Sheep dung deposition disrupted the soil microbiome in degraded grassland but not in non-degraded grassland.

Grazing is the most extensive land use in grassland worldwide, wherein the soil microbiome is known to support multiple ecosystem functions. Yet, the experimental impact of livestock grazing and dung deposits on the soil microbiome in degraded grassland remains poorly understood. We examined the effects of sheep dung depositions on the bacterial and fungal microbiome of two grasslands: non-degraded and degraded (long-term overgrazing) in northern China. Specifically, sheep dung was experimentally added to the soil and its effects on the soil microbial community were determined 3 months later (corresponding to livestock excreta deposited throughout the entire growing season of grassland, June to September). Our results showed that sheep dung additions showed negative effects on the soil microbiome of already degraded grassland, while with a diminished impact on the non-degraded grassland. In particular, dung deposition decreased soil microbial Shannon index, notably significantly reducing fungal diversity in degraded grassland. Moreover, sheep dung deposition modifies soil bacterial community structure and diminishes bacterial community network complexity. The alteration of soil pH caused by sheep dung deposition partially explains the decline in microbial diversity in degraded grassland. However, sheep dung did not alter the relative abundance and community composition of bacterial and fungal dominant phyla either in the non-degraded or in the degraded grassland. In conclusion, the short-term deposition of sheep dung exerted a detrimental influence on the microbial community in degraded grassland soil. It contributes new experimental evidence regarding the adverse effects of livestock grazing, particularly through dung deposition, on the soil microbiome in degraded grassland. This knowledge is crucial for guiding managers in conserving the soil microbiome in grazed grasslands.

Synergistic Active Heterostructure Design for Enhanced Two Electron Oxygen Reduction via Chemical and Electrochemical Reconstruction of Heterosulfides.

Transition metal sulfides, particularly heterostructures, represent a promising class of electrocatalysts for two electron oxygen reduction (2e- ORR), however, understanding the dynamic structural evolution of these catalysts during alkaline ORR remains relatively unexplored. Herein, NiS2/In2.77S4 heterostructure was synthesized as a precatalyst and through a series of comprehensive ex-situ and in-situ characterizations, including X-ray absorption spectroscopy, Raman spectroscopy, transient photo-induced voltage measurements, electron energy loss spectroscopy, and spherical aberration-corrected electron microscopy, it was revealed that nickel/indium (oxy)hydroxides (NiOOH/In(OH)3) could be evolved from the initial NiS2/In2.77S4 via both electrochemical and chemical-driven methods. The electrochemical-driven phase featured abundant bridging oxygen-deficient [NiO6]-[InO6] units at the interfaces of NiOOH/In(OH)3, facilitating a synergistic effect between active Ni and In sites, thus enabling an enhanced alkaline 2e- ORR capability than that of chemical-driven process. Remarkably, electrochemically induced NiOOH/In(OH)3 exhibited exceptional performance, achieving H2O2 selectivity of >90% across the wide potential window (up to 0.4 V) with a peak selectivity of >99%. Notably, within the flow cell, a current density exceeding 200 mA cm-2 was sustained for over 20 h, together with an impressive Faradaic efficiency of approximately 90% and a hydrogen peroxide production rate surpassing 4 mol g-1 h-1.

Electronic Properties and CO2-Selective Adsorption of (NiB)n (n = 1~10) Clusters: A Density Functional Theory Study.

In this study, we investigated the electronic properties and selective adsorption for CO2 of nickel boride clusters (NiB)n, (n = 1~10) using the first principles method. We optimized the structures of the clusters and analyzed their stability based on binding energy per atom. It was observed that (NiB)n clusters adopt 3D geometries from n = 4, which were more stable compared to the plane clusters. The vertical electron affinity, vertical ionization energy, chemical potential, and highest occupied molecular orbital (HOMO)-lowest unoccupied molecular orbital (LUMO) gap were calculated. Our results revealed that (NiB)6 and (NiB)10, with high chemical potential, exhibit a higher affinity for CO2 adsorption due to a charge delivery channel that forms along the Ni→B→CO2 path. Notably, (NiB)10 demonstrated a more practical CO2 desorption temperature, as well as a broader window for the selective adsorption of CO2 over N2. The density of states analysis showed that the enhanced CO2 adsorption on (NiB)10 can be attributed to the synergistic effect between Ni and B, which provides more active sites for CO2 adsorption and promotes the electron transfer from the surface to the CO2 molecule. Our theoretical results imply that (NiB)10 should be a promising candidate for CO2 capture.

