Pivotal Role of Geometry Regulation on O-O Bond Formation Mechanism of Bimetallic Water Oxidation Catalysts.

In this study, we highlight the impact of catalyst geometry on the formation of O-O bonds in Cu2 and Fe2 catalysts. A series of Cu2 complexes with diverse linkers are designed as electrocatalysts for water oxidation. Interestingly, the catalytic performance of these Cu2 complexes is enhanced as their molecular skeletons become more rigid, which contrasts with the behavior observed in our previous investigation with Fe2 analogs. Moreover, mechanistic studies reveal that the reactivity of the bridging O atom results in distinct pathways for O-O bond formation in Cu2 and Fe2 catalysts. In Cu2 systems, the coupling takes place between a terminal CuIII -OH and a bridging µ-O⋅ radical. Whereas in Fe2 systems, it involves the coupling of two terminal Fe-oxo entities. Furthermore, an in-depth structure-activity analysis uncovers the spatial geometric prerequisites for the coupling of the terminal OH with the bridging µ-O⋅ radical, ultimately leading to the O-O bond formation. Overall, this study emphasizes the critical role of precisely adjusting the spatial geometry of catalysts to align with the O-O bonding pathway.

Iron-Catalyzed Water Oxidation: O-O Bond Formation via Intramolecular Oxo-Oxo Interaction.

Herein, we report the importance of structure regulation on the O-O bond formation process in binuclear iron catalysts. Three complexes, [Fe2 (µ-O)(OH2 )2 (TPA)2 ]4+ (1), [Fe2 (µ-O)(OH2 )2 (6-HPA)]4+ (2) and [Fe2 (µ-O)(OH2 )2 (BPMAN)]4+ (3), have been designed as electrocatalysts for water oxidation in 0.1 M NaHCO3 solution (pH 8.4). We found that 1 and 2 are molecular catalysts and that O-O bond formation proceeds via oxo-oxo coupling rather than by the water nucleophilic attack (WNA) pathway. In contrast, complex 3 displays negligible catalytic activity. DFT calculations suggested that the anti to syn isomerization of the two high-valent Fe=O moieties in these catalysts takes place via the axial rotation of one Fe=O unit around the Fe-O-Fe center. This is followed by the O-O bond formation via an oxo-oxo coupling pathway at the FeIV FeIV state or via oxo-oxyl coupling pathway at the FeIV FeV state. Importantly, the rigid BPMAN ligand in complex 3 limits the anti to syn isomerization and axial rotation of the Fe=O moiety, which accounts for the negligible catalytic activity.

Effects of simulated drought stress on carotenoid contents and expression of related genes in carrot taproots.

Carotenoids are liposoluble pigments found in plant chromoplasts that are responsible for the yellow, orange, and red colors of carrot taproots. Drought is one of the main stress factors affecting carrot growth. Carotenoids play important roles in drought resistance in higher plants. In the present work, the carotenoid contents in three different-colored carrot cultivars, 'Kurodagosun' (orange), 'Benhongjinshi' (red), and 'Qitouhuang' (yellow), were determined by ultra-high-performance liquid chromatography (UPLC) after 15% polyethylene glycol (PEG) 6000 treatment. Real-time fluorescence quantitative PCR (RT-qPCR) was then used to determine the expression levels of carotenoid synthesis- and degradation-related genes. Increases in ß-carotene content in 'Qitouhuang' taproots under drought stress were found to be related to the expression levels of DcPSY2 and DcLCYB. Increases in lutein and decreases in α-carotene content in 'Qitouhuang' and 'Kurodagosun' under PEG treatment may be related to the expression levels of DcCYP97A3, DcCHXE, and DcCHXB1. The expression levels of DcNCED1 and DcNCED2 in the three cultivars significantly increased, thus suggesting that NCED genes could respond to drought stress. Analysis of the growth status and carotenoid contents of carrots under PEG treatment indicated that the orange cultivar 'Kurodagosun' has better adaptability to drought stress than the other cultivars and that ß-carotene and lutein may be involved in the stress resistance process of carrot.

Sequencing, assembly, annotation, and gene expression: novel insights into browning-resistant Luffa cylindrica.

