131 research outputs found

    EXPERIMENTAL TRIALS OF LIVE ATTENUATED AND INACTIVATED STAPHYLOCOCCUS AUREUS VACCINES IN RABBITS

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    This study was conducted as a preliminary step on the rabbits for comparative efficacy of different vaccines of Staphylococcus aureus. Typical alpha-beta Staph. aureus species from a clinically affected mastitic buffalo was isolated. After proper identification based on cultural and morphological characteristics and API-Staph Trac system, a selected Staph. aureus isolate was used to prepare four different mastitis vaccines (Bacterin, oil-adjuvanted, dextran sulphate adjuvanted and live attenuated) after confirmation for pathogenicity and antigenicity, followed by its safety and sterility evaluation. Vaccines were tried in 25 rabbits divided into 5 equal groups. A separate vaccine was administered s/c @ 0.2 ml per animal and boosted at 15 days later. It was found that IHA antibody titers were higher (GMT 32-128) in live attenuated, dextran sulphate adjuvanted (GMT 32-128) and oil-adjuvanted (GMT 16-64) than the bacterin treated (GMT 16-32) group. All the vaccines showed an apparent immune response than the unvaccinated control group

    Unraveling the Influence of Land-Use Change on δ 13C, δ 15N, and Soil Nutritional Status in Coniferous, Broadleaved, and Mixed Forests in Southern China: A Field Investigation

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    Natural isotopic abundance in soil and foliar can provide integrated information related to the long-term alterations of carbon (C) and nitrogen (N) cycles in forest ecosystems. We evaluated total carbon (TC), total nitrogen (TN), and isotopic natural abundance of C (δ 13C) and N (δ 15N) in soil and foliar of coniferous plantation (CPF), natural broadleaved forest (NBF), and mixed forest stands at three different soil depths (i.e., 0–10, 10–20, and 20–40 cm). This study also explored how soil available nutrients are affected by different forest types. Lutou forest research station, located in Hunan Province, central China, was used as the study area. Results demonstrated that the topsoil layer had higher TC and TN content in the mixed forest stand, resulting in a better quality of organic materials in the topsoil layer in the mixed forest than NBF and CPF. In general, soil TC, TN, and δ 15N varied significantly in different soil depths and forest types. However, the forest type did not exhibit any significant effect on δ 13C. Overall, soil δ 13C was significantly enriched in CPF, and δ 15N values were enriched in mixed forest. Foliar C content varied significantly among forest types, whereas foliar N content was not significantly different. No big differences were observed for foliar δ 15N and δ 13C across forest types. However, foliar δ 13C and δ 15N were positively related to soil δ 13C and δ 15N, respectively. Foliar N, soil and foliar C:N ratio, soil moisture content (SMC), and forest type were observed as the major influential factors affecting isotopic natural abundance, whereas soil pH was not significantly correlated. In addition, forest type change and soil depth increment had a significant effect on soil nutrient availability. In general, soil nutrient availability was higher in mixed forest. Our findings implied that forest type and soil depth alter TC, TN, and soil δ 15N, whereas δ 13C was only driven by soil depth. Moreover, plantations led to a decline in soil available nutrient content compared with NBF and mixed forest stand

    Intercropping of peanut–tea enhances soil enzymatic activity and soil nutrient status at different soil profiles in Subtropical Southern China