Local Photothermal Effect Enabling Ni3 Bi2 S2 Nanoarray Efficient Water Electrolysis at Large Current Density.

In terms of the large-scale hydrogen production by water electrolysis, achieving the bifunctional electrocatalyst with high efficiency and stability at high current densities is of great significance but still remains a grand challenge. To address this issue, herein, one unique hybrid electrode is synthesized with the local photothermal effect (LPTE) by supporting the novel ternary nickel (Ni)bismuth (Bi)sulfur (S) nanosheet arrays onto nickel foam (Ni3 Bi2 S2 @NF) via a one-pot hydrothermal reaction. The combined experimental and theoretical observations reveal that owing to the intrinsic LPTE action of Bi, robust phase stability of Ni3 Bi2 S2 as well as the synergistic effect with hierarchical configuration, upon injecting the light, the as-prepared Ni3 Bi2 S2 exhibits remarkably improved efficiency of 44% and 35% for the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER), respectively. Such enhanced values are also comparable to those performed in working media heated to 80 °C. In addition, the overall water splitting system by using Ni3 Bi2 S2 @NF as bifunctional electrodes only delivers an ultralow voltage of 1.40 V at 10 mA cm-2 under LPTE, and can be stable more than 36 h at 500-1000 mA cm-2 . More broadly, even worked at 0-5 °C, alkaline simulated seawater and high salt seawater, the electrodes still show apparent LPTE effect for improving catalytic efficiency.

The role of tonal information during spoken-word recognition in Chinese: Evidence from a printed-word eye-tracking study.

Two experiments were conducted to investigate the extent to which the lexical tone can affect spoken-word recognition in Chinese using a printed-word paradigm. Participants were presented with a visual display of four words-namely, a target word (e.g., , xiang4xian4, "quadrant"), a tone-consistent phonological competitor (e.g., , xiang4ce4, "photo album"), or a tone-inconsistent phonological competitor (e.g., , xiang1cai4, "coriander"), and two unrelated distractors. Simultaneously, they were asked to listen to a spoken target word presented in isolation (Experiment 1) or embedded in neutral/predictive sentence contexts (Experiment 2), and then click on the target word on the screen. Results showed significant phonological competitor effects (i.e., the fixation proportion on the phonological competitor was higher than that on the distractors) under both tone conditions. Specifically, a larger phonological competitor effect was observed in the tone-consistent condition than in the tone-inconsistent condition when the spoken word was presented in isolation and the neutral sentence contexts. This finding suggests a partial role of lexical tone in constraining spoken-word recognition. However, when embedded in a predictive sentence context, the phonological competitor effect was only observed in the tone-consistent condition and absent in the tone-inconsistent condition. This result indicates that the predictive sentence context can strengthen the role of lexical tone.

Effects of a Pd/Pt bimetal supported by a γ-Al2O3 surface on methane activation.

The catalytic removal of methane (CH4) in exhaust emissions of natural gas-fueled vehicles is still a major challenge for automotive manufacturers because of the high CH3-H bond energy and high concentrations of water (H2O). Density functional theory (DFT) calculations were employed to investigate the adsorption of CH4 and H2O, as well as the activation of CH4, on the surface of a Pd-Pt bimetal supported by γ-Al2O3. These are significant factors for catalytic combustion. Pt addition weakened the bonding of the intermediates and increased the availability of electrons on the surface. Besides this, the γ-Al2O3 surface and Pt were both beneficial for preventing the aggregation of clusters. CH4 and H2O adsorption, as well as the detailed mechanism of CH4 activation on the Pd-Pt/γ-Al2O3 surfaces were simulated. The results showed that a Pt/Pd ratio of three resulted in the best catalytic activity among the different ratios examined in the presence of H2O.

Double graphitic-N doping for enhanced catalytic oxidation activity of carbocatalysts.

