Noncytotoxic Dy3+-activated glass emits cool white light for near ultraviolet-based white light-emitting diodes,visible lasers,and biomedical applications

Using the melt quenching technique, a lithium zinc borate glass (LZB) system with trivalent dysprosium ions (Dy³⁺) was synthesized, and the luminescence and lasing properties of these materials were examined for the generation of white light. Structural investigation through X-ray diffraction revealed that the prepared glass had an amorphous nature. The optimized glass containing 0.5 Dy³⁺ had a direct optical band gap of 2.782 eV and an indirect optical band gap of 3.110 eV. A strong excitation band at 386 nm (⁶H_15/2→⁴I_13/2) was recognized in the ultraviolet (UV) light region of its excitation spectrum. Emission bands could be seen in the photoluminescence spectrum at 659, 573, and 480 nm under the 386 nm excitation. These transitions of emission resembled electronic transitions such as (⁴F_9/2→⁶H_11/2), (⁴F_9/2→⁶H_13/2), and (⁴F_9/2→⁶H_15/2). In a pristine glass matrix, the higher intensity ratio of yellow to blue can result in the production of white light. The optimized Dy³⁺ ion concentration was observed to be 0.5 mol%. In addition, an analysis of lifetime decay was conducted for all synthesized glasses, and their decay trends were systematically investigated. Noticeably, we assessed the photometric parameters and found that they were close to the white light standard. Furthermore, a cytotoxicity study was carried out using lung fibroblast (WI-38) cell lines for the optimized 0.5Dy³⁺-doped LZB glass and it appeared to be noncytotoxic. It is clear from the results that the noncytotoxic LZB glass doped with 0.5 Dy³⁺ ions could be a suggestive choice for the manufacture of white light-emitting diodes and lasers using near-UVs.     

Age-mediated gut microbiota dysbiosis promotes the loss of dendritic cells tolerance

The old age-related loss of immune tolerance inflicts a person with a wide range of autoimmune and inflammatory diseases. Dendritic cells (DCs) are the sentinels of the immune system that maintain immune tolerance through cytokines and regulatory T-cells generation. Aging disturbs the microbial composition of the gut, causing immune system dysregulation. However, the vis-à-vis role of gut dysbiosis on DCs tolerance remains highly elusive. Consequently, we studied the influence of aging on gut dysbiosis and its impact on the loss of DC tolerance. We show that DCs generated from either the aged (DC^Old) or gut-dysbiotic young (DC^Dysbiotic) but not young (DC^Young) mice exhibited loss of tolerance, as evidenced by their failure to optimally induce the generation of Tregs and control the overactivation of CD4⁺ T cells. The mechanism deciphered for the loss of DC^Old and DC^Dysbiotic tolerance was chiefly through the overactivation of NF-κB, impaired frequency of Tregs, upregulation in the level of pro-inflammatory molecules (IL-6, IL-1β, TNF-α, IL-12, IFN-γ), and decline in the anti-inflammatory moieties (IL-10, TGF-β, IL-4, IDO, arginase, NO, IRF-4, IRF-8, PDL1, BTLA4, ALDH2). Importantly, a significant decline in the frequency of the Lactobacillus genus was noticed in the gut. Replenishing the gut of old mice with the Lactobacillus plantarum reinvigorated the tolerogenic function of DCs through the rewiring of inflammatory and metabolic pathways. Thus, for the first time, we demonstrate the impact of age-related gut dysbiosis on the loss of DC tolerance. This finding may open avenues for therapeutic intervention for treating age-associated disorders with the Lactobacillus plantarum.     

Alginate/chitosan hydrogels as perspective transport systems for cefotaxime

This work reports synthesis of pH-responsive alginate/chitosan hydrogel spheres with the average diameter of 2.0 ± 0.05 mm, which contain cefotaxime that is an antibiotic of the cefalosporine group. The spheres provided the cefotaxime encapsulation efficiency of 95 ± 1%. An in vitro release of cefotaxime from the spheres in the media that simulate human biological fluids in peroral delivery conditions was found to be a pH-dependent process. The analysis of cefotaxime release kinetics by the Korsmeyer–Peppas model revealed a non-Fickian mechanism of its diffusion, which may be related to intermolecular interactions occurring between the antibiotic and chitosan. Conductometry, UV spectroscopy, and IR spectroscopy were used to study complexation of chitosan with cefotaxime in aqueous media with varied pH, characterize the composition of the complexes, and calculate their stability constants. The composition of the cefotaxime–chitosan complexes was found to correspond to the 1.0:4.0 and 1.0:2.0 molar ratios of the components at pH 2.0 and 5.6, respectively. Quantum chemical modeling was used to evaluate energy characteristics of chitosan–cefotaxime complexation considering the influence of a solvent.     

Subcellular Distribution and Chemical Forms of Cadmium in the Medicine Food Homology Plant <i>Platycodon grandiflorum</i> (Jacq.) A.DC.

