Nuclear Magnetic Resonance

核磁共振
  • 文章类型: Journal Article
    量子机器学习在许多重要任务中取得了显著进展。然而,许多量子机器学习算法很少考虑初始状态准备的门复杂度,使它们非端到端。在这里,针对节点嵌入问题,我们提出了一种将节点图的拓扑结构映射到嵌入向量的量子算法。得到的量子嵌入状态可以用作其他量子机器学习算法的输入。用O(log(N))个量子比特来存储N个节点的信息,我们的算法对于后续的量子信息处理不会失去量子优势。此外,由于使用了具有O(poly(log(N)))深度的参数化量子电路,结果状态可以作为一个有效的量子数据库。此外,我们探索了量子节点嵌入算法的测量复杂度,这是训练参数中的主要问题,并对该算法进行了扩展,以捕获节点间的高阶邻域信息。最后,我们通过实验证明了我们在核磁共振量子处理器上求解图模型的算法。
    Quantum machine learning has made remarkable progress in many important tasks. However, the gate complexity of the initial state preparation is seldom considered in lots of quantum machine learning algorithms, making them non-end-to-end. Herein, we propose a quantum algorithm for the node embedding problem that maps a node graph\'s topological structure to embedding vectors. The resulting quantum embedding state can be used as an input for other quantum machine learning algorithms. With O ( log ( N ) ) qubits to store the information of N nodes, our algorithm will not lose quantum advantage for the subsequent quantum information processing. Moreover, owing to the use of a parameterized quantum circuit with O ( poly ( log ( N ) ) ) depth, the resulting state can serve as an efficient quantum database. In addition, we explored the measurement complexity of the quantum node embedding algorithm, which is the main issue in training parameters, and extended the algorithm to capture high-order neighborhood information between nodes. Finally, we experimentally demonstrated our algorithm on an nuclear magnetic resonance quantum processor to solve a graph model.
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  • 文章类型: Journal Article
    碳材料被认为是吸附挥发性有机化合物(VOC)的有前途的吸附剂。然而,它们的吸附行为通常在环境条件下受到损害,归因于与水蒸气的竞争性VOCs吸附。在这项研究中,我们证明,通过在二维纳米片堆叠中引入更多的sp2-碳,可以有效地提高碳对甲苯的选择性。富含sp2碳(CNS-MCA)的多层碳纳米片表现出151°的H2O接触角,表示疏水性。动态吸附行为表明,即使在60%的相对湿度下,CNS-MCA仍保留其甲苯吸附量的71%(91mg/g)。密度泛函理论(DFT)计算,静态吸附研究,原位拉曼光谱,和时间分辨原位核磁共振(NMR)光谱共同表明,由于其芳环与sp2-碳之间的π-π*相互作用,甲苯表现出增强的吸附和选择性。相反,水的吸附减弱,归因于与sp2-碳相关的表面暴露的氢键的可用性降低以及多层石墨烯的固有疏水性质。这项研究扩展了在潮湿条件下增强VOCs吸附的新解决方案。
    Carbon materials are regarded as a promising adsorbent for the adsorption of volatile organic compounds (VOCs). However, their adsorption behaviors are usually compromised at ambient conditions, attributed to the competitive VOCs adsorption with water vapor. In this study, we demonstrated that the selectivity for toluene than water of carbon can be effectively enhanced by introducing more sp2-carbon with two-dimensional nanosheets stacked. The multilayer carbon nanosheets enriched with sp2-carbon (CNS-MCA) exhibit a 151° H2O-contact angle, indicating hydrophobicity. Dynamic adsorption behaviors revealed that CNS-MCA retain 71% of their toluene adsorption capacity (91 mg/g) even at 60% relative humidity. Density functional theory (DFT) calculations, static adsorption studies, in situ Raman spectroscopy, and time-resolved in situ nuclear magnetic resonance (NMR) spectroscopy collectively indicate that toluene exhibits enhanced adsorption and selectivity due to π-π* interactions between its aromatic rings and the sp2-carbon. Conversely, water adsorption is attenuated, attributed to the reduced availability of surface-exposed hydrogen bonds associated with sp2-carbon and the inherent hydrophobic nature of multilayer graphene. This study extends a novel solution for the enhancement of VOCs adsorption under humid conditions.
