Nonradiating electromagnetic configurations in nanostructures open new horizons for applications due to two essential features: a lack of energy losses and invisibility to the propagating ...electromagnetic field. Such radiationless configurations form a basis for new types of nanophotonic devices, in which a strong electromagnetic field confinement can be achieved together with lossless interactions between nearby components. In our work, we present a new design of free-standing disk nanoantennas with nonradiating current distributions for the optical near-infrared range. We show a novel approach to creating nanoantennas by slicing III–V nanowires into standing disks using focused ion-beam milling. We experimentally demonstrate the suppression of the far-field radiation and the associated strong enhancement of the second-harmonic generation from the disk nanoantennas. With a theoretical analysis of the electromagnetic field distribution using multipole expansions in both spherical and Cartesian coordinates, we confirm that the demonstrated nonradiating configurations are anapoles. We expect that the presented procedure of designing and producing disk nanoantennas from nanowires becomes one of the standard approaches to fabricating controlled chains of standing nanodisks with different designs and configurations. These chains can be essential building blocks for new types of lasers and sensors with low power consumption.
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IJS, KILJ, NUK, PNG, UL, UM
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•MIL-100(Al), Cu3(BTC)2·(H2O)3, UiO-66 were studied in Knoevenagel condensation reaction.•Activity of metal carboxylates depends on the “M+n–O2− Lewis acid–base” pair.•The strength of ...interaction between metal and oxygen was estimated from ionic covalent parameter.•Amount of NH2 groups in UiO-66-NH2 affects the basicity and catalytic properties.
Effect of basicity of porous metal-carboxylates, such as MIL-100(Al), Cu3(BTC)2·(H2O)3, UiO-66 and amino-modified UiO-66 materials (UiO-66-NH2) on their catalytic performance, was studied in the Knoevenagel condensation of benzaldehyde with malononitrile to 2-benzylidenemalononitrile. According to physicochemical studies, the strength of the basic sites for MIL-100(Al), Cu3(BTC)2·(H2O)3, UiO-66 was in the range of 830–839kJ/mol, while the amount of basic sites decreased in the order MIL-100(Al)>Cu3(BTC)2·(H2O)3>UiO-66. The insertion of NH2 groups into the UiO-66 framework led to an increase in the strength of basic sites from 839 to 867kJ/mol. The catalytic activity of metal carboxylates correlated with the amount of basic sites and the strength of the interaction between metal and oxygen in the “M+n–O2− Lewis acid–base” pair, which was estimated from ionic covalent parameters. The activity of the UiO-66-NH2 materials was higher than that of UiO-66.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
Zeolitic imidazolate frameworks (ZIFs) have been extensively examined for their potential in acid-base catalysis. Many studies have demonstrated that ZIFs possess unique structural and ...physicochemical properties that allow them to demonstrate high activity and yield products with high selectivity. Herein, we highlight the nature of ZIFs in terms of their chemical formulation and the textural, acid-base, and morphological properties that strongly affect their catalytic performance. Our primary focus is the application of spectroscopic methods as instruments for analyzing the nature of active sites because these methods can allow an understanding of unusual catalytic behavior from the perspective of the structure-property-activity relationship. We examine several reactions, such as condensation reactions (the Knoevenagel condensation and Friedländer reactions), the cycloaddition of CO
to epoxides, the synthesis of propylene glycol methyl ether from propylene oxide and methanol, and the cascade redox condensation of 2-nitroanilines with benzylamines. These examples illustrate the broad range of potentially promising applications of Zn-ZIFs as heterogeneous catalysts.
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IZUM, KILJ, NUK, PILJ, PNG, SAZU, UL, UM, UPUK
•A family of isoreticular MOF based on the UiO-66 structure was synthesized from the two linker ligands.•Effect of NH2- and NO2-groups in linker ligands on acid–base and catalytic properties was ...studied.•Acetalization of benzaldehyde with methanol was used for analysis of Lewis acidity of UiO-66 materials.
