Association of low-level inorganic arsenic exposure from rice with age-standardized mortality risk of cardiovascular disease (CVD) in England and Wales

Adverse health outcomes, including death from cardiovascular disease (CVD), arising from chronic exposure to inorganic arsenic (iAs) are well documented. Consumption of rice is a major iAs exposure route for over 3 billion people, however, there is still a lack of epidemiological evidence demonstrating the association between iAs exposure from rice intake and CVD risks. We explored this potential association through an ecological study using data at local authority level across England and Wales. Local authority level daily per capita iAs exposure from rice (E-iAsing,rice) was estimated using ethnicity as a proxy for class of rice consumption. A series of linear and non-linear models were applied to estimate the association between E-iAsing,rice and CVD age-standardized mortality rate (ASMR), using Akaike's Information Criterion as the principle model selection criterion. When adjusted for significant confounders, notably smoking prevalence, education level, employment rate, overweight percentage, PM2.5, female percentage and medical and care establishments, the preferred non-linear model indicated that CVD risks increased with iAs exposure from rice at exposures above 0.3 μg/person/day. Also, the best-fitted linear model indicated that CVD ASMR in the highest quartile of iAs exposure (0.375–2.71 μg/person/day) was 1.06 (1.02, 1.11; p-trend <0.001) times higher than that in the lowest quartile (<0.265 μg/person/day). Notwithstanding the well-known limitations of ecological studies, this study further suggests exposure to iAs, including from rice intake, as a potentially important confounder for studies of the factors controlling CVD risks

Experimental Study on the Contact Force between the Vessel and CBF in the Integrated Floating Transportation Process of Offshore Wind Power

More and more clean energy is used worldwide and offshore wind power is an important part of clean energy. The difficulty of offshore construction is an important problem. The integrated floating transport technique of composite bucket foundation (CBF) provides an important method to solve this problem. The main purpose of this paper is to study and verify the safety of the integrated floating transport technique of the composite bucket foundation. Through the test method, we determine the location distribution where the contact force changes greatly and identify the factors that have a great impact on the contact force. We study the influencing factors of the contact force between the composite bucket foundation and the installation vessel during the towing process and verify the experimental results through project data monitoring. We conclude by proposing feasible suggestions for the safety assurance of the project based on the contact force problem

Shape selectivity in linear paraffins hydroconversion in 10-membered-ring pore zeolites

Pd/zeolite-catalyzed hydroconversion of n-hexadecane (n-C16) and n-heptane (n-C7) was studied for 10MR (ZSM-5, ZSM-22), 12MR (ZSM-12), and EMM-23 (21MR × 10MR) zeolites. The catalytic activity depended on the Brønsted acidity and the crystalline domain size. n-C16 hydroconversion benefited from short diffusion lengths in ZSM-5 nanosheets compared to bulk ZSM-5. In general, over-cracking is dominant in ZSM-5 with a cracked product distribution skewed to C4 products, to be explained by a snug fit of particular dibranched isomers at zeolite intersections. This effect is less pronounced for the 1D 10MR pores in ZSM-22, which lacks intersections. Although large pores in ZSM-12 offer relatively high activity, those in EMM-23 do not. Based on selectivity patterns, EMM-23 behaves like ZSM-5, probably because of the trilobe shape of its 21MR pores acting as 10MR pores. Only ZSM-12 offers operation in the ideal hydrocracking regime, in the sense of impediments neither by hydrogenation nor by diffusion. Faster intrazeolite diffusion of n-C7 in comparison to n-C16 leads to a higher yield of isomers for the nanostructured zeolites. Overall, the hydroconversion of the smaller alkane is more substantially impacted by variations in the crystalline zeolite domain size.</p

Shape selectivity in linear paraffins hydroconversion in 10-membered-ring pore zeolites

Pd/zeolite-catalyzed hydroconversion of n-hexadecane (n-C16) and n-heptane (n-C7) was studied for 10MR (ZSM-5, ZSM-22), 12MR (ZSM-12), and EMM-23 (21MR × 10MR) zeolites. The catalytic activity depended on the Brønsted acidity and the crystalline domain size. n-C16 hydroconversion benefited from short diffusion lengths in ZSM-5 nanosheets compared to bulk ZSM-5. In general, over-cracking is dominant in ZSM-5 with a cracked product distribution skewed to C4 products, to be explained by a snug fit of particular dibranched isomers at zeolite intersections. This effect is less pronounced for the 1D 10MR pores in ZSM-22, which lacks intersections. Although large pores in ZSM-12 offer relatively high activity, those in EMM-23 do not. Based on selectivity patterns, EMM-23 behaves like ZSM-5, probably because of the trilobe shape of its 21MR pores acting as 10MR pores. Only ZSM-12 offers operation in the ideal hydrocracking regime, in the sense of impediments neither by hydrogenation nor by diffusion. Faster intrazeolite diffusion of n-C7 in comparison to n-C16 leads to a higher yield of isomers for the nanostructured zeolites. Overall, the hydroconversion of the smaller alkane is more substantially impacted by variations in the crystalline zeolite domain size

Stable Fe/ZSM‑5 Nanosheet Zeolite Catalysts for the Oxidation of Benzene to Phenol

