SR

SR
  • 文章类型: Journal Article
    基于CRISPR-Cas的基因组编辑对于推进植物基因组学和作物增强具有巨大的前景。然而,低编辑活动的挑战使编辑事件的识别变得复杂。在这项研究中,我们引入多个单转录单位代理报告(STU-SR)系统来增强基因组编辑植物的选择。这些系统利用为内源基因设计的相同sgRNA来编辑报告基因,在报告基因编辑活性和内源基因之间建立直接联系。采用各种策略来恢复功能性报告基因后基因组编辑,包括在STU-SR-SSA系统中用于同源重组的有效单链退火(SSA)。STU-SR-BE系统利用碱基编辑来恢复起始密码子,丰富的C到T和A到G基础编辑事件。我们的结果展示了这些STU-SR系统在增强单子叶水稻基因组编辑事件中的有效性,包括基于Cas9核酸酶的靶向诱变,胞嘧啶碱基编辑,和腺嘌呤碱基编辑。该系统表现出与Cas9变体的兼容性,比如无PAM的SpRY,并被证明可以促进甘蓝的基因组编辑,双子叶植物作物。总之,我们已经开发了高效和通用的STU-SR系统来富集基因组编辑的植物。
    CRISPR-Cas-based genome editing holds immense promise for advancing plant genomics and crop enhancement. However, the challenge of low editing activity complicates the identification of editing events. In this study, we introduce multiple single transcript unit surrogate reporter (STU-SR) systems to enhance the selection of genome-edited plants. These systems use the same single guide RNAs designed for endogenous genes to edit reporter genes, establishing a direct link between reporter gene editing activity and that of endogenous genes. Various strategies are used to restore functional reporter genes after genome editing, including efficient single-strand annealing (SSA) for homologous recombination in STU-SR-SSA systems. STU-SR-base editor systems leverage base editing to reinstate the start codon, enriching C-to-T and A-to-G base editing events. Our results showcase the effectiveness of these STU-SR systems in enhancing genome editing events in the monocot rice, encompassing Cas9 nuclease-based targeted mutagenesis, cytosine base editing, and adenine base editing. The systems exhibit compatibility with Cas9 variants, such as the PAM-less SpRY, and are shown to boost genome editing in Brassica oleracea, a dicot vegetable crop. In summary, we have developed highly efficient and versatile STU-SR systems for enrichment of genome-edited plants.
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  • 文章类型: Journal Article
    这项研究的主要目的是研究和开发一种在发生核泄漏事件时固定Sr的快速有效方法。煤矸石,煤炭行业未充分利用的固体废物,由于其高含量的二氧化硅-氧化铝氧化物,可用作固化Sr的原料。在本研究中,以煤矸石为原料,采用水热法合成的松质岩中成功地固化了Sr。在大于6M的相对碱浓度下形成稳定的对象石相。当Sr/Al(Si)比<1/6时,对象石是唯一的稳定相随水热温度和时间而变化。当Sr/Al(Si)比增加到1/2时,cancrinite相完全消失,出现了新的锶长石相(SrAl2Si2O8)。PCT浸出实验表明,当Sr/Al(Si)<1/6时,通过在180°C下进行24h的水热合成获得的Sr-cancirnite样品的Sr浸出率很低。
    The primary objective of this study is to investigate and develop a rapid and effective method for the immobilization of Sr in the event of a nuclear leakage incident. Coal gangue, an underutilized form of solid waste from the coal industry, can be used as a raw material for curing Sr due to its high content of silica-alumina oxides. In the present study, Sr was successfully solidified in cancrinite synthesized using a hydrothermal method with coal gangue as raw material. A stable cancrinite phase was formed at a relative alkali concentration of more than 6 M. When the Sr/Al(Si) ratio was <1/6, cancrinite was the only stable phase that varied with the hydrothermal temperature and time. When the Sr/Al(Si) ratio increased to 1/2, the cancrinite phase completely disappeared, and a new strontium feldspar phase (SrAl2Si2O8) appeared. PCT leaching experiments showed that when Sr/Al(Si) < 1/6, the Sr leaching rate of Sr-cancrinite samples obtained by hydrothermal synthesis at 180 °C for 24 h was very low.