Luffa is a kind of melon crop widely cultivated in temperate regions worldwide. Browning is one of the serious factors affecting the quality of Luffa. Therefore, the molecular mechanism of Luffa browning is of great significance to study. However, the molecular diversity of Luffa cultivars with different browning-resistant abilities has not been well elucidated. In our study, we used high-throughput sequencing to determine the transcriptome of two Luffa cylindrica cultivars '2D-2' and '35D-7'. A total of 115,099 unigenes were clustered, of which 22,607 were differentially expression genes (DEGs). Of these DEGs, 65 encoding polyphenol oxidase, peroxidase, or ascorbate peroxidase were further analyzed. The quantitative real-time PCR (RT-qPCR) data indicated that the expression levels of the LcPPO gene (Accession No.: Cluster-21832.13892) was significantly higher in '35D-7' compared with that in '2D-2'. Several POD genes (Accession No.: Cluster-21832.19847, Cluster-21832.30619 and Cluster-48491.2) were also upregulated. Analysis of the plantTFDB database indicated that some transcription factors such as WRKY gene family may also participate in the regulation of Luffa browning. The results indicated that the divergence of genes expression related to enzymatic reaction may lead to the different browning resistances of Luffa. Our study will provide a theoretical basis for breeding of browning-resistant Luffa.

AgNAC1, a celery transcription factor, related to regulation on lignin biosynthesis and salt tolerance.

The NAC transcription factor participates in various biotic and abiotic stress responses and plays a critical role in plant development. Lignin is a water-insoluble dietary fiber, but it is second only to cellulose in abundance. Celery is the main source of dietary fiber, but its quality and production are limited by various abiotic stresses. Here, AgNAC1 containing the NAM domain was identified from celery. AgNAC1 was found to be a nuclear protein. Transgenic Arabidopsis thaliana plants hosting AgNAC1 have longer root lengths and stomatal axis lengths than the wide type (WT). The evidence from lignin determination and expression levels of lignin-related genes indicated that AgNAC1 plays a vital role in lignin biosynthesis. Furthermore, the results of the physiological characterization and the drought and salt treatments indicate that AgNAC1-overexpressing plants are significantly resistive to salt stress. Under drought and salt treatments, the AgNAC1 transgenic Arabidopsis thaliana plants presented increased superoxide dismutase (SOD) and peroxidase (POD) activities and decreased malondialdehyde (MDA) content and size of stomatal apertures relatively to the WT plants. The AgNAC1 served as a positive regulator in inducing the expression of stress-responsive genes. Overall, the overexpressing AgNAC1 enhanced the plants' resistance to salt stress and played a regulatory role in lignin accumulation.

Influence of Adding Chinese Yam (Dioscorea opposita Thunb.) Flour on Dough Rheology, Gluten Structure, Baking Performance, and Antioxidant Properties of Bread.

Impacts of wheat flour substituted with various levels of Chinese yam (Dioscorea opposita Thunb.) flour (from 0% to 25%) on the dough rheological characteristics, gluten structure, baking performance, and antioxidant properties of bread were investigated. The water absorption increased significantly (p < 0.05), while development time and stability decreased remarkably (p < 0.05) as the proportion of yam flour increased. SEM results indicated that the addition of yam flour destroyed the gluten network structure in the dough. Fourier Transform Infrared Spectroscopy (FTIR) spectra showed that addition of yam flour decreased the content of α-helix and ß-sheet in gluten. With the increase in the proportion of yam flour, the specific volume and overall acceptability decreased (p < 0.05) whereas the total phenolics content (TPC), polysaccharides content, total flavonoids content (TFC), allantoin content, The 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging capability, fractal dimension, and hardness increased (p < 0.05). Overall, breads made of wheat flour replacement with no more than 15% Guihuai number 2 yam flour were of a high quality and had more antioxidant properties. These showed that Guihuai number 2 had broad application prospects in baked products.

Electrocatalytic Water Oxidation by an Unsymmetrical Di-Copper Complex.

