Search

A stereodivergent synthesis of β- and α-O-glycosides using 3-O-quinaldoyl glucals was developed by palladium catalysis at 60 and 110 °C respectively. Various alcohols, monosaccharides, and amino acid were glycosylated to form β- and α- products in good yields with high stereoselectivity. Mechanistic studies indicated no classic Pd–N (quinoline) coordination, but π–π stacking interactions promoted the anomeric stereodiversity. The practicality was demonstrated by glycosylating natural products/drugs and synthesizing a complex tetrasaccharide.

We experimentally investigated the coalescence-induced droplet-particle jumping phenomenon on a submillimeter scale in symmetric and asymmetric particle arrangements with poly(methyl methacrylate) (PMMA) particles and stainless steel (SS) particles. Coalescence-induced droplet-particle jumping exhibited excellent capability and interesting behavior for both droplet jumping enhancement and particle transport. The particle increased the normalized droplet jumping velocity from 0.250 for no particle case to 0.315 and 0.320 for symmetric and asymmetric particle cases. Compared with similar-sized macrostructures fixed between droplets, better jumping performance with particles may be attributed to avoiding the work of adhesion during droplet-macrostructure separation. Besides, all particles always sunk at the bottom in the symmetric cases, while the stick mode for PMMA particles and sink, wander, and jet modes for SS particles appeared in the asymmetry cases. We revealed that the asymmetric particle arrangement induces an unbalanced surface tension force, which may provide a driving force in the vertical direction. Additionally, a small enough resistive force caused by hydrophobic particles is another necessary condition for the wonder and jet mode. Finally, we realized a significantly superior particle transport in the asymmetric SS particle cases with maximum particle height reaching ∼2.1 mm, ∼12.4 times the particle radius, the most significant vertical self-propelled transport distance currently.

The MYB4 transcription factor family regulates plant traits. However, their overexpression often results in undesirable side effects like growth reduction. We have reported a green tea (Camellia sinensis) MYB4 transcription factor (CsMYB4) that represses the phenylpropanoid and shikimate pathways and stunts plant growth and development. In the current study, we observed that in CsMYB4atransgenic tobacco (Nicotiana tabacum) plants, primary metabolism was altered, including sugar and amino acid metabolism, which demonstrated a pleiotropic regulation by CsMYB4a. The CsMYB4atransgenic tobacco plants had improved drought tolerance, which correlated to alterations in carbohydrate metabolism and an increase in proline content, as revealed by metabolic profiling and transcriptomic analysis. To mitigate the undesirable repressive side effects on plant traits, including dwarfism, shrunken leaves, and shorter roots of CsMYB4atransgenic plants, we deleted the C4 domain of CsMYB4a to obtain a CsMYB4a-DC4 variant and then overexpressed it in transgenic plants (CsMYB4a-DC4). These CsMYB4a-DC4 plants displayed a normal growth and had improved drought tolerance. Metabolite analysis demonstrated that the contents of carbohydrates and proline were increased in these transgenic plants. Our findings suggest that  an approriate modification of TFs can generate novel crop traits, thus providing potential agricultural benefits and expanding its application to various crops.

Inhibiting the Leidenfrost effect has drawn extensive attention due to its detrimental impact on heat dissipation in high-temperature industrial applications. Although hierarchical structures have improved the Leidenfrost point to over 1000 °C, the current performance of single-scale structures remains inadequate. Herein, we present a facile high-temperature treatment method to fabricate superhydrophilic nickel foams that demonstrate ultrafast droplet permeation within tens of milliseconds, elevating the Leidenfrost point above 500 °C. Theoretical analysis based on the pressure balance suggests that these remarkable features arise from the superhydrophilic property, high porosity, and large pore diameter of nickel foams that promote capillary wicking and vapor evacuation. Compared to solid nickel surfaces with a Leidenfrost temperature of approximately 235 °C, nickel foams nucleate boiling at high superheat, triggering an order of magnitude higher heat flux. The effects of the pore diameter and surface temperature on droplet permeation behaviors and heat transfer characteristics are also elucidated. The results indicate that droplet permeation is dominated by inertial and capillary forces at low and high superheat, respectively, and moderate pore diameters are more conducive to facilitating droplet permeation. Furthermore, our heat transfer model reveals that pore diameter plays a negligible role in the heat flux at high surface temperatures due to the trade-off between effective thermal conductivity and specific surface area. This work provides a new strategy to address the Leidenfrost effect by metal foams, which may promise great potential in steel forging and nuclear reactor safety.