Graphitic N (GrN) doping is an effective way to promote the catalytic oxidation activities of pristine graphene, but a low doping density still limits its practical use. Based on DFT calculations, a double graphitic N (GrN) doping method is proposed. When the two GrN atoms are located at two different but nearby hexatomic rings, the dissociation of O2 molecules is significantly facilitated and the subsequently formed oxygen groups remain active for SO2 oxidation. In contrast, if the two GrN atoms are located at the same hexatomic rings of graphene, sluggish carbonyl groups will be formed in spite of the dissociation of O2 molecules being extraordinarily preferred.

Changes in microbial population and chemical composition of corn stover during field exposure and effects on silage fermentation and in vitro digestibility.

OBJECTIVE: To effectively use corn stover resources as animal feed, the changes in microbial population and chemical composition of corn stover during field exposure, and their silage fermentation and in vitro digestibility were studied. METHODS: Corn cultivars (Jintian, Jinnuo, and Xianyu) stovers from 4 random sections of the field were harvested at the preliminary dough stage of maturity on September 2, 2015. The corn stover exposed in the field for 0, 7, 15, 30, 60, 90, and 180 d, and their silages at 60 d of ensiling were used for the analysis of microbial population, chemical composition, fermentation quality, and in vitro digestibility. Data were analyzed with a completely randomized 3×6 [corn stover cultivar (C)×exposure d (D)] factorial treatment design. Analysis of variance was performed using SAS ver. 9.0 software (SAS Institute Inc., Cary, NC, USA). RESULTS: Aerobic bacteria were dominant population in fresh corn stover. After ensiling, the lactic acid bacteria (LAB) became the dominant bacteria, while other microbes decreased or dropped below the detection level. The crude protein (CP) and water-soluble carbohydrate (WSC) for fresh stover were 6.74% to 9.51% and 11.75% to 13.21% on a dry matter basis, respectively. After exposure, the CP and WSC contents decreased greatly. Fresh stover had a relatively low dry matter while high WSC content and LAB counts, producing silage of good quality, but the dry stover did not. Silage fermentation inhibited nutrient loss and improved the fermentation quality and in vitro digestibility. CONCLUSION: The results confirm that fresh corn stover has good ensiling characteristics and that it can produce silage of good quality.

Ultrahigh-power supercapacitors based on highly conductive graphene nanosheet/nanometer-sized carbide-derived carbon frameworks.

In order to develop energy storage devices with high power performance, electrodes should hold well-defined pathways for efficient ionic and electronic transport. Herein, we demonstrate a highly conductive graphene nanosheet/nanometer-sized carbide-derived carbon framework (hcGNS/nCDC). In this architecture, nCDC possesses short transport paths for electrolyte ions, thus ensuring the rapid ions transportation. The excellent electrical conductivity of hcGNS can reduce the electrode internal resistance for the supercapacitor and thus endows the hcGNS/nCDC composite electrodes with excellent electronic transportation performance. Electrochemical measurements show that the cyclic voltammogram of hcGNS/nCDC can maintain a rectangular-like shape with the increase of the scan rate from 5 mV s-1 to 20 V s-1, and the specific capacitance retention is up to 51% even at a high scan rate of 20 V s-1, suggesting ultrahigh power performance, which, to the best of our knowledge, is among the best power performances reported so far for the carbon materials. Furthermore, the hcGNS/nCDC composite also shows an excellent cycling stability (no drop in its capacitance occurs even after 10000 cycles). This work demonstrates the advantage in the ultrahigh power performance for the framework having both short transport pathways for electrolyte ions and high electrical conductivity.

Silage preparation and fermentation quality of natural grasses treated with lactic acid bacteria and cellulase in meadow steppe and typical steppe.

