Selective

选择性
  • 文章类型: Journal Article
    C-C单键的选择性硼氢化在化学工业中提出了基本挑战。以前,仅使用贵金属Ir和Rh的催化系统,与N-和P-配体结合,可以做到这一点,确保键裂解和选择性。与此形成鲜明对比的是,我们发现了一种用于C-C单键硼氢化的前所未有的通用无过渡金属系统。该方法不含过渡金属和配体,并且在化学和区域选择性方面超越了过渡金属系统,基材多功能性,或收益率。此外,我们的系统容忍各种官能团,如Ar-X(X=卤化物),杂环,酮,酯类,酰胺,硝基,腈,和C=C双键,它们通常在过渡金属的存在下容易发生硼氢化。因此,具有不同结构和功能的不同范围的γ-硼酸化胺已经容易地获得。实验机理研究,密度泛函理论(DFT),和内在键轨道(IBO)计算揭示了氢硼烷促进的C-C键裂解和氢化物转移反应途径。酰胺的羰基抑制游离N-H和氢硼烷之间的脱氢。酰胺的氮上的孤对电子促进环丙烷中C-C键的裂解。
    Selective hydroboration of C-C single bonds presents a fundamental challenge in the chemical industry. Previously, only catalytic systems utilizing precious metals Ir and Rh, in conjunction with N- and P- ligands, could achieve this, ensuring bond cleavage and selectivity. In sharp contrast, we discovered an unprecedented and general transition-metal-free system for the hydroboration of C-C single bonds. This methodology is transition-metal and ligand-free and surpasses the transition-metal systems regarding chemo- and regioselectivities, substrate versatility, or yields. In addition, our system tolerates various functional groups such as Ar-X (X = halides), heterocyclic rings, ketones, esters, amides, nitro, nitriles, and C=C double bonds, which are typically susceptible to hydroboration in the presence of transition metals. As a result, a diverse range of γ-boronated amines with varied structures and functions has been readily obtained. Experimental mechanistic studies, density functional theory (DFT), and intrinsic bond orbital (IBO) calculations unveiled a hydroborane-promoted C-C bond cleavage and hydride-shift reaction pathway. The carbonyl group of the amide suppresses dehydrogenation between the free N-H and hydroborane. The lone pair on the nitrogen of the amide facilitates the cleavage of C-C bonds in cyclopropanes.
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  • 文章类型: Journal Article
    细胞周期蛋白依赖性激酶7与细胞周期蛋白H和MAT1一起形成CDK激活复合物(CAK),通过细胞周期CDK的T环磷酸化指导细胞周期进程。CDK7的药理学抑制导致细胞和体内模型的选择性抗癌作用,激发了几个正在进行的关于这个目标的临床研究。目前的CDK7抑制剂是其催化活性的可逆或共价抑制剂。我们假设小分子靶向蛋白降解(TPD)可能由于支架功能的丧失而导致不同的药理学。这里,我们报道了一种有效的CDK7降解剂的设计和表征,该降解剂由与CRL2VHL招募剂连接的ATP竞争性CDK7结合剂组成.JWZ-5-13有效降解多种癌细胞中的CDK7并导致细胞增殖的有效抑制。此外,化合物JWZ-5-13在小鼠中进行的药代动力学研究中显示出生物利用度。因此,JWZ-5-13是研讨CDK7降解的药理后果的有用化学探针。
    Cyclin-dependent kinase 7, along with cyclin H and MAT1, forms the CDK-activating complex (CAK), which directs cell cycle progression via T-loop phosphorylation of cell cycle CDKs. Pharmacological inhibition of CDK7 leads to selective anti-cancer effects in cellular and in vivo models, motivating several ongoing clinical investigations of this target. Current CDK7 inhibitors are either reversible or covalent inhibitors of its catalytic activity. We hypothesized that small molecule targeted protein degradation (TPD) might result in differentiated pharmacology due to the loss of scaffolding functions. Here, we report the design and characterization of a potent CDK7 degrader that is comprised of an ATP-competitive CDK7 binder linked to a CRL2VHL recruiter. JWZ-5-13 effectively degrades CDK7 in multiple cancer cells and leads to a potent inhibition of cell proliferation. Additionally, compound JWZ-5-13 displayed bioavailability in a pharmacokinetic study conducted in mice. Therefore, JWZ-5-13 is a useful chemical probe to investigate the pharmacological consequences of CDK7 degradation.
