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1.
Anal Chim Acta ; 1178: 338802, 2021 Sep 15.
Artigo em Inglês | MEDLINE | ID: mdl-34482881

RESUMO

Dispersive micro solid-phase extraction procedure using a novel and selective sorbent prepared from four components was developed as a sample preparation strategy for extracting five organophosphorus pesticides, including fenitrothion, malathion, ethion, and chlorpyrifos, and diazinon in several vegetables, fruit juices, and cow's milk samples. Due to the high importance of the sorbent in the microextraction process, the percentages of sorbent components, including metal-organic framework (ZIF-67), chitosan, magnetic Fe3O4 nanoparticles, and silica nanoparticles, were optimized by a simplex lattice mixture design. After optimizing the sorbent composite, effective parameters on the extraction of organophosphorus pesticides were optimized using a definitive screening design and Box-Behnken design, respectively. A surfactant (Triton X100) as a dispersion agent with a low volume (10 µL) was utilized in the microextraction procedure to reduce the sorbent dispersion time and increase the sorbent dispersion efficiency. Under the optimal conditions, linearity for the determination of fenitrothion, malathion, ethion, chlorpyrifos, and diazinon was in the concentration ranges of 0.13-1100, 0.27-1000, 0.38-1000, 0.21-1200, and 0.11-1100 ng mL-1 with a determination coefficient higher than 0.9906, respectively. The quantitation limits, detection limits, and relative standard deviations (n = 5) were lower than 0.38 ng mL-1, 0.11 ng mL-1, and 4.59% for the determination of organophosphorus pesticides. The method application for measuring OPPs on cucumber, carrot, tomato, apple juice, orange juice, and cow's milk indicated the presence of residual amounts of malathion in a cucumber sample, diazinon in a carrot sample, and chlorpyrifos in a tomato sample.


Assuntos
Resíduos de Praguicidas , Praguicidas , Animais , Sucos de Frutas e Vegetais , Limite de Detecção , Fenômenos Magnéticos , Leite/química , Compostos Organofosforados/análise , Praguicidas/análise , Extração em Fase Sólida , Verduras , Água/análise
2.
Chemosphere ; 283: 131183, 2021 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-34467940

RESUMO

Air-water interfaces are ubiquitous in nature, as manifested in the form of the surfaces of oceans, lakes, and atmospheric aqueous aerosols. The aerosol droplets interface, in particular, plays a critical role in numerous atmospheric chemistry processes. Methyl vinyl ketone (MVK) and methacrolein (MACR), two abundant volatile organic compounds, are the significant precursors of Criegee intermediates and secondary organic aerosol. In this work, the physicochemical properties of MVK and MACR at the air-water interface are studied from a theoretical perspective. The free energy wells of MVK and MACR occur at the air-water interface, and the absorption probabilities of them are 71% and 67%, respectively. Repulsion dominates the interactions between MVK/MACR and water molecules in the bulk region, while attraction is dominant at the interface. The two molecules tend to tilt at the interface, with the CC bond exposed at the outer interface. The most likely reaction scenario of O3-initiated MVK/MACR reaction in the troposphere is also determined for the first time. Based on the molecular dynamics simulation results, the activity sequence of MVK + O3 is given at four different environments by the density functional theory method: air-water interface, mineral clusters interface, bulk solution, and homogeneous gas. The interfacial water molecule can catalyze the reaction of MVK with O3, and the rate constant at the air-water interface is ~6 times larger than that on the mineral surface model. Compared with mineral particles, aqueous particles play a more significant role in modifying the reaction properties of atmospheric organic species.


