funding source: None

Effect of a lifestyle-focused electronic patient support application on risk factor management in post-myocardial infarction patients – a randomized controlled trial

Abstract Background Cardiac rehabilitation (CR) is central in reducing morbidity and mortality after myocardial infarction (MI). However, the fulfillment of guideline recommended CR targets is unsatisfactory. eHealth offers new possibilities to improve clinical care. Purpose The aim of this study was to assess the efficacy of a mobile device application to support adherence to lifestyle advice and self-control of risk factors as a complement to traditional CR after MI. Method This unblinded multi-centre randomized controlled trial included 150 patients with MI (81% men, 60.4±8.8 years). All patients in the intervention (INT) and control (CON) groups participated in a 1-year CR program. Additionally, INT patients (n=101) received access to the mobile device application for 25 weeks post-MI where information about lifestyle (i.e., diet, physical activity, smoking), modifiable risk factors (i.e., weight, blood pressure (BP)), and symptoms could be registered. The software provided direct positive feedback and lifestyle advice. Data was reviewed twice weekly by the CR nurse. The primary outcome was change in sub-maximal exercise capacity (W) between an exercise test 2-weeks post MI and at follow-up 4 month later. Secondary outcomes included changes in lifestyle and modifiable risk factors including body mass index, waist circumference, blood-lipids, fasting glucose and HbA1c, between baseline and 2-week, 2-month and 1-year follow-up visits. Regression analysis was used, adjusting for relevant baseline variables. Results Participation in CR was high, with 96% of INT patients and 98% of the CON patients attending the 1-year follow-up visit. Forty-six percent of the INT patients and 57% of the CON patients attended centre-based exercise training (p=0.1). In the INT group 86% logged data in the application at least once. Adherence, defined as logging data at least twice per week, was 92% in week 1 and 57% in week 25. There was a numerical trend toward better exercise capacity improvement in the INT group (INT +14.4±19.0 vs. CON +10.3±16.1 W, p=0.2) although differences were non-significant. INT patients achieved larger BP reduction at 2-weeks (systolic) and 2-months (systolic and diastolic) (Figure). At 2-months 70% vs. 46% of smokers in the INT vs CON groups had quit smoking, and at 1-year the respective percentages were 57% vs. 36%. The number of smokers in the study was however low (n=33) and the differences non-significant. For other secondary endpoints no differences were observed. Conclusion Complementing CR with a mobile device application improved BP during the first months after MI, and non-significant trends towards better exercise capacity and higher smoking cessation rates were observed. Even though the differences were non-significant in our small study sample, they indicate that using eHealth in the form of a mobile device application could clinically benefit post-MI patients participating in CR. Funding Acknowledgement Type of funding source: Public grant(s) – National budget only. Main funding source(s): Governmental funding of clinical research within the National Health Services in Sweden.

Hexavalent chromium in drinking water: Chemistry, challenges and future outlook on Sn(II)- and photocatalyst-based treatment.

Chromium (Cr) typically exists in either trivalent and hexavalent oxidation states in drinking water, i.e., Cr(III) and Cr(VI), with Cr(VI) of particular concern in recent years due to its high toxicity and new regulatory standards. This Account presented a critical analysis of the sources and occurrence of Cr(VI) in drinking water in the United States, analyzed the equilibrium chemistry of Cr(VI) species, summarized important redox reaction relevant to the fate of Cr(VI) in drinking water, and critically reviewed emerging Cr(VI) treatment technologies. There is a wide occurrence of Cr(VI) in US source drinking water, with a strong dependence on groundwater sources, mainly due to naturally weathering of chromium-containing aquifers. Challenges regarding traditional Cr(VI) treatment include chemical cost, generation of secondary waste and inadvertent re-generation of Cr(VI) after treatment. To overcome these challenges, reductive Cr(VI) treatment technologies based on the application of stannous tin or electron-releasing titanium dioxide photocatalyst hold extreme promise in the future. To moving forward in the right direction, three key questions need further exploration for the technology implementation, including effective management of residual waste, minimizing the risks of Cr(VI) re-occurrence downstream of drinking water treatment plant, and promote the socioeconomic drivers for Cr(VI) control in the future.