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  • 文章类型: Journal Article
    地下水中有机污染物的迁移和再分配是探索其动态演化和适当修复的基础和关键。冻融循环过程中自然发生的直径温度梯度导致地下水中有机污染物的不同行为。在这项研究中,基于多相流动力学将多孔介质中柴油的孔隙尺度分布定量划分为毛细管流体态(CFS)和自由流体态(FFS),采用低场核磁共振(LF-NMR)技术。根据LF-NMR结果,柴油的孔尺度分布不仅取决于冻融循环,还取决于温度梯度。与负温度梯度(例如解冻)相比,CFS中的柴油含量通常随着正温度梯度(例如冻结)而增加,而FFS中柴油的含量通常会降低。温度梯度对柴油孔隙尺度分布的这种依赖性与多孔介质的粒径正相关。此外,冻融循环过程中柴油的孔隙尺度分布受柴油运动粘度的影响。柴油含量与运动粘度之间存在指数关系,独立于冷冻或解冻过程。在冻结过程中,柴油从FFS迁移到CFS,而这种迁移在解冻过程中是相反的。柴油在冷冻和解冻过程之间的反向迁移导致柴油的空间再分配,这是由流体能量和毛细管力控制。本工作为寒区地下水污染治理提供了有意义的指导。
    The mobilization and redistribution of organic contaminants in groundwater is the basis and key to explore its dynamic evolution and appropriate remediation. The naturally occurring diametrical temperature gradient during freezing and thawing cycle leads to distinct behaviors of organic contaminants in groundwater. In this study, the pore-scale distribution of diesel oil in the porous media was quantitatively divided into capillary fluid state (CFS) and free fluid state (FFS) based on multiphase flow dynamics, employing low-field nuclear magnetic resonance (LF-NMR) technology. The pore-scale distribution of diesel oil depends not only on the freezing and thawing cycle but also on the temperature gradient according to LF-NMR results. The content of diesel oil in the CFS generally increases with a positive temperature gradient (e.g. freezing) compared to a negative temperature gradient (e.g. thawing), while the content of diesel oil in the FFS generally decreases. This dependence of the temperature gradient on pore-scale distribution of the diesel oil is positively correlated with the particle size of the porous medium. Furthermore, the pore-scale distribution of the diesel oil during the freezing and thawing cycle is influenced by the kinematic viscosity of the diesel oil. There is an exponential relationship between the diesel oil content and the kinematic viscosity, independent of the freezing or thawing process. During the freezing process, the diesel oil migrates from FFS to CFS, while this migration is reversed during the thawing process. The reverse migration of the diesel oil between the freezing and thawing processes leads to a spatial redistribution of the diesel oil, which is controlled by both the fluid energy and the capillary force. The present work provide meaningful guidance for the remediation of groundwater contamination in cold regions.