Assuntos
Poluentes Atmosféricos , Água , Acroleína/análogos & derivados , Adsorção , Poluentes Atmosféricos/análise , Butanonas , Meio Ambiente , Água/análise
3.
Environ Monit Assess ; 193(10): 627, 2021 Sep 06.
Artigo em Inglês | MEDLINE | ID: mdl-34487242

RESUMO

Nickel determination is important because of its use in many industrial areas and its negative effects on human health. In this study, an ultraviolet-based photochemical vapor generation (UV-PVG) setup was combined with a T-shaped zirconium-coated slotted quartz tube-atom trapping (T-SQT-AT) apparatus to boost the sensitivity of a flame atomic absorption spectrophotometer for nickel determination. Nickel was separated from the sample matrix by converting it into its volatile species prior to online preconcentration by trapping on the zirconium-coated T-SQT inner surface. Analytical performance was maximized by optimizing all variable conditions. The limit of detection (LOD) and limit of quantification (LOQ) were found as 10 and 33 µg/L, respectively. Daphne tea and lake water samples were analyzed under optimum conditions, and there was no detectable nickel in the samples. For this purpose, spiking experiments were carried out for the samples in order to evaluate the applicability and accuracy of the method. The percent recovery values calculated for the two samples spiked at three different concentrations ranged between 90 and 112%. To our best knowledge, this is the first study in literature where UV-PVG was combined with T-SQT-AT for the determination of nickel in daphne tea and lake water samples prior to FAAS determination.


Assuntos
Daphne , Quartzo , Monitoramento Ambiental , Humanos , Lagos , Níquel/análise , Extratos Vegetais , Espectrofotometria Atômica , Chá , Água/análise , Zircônio
4.
Food Res Int ; 147: 110548, 2021 09.
Artigo em Inglês | MEDLINE | ID: mdl-34399525

RESUMO

Salmonella contamination of low-water activity (aw) foods poses a serious concern worldwide. The present study was conducted to assess the effects of drying conditions, food composition, and water activity on the desiccation tolerance and thermal resistance of S. Enteritidis FUA1946, S. Senftenberg ATCC43845 and S. Typhimurium ATCC13311 in pet food, binder formulation, and skim milk powder. The samples were wet inoculated with the individual Salmonella strains and were equilibrated to aw 0.33 and 0.75, followed by an isothermal treatment at 70 °C. The thermal inactivation data was fitted to the Weibull model. Irrespective of the aw, food composition and physical structure of the selected foods, strain S. Enteritidis FUA1946 displayed the highest desiccation and thermal resistance, followed by S. Senftenberg ATCC43845 and S. Typhimurium ATCC13311. The food matrix and strain type significantly (p < 0.05) influenced the thermal resistance of microorganisms in foods along with aw change during thermal treatments. To further study the effect of food composition, an additional set of experiments using dry inoculation of the resistant Salmonella strain in the low-aw foods was designed. Significant (p < 0.05) matrix-dependent interaction on Salmonella reduction was observed. The water adsorption isotherms of selected low-aw foods were measured at 20 and 70 °C to relate the thermal inactivation kinetics with the change in the aw. The characterization of thermal resistance of the Salmonella serovars in low-aw products with different compositions and aw in this study may be used for the validation of thermal challenge studies.


Assuntos
Salmonella enterica , Microbiologia de Alimentos , Temperatura Alta , Salmonella , Água/análise
5.
Int J Mol Sci ; 22(16)2021 Aug 04.
Artigo em Inglês | MEDLINE | ID: mdl-34445079

RESUMO

Solid-phase extraction (SPE) coupled to LC/MS/MS analysis is a valid approach for the determination of organic micropollutants (OMPs) in liquid samples. To remove the greatest number of OMPs from environmental matrices, the development of innovative sorbent materials is crucial. Recently, much attention has been paid to inorganic nanosystems such as graphite-derived materials. Graphene oxide has been employed in water-purification processes, including the removal of several micropollutants such as dyes, flame retardants, or pharmaceutical products. Polysaccharides have also been widely used as convenient media for the dispersion of sorbent materials, thanks to their unique properties such as biodegradability, biocompatibility, nontoxicity, and low cost. In this work, chitosan-graphene oxide (CS_GO) composite membranes containing different amounts of GO were prepared and used as sorbents for the SPE of pesticides. To improve their dimensional stability in aqueous medium, the CS_GO membranes were surface crosslinked with glutaraldehyde. The composite systems were characterized by Fourier transform infrared spectroscopy, scanning electron microscopy, thermogravimetric analysis, swelling degree, contact angle, and mechanical measurements. As the GO content increased, a decrease in surface homogeneity, an improvement of mechanical properties, and a reduction of thermal stability of the CS-based membranes were observed. The increased dimensional stability in water, together with the presence of high GO amounts, made the prepared composite membranes more efficacious than the ones based just on CS in isolating and preconcentrating different hydrophilic/hydrophobic pollutants.