OBJECTIVE: In order to improve fermentation quality of natural grasses, their silage preparation and fermentation quality in meadow steppe (MS) and typical steppe (TS) were studied. METHODS: The small-scale silages and round bale silages of mixed natural grasses in both steppes were prepared using the commercial lactic acid bacteria (LAB) inoculants Chikuso-1 (CH, Lactobacillus plantarum) and cellulase enzyme (AC, Acremonium cellulase) as additives. RESULTS: MS and TS contained 33 and 9 species of natural grasses, respectively. Stipa baicalensis in MS and Stipa grandi in TS were the dominant grasses with the highest dry matter (DM) yield. The crude protein (CP), neutral detergent fiber and water-soluble carbohydrate of the mixed natural grasses in both steppes were 8.02% to 9.03%, 66.75% to 69.47%, and 2.02% to 2.20% on a DM basis, respectively. All silages treated with LAB and cellulase were well preserved with lower pH, butyric acid and ammonia-N content, and higher lactic acid and CP content than those of control in four kinds of silages. Compared with CH- or AC-treated silages, the CH+ AC-treated silages had higher lactic acid content. CONCLUSION: The results confirmed that combination with LAB and cellulase may result in beneficial effects by improving the natural grass silage fermentation in both grasslands.

Pharmacokinetics of Maleic Acid as a Food Adulterant Determined by Microdialysis in Rat Blood and Kidney Cortex.

Maleic acid has been shown to be used as a food adulterant in the production of modified starch by the Taiwan Food and Drug Administration. Due to the potential toxicity of maleic acid to the kidneys, this study aimed to develop an analytical method to investigate the pharmacokinetics of maleic acid in rat blood and kidney cortex. Multiple microdialysis probes were simultaneously inserted into the jugular vein and the kidney cortex for sampling after maleic acid administration (10 or 30 mg/kg, i.v., respectively). The pharmacokinetic results demonstrated that maleic acid produced a linear pharmacokinetic phenomenon within the doses of 10 and 30 mg/kg. The area under concentration versus time curve (AUC) of the maleic acid in kidney cortex was 5-fold higher than that in the blood after maleic acid administration (10 and 30 mg/kg, i.v., respectively), indicating that greater accumulation of maleic acid occurred in the rat kidney.

The Drug-Drug Effects of Rhein on the Pharmacokinetics and Pharmacodynamics of Clozapine in Rat Brain Extracellular Fluid by In Vivo Microdialysis.

Clozapine, an atypical antipsychotic agent, is highly effective in treatment-resistant schizophrenia; however, its major side effect is constipation. Instead of laxatives, rhein is a pharmacologically active component found in Rheum palmatum L., a medicinal herbal remedy for constipation. The purpose of this study is to determine whether rhein impacts the pharmacokinetics (PK) and pharmacodynamics (PD) of clozapine in brain when used to relieve clozapine-induced constipation. Here, we have investigated not only the PK of clozapine in blood but also the effects of rhein on the PK of clozapine in blood and in brain extracellular fluid together with the PD effects on neurotransmitters in extracellular fluid. The concentrations of clozapine and norclozapine in biologic samples were measured by ultra-performance liquid chromatography-tandem mass spectrometry. The drug-drug effects of rhein on extracellular neurotransmitter efflux in the rat medial prefrontal cortex (mPFC) produced by clozapine were assayed by high-performance liquid chromatography-electrochemical detection. The results demonstrate that the clozapine PK was nonlinear. Pretreatment with rhein for 7 days increased the total blood concentration of clozapine, but significantly reduced the unbound clozapine concentrations in the mPFC by approximately 3-fold. Furthermore, 7 days of rhein pretreatment thoroughly abolished the efflux of dopamine and its metabolite (3,4-dihydroxyphenylacetic acid) and altered the profile of homovanillic acid, another metabolite of dopamine, in the mPFC. In conclusion, rhein was found to substantially decrease clozapine and norclozapine concentrations in the mPFC dialysate, and this is accompanied by lower concentrations in the neurotransmitters in the same biophase. These findings suggest that a detailed clinical study for drug-drug interactions is recommended.

Local pelvic irradiation modulates Pharmacokinetics of 5-Fluorouracil in the plasma but not in the Lymphatic System.