Based on the energy conservation approach, this study develops a universal model to predict the maximum spreading factor of liquid droplet impact on a smooth solid surface. Validated with the present simulations and experiments in the literature, this model effectively overcomes the limitation of previous models in the viscous regime and greatly reduces the computing errors from over 30% to below 6%. It is demonstrated that the underestimated maximum spreading factor by previous models results from the overestimation of viscous dissipation. By replacing the conventional model of spreading time, tm= 8D0/3U0, with a more precise one, tm= 1.47τiWe–0.44, the formulation to compute the viscous dissipation of entire spreading is improved. Finally, we examine the applicability of present model in the capillary regime and good performance is also shown.

Single measurements of waist circumference (WC) can predict the incident hypertension, while dynamic change patterns of WC during young adulthood and their association with the incidence of hypertension are poorly demonstrated. This study aimed to identify the longitudinal WC trajectories during young adulthood and explore their association with the risk of incident hypertension. We utilized the data from the China Health and Nutrition Survey (1993–2015) and included 6604 participants aged 18–50 years with repeated WC measurements of 3–8 times and information on incident hypertension. The group-based trajectory model was used to identify WC trajectories. Cox proportional hazard model was conducted to evaluate the association of WC trajectories with the risk of incident hypertension. We identified four distinct WC trajectories during young adulthood. Participants with the low-increasing and the moderate-increasing trajectories had increasing but normal WC, while those with the high-increasing and the sharp-increasing trajectories developed from non-abdominal obesity to abdominal obesity. Compared with the low-increasing trajectory, the adjusted hazard ratios (95% confidence intervals) were 1.48 (1.16–1.89), 2.50 (1.84–3.40), and 3.86 (2.40–6.21) for the moderate-increasing, the high-increasing, and the sharp-increasing trajectories, respectively. After further excluding participants with obesity at baseline, this association did not alter substantially. The gender-specific trajectory analyses yielded similar results. WC trajectories during young adulthood were significantly associated with the risk of incident hypertension in Chinese. Moreover, even the increasing WC trajectory within the normal range during young adulthood might increase the risk of hypertension.

The merits of ABO3-type perovskite oxides as catalysts for volatile organic compounds (VOCs) combustion are that the redox capability of transition metal elements in their lattice structure can be well tailored through a facile doping strategy. In particular, La-Sr-Co-Fe-O perovskite-type oxides possess excellent tunable physicochemical properties, making them an ideal platform for promising prospects in VOCs combustion. This work synthesized a series of La1-xSrxCo1-yFeyO3(x = 0, 0.3, 0.5, 0.8; y = 0, 0.2, 0.5) perovskites and analyzed their reaction kinetics on toluene combustion. Among all the catalysts, La0.5Sr0.5Co0.8Fe0.2O3-δ(LSCF) showed a remarkable catalytic activity towards the toluene oxidation with T90of 270 °C at a weight hourly space velocity (WSHV) of 30000 mL·g−1·h−1and apparent activation energy (Ea) of 44.76 kJ·mol−1and obtained the superior stability. Based on the characterizations and analysis of in-situDRIFTS, the outstanding catalytic activity of LSCF perovskite is mainly induced by the improvement of the redox ability, the enriched generation of oxygen vacancies, and the activation of the lattice oxygen species. The catalytic mechanism of toluene conversion over the LSCF perovskite was revealed to be consistent with Mars-van Krevelen (MVK) models. The knowledge obtained in this study provides helpful guidance for designing efficient heterogeneous catalysts of La-Sr-Co-Fe-O perovskite-type oxides toward efficient catalytic combustion for VOCs elimination.