Assuntos
Quitosana/química , Grafite/química , Membranas Artificiais , Praguicidas/isolamento & purificação , Extração em Fase Sólida/instrumentação , Poluentes Químicos da Água/isolamento & purificação , Cromatografia Líquida de Alta Pressão , Praguicidas/análise , Extração em Fase Sólida/métodos , Espectrometria de Massas em Tandem , Água/análise , Poluentes Químicos da Água/análise
6.
Sensors (Basel) ; 21(16)2021 Aug 09.
Artigo em Inglês | MEDLINE | ID: mdl-34450826

RESUMO

Precise and quick estimates of soil moisture content for the purpose of irrigation scheduling are fundamentally important. They can be accomplished through the continuous monitoring of moisture content in the root zone area, which can be accomplished through automatic soil moisture sensors. Commercial soil moisture sensors are still expensive to be used by famers, particularly in developing countries, such as Egypt. This research aimed to design and calibrate a locally manufactured low-cost soil moisture sensor attached to a smart monitoring unit operated by Solar Photo Voltaic Cells (SPVC). The designed sensor was evaluated on clay textured soils in both lab and controlled greenhouse environments. The calibration results demonstrated a strong correlation between sensor readings and soil volumetric water content (θV). Higher soil moisture content was associated with decreased sensor output voltage with an average determination coefficient (R2) of 0.967 and a root-mean-square error (RMSE) of 0.014. A sensor-to-sensor variability test was performed yielding a 0.045 coefficient of variation. The results obtained from the real conditions demonstrated that the monitoring system for real-time sensing of soil moisture and environmental conditions inside the greenhouse could be a robust, accurate, and cost-effective tool for irrigation management.


Assuntos
Solo , Água , Água/análise
7.
Molecules ; 26(15)2021 Jul 28.
Artigo em Inglês | MEDLINE | ID: mdl-34361713

RESUMO

The textural properties of butter are influenced by its fat content and implicitly by the fatty acids composition. The impact of butter's chemical composition variation was studied in accordance with texture and color properties. From 37 fatty acids examined, only 18 were quantified in the analyzed butter fat samples, and approximately 69.120% were saturated, 25.482% were monounsaturated, and 5.301% were polyunsaturated. The butter samples' viscosity ranged between 0.24 and 2.12 N, while the adhesiveness ranged between 0.286 to 18.19 N·mm. The principal component analysis (PCA) separated the butter samples based on texture parameters, fatty acids concentration, and fat content, which were in contrast with water content. Of the measured color parameters, the yellowness b* color parameter is a relevant indicator that differentiated the analyzed sample into seven statistical groups; the ANOVA statistics highlighted this difference at a level of p < 0.001.


Assuntos
Manteiga/análise , Ácidos Graxos Insaturados/química , Ácidos Graxos/química , Água/análise , Animais , Cor , Ácidos Graxos/classificação , Ácidos Graxos/isolamento & purificação , Ácidos Graxos Insaturados/classificação , Ácidos Graxos Insaturados/isolamento & purificação , Análise de Alimentos/métodos , Humanos , Análise de Componente Principal , Paladar/fisiologia , Viscosidade
8.
Molecules ; 26(16)2021 Aug 04.
Artigo em Inglês | MEDLINE | ID: mdl-34443311

RESUMO

The aim of this work is to develop an industrially suitable process for the sustainable waste disposal in wine production. The proposed process involves the development of an environmentally friendly method for the isolation of biologically active compounds from Grasevina grape pomace according to the green extraction principles, in order to obtain a ready-to-use extract. In this process, deep eutectic solvents (DES) were used as extraction solvents. Aiming to save time in selecting the optimal DES that would provide the most efficient Grasevina pomace polyphenols extraction, the user-friendly software COSMOtherm was used and 45 DES were screened. Moreover, the prepared extracts were chemically and biologically characterized to confirm their safety for human application. Computational and experimental results proved the applicability of COSMOtherm in the selection of the optimal DES for the environmentally friendly preparation of the ready-to-use extract from Grasevina grape pomace with expected application in the cosmetic industry.