BACKGROUND: 5-fluorouracil (5-FU) is employed to enhance radiotherapy (RT) effect. Here, we evaluated the influence of whole-pelvic irradiation on the pharmacokinetics (PK) of 5-FU in plasma and lymphatic system of rats as the experimental model. METHODS: RT with 2 Gy was delivered to the whole pelvis of Sprague-Dawley rats. 5-FU at 100 mg/kg was intravenously infused 24 hours after radiation. The pharmacokinetics of 5-FU in plasma and lymphatic system were calculated. RESULTS: RT at 2 Gy reduced the area under the plasma concentration vs. time curve and mean residence time of 5-FU by 21.5% and 31.5%, respectively compared with those of non-RT controls. By contrast, RT at 2 Gy increased drug clearances of 5-FU by 28.2% when compared with those of non-RT controls. There was no significant difference in T1/2, Cmax and Vss in plasma between both groups. Intriguingly, 5-Fu could be detected in the lymphatic system. In addition, the AUC in 5-FU without and with RT was 3.3-fold and 4.9-fold greater for lymph than for plasma, respectively. Compared with the non-RT group, the RT group showed increase in distribution of 5-FU in the lymphatic system (p = 0.001). CONCLUSIONS: The local whole pelvic RT at 2 Gy could modulate systemic PK of 5-FU in plasma of rats and intravenous 5-FU passing into the lymphatic system was proved. The metabolism of 5-FU might be modulated by RT but the distribution of 5-FU from blood circulation to the lymphatic system might not be changed. The RT-PK phenomena in plasma provide references for adjustment of drug administration. Chemotherapy drugs entering the lymphatic system is worthy of further investigation.

Determination of bioactive components in Chinese herbal formulae and pharmacokinetics of rhein in rats by UPLC-MS/MS.

Rhein (4,5-dihydroxy-9,10-dioxoanthracene-2-carboxylic acid, cassic acid) is a pharmacological active component found in Rheum palmatum L. the major herb of San-Huang-Xie-Xin-Tang (SHXXT), a medicinal herbal product used as a remedy for constipation. Here we have determined multiple bioactive components in SHXXT and investigated the comparative pharmacokinetics of rhein in rats. A sensitive and specific method combining liquid chromatography with electrospray ionization tandem mass spectrometry has been developed and validated to simultaneously quantify six active compounds in the pharmaceutical herbal product SHXXT to further study their pharmacokinetics in rats. Multiple reaction monitoring (MRM) was employed for quantification with switching electrospray ion source polarity between positive and negative modes in a single run. There were no significant matrix effects in the quantitative analysis and the mean recovery for rhein in rat plasma was 91.6%±3.4%. The pharmacokinetic data of rhein demonstrate that the herbal formulae or the single herbal extract provide significantly higher absorption rate than the pure compound. This phenomenon suggests that the other herbal ingredients of SHXXT and rhubarb extract significantly enhance the absorption of rhein in rats. In conclusion, the herbal formulae (SHXXT) are more efficient than the single herb (rhubarb) or the pure compound (rhein) in rhein absorption.

[Roles of heme oxygenase-1 promoting regeneration of peribiliary vascular plexus in bile duct ischemia/reperfusion injury].

OBJECTIVE: To study the effect of heme oxygenase-1 (HO-1) on peribiliary vascular plexus (PVP) in rat bile duct ischemia/reperfusion injury. METHODS: Total 128 male SD rats were randomly divided into saline group (Saline), empty virus group (Adv), induced group (Adv-HO-1) and suppressed group (HO-1 siRNA), and there were 32 rats in each group. Rats were injected using 0.5 ml of saline, empty adenovirus, HO-1 adenovirus and siRNA adenovirus (2×10(9) TU/rat) via the dorsal penile vein 24 hours before surgery. Liver function was analyzed at 1 hour and 1, 7, 14 days after reperfusion. HO-1, hypoxiainducible factor-1α (HIF-1α), stromal cell derived factor-1α (SDF-1α) and vascular endothelial growth factor (VEGF) protein content was analyzed by Western blot. The endothelial progenitor cells (EPCs) ratio in the liver and peripheral blood was detected by flow cytometry. Small vascular around the bile duct was observed by α-smooth muscle actin and von Willebrand factor double immunofluorescence staining. RESULTS: Reduced liver injury and higher expression of HIF-1α, SDF-1α and VEGF in the induced group after surgery (q = 5.68-7.52, P < 0.01). EPCs ratio in the liver and peripheral blood was significantly higher in the induced group than saline group (q = 12.14 and 15.26, P < 0.01), and the suppressed group at 7 days after surgery were less than saline group significantly (q = 4.83 and 5.07, P < 0.01). In comparison to the suppressed group, higher density of small vascular around the bile duct was seen in the liver tissue of induced group. CONCLUSIONS: HO-1 can induce the expression of HIF-1α, SDF-1α and VEGF, and mobilize the release of EPCs to the peripheral from the bone marrow. EPCs migrate to the liver and promote damaged PVP repair and regeneration.

