Functionalized nickel(II)-iron(II) dithiolates as biomimetic models of [NiFe]-H2ases.

To develop the structural and functional modeling chemistry of [NiFe]-H2ases, a series of new biomimetics for the active site of [NiFe]-H2ases have been prepared by various synthetic methods. Treatment of the mononuclear Ni complex (pnp)NiCl2 (pnp = (Ph2PCH2)2NPh) with (dppv)Fe(CO)2(pdt) (dppv = 1,2-(Ph2P)2C2H2, pdt = 1,3-propanedithiolate) and KPF6 gave the dicarbonyl complex [(pnp)Ni(pdt)Fe(CO)2(dppv)](PF6)2 ([1](PF6)2). Further treatment of [1](PF6)2 and [(dppe)Ni(pdt)Fe(CO)2(dppv)](BF4)2 (dppe = 1,2-(Ph2P)2C2H4) with the decarbonylation agent Me3NO and pyridine afforded the novel sp3 C-Fe bond-containing complexes [(pnp)Ni(SCH2CH2CHS)Fe(CO)(dppv)]PF6 ([2]PF6) and [(dppe)Ni(SCH2CH2CHS)Fe(CO)(dppv)]BF4 ([3]BF4). More interestingly, the first t-carboxylato complexes [(pnp)Ni(pdt)Fe(CO)(t-O2CR)(dppv)]PF6 ([4]PF6, R = H; [5]PF6, R = Me; [6]PF6, R = Ph) could be prepared by reactions of [1]PF6 with the corresponding carboxylic acids RCO2H in the presence of Me3NO, whereas further reactions of [4]PF6-[6]PF6 with aqueous HPF6 and 1.5 MPa H2 gave rise to the µ-hydride complex [(pnp)Ni(pdt)Fe(CO)(µ-H)(dppv)]PF6 ([7]PF6). Except for H2 activation by t-carboxylato complexes [4]PF6-[6]PF6 to give a µ-hydride complex ([7]PF6), the sp3 C-Fe bond-containing complex [2]PF6 was found to be a catalyst for proton reduction to H2 under CV conditions. Furthermore, the chemical reactivity of the µ-hydride complex [7]PF6 displayed in the e- transfer reaction with FcPF6 in the presence of CO, the H2 evolution reaction with the protonic acid HCl, and the H- transfer reaction with N-methylacridinium hexafluorophosphate ([NMA]PF6) was systematically studied. As a result, a series of the expected products such as H2, ferrocene, the dicarbonyl complex [1](PF6)2, the µ-chloro complex [(pnp)Ni(pdt)Fe(CO)(µ-Cl)(dppv)]PF6 ([8]PF6), the t-MeCN-coordinated complex [(pnp)Ni(pdt)Fe(CO)(t-MeCN)(dppv)](PF6)2 ([9](PF6)2) and the H- transfer product AcrH2 were produced. While all the newly prepared model complexes were structurally characterized by spectroscopic methods, the molecular structures of some of their representatives were confirmed by X-ray crystallography.

High-Altitude Exposure and Time Interval Perception of Chinese Migrants in Tibet.

High-altitude exposure can negatively impact one's ability to accurately perceive time. This study focuses on Chinese migrants who have traveled to the Tibetan plateau and explores the effects of high-altitude exposure on their time interval judgment abilities based on three separate studies. In Study 1, it was found that exposure to high altitudes negatively impacted the time interval judgment functions of the migrants compared with a low-altitude control group; they exhibited a prolonged response time (540 ms: p = 0.006, 95% CI (−1.70 −0.32)) and reduced accuracy (1080 ms: p = 0.032, 95% CI (0.06 1.26)) in certain behavioral tasks. In Study 2, the results showed that high-altitude exposure and sleepiness had an interactive effect on time interval judgment (1080 ms) (p < 0.05, 95% CI (−0.83 −0.40)). To further verify our interaction hypothesis, in Study 3, we investigated the time interval judgment of interactions between acute high-altitude exposure and sleepiness level. The results revealed that the adaptation effect disappeared and sleepiness significantly exacerbated the negative effects of high-altitude exposure on time interval judgment (p < 0.001, 95% CI (−0.85 −0.34)). This study is the first to examine the effects of high-altitude exposure on time interval judgment processing functions and the effects of sleep-related factors on individual time interval judgment.

Chilling injury mechanism of hardy kiwifruit (Actinidia arguta) was revealed by proteome of label-free techniques.

Refrigeration is an important method to extend shelf life of hardy kiwifruit. However, the inappropriate storage temperature can lead to chilling injury in the fruit. We found that firmness, total soluble solids, and total polyphenolic content of the fruit exposed to 0℃ environment were apparently lower, and titratable acidity content, browning rate, weight loss rate, electrolyte leakage, proline content, and malondialdehyde content were higher obviously than 4℃. A total of 244 differentially expressed proteins were found result from differential temperatures, among which 113 were up-regulated and 131 were down-regulated. Subcellular localization results presented that the differentially expressed proteins which were affected by low temperature were located in cytoplasmic, chloroplast, nuclear, mitochondrial, plasma membrane, and extracellular. Kyoto Encyclopedia of Genes and Genomes analysis showed that the differentially expressed proteins were mainly participated in synthesis of citrate cycle, oxidative phosphorylation, fatty acid biosynthesis, and starch and sucrose metabolism. Protein-protein interaction results revealed that central proteins interaction points respectively are 30S ribosomal proteins, 30S ribosomal protein S7, chloroplastic, cell division cycle 5-like protein, 50S ribosomal protein, ribosomal protein, ribosomal protein L6 protein, and SRP54 subunit protein. The quality deviations of all identified peptides were mainly distributed within 10 ppm, and MS2 has an ideal andromeda score, with more than 87.82% peptide scores above 60 points, and the median peptide score of 99.28 points. Therefore, the results of this study provide important information for new gene revelation and gene interaction relationship in hardy kiwifruit of chilling injury. PRACTICAL APPLICATIONS: Inhibition of cold damage in hardy kiwifruit under low temperature is very important work for the development of its storage industry. However, many qualities of fruit will deteriorate after long-term cold storage and those biological activities of the fruits are regulated by proteins. It is, therefore, of great significance to reveal the key proteins caused cold damage in hardy kiwifruit. Moreover, the study results could provide a scientific information for the quality improvement and genetic modification of hardy kiwifruit.