Assuntos
Software , Solventes/química , Vitis/química , Resíduos/análise , Catequina/análise , Sobrevivência Celular/efeitos dos fármacos , Células HaCaT/efeitos dos fármacos , Humanos , Extratos Vegetais/farmacologia , Polifenóis/isolamento & purificação , Água/análise
9.
Sensors (Basel) ; 21(15)2021 Jul 29.
Artigo em Inglês | MEDLINE | ID: mdl-34372375

RESUMO

The goal of this research is to use a WORKSWELL WIRIS AGRO R INFRARED CAMERA (WWARIC) to assess the crop water stress index (CWSIW) on tomato growth in two soil types. This normalized index (CWSI) can map water stress to prevent drought, mapping yield, and irrigation scheduling. The canopy temperature, air temperature, and vapor pressure deficit were measured and used to calculate the empirical value of the CWSI based on the Idso approach (CWSIIdso). The vegetation water content (VWC) was also measured at each growth stage of tomato growth. The research was conducted as a 2 × 4 factorial experiment arranged in a Completely Randomized Block Design. The treatments imposed were two soil types: sandy loam and silt loam, with four water stress treatment levels at 70-100% FC, 60-70% FC, 50-60% FC, and 40-50% FC on the growth of tomatoes to assess the water stress. The results revealed that CWSIIdso and CWSIW proved a strong correlation in estimating the crop water status at R2 above 0.60 at each growth stage in both soil types. The fruit expansion stage showed the highest correlation at R2 = 0.8363 in sandy loam and R2 = 0.7611 in silt loam. VWC and CWSIW showed a negative relationship with a strong correlation at all the growth stages with R2 values above 0.8 at p < 0.05 in both soil types. Similarly, the CWSIW and yield also showed a negative relationship and a strong correlation with R2 values above 0.95, which indicated that increasing the CWSIW had a negative effect on the yield. However, the total marketable yield ranged from 2.02 to 6.8 kg plant-1 in sandy loam soil and 1.75 to 5.4 kg plant-1 in silty loam soil from a low to high CWSIW. The highest mean marketable yield was obtained in sandy loam soil at 70-100% FC (0.0 < CWSIW ≤ 0.25), while the least-marketable yield was obtained in silty loam soil 40-50% FC (0.75 < CWSIW ≤ 1.0); hence, it is ideal for maintaining the crop water status between 0.0 < CWSIW ≤ 0.25 for the optimum yield. These experimental results proved that the WWARIC effectively assesses the crop water stress index (CWSIW) in tomatoes for mapping the yield and irrigation scheduling.


Assuntos
Lycopersicon esculentum , Desidratação , Solo , Temperatura , Água/análise
10.
Ecotoxicol Environ Saf ; 223: 112576, 2021 Oct 15.
Artigo em Inglês | MEDLINE | ID: mdl-34340150

RESUMO

Hydrogel polymers have been used to enhance water and nutrient retention in agricultural soils. The incorporation of nanoparticles to yield composite hydrogels has also gained substantial momentum over the years. The aim of the research was to investigate the effect of hydrogel-nano natural char composite (reinforced starch-based hydrogels with natural char nanoparticles) at three levels 0%, 0.3% and 0.6% (w/w) on nutritional and morphological responses of tomato plant (Lycopersicon esculentum Mill.) as well as on some soil biological properties under water-deficit stress at three levels 50% water-holding capacity (WHC) (severe stress), 75% WHC (mild stress), and 85% WHC (non-stress conditions). The different levels of nano-composite and water deficit stress significantly (P < 0.05) affected plant morpho-nutritional indices and soil microbial traits. Water-deficit stress decreased all measured parameters in this assay. However, the use of nanocomposite reduced the negative effects of water-deficit stress on tomato growth and development. The magnitude of the responses to the nanocomposite treatment depended on the concentration of applied nanocomposite and stress severity with the most positive effects on the growth (22-45% increase) and nutritional indices (P, Fe, and Zn concentration) (16-29% increase) of tomato at level 0.3% hydrogel nanocomposite and 85% WHC and on soil respiration rate (61% increase) and microbial population size ( 89% increase) at the level 0.6% hydrogel nanocomposite and 75% WHC. Accordingly, it is suggested that the application of hydrogel-nano natural char composite as a promising soil amendment, if used correctly, can be a successful method to maintain soil moisture content (improved tomato growth), plant nutrients, and soil microbial activity in the tomato growing medium.


