Kinetic Resolution of Acyclic Tertiary Propargylic Alcohols by NHC-Catalyzed Enantioselective Acylation.

We report herein an efficient NHC-catalyzed kinetic resolution of acyclic tertiary propargylic alcohols that provides them in high to excellent enantioselectivity. This is the first example of kinetic resolution realized by enantioselective acylation. The recovered enantioenriched alcohols can be facilely converted into other valuable compounds such as densely functionalized tertiary alcohols and carbmates in high yields and excellent stereopurity. Density functional theory calculations were performed to determine the reaction mechanism and to understand the origin of enantiodiscrimination.

Protective Effects of Mesenchymal Stem Cells Against Central Nervous System Injury in Heat Stroke.

BACKGROUND: Heatstroke (HS) is a serious disease caused by central nervous system (CNS) injuries, such as delirium, convulsion, and coma. Currently, mesenchymal stem cells (MSCs) have demonstrated novel neuroprotective effects; therefore, this research explores the neuroprotective effects and mechanisms of MSCs against HS injury. METHODS: HS rat models were induced in a 40°C and 65% humidity environment until the rectal temperature reached 42°C. The verified HS injury model rats were divided into the HS and MSCs-treated groups. Each rat in the treated group was infused with 1x106 MSCs suspended in 0.3 ml physiological saline via the tail vein. The HS- or MSCs-treated rats were further divided into early-stage (3d) and late-stage (28d). HS rat models were induced by a high-temperature and high-humidity environment at a specific time, the mortality was analyzed, and an automatic biochemical analyzer measured levels of liver and kidney function indicators in the blood. The neurons' morphologic changes were observed through Nissl staining, and neurological deficit scores were performed. Moreover, the levels of inflammatory factors in brain tissue were measured using a multi-cytokine detection platform, and the expression of BDNF, phosphorylated TrkB and P38 were detected by the Western Bolt. RESULTS: MSCs injection significantly reduced mortality and alleviated liver and kidney function. Moreover, the neurological deficit and neuronic edema of the hippocampus caused by HS at 3d and 28d were significantly ameliorated by MSCs administration. Specifically, the injection of MSCs inhibited high levels of interleukin (IL)-1ß, IL-6, tumor necrosis factor-α (TNF-α), and IL-17A caused by HS but elevated the levels of IL-10 and IL-13 in the early period (3d); while in the later period (28d), MSCs significantly increased the levels of IL-10 and IL-13 continuously and inhibited the high level of IL-17A. Furthermore, MSCs injection increased the expressions of BDNF and phosphorylated TrkB (BDNF receptor), meanwhile inhibiting the expression of phosphorylated P38 (inflammatory factor) in the brains of HS rats in the early period (3d) but had no significant influence on the later period (28d). CONCLUSION: These results suggested that MSCs injection may provide therapeutic effects for HS in rats by improving liver and kidney function and reducing CNS damage. Moreover, MSCs injection inhibited the brain inflammatory response of HS rats, and the BDNF-TrkB and P38/MAPK signal pathways may be involved, providing a potential mechanism for HS therapy by MSCs administration.

Development of a high-power pulse-forming network Marx generator with a long pulse duration.

To meet the application needs for producing long-pulse electron beams and high-power microwaves, a pulse-forming network Marx generator with a pulse duration of 260 ns is presented in this paper. This generator is composed of 20 stages of pulse-forming network modules. Each module is formed with nine capacitors connected in parallel. The generator functions at 44 kV, which is lower than the rated voltage of the mica paper capacitor, to improve the lifetime. The impedance of the generator is designed to reach 45 Ω. To avoid the strong coupling between the adjacent stages, the physical layout of the generator adopts a zigzag design. The generator is housed in a gas pressurized vessel of 600 mm in diameter and 580 mm in length. Across a 50 Ω load, it can deliver quasi-rectangular pulses with a pulse duration of 260 ns and an amplitude of 500 kV for a single shot. The output pulse features a plateau duration of 160 ns and a leading edge of 45 ns. In burst mode, it can steadily output ten pulses of 450 kV at a repetition rate of 10 Hz on either a resistive load or a diode.

A compact repetitive high energy-density accelerator HEART-20 based on propylene carbonate pulse forming line.

