Display omitted
•Scale-dependent fractal property is confirmed for cement-based porous materials.•Micro-fractal and macro-fractal regions are identified for whole pore size range.•Upper pore size for ...micro-fractal range is around 30nm and nearly constant.•Curing condition and GGBS have impact on fractal properties of materials.
This study investigates the surface fractal dimensions (SFDs) of pore structure of cement pastes and mortars with/without ground granulated blast-furnace slag (GGBS) incorporated into binder. The samples were subject to water curing and sealed curing. The fractal dimensions of samples are determined by Zhang’s model (Ind Eng Chem Res, 34 (1995):1383–1386) on the basis of mercury intrusion porosimetry (MIP) data. The results confirm the scale-dependent property of fractal dimension of pore structures and the micro-fractal, transition and macro-fractal regions are identified for all samples. The upper pore size range for micro-fractal regions is around 30nm, the transition regions cover 0.5–2 magnitude orders of pore size and macro fractal regions cover 1.5–3 magnitude orders. Both curing conditions and GGBS in binder have impact on the fractal properties of pore structure, and samples incorporating GGBS have substantially larger values for micro-fractal regions.
The outbreak of corona virus disease 2019 (Covid-19) imposes a major challenge in managing patients undergoing surgical operation. In this study, we analyzed clinical and transmission features of 25 ...cases of Covid-19 from a single thoracic department, including 13 patients and 12 health care staff. There were 13 males and 12 females. The median age of the patients was 61 (range: 51 to 69) years. The median age of the health care staff was 35 (range: 22 to 51) years. By the end of follow-up date (Mar. 3, 2020), there were 16 non-severe cases (64%) and 9 severe cases (36%), 5 cases were dead (20%). Nineteen (76%) of the infected cases were confirmed by SARS-CoV-2 nucleic acid test, the rest were clinically diagnosed as suspected Covid-19 cases, and 19 (76%) of the infected cases had positive exposure history. We found that COPD was significantly associated with severity and death (P=0.040, and P=0.038, respectively), and chest operation was significantly associated with death for Covid-19 patients (P=0.039). A potential "super spreader" may be the source of the transmission before the implementation of quarantine and comprehensive protection. It was concluded that Covid-19 is associated with poor prognosis for patients undergoing thoracic operation, especially for those with COPD. Implementation of comprehensive protective measures is important to control nosocomial infection.
The aeolian loess deposits in northeastern China have substantial potential for reconstructing the paleoclimate in the East Asian monsoon boundary zone. Identifying the source of the aeolian dust is ...crucial to interpret the paleo‐proxies recorded in the loess deposits in northeastern China; however, traditional geochemical tracers such as Nd and Sr isotopes cannot discriminate between the potential source areas, that is, the Otindag Sandy Land, Horqin Sandy Land, and Hulun Buir Sandy Land regions. In this study, the (234U/238U) activity ratio is used to constrain the provenance of the loess deposits in northeastern China. The (234U/238U) of the studied loess‐paleosol sequences (from 0.935 to 0.910) decreases with increasing depositional age (from 10 to ∼1,000 ka), which is consistent with predictions from uranium isotope comminution age model. A derived (234U/238U) of 0.935 ± 0.003 for the newly deposited loess (zero depositional age) is most similar to that of the Otindag Sandy Land positioned at a proximal upwind direction, suggesting that the Otindag Sandy Land is the most likely source of the aeolian dust that formed the loess deposits in northeastern China. A transportation time of 432 ± 65 ka was calculated for these deposits, indicating extensive mixing of the fine dust in the source regions, which could partially explain the relative homogeneity of loess deposits in northeastern China. The transportation time longer than several glacial‐interglacial cycles suggests that reconstructions of regional paleoclimate on orbital timescales should be viewed with caution because the potential influence of climatic changes could largely be buffered.