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  • 文章类型: Journal Article
    骨疾病的发生率在世界范围内稳步增加。骨组织工程(BTE)已成为骨缺损常规治疗的有希望的替代方法,能够促进骨再生的发育骨支架。在这项研究中,基于离子取代磷酸钙的仿生支架,来源于墨鱼的骨头,使用水热法制备。为了合成Mn2+取代的支架,使用了三种不同的锰浓度(对应于1、2.5和5mol%的Mn将Ca置换成羟基磷灰石)。此外,同时添加等摩尔量(1摩尔%)的两种(Mg2和Sr2)或三种离子(Mn2,Mg2+,和Sr2+)进行。一种化学物质,结构,并使用X射线衍射进行形态表征,傅里叶变换红外光谱,和扫描电子显微镜。离子取代对晶格参数的影响,微晶尺寸,并讨论了检测相的分数。多取代(Mn2+,Mg2+,和Sr2)支架使用简单的真空浸渍用聚己内酯(PCL)涂覆。人骨髓间充质干细胞(hMSCs)的分化,在PCL涂层支架上培养,用组织学评估,免疫组织化学,和逆转录定量聚合酶链反应分析。胶原蛋白I的表达,碱性磷酸酶,并检测牙本质基质蛋白1。讨论了PCL涂层对hMSCs行为的影响。
    The occurrence of bone disorders is steadily increasing worldwide. Bone tissue engineering (BTE) has emerged as a promising alternative to conventional treatments of bone defects, developing bone scaffolds capable of promoting bone regeneration. In this research, biomimetic scaffolds based on ion-substituted calcium phosphates, derived from cuttlefish bone, were prepared using a hydrothermal method. To synthesize Mn2+-substituted scaffolds, three different manganese concentrations (corresponding to 1, 2.5, and 5 mol% Mn substitutions for Ca into hydroxyapatite) were used. Also, syntheses with the simultaneous addition of an equimolar amount (1 mol%) of two (Mg2+ and Sr2+) or three ions (Mn2+, Mg2+, and Sr2+) were performed. A chemical, structural, and morphological characterization was carried out using X-ray diffraction, Fourier transform infrared spectroscopy, and scanning electron microscopy. The effects of the ion substitutions on the lattice parameters, crystallite sizes, and fractions of the detected phases were discussed. Multi-substituted (Mn2+, Mg2+, and Sr2+) scaffolds were coated with polycaprolactone (PCL) using simple vacuum impregnation. The differentiation of human mesenchymal stem cells (hMSCs), cultured on the PCL-coated scaffold, was evaluated using histology, immunohistochemistry, and reverse transcription-quantitative polymerase chain reaction analyses. The expression of collagen I, alkaline phosphatase, and dentin matrix protein 1 was detected. The influence of PCL coating on hMSCs behavior is discussed.
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  • 文章类型: Journal Article
    锶是放射性废物中常见的放射性核素,释放到环境中会对生态环境造成巨大破坏。在这项研究中,选择天然矿物合金烷作为基材,通过冷压/烧结制备固化陶瓷产品,以解决放射性锶的最终处置问题。成功制备了各种晶体结构的陶瓷固化产品,样品的微观形貌和能量色散光谱图像显示Sr在固化产物中均匀分布。Sr2Al2SiO7和SrAl2Si2O8可以稳定固化锶,在固化的产品中形成,并利用密度泛函理论从量子化学计算的角度分析了上述物质的结构特征和稳定性。计算结果表明,Sr2Al2SiO7的整体变形抗力高于SrAl2Si2O8。考虑到CaO杂质的同构取代效应,我们推断固化产物中可能存在Ca2-xSrxAl2SiO7的混合晶体结构。
    Strontium is a common radionuclide in radioactive waste, and its release into the environment can cause enormous damage to the ecosystem environment. In this study, the natural mineral allophane was selected as the substrate to prepare solidified ceramic products by cold pressing/sintering to solve the problem of the final disposal of radioactive strontium. Ceramic solidified products with various crystal structures were successfully prepared, and the microscopic morphology and energy-dispersive spectroscopy images of the samples showed a uniform distribution of Sr in the solidified products. Sr2Al2SiO7 and SrAl2Si2O8, which can stably solidify strontium, were formed in the solidified products, and the structural characteristics and stability of the above-mentioned substances were analyzed from the perspective of quantum chemical calculations using density functional theory. The calculation results showed that the overall deformation resistance of Sr2Al2SiO7 was higher than that of SrAl2Si2O8. Considering the isomorphic substitution effect of CaO impurities, we inferred that a mixed-crystalline structure of Ca2-xSrxAl2SiO7 may be present in the solidified products.