An unsymmetrical di-copper complex, ([Cu2(TPMAN)(µ-OH)(H2O)]3+, was prepared and used for electrocatalytic water oxidation in neutral conditions. This complex is a stable and efficient homogeneous catalyst during the electrocatalytic oxygen evolution process ( kcat = 0.78 s-1) with 780 mV onset overpotential in 0.1 M phosphate buffer (pH 7.0). The water oxidation mechanism of the unsymmetrical catalyst [Cu2(TPMAN)(µ-OH)]3+ exhibits different behaviors than that of [Cu2(BPMAN)(µ-OH)]3+, such as two redox steps with different pH dependences, a significant kinetic isotope effect, and buffer concentration dependence. All these changes were ascribed to the open site on the Cu center that is formed by removal of the hemilabile pyridyl site, which acts as an intramolecular proton acceptor to assist the O-O bond formation step.

Bimetallic cooperative effect on O-O bond formation: copper polypyridyl complexes as water oxidation catalyst.

The performance of water oxidation catalysis by a Cu-based polypyridyl complex, [CuII(TPA)(OH2)]2+ (1H; TPA = tris-(pyridylmethyl)amine), has been investigated in neutral aqueous solution by electrochemical methods. Compared with our previously reported binuclear catalyst, [(BPMAN)(CuII)2(µ-OH)]3+ (2; BPMAN = 2,7-[bis(2-pyridylmethyl)aminomethyl]-1,8-naphthyridine), mononuclear catalyst 1 has a higher overpotential and lower catalytic activity toward water oxidation under the same conditions. Experimental results revealed that the O-O bond formation occurred via a water nucleophilic attack mechanism in which formal CuIV(O) is proposed as a key intermediate for the mononuclear catalyst 1H. In contrast, for the binuclear catalyst, O-O bond formation was facilitated by bimetallic cooperation between the two CuIII centers.

Redox-Active Ligand Assisted Multielectron Catalysis: A Case of CoIII Complex as Water Oxidation Catalyst.

Water oxidation is the key step in both natural and artificial photosynthesis to capture solar energy for fuel production. The design of highly efficient and stable molecular catalysts for water oxidation based on nonprecious metals is still a great challenge. In this article, the electrocatalytic oxidation of water by Na[(L4-)CoIII], where L is a substituted tetraamido macrocyclic ligand, was investigated in aqueous solution (pH 7.0). We found that Na[(L4-)CoIII] is a stable and efficient homogeneous catalyst for electrocatalytic water oxidation with 380 mV onset overpotential in 0.1 M phosphate buffer (pH 7.0). Both ligand- and metal-centered redox features are involved in the catalytic cycle. In this cycle, Na[(L4-)CoIII] was first oxidized to [(L2-)CoIIIOH] via a ligand-centered proton-coupled electron transfer process in the presence of water. After further losing an electron and a proton, the resting state, [(L2-)CoIIIOH], was converted to [(L2-)CoIV═O]. Density functional theory (DFT) calculations at the B3LYP-D3(BJ)/6-311++G(2df,2p)//B3LYP/6-31+G(d,p) level of theory confirmed the proposed catalytic cycle. According to both experimental and DFT results, phosphate-assisted water nucleophilic attack to [(L2-)CoIV═O] played a key role in O-O bond formation.

Clinical features of benign epilepsy of childhood with centrotemporal spikes in chinese children.

This multicenter clinical trial was conducted to examine current practice of benign epilepsy with centrotemporal spikes and especially address the question that in what circumstances 1 antiepileptic drug (AED) should be preferred.Twenty-five medical centers participate in this clinical trial. The general information, clinical information, and treatment status were collected under the guidance of clinicians and then analyzed. Difference between different treatment groups was compared, and usefulness of the most commonly used AEDs was evaluated.A total of 1817 subjects were collected. The average age of the subject was 8.81 years. The average age of onset is 6.85 years (1-14 years). Male-to-female ratio is 1.13:1. A total of 62.9% of the patients are receiving monotherapies, and 10.6% are receiving multidrug therapy. Both age and course of disease of treated rolandic epilepsy (RE) patients are significantly different from those of untreated patients. Bilateral findings on electroencephalography (EEG) are less seen in patients with monotherapy compared with patients with multidrug therapy. Except for 25.4% patients not taking any AEDs, oxcarbazepine (OXC), sodium valproate (VPA), and levetiracetam (LEV) are the most commonly used 3 AEDs. VPA and LEV are commonly used in add-on therapy. OXC and LEV are more effective as monotherapy than VPA.Age of onset of Chinese RE patients is 6.85 years. Bilateral findings on EEG could be a risk factor to require multidrug therapy. In Chinese patients, OXC, VPA, and LEV are most commonly used AEDs as monotherapy and OXC and LEV are more effective than VPA.

