Effects of Plant Community Type on Soil Methane Flux in Semiarid Loess Hilly Region,Central Gansu Province,China

Methane(CH_(4))is an important greenhouse gas second only to CO_(2)in terms of its greenhouse effect.Vegetation plays an important role in controlling soil CH_(4)fluxes,but the spatial variability of soil CH_(4)fluxes during vegetation restoration in Loess Hilly Region(LHR)is not fully understood.The effects of different plant community types[Medicago sativa grassland(MS);Xanthoceras sorbifolium forestland(XS);Caragana korshinskii bushland(CK);Hippophae rhamnoides shrubland(HR);and Stipa bungeana grassland(SB)]on soil CH_(4)flux in LHR were studied via the static chamber technique.The results showed that the five plant community types were sinks of soil CH_(4)in LHR,the plant community type significantly affected the soil CH_(4)flux,and the average CH_(4)uptake from high to low was in SB,HR,CK,MS,and XS.During the whole study period,the soil CH_(4)flux showed similar interannual variation.The maximum absorption of soil CH_(4)appeared in the growing season,while the minimum appeared in winter.Soil CH_(4)uptake was positively correlated with soil temperature and soil moisture.Soil temperature and moisture are important controlling factors for the temporal variability of soil CH_(4)flux.In LHR,the Stipa bungeana grassland is the more suitable plant community type for reducing soil CH_(4)emissions.In the process of vegetation restoration in LHR,the soil CH_(4)absorption potential of different plant community types should be considered,ecological benefits should be taken into account,and vegetation more suitable for mitigating the greenhouse effect should be selected.

Anti-diabetic effects and mechanisms of action of a Chinese herbal medicine preparation JQ-R in vitro and in diabetic KKAy mice

Refined-JQ(JQ-R) is a mixture of refined extracts from Coptis chinensis(Ranunculaceae),Astragalus membranaceus(Leguminosae) and Lonicera japonica(Caprifoliaceae), the three major herbs of Jin Qi-Jiang Tang tablet, a traditional Chinese medicine(TCM) formula. The mechanisms by which JQ-R regulates glucose metabolism and improves insulin sensitivity were studied in type 2 diabetic KK^(Ay)mice and insulin-resistant L6 myotubes. To investigate the mechanisms by which JQ-R improves insulin sensitivity, a model of insulin-resistant cells induced with palmitic acid(PA) was established in L6 myotubes. Glucose uptake and expression of factors involved in insulin signaling, stress, and inflammatory pathways were detected by immunoblotting. JQ-R showed beneficial effects on glucose homeostasis and insulin resistance in a euglycemic clamp experiment and decreased fasting insulin levels in diabetic KK^(Ay)mice. JQ-R also improved the plasma lipid profiles. JQ-R directly increased the activity of superoxide dismutase(SOD) and decreased malondialdehyde(MDA) as well as inducible nitric oxide synthase(iNOS) levels in insulin-resistant L6 cells, and elevated the insulin-stimulated glucose uptake with upregulated phosphorylation of AKT. The phosphorylation levels of nuclear factor kappa B(NF-κB p65), inhibitor of NF-κB(IκBα), c-Jun N-terminal kinase(JNK1/2) and extracellular-signal-regulated kinases(ERK1/2) were also changed after JQ-R treatment compared with the control group. Together these findings suggest that JQ-R improved glucose and lipid metabolism in diabetic KK^(Ay)mice. JQ-R directly enhanced insulin-stimulated glucose uptake in insulin-resistant myotubes with improved insulin signalling and inflammatory response and oxidative stress. JQ-R could be a candidate to achieve improved glucose metabolism and insulin sensitivity in type 2 diabetes mellitus.

Efficient single-component white light emitting diodes enabled by lanthanide ions doped lead halide perovskites via controlling Forster energy transfer and specific defect clearance

Currently,a major challenge for metal-halide perovskite light emitting diodes(LEDs)is to achieve stable and efficient white light emission due to halide ion segregation.Herein,we report a promising method to fabricate white perovskite LEDs using lanthanide(Ln^(3+))ions doped CsPbCl_(3) perovskite nanocrystals(PeNCs).First,K^(+)ions are doped into the lattice to tune the perovskite bandgap by partially substituting Cs^(+)ions,which are well matched to the transition energy of some Ln^(3+)ions from the ground state to the excited state,thereby greatly improving the Förster energy transfer efficiency from excitons to Ln3+ions.Then,creatine phosphate(CP),a phospholipid widely found in organisms,serves as a tightly binding surface-capping multi-functional ligand which regulates the film formation and enhances the optical and electrical properties of PeNC film.Consequently,the Eu^(3+)doped PeNCs based-white LEDs show a peak luminance of 1678 cd m^(-2) and a maximum external quantum efficiency(EQE)of 5.4%,demonstrating excellent performance among existing white PeNC LEDs from a single chip.Furthermore,the method of bandgap modulation and the defect passivation were generalized to other Ln^(3+)ions doped perovskite LEDs and successfully obtained improved electroluminescence(EL).This work demonstrates the comprehensive and universal strategies in the realization of highly efficient and stable white LEDs via single-component Ln^(3+)ions doped PeNCs,which provides an optimal solution for the development of low-cost and simple white perovskite LEDs.

The application of 2-NBDG as a fluorescent tracer for assessing hepatic glucose production in mice during hyperinsulinemic euglycemic clamp

Methods of performing insulin clamps vary between laboratories.Here we present a protocol of insulin clamping in conscious mice,with the significant advantage of avoiding multiple surgical catheterizations and non-physiologic metabolism during the induction of anesthesia.Using this technique we also established a new method for measuring hepa tic glucose production(HGP)using a fuorescent D-glucose analog,2-[N-(7-nitrobenz-2-oxa-1,3-diazol-4-yl)amino]-2-deoxyglu-cose(2-NBDG).To prove the reliability and feasibility of this method,whole-body insulin sensitivity was compared between conscious normal ICR mice and diabetic KK^(Ay) mice using the insulin clamp.Basal and clamp HGP was compared between normal C57 mice and diabetic db/db mice by using the modified clamp with 2-NBDG as a tracer.The glucose infusion rate(GIR),an index of insulin sensitivity,was significantly lower in KKAy mice than normal ICR mice.(6.2±1.3 mg/kg/min vs.31.3±2.9 mg/kg/min,P<0.001).The db/db mice also showed higher basal hepatic glucose production(25.8±2.2 mg/kg/min vs.16.7±2.5 mg/kg/min,P<0.05),higher clamp HGP after insulin suppression(7.3±1.0 mg/kg/min vs.0 mg/kg/min,P<0.001),and lower GIR(71.6±2.8 mg/kg/min vs.15.2±1.6 mg/kg/min,P<0.001)than that obtained with normal C57 mice.In conclusion,this is the first report of the application of 2-NBDG,rather than isotopic tracers,for the determination of HGP in vivo.

A cell-based fluorescent glucose transporter assay for SGLT2 inhibitor discovery

The sodium/glucose cotransporter 2(SGLT2)is responsible for the majority of glucose reabsorption in the kidney,and currently,SGLT2 inhibitors are considered as promising hypoglycemic agents for the treatment of type 2 diabetes mellitus.By constructing CHO cell lines that stably express the human SGLT2 transmembrane protein,along with a fluorescent glucose transporter assay that uses 2-[N-(7-nitrobenz-2-oxa-l,3-diazol-4-yl)amino]2-deoxyglucose(2-NBDG)as a glucose analog,we have developed a nonradioactive,cell-based assay for the discovery and characterization of SGLT2 inhibitors.

Domain-Decomposition Localized Method of Fundamental Solutions for Large-Scale Heat Conduction in Anisotropic Layered Materials

The localized method of fundamental solutions(LMFS)is a relatively new meshless boundary collocation method.In the LMFS,the global MFS approxima-tion which is expensive to evaluate is replaced by local MFS formulation defined in a set of overlapping subdomains.The LMFS algorithm therefore converts differential equations into sparse rather than dense matrices which are much cheaper to calcu-late.This paper makes thefirst attempt to apply the LMFS,in conjunction with a domain-decomposition technique,for the numerical solution of steady-state heat con-duction problems in two-dimensional(2D)anisotropic layered materials.Here,the layered material is decomposed into several subdomains along the layer-layer inter-faces,and in each of the subdomains,the solution is approximated by using the LMFS expansion.On the subdomain interface,compatibility of temperatures and heatfluxes are imposed.Preliminary numerical experiments illustrate that the proposed domain-decomposition LMFS algorithm is accurate,stable and computationally efficient for the numerical solution of large-scale multi-layered materials.