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  • 文章类型: Journal Article
    作为一种有毒的挥发性有机污染物(TVOC),甲醛对微生物有毒性作用,从而抑制了甲醛废水处理的生化过程。因此,甲醛的选择性降解对实现高效、低成本的甲醛废水处理具有重要意义。本研讨构建了非均相Fe-ZSM-5/H2O2Fenton体系以选择性降解目标化合物。通过将Fe3+固定在ZSM-5分子筛的表面,成功制备了Fe-ZSM-5。XRD,BET和FT-IR光谱研究表明Fe-ZSM-5主要由微孔组成。研究了不同变量对甲醛选择性非均相Fenton降解性能的影响。在优化的Fenton系统中360分钟后,与葡萄糖相比,甲醛降解率为93.7%,甲醛选择性为98.2%。值得注意的是,所得到的选择性Fenton氧化体系具有广泛的pH适用性,从3.0到10.0。此外,Fe-ZSM-5在五个连续循环中使用,而甲醛降解效率没有显著下降。活性氧物质清除剂的使用表明羟基自由基是负责降解甲醛的主要活性物质。此外,该系统在高浓度甲醛的情况下获得了巨大的降解性能,降解效率达95.0%以上。
    As a toxic Volatile Organic Pollutant (TVOC), formaldehyde has a toxic effect on microorganisms, consequently inhibiting the biochemical process of formaldehyde wastewater treatment. Therefore, the selective degradation of formaldehyde is of great significance in achieving high-efficiency and low-cost formaldehyde wastewater treatment. This study constructed a heterogeneous Fe-ZSM-5/H2O2 Fenton system f or the selective degradation of target compounds. By immobilizing Fe3+ onto the surface of a ZSM-5 molecular sieve, Fe-ZSM-5 was prepared successfully. XRD, BET and FT-IR spectral studies showed that Fe-ZSM-5 was mainly composed of micropores. The influences of different variables on formaldehyde-selective heterogeneous Fenton degradation performance were studied. The 93.7% formaldehyde degradation and 98.2% selectivity of formaldehyde compared with glucose were demonstrated in the optimized Fenton system after 360 min. Notably, the resultant selective Fenton oxidation system had a wide range of pH suitability, from 3.0 to 10.0. Also, the Fe-ZSM-5 was used in five consecutive cycles without a significant drop in formaldehyde degradation efficiency. The use of reactive oxygen species scavengers indicated that the hydroxyl radical was the primary active species responsible for degrading formaldehyde. Furthermore, great degradation performance was acquired with high concentrations of formaldehyde for this system, and the degradation efficiency was more than 95.0%.