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  • 文章类型: Journal Article
    在超高场核磁共振(NMR)超导磁体的设计中,它通常需要球形体积(DSV)直径的高均匀磁场以获得高光谱分辨率。然而,由于磁体孔空间的限制,匀场技术提出了挑战,由于磁场分布的精确测量非常困难,特别是定制的微孔磁铁。在这项研究中,我们引入了一种主动匀场方法,该方法利用匀场线圈电流的迭代调整来基于频谱的半峰全宽(FWHM)改善磁场均匀性。所提出的方法可以确定匀场线圈的最佳电流集,通过收敛FWHM有效增强空间场均匀性。在25TNMR超导磁体上的实验验证证明了所提出方法的有效性。具体来说,有源匀场方法将10mmDSV的场均匀性从7.09ppm提高到2.27ppm,只有四个匀场线圈,为固体核磁共振和进一步的磁共振成像(MRI)实验提供了优越的磁场环境。此外,所提出的方法可以推广到需要高磁场均匀性的更定制的微孔磁体。
    In the design of ultrahigh field nuclear magnetic resonance (NMR) superconducting magnets, it typically requires a high homogeneous magnetic field in the diameter of spherical volume (DSV) to obtain high spectrum resolution. However, shimming technique presents challenges due to the magnet bore space limitations, as accurate measurement of magnetic field distribution is very difficult, especially for customized micro-bore magnets. In this study, we introduced an active shimming method that utilized iterative adjustment of shim coil currents to improve the magnetic field homogeneity based on the full width at half maximum (FWHM) of the spectrum. The proposed method can determine the optimal set of currents for shim coils, effectively enhancing spatial field homogeneity by converging the FWHM. Experimental validation on a 25 T NMR superconducting magnet demonstrated the efficacy of the proposed method. Specifically, the active shimming method improved the field homogeneity of a 10 mm DSV from 7.09 ppm to 2.27 ppm with only four shim coils, providing a superior magnetic field environment for solid NMR and further magnetic resonance imaging (MRI) experiment. Furthermore, the proposed method can be promoted to more customized micro-bore magnets that require high magnetic field homogeneity.
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  • 文章类型: Journal Article
    为了增强柑橘渣中黄色化合物的稳定性和耐光性,我们的研究成功地分离和纯化了5个化合物,利用超声波辅助提取和柱层析。确定的化合物包括亚油酸甲酯,邻苯二甲酸(2-乙基)己酯,1,3-二硬脂酰-2-油酰基甘油,6,6-双十四烷基-6,7-二羟基氮杂-2(3H)-酮,和n-十八碳-17-烯酸。从新鲜果渣中提取的单体,化合物1和2表现出与类黄酮和类胡萝卜素的结构相似性。相比之下,从发酵的果渣中分离出的聚合物,化合物3、4和5与新鲜的果渣化合物共享结构单元,表明向稳定的聚合物形式的转化。这表明微生物发酵过程不仅提高了柑橘果渣的价值,同时也为天然抗氧化黄色素的合成提供了一条有前景的途径,具有深远的理论和现实意义。
    To enhance the stability and light resistance of the yellow compounds in citrus pomace, our study successfully isolated and purified five compounds using ultrasonic-assisted extraction and column chromatography. The identified compounds include methyl linoleate, (2-ethyl)hexyl phthalate, 1,3-distearoyl-2-oleoylglycerol, 6,6-ditetradecyl-6,7-dihydroxazepin-2(3H)-one, and n-octadeca-17-enoic acid. The monomers extracted from fresh pomace, compounds 1 and 2, exhibit structural similarities to flavonoids and carotenoids. In contrast, the polymers isolated from fermented pomace, compounds 3, 4, and 5, share structural units with the fresh pomace compounds, indicating the transformation to stable polymeric forms. This suggests that the microbial fermentation process not only enhances the value of citrus pomace, but also provides a promising pathway for the synthesis of natural antioxidant yellow pigments with far-reaching theoretical and practical significance.
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  • 文章类型: Journal Article
    苹果肉倾向于变成粉状,在储存过程中通常会发生质地变质。在松脆和粉化阶段之间,对从“红江军”苹果的碳酸钠可溶性果胶(SSP)中分离出的三个子部分进行了比较研究,以揭示与粉化有关的质地变化。原位免疫荧光标记显示,半乳聚糖在果实粉化过程中在薄壁组织细胞壁中下降。FTIR分析,单糖组成和结构聚合物的结构表明,从SSP亚片段(SC0.0-P和S-M0.0-P)中丢失鼠李糖半乳糖醛酸-I(RG-I)可能与粘性密切相关。NMR光谱显示,在脆性阶段构成RG-I的SC0.0-P中α-Rhap残基重复单元中取代的半乳聚糖的丢失,随后在粉状阶段转化为S-M0.0-P,这可能与果胶的修饰密切相关。这些发现为理解“红江军”苹果在食用过程中SSP聚合物的潜在修饰提供了新的证据。
    Apple flesh tends to turn mealy and textural deterioration commonly occurs during storage. The comparative investigation of three sub-fractions separated from sodium carbonate-soluble pectin (SSP) of \'Hongjiangjun\' apples between crisp and mealy stages was performed to unveil the textural alterations related to mealiness. In situ immunofluorescence labelling showed that galactans declined in parenchyma cell walls during the fruit mealiness. FTIR analysis, monosaccharide compositions and structural polymers configurated that loss of rhammogalacturonan-I (RG-I) from SSP sub-fragments (SC0.0-P and S-M0.0-P) might be closely involved in the mealiness. The NMR spectroscopy revealed that loss of the substituted galactans from α-Rhap residues repeat unit in SC0.0-P constituting RG-I in crisp stage that subsequently converted to S-M0.0-P in mealy stage might be closely associated with the modifications of pectin in cell walls during mealiness. These findings provided novel evidence for understanding the underlying modifications of SSP polymers during the mealiness of \'Hongjiangjun\' apples.
