Ab Initio Metadynamics Simulations of Hexafluoroisopropanol Solvent Effects: Synergistic Role of Solvent H-Bonding Networks and Solvent-Solute C-H/π Interactions.

The solvent effects in Friedel-Crafts cycloalkylation of epoxides and Cope rearrangement of aldimines were investigated by using ab initio molecular dynamics simulations. Explicit molecular treatments were applied for both reactants and solvents. The reaction mechanisms were elucidated via free energy calculations based on metadynamics simulations. The results reveal that both reactions proceed in a concerted fashion. Key solvent-substrate interactions are identified from the structures of transition states with explicit solvent molecules. The remarkable promotion effect of hexafluoroisopropanol solvent is ascribed to the synergistic effect of H-bonding networks and C-H/π interactions with substrates.

How hexafluoroisopropanol solvent promotes Diels-Alder cycloadditions: ab initio metadynamics simulations.

The solvent effects in Diels-Alder cycloadditions were studied by using ab initio molecular dynamics simulations with explicit molecular treatments for both substrates and solvents. Energy decomposition analysis was used to investigate the role of H-bonding networks of hexafluoroisopropanol solvent in promoting both reactivity and regioselectivity.

Association of Met/Val polymorphism of BDNF gene with Alzheimer's disease in Chinese patients.

Alzheimer's is the most common cause of dementia in the elderly. In this disease, genetic and environmental factors are involved. In Alzheimer's, changes of nucleotide 196 (G> A) or valine polymorphism of 66-methionine in the BDNF gene is a risk factor for brain-derived neurogenic factors. In China, this polymorphism has not been studied in Alzheimer's patients and perhaps this study could provide appropriate information on the prognosis and susceptibility of the disease. Therefore, in this case-control study, 73 patients with Alzheimer's disease and 100 patients as a healthy control group were studied. Blood samples were taken from the mentioned individuals and DNA was extracted. After quantitative and qualitative DNA analysis, a PCR-RFLP test was performed and the results of both groups were compared. The results showed that 14 patients and 7 people in the control group had BDNF gene polymorphism. In the patient group, the number of people with normal allele was 59. Heterozygous people were 8 and people with methionine/methionine alleles were 6. In the control group, 93 normal individuals, 5 heterozygous individuals, and 2 people had methionine/methionine alleles. In general, increasing the accumulation of valine/methionine polymorphism of the BDNF gene in Alzheimer's patients compared to control can indicate the role of this polymorphism. Clinically, patients with this polymorphism had a more unfavorable clinical condition compared to patients without it. Therefore, evaluation of the presence of this polymorphism can provide appropriate information about the disease status.

Experiment on monitoring leakage of landfill leachate by parallel potentiometric monitoring method.

The accumulation of municipal solid waste (MSW) in landfills often becomes a serious pollution source of geological environment and groundwater. The geological environment is the carrier of the landfill, and also the main pollution object of the landfill. The main pollution modes of the landfill site to the surrounding geological environment are purging, flushing, leachate, etc. If the leachate leakage cannot be found and repaired in time, it will cause serious harm to the geological environment and groundwater. The cost of geological environment and groundwater sampling through borehole surveys is high. Therefore, monitoring the seepage path and migration law of leachate is of great significance for determining the pollution range of the landfill site. In this study, by adjusting the grids of different sizes and changing the flow rate of leachate, the monitoring of fluid migration of different types of leachate was strengthened. The results show that the parallel potential monitoring method can quickly reflect the location and number of leachate points and the migration law of leachate. It provides effective reference data for landfill leachate monitoring.

Multi-factor settlement prediction around foundation pit based on SSA-gradient descent model.

With the rise of machine learning, a lot of excellent algorithms are used for settlement prediction. Backpropagation (BP) and Elman are two typical algorithms based on gradient descent, but their performance is greatly affected by the random selection of initial weights and thresholds, so this paper chooses Sparrow Search Algorithm (SSA) to build joint model. Then, two sets of land subsidence monitoring data generated during the excavation of a foundation pit in South China are used for analysis and verification. The results show that the optimization effect of SSA on the gradient descent model is remarkable and the stability of the model is improved to a certain extent. After that, SSA is compared with GA and PSO algorithms, and the comparison shows that SSA has higher optimization efficiency. Finally, select SSA-KELM, SSA-LSSVM and SSA-BP for further comparison and it proves that the optimization efficiency of SSA for BP is higher than other kind of neural network. At the same time, it also shows that the seven influencing factors selected in this paper are feasible as the input variables of the model, which is consistent with the conclusion drawn by the grey relational analysis.

Transcriptome Analysis of Near-Isogenic Lines Provides Novel Insights into Genes Associated with Seed Low-Temperature Germination Ability in Maize (Zea mays L.).