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  • 文章类型: Journal Article
    对铸态Al-4.6Mg合金进行了变形和敏化-脱敏热处理,然后通过光学显微镜研究了Sr的微观结构和增强机理,扫描电子显微镜-能量色散光谱,电子背散射衍射,和透射电子显微镜。Al-4.6Mg合金的析出相主要为β-Al3Mg2、Al6Mn、和Al6(MnCr),纳米级析出相为Al3Mn和Al11Mn4。加入0.1wt。阻碍了β-Al3Mg2的形成。%Sr.此外,沉淀相Al4Sr和纳米级沉淀相τ-Al38Mg58Sr4均匀分布在球形基体中。Sr的加入促进了Mg原子在Al-4.6Mg合金中的再溶解,将Mg在α-Al基体中的溶解度从4.7wt.%至5.1wt。%.显微组织分析表明,Sr元素的添加抑制了合金的回复和再结晶,因为Sr元素提高了再结晶温度。因此,晶粒变形加剧,晶粒尺寸从6.96μm减小到5.39μm,低角度晶界从78.7at%增加到84.6at%,高角度晶界从21.3at%增加到15.4at%。此外,合金的力学性能显著提高,添加Sr元素后,塑性退化。合金的屈服强度主要通过细晶强化来提高,弥散强化,固溶强化,和加工硬化。详细分析了加固机理。
    The as-cast Al-4.6Mg alloy was subjected to deformation and sensitization-desensitization heat treatment, and then the microstructure and the enhancement mechanism of Sr were investigated by optical microscopy, scanning electron microscopy-energy-dispersive spectroscopy, electron backscatter diffraction, and transmission electron microscopy. The precipitation phases of Al-4.6Mg alloy were mainly β-Al3Mg2, Al6Mn, and Al6(Mn Cr), and the nanoscale precipitation phases were Al3Mn and Al11Mn4. The formation of β-Al3Mg2 was hindered by the addition of 0.1 wt.% Sr. In addition, the precipitate phase Al4Sr and the nano-sized precipitate phase τ-Al38Mg58Sr4 were uniformly distributed in the spherical matrix. The addition of Sr promoted the redissolution of Mg atoms in Al-4.6Mg alloy, increasing the solubility of Mg in the α-Al matrix from 4.7 wt.% to 5.1 wt.%. The microstructure analysis showed that Sr addition inhibited the recovery and recrystallization of the alloy because the Sr element elevated the recrystallization temperature. As a result, the grain deformation was intensified, the grain size was decreased from 6.96 μm to 5.39 μm, the low-angle grain boundaries were increased from 78.7 at % to 84.6 at %, and the high-angle grain boundaries were increased from 21.3 at % to 15.4 at %. Furthermore, the mechanical properties of the alloy were significantly improved, and the plasticity degraded after the addition of the Sr element. The yield strength of the alloy was enhanced mainly through fine grain strengthening, dispersion strengthening, solid solution strengthening, and working hardening. The strengthening mechanisms were analyzed in detail.
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  • 文章类型: Journal Article
    沉淀的磷酸锡(IV)的样品,使用水热改性,微波炉,和机械化学程序,在Cs(I)的过程中进行了研究,高级(二)、和U(VI)离子吸附。使用XRD对初始和改性样品在吸附前后进行了研究,XRF,FTIR,和氮气吸附-解吸。发现改性程序将初始样品的微孔结构转化为中孔-大孔结构。因此,相对于所有离子的吸附能力增加了数倍。这表明了多孔结构的决定性作用,主要内容,中孔尺寸对磷酸锡吸附活性的影响。样品,以湿凝胶的形式处理,这是一个新颖的程序,显示了最大吸附指标。所有测试离子的吸附由Langmuir等温线描述。
    The samples of precipitated tin (IV) phosphate, modified using hydrothermal, microwave, and mechanochemical procedures, were studied in the process of Cs(I), Sr(II), and U(VI) ion sorption. The initial and modified samples were investigated before and after sorption using XRD, XRF, FTIR, and nitrogen adsorption-desorption. It was found that the modification procedures transformed the micro-mesoporous structure of the initial sample into a meso-macroporous structure. As a result, the sorption capacity in relation to all ions increases several times. This indicates the determining role of the porous structure, primary content, and mesopore size on the sorption activity of tin phosphate. The samples, treated in the form of a wet gel, which is a novel procedure, showed the maximum sorption indicators. The sorption of all the tested ions is described by the Langmuir isotherm.
