A Stereospecific Pd-Catalyzed Suzuki Cross-Coupling Reaction and a Statistical Study of the Ligand\u27s Role in Stereoselection

The development of palladium-catalyzed carbon-carbon cross-coupling reactions has profoundly influenced the manner through which we approach the synthesis of complex organic molecules. Among established cross-coupling reactions, which include Kumada, Negishi, and Stille reactions, the Suzuki cross-coupling reaction exhibits particularly wide functional group compatibility, while employing non-toxic, air-stable organoboron nucleophiles. Conventional studies of Pd-catalyzed Suzuki cross-coupling reactions have focused on C(sp2)-C(sp2) cross-coupling reactions, which result in the formation of planar products. Conceptually, the use of C(sp3) (secondary) nucleophiles would enable the reliable manipulation of organic molecules in three dimensions. However, this process has not been achievable due to the slow rate of transmetallation of secondary alkylboron nucleophiles, and the subsequent isomerization of alkyl units following transmetallation to palladium. Herein, we describe the development of a general process for Pd-catalyzed cross-coupling reactions involving alkylboron nucleophiles using racemic and enantioenriched alkylboron nucleophiles. The origin of stereoselectivity was investigated through correlation of parameterized phosphine properties to stereochemical outcomes. A stereodivergent cross-coupling reaction was developed in which stereoretention and stereoinversion could be selectively achieved through the proper choice of ligand. A broad range of aryl chloride or bromide and inactivated secondary alkylboron nucleophiles are applicable in these reactions

PO-092 Effects of hypoxic exercise on weight loss and lipid metabolism in overweight/obese men

Objective  In recent years, people's diet has undergone tremendous changes. Excessive energy intake combined with insufficient exercise has made obesity a serious social problem. This study aims to achieve different training conditions under hypoxia and normoxia，conducting a six-week exercise training for obese overweight people. Comparing the difference in exercise weight loss between obese and overweight people in the normoxia training environment compared with hypoxia intervention, and the effect of hypoxic intervention on lipid metabolism indicators in overweight and obese people. Methods  A total of 40 male overweight/obese subjects were enrolled in the study, aged 18-47 years, with no abnormal physical examination and no motor contraindications. The overweight standard is BMI≥24, and the obesity standard is BMI≥28.All subjects were randomly matched according to body weight, divided into hypoxia group and normoxia group, and exercised for 6 weeks, training 3 times a week, one time every two days. Sports training includes 30 minutes of strength training and 30 minutes of aerobic endurance training. There are 5 minutes of warm-up and finishing activities before and after training. The strength training tool is dumbbell, and the weight of the corresponding 12RM is selected according to the exercise ability of the subject, and 8 exercises are performed. They are dead lift, upright row, squat, shoulder press, calf Jump, advance lunge, biceps curl and triceps extension. Those 8 movements are divided into two small loop trainings, which complete two large groups (each small loop is completed twice).Aerobic endurance training is done using a treadmill with a slope of 0°and the speed is adjusted according to the range of the target heart rate. The target heart rate is 60%-70% at the maximum heart rate. The maximum heart rate calculation method is (220-age).The hypoxic group is equipped with a suction-type atmospheric hypoxic device and is operated under a low-oxygen environment. The oxygen content of the inhaled mixed gas is 16%, the normoxic group was exercised under normoxic conditions. Nutritional education was given to all subjects prior to the start of exercise intervention, but diet was not restricted during the intervention. Before and after intervention, height and weight were measured, and BMI was calculated. Fasting venous blood was used to detect total cholesterol (TC), total triglyceride (TG), high-density lipoprotein cholesterol (HDL-C), and low-density lipoprotein cholesterol (LDL-C), leptin (LEP) and adiponectin (ADPN). All test results are expressed as mean ± standard deviation. Comparison of data between groups, using nonparametric Mann-Whitney U test. Comparison of intra-group data, using non-parametric Wilcoxon matching for symbol level checking, the significance level was P<0.05, and the very significant level was P<0.01. Results (1) After the intervention, the body weight of both groups decreased, and the Δbody weight (P<0.01), body weight change rate (P<0.01) and BMI change rate (P<0.01) in the hypoxic group were significantly higher than normal oxygen group. (2) TG, TC and LDL-C decreased in the hypoxic group, and there was a significant difference between TG and TC before intervention (P<0.01). There was no significant difference in TG, TC and LDL-C between the normoxic group and the intervention group (P>0.05). (3) The TG change rate (P<0.05), TC change rate (P<0.05) and LDL-C change rate (P<0.01) in the hypoxic group were significantly higher than those in the normoxic group. (4) HDL-C in hypoxia group and normoxia group decreased after intervention, and there was no significant difference between the two groups (P>0.05), and there was no difference between HDL-C(P>0.05). (5) LEP and ADPN in the hypoxic group increased after intervention, but there was no significant difference compared with before intervention (P>0.05). LEP and ADPN in the normoxic group decreased after intervention, and there was no difference between the LEP change rate and the ADPN change rate (P>0.05). Conclusions Under hypoxic intervention, the weight change, rate of change, and BMI change rate of overweight people were larger than those of the normoxic group. Body weight, BMI is a direct indicator of the degree of obesity in individuals. The hypoxic weight loss intervention shows greater advantages than the normoxic group from the intuitive data, which can help overweight and obese people to lose more weight under the same training load and intensity. After six weeks of training, in the hypoxic group, TC, TG and LDL-C decreased, and HDL-C increased. However, in the normoxic control group, these indicators did not show similar significant changes. It shows that through hypoxia intervention combined with exercise training, it can prevent and alleviate various chronic diseases caused by obesity more effectively, such as atherosclerosis. The other two indicators, LEP and ADPN, did not change significantly in both hypoxic and normoxic training. Conjecture there may be other mechanisms affecting the expression levels of these two hormones in the body. In summary, the researchers think the hypoxic exercise to lose weight is better than normal oxygen exercise, and it has a greater impact on most lipid metabolism indicators, which can stimulate most lipid metabolism to produce benign changes