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  • 文章类型: Journal Article
    目的:本研究旨在揭示Botrychiumternatum(Thunb。)Sw。(BT)抗特发性肺纤维化(IPF),并初步分析其对博来霉素诱导的IPF大鼠的潜在机制。
    方法:通过组织病理学结合生化指标评估体内纤维化进展的抑制作用。此外,利用基于1H-核磁共振的代谢组学结合多变量统计分析研究了代谢调控机制.
    结果:首先,生化分析表明,BT显着抑制肺组织中羟脯氨酸和转化生长因子β1的表达。其次,Masson三色染色和苏木精、伊红染色显示,BT能显著改善受损肺的结构,显著抑制胶原纤维的增殖和细胞外基质的沉积。最后,血清代谢组学分析表明,BT可能通过协同调节酪氨酸代谢发挥抗纤维化作用;酪氨酸和色氨酸生物合成;酮体的合成和降解。
    结论:我们的研究不仅在代谢水平上阐明了BT抗IPF的潜在抗纤维化机制,而且为BT作为一种有效的抗纤维化药物的开发提供了理论依据。
    OBJECTIVE: This study aimed to reveal the anti-fibrotic effects of Botrychium ternatum (Thunb.) Sw. (BT) against idiopathic pulmonary fibrosis (IPF) and to preliminarily analyze its potential mechanism on bleomycin-induced IPF rats.
    METHODS: The inhibition of fibrosis progression in vivo was assessed by histopathology combined with biochemical indicators. In addition, the metabolic regulatory mechanism was investigated using 1H-nuclear magnetic resonance-based metabolomics combined with multivariate statistical analysis.
    RESULTS: Firstly, biochemical analysis revealed that BT notably suppressed the expression of hydroxyproline and transforming growth factor-β1 in the pulmonary tissue. Secondly, Masson\'s trichrome staining and hematoxylin and eosin showed that BT substantially improved the structure of the damaged lung and significantly inhibited the proliferation of collagen fibers and the deposition of extracellular matrix. Finally, serum metabolomic analysis suggested that BT may exert anti-fibrotic effects by synergistically regulating tyrosine metabolism; phenylalanine, tyrosine and tryptophan biosynthesis; and synthesis and degradation of ketone bodies.
    CONCLUSIONS: Our study not only clarifies the potential anti-fibrotic mechanism of BT against IPF at the metabolic level but also provides a theoretical basis for developing BT as an effective anti-fibrotic agent.