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  • 文章类型: Journal Article
    心脏钙交替被定义为Ca瞬时(CaT)振幅的逐搏交替,并且与心律失常有关。包括心房颤动.我们使用高分辨率线扫描共聚焦Ca成像研究了离体兔心房肌细胞中心房交替的机制。通过增加起搏频率来诱导交替,直到观察到稳定的交替(室温下1.6-2.5Hz)。在心房肌细胞中,动作电位诱导的Ca释放在细胞外围开始,随后通过Ca诱导的Ca释放(CICR)以Ca波状方式向细胞中心传播。由新确定的“火-扩散-吸收-火”(FDUF)机制驱动。CaT交替的发展伴随着CaT时空组织的特征性变化。在CaT的后期,中央[Ca]i超过外周[Ca]i,这表明从向心到离心的亚细胞[Ca]i梯度逆转。这种梯度逆转导致CICR传播的逆转,在大振幅交替CaT期间引起二次Ca释放,从而延长了CaT,增强Ca释放难治性并减少后续搏动中的Ca释放,从而提高了CaT交替的程度。这里,我们提出了“反向FDUF”机制作为心房CaT交替的一种新的细胞机制,这解释了中枢与外周Ca释放的解偶联如何导致传播性CICR和交替体的逆转。
    Cardiac calcium alternans is defined as beat-to-beat alternations of Ca transient (CaT) amplitude and has been linked to cardiac arrhythmia, including atrial fibrillation. We investigated the mechanism of atrial alternans in isolated rabbit atrial myocytes using high-resolution line scan confocal Ca imaging. Alternans was induced by increasing the pacing frequency until stable alternans was observed (1.6-2.5 Hz at room temperature). In atrial myocytes, action potential-induced Ca release is initiated in the cell periphery and subsequently propagates towards the cell center by Ca-induced Ca release (CICR) in a Ca wave-like fashion, driven by the newly identified \'fire-diffuse-uptake-fire\' (FDUF) mechanism. The development of CaT alternans was accompanied by characteristic changes of the spatio-temporal organization of the CaT. During the later phase of the CaT, central [Ca]i exceeded peripheral [Ca]i that was indicative of a reversal of the subcellular [Ca]i gradient from centripetal to centrifugal. This gradient reversal resulted in a reversal of CICR propagation, causing a secondary Ca release during the large-amplitude alternans CaT, thereby prolonging the CaT, enhancing Ca-release refractoriness and reducing Ca release on the subsequent beat, thus enhancing the degree of CaT alternans. Here, we propose the \'reverse FDUF\' mechanism as a novel cellular mechanism of atrial CaT alternans, which explains how the uncoupling of central from peripheral Ca release leads to the reversal of propagating CICR and to alternans.
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  • 文章类型: Journal Article
    Ionic substitutions within the hydroxyapatite lattice are a widely used approach to mimic the chemical composition of the bone mineral. In this work, Sr-substituted and Mg- and Sr-co-substituted calcium phosphate (CaP) scaffolds, with various levels of strontium and magnesium substitution, were prepared using the hydrothermal method at 200 °C. Calcium carbonate skeletons of cuttlefish bone, ammonium dihydrogenphosphate (NH4H2PO4), strontium nitrate (Sr(NO3)2), and magnesium perchlorate (Mg(ClO4)2) were used as reagents. Materials were characterized by means of X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM). Whole powder pattern decomposition refinements of XRD data indicated that increased magnesium content in the Mg- and Sr-co-substituted scaffolds was related to an increased proportion of the whitlockite (WH) phase in the biphasic hydroxyapatite (HAp)/WH scaffolds. In addition, refinements indicate that Sr2+ ions have replaced Ca2+ sites in the WH phase. Furthermore, PCL-coated Mg-substituted and Sr- and Mg-co-substituted scaffolds, with the HAp:WH wt. ratio of 90:10 were prepared by vacuum impregnation. Results of compression tests showed a positive impact of the WH phase and PCL coating on the mechanical properties of scaffolds. Human mesenchymal stem cells (hMSCs) were cultured on composite scaffolds in an osteogenic medium for 21 days. Immunohistochemical staining showed that Mg-Sr-CaP/PCL scaffold exhibited higher expression of collagen type I than the Mg-CaP/PCL scaffold, indicating the positive effect of Sr2+ ions on the differentiation of hMSCs, in concordance with histology results. Reverse transcription-quantitative polymerase chain reaction (RT-qPCR) analysis confirmed an early stage of osteogenic differentiation.