Assuntos
Lycopersicon esculentum , Nanopartículas , Hidrogéis , Solo , Água/análise
11.
Ying Yong Sheng Tai Xue Bao ; 32(6): 2079-2088, 2021 Jun.
Artigo em Chinês | MEDLINE | ID: mdl-34212614

RESUMO

The sandy-hilly region of northwest Shanxi is a typical fragile agro-pastoral ecotone in north China. With the artificial Caragana korshinskii at 0 (the uncultivated land), 6, 12, 18, 40 and 50 years-old in the typical sandy-hilly region of northwest Shanxi as the subjects, we investigated soil moisture, aboveground and belowground biomass, individual morphological characteristics, growth, reproduction, and photosynthetic physiological characteristics of different-aged C. korshinskii, with the aim to evaluate the long-term growth and reproductive dynamic characteristics of artificial C. korshinskii. The results showed that soil moisture was significantly affected by stand ages. Soil moisture was low under the 6-year-old C. korshinskii plantation. During 6-18 years-old, soil moisture increased due to the increased crown width and reduced the near-surface wind speed, solar radiation, and soil water evaporation. During 18-50 years-old, soil moisture decreased sharply due to higher biomass and plant transpiration of C. korshinskii, and soil moisture was reduced to the lowest level of 11.1%. C. korshinskii mainly developed underground root system during 6-18 years-old, and changed to the aboveground biomass accumulation in 18-40 years-old. At the 40-year-old stand, biomass reached to the highest level with the greatest crown width and plant height. During 40-50 years-old, crown width and plant height decreased significantly, while the growth began to degrade. Photosynthetic capacity (chlorophyll a, b, carotenoid and total chlorophyll content) gra-dually decreased with the increases of planting ages, especially after 18 years-old. The quantity and quality of C. korshinskii seeds increased from 6 to 40 years-old, reached the maximum at 40 years-old stand, and began to decrease after 50 years-old. In the later growth period (30-40 years-old), more seeds with small individual weight were produced compared with early period (6-12 years-old). The germination test showed that small seeds had higher germination rate than the large ones under the same stand age, suggesting a shift of reproduction strategy. After 50 years-old, both of the growth and reproduction of C. korshinskii degenerated, and the plantation began to degrade.


Assuntos
Caragana , China , Clorofila A , Reprodução , Solo , Água/análise
12.
Sci Total Environ ; 794: 148704, 2021 Nov 10.
Artigo em Inglês | MEDLINE | ID: mdl-34218153

RESUMO

Local natural resources, (e.g., precipitation, solar radiation) are important for developing environmentally and scientifically sound management practices in dryland agroecosystem. Maximizing water use efficiency (WUE) in dryland farming systems remains a challenge. The objectives of this study were to assessing the robustness of radiation use efficiency (RUE) during different periods and investigate the interaction between RUE and WUE from water loss pattern and canopy development during wheat growth under different agricultural practices (non-mulched control, CK; transparent film mulching, TF; and black film mulching, BF) from 2013 to 2016 on the Loess Plateau, Northwest China. Results showed that RUE was mainly improved during post-anthesis under PM treatments. PM treatments contributed to elevated canopy photosynthesis and a delayed RUE peak during the reproductive period. Due to the increased spike number and ratio of plant transpiration to soil evaporation, TF and BF treatments had relatively stable photosynthetic activity relative to the CK treatment even those during dry periods. Initially, no relationship was found between WUE and RUE under the CK treatment. On the other hand, RUE and WUE were positively related in TF and BF treatments following a power function. RUE values increased with WUE rapidly to stabilize at a plateau value of 5.5 g MJ-1 under TF and BF treatments, and thus, the wheat WUE had a higher improvement potential than RUE as it did not have an apparent plateau value. PM treatments enhanced the wheat production by taking full advantage of local solar radiation and precipitation (improving RUE and WUE). This higher use efficiency of resources produced more photoassimilates for wheat than that under the CK management, increased source size (LAI) and sink size (spike number) during wheat growth seasons, and thus increased the final grain yield.