[Effect of single hyperbaric oxygen treatment on attention networks in young migrants in Tibet].

Many studies have shown that high-altitude exposure could significantly influence human cognition, and the approaches which could enhance the human cognition in high-altitude hypoxia environment attract great attention. In the present study, we recruited a total of 60 subjects who had been migrated to Tibet University as adults for more than one year. These participants were randomly divided into the experimental group and the control group. The participants in the experimental group were instructed to complete a hyperbaric oxygen treatment, and those in the control group just completed a wait condition. By using the attention network test (ANT), the changes of the attention function before and after a single session of hyperbaric oxygen treatment were explored. The results showed that single hyperbaric oxygen treatment significantly improved the orienting function of attention, with an obvious post-intervention effect, but not the alerting and conflict function of attention. We also found a strong association between alerting function and conflict function after the end of intervention, suggesting the change of the overall performance of attention function. The present findings might suggest that the improvement of attention function by a single session of hyperbaric oxygen intervention is derived from the increase of general cognitive resources, rather than the transfer of cognitive resources within the attention system.

Effects of age on the peak ratio of ophthalmic artery Doppler.

ABSTRACT: This study aimed to investigate the effects of age on the peak ratio (PR) of ophthalmic artery (OA) Doppler.The initial peak velocity (P1), second peak velocity (P2) and PR of OA were detected by color Doppler ultrasonography in 147 healthy subjects. All of the subjects were divided into 6 groups (G1-G6) according to the age. (G1, 20-29 years; G2, 30-39 years; G3, 40-49 years; G4, 50-59 years; G5, 60-69 years; and G6, 70 years or older). The blood pressure and heart rate were also examined before ultrasonography. The influences of age, blood pressure and heart rate on the P1, P2, and PR were further evaluated.There were significant differences in the P2 and PR among different age groups except for P1. There were no significant differences in the P2 and PR between the first 2 groups, neither among the latter 4 groups. Nevertheless, P2 and PR in the first 2 groups were significantly different from those in the latter 4 groups. In addition, both P2 and PR (not P1) increased significantly with age, systolic and diastolic blood pressure. P1, P2 and PR were not related to heart rate. Both P2 and PR were closely related to the age. PR also had a weak relationship with systolic blood pressure.Both P2 and PR of OA Doppler increase with age. Concern should be raised when P2 and PR are used to evaluate the hemodynamic change of OA.

Nickel-Iron Dithiolato Hydrides Derived from H2 Activation by Their µ-Hydroxo Ligand-Containing Analogues.

Here, we describe the synthesis and characterization of the two µ-hydrido models of [NiFe]H2ases prepared from a new type of H2 activation by the corresponding two µ-hydroxo models. In addition, another µ-hydrido model prepared by the anionic exchange between one of the two µ-hydrido models and KPF6 is also reported. Interestingly, the synthesis of the two µ-hydrido models from H2 activation represents the first functional modeling of the H2 activation catalyzed by the [NiFe]H2ase (Ni-SIr)I state to give the Ni-R state.

Dithiolato-bridged nickel-iron complexes as models for the active site of [NiFe]-hydrogenases.

The structural and functional modeling of the active site of [NiFe]-hydrogenases has been proved to be challenging to a great extent. Herein, we report the synthesis, structures, and some properties of the NiFe-based dicarbonyl, terminal hydride, and µ-hydroxo models for the active site of [NiFe]-hydrogenases.

High-frequency sonographic measurements of true and false vocal cords.

OBJECTIVE: The purpose of this study was to prospectively identify the normal sonographic values of human true and false vocal cords. METHODS: In total, 229 healthy volunteers were divided into 8 groups according to their age and sex. High-frequency sonography was used to measure the length, width, and thickness of both true and false vocal cords. Measurements were compared between groups, and correlations with age were analyzed. Forty of the 229 volunteers also participated in reliability and reproducibility studies. RESULTS: The sonographic measurements had good reproducibility, with intraclass correlation coefficient ranges of 0.736 to 0.903 for interobserver reliability and 0.723 to 0.943 for intraobserver reliability. Measurements for the 3 parameters of both true and false vocal cords in male adults were greater than those in female adults (P < .001). The length, width, and thickness of true and false vocal cords in participants younger than 18 years were obviously correlated with age (r = 0.835-0.957; P < .001), but no significant correlation was found in the adult groups. The rates of visualization in male groups were significantly lower than those in female groups (P < .001) and gradually decreased with increasing age. CONCLUSIONS: Both true and false vocal cords can be shown by high-frequency sonography, which can quantitatively measure both true and false vocal cords with good reliability and reproducibility.