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  • 文章类型: Journal Article
    The selective laser melting (SLM) forming process of 24CrNiMo alloy steel was optimized by orthogonal experiment. The density and microstructure of the sample were analyzed, and the optimized process parameters were as follows: laser power 300 W, scanning speed 530 mm/s. The 24CrNiMo alloy steel samples were prepared with optimized parameters. The relationship between residual stress and thermal fatigue and the effect of stress-relieving annealing (SR) on residual stress were analyzed. The density of the sample was found to increase at first and then to decrease with the increase of laser power and then to decrease with the increase of scanning speed. Increasing the laser power and scanning speed widened and deepened the weld. Under the optimized process window, the formability of 24CrNiMo alloy steel samples was improved significantly. The residual stress distribution was tensile stress, which had a negative effect on the thermal fatigue properties of the sample. After SR, the residual stress changed to compressive stress, which had a positive effect on the thermal fatigue properties of the samples. Compared with the deposited state, the thermal fatigue cracks were significantly shortened after SR, which was able to further promote the improvement of thermal fatigue performance. The gradient residual stress test showed that the gradient residual stress in the edge region and the central region of the deposited sample had the same trend, and decreased gradually from the surface layer to the base layer.
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  • 文章类型: Journal Article
    背景:对于运动员来说,由于在重大比赛中的压力,他们的表现出现了故障,这一直是一个问题。注意模式的改变和负性情感(NA)引起的应激反应(SR)的出现是对运动员成绩影响较大的直接原因。探讨如何改善运动员在紧张环境下的注意力偏差(AB)和SR是一个热门话题。
    目的:本研究旨在分析视觉搜索任务(VST)训练对压力情况下运动员AB和SR的改善效果。
    方法:将沈阳体育学院62名国家2级以上男子篮球运动员分为实验组(EG)和对照组(CG)。在EG中使用了视觉搜索任务训练程序(快乐,悲伤,恶心,中性面孔)和假训练计划用于CG(所有具有中性表情的面孔)两个月。在压力的情况下,对所有受试者训练前后的注意力行为进行了测试。采用生理一致性和自主平衡系统同步记录心率变异性。并行频域分析被划分为极低频带(VLF),低频(LF),高频(HF)和总频谱(TP)。归一化处理获得的指标如HFnorm,LFnorm,LF/HF。采取e-prime2.0软件获得注意力偏向得分。训练前后采用积极和消极情感量表(PANAS)和压力自评量表进行评估。
    结果:两组自评压力均低于训练前,试验组压力低于对照组(P<0.05)。培训后,实验组的积极情绪高于对照组,EG低于CG(P<0.05)。培训后,EG中快乐和中性面孔的注意力偏向得分高于CG,悲伤和厌恶面孔的注意偏向得分低于CG(P<0.05)。培训后,EG的LF/HF和LFnorm低于CG,HFnorm高于CG(P<0.05)。
    结论:视觉搜索任务训练能有效提高运动员PA和AB的阳性信息,减少负面信息和心理压力的关注偏差,解除SR。
    BACKGROUND: it has always been a problem for athletes that their performance is out of order due to pressure in major competitions. The change of attention pattern and the emergence of stress response (SR) caused by negative affect (NA) are the direct reasons for the greater impact on the performance of athletes. It is a hot topic to explore how to improve attention bias (AB) and SR of athletes in stressful situations.
    OBJECTIVE: the study aimed to analyze the improvement effect of visual search task (VST) training on AB and SR of athletes under pressure situations.
    METHODS: 62 male basketball players with national level 2 or above of Shenyang sports institute were divided into experimental group (EG) and control group (CG). Visual search task training program was used in the EG (happy, sad, disgusted, neutral faces) and sham training program was used in the CG (all faces with neutral expression) for two months. Under the stress situation, attention behavior of all subjects before and after training was tested. Physiological coherence and autonomic balance system were used to record heart rate variability synchronously. Parallel frequency domain analysis was divided into very low frequency band (VLF), low frequency (LF), high frequency (HF) and total spectrum (TP). The normalized treatment obtained indexes such as HFnorm, LFnorm, and LF/HF. The e-prime 2.0 software was adopted to obtain the attention bias score. The Positive and Negative Affect Scale (PANAS) and the self-rating stress scale were adopted for evaluation before and after training.
    RESULTS: the self-rating pressure in the two groups was lower than that before the training, and the pressure in the experimental group was lower than that in the control group (P < 0.05). After training, the positive emotion of the experimental group was higher than that of the control group, and the EG was lower than that of the CG (P < 0.05). After training, the score of attention bias of happy and neutral faces in the EG was higher than that of theCG, while the score of attention bias of sad and disgusted faces was lower than that of the CG (P < 0.05). After training, LF/HF and LFnorm in the EG were lower than those in the CG, and HFnorm was higher than those in the CG (P < 0.05).
    CONCLUSIONS: the training of visual search task can effectively improve the athletes\' PA and AB of positive information, reduce the attention bias of negative information and psychological pressure, and relieve theSR.
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