Assuntos
Triticum , Água , Plásticos , Estações do Ano , Solo , Água/análise
13.
Sci Total Environ ; 795: 148886, 2021 Nov 15.
Artigo em Inglês | MEDLINE | ID: mdl-34247077

RESUMO

Plastic film mulching has been extensively used for spring maize (Zea mays L.) production in the Hetao Irrigation District (HID). Determining whether transparent plastic film mulching results in premature senescence and yield reduction of spring maize still needs to be verified. A two-year field experiment was conducted in the HID that involved planting spring maize under three mulching practices on a flat plot 1) without mulching (control treatment, CK), 2) with black plastic film mulching (BM), 3) with transparent plastic film mulching (TM). The results indicated that TM and BM were superior to CK in terms of effects on soil hydrothermal conditions. Compared with BM, TM produced significantly higher soil temperature at V6, and had no significant temperature effect at V12, R1, R3, and R6. Both TM and BM promoted early seedling emergence and earlier silking, and TM extended the duration of the reproductive stages by 1-2 days compared with BM, and 4-5 days longer than CK. TM and BM produced greater kernel weights and kernel volumes in the superior and middle portions of the ear than CK. TM produced significantly greater total kernel weights per ear than BM at and after 23 days after silking. TM significantly increased grain-filling rate and length of the active grain-filling period compared with BM and CK. Additionally, TM and BM produced significantly higher photosynthetic parameters than CK at the grain-filling stage in the two study years. The net photosynthesis rate for TM was significantly greater than for BM. TM and BM significantly increased grain yields by 28.1% and 15.1%, respectively, in 2019 over CK, and by 24.6% and 21.1% in 2020. Transparent plastic film mulching could serve as a promising adaptive management practice to increase resource use efficiency and to improve maize productivity in the HID.


Assuntos
Plásticos , Solo , Agricultura , China , Água/análise , Zea mays
14.
Front Public Health ; 9: 620700, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-34211949

RESUMO

Many people in the world lack safe basic drinking water sources and rely on untreated water source. Packaged water can be considered as an alternative to other water sources if measures are put in place to ensure its safety for consumption. This study aimed to assess the bacteriological quality and heavy metal analysis of packaged water produced in Lusaka, Zambia and associated quality control measures. A cross-sectional study was conducted in May 2019 where 18 brands of packaged water were analyzed for total and fecal coliforms as well as concentrations of Lead, Chromium, and Cadmium. The study found that 33.5% of the packaged water produced in Lusaka did not comply with the standard for drinking water on bacteriological quality. We also found that the concentrations for Lead were <0.01 mg/l in all the 17 samples, thus compliant to WHO/ZABS standards. Concentrations of Chromium were between 0.002 and 0.62 mg/l and compliance to the standard was 11.8%. Concentrations for Cadmium were between 0.009 and 0.2 mg/l against the acceptable concentration of <0.003 mg/l. Most brands of the packaged water did not conform to the standards for drinking water.


Assuntos
Metais Pesados , Água , Estudos Transversais , Humanos , Metais Pesados/análise , Controle de Qualidade , Água/análise , Microbiologia da Água , Zâmbia
15.
Molecules ; 26(13)2021 Jun 22.
Artigo em Inglês | MEDLINE | ID: mdl-34206584

RESUMO

In this work, a simple and rapid method based on the lateral flow assay (LFA) has been developed for the detection of dual antibiotics. To achieve the quantitative assay and to reduce the non-specific adsorption, an internal system has been developed. A non-specific DNA was exploited as an internal standard and could be recognized by the DNA marker that was coated at the internal line. Two different kinds of aptamers were applied to recognize ampicillin (AMP) and kanamycin (KAM), and the distance between the detection line and conjugate pad was then optimized. Under the optimum conditions, the quantitative assays of AMP (R2 = 0.984) and KAM (R2 = 0.990) were achieved with dynamic ranges of 0.50 to 500.0 ng/L, and of 0.50 to 1000.0 ng/L, respectively. The LOQs of AMP and KAM were 0.06 ng/L and 0.015 ng/L, respectively. Finally, the proposed method has been successfully applied to analyze aquaculture water, tap water, and lake water, and hospital wastewater, indicating the established method could be used to monitor the environment.