Head and neck irradiation modulates pharmacokinetics of 5-fluorouracil and cisplatin.

BACKGROUND: 5-fluorouracil (5-FU) and cisplatin (CDDP) are used to enhance radiotherapy (RT) effect for head and neck (HN) cancers. However, the effect of local RT on systemic chemotherapeutics remains unclear. Here, we evaluated the influence of HN irradiation on the pharmacokinetics (PK) of 5-FU and CDDP in rats as experimental model. METHODS: The radiation dose distributions of HN cancer patients were determined for the low dose areas, which are generously deposited around the target volume. Two Gy and 0.5 Gy RT were selected. Single-fraction radiation was delivered to the HN of Sprague-Dawley rats. 5-FU at 100 mg/kg or CDDP at 5 mg/kg was intravenously infused 24 hours after radiation. RESULTS: Radiation at 2 Gy reduced the area under the plasma concentration vs. time curve (AUC) of 5-FU and CDDP by 16% and 29% compared to non-irradiated controls, respectively. This was accompanied by incremental total plasma clearance values. Intriguingly, low dose radiation at 0.5 Gy resulted in a similar pharmacokinetic profile, with a 17% and 33% reduction in the AUC of 5-FU and CDDP, respectively. The changes in AUC of bile, which increases with RT, were opposite to AUC of plasma for both drugs. CONCLUSIONS: The local HN RT could modulate systemic PK of 5-FU and CDDP in rats. This unexpected RT-PK phenomena may provide a reference for adjustment of drug administration and is worthy of further investigation. TRIAL REGISTRATION: ClinicalTrials.gov ID NCT01755585 and NCT01609114.

Pharmacokinetics of dibutyl phthalate (DBP) in the rat determined by UPLC-MS/MS.

Dibutyl phthalate (DBP) is commonly used to increase the flexibility of plastics in industrial products. However, several plasticizers have been illegally used as clouding agents to increase dispersion of aqueous matrix in beverages. This study thus develops a rapid and validated analytical method by ultra-performance liquid chromatography with tandem mass spectrometry (UPLC-MS/MS) for the evaluation of pharmacokinetics of DBP in free moving rats. The UPLC-MS/MS system equipped with positive electrospray ionization (ESI) source in multiple reaction monitoring (MRM) mode was used to monitor m/z 279.25→148.93 transitions for DBP. The limit of quantification for DBP in rat plasma and feces was 0.05 µg/mL and 0.125 µg/g, respectively. The pharmacokinetic results demonstrate that DBP appeared to have a two-compartment model in the rats; the area under concentration versus time (AUC) was 57.8 ± 5.93 min µg/mL and the distribution and elimination half-life (t(1/2,α) and t(1/2,ß)) were 5.77 ± 1.14 and 217 ± 131 min, respectively, after DBP administration (30 mg/kg, i.v.). About 0.18% of the administered dose was recovered from the feces within 48 h. The pharmacokinetic behavior demonstrated that DBP was quickly degraded within 2 h, suggesting a rapid metabolism low fecal cumulative excretion in the rat.

Determination and pharmacokinetics of di-(2-ethylhexyl) phthalate in rats by ultra performance liquid chromatography with tandem mass spectrometry.