Surface Treatments Solutions to Green Tribology

The objective of this paper is to highlight the need to combine lifecycle environmental assessment with durability evaluation (tribology and engine tests) to evaluate the potential of surface technologies to contribute to the green deal, in order to make Europe the first climate-neutral continent. Tribology is a scientific discipline that allows one to understand the system reaction to friction and wear. Tribological testing machines are prepared to measure friction at the laboratory level to minimize the wear and heat dissipation of two bodies in relative movement, thus improving the energy efficiency and minimizing CO2 emissions. In this paper, different surface technologies, such as high-velocity oxyfuel (HVOF), physical vapor deposition (PVD), and clean Cr electrolytic processes, are analyzed as promising surface technology solutions from both performance and environmental impact perspectives to replace harmful Cr(VI) coatings. The tribology simulates the working conditions of the real system at the laboratory level, reproducing the failure mechanism and facilitating the laboratory screening of the energy efficiency and durability of materials solutions for certain tribological systems—in this case, engine components. The tribological test results give information about the behavior of materials, while the engine tests gives information about the behavior of components. In this paper, the environmental impact of the production process of the coatings is also analyzed. Two hard chrome processes are compared, demonstrating that by controlling the production process it is possible to significantly reduce the environmental impact of the chrome-plated process, minimizing the environmental impact to that of PVD coatings. The environmental impact of the tested HVOF process is lower than traditional Cr(VI)-plated coatings but higher than PVD coatings. Combining the information from the lifecycle assessment (LCA) and tribological studies, it is possible to assess both the performance and the environmental impact of the surface treatments. This methodology is a tool to that can be used minimize CO2 emissions at the design phase to improve the energy efficiency of products and processes.

Surface Modulation and Chromium Complexation: All-in-One Solution for the Cr(VI) Sequestration with Bifunctional Molecules

The sulfidation of zero valent iron (ZVI) to an Fe@FeSx (S-ZVI) composite has been intensively explored in the ZVI field. Yet, further benefits from the FeSx coating layer are seldom realized, especially those effectively using its intrinsic physical and chemical properties for elaborate design. Here, we demonstrate that in a traditional Cr(VI) sequestration reaction, the FeSx layer displays a great utility in immobilizing molecules containing hydroxyl groups (-OH) and hence, attracting Cr(VI) complexes chelated with carboxyl organics (RCOOH). Such intermolecular attraction readily promotes the diffusion of the Cr(VI) complexes to the S-ZVI surface, affording a higher reaction rate for the Cr(VI) sequestration process. In addition, the above mechanism was used to guide a rational selection of molecules incorporating both hydroxyl and carboxyl functional groups with a proper ratio and thereby, a significantly improved reaction efficiency was achieved. Furthermore, the FeSx phase was revealed to be consumed in the reaction, acting as a supplementary reductant. This work is the first to unveil the relationship between molecules with specific functionalization and the FeSx phase, providing a general rule in choosing appropriate reaction media for Cr(VI) sequestration and related reactions.

Effect of Ligand-Complex Interactions on the Electrodeposition of Mixed Chromium Metal-Carbide-Oxides from Trivalent Chromium Electrolytes

Electrolytic chromium coated steel (ECCS) is packaging steel coated with a thin layer of chromium with an outer layer of chromium oxide. This coating system provides corrosion protection in addition to good adhesion properties due the outer oxide layer. The coating for ECCS is deposited via a hexavalent chromium electrolyte which has been found to be an environmental and health hazard and is therefore subject to restrictions under REACH legislation. A new coating process based on trivalent chromium chemistry has therefore been developed.According to prior studies, coatings comparable in terms of corrosion resistance to those achieved with the traditional Cr(VI)-based process have been produced with this process [1]–[4]. However, at present there is limited understanding of the mechanism and kinetics of electrodeposition from trivalent chromium based electrolytes. This knowledge is key to optimize the process design for industrial plating lines. In the present study, we investigate the effect of the chemistry of the Cr(III) complex – as determined by the relative concentration of the formate complexing agent and temperature – on the electrodeposition of mixed chromium metal-carbide-oxide coatings on low carbon steel in a rotating cylinder electrode (RCE) setup.In this study, low carbon steel samples are electroplated in an aqueous Cr(III) based electrolyte bath with a deposition time of 0.8 s with applied current densities ranging from 20 to 90 A dm-2. The pH of the electrolyte is maintained at 2.6. A rotation speed of 776 RPM is used. SEM and XPS analysis is also performed to determine the effect of the above parameters on the microstructure and composition of the deposits. The amount of Cr deposited is determined using XRF measurements. Relative chromium metal, oxide and carbide contents are determined via XPS analysis. UV-Vis spectra of each of the electrolytes are also measured.Optical surface analysis shows that of the three regimes distinguishable as a function of current density [2], homogeneous, bright coatings are deposited in regime II (Figure 1). The current range over which acceptable coatings are deposited is significantly wider with higher relative ligand concentrations. Lower applied currents are required with lower bath temperatures. Increasing the chromium ion concentration (at a fixed relative ligand concentration) results in increased Cr metal deposition and an associated decrease in the carbide content of the coating. At higher bath temperatures, carbide formation is favoured. Results also indicate a threshold ligand-to-complex ratio at ~2.0 [HCOO-]/[Cr3+] above which a bright, homogeneous coating is deposited. This threshold corresponds with UV/Vis results which indicate the formation of a new complex species in the electrolyte at that ratio (Figure 2). Figure 1