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  • 文章类型: Journal Article
    光热解是将辐射能转化为热能的过程,通过热扩散导致周围组织或细胞的破坏。基于光热解的激光治疗已被广泛用于治疗各种皮肤疾病,例如皮肤癌和葡萄酒色斑。它提供了一些好处,如非侵入性和选择性治疗。然而,光的使用,例如,激光,对于安全和有效的光热解变得具有挑战性,由于光进入皮肤组织的有限渗透以及黑色素的存在,它吸收了这种光。为了解决当前的问题,在这项工作中,我们提出了一种涂有金的光学微针透镜阵列(OMLA),可以直接将光传递到目标皮肤层,而不会被周围组织以及黑色素吸收,从而提高了光热治疗的效率。我们开发了一种新颖的制造方法,框架引导的微成型,通过组装两个同时对齐的阴模来准备OMLA。此外,对OMLA的光学和传热特性进行了评估。我们希望我们开发的OMLA能够通过将光子精确传递到目标区域,在实现更有效的激光治疗方面发挥关键作用。
    Photothermolysis is the process that converts radiation energy into thermal energy, which results in the destruction of surrounding tissues or cells through thermal diffusion. Laser therapy that is based on photothermolysis has been a widely used treatment for various skin diseases such as skin cancers and port-wine stains. It offers several benefits such as non-invasiveness and selective treatment. However, the use of light, e.g., laser, for safe and effective photothermolysis becomes challenging due to the limited penetration of light into skin tissue as well as the presence of melanin, which absorbs this light. To solve the current issues, we propose an optical microneedle-lens array (OMLA) coated with gold in this work to directly deliver light to targeted skin layers without being absorbed by surrounding tissues as well as melanin, which results in the improvement of the efficiency of photothermal therapy. We developed a novel fabrication method, frame-guided micromolding, to prepare the OMLA by assembling two negative molds with simultaneous alignment. In addition, evaluations of the optical and heat transfer characteristics of the OMLA were performed. We expect our developed OMLA to play a crucial role in realizing more effective laser therapy by allowing the precise delivery of photons to the target area.
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  • 文章类型: Journal Article
    半纤维素可以通过酸预处理选择性地去除。在这项研究中,采用硫酸铝预处理辅助的稀硫酸实现了半纤维素的选择性去除。最佳预处理条件为160°C,1.5wt%硫酸铝,0.7wt%稀硫酸,和40分钟。组分分析结果表明,半纤维素和木质素的去除率分别达到98.05%和9.01%,分别,这表明硫酸铝预处理辅助稀硫酸可以高选择性地去除半纤维素。结构特征(SEM,FTIR,BET,TGA,和XRD)表明预处理改变了粗糙度,结晶度孔径,和玉米秸秆的官能团,有利于提高酶解效率。本研究为半纤维素的高选择性分离提供了一种新的途径,从而为其随后的高价值利用提供了新的见解。
    Hemicellulose can be selectively removed by acid pretreatment. In this study, selective removal of hemicellulose was achieved using dilute sulfuric acid assisted by aluminum sulfate pretreatment. The optimal pretreatment conditions were 160 °C, 1.5 wt% aluminum sulfate, 0.7 wt% dilute sulfuric acid, and 40 min. A component analysis showed that the removal rate of hemicellulose and lignin reached 98.05% and 9.01%, respectively, which indicated that hemicellulose was removed with high selectivity by dilute sulfuric acid assisted by aluminum sulfate pretreatment. Structural characterizations (SEM, FTIR, BET, TGA, and XRD) showed that pretreatment changed the roughness, crystallinity, pore size, and functional groups of corn straw, which was beneficial to improve the efficiency of enzymatic hydrolysis. This study provides a new approach for the high-selectivity separation of hemicellulose, thereby offering novel insights for its subsequent high-value utilization.