Assuntos
Ampicilina/análise , Aptâmeros de Nucleotídeos/química , Canamicina/análise , Água/análise
16.
Ying Yong Sheng Tai Xue Bao ; 32(7): 2347-2354, 2021 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-34313051

RESUMO

The complex terrain and poor climatic conditions in Bashang area of Hebei Province result in water and soil loss and geological disasters, which pose a serious threat to ecological safety in North China. In order to improve local environmental quality, barren-resistant and fast-growing tree species such as Pinus sylvestris var. mongolica and Larix gmelinii are planted with large areas. However, unreasonable plantation density will lead to inefficient utilization of rainfall and intensify the conflict between forest and water. In this study, we analyzed the effects of five thinning intensities (0, 20%, 40%, 60%, 80%) of P. sylvestris var. mongolica plantation on herbs, litter, soil and overall water-holding capacity, with the aim to provide scientific basis for management of P. sylvestris var. mongolica. The results showed that water-holding rate of herb varied from 47.7% to 90.7%, and that the water-holding capacity of herb decreased with increasing thinning intensity. When the thinning intensity was less than 40%, water-holding capacity decreased slowly, and then decreased rapidly. With the increase of thinning intensity, natural water-holding rate and maximum water-holding rate of undecomposed layer and semi-decomposed layer decreased gradually, with the effective water-holding rate being 60%>40%>20%>80%>0, and the water-holding capacity of semi-decomposed layer being better than that of undecomposed layer. The water-holding capacity of soil decreased gradually with the increases of thinning intensity. Thinning intensity less than 40% promoted water holding capacity. Under different thinning intensities, the total water-holding rate of understory was 8.3%-14.3%, with an order of 20%>0>40%>60%>80%. In view of understory all layers and overall changes, the thinning intensity at 20% in the study area could effectively improve the understory water-holding capacity and achieve better ecological benefits.


Assuntos
Pinus sylvestris , Pinus , China , Florestas , Solo , Água/análise
17.
Ying Yong Sheng Tai Xue Bao ; 32(7): 2397-2406, 2021 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-34313057

RESUMO

To clarify the effects of alternation of drying and wetting on the formation of soil preferential flow in arid valley, taking the wasteland in the arid valley of Honghe River as the research object, we analyzed the soil preferential flow characteristics before and after the simulation of drying and wetting alternation based on dyeing tracer method, water breakthrough curve, and image processing technology. The results showed that, under the simulated alternation of drying and wetting, the matrix flow occurred in the 0-10 cm soil layer, the dyeing depth reached 35 cm, the horizontal width of the preferred path was only 3-10 cm, and the dyeing area curve fluctuated little. Simulated alternation of drying and wetting led to significant increases in the steady effluent, macropores number, and macroporosity. In the 0-20 cm soil layer, the steady effluent after alternation of drying and wetting was about 0.27 cm3·s-1 higher than that non-alternation of drying and wetting, macropores number in dyeing area was about 1.4 times higher, and the macroporosity was 13.4% higher. The macropores number was positively correlated with stable flow rate. After simulated alternation of drying and wetting, the number of macropores from large to small was 0.6-0.8 mm>0.8-1.0 mm>1.0-1.5 mm>1.5-2.0 mm>2.0-3.7 mm, while under non-alternation of drying and wetting, it was 0.8-1.0 mm>0.6-0.8 mm>1.0-1.5 mm>2.0-3.7 mm>1.5-2.0 mm. The macropores number in each pore size range was significantly correlated with the dyeing area ratio. After simulated alternation of drying and wetting, the correlation increased, and the dominant factor affecting the occurrence of preferential flow changed from the macropores number in the pore size range of 1.5-2.0 mm to that of 0.8-1.0 mm. Therefore, the alternation of drying and wetting would affect the characteristics of macropores, which caused the soil to be more prone to preferential flow and with higher magnitude.