Comparison of Metal Adhesion Layers for Au Films in Thermoplasmonic Applications.

If thermoplasmonic applications such as heat-assisted magnetic recording are to be commercially viable, it is necessary to optimize both thermal stability and plasmonic performance of the devices involved. In this work, a variety of different adhesion layers were investigated for their ability to reduce dewetting of sputtered 50 nm Au films on SiO2 substrates. Traditional adhesion layer metals Ti and Cr were compared with alternative materials of Al, Ta, and W. Film dewetting was shown to increase when the adhesion material diffuses through the Au layer. An adhesion layer thickness of 0.5 nm resulted in superior thermomechanical stability for all adhesion metals, with an enhancement factor of up to 200× over 5 nm thick analogues. The metals were ranked by their effectiveness in inhibiting dewetting, starting with the most effective, in the order Ta > Ti > W > Cr > Al. Finally, the Au surface-plasmon polariton response was compared for each adhesion layer, and it was found that 0.5 nm adhesion layers produced the best response, with W being the optimal adhesion layer material for plasmonic performance.

Formulation of EPDM heat-resistant V-ribbed belt

As a major pillar industry of the national industrial economy, the automobile industry has been greatly affected by the increasingly strict requirements of environmental protection in recent years. With the constant promotion of new energy vehicles, further compression of costs and improved performance will enable enterprises to occupy a place in international competition. In terms of the belt material of automobile engines, HNBR and EPDM, which are better in performance, are gradually replacing the traditional CR to adapt to the more demanding working environment. Compared with HNBR, EPDM is cheaper. In this paper, the effects of carbon black N330 and nylon staple fiber and their dosage on the properties of EPDM wedge rubber were studied by orthogonal test method to find the best formula. Studies have shown that the nylon fiber content has a great influence on the physical properties of EPDM wedge rubber, and comes to the influence of carbon black N330 content. The interaction between them is not obvious. When the content of the nylon fiber is 5phr and the content of the carbon black is 65 phr, the rubber wear rate after vulcanization is 15.5%, and the storage modulus at 120°C is about 60% at room temperature, its strength, heat resistance and aging resistance are excellent.

Setting up a collaborative European human biological monitoring study on occupational exposure to hexavalent chromium

The EU human biomonitoring initiative, HBM4EU, aims to co-ordinate and advance human biomonitoring (HBM) across Europe. Within its remit, the project is gathering new, policy relevant, EU-wide data on occupational exposure to relevant priority chemicals and developing new approaches for occupational biomonitoring. In this manuscript, the hexavalent chromium [Cr(VI)] study design is presented as the first example of this HBM4EU approach. This study involves eight European countries and plans to recruit 400 workers performing Cr(VI) surface treatment e.g. electroplating or stainless steel welding activities. The aim is to collect new data on current occupational exposure to Cr(VI) in Europe and to test new methods for Cr biomonitoring, specifically the analysis of Cr(VI) in exhaled breath condensate (EBC) and Cr in red blood cells (RBC) in addition to traditional urinary total Cr analyses. Furthermore, exposure data will be complemented with early biological effects data, including genetic and epigenetic effects. Personal air samples and wipe samples are collected in parallel to help informing the biomonitoring results. We present standard operational procedures (SOPs) to support the harmonized methodologies for the collection of occupational hygiene and HBM samples in different countries.