The development of pulsed power technology requires an electron beam accelerator with high output power and repetitive operation. A compact repetitive electron beam accelerator based on a pulse transformer and a pulse forming line of high permittivity liquid, as an essential type of one, has attracted extensive attention at the present time. In this paper, the development of a compact high energy-density electron beam accelerator, viz., HEART-20, based on a propylene carbonate (PC) forming line is presented. The accelerator HEART-20 consists of a primary energy source, a pulse transformer, a PC pulse forming line, a gas spark gap switch, and a vacuum diode. First, the operation principle of the accelerator is described. Second, the design of the accelerator's parameters is presented. A pulse transformer is developed for rapid charging of the PC-filled pulse forming line. The coupling coefficient is above 0.9, the voltage ratio is about 200, and the operation voltage is about 800 kV. Third, the energy storage characteristics of PC are investigated. The insulation characteristics of PC under positive charging voltage are found to perform better than those under negative charging voltage. The insulating strength of PC can be improved by pressurization. Finally, the development of the accelerator HEART-20 is presented. Across a vacuum diode load, it can steadily operate at a 20 GW output power in 5 Hz rep-rate. Moreover, it can drive a magnetically insulated line oscillator to produce about 2.0 GW microwave. These findings provide a good foundation for the development of a rep-rate intensive electron beam accelerator with promising applications for the future.

Clinicopathological Features of Inflammatory Myofibroblastic Tumor in the Breast.

Inflammatory myofibroblastic tumor (IMT) is a mesenchymal spindle cell tumour with low malignant potential which is extremely rare in breasts. Because of the lack of typical imaging and clinical characteristics of IMT, it is easy to misdiagnose before operation. We now report a case of a 37-year-old woman presenting with a mass in her left breast. Ultrasound showed a well-circumscribed lesion in the lower outer quadrant. The patient underwent lumpectomy, and histopathology revealed a tumor which was composed of fusiform cells and inflammatory cells. Immunohistochemistry (IHC) showed tumor cells are positive for vimentin, ALK, BCL2, and SMA. The FISH test demonstrated ALK (2p23) chromosomal translocation (ALK positive). The final diagnosis of breast IMT was rendered with nonclassical morphology. Postoperative 30-month follow-up no evidence showed residual tumor or recurrence. As a very rare tumor, breast IMT could be easily misdiagnosed clinically and pathologically. Complete surgical resection of the tumor is preferred, and it has the risk of recurrence and metastasis.

A battery-powered over-voltage triggering method for two-electrode spark gaps in Marx generator.

Triggered gas switches with trigger electrodes, such as three-electrode spark switches and trigatron type spark switches, have been widely used in repetitive operating Marx generators due to their large current flowing capability. However, the ablation of trigger electrodes during repetitive operation is inevitable, which reduces the working life of triggered gas switches. In this paper, we introduced an over-voltage triggering method for two-electrode spark switches by replacing one of the charging inductors of the Marx generator with a pulse generator. The experimental results showed that a high-voltage trigger pulse with an amplitude of 60 kV and a rising speed of 7.65 kV/100 ns was obtained from a single stackable module with a 12 V lithium battery pack as the energy source. Due to the absence of trigger electrodes, the triggering method is beneficial to extend the lifetime of switches and realize a maintenance-free repetitive operating Marx generator.

NDC1 is a Prognostic Biomarker and Associated with Immune Infiltrates in Colon Cancer.

BACKGROUND: Colon cancer is one of the most lethal cancers in the world. NDC1 is a crucial membrane-integral nucleoporin of nuclear pore complexes. The clinical significance of NDC1 in colon cancer has not been demonstrated to date. Therefore, we determined to evaluate the association between NDC1 and colon cancer using the open-access database. METHODS: The TCGA data of colon cancer were extracted to determine the relationship between NDC1 and the clinical characterization. We assessed the predictive role of NDC1 expression in the survival of patients with colon cancer. Univariate and multivariate Cox proportional hazard models were applied to analyze the association between the clinical factors and prognosis. The TIMER database was used to describe the association between immune cell infiltration and specific gene expression in the colon cancer context. Gene set enrichment analysis (GSEA) was performed based on the TCGA dataset. RESULTS: A total of 445 colon cancer patients with complete clinical information were included. NDC1 expression was significantly up-regulated in colon cancer tissues compared to adjacent normal tissues. Univariate and multivariate Cox regression analyses showed that NDC1 was an independent prognostic factor. Patients with a higher level of NDC1 expression tend to survive longer compared to those with a lower level of NDC1 expression. The level of the NDC1 expression is significantly associated with TNM stages. Furthermore, we constructed a nomogram to predict the prognosis by using NDC1 as a factor. The expression of NDC1 was significantly associated with infiltration of B cell, CD8+T cells, macrophages, neutrophils, and dendritic cells in colon cancer lesions. Additionally, NDC1 was predominantly enriched in KRAS-related signaling pathways by GSEA. CONCLUSION: NDC1 can serve as a prognostic biomarker, which is negatively correlated with aggressiveness and positively associated with immune infiltrates of colon cancer.

Antagonistic Strain Bacillus amyloliquefaciens XZ34-1 for Controlling Bipolaris sorokiniana and Promoting Growth in Wheat.