Probucol (PB), an antioxidant drug, is commonly used as a lipid concentration lowering drug to reduce blood plasma cholesterol levels in the clinic. However, the therapeutic effects of this drug are negatively impacted by its poor water solubility and low oral absorption efficiency. In this study, a PEGylated G5 PAMAM dendrimer (G5-PEG) modified nanoliposome was employed to increase water solubility, transepithelial transport, and oral absorption of PB. The uptake mechanism was explored in vitroin Caco-2 cells with the results suggesting that the absorption improvement of G5-PEG modified PB-liposome (PB-liposome/G5-PEG) was related to P-glycoprotein (P-gp) efflux pump but was independent of caveolae endocytosis pathways. Additionally, plasma lipid concentration lowering effects of PB-liposome/G5-PEG were evaluated in vivoin a LDLR–/– hyperlipidemia mouse model. Compared with saline treated group, treatment with PB-liposome/G5-PEG significantly inhibited the increase of plasma total cholesterol (TC) and triglyceride (TG) of mice induced by a high fat diet. Moreover, its lipid concentration lowering effects and plasma drug concentration were greater than PB alone or commercial PB tablets. Our results demonstrated that PB-liposome/G5-PEG significantly increased the oral absorption of PB and therefore significantly improved its pharmacodynamic effects.

•What is the primary question addressed by this study?We explored the association between long-term trajectories of late-life loneliness and incident dementia.•What is the main finding of this study?Five distinct loneliness trajectories were found: long-term low, persistently decreasing, persistently increasing, long-term moderate, and long-term high. Compared with long-term low loneliness, persistently increasing, long-term moderate, and long-term high loneliness significantly increases the risk of dementia in older adults.•What is the meaning of the finding?To prevent dementia, we should pay attention to the elderly with long-term loneliness and persistently increasing loneliness, especially the elderly with long-term high loneliness.

When exposed to air, gallium-based alloys rapidly form a thin oxide layer with viscoelasticity and high adhesion. Although previous work demonstrated that an oxide layer inhibits liquid metal droplet rebound, there is still a lack of a quantitative study to elaborate how an oxide layer affects the impact dynamics. To address this issue, we experimentally investigate Galinstan droplet impingement on a superhydrophobic CuO nanoblade surface and physically explain the difference in the dynamic characteristics of oxidized and unoxidized droplets. Experimental results show that the effect of an oxide layer becomes prominent during the retraction phase. The high adhesion significantly suppresses retraction and rebound, while the elastic response prevents a droplet from sufficiently stretching and maintains the stability of the morphology. More importantly, we systematically and quantitatively explore the influence of an oxide layer on several critical impact parameters, which contributes to a comprehensive understanding of the impact dynamics of liquid metal droplets. It is indicated that an oxide layer has little effect on the maximum spreading factor and spreading time, whereas it causes a 45% reduction of the restitution coefficient and a 36% increase in contact time. Notably, the scaling laws that describe the critical impact parameters of unoxidized droplets show good agreement with the ones known from ordinary Newtonian fluids.

In this work, we study manpower allocation with time windows and job‐teaming constraints. A set of jobs at dispersed locations requires teams of different types of workers where each job must be carried out in a preestablished time window and requires a specific length of time for completion. A job is satisfied if the required composite team can be brought together at the job's location for the required duration within the job's time window. The objective is to minimize a weighted sum of the total number of workers and the total traveling time. We show that construction heuristics used with simulated annealing is a good approach to solving this NP‐hard problem. In experiments, this approach is compared with solutions found using CPLEX and with lower bounds obtained from a network flow model. © 2005 Wiley Periodicals, Inc. Naval Research Logistics, 2005.