Fe/ZSM-5 nanosheet zeolites of varying thickness were synthesized with di- and tetraquaternary ammonium structure directing agents and extensively characterized for their textural, structural, and catalytic properties. Introduction of Fe³⁺ ions in the framework of nanosheet zeolites was slightly less effective than in bulk ZSM-5 zeolite. Steaming was necessary to activate all catalysts for N₂O decomposition and benzene oxidation. The higher the Fe content, the higher the degree of Fe aggregation was after catalyst activation. The degree of Fe aggregation was lower when the crystal domain size of the zeolite or the Fe content was decreased. These two parameters had a substantial influence on the catalytic performance. Decreasing the number of Fe sites along the <i>b</i>-direction strongly suppressed secondary reactions of phenol and, accordingly, catalyst deactivation. This together with the absence of diffusional limitations in nanosheet zeolites explains the much higher phenol productivity obtainable with nanostructured Fe/ZSM-5. Steamed Fe/ZSM-5 zeolite nanosheet synthesized using C_22‑6‑3·Br₂ (domain size in <i>b</i>-direction ∼3 nm) and containing 0.24 wt % Fe exhibited the highest catalytic performance. During the first 24 h on stream, this catalyst produced 185 mmol_phenol g^–1. Calcination to remove the coke deposits completely restored the initial activity

The important role of rubidium hydroxide in the synthesis of hierarchical ZSM-5 zeolite using cetyltrimethylammonium as structure-directing agent

Hierarchical ZSM‐5 zeolite with uniform mesopores was synthesized with a simple cetyltrimethylammonium (CTA+) template, which acted as a bifunctional surfactant in a RbOH‐based alkaline synthesis gel. Rb+ plays a key role in obtaining uniform mesopores within ZSM‐5 crystals. The structural, textural properties and the acidity were characterized by XRD, Ar physisorption, TEM, as well as CO IR and 27Al MAS NMR spectroscopy. These data point to partial retention of the initial mesoscale ordered texture of the precursor in the final zeolite. These textural properties result in a strongly improved catalytic performance in the methanol conversion reaction compared to bulk zeolite

Reversible nature of coke formation on Mo/ZSM-5 methane dehydroaromatization catalysts

Non-oxidative dehydroaromatization of methane over Mo/ZSM-5 zeolite catalysts is a promising reaction for the direct conversion of abundant natural gas into liquid aromatics. Rapid coking deactivation hinders the practical implementation of this technology. Herein, we show that catalyst productivity can be improved by nearly an order of magnitude by raising the reaction pressure to 15 bar. The beneficial effect of pressure was found for different Mo/ZSM-5 catalysts and a wide range of reaction temperatures and space velocities. High-pressure operando X-ray absorption spectroscopy demonstrated that the structure of the active Mo-phase was not affected by operation at elevated pressure. Isotope labeling experiments, supported by mass-spectrometry and 13 C nuclear magnetic resonance spectroscopy, indicated the reversible nature of coke formation. The improved performance can be attributed to faster coke hydrogenation at increased pressure, overall resulting in a lower coke selectivity and better utilization of the zeolite micropore space

One-Step Synthesis of Hierarchical ZSM‑5 Using Cetyltrimethylammonium as Mesoporogen and Structure-Directing Agent

Hierarchical ZSM-5 zeolite is hydrothermally synthesized in a single step with cetyltrimethylammonium (CTA) hydroxide acting as mesoporogen and structure-directing agent. Essential to this synthesis is the replacement of NaOH with KOH. An in-depth solid-state NMR study reveals that, after early electrostatic interaction between condensed silica and the head group of CTA, ZSM-5 crystallizes around the structure-directing agent. The crucial aspect of using KOH instead of NaOH lies in the faster dissolution of silica, thereby providing sufficient nutrients for zeolite nucleation. The hierarchical ZSM-5 zeolite contains mesopores and shows excellent catalytic performance in the methanol-to-hydrocarbons reaction

A dual-templating synthesis strategy to hierarchical ZSM-5 zeolites as efficient catalysts for the methanol-to-hydrocarbons reaction

A novel dual-templating synthesis strategy is presented to obtain hierarchical ZSM-5 zeolite using a combination of known structure-directing agents for ZSM-5 synthesis and C16H33-[N+-methylpiperidine] (C16MP) as mesoporogen. C16MP is a cheap surfactant, which can be obtained in a single step by alkylation of N-methylpiperidine. The zeolite materials were extensively characterized for their textural and acidic properties and evaluated on the basis of their ability to convert methanol to hydrocarbons. Bulk and nanosheet (di-quaternary ammonium surfactant) ZSM-5 zeolites served as reference materials. Hierarchical ZSM-5 zeolite can be obtained in this way with diethylamine, n-propylamine, 1,4-diaminobutane, 1,6-diaminohexane. In particular, the combination with diethylamine afforded a material that displayed similar performance in the methanol-to-hydrocarbons reaction as nanosheet ZSM-5. The optimum ZSM-5 zeolite is highly crystalline, contains a large mesopore volume and few silanol groups and external Brønsted acid sites, which contributes to the low rate of deactivation