Plain Language Summary
The activity ratio of the uranium isotopes (234U and 238U) in fine‐grained particles can be used to determine the “comminution age”, or the amount of time since the production of fine sediment particles (≤50 μm) from the breakdown of bedrock by weathering. The (234U/238U) activity ratio provides a new approach to track the age and origin of dust particles. In this study, we measure the (234U/238U) composition of the loess deposits in northeastern China and surface sand samples in potential source areas to better understand the transport of aeolian dust in the region. We find that the Otindag Sandy Land, which is in the proximal upwind direction, is the main source region for the loess deposits in northeastern China and that the dust materials have been resided in the source region for around 432 ± 65 thousand years before aeolian transport and deposition. Our results shed light on the transport and depositional history of loess in northeastern China and provide valuable information for reconstructing paleoclimate using the loess deposits in this region.
Key Points
The (234U/238U) activity ratio of a loess sequence in northeastern China is consistent with a uranium isotope comminution age model
Loess deposits found in northeastern China have a long residence time of 432 ± 65 ka in the source regions
The Otindag Sandy Land in the proximal upwind direction is the main source region for the studied loess sequence
Absorptive root traits show remarkable cross-species variation, but major root trait dimensions across species have not been defined.
We sampled first-order roots and measured 14 root traits for 96 ...angiosperm woody species from subtropical China, including root diameter, specific root length, stele diameter, cortex thickness, root vessel size and density, mycorrhizal colonization rate, root branching intensity, tissue density, and concentrations of carbon and nitrogen (N).
Root traits differed in the degree of variation and phylogenetic conservatism, but showed predictable patterns of cross-trait coordination. Root diameter, cortex thickness and stele diameter displayed high variation across species (coefficient of variation (CV) = 0.51–0.69), whereas the stele:root diameter ratio and N showed low variation (CV < 0.32). Root diameter, cortex thickness and stele diameter showed a strong phylogenetic signal across species, whereas root branching traits did not, and these two sets of traits were segregated onto two nearly orthogonal (independent) principal component analysis (PCA) axes.
Two major dimensions of root trait variation were found: a diameter-related dimension potentially integrating root construction, maintenance, and persistence with mycorrhizal colonization, and a branching architecture dimension expressing root plastic responses to the environment. These two dimensions may offer a promising path for better understanding root trait economics and root ecological strategies world-wide.
In order to mitigate the rapid grain growth, a sintered ferrite magnet exhibiting stable characteristics was successfully synthesized. M-type strontium ferrite Sr1-xSmxFe12-xCoxO19 (x = 0.00, 0.01, ...0.02, 0.03, 0.04, 0.05 and 0.10) was synthesized via a low-temperature co-firing method, incorporating an appropriate quantity of Bi2O3 and CuO as additives within the solid-phase reaction process. The magnetic and electrical properties of the resulting composites were meticulously examined, and X-ray diffraction (XRD) analysis was performed for structural characterization. The findings reveal that a pure hexagonal strontium phase is achieved consistently when the substitution level, x, remains below 0.5. With an increase in the substitution level, a heterogeneous phase α-Fe2O3 becomes apparent within the phase structure. Upon introducing doping elements, the subtle incorporation of SmCo (x ≤ 0.02) enhances the saturation magnetization, remanent magnetization, and coercivity of the composite material. Moreover, the resistances of grain and grain boundary (Rg, Rgb) have been downscaled from 1.856 × 106Ω and 3.61 × 106Ω to 3.182 × 104Ω and 4.37 × 105Ω respectively. Consequently, the Sr1-xSmxFe12-xCoxO19 ferrite sintered under low-temperature conditions demonstrates outstanding electromagnetic characteristics, presenting a viable option for materials in microwave device applications.
Introduction
Alors que des données probantes montrent que certains travailleurs de première ligne et travailleurs essentiels ont augmenté leur consommation d’alcool pendant la pandémie de COVID-19, ...cette question n’a pas été étudiée au Canada.
