Simulated mobilization of metals from sediments in response to lake acidification     

Nabil Arafat  Jerome . Nriagu 《Water, air, and soil pollution》1986,31(3-4):991-998

The regeneratable forms of pollutant metals in lake sediments were estimated using different chemical extractants and the effects of lake acidification on the mobilization of such metal fractions studied in laboratory microcosm. The release of each metal was found to increase exponentially below a threshold pH value, which was about 4.0 for Cu, Ni, Zn, Cd and Fe. The data suggest that a large percentage of pollutant metals are mobile as determined by chemical extraction techniques and long-term release experiments.  相似文献   

Zinc and copper in some soils of Egypt as related to other soil properties     

F. Awad  S. Fuda  S. M. Arafat 《植物养料与土壤学杂志》1985,148(3):225-232

Total Zn in alluvial and calcareous soils (average 138 and 70 ppm respectively) was significantly related to their contents of CaCO₃ (negatively), O.M. and clay (positively). Extracting Zn by Na₂EDTA gave the highest values for both soil types. Total Cu contents varied widely from 26 to 111 ppm in alluvial and from 15 to 30 ppm in calcareous soils. They were negatively correlated with the CaCO₃ contents. The pot experiments showed that EDTA(NH₄)₂CO₃, Na₂EDTA and DTPA are reasonable extractants for available Zn from both soil types. DTPA was efficient for all soils investigated, while Na₂ EDTA and EDTA-citrate were specific for extracting Cu from calcareous soils.  相似文献   

Hunting or habitat degradation? Decline of primate populations in Udzungwa Mountains,Tanzania: An analysis of threats     

Francesco Rovero  Arafat S. Mtui  Amani S. Kitegile  Martin R. Nielsen 《Biological conservation》2012,146(1):89-96

Hunting and habitat degradation are universal threats to primates across the tropics, thus deciphering the relative impact of threats on population relative abundance is critical to predicting extinction risk and providing conservation recommendations. We studied diurnal primates over a period of nearly 6 years in the Udzungwa Mountains of Tanzania, a site of global importance for primate conservation. We assessed how population relative abundance of five species (of which two are endemic and IUCN-Endangered) differed between two forest blocks that are similar in size and habitat types but contrast strongly in protection level, and how abundance changed during 2004–2009. We also measured habitat and disturbance parameters and, in the unprotected forest, evaluated hunting practices. We found significant differences in primates’ abundance between protected and unprotected forests, with the greater contrast being the lower abundance of colobine monkeys (Udzungwa red colobus and Angolan colobus) in the unprotected forest. At this site moreover, colobines declined to near-extinction over the study period. In contrast, two cercopithecines (Sanje mangabey and Sykes’ monkey) showed slightly higher abundance in the unprotected forest and did not decline significantly. We argue that escalating hunting in the unprotected forest has specifically impacted the canopy-dwelling colobus monkeys, although habitat degradation may also have reduced their abundance. In contrast, cercopithecines did not seem affected by the current hunting, and their greater ecological adaptability may explain the relatively higher abundance in the unprotected forest. We provide recommendations towards the long-term protection of the area.  相似文献   

Detection of spinal ataxia in horses using fuzzy clustering of body position uncertainty     

Keegan KG  Arafat S  Skubic M  Wilson DA  Kramer J  Messer NM  Johnson PJ  O'Brien DP  Johnson G 《Equine veterinary journal》2004,36(8):712-717

REASONS FOR PERFORMING STUDY: Subjective neurological evaluation in horses is prone to bias. An objective method of spinal ataxia detection is not subject to these limitations and could be of use in equine practice and research. HYPOTHESIS: Kinematic data in the walking horse can differentiate normal and spinal ataxic horses. METHODS: Twelve normal and 12 spinal ataxic horses were evaluated by kinematic analysis walking on a treadmill. Each body position signal was reduced to a scalar measure of uncertainty then fuzzy clustered into normal or ataxic groups. Correct classification percentage (CCP) was then calculated using membership values of each horse in the 2 groups. Subsequently, a guided search for measure combinations with high CCP was performed. RESULTS: Eight measures of body position resulted in CCP > or = 70%. Several combinations of 4-5 measures resulted in 100% CCP. All combinations with 100% CCP could be obtained with one body marker on the back measuring vertical and horizontal movement and one body marker each on the right fore- and hindlimb measuring vertical movement. CONCLUSIONS AND POTENTIAL RELEVANCE: Kinematic gait analysis using simple body marker combinations can be used objectively to detect spinal ataxia in horses.  相似文献   

Biochemical and molecular investigation of oxidative stress associated with urolithiasis induced by increased dietary calcium or protein in chickens     

Mahmoud G. El Sebaei  Nagah Arafat  Reham A. El-Shafei  Mohamed A. El-Adl  Amany Farag  Abeer E. Aziza  Abdelfattah H. Eladl 《Journal of animal physiology and animal nutrition》2021,105(1):129-139

This study was carried out to evaluate the effects of induced urolithiasis by high dietary calcium (Ca) or protein levels on biochemical analyte levels, redox status, selected inflammatory cytokines and histopathology in chickens. A total of 90 one-day-old white Hy-Line chicks were fed basal control diets containing 20% crude protein (CP) and 1% Ca until they reached 44 days of age. After that, the birds were divided into three groups (30 birds per group). All management factors (light, temperature, ventilation, stock density and diet) were identical among the three groups throughout the study except for the dietary Ca and protein percentages. Group I was fed a control diet containing 20% CP and 1% Ca, group II was fed a high-Ca diet containing 5% Ca, and group III was fed a high-protein diet containing 25% CP. Our findings clearly demonstrated that dietary imbalance (caused by high-Ca or high-CP levels) per se in chickens was physiologically harmful, as it was accompanied by post-mortem lesions; biochemical, redox status and histopathological alterations; and upregulation of inflammatory cytokines (interleukin (IL)-1β and IL-6). In particular, the