Electronic Properties of a New All-Inorganic Perovskite TlPbI\u3csub\u3e3\u3c/sub\u3e Simulated by the First Principles

All-inorganic perovskites have been recognized as promising photovoltaic materials. We simulated the perovskite material of TlPbI3 using ab initio electronic structure calculations. The band gap of 1.33 eV is extremely close to the theoretical optimum value. Compared TlPbI3 with CsPbI3, the total energy (−3980 eV) of the former is much lower than the latter. The partial density of states (PDOS) of TlPbI3 shows that a strong bond exists between Tl and I, resulting in the lower total energy and more stable existence than CsPbI3

Simulation of fluid flow and inclusion removal in five-flow T-type tundish with porous baffle wall

To solve the instability of liquid steel in the continuous casting process and the inconsistent flaw detection of heavy rail steel, steel flow control was studied numerically in a tundish with a po-rous baffle wall by using the fluid dynamics software Fluent. The opening plan of the baffle wall was improved through orthogonal optimization design of holes in porous baffle wall. The test condition was set to a left inclination angle α1 = 22°, a right inclination angle α2 = 48°, an upward elevation angle β = 30°, and an aperture d = 70 mm. The simulation results of optimization scheme showed that the uniformity of the flow and temperature fields had been significantly improved, and the flow in each strand became consistent. The maximum temperature difference was 21 K in tundish, and the maximum temperature difference of three outlets was only 1.7 K. The dead zone volume was reduced by 10.0 % compared to the original tundish, and the plug flow volume was increased by 14.2 %. Comparing the removal efficiency of Al2O3 inclusions with different size, the results showed that the removal efficiency of 10 μm and 30 μm smaller inclusions was above 87 %. The removal rate of ≥ 50 μm larger inclusions also remained about 95 %

Designing reliable cyber-physical systems overview associated to the special session at FDL’16

CPS, that consist of a cyber part – a computing system – and a physical part – the system in the physical environment – as well as the respective interfaces between those parts, are omnipresent in our daily lives. The application in the physical environment drives the overall requirements that must be respected when designing the computing system. Here, reliability is a core aspect where some of the most pressing design challenges are: • monitoring failures throughout the computing system, • determining the impact of failures on the application constraints, and • ensuring correctness of the computing system with respect to application-driven requirements rooted in the physical environment. This paper provides an overview of techniques discussed in the special session to tackle these challenges throughout the stack of layers of the computing system while tightly coupling the design methodology to the physical requirements.</p

Overexpression of an Incw2 gene in endosperm improved yield-related traits in maize