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  • 文章类型: Journal Article
    硬化蛋白是一种分泌型糖蛋白,主要在骨细胞中表达,通过拮抗Wnt/β-catenin信号通路抑制骨形成,和硬化蛋白的loop3区域最近被发现作为骨合成代谢治疗的一个新的治疗靶点而不增加心血管风险。在这里,我们使用基于结构的虚拟筛选来搜索选择性靶向硬化蛋白loop的小分子抑制剂3.一种新型天然产物命中ZINC4228235(THFA)被鉴定为硬化蛋白环3选择性抑制剂,其针对硬化蛋白环3的Kd值为42.43nM。使用分子建模指导的修饰对THFA进行简化和推导,从而发现了一种有效的环3选择性小分子抑制剂,化合物(4-(3-乙酰氨基丙-1-炔-1-基)苯甲酰基)甘氨酸(AACA),与命中的THFA相比具有改善的结合亲和力(Kd=15.4nM)。进一步的体外实验表明,化合物AACA可以减弱转染的硬化素对Wnt信号和骨形成的抑制作用。这些结果使AACA成为开发抗骨质疏松症药物而不增加心血管风险的潜在候选者。
    Sclerostin is a secreted glycoprotein that expresses predominantly in osteocytes and inhibits bone formation by antagonizing the Wnt/β-catenin signaling pathway, and the loop3 region of sclerostin has recently discovered as a novel therapeutic target for bone anabolic treatment without increasing cardiovascular risk. Herein, we used a structural based virtual screening to search for small molecular inhibitors selectively targeting sclerostin loop3. A novel natural product hit ZINC4228235 (THFA) was identified as the sclerostin loop3-selective inhibitor with a Kd value of 42.43 nM against sclerostin loop3. The simplification and derivation of THFA using molecular modeling-guided modification allowed the discovery of an effective and loop3-selective small molecular inhibitor, compound (4-(3-acetamidoprop-1-yn-1-yl)benzoyl)glycine (AACA), with improved binding affinity (Kd = 15.4 nM) compared to the hit THFA. Further in-vitro experiment revealed that compound AACA could attenuate the suppressive effect of transfected sclerostin on Wnt signaling and bone formation. These results make AACA as a potential candidate for development of anti-osteoporosis agents without increasing cardiovascular risk.
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  • 文章类型: Journal Article
    众所周知,蛋白质具有惊人的功能阵列,这要归功于它们相互协作和调节彼此特性的能力。细胞内部,蛋白质可以组装成大型多亚基复合物来执行复杂的细胞功能。正确组装和维持大分子蛋白质复合物的功能状态对人类健康至关重要。否则会导致功能丧失和有害物质的潜在积累,它与多种人类疾病如神经变性和癌症有关。自噬吞噬自噬体中的胞浆物质,因此最适合消除完整的大分子复合物而不分解它们,这可能会干扰从头组装。在这次审查中,我们讨论了自噬在大分子复合物选择性降解中的作用。我们重点介绍了不同大分子复合物及其选择性自噬降解的最新知识。我们强调了我们对这些大分子复合物降解所需的理解的空白,并指出了未来的工作,这些工作可能会阐明通过自噬调节大分子复合物的选择性降解。
    Proteins are known to perform an astonishing array of functions thanks to their ability to cooperate and modulate each other\'s properties. Inside cells, proteins can assemble into large multi-subunit complexes to carry out complex cellular functions. The correct assembly and maintenance of the functional state of macromolecular protein complexes is crucial for human health. Failure to do so leads to loss of function and potential accumulation of harmful materials, which is associated with a variety of human diseases such as neurodegeneration and cancer. Autophagy engulfs cytosolic material in autophagosomes, and therefore is best suited to eliminate intact macromolecular complexes without disassembling them, which could interfere with de novo assembly. In this review, we discuss the role of autophagy in the selective degradation of macromolecular complexes. We highlight the current state of knowledge for different macromolecular complexes and their selective autophagic degradation. We emphasize the gaps in our understanding of what it takes for these large macromolecular complexes to be degraded and point to future work that may shed light on the regulation of the selective degradation of macromolecular complexes by autophagy.
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  • 文章类型: Journal Article
    背景:这项研究评估了选择性人格针对性的PreVenture计划在青春期和成年早期的7年内减少大麻和兴奋剂使用的功效。
    方法:一项整群随机对照试验在14所澳大利亚学校进行。学校被随机分配到PreVenture,一个简短的针对人格的选择性干预,包括两个90分钟的主持人主导的会议,相隔一周,或对照组(照常进行健康教育)。只有在四种人格特质之一(焦虑敏感性,消极思维,冲动,感觉寻求)被包括在内。学生在2012年至2019年之间完成了在线自我报告问卷:基线;干预后;1-,2-,3-,基线后5.5年和7年。结果是过去6个月的大麻使用,兴奋剂使用(MDMA,甲基苯丙胺或苯丙胺)和与大麻有关的危害。
    结果:样本包括基线时的438名青少年(Mage=13.4岁;SD=0.47)。在这7年中,保留率从51%到79%不等。与对照组相比,PreVenture组每年发生大麻相关危害的几率显著降低(OR=0.78,95%CI=0.65~0.92).然而,在7年期间,大麻使用(OR=0.84,95%CI=0.69-1.02)或兴奋剂使用(OR=1.07,95%CI=0.91-1.25)的增长没有显著组间差异.