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  • 文章类型: Journal Article
    背景:在种族和地理上不同的人群中,全面的血液脂蛋白谱及其与冠心病(CHD)的关系仍未得到充分研究。
    结果:我们在3438名个体(1719对)中进行了冠心病的巢式病例对照研究,包括1084名美国白人(542对),1244美国黑人(622对),和1110名中国成年人(555对)。我们检查了36种血浆脂质,脂蛋白,和载脂蛋白,核磁共振波谱测量,根据人口统计学,所有参与者和亚组中的冠心病事件,生活方式,和代谢健康状况,使用条件或无条件逻辑回归校正潜在的混杂因素。常规测量血脂,也就是说,总胆固醇,甘油三酯,低密度脂蛋白胆固醇,高密度脂蛋白胆固醇,每个都与冠心病相关,所有参与者的比值比(ORs)分别为1.33、1.32、1.24和0.79/1-SD.17种脂蛋白生物标志物显示出数字上比常规脂质更强的关联,所有参与者中每1-SD的ORs范围为1.35至1.57,OR为阴性0.78(所有错误发现率<0.05),包括载脂蛋白B100与载脂蛋白A1的比率(OR,1.57[95%CI,1.45-1.7]),低密度脂蛋白甘油三酯(OR,1.55[95%CI,1.43-1.69]),和载脂蛋白B(OR,1.49[95%CI,1.37-1.62])。所有这些关联在种族群体和其他按年龄定义的亚组之间是显著和一致的,性别,吸烟,肥胖,和代谢健康状况,包括常规测量的脂质水平正常的个体。
    结论:我们的研究强调了几种脂蛋白生物标志物,包括载脂蛋白B/载脂蛋白A1比率,载脂蛋白B,和低密度脂蛋白甘油三酯,与冠心病事件密切相关。我们的结果表明,全面的脂蛋白测量可以补充标准脂质面板,以告知不同人群的CHD风险。
    BACKGROUND: Comprehensive blood lipoprotein profiles and their association with incident coronary heart disease (CHD) among racially and geographically diverse populations remain understudied.
    RESULTS: We conducted nested case-control studies of CHD among 3438 individuals (1719 pairs), including 1084 White Americans (542 pairs), 1244 Black Americans (622 pairs), and 1110 Chinese adults (555 pairs). We examined 36 plasma lipids, lipoproteins, and apolipoproteins, measured by nuclear magnetic resonance spectroscopy, with incident CHD among all participants and subgroups by demographics, lifestyle, and metabolic health status using conditional or unconditional logistic regression adjusted for potential confounders. Conventionally measured blood lipids, that is, total cholesterol, triglycerides, low-density lipoprotein-cholesterol, and high-density lipoprotein-cholesterol, were each associated with incident CHD, with odds ratios (ORs) being 1.33, 1.32, 1.24, and 0.79 per 1-SD increase among all participants. Seventeen lipoprotein biomarkers showed numerically stronger associations than conventional lipids, with ORs per 1-SD among all participants ranging from 1.35 to 1.57 and a negative OR of 0.78 (all false discovery rate <0.05), including apolipoprotein B100 to apolipoprotein A1 ratio (OR, 1.57 [95% CI, 1.45-1.7]), low-density lipoprotein-triglycerides (OR, 1.55 [95% CI, 1.43-1.69]), and apolipoprotein B (OR, 1.49 [95% CI, 1.37-1.62]). All these associations were significant and consistent across racial groups and other subgroups defined by age, sex, smoking, obesity, and metabolic health status, including individuals with normal levels of conventionally measured lipids.
    CONCLUSIONS: Our study highlighted several lipoprotein biomarkers, including apolipoprotein B/ apolipoprotein A1 ratio, apolipoprotein B, and low-density lipoprotein-triglycerides, strongly and consistently associated with incident CHD. Our results suggest that comprehensive lipoprotein measures may complement the standard lipid panel to inform CHD risk among diverse populations.