High yield is an eternal goal for crop breeding. Incw2 protein is the enzyme in the metabolic pathway that mobilizes photoassimilated sucrose into numerous reactions of the developing plant seeds, associated with grain yield. In the research, an Incw2 gene driven by 27 kD zein promoter was specifically over-expressed in the endosperm cells of maize inbred line 18-599R by Agrobacterium-mediated genetic transformation. PCR assay displayed that ten of the regenerated plants were integrated with the target gene. By semi-quantitative RT-PCR and invertase activity analysis, five of them showed significantly higher expression of Incw2 transcripts and enzyme activity compared to the wild type. Among them, line 1 stood out because it possessed the highest level of Incw2 mRNA and enzyme activity. The effects of Incw2 over-expression were reflected in the increased chlorophyll content, improved pho¬tosynthesis and delay of leaf senility. In addition, yield-related traits such as ear length, ear diameter, ear weight, grain weight per ear, and hundred-kernel weight appeared to be improved in three of the transformants compared with the wild type. The grain weight per plant of line1 was increased by nearly 10%. The results collectively indicate that it is potentially practical to enhance kernel yield of maize by overexpression of Incw2 in endosperm

Trichostatin A Selectively Suppresses the Cold-Induced Transcription of the ZmDREB1 Gene in Maize

Post-translational modifications of histone proteins play a crucial role in responding to environmental stresses. Histone deacetylases (HDACs) catalyze the removal of an acetyl group from histones and are generally believed to be a transcriptional repressor. In this paper, we report that cold treatment highly induces the up-regulation of HDACs, leading to global deacetylation of histones H3 and H4. Treatment of maize with the HDAC inhibitor trichostatin A (TSA) under cold stress conditions strongly inhibits induction of the maize cold-responsive genes ZmDREB1 and ZmCOR413. However, up-regulation of the ZmICE1 gene in response to cold stress is less affected. The expression of drought and salt induced genes, ZmDBF1 and rab17, is almost unaffected by TSA treatment. Thus, these observations show that HDACs may selectively activate transcription. The time course of TSA effects on the expression of ZmDREB1 and ZmCOR413 genes indicates that HDACs appear to directly activate the ZmDREB1 gene, which in turn modulates ZmCOR413 expression. After cold treatment, histone hyperacetylation and DNA demethylation occurs in the ICE1 binding region, accompanied by an increase in accessibility to micrococcal nuclease (MNase). The two regions adjacent to the ICE1 binding site remain hypoacetylated and methylated. However, during cold acclimation, TSA treatment increases the acetylation status and accessibility of MNase and decreases DNA methylation at these two regions. However, TSA treatment does not affect histone hyperacetylation and DNA methylation levels at the ICE1 binding regions of the ZmDREB1 gene. Altogether, our findings indicate that HDACs positively regulate the expression of the cold-induced ZmDREB1 gene through histone modification and chromatin conformational changes and that this activation is both gene and site selective

Cloning and characterization of miRNAs from maize seedling roots under low phosphorus stress

MicroRNAs (miRNAs) are a class of small, non-coding regulatory RNAs that regulate gene expression by guiding target mRNA cleavage or translational inhibition in plants and animals. In this study, a small RNA library was constructed to identify conserved miRNAs as well as novel miRNAs in maize seedling roots under low level phosphorus stress. Twelve miRNAs were identified by high throughput sequencing of the library and subsequent analysis, two belong to conserved miRNA families (miRNA399b and miRNA156), and the remaining ten are novel and one of latter is conserved in gramineous species. Based on sequence homology, we predicted 125 potential target genes of these miRNAs and then expression patterns of 7 miRNAs were validated by semi-RT-PCR analysis. MiRNA399b, Zma-miR3, and their target genes (Zmpt1 and Zmpt2) were analyzed by real-time PCR. It is shown that both miRNA399b and Zma-miR3 are induced by low phosphorus stress and regulated by their target genes (Zmpt1 and Zmpt2). Moreover, Zma-miR3, regulated by two maize inorganic phosphate transporters as a newly identified miRNAs, would likely be directly involved in phosphate homeostasis, so was miRNA399b in Arabidopsis and rice. These results indicate that both conserved and maize-specific miRNAs play important roles in stress responses and other physiological processes correlated with phosphate starvation, regulated by their target genes. Identification of these differentially expressed miRNAs will facilitate us to uncover the molecular mechanisms underlying the progression of maize seedling roots development under low level phosphorus stress