Di-(2-ethylhexyl) phthalate (DEHP) is used to increase the flexibility of plastics for industrial products. However, the illegal use of the plasticizer DEHP in food and drinks has been reported in Taiwan in 2011. In order to assess the exact extent of the absorption of DEHP via the oral route, the aim of this study is to develop a reliable and validated ultra performance liquid chromatography with tandem mass spectrometry (UPLC-MS/MS) method to evaluate the oral bioavailability of DEHP in rats. The optimal chromatographic separation of DEHP and butyl benzyl phthalate (BBP; used as internal standard) were achieved on a C18 column. The mobile phase was consisted of 5 mM ammonium acetate-methanol (11:89, v/v) with a flow rate of 0.25 mL/min. The monitoring ion transitions were m/z 391.4 → 149.0 for DEHP and m/z 313.3 → 149.0 for BBP. The mean matrix effects of DEHP at low, medium and high concentrations were 94.5 ± 5.7% and 100.1 ± 2.3% in plasma and feces homogenate samples, respectively. In conclusion, the validated UPLC-MS/MS method is suitable for analyzing the rat plasma sample of DEHP and the oral bioavailability of DEHP was about 7% in rats.

Directed regulation mechanism on chlorine substitution of PCDD/Fs isomers based on quantum chemical computation.

BACKGROUND: Chlorine substitution has been considered as one of the key steps of polychlorinated dibenzodioxin/furan (PCDD/Fs) generation. The introduction of oxygen carriers (OCs), especially in chemical looping combustion (CLC), provides the platform of directed regulation for the chlorine substitution process. METHODS: Density functional theory (DFT) calculations with code VASP 5.4 were employed to investigate the free energy of PCDD/Fs adsorption on different surfaces. 12378-PCDD, which is the product of a one-step chlorine substitution for toxic 2378-PCDD, has been selected as the calculation case, and the regulation mechanisms on the inter-isomeric conversion of 12378-PCDD were identified by calculating the energy barrier and action angle. RESULTS: It was found that the chlorine substitution of 12378-PCDD, particularly in 4# position, 9# position, and 6# position, emerged a tendency to increase the difficulty in turn, which conforms to the principle of distal preference. Besides, the influence from CaO adsorption on the crystalline surface of the iron-based oxygen carrier (OC) has been analyzed and it was verified that CaO adsorption can significantly increase the energy barrier for the chlorine substitution of 12378-PCDD. Meanwhile, the action angle was proposed to evaluate the parameters of adsorption process, and the adsorption of CaO can not only change the action angle between the 12378-PCDD molecule and the lattice surface, but also can modulate the energy barrier order of chlorine substitution among PCDD isomers. In addition, the loading component modulation was carried out to further confirm the feasibility of modulating the chloride substitution pathway, which proved the influence degree of loading component. And accordingly, the stretching analysis of the inactive component provides a theoretical basis for the subsequent study of the directional regulation of the PCDDs isomer generation pathway. Finally, the chlorine substitution rules and directed regulation mechanisms of PCDD/Fs isomers were obtained, which provides a modification direction for the structural components of OCs.

The infertile individual analysis based on whole-exome sequencing in chinese multi-ethnic groups.

BACKGROUND: Infertility is a common and rapidly growing health issue around the world. The genetic analysis based on the infertile population is crucial for intervention and treatment. OBJECTIVE: To find candidate gene locus led to azoospermia in Chinese multi-ethnic groups and provide theoretical guidance for the diagnosis of genetic diseases to progressively aggravated infertility patients and sterile offspring with ART. METHODS: The study based on whole-exome sequencing (WES) was presented for genetic characteristic analysis of multi-ethnics and identification of variants related to infertility in Xinjiang area of China. RESULTS: The frequency of pathogenic variants showed significant ethnic differences among four main ethnics in Xinjiang. The population structure analysis confirmed that the Hui was close to the Han population, the Kazak was close to the Uygur population, and there are three ancestry components in the four ethnics. In addition, ten candidate variants potentially regulated azoospermia were detected, and KNTC1 (rs7968222: G > T) was chosen to validate the association. Through the analysis in the valid group, the frequency of rs7968222 (G > T) has a significant difference in the azoospermia population (11.76%, 8/68) and normospermia population (4.63%, 35/756) (P < 0.001). Interestingly, the proportion of people with abnormal follicle-stimulating hormone (FSH) level in the group carrying rs7968222 (G > T) was significantly higher than non-carriers (P < 0.05). Therefore, rs7968222 may regulate spermatogenesis through affecting hormone level. CONCLUSION: Our study establishes the genetics analysis of Northwest China and finds a candidate gene locus KNTC1 (rs7968222: G > T), which is one of the genetic susceptibility factors for male azoospermia.