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    Intercropping is one of the most widely used agroforestry techniques, reducing the harmfulimpacts of external inputs such as fertilizers. It also controls soil erosion, increases soil nutrientsavailability, and reduces weed growth. In this study, the intercropping of peanut (ArachishypogaeaL.)was done with tea plants (Camellia oleifera), and it was compared with the mono-cropping of tea andpeanut. Soil health and fertility were examined by analyzing the variability in soil enzymatic activityand soil nutrients availability at different soil depths (0–10 cm, 10–20 cm, 20–30 cm, and 30–40 cm).Results showed that the peanut–tea intercropping considerably impacted the soil organic carbon(SOC), soil nutrient availability, and soil enzymatic responses at different soil depths. The activityof protease, sucrase, and acid phosphatase was higher in intercropping, while the activity of ureaseand catalase was higher in peanut monoculture. In intercropping, total phosphorus (TP) was 14.2%,34.2%, 77.7%, 61.9%; total potassium (TK) was 13.4%, 20%, 27.4%, 20%; available phosphorus (AP)was 52.9%, 26.56%, 61.1%; 146.15% and available potassium (AK) was 11.1%, 43.06%, 46.79% higherthan the mono-cropping of tea in respective soil layers. Additionally, available nitrogen (AN) was51.78%, 5.92%, and 15.32% lower in the 10–20 cm, 20–30 cm, and 30–40 cm layers of the intercroppingsystem than in the mono-cropping system of peanut. Moreover, the soil enzymatic activity wassignificantly correlated with SOC and total nitrogen (TN) content across all soil depths and croppingsystems. The depth and path analysis effect revealed that SOC directly affected sucrase, protease,urease, and catalase enzymes in an intercropping system. It was concluded that an increase in the soilenzymatic activity in the intercropping pattern improved the reaction rate at which organic matterdecomposed and released nutrients into the soil environment. Enzyme activity in the decompositionprocess plays a vital role in forest soil morphology and function. For efficient land use in the croppingsystem, it is necessary to develop coherent agroforestry practices. The results in this study revealedthat intercropping certainly enhance soil nutrients status and positively impacts soil conservation.The funding sources include the National Science and Technology Support Grant ofChina (2015BAD07B0503), Forestry Science and Technology Promotion Project of China (No. 122017) and Postdoctoral research funding of Central South University of Forestry and Technology(70702-45200003)

    Investigation of input and output energy for wheat production : a comprehensive study for Tehsil Mailsi (Pakistan)

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    The global increasing food demand can be met by efficient energy utilization in mechanized agricultural productions. In this study, input–output energy flow along with CO2 emissions for different wheat production cases (C-I to C-V) were investigated to identify the one that is most energy-efficient and environment-friendly case. Data and information about input and output sources were collected from farmers through questionnaires and face-to-face interviews. Input and output sources were converted into energy units by energy equivalents while CO2 emissions were calculated by emission equivalents. Data envelopment analysis (DEA) was conducted to compare technical efficiencies of the developed cases for optimization of inputs in inefficient cases. Results revealed that case C-Ⅴ (higher inputs, larger fields, the tendency of higher fertilizer application and tillage operations) has the highest energy inputs and outputs than the rest of the cases. Moreover, it possesses the lowest energy use efficiency and energy productivity. The highest CO2 emissions (1548 kg-CO2/ha) referred to C-Ⅴ while lowest emissions per ton of grain yield were determined in C-Ⅳ (higher electricity water pumping, moderate energy input). The grain yield increases directly with input energy in most of the cases, but it does not guarantee the highest values for energy indices. C-Ⅲ (moderate irrigations, educated farmers, various fertilizer applications) was found as an optimum case because of higher energy indices like energy use efficiency of 4.4 and energy productivity of 153.94 kg/GJ. Optimum input and better management practices may enhance energy proficiency and limit the traditionally uncontrolled CO2 emissions from wheat production. Therefore, the agricultural practices performed in C-Ⅲ are recommended for efficient cultivation of wheat in the studied area.The global increasing food demand can be met by efficient energy utilization in mechanized agricultural productions. In this study, input–output energy flow along with CO2 emissions for different wheat production cases (C-I to C-V) were investigated to identify the one that is most energy-efficient and environment-friendly case. Data and information about input and output sources were collected from farmers through questionnaires and face-to-face interviews. Input and output sources were converted into energy units by energy equivalents while CO2 emissions were calculated by emission equivalents. Data envelopment analysis (DEA) was conducted to compare technical efficiencies of the developed cases for optimization of inputs in inefficient cases. Results revealed that case C-Ⅴ (higher inputs, larger fields, the tendency of higher fertilizer application and tillage operations) has the highest energy inputs and outputs than the rest of the cases. Moreover, it possesses the lowest energy use efficiency and energy productivity. The highest CO2 emissions (1548 kg-CO2/ha) referred to C-Ⅴ while lowest emissions per ton of grain yield were determined in C-Ⅳ (higher electricity water pumping, moderate energy input). The grain yield increases directly with input energy in most of the cases, but it does not guarantee the highest values for energy indices. C-Ⅲ (moderate irrigations, educated farmers, various fertilizer applications) was found as an optimum case because of higher energy indices like energy use efficiency of 4.4 and energy productivity of 153.94 kg/GJ. Optimum input and better management practices may enhance energy proficiency and limit the traditionally uncontrolled CO2 emissions from wheat production. Therefore, the agricultural practices performed in C-Ⅲ are recommended for efficient cultivation of wheat in the studied area.King Saud University, Riyadh, Saudi Arabi