Méthodologie
À l’aide des données de l’Enquête sur la COVID-19 et la santé mentale (ECSM) de 2020, nous avons calculé la prévalence pondérée de la consommation autodéclarée accrue d’alcool et de la forte consommation épisodique d’alcool et les intervalles de confiance à 95 % correspondants pour trois groupes de population : travailleurs de première ligne, travailleurs essentiels et travailleurs autres que de première ligne ou essentiels. Nous avons effectué une analyse de régression logistique pour étudier les associations entre les déterminants sociaux de la santé, la santé mentale et la consommation d’alcool pour chaque groupe.
Résultats
La prévalence de la consommation accrue d’alcool et celle de la forte consommation épisodique d’alcool au cours du dernier mois ne différaient pas entre les travailleurs de première ligne, les travailleurs essentiels et les autres travailleurs. Au sein des trois groupes, les personnes ne s’identifiant pas comme appartenant à un groupe racisé avaient des probabilités supérieures dans les deux résultats. Le fait d’avoir obtenu un résultat positif au dépistage du trouble d’anxiété généralisée ou du trouble de l’humeur était significativement associé à une consommation accrue d’alcool chez les trois groupes. Chez les travailleurs de première ligne et les travailleurs essentiels, les personnes de genre féminin étaient beaucoup moins susceptibles que celles de genre masculin de faire état d’une forte consommation épisodique d’alcool. Chez les travailleurs essentiels seulement, on a établi une association significative entre le fait de vivre dans une région rurale et une probabilité moindre de consommation accrue d’alcool, ainsi qu’une association significative entre le fait d’avoir obtenu un résultat positif au dépistage du trouble de stress post-traumatique et une probabilité plus élevée de forte consommation épisodique d’alcool. Chez les travailleurs de première ligne seulement, on a établi une association significative entre le fait de vivre dans une région rurale et une probabilité moindre de forte consommation épisodique d’alcool.
Conclusion
Même si les travailleurs de première ligne et les travailleurs essentiels ne se sont pas révélés plus susceptibles de faire état d’une consommation accrue d’alcool et d’une forte consommation épisodique d’alcool que les autres travailleurs, des différences ont été établies dans les facteurs associés à la consommation d’alcool. Ces résultats montrent l’importance d’analyser chaque groupe séparément pour obtenir des données aptes à orienter les stratégies ciblées de prévention.
CO2 reduction to carbon feedstocks using heterogeneous photocatalysis technique has been deemed as an attractive means of addressing both deteriorating greenhouse effect and depletion of fossil ...fuels. Nevertheless, deficiency of accessible active sites on the catalyst surface, low CO2 adsorption rate, and short carrier lifetime retard the photocatalytic CO2 conversion into hydrocarbon fuels. In this study, the controllable construction of spatially separated directional charge transport pathways over multilayered heterostructured transition metal chalcogenides (TMCs) based photosystems for high‐performance photocatalytic CO2‐to‐syngas conversion are shown. In this scenario, ultrathin non‐conjugated insulating poly(diallyl‐dimethyl‐ammonium chloride) (PDDA) layer are intercalated in‐between TMCs and layered double hydroxide (LDH) and serve as an efficient electron transfer mediator, whilst LDH functions as a hole‐withdrawing regulator, both of which synergistically foster the spatial vectorial charge migration/separation over TMCs, thus endowing the TMCs/PDDA/LDH heterostructures with significantly boosted visible‐light‐driven photoactivity toward CO2 conversion into syngas. This study can inspire sparkling new ideas to realize fine tuning of charge motion for stimulating solar‐to‐fuel conversion.
Ultrathin non‐conjugated insulating poly(diallyl‐dimethyl‐ammonium chloride) (PDDA) serves as an efficient electron transfer mediator, and simultaneously layered double hydroxide (LDH) functions as a hole‐withdrawing regulator, both of which synergistically contributes to the spatially separated bi‐directional charge transfer pathways over transition metal chalcogenides toward significantly boosted CO2 photoreduction catalysis under visible light irradiation.