Common root rot, caused by Bipolaris sorokiniana, is one of the most prevalent diseases of wheat and has led to major declines in wheat yield and quality worldwide. Here, strain XZ34-1 was isolated from soil and identified as Bacillus amyloliquefaciens based on the morphological, physiological, biochemical characteristics and 16S rDNA sequence. Culture filtrate (CF) of strain XZ34-1 showed a high inhibition rate against B.sorokiniana and had a broad antifungal spectrum. It also remarkably inhibited the mycelial growth and spore germination of B. sorokiniana. In pot control experiments, the incidence and disease index of common root rot in wheat seedlings were decreased after treatment with CF, and the biological control efficacy was significant, up to 78.24%. Further studies showed XZ34-1 could produce antifungal bioactive substances and had the potential of promoting plant growth. Lipopeptide genes detection with PCR indicated that strain XZ34-1 may produce lipopeptides. Furthermore, activities of defense-related enzymes were enhanced in wheat seedlings after inoculation with B.sorokiniana and treatment with CF, which showed induced resistance could be produced in wheat to resist pathogens. These results reveal that strain XZ34-1 is a promising candidate for application as a biological control agent against B.sorokiniana.

Low-impedance high-power pulsed generator based on forming line with built-in Tesla transformer.

In order to meet the application needs of gyromagnetic nonlinear transmission lines, a pulsed power generator is required to output short duration pulses with a fast rising edge in high repetitive-rate mode. In this paper, a low-impedance high-power pulsed generator based on the forming line with a built-in Tesla transformer is explored and developed. The generator includes a 14 Ω coaxial forming line, a SF6/N2 gas switch, and a resistive dummy load, which can steadily operate in 100 Hz mode and suits the needs above. The pulsed forming line adopts transformer oil as the insulation medium and has a large shell radius and short length to reduce impedance. It has been verified by CST simulation that a relatively high coupling coefficient (0.93) can be achieved when the length-radius ratio is 3.2. The maximum forming line charging voltage is -600 kV in single-shot mode, while the charging voltage is -520 kV in repetitive-rate mode. The output pulse duration is 13 ns with a 4 ns rising edge, and its amplitude for a 10 Ω load is -220 kV at a repetition rate of 100 Hz. The experimental results showed the feasibility of the low-impedance nanosecond periodically pulsed generator based on an oil forming line charged from the high-coupling Tesla transformer. These efforts expand the technical route of the pulse forming line with a built-in Tesla transformer and set a good foundation for its application in the future.

Investigation of comb-type pulse forming line with low impedance.

Development of pulsed power technology is toward higher power, longer duration, and more compact structures. Compact coaxial propylene carbonate pulse forming lines are widely used in the application of pulsed power systems. In order to further lengthen the duration and decrease the geometrical sizes of pulsed power systems, a comb-type pulse forming line is adopted. It is a slow-wave structure with a comb-type inner electrode. In this paper, the operation principle, theoretical analysis, numerical simulation, and experimental investigation of the comb-type forming line are carried out, respectively. First, the operation principle is briefly introduced. The principle to increase the duration is explained. Second, the theoretical analyses about the dispersion relation are proposed. Third, the PSpice model is built by the L-C network. Based on the calculated parameters, the electrical circuit is simulated. A Computer Simulation Technology (CST) model is also built, which allows for a straightforward coupling of electric and magnetic (EM) simulation and circuit simulation. Finally, the comb-type pulse forming line is experimentally tested and verified. For the comb-type propylene carbonate forming line with a 67 cm length to replace the traditional coaxial one, it has an impedance of 8 Ω and a duration of 64 ns. Experimental data on its test results are given. The experimental results are in accordance with the numerical simulations. The investigation approved the comb-type pulse forming line feasible and set a solid foundation for its application in the pulsed power system.

INS/GPS/LiDAR Integrated Navigation System for Urban and Indoor Environments Using Hybrid Scan Matching Algorithm.

This paper takes advantage of the complementary characteristics of Global Positioning System (GPS) and Light Detection and Ranging (LiDAR) to provide periodic corrections to Inertial Navigation System (INS) alternatively in different environmental conditions. In open sky, where GPS signals are available and LiDAR measurements are sparse, GPS is integrated with INS. Meanwhile, in confined outdoor environments and indoors, where GPS is unreliable or unavailable and LiDAR measurements are rich, LiDAR replaces GPS to integrate with INS. This paper also proposes an innovative hybrid scan matching algorithm that combines the feature-based scan matching method and Iterative Closest Point (ICP) based scan matching method. The algorithm can work and transit between two modes depending on the number of matched line features over two scans, thus achieving efficiency and robustness concurrently. Two integration schemes of INS and LiDAR with hybrid scan matching algorithm are implemented and compared. Real experiments are performed on an Unmanned Ground Vehicle (UGV) for both outdoor and indoor environments. Experimental results show that the multi-sensor integrated system can remain sub-meter navigation accuracy during the whole trajectory.