A family of isoreticular metal-organic frameworks (MOFs), based on the UiO-66 structure, were synthesized from the two linker ligands containing electron-donating NH2-groups (2-amino-benzenedicarboxylic acid (H2N-H2BDC)) and electron-withdrawing NO2-groups (2-nitro-benzenedicarboxylic acid (O2N-H2BDC)). The catalytic performance of these materials was investigated with a combination of physicochemical and catalytic approaches in acetalization of benzaldehyde with methanol. The investigation of basicity and Lewis acidity was done by IR spectroscopy using CDCl3 and 5-nonanone as probe molecules, respectively. The combination of physicochemical and catalytic investigations demonstrates that acid–base and catalytic properties of these materials depend on amount and type of functional groups presented in the linker units. Insertion of electron-donating NH2-groups into linker ligand leads to increase in the strength of basic sites in contrast to electron-withdrawing NO2-groups. The strength of Lewis acid sites decreases in order of UiO-66-NO2>UiO-66>UiO-66-NH2, that leads to the decrease in their catalytic activity in acetalization of benzaldehyde with methanol in the same order.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
This paper discusses the mechanism of montmorillonite structural alteration and modification of bentonites’ properties (based on samples from clay deposits Taganskoye, Kazakhstan and Mukhortala, ...Buriatia) under thermochemical treatment (treatment with inorganic acid solutions at different temperatures, concentrations and reaction times). Treatment conditions were chosen according to those accepted in chemical industry for obtaining acid modified clays as catalysts or sorbents. Also, more intense treatment was carried out to simulate possible influence at the liquid radioactive site repositories. A series of methods was used: XRD, FTIR, ICP-AES, TEM, nitrogen adsorption, and particle size analysis. It allowed revealing certain processes: transformation of montmorillonite structure which appears in the leaching of interlayer and octahedral cations and protonation of the interlayer and –OH groups at octahedral sheets. In turn, changes in the structure of the 2:1 layer of montmorillonite and its interlayer result in significant alterations in the properties: reduction of cation exchange capacity and an increase of specific surface area. Acid treatment also leads to a redistribution of particle sizes and changes the pore system. The results of the work showed that bentonite clays retain a significant portion of their adsorption properties even after a prolonged and intense thermochemical treatment (1 M HNO3, 60 °C, 108 h).
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CEKLJ, IZUM, KILJ, NUK, PILJ, PNG, SAZU, UL, UM, UPUK
Colorectal cancer (CRC) displays a complex pattern of inheritance. It is postulated that much of the missing heritability of CRC is enshrined in high-impact rare alleles, which are mechanistically ...and clinically important. In this study, we assay the impact of rare germline mutations on CRC, analysing high-coverage exome sequencing data on 1,006 early-onset familial CRC cases and 1,609 healthy controls, with additional sequencing and array data on up to 5,552 cases and 6,792 controls. We identify highly penetrant rare mutations in 16% of familial CRC. Although the majority of these reside in known genes, we identify POT1, POLE2 and MRE11 as candidate CRC genes. We did not identify any coding low-frequency alleles (1-5%) with moderate effect. Our study clarifies the genetic architecture of CRC and probably discounts the existence of further major high-penetrance susceptibility genes, which individually account for >1% of the familial risk. Our results inform future study design and provide a resource for contextualizing the impact of new CRC genes.
It is speculated that genetic variants are associated with differential responses to nutrients (known as gene-diet interactions) and that these variations may be linked to different cancer risks. In ...this review, we critically evaluate the evidence across 314 meta-analyses of observational studies and randomized controlled trials of dietary risk factors and the five most common cancers (breast, lung, prostate, colorectal, and stomach). We also critically evaluate the evidence across 13 meta-analyses of observational studies of gene-diet interactions for the same cancers. Convincing evidence for association was found only for the intake of alcohol and whole grains in relation to colorectal cancer risk. Three nutrient associations had highly suggestive evidence and another 15 associations had suggestive evidence. Among the examined gene-diet interactions, only one had moderately strong evidence.
Abstract
Background
Vitamin D deficiency is highly prevalent across the globe. Existing studies suggest that a low vitamin D level is associated with more than 130 outcomes. Exploring the causal role ...of vitamin D in health outcomes could support or question vitamin D supplementation.
Methods
We carried out a systematic literature review of previous Mendelian-randomization studies on vitamin D. We then implemented a Mendelian Randomization–Phenome Wide Association Study (MR-PheWAS) analysis on data from 339 256 individuals of White British origin from UK Biobank. We first ran a PheWAS analysis to test the associations between a 25(OH)D polygenic risk score and 920 disease outcomes, and then nine phenotypes (i.e. systolic blood pressure, diastolic blood pressure, risk of hypertension, T2D, ischaemic heart disease, body mass index, depression, non-vertebral fracture and all-cause mortality) that met the pre-defined inclusion criteria for further analysis were examined by multiple MR analytical approaches to explore causality.