    Morpho-physiological growth performance and phytoremediation capabilities of selected xerophyte grass species toward Cr and Pb stress

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    Being sessile organisms, plants cannot escape unwanted changes in the environment. The rapid human population explosion caused significant environmental problems. Heavy metals produced through various sources can cause severe damage to living organisms. The study was planned to evaluate four grass species’ morpho-physiological growth characteristics and phytoremediation capabilities under chromium (Cr) and lead stress (Pb) in the arid climate. Typha angustifolia, Tragus roxburghii, Aeluropus logopoides, and Cenchrus ciliaris grass species were used for the study. One-year-old stubbles from the Cholistan desert were used for the experiment. Cr treatments in the form of K2Cr2O7 were applied at 0, 20, 40, and 80 mg L–1, whereas Pb was applied as PbCl2 at 0, 50, 200, and 500 mg L–1 as control, low, moderate and high-stress, respectively. After 6 weeks of heavy metals treatments, plants were harvested and analyzed for growth performance and phytoremediation capabilities. Results depicted that, regarding morphological attributes, T. angustifolia performed better, followed by C. ciliaris; no clear pattern was observed for T. roxburghii and A. logopoides. The CO2 assimilation rate (Co2d) and water use efficiency (WUE) increased as the heavy metal stress increased in all species under both metals. In contrast, total chlorophyll content was higher under low stress. Other physiological parameters, such as relative humidity (RHd), net photosynthetic rate (A), transpiration rate (E), stomatal conductance (Gs), leaf internal CO2 concentration (Ci) and membrane stability index (MSI) gradually decreased as the Cr, and Pb stress levels increased among all the species. Moreover, Cr and Pb absorption contents of T. angustifolia were higher than the other three species at each stress level. Overall, T. angustifolia thrived against heavy metals stress and showed higher biomass, maximum photosynthetic measurements, WUE and higher metal absorption among all the selected species. Results concluded that although all the selected species behaved fine under stress conditions, T. angustifolia performance was better; thus, it can be used to remediate the soil near industrial estates

    Perspectives of plantation forests in the sustainable forest development of China

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    Modern forestry is gradually moving towards man-made forests on a large scale. Plantations with advanced forestry system have been introduced with the goal of sustainable forestry development and to enhance social, ecological, and economic benefits. Forest plantations with native and exotic species have been established in China and worldwide with shorter rotation cycles than natural forests. In this paper, we discuss the role and perspectives of plantation forests in the Chinese sustainable forest development, the evolution of various plantation programs, the ecological effects of plantations, and the measures to improve plantation forestry. The Chinese government has given substantial importance to nurturing plantation forest resources through various large scale afforestation programs. In 2019, the total area covered by plantations in China reached 79.54 million ha, with a stock volume of 3.39 billion mÂł (59.30 mÂł per ha); coniferous forests (26.11 million ha, 32.83%) and broad-leaved forests (26.45 million ha, 33.25%) are the dominant types. Plantations have been primarily distributed in the central and southern parts of the country. Plantations with fast-growing and high-yielding tree species facilitated Chinese afforestation activities and improved the administration of forest production, which effectively boosted the forest industry. Plantation forest resources offer many potential productive, economic, and social advantages, though they are also associated with a loss of biodiversity and climate change makes them likely susceptible to disease and insect attack. Appropriate forest management practices during planning, execution, and maintenance of plantations can contribute to the conservation, promotion, and restoration of biodiversity, with the final aim of attaining a balance between having forest plantations and natural forests.We thank the great help from two anonymous reviews. We also thank our friend Chris Ijeoma for the grammar checking of the manuscript. The funding sources included the Postdoctoral research funding of Central South University of Forestry and Technology, Changsha, China (70702-4520 0003

    Spatial distribution of carbon dynamics and nutrient enrichment capacity in different layers and tree tissues of Castanopsis eyeri natural forest ecosystem

