The essential amino acid tryptophan is a constituent of proteins and is also a substrate for two important biosynthetic pathways: the generation of neurotransmitter 5-hydroxytryptamine (serotonin) by ...tryptophan 5-hydroxylase, and the formation of kynurenine derivatives and nicotinamide adenine dinucleotides. The latter pathway is initiated by the enzymes tryptophan pyrrolase (tryptophan 2,3-dioxygenase, TDO) and indoleamine 2,3-dioxygenase (IDO). TDO is located in liver cells, whereas IDO is expressed in a variety of cells including monocyte-derived macrophages and dendritic cells and is preferentially induced by Th1-type cytokine interferon-γ. Tryptophan depletion via IDO is part of the cytostatic and antiproliferative activity mediated by interferon-γ in cells. In vivo tryptophan concentration can be measured by HPLC by monitoring its natural fluorescence (285 nm excitation and 365 nm emission wavelength). IDO activity is characterized best by the kynurenine to tryptophan ratio which correlates with concentrations of immune activation markers such as neopterin. Low serum/plasma tryptophan concentration is observed in infectious, autoimmune, and malignant diseases and disorders that involve cellular (Th1-type) immune activation as well as during pregnancy due to accelerated tryptophan conversion. Thus, in states of persistent immune activation, low tryptophan concentration may contribute to immunodeficiency. Decreased serum tryptophan can also effect serotonin biosynthesis and thus contribute to impaired quality of life and depressive mood. As such, monitoring tryptophan metabolism in chronic immunopathology provides a better understanding of the association between immune activation and IDO and its role in the development of immunodeficiency, anemia and mood disorders.
Agricultural irrigation water is essential for global food production. Climate change may significantly increase future atmosphere evaporative demand, which can further intensify local water stress, ...particularly in arid and semi-arid regions. In this study, we investigate climate change impacts on future irrigation water use (IWU) change, with a focus on a semi-arid (Zhangye) region in Northwest China. Specifically, this approach estimates crop water demand using Penman-Monteith-CO2 equation which is modified to account for atmospheric CO2 concentration impacts. The IWU is then calculated as the difference between crop water demand and effective precipitation. This approach is validated using observed IWU. Combined with climate projections from eight Earth System Models (ESMs), future (up to 2100) IWU changes under different CO2 emission scenarios are evaluated. Results demonstrate that our Penman-Monteith-CO2 approach is robust in IWU estimation, with a relative error of 2.4% during the validation period of 2015–2020. In the medium emission scenario (SSP245), IWU has a significant increasing trend of 1.4×105 m3/yr during 2021–2100, which is mainly attributed to the increased future atmospheric evaporation demand. Interestingly, IWU presents a decreasing trend of − 1.3×105 m3/yr for the high emission scenario (SSP585). This is because strongly elevated CO2 concentration levels can substantially increase crop water use efficiency – leading to reduced IWU, and this impact outweighs the increased atmospheric evaporation demand in the SSP585 scenario. Therefore, our study suggests that future IWU change is determined by both climate change and crop responses to atmospheric CO2 concentration. Finally, we highlight that adjusting crop patterns can reduce both the IWU mean and variation changes, which can potentially alleviate local water stress.
•We investigate irrigation change under elevated atmospheric CO2 concentration (CO2).•A physically based approach based on the modified Penman-Monteith equation is used.•Our approach is validated using multi-year observed irrigation data.•Crop water use efficiency responses to CO2 determine future irrigation water demand.•Adjusting crop types can significantly reduce future irrigation water use.
Abstract
For effective supply chain management, firms should focus on the relationship with their immediate stakeholders in the supply chain, namely, suppliers (upstream) and customers (downstream). ...This study investigates the impact of customer and supplier concentration as well as business strategy on sustainable financial growth, using financial data of 2021 Chinese non‐financial firms listed from 2006 to 2020. Additionally, it explores the moderating effect of business strategy on the relationship between customer and supplier concentration and sustainable financial growth. We find that higher customer and supplier concentration weakens the bargaining power of Chinese firms, which reduces their financial growth. However, an appropriate business strategy can help such firms achieve sustainable financial growth. We find that an aggressive business strategy moderates the negative impact of supplier concentration, while a defensive business strategy moderates the negative impact of customer concentration on financial growth. Finally, our results for the direct impact of customer and supplier concentration as well as business strategy hold for state‐owned and non‐state‐owned firms. However, we find differences regarding the moderating impact of business strategy between state‐owned and non‐state‐owned firms. Our results are robust to time and industry fixed effects, alternate proxies of financial growth and regression techniques.