Assuntos
Solo , Movimentos da Água , Dessecação , Rios , Água/análise
18.
Int J Biol Macromol ; 184: 804-811, 2021 Aug 01.
Artigo em Inglês | MEDLINE | ID: mdl-34175338

RESUMO

This study explored how microwave reheating (to about 73 °C at different power levels) affects the microstructure and digestion characteristics of cooked rice with different water contents (1.1 and 1.5 times that of rice in weight). Irrespective of water content, mainly the V-type crystallites remained after microwaving reheating, with slight changes in other multi-scale structural features. Only at a relatively high water content (1.5) and with a power level high enough could short-range order be reduced. Such microwave reheating increased the digestion resistance of cooked rice. At a water content of 1.1 times, increasing the microwave power led to a decreased rapid digestible starch (RDS) content and an increased resistant starch (RS) content. With a higher water content (1.5), the enhancement of digestion resistance with higher microwave power was less significant but still, a reduced slowly digestible starch (SDS) content and a higher RS content were observed.


Assuntos
Oryza/química , Amido Resistente/análise , Água/análise , Culinária , Temperatura Alta , Microscopia Eletrônica de Varredura , Micro-Ondas , Espectroscopia de Infravermelho com Transformada de Fourier , Difração de Raios X
19.
J Dairy Sci ; 104(9): 9607-9616, 2021 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-34176627

RESUMO

Salmonella persistence in milk powders has caused several multistate foodborne disease outbreaks. Therefore, ways to deliver effective thermal treatment need to be identified and validated to ensure the microbial safety of milk powders. In this study, a process of hot air-assisted radio frequency (HARF) followed by holding at high temperatures in a convective oven was developed for pasteurization of milk powders. Heating times were compared between HARF and a convection oven for heating milk powders to a pasteurization temperature, and HARF has been shown to considerably reduce the come-up time. Whole milk powder (WMP) and nonfat dry milk (NFDM) were inoculated with a 5-serotype Salmonella cocktail and equilibrated to a water activity of 0.10 to simulate the worst case for the microbial challenge study. After heating the sample to 95°C using HARF, followed by 10 and 15 min of holding in the oven, more than 5 log reduction of Salmonella was achieved in WMP and NFDM. This study validated a HARF-assisted thermal process for pasteurization of milk powder based on previously collected microbial inactivation kinetics data and provides valuable insights to process developers to ensure microbial safety of milk powder. This HARF process may be implemented in the dairy industry to enhance the microbial safety of milk powders.


Assuntos
Leite , Pasteurização , Animais , Contagem de Colônia Microbiana/veterinária , Microbiologia de Alimentos , Calefação , Temperatura Alta , Leite/química , Pós , Água/análise
20.
Sci Total Environ ; 792: 148290, 2021 Oct 20.
Artigo em Inglês | MEDLINE | ID: mdl-34153752

RESUMO

Understanding changes in ecosystem services and their drivers is important for effective riparian ecosystem conservation and restoration. In the study, changes in water-related ecosystem services (soil conservation, water purification, and water yield) from 2007 to 2015 in Liaohe River Reserve, China were analyzed using the Integrated Valuation of Ecosystem Services and Trade-offs model. Impacts of landscape patterns on ecosystem services for different stages of restoration, i.e., farmland abandonment and natural succession stages were determined by stepwise regression analysis, respectively. The results showed that landscape fragmentation, landscape diversity, farmland fragmentation and grassland aggregation increased at the farmland abandonment stage. Landscape aggregation and diversity increased, whereas farmland fragmentation and grassland fragmentation decreased at the natural succession stage. Water-related ecosystem services improved since farmland abandonment, but water yield decreased from 1.57 × 106 m3 to 1.47 × 106 m3 at natural succession stage from 2011 to 2015. Water yield dynamics both at farmland abandonment and natural restoration stages were not significantly associated with landscape metrics. Dynamics of soil retention and water purification services at the farmland abandonment stage were significantly affected by landscape patch numbers, farmland division, and grassland aggregation. Interspersion and juxtaposition between different patch types, farmland edge density, grassland division, and grassland aggregation played significant roles in the dynamics of soil retention and water purification services at the natural restoration stage. The results provide scientific guidance for riparian management at the landscape scale to better restore water-related ecosystem services.


Assuntos
Ecossistema , Rios , China , Solo , Água/análise
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