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    Forest ecosystem carbon (C) storage primarily includes vegetation layers C storage, litter C storage, and soil C storage. The precise assessment of forest ecosystem C storage is a major concern that has drawn widespread attention in global climate change worldwide. This study explored the C storage of different layers of the forest ecosystem and the nutrient enrichment capacity of the vegetation layer to the soil in the Castanopsis eyeri natural forest ecosystem (CEF) present in the northeastern Hunan province, central China. The direct field measurements were used for the estimations. Results illustrate that trunk biomass distribution was 48.42% and 62.32% in younger and over-mature trees, respectively. The combined biomass of the understory shrub, herb, and litter layers was 10.46 t·hm−2, accounting for only 2.72% of the total forest biomass. On average, C content increased with the tree age increment. The C content of tree, shrub, and herb layers was 45.68%, 43.08%, and 35.76%, respectively. Litter C content was higher in the undecomposed litter (44.07 %). Soil C content continually decreased as the soil depth increased, and almost half of soil C was stored in the upper soil layer. Total C stored in CEF was 329.70 t·hm−2 and it follows the order: tree layer > soil layer > litter layer > shrub layer > herb layer, with C storage distribution of 51.07%, 47.80%, 0.78%, 0.25%, and 0.10%, respectively. Macronutrient enrichment capacity from vegetation layers to soil was highest in the herb layer and lowest in the tree layer, whereas no consistent patterns were observed for trace elements. This study will help understand the production mechanism and ecological process of the C. eyeri natural forest ecosystem and provide the basics for future research on climate mitigation, nutrient cycling, and energy exchange in developing and utilizing sub-tropical vegetationThis research was financially supported by research funding from Central South University of Forestry and Technology and the Hunan province finance department (No.70702-45200003

    TiO2 encrusted MXene as a High-Performance anode material for Li-ion batteries

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    TiO2 has the potential to be a viable anode material for high-power lithium-ion batteries (LIBs). However, the lower electronic conductivity of TiO2 limits its practical applications. Here, the synthesis of novel TiO2 decorated Ti3C-MXene anode for LIBs using in-situ hydrolysis is discussed. MXenes are well known for their outstanding structural stability and superior electronic conductivities; thus, using MXenes as a host material for TiO2 may improve its structural and electrical characteristics. Scanning and transmission electron microscopy (SEM & TEM) examination revealed that the in-situ method resulted in a uniform and comformal coating of TiO2 (27.5 nm) on the inner and outer surfaces of MXene surfaces. BET analysis revealed that the larger surface area of MXene-TiO2 nanocomposite enhanced the active sites for lithium intercalation, which improved electrochemical performance. Furthermore, electrochemical impedance spectroscopy (EIS) analysis revealed faster kinetics for MXene-TiO2 materials when compared to the TiO2 anode. Compared to pristine TiO2 anode, 5 wt% MXene-TiO2 nanocomposite showed significantly better electrochemical performance, with an electrochemical capacity of around 200 mAhg?1 at 0.1C. Nanocomposites based on MXene-TiO2 exhibit outstanding electrochemical performance, indicating the potential for using MXene-based nanocomposites as an anode in high-performance lithium-ion batteries.Statements made herein are solely the responsibility of the authors. Microstructural analyses (FE-SEM and HR-TEM) were accomplished at the Central Laboratory Unit (CLU), Qatar University, Doha, Qatar. Funding: This work was supported by Qatar National Research Fund (a member of the Qatar Foundation) [NPRP Grant # NPRP11S-1225-17128]; the Qatar University Internal Grant, [QUCG-CENG-20/21-2].Scopu

    Fiber guiding at the Dirac frequency beyond photonic bandgaps

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    Light trapping within waveguides is a key practice of modern optics, both scientifically and technologically. Photonic crystal fibers traditionally rely on total internal reflection (index-guiding fibers) or a photonic bandgap (photonic-bandgap fibers) to achieve field confinement. Here, we report the discovery of a new light trapping within fibers by the so-called Dirac point of photonic band structures. Our analysis reveals that the Dirac point can establish suppression of radiation losses and consequently a novel guided mode for propagation in photonic crystal fibers. What is known as the Dirac point is a conical singularity of a photonic band structure where wave motion obeys the famous Dirac equation. We find the unexpected phenomenon of wave localization at this point beyond photonic bandgaps. This guiding relies on the Dirac point rather than total internal reflection or photonic bandgaps, thus providing a sort of advancement in conceptual understanding over the traditional fiber guiding. The result presented here demonstrates the discovery of a new type of photonic crystal fibers, with unique characteristics that could lead to new applications in fiber sensors and lasers. The Dirac equation is a special symbol of relativistic quantum mechanics. Because of the similarity between band structures of a solid and a photonic crystal, the discovery of the Dirac-point-induced wave trapping in photonic crystals could provide novel insights into many relativistic quantum effects of the transport phenomena of photons, phonons, and electrons
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