Maize originated from tropical regions and is extremely sensitive to low temperature during germination. Our previous work identified a major QTL, qp1ER1-1, for low temperature germination ability (LTGA) of maize. Here, we introgressed qp1ER1-1 from the tolerant line L220 into the sensitive line PH4CV to generate two near isogenic lines NIL220-3 and NIL220-25. When germinated under cold temperature for 25 days (Cold-25), the NILs showed similar seedling root length and shoot length to L220, but significantly higher than PH4CV. However, when germinated under cold temperature for 15 days (Cold-15) or under normal temperature (25 °C) for 3 days (CK-3), all lines showed similar seedling performance, indicating that introgression of qp1ER1-1 from L220 into PH4CV could improve LTGA of NIL220-3 and NIL220-25. The whole seedlings, including root and shoot, of Cold-15 and CK-3 were harvested for transcriptome analysis, when both stayed at a similar developmental stage. Dry seed embryo was sequenced as a non-germination control (CK-0). Compared with PH4CV, the tolerant line (L220, NIL220-3, and NIL220-25) specifically expressed genes (different expressed genes, DEGs) were identified for CK-0, Cold-15, and CK-3. Then, DEGs identified from Cold-15, but not from CK-0 or CK-3, were defined as tolerant line specifically expressed LTGA genes. Finally, 1786, 174, and 133 DEGs were identified as L220, NIL220-3, and NIL220-25 specifically expressed LTGA genes, respectively. Of them, 27 were common LTGA genes that could be identified from all three tolerant lines, with two (Zm00001d031209 and Zm00001d031292) locating in the confidence interval of qp1ER1-1. In addition, GO analysis revealed that L220 specifically expressed LTGA genes were majorly enriched in the cell division process and plasma membrane related categories. Taken together, these results provided new insight into the molecular mechanism of maize seed LTGA and facilitated the cloning of the qp1ER1-1 gene.

Transcriptome Analysis Identifies Novel Genes Associated with Low-Temperature Seed Germination in Sweet Corn.

Typically, sweet corn, particularly sh2 sweet corn, has low seed vigor owing to its high sugar and low starch content, which is a major problem in sweet corn production, particularly at low temperatures. There is considerable variation in the germination rates among sweet corn varieties under low-temperature conditions, and the underlying mechanisms behind this phenomenon remain unclear. In this study, we screened two inbred sweet corn lines (tolerant line L282 and sensitive line L693) differing in their low-temperature germination rates; while no difference was observed in their germination rates at normal temperatures. To identify the specifically induced genes influencing the germination capacity of sweet corn at low temperatures, a transcriptome analysis of the two lines was conducted at both normal and low temperatures. Compared to the lines at a normal temperature, 3926 and 1404 differently expressed genes (DEGs) were identified from L282 and L693, respectively, under low-temperature conditions. Of them, 830 DEGs were common DEGs (cDEGs) that were identified from both L282 and L693, which were majorly enriched in terms of microtubule-based processes, histone H3-K9 modification, single-organism cellular processes, and carbohydrate metabolic processes. In addition, 3096 special DEGs (sDEGs), with 2199 upregulated and 897 downregulated, were detected in the tolerant line L282, but not in the sensitive line L693. These sDEGs were primarily related to plasma membranes and oxygen-containing compounds. Furthermore, electric conductivity measurements demonstrated that the membrane of L282 experienced less damage, which is consistent with its strong tolerance at low temperatures. These results expand our understanding of the complex mechanisms involved in the cold germination of sweet corn and provide a set of candidate genes for further genetic analysis.

Sensitive Detection of Serum Creatinine Based on ß-Cyclodextrin-Ferrocenylmethanol Modified Screen-printed Electrode.

Ferrocenylmethanol (Fc-OH) is included in ß-cyclodextrin (ß-CD) to form the ß-CD-Fc-OH complex by host-guest supramolecular interaction. ß-CD dissociates from the ß-CD-Fc-OH complex due to the conversion of Fc-OH to Fc+-OH under a stimulus of oxidant. In our study, Fc-OH is oxidized after a series of enzymatic reactions of creatinine, which blocks the other means for oxidation of Fc-OH. And the background noise is reduced for testing for serum creatinine (sCr). The chronoamperometry signal for creatinine (with a constant potential -0.3 V vs. Ag/AgCl) increases linearly in the 1 - 1000 µM range, with a limit of detection as low as 0.5 µM. The amperometric potential of -0.3 V greatly prevents the interference of various redox substances in serum. The biosensor was used to test 120 clinical specimens and the results showed a linear correlation with the biochemical analyzer (R2 = 0.9885). The biosensor could be applied to clinical trials and offers good prospects for clinical sCr detection.

[QTL analysis for percentage of exserted stigma in rice (Oryza sativa L.)].

Percentage of exserted stigmas (PES) was investigated in Hainan by using a population of 127 DH population derived from a cross between a high-PES indica variety Zaiyeqing 8 (ZYQ 8) and a low-PES japonica variety Jingxi 17(JX 17) and its molecular linkage map of 234 markers. Two QTLs (qPES-2, qPES-3) for PES were located on chromosome 2 and 3, respectively. There is no difference between the QTLs for single stigma exsertation and total PES, but the only QTL for dual stigma exsertation located on chromosome 2, whose positive additive effect was from ZYQ 8. Simultaneously the detected QTLs for spikelets per panicle located on chromosome 6,8, respectively and had no linkage relation with the QTLs for PES.