    结论:随着时间的推移,PreVenture有效地减缓了大麻相关危害的增长,然而,由于缺乏7年试验的数据,为了更好地了解PreVenture干预措施对澳大利亚年轻人使用大麻和兴奋剂的影响,可能需要进行复制试验.替代实施战略,例如在青春期后期提供干预和/或提供助推器课程,可能是有益的。
    BACKGROUND: This study evaluated the efficacy of the selective personality-targeted PreVenture program in reducing cannabis and stimulant use over a 7-year period spanning adolescence and early adulthood.
    METHODS: A cluster randomized controlled trial was conducted in 14 Australian schools. Schools were randomized to PreVenture, a brief personality-targeted selective intervention, comprising two 90-minute facilitator-led sessions delivered one week apart, or a control group (health education as usual). Only students who scored highly on one of four personality traits (anxiety sensitivity, negative thinking, impulsivity, sensation seeking) were included. Students completed online self-report questionnaires between 2012 and 2019: at baseline; post-intervention; 1-, 2-, 3-, 5.5- and 7-years post-baseline. Outcomes were past 6-months cannabis use, stimulant use (MDMA, methamphetamine or amphetamine) and cannabis-related harms.
    RESULTS: The sample comprised 438 adolescents (Mage=13.4 years; SD=0.47) at baseline. Retention ranged from 51% to 79% over the 7-years. Compared to controls, the PreVenture group had significantly reduced odds of annual cannabis-related harms (OR=0.78, 95% CI=0.65-0.92). However, there were no significant group differences in the growth of cannabis use (OR=0.84, 95% CI=0.69-1.02) or stimulant use (OR=1.07, 95% CI=0.91-1.25) over the 7-year period.
    CONCLUSIONS: PreVenture was effective in slowing the growth of cannabis-related harms over time, however owing to missing data over the 7-year trial, replication trials may be warranted to better understand the impact of the PreVenture intervention on cannabis and stimulant use among young Australians. Alternative implementation strategies, such as delivering the intervention in later adolescence and/or providing booster sessions, may be beneficial.
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  • 文章类型: Journal Article
    传统酸浸回收废旧锂离子电池受到严重污染的限制,复杂的技术,和Li2CO3的低纯度。针对传统酸浸工艺存在的问题和脱碳需求不断增加的问题,开发了一种通过不含酸或碱的简单浓缩沉淀法选择性碳化浸出Li和回收电池级Li2CO3的技术。CO2和还原剂的耦合可以通过降低过渡金属所需的还原能力和降低溶液的pH来有效地促进MCO3(M=Ni/Co/Mn)的沉淀和Li的选择性浸出。在1MPaCO2和20g/LNa2S2O3的条件下,L/S比为30mL/g,持续1.5h,获得了Li的最佳选择性浸出工艺。FT-IR,XRD,采用ICP-MS等方法揭示了层状正极材料碳化还原的多相界面反应机理,这表明还原剂Na2S2O3可以促进正极材料的晶格畸变和Li的有效分离。总之,提出了一种在近中性环境中使用一步CO2碳酸化回收方法选择性回收电池级Li2CO3的绿色经济方法。
    The recovery of spent lithium-ion batteries by traditional acid leaching is limited by serious pollution, complicated technology, and the low purity of Li2CO3. To address the problems of the traditional acid leaching process and increasing demand for decarbonization, a technique for the selective carbonation leaching of Li and the recovery of battery-grade Li2CO3 by a simple concentration precipitation process without acids or bases was developed. The coupling of CO2 and reducing agents could effectively promote the precipitation of MCO3 (M=Ni/Co/Mn) and the selective leaching of Li by decreasing the reducing capability needed for transition metals and decreasing the pH of the solution. The optimal selective leaching process of Li was obtained under 1 MPa CO2 with 20 g/L Na2S2O3 at an L/S ratio of 30 mL/g for 1.5 h. FT-IR, XRD, ICP-MS and other methods were used to reveal the multiphase interfacial reaction mechanism of the carbonation reduction of layered cathode materials, which indicated that the reducing agent Na2S2O3 could promote lattice distortion of the cathode materials and effective separation of Li. In summary, a green and economical method for the selective recovery of battery-grade Li2CO3 using a one-step method of CO2 carbonation recovery in a near-neutral environment was proposed.