Although Platycodon grandiflorum (Jacq.) A.DC. is a renowned medicine food homology plant, reports of excessive cadmium (Cd) levels are common, which affects its safety for clinical use and food consumption. To enable its Cd levels to be regulated or reduced, it is necessary to first elucidate the mechanism of Cd uptake and accumulation in the plant, in addition to its detoxification mechanisms. This present study used inductively couple plasma-mass-spectrometry to analyze the subcellular distribution and chemical forms of Cd in different tissues of P. grandiflorum. The experimental results showed that Cd was mainly accumulated in the roots [predominantly in the cell wall (50.96%–61.42%)], and it was found primarily in hypomobile and hypotoxic forms. The proportion of Cd in the soluble fraction increased after Cd exposure, and the proportion of insoluble phosphate Cd and oxalate Cd increased in roots and leaves, with a higher increase in oxalate Cd. Therefore, it is likely that root retention mechanisms, cell wall deposition, vacuole sequestration, and the formation of low mobility and low toxicity forms are tolerance strategies for Cd detoxification used by P. grandiflorum. The results of this study provide a theoretical grounding for the study of Cd accumulation and detoxification mechanisms in P. grandiflorum, and they can be used as a reference for developing Cd limits and standards for other medicine food homology plants.     

Thermal stress exposure of pupal oriental fruit fly has strong and trait-specific consequences in adult flies

Global climate change is projected to increase the incidence of heat waves, their magnitude and duration resulting in insects experiencing increasing environmental stress in both natural and managed ecosystems. While studies on insect thermal tolerance are rapidly increasing, variation across developmental or juvenile stress cross-stage effects within and across generations remain largely unexplored. Yet in holometabolous insects, heat stress at an early developmental stage may influence performance and survival during later stages. Here, we investigated the effects of pupal mild heat stress on the performance of laboratory-reared adult Bactrocera dorsalis (Hendel) (Diptera: Tephritidae) measured as longevity, critical thermal maximum (CT_max), critical thermal minima (CT_min), heat knockdown time (HKDT) and chill coma recovery time (CCRT). Pupal heat stress significantly influenced performance of B. dorsalis adults resulting in impaired longevity and heat tolerance (CT_max and HKDT) in both sexes with improved and compromised cold tolerance (CT_min and CCRT) in females and males, respectively. These findings highlight the role of juvenile stages in mediating stress responses at adult stages. For B. dorsalis, pupal heat stress largely compromised thermal tolerance implying that the species has limited potential to shift its geographic range in heat prone areas. Significant benefits in cold tolerance in females following heat stress may help in improving survival in the cold in the short-term despite restricted activity to the same traits in males. This study suggests that basal heat tolerance and not short-term compensatory thermal plasticity following heat stress may have aided the recent invasion of B. dorsalis in African landscapes.     

中国转基因大豆的产业化策略

大豆是事关人民生活和经济社会发展的重要农产品之一,提高大豆生产水平和增加自给能力,是中国农业生产必须解决的重大问题。由于中国耕地资源不足的限制,科技创新是提升大豆生产能力的唯一出路。转基因育种是推动大豆生产发展的颠覆性技术,对美国、巴西和阿根廷等世界主产国大豆产业的发展发挥了重要作用。经过20多年的科技创新,中国转基因耐除草剂和抗虫育种技术已经成熟,这些产品的产业化种植可显著降低大豆生产成本和提升单产水平。基于中国转基因大豆技术发展进度和大豆生产的国情特点,我们提出了采用如下策略科学有序推进产业化工作。一是,在产品应用时间上,按照单一耐草甘膦除草剂、多个基因耐草甘膦和草铵膦等多种除草剂,以及耐除草剂与抗虫等复合性状等产品,依次推进相关种子的产业化;二是,在产品区域布局上,按照靶标杂草和害虫的地理分布特点顶层设计各种耐除草剂和抗虫大豆产品的种植区域;三是,在生物安全管理上,研发应用抗性杂草和害虫种群监测与治理技术,延长转基因产品的使用寿命。同时,还要加强野生大豆资源的保护工作,降低转基因大豆基因漂移对野生大豆生物多样性的影响。     

拟南芥ACOL8基因在乙烯合成与响应中的功能分析

植物激素乙烯在多种生理生化过程中发挥重要作用,但其在特定组织器官中的合成机制尚不完全清楚。拟南芥中存在12个功能未知的ACC氧化酶类似蛋白（ACO-like homolog,ACOL）,运用基因定点编辑技术构建了ACOL8的功能丧失型突变体,发现该基因的突变削弱了经典的乙烯“三重反应”。与野生型相比,突变体黄化幼苗下胚轴及主根的长度显著增加,这与突变体对外源ACC的敏感性下降现象一致。同时还发现ACOL8基因的表达受乙烯信号的正反馈调控,EIN3过表达增强其表达水平,而etr1-3的突变则产生相反效应。再者,在正常条件下,ACOL8基因的突变并未影响拟南芥的生长;但在盐胁迫条件下,突变体的根冠比显著下降,这说明该基因参与植物的盐胁迫响应。综上,这些结果说明ACOL8可能具有ACC氧化酶的功能,参与乙烯的合成与响应。     

免疫反应动力学的几个数学模型

免疫系统对抗原刺激的应答过程非常复杂,由抗原刺激导致抗体产生的现象,可借助数学模型的研究获得有意义的结果。本文讨论有关抗体产生与免疫反应的动力学的问题,介绍有关的数学模型,并根据近斯免疫学研究的进展分析了若干模型。