In halophytic plants, the high-affinity potassium transporter HKT gene family can selectively uptake K＋ in the presence of toxic concentrations of Na＋. This has so far not been well examined in ...glycophytic crops. Here, we report the characterization of SbHKTI;4, a member of the HKT gene family from Sorghum bicolor. Upon Na＋ stress, SbHKT1;4 expression was more strongly upregulated in salt-tolerant sorghum accession, correlating with a better balanced Na＋/ K＋ ratio and enhanced plant growth. Heterogeneous expression analyses in mutants of Saccharomyces cerevisiae and Arabidopsis thaliana indicated that overexpressing SbHKT1;4 resulted in hypersensitivity to Na＋ stress, and such hypersensitivity could be alleviated with the supply of elevated levels of K＋, implicating that SbHKT1;4 may mediate K＋ uptake in the presence of excessive Na＋. Further electrophysiological evidence demonstrated that SbHKT1;4 could transport Na＋ and K＋ when expressed in Xenopus laevis oocytes. The relevance of the finding that SbHKTI;4 functions to maintain optimal Na＋/K＋ balance under Na＋ stress to the breeding of salt-tolerant glycophytic crops is discussed.
The effect of procyanidin A2 (PCA2) and its major colonic metabolite 3-(4-hydroxyphenyl)propionic acid (HPPA) on the suppression of macrophage foam cell formation, and underlying mechanism, were ...investigated for the first time. The results showed that 12.5 μg mL
−1
PCA2 and HPPA significantly reduced cellular lipid accumulation and inhibited foam cell formation. HPPA promoted macrophage cholesterol efflux by up-regulating mRNA expressions of ABCA1 and SR-B1, while PCA2 significantly increased SR-B1 and LXR-α mRNA expression levels. Moreover, PCA2 and HPPA significantly lowered the elevated levels of CD36 mRNA expression in ox-LDL-treated macrophage cells. Besides these, the ox-LDL-induced cellular oxidative stress and inflammation was also restricted by PCA2 and HPPA treatment
via
nuclear factor kappa-B pathways. In conclusion, PCA2 and its major microbial metabolite, HPPA, inhibited the conversion of macrophage into foam cells
via
regulating cellular lipid metabolism and suppressing cellular oxidative stress and inflammation.
PCA2 and its major microbial metabolite HPPA inhibited macrophage foam cell formation, which may be due to regulating ABCA1, SR-B1 and CD36 expression, and restricted cellular oxidative stress and inflammation via NF-κB pathway.
The rational design of the directional charge transfer channel represents an important strategy to finely tune the charge migration and separation in photocatalytic CO2‐to‐fuel conversion. Despite ...the progress made in crafting high‐performance photocatalysts, developing elegant photosystems with precisely modulated interfacial charge transfer feature remains a grand challenge. Here, a facile one‐pot method is developed to achieve in situ self‐assembly of Pd nanocrystals (NYs) on the transition metal chalcogenide (TMC) substrate with the aid of a non‐conjugated insulating polymer, i.e., branched polyethylenimine (bPEI), for photoreduction of CO2 to syngas (CO/H2). The generic reducing capability of the abundant amine groups grafted on the molecular backbone of bPEI fosters the homogeneous growth of Pd NYs on the TMC framework. Intriguingly, the self‐assembled TMCs@bPEI@Pd heterostructure with bi‐directional spatial charge transport pathways exhibit significantly boosted photoactivity toward CO2‐to‐syngas conversion under visible light irradiation, wherein bPEI serves as an efficient hole transfer mediator, and simultaneously Pd NYs act as an electron‐withdrawing modulator for accelerating spatially vectorial charge separation. Furthermore, in‐depth understanding of the in situ formed intermediates during the CO2 photoreduction process are exquisitely probed. This work provides a quintessential paradigm for in situ construction of multi‐component heterojunction photosystem for solar‐to‐fuel energy conversion.
Non‐conjugated insulating polymer encapsulation and in‐situ growth of metal nanocrystal synergistically contribute to the spatially separated bi‐directional charge transfer pathways toward boosted solar CO2‐to‐syngas conversion.
PDF