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  • 文章类型: Journal Article
    背景:在牙科学生中实践和评估选择性龋齿去除技术仍然是许多牙科学校的挑战。这项研究的目的是利用3D评估技术,在指定的可接受偏差范围内,评估牙科学生进行选择性龋齿去除(SCR)的趋势。还确定了3D评估结果与讲师评估的常规标准之间的相关性。
    方法:五年级牙科学生(n=61)在咬合面和近端表面包含模拟深龋病变的3D打印牙齿上执行SCR任务。一位讲师使用常规分析规则评估了结果。使用3D分析软件对挖出的牙齿进行额外评估,并具有与标准空腔的指定可接受的偏差范围(±0.5mm)。平均均方根(RMS)值,代表学生准备的空腔和预定义的标准空腔之间的偏差,被记录下来。对于RMS值>0.5mm,定义了过度开挖的趋势。对于RMS值<0.5mm,则朝向欠开挖。
    结果:对于咬合,RMS的平均值(min-max)为0.27(0.18-0.40),对于近端腔,RMS的平均值为0.29(0.20-0.57)。在咬合(74%)和近端腔(87%)中都观察到牙科学生过度挖掘的趋势。对于咬合(R2=0.148,P=0.002)和近端腔(R2=0.107,P=0.010),RMS值与传统标准评分之间存在中度负相关。
    结论:3D评估技术有效地揭示了牙科学生龋齿去除技能的特定趋势。计算机化评估与传统方法的整合可能有助于教师向学生提供更客观和具体的反馈。鼓励进一步研究,以调查这种评估技术对提高学生在选择性龋齿去除技能方面的表现的影响。
    BACKGROUND: Practicing and assessment of selective caries removal techniques in dental students remain challenges in many dental schools. The aim of this study was to utilize a 3D assessment technique, within a designated acceptable range of deviation, to evaluate the tendency of dental students in performing selective caries removal (SCR). The correlation between 3D assessment results and the conventional rubric rated by an instructor was also determined.
    METHODS: Fifth-year dental students (n = 61) performed the SCR task on 3D-printed teeth containing simulated deep caries lesions in occlusal and proximal surfaces. One instructor assessed the results using a conventional analytic rubric. The excavated teeth were additionally evaluated using 3D analysis software with the designated acceptable range of deviations (± 0.5 mm) from the standard cavities. The average root mean square (RMS) value, representing the deviation between student-prepared cavities and the predefined standard cavities, was recorded. A tendency towards over-excavation was defined for RMS values > 0.5 mm, and towards under-excavation for RMS values < 0.5 mm.
    RESULTS: The mean (min-max) of RMS was 0.27 (0.18-0.40) for occlusal and 0.29 (0.20-0.57)for proximal cavities. A tendency of dental students toward over-excavation was observed in both occlusal (74%) and proximal cavities (87%). There was a moderate negative correlation between the RMS values and the traditional rubric scores for both occlusal (R2 = 0.148, P = 0.002) and proximal cavities (R2 = 0.107, P = 0.010).
    CONCLUSIONS: The 3D evaluation technique effectively revealed specific tendencies in dental students\' caries removal skills. The integration of computerized assessments with traditional methods could potentially assist the instructors in delivering more objective and specific feedback to students. Further research is encouraged to investigate the impact of this assessment technique on improving student performance in selective caries removal skills.
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