Electrocatalytic water oxidation by a dinuclear copper complex in a neutral aqueous solution.

Electrocatalytic water oxidation using the oxidatively robust 2,7-[bis(2-pyridylmethyl)aminomethyl]-1,8-naphthyridine ligand (BPMAN)-based dinuclear copper(II) complex, [Cu2(BPMAN)(µ-OH)](3+), has been investigated. This catalyst exhibits high reactivity and stability towards water oxidation in neutral aqueous solutions. DFT calculations suggest that the O-O bond formation takes place by an intramolecular direct coupling mechanism rather than by a nucleophilic attack of water on the high-oxidation-state Cu(IV)=O moiety.

FOXD1 promotes breast cancer proliferation and chemotherapeutic drug resistance by targeting p27.

Forkhead transcription factors are essential for diverse processes in early embryonic development and organogenesis. As a member of the forkhead family, FOXD1 is required during kidney development and its inactivation results in failure of nephron progenitor cells. However, the role of FOXD1 in carcinogenesis and progression is still limited. Here, we reported that FOXD1 is a potential oncogene in breast cancer. We found that FOXD1 is up-regulated in breast cancer tissues. Depletion of FOXD1 expression decreases the ability of cell proliferation and chemoresistance in MDA-MB-231 cells, whereas overexpression of FOXD1 increases the ability of cell proliferation and chemoresistance in MCF-7 cells. Furthermore, we observed that FOXD1 induces G1 to S phase transition by targeting p27 expression. Our results suggest that FOXD1 may be a potential therapy target for patients with breast cancer.

[Application of Narcotrend-assisted anesthesia in-depth monitor during escharectomy and skin transplantation in burn patients with target-controlled infusion of remifentanil hydrochloride and propofol].