Results
The PheWAS analysis did not identify any health outcome associated with the 25(OH)D polygenic risk score. Although a selection of nine outcomes were reported in previous Mendelian-randomization studies or umbrella reviews to be associated with vitamin D, our MR analysis, with substantial study power (>80% power to detect an association with an odds ratio >1.2 for per standard deviation increase of log-transformed 25OHD), was unable to support an interpretation of causal association.
Conclusions
We investigated the putative causal effects of vitamin D on multiple health outcomes in a White population. We did not support a causal effect on any of the disease outcomes tested. However, we cannot exclude small causal effects or effects on outcomes that we did not have enough power to explore due to the small number of cases.
The role of urate in cardiovascular diseases (CVDs) has been extensively investigated in observational studies; however, the extent of any causal effect remains unclear, making it difficult to ...evaluate its clinical relevance.
A phenome-wide association study (PheWAS) together with a Bayesian analysis of tree-structured phenotypic model (TreeWAS) was performed to examine disease outcomes related to genetically determined serum urate levels in 339,256 unrelated White British individuals (54% female) in the UK Biobank who were aged 40-69 years (mean age, 56.87; SD, 7.99) when recruited from 2006 to 2010. Mendelian randomization (MR) analyses were performed to replicate significant findings using various genome-wide association study (GWAS) consortia data. Sensitivity analyses were conducted to examine possible pleiotropic effects on metabolic traits of the genetic variants used as instruments for urate. PheWAS analysis, examining the association with 1,431 disease outcomes, identified 13 distinct phecodes representing 4 disease groups (inflammatory polyarthropathies, hypertensive disease, circulatory disease, and metabolic disorders) and 9 disease outcomes (gout, gouty arthropathy, pyogenic arthritis, essential hypertension, coronary atherosclerosis, ischemic heart disease, chronic ischemic heart disease, myocardial infarction, and hypercholesterolemia) that were associated with genetically determined serum urate levels after multiple testing correction (p < 3.35 × 10-4). TreeWAS analysis, examining 10,750 ICD-10 diagnostic terms, identified more sub-phenotypes of cardiovascular and cerebrovascular diseases (e.g., angina pectoris, heart failure, cerebral infarction). MR analysis successfully replicated the association with gout, hypertension, heart diseases, and blood lipid levels but indicated the existence of genetic pleiotropy. Sensitivity analyses support an inference that pleiotropic effects of genetic variants on urate and metabolic traits contribute to the observational associations with CVDs. The main limitations of this study relate to possible bias from pleiotropic effects of the considered genetic variants and possible misclassification of cases for mild disease that did not require hospitalization.
In this study, high serum urate levels were found to be associated with increased risk of different types of cardiac events. The finding of genetic pleiotropy indicates the existence of common upstream pathological elements influencing both urate and metabolic traits, and this may suggest new opportunities and challenges for developing drugs targeting a common mediator that would be beneficial for both the treatment of gout and the prevention of cardiovascular comorbidities.
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DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
The effect of acid modification of a natural montmorillonite clay (MM) by HNO3 on the catalytic properties of MM from Dash-Salakhlinsk (Kazakhstan) has been investigated in the synthesis of solketal ...from glycerol and acetone in solvent free and acetonitrile media. HNO3 concentration allowed to control the chemical composition, the surface acidity, the porous structure of the acid-activated MMs and their catalytic performance. The main reaction product was solketal with 86.6–98% selectivity. Conversion of glycerol depended on the Brønsted acidity. The most active sample, namely, MM activated with 0.5mol/dm3 HNO3, showed good reusability for 3 catalyst cycles.
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•Natural montmorillonite (MM) was modified by 0.125–3.0mol/dm3 HNO3.•The concentration of HNO3 affected the textural and acid-base properties.•Condensation of glycerol with acetone over the acid-activated clays was investigated.•Effect of acidic modification of MM on reaction rate was investigated.•Catalytic activity of catalyst depended on the amount of Brønsted acid sites.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZRSKP
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