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  • 文章类型: Journal Article
    作为最恶性的肿瘤,即使在少数可以接受根治性手术的患者中,胰腺癌的预后也不理想。作为一种高度异质性的肿瘤,化疗耐药是导致胰腺癌疗效下降和术后复发的主要因素。在这项研究中,基于核磁共振(NMR)的代谢组学应用于胰腺导管腺癌(PDAC)的血清代谢特征的鉴定和潜在的生物标志物的筛选。同时监测术后化疗期间不同CA19-9水平患者的代谢变化,并进行比较,以确定可能影响化疗疗效的差异代谢物。最后,筛选了19种潜在的血清生物标志物以用于PDAC的诊断,PDAC的两种CA19-9分层之间的显着代谢差异涉及能量代谢,脂质代谢,氨基酸代谢,和柠檬酸代谢。代谢途径的富集分析揭示了PDAC和化疗的六个共享途径,如丙氨酸,天冬氨酸和谷氨酸代谢,精氨酸生物合成,谷氨酰胺和谷氨酸代谢,柠檬酸盐循环,丙酮酸代谢,和糖酵解/糖异生。PDAC代谢特征与化疗代谢反应的相似性为PDAC患者术后化疗获益的临床预测提供了参考依据。
    As the most malignant tumor, the prognosis of pancreatic cancer is not ideal even in the small number of patients who can undergo radical surgery. As a highly heterogeneous tumor, chemotherapy resistance is a major factor leading to decreased efficacy and postoperative recurrence of pancreatic cancer. In this study, nuclear magnetic resonance (NMR)-based metabolomics was applied to identify serum metabolic characteristics of pancreatic ductal adenocarcinoma (PDAC) and screen the potential biomarkers for its diagnosis. Metabolic changes of patients with different CA19-9 levels during postoperative chemotherapy were also monitored and compared to identify the differential metabolites that may affect the efficacy of chemotherapy. Finally, 19 potential serum biomarkers were screened to serve the diagnosis of PDAC, and significant metabolic differences between the two CA19-9 stratifications of PDAC were involved in energy metabolism, lipid metabolism, amino acid metabolism, and citric acid metabolism. Enrichment analysis of metabolic pathways revealed six shared pathways by PDAC and chemotherapy such as alanine, aspartate and glutamate metabolism, arginine biosynthesis, glutamine and glutamate metabolism, citrate cycle, pyruvate metabolism, and glycogolysis/gluconeogeneis. The similarity between the metabolic characteristics of PDAC and the metabolic responses to chemotherapy provided a reference for clinical prediction of benefits of postoperative chemotherapy in PDAC patients.
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  • 文章类型: Journal Article
    岩石断裂是由微观裂纹的萌生和扩展引起的宏观断裂过程。因此,通过研究中孔断裂结构在高频振动载荷作用下的演化规律,了解超声振动下岩石的损伤和断裂机理至关重要。正如本研究中所探讨的那样。对直径为50mm,高度为100mm的标准红砂岩样品进行了超声高频振动测试。在超声振动激发的不同阶段对岩石样品进行NMR和CT扫描,以获得每层相应的横向弛豫时间(T2)光谱和CT扫描图像。核磁共振测试结果表明,在高频振动载荷作用下,岩石内部会形成较小的孔隙,在微孔中观察到明显的膨胀。基于二维CT图像的三维重建分析表明,毛孔数量增加了145.56%,122.67%,98.87%,分别,对于上层,中间,和岩石的下部经过120s的超声振动激励;此外,最大孔容增加239.42%,109.16%,18.99%,分别,在此期间,这些地区也是如此。这些发现有助于更深入地了解暴露于高频振动载荷时岩石破碎的机理。
    Rock fracture is a macroscopic fracturing process resulting from the initiation and propagation of microscopic cracks. Therefore, it is crucial to comprehend the damage and fracture mechanism of rock under ultrasonic vibration by investigating the evolutionary pattern of the meso-pore fracture structure in response to high-frequency vibrational loads, as explored in this study. Standard red sandstone samples with a diameter of 50 mm and height of 100 mm were subjected to ultrasonic high-frequency vibration tests. NMR and CT scans were conducted on the rock samples at different stages of ultrasonic vibration excitation to obtain the corresponding transverse relaxation time (T2) spectra and CT scan images for each layer. The NMR test results revealed that smaller pores formed within the rock under high-frequency vibration loads, with a noticeable expansion observed in micropores. Three-dimensional reconstruction analysis based on two-dimensional CT images demonstrated an increase in pore count by 145.56%, 122.67%, and 98.87%, respectively, for the upper, middle, and lower parts of the rock after 120 s of ultrasonic vibration excitation; furthermore, the maximum pore volume increased by 239.42%, 109.16%, and 18.99%, respectively, for these regions during this period as well. These findings contribute towards a deeper understanding regarding the mechanisms underlying rock fragmentation when exposed to high-frequency vibrational loads.
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