OBJECTIVE: To evaluate the feasibility and efficacy of Narcotrend (NT) monitor in monitoring the depth of anesthesia in severely burned patients with target-controlled infusion (TCI) of remifentanil hydrochloride and propofol during perioperative period. METHODS: Eighty patients with severe burn hospitalized from February to November 2011, to whom eschar excision was performed within one week after injury, were enrolled. They were classified into II to III grade according to the American Society of Anesthetists classification, and their total burn area ranged from 31% to 50%TBSA, or full-thickness burn area from 11% to 20% TBSA. Patients were divided into trial group (monitoring depth of anesthesia with routine method and NT monitor) and control group (monitoring depth of anesthesia with routine method) according to the random number table, with 40 cases in each group. All patients received TCI of remifentanil hydrochloride and propofol to induce and maintain anesthesia. During the operation, the anesthesia level of NT monitor used in the trial group was maintained from grade D1 to E0, while the fluctuation of mean arterial pressure (MAP) and heart rate of patients in control group was maintained around the basic values within a range of 20%, and on the basis of which, concentrations of two narcotics were adjusted. Concentrations of remifentanil hydrochloride and propofol during maintenance of anesthesia were recorded. The duration from drug withdrawal to waking from anesthesia (including the duration from drug withdrawal to eye opening by calling and the duration from drug withdrawal to orientation recovery) of patients was recorded. Values of MAP and heart rate at admission into the operation room, loss of consciousness, 2 min after intubation, before operation, 2, 15, and 30 min after the beginning of operation, and the end of operation were recorded. The prediction probability (P(k)) of NT stage (NTS) and NT index (NTI) in trial group, and that of MAP and heart rate in control group for two durations from drug withdrawal to waking form anesthesia were recorded. The administration of vasoactive drugs and intraoperative awareness of patients in two groups were recorded. Data were processed with t test, analysis of variance, and chi-square test, and the relationship between NTS, NTI, MAP, heart rate and their corresponding P(k) for the duration from drug withdrawal to orientation recovery was processed with Spearman correlation analysis. RESULTS: Maintained target effect-site concentration of remifentanil hydrochloride and target plasma concentration of propofol of patients were obviously lower in trial group [(2.62 ± 0.35) ng/mL, (3.84 ± 0.22) µg/mL] than in control group [(2.95 ± 0.21) ng/mL, (4.16 ± 0.31) µg/mL, with t values respectively -5.113 and -5.324, P values all below 0.01]. The duration from drug withdrawal to eye opening by calling and the duration from drug withdrawal to orientation recovery were obviously shorter in trial group [(10.2 ± 0.7) min, (11.1 ± 1.0) min] than in control group [(11.3 ± 1.0) min, (13.1 ± 0.7) min, with t values respectively -5.740 and -10.806, P values all below 0.01]. The MAP (except for 2 min after intubation) and the heart rate of patients in both groups were lower at the time points from loss of consciousness to the end of operation than at the time of entering operation room (with F values respectively 12.074, 36.425, P values all below 0.01 in trial group and F values respectively 21.776, 35.759, P values all below 0.01 in control group). The statistically significant difference between two groups in MAP level was only observed at the time of loss of consciousness (t = 3.985, P < 0.01). MAP level was close in two groups at other time points. Heart rates of patients in two groups were close during perioperative period. P(k) values of NTS and NTI for the duration from drug withdrawal to eye opening by calling (0.937 ± 0.025, 0.899 ± 0.049) were obviously higher than those of MAP and heart rate for this duration (0.579 ± 0.057, 0.536 ± 0.039, F = 900.337, P < 0.01). P(k) values of NTS and NTI for the duration from drug withdrawal to the orientation recovery (0.901 ± 0.031, 0.868 ± 0.046) were significantly higher than those of MAP and heart rate for this duration (0.532 ± 0.060, 0.483 ± 0.044, F = 890.895, P < 0.01). NTS, NTI, MAP, and heart rate were respectively negative, positive, positive and positive in correlation with their P(k) values for the duration from drug withdrawal to the orientation recovery (with r values from -0.734 to 0.682, P values all below 0.01). There was no statistically significant difference between two groups in administration of vasoactive drugs. No intraoperative awareness occurred. CONCLUSIONS: Application of Narcotrend monitor in monitoring the depth of anesthesia in severely burned patients during perioperative period with TCI of remifentanil hydrochloride and propofol is beneficial to reducing dosage of narcotics and shortening duration of recovery from anesthesia, and it can accurately predict the level of consciousness of patients at the time of withdrawal of anesthesia.

Effect of zibu shenjing fang (see text) on growth and development of the mouse with kidney-essence insufficiency and study on the mechanism.

OBJECTIVE: To investigate effects of Zibu Shenjing Fang (see text) on growth and development of the mouse with insufficiency ofkidney-essence and the mechanism. METHODS: Total 50 mice were randomly divided into a normal group, a model group, a Jingui Shenqi Wan (see text) group, a Zibu Shenjing Fang high dose group and a Zibu Shenjing Fang low dose group, 10 mice in each group. The kidney-essence insufficiency mouse model was established by use of threat-injuring the kidney combined with over-fatigue. At the same time of modeling, the mice in the model group were intragastrically administrated with saline 20 mL x kg(-1) x d(-1), in the Jingui Shenqi Wan group with suspension of the Jingui Shenqi Wan 2.7 g x kg(-1) x d(-1), in the Zibu Shenjing Fang high dose group with Zibu Shenjing Fang 20 g x kg(-1) x d(-1) and in the Zibu Shenjing Fang low dose group with Zibu Shenjing Fang 10 g x kg(-1) x d(-1), for 21 consecutive days. The general state was observed, the body weight was weighted, and serum growth hormone (GH) and insulin-like growth factor-1 (IGF-1) contents were detected. RESULTS: Compared with model group, Zibu Shenjing Fang groups and Jingui Shenqi Wan group could improve manifestation of the mouse with kidney-essence insufficiency, increase body weight of the mouse and serum GH and IGF-1 contents, especially in the high dose group. CONCLUSION: Zibu Shenjing Fang gives play to the function of tonifying the kidney and replenishing essence through regulating GH and IGF-1 levels, so as to influence growth and development of the mouse.