171 research outputs found
Cooperative dual catalysis with thiourea organocatalysts
No full textThiourea organocatalysis represents a versatile activation strategy in synthetic organic chemistry. By hydrogen-bonding interactions with neutral or anionic substrates and/or intermediates, thiourea organocatalysts can often direct the reaction pathways with promising levels of stereochemical control. This dissertation demonstrates the cooperative use of thiourea organocatalysts in combination with other types of catalysts in addressing challenging synthetic problems that are not realized by either type alone. Specifically, cooperative catalysis of thiourea and iminium organocatalysts enabled the first highly enantioselective direct oxa-Pictet–Spengler reactions under weakly acidic conditions. In comTbination with a transition metal catalyst, an acid–thiourea catalyst afforded highly enantioselective A3 reactions with secondary amines. Strong Brønsted acid was also applied cooperatively with thiourea organocatalyst, furnishing the direct reductive etherification reactions with a wide variety of substrates.Ph.D.Includes bibliographical referencesby Chenfei Zha
sj-docx-1-tam-10.1177_17588359221128356 – Supplemental material for Efficacy of neoadjuvant docetaxel + cisplatin chemo-hormonal therapy versus docetaxel chemo-hormonal therapy in patients with locally advanced prostate cancer with germline DNA damage repair gene alterations
No full textSupplemental material, sj-docx-1-tam-10.1177_17588359221128356 for Efficacy of neoadjuvant docetaxel + cisplatin chemo-hormonal therapy versus docetaxel chemo-hormonal therapy in patients with locally advanced prostate cancer with germline DNA damage repair gene alterations by Chenfei Chi, Jiazhou Liu, Liancheng Fan, Yinjie Zhu, Yanqing Wang, Jianjun Sha, Yiran Huang, Baijun Dong, Jiahua Pan and Wei Xue in Therapeutic Advances in Medical Oncology</p
Design of kneeling-sitting dual-use office chair based on ergonomics
Get PDFWith the popularity of paperless office methods, the proportion of people who use sitting posture as the main office posture is increasing[1], but at the same time, some disadvantages of sitting office are also highlighted. From the perspective of ergonomics, this article designs and analyses the structure and specific dimensions of the kneeling-sitting dual-use office chair. Based on the analysis of human spine curvature and lumbar electromyography, the effects of kneeling and sitting postures on human spine were compared. Then perfect the kneeling-sitting dual-use office chair that is more suitable for people’s office style
Numerical Analysis and Poromechanics Calculation for Saturated Mortar Involved with Sub-Freezing Temperature
No full textThe individual coupling processes of two-phase materials are controlled to some extent by damage theory. However, the existing theory is not sufficient to explain the effect of pore pressure on mortar materials under freeze-thaw action. In order to predict the resistance of saturated mortars during rapid cooling and to describe the physical behavior of the pore structure, the authors derived in detail the governing equations of saturated mortars during freezing in the framework of the pore elasticity theory and analyzed the sensitivity of physical parameters to the influence of temperature stresses by means of stress-strain calculations. In addition, the effects of phase change and latent heat of freezing on the local thermodynamic equilibrium are considered, and a mathematical model is established for quantitatively simulating the temperature distribution of the specimen. This model is reformulated and extended in the current work to intuitively reveal the effect of concrete dimensions on the temperature hysteresis effect. The results of the numerical model calculations show that during the freezing process, for the specimen with dimensions of 50 mm × 50 mm × 50 mm and a water-cement ratio of 0.6, the maximum temperature difference from center to surface is 10 °C, the maximum vertical strain on the surface is 4.27 × 10−4, and the maximum pore water pressure at the center of the specimen is 76 MPa. The model calculation results present a similar pattern to the physical interpretation and reference results, thus effectively evaluating the freezing damage process of saturated mortar
Fabrication of a high-strength lithium disilicate glass-ceramic in a complex glass system
Get PDFAbstractThe aim of this work was to develop a high-strength lithium disilicate glass-ceramic for dental restorative applications. A complex lithium disilicate glass composition was designed in the SiO2–Li2O–CaO–P2O5–ZrO2 glass system. Three sets of samples were employed to investigate the effects of heating profile, crystallization annealing temperature and holding time on the phase evolution, microstructure and mechanical properties. The results show that no lithium metasilicate was detected during the crystallization process. Semi-quantitative analysis reveals that the lithium disilicate glass-ceramics consist of 57–62wt% of rod-like lithium disilicate crystallites. A high flexural strength of 439±93MPa was observed in the glass-ceramic when it was subjected to two-stage annealing at 674°C. Additional higher temperature annealing stages were of little help for the improvement of bending strength, but did enhance the Vickers indentation fracture toughness (VIF) from 0.93 to 1.29MPa·m1/2. It is found that both the crystallization temperature and the holding time affect the phase transformation, morphology, and crystallite size of these glass-ceramics, but the crystallization temperature has a more profound effect than the holding time. The glass-ceramic developed in this study could be a good candidate for dental restorative applications, especially for posterior three-unit bridges
Learning structure of stereoscopic image for no-reference quality assessment with convolutional neural network
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A comparative analysis of sivelestat sodium hydrate and ulinastatin combination therapy in the treatment of sepsis with acute respiratory distress syndrome
No full textAbstract Objective This comparative analysis aimed to investigate the efficacy of Sivelestat Sodium Hydrate (SSH) combined with Ulinastatin (UTI) in the treatment of sepsis with acute respiratory distress syndrome (ARDS). Methods A control group and an observation group were formed with eighty-four cases of patients with sepsis with ARDS, with 42 cases in each group. The control group was intravenously injected with UTI based on conventional treatment, and the observation group was injected with SSH based on the control group. Both groups were treated continuously for 7 days, and the treatment outcomes and efficacy of both groups were observed. The Murray Lung Injury Score (MLIS), Sequential Organ Failure Assessment (SOFA), and Acute Physiology and Chronic Health Evaluation II (APACHE II) were compared. Changes in respiratory function, inflammatory factors, and oxidative stress indicators were assessed. The occurrence of adverse drug reactions was recorded. Results The total effective rate in the observation group (95.24%) was higher than that in the control group (80.95%) (P 0.05). MLIS, SOFA, and APACHE II scores in the observation group were lower than the control group (P 0.05). Conclusion The combination of SSH plus UTI improves lung injury and pulmonary ventilation function, and reduces inflammation and oxidative stress in patients with sepsis and ARDS
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