Graphene oxide (GO) is a derivative of graphene nanosheet which is the most promising material of the decade in biomedical research. In particular, it has been known as an antimicrobial nanomaterial ...with good biocompatibility. In this study, we have synthesized and characterize GO and checked its antimicrobial property against different Gram-negative and Gram-positive multidrug drug resistant (MDR) hospital superbugs grown in solid agar-based nutrient plates with and without human serum through the utilization of agar well diffusion method, live/dead fluorescent staining and genotoxicity analysis. No significant changes in antibacterial activity were found in these two different conditions. We also compare the bactericidal capability of GO with some commonly administered antibiotics and in all cases the degree of inhibition is found to be higher. The data presented here are novel and show that GO is an effective bactericidal agent against different superbugs and can be used as a future antibacterial agent.
Display omitted
•Cu2O nanoparticles (NPs) with different morphologies can be prepared without high temperatures, high alkalis or adding any surfactants.•The morphologies of three different types of ...Cu2O can be easily controlled by adjusting concentration of OH–.•Cu2O nanospheres modified electrode presents the best sensing performance with a high sensitivity of 1438 μA mM−1 cm−2 and a low detection limit of 0.17 μM.
The controllable morphology engineering of active electrode materials is an effective strategy to obtain high performance non-enzymatic glucose sensing. Herein, different morphologic cuprous oxide (Cu2O nanospheres, nanocubes and microcubes) were controllably prepared by wet-chemistry precipitation technique through adjusting the OH– concentration. The growth and evolution mechanism of Cu2O at different OH– concentrations were extensively studied. Electrochemical testing revealed that Cu2O nanospheres had the highest sensitivity of 1438 μA mM−1 cm−2 and the lowest detection limit of 0.17 μM (S/N = 3), making them the best choice for glucose sensing. Additionally, the glucose detection range spanned two orders of concentration magnitude (0.5 μM ∼ 1.332 mM and 1.332 mM ∼ 3.832 mM), and the sensor displayed excellent anti-interference ability, reproducibility, and long-term stability. The electrode material also performed well in detecting glucose in real serum samples, indicating its practical applicability as a non-enzymatic sensor.
Inadequate pesticide application practices have many implications on human and environmental health. This research aimed at assessing pesticide risks on bees, non-target arthropods (NTAs) and ...earthworms, using PRIMET (Pesticide Risks in the Tropics to Man, Environment and Trade), a pesticide risk model, in the western highlands agro-ecological zone of Cameroon. For this purpose, information on pesticide usage stratagem (dosage, application interval and number of applications) and ecotoxicological properties (median lethal doses, persistence and no observable effect concentration) were gathered and entered into PRIMET to acquire the Predicted Exposure Concentration (PEC), No Effect Concentration (NEC) and Exposure Toxicity Ratio, ETR = PEC / NEC). The risk assessment revealed that the riskiest pesticides for earthworms were acetamiprid, glyphosate and imidacloprid with ETR values of 2963, 1667 and 419 respectively. For bees, acetamiprid, cypermethrin, emamectin benzoate, imidacloprid, and lambda-cyhalothrin were highly risky, with respective ETR values of 3252, 487, 278, 1383 and 295. The model predicted NTAs to be predominantly defenceless against cypermethrin and imidacloprid, as these compounds exhibited the topmost values of ETR of, 4.3 × 108 and 4.4 × 107, respectively. Other pesticides that were modelled to be highly risky to NTAs comprised chlorothalonil (ETR = 2076), cymoxanil (ETR = 1133), emamectin benzoate (ETR = 1700), lambda-cyhalothrin (ETR = 4900) and metalaxyl (ETR = 2303). Some compounds gave evidence of multi-level risks: imidacloprid exhibited high risk to all the organisms (earthworms, bees and NTAs); acetamiprid was risky to earthworms and bees, while cypermethrin, emamectin benzoate and lambda-cyhalothrin, were modelled to pose a risk to bees and NTAs. Regulating the use of these perilous pesticides should be encouraged in agroecosystems to protect environmental and human health.
Display omitted
•The riskiest pesticides for earthworms comprised acetamiprid, glyphosate and imidacloprid.•Acetamiprid, cypermethrin, emamectin benzoate, imidacloprid, and lambda-cyhalothrin were highly risky for bees.•Cypermethrin and imidacloprid exhibited the highest hazards to NTAs.•Imidacloprid, acetamiprid, cypermethrin, emamectin benzoate and lambda-cyhalothrin gave evidence of multi-level risks.
This paper synthesizes data on aerosol (particulate matter, PM) physical and chemical characteristics, which were obtained over the past decade in aerosol research and monitoring activities at more ...than 60 natural background, rural, near-city, urban, and kerbside sites across Europe. The data include simultaneously measured PM
10 and/or PM
2.5 mass on the one hand, and aerosol particle number concentrations or PM chemistry on the other hand. The aerosol data presented in our previous works (
Van Dingenen et al., 2004; Putaud et al., 2004) were updated and merged to those collected in the framework of the EU supported European Cooperation in the field of Scientific and Technical action COST633 (
Particulate matter:
Properties related to health effects). A number of conclusions from our previous studies were confirmed. There is no single ratio between PM
2.5 and PM
10 mass concentrations valid for all sites, although fairly constant ratios ranging from 0.5 to 0.9 are observed at most individual sites. There is no general correlation between PM mass and particle number concentrations, although particle number concentrations increase with PM
2.5 levels at most sites. The main constituents of both PM
10 and PM
2.5 are generally organic matter, sulfate and nitrate. Mineral dust can also be a major constituent of PM
10 at kerbside sites and in Southern Europe. There is a clear decreasing gradient in SO
4
2− and NO
3
− contribution to PM
10 when moving from rural to urban to kerbside sites. In contrast, the total carbon/PM
10 ratio increases from rural to kerbside sites. Some new conclusions were also drawn from this work: the ratio between ultrafine particle and total particle number concentration decreases with PM
2.5 concentration at all sites but one, and significant gradients in PM chemistry are observed when moving from Northwestern, to Southern to Central Europe. Compiling an even larger number of data sets would have further increased the significance of our conclusions, but collecting all the aerosol data sets obtained also through research projects remains a tedious task.
This study investigates the variation in open-hole strain/stress concentrations within the full deformation range of a ductile self-reinforced poly (ethylene terephthalate) (srPET) composite using ...the digital image correlation (DIC). Subsequently, DIC was applied to brittle open-hole polymethyl methacrylate (PMMA) for comparison. This demonstrated the influence of the ductility of srPET. The strain concentration factor (K
ɛ
) of PMMA was constant with a full deformation range and agreed with theoretical concentration factor (K
t
). By contrast, the K
ɛ
of srPETs was divided into five stages based on the propagation of yield extent (beginning from the hole edge) of the specimen, starting from K
t
and then increasing to the peak, followed by the lowest value.
The influence of temperature, CO₂ concentration and relative humidity on the carbonation depth and compressive strength of concrete was investigated. Meanwhile, phase composition, types of hydration ...products and microstructure characteristics of samples before and after the carbonation were analyzed by XRD and ESEM. Research results demonstrate that temperature, CO₂ concentration and relative humidity influence the carbonation depth and compressive strength of concrete significantly. There is a linear relationship between temperature and carbonation depth, as well as the compressive strength of concrete. CO₂ concentration and relative humidity present a power function and a polynomial function with carbonation depth of concrete, respectively. The concrete carbonation depth increases with the increase of relative humidity and reaches the maximum value when the relative humidity is 70%. Significant differences of phase composition, hydration products and microstructure are observed before and after the carbonation. Carbonization products of samples are different with changes of temperatures (10 °C, 20 °C and 30 °C). The result of crystal structure analysis indicates that the carbonation products are mainly polyhedral spherical vaterite and aragonite.
Osmosis through asymmetric membranes has been studied as a means of desalination via forward osmosis and power generation through a process known as pressure retarded osmosis. The primary obstacle to ...using asymmetric membranes for osmotic processes is the presence of internal concentration polarization, which significantly reduces the available osmotic driving force. This study explores the impact of both concentrative and dilutive internal concentration polarization on permeate water flux through a commercially available forward osmosis membrane. The coupling of internal and external concentration polarization is also investigated. A flux model that accounts for the presence of both internal and external concentration polarization for the two possible membrane orientations involving the feed and draw solutions is presented. The model is verified by data obtained from laboratory-scale experiments under well controlled conditions in both membrane orientations. Furthermore, the model is used to predict flux performance after hypothetical improvements to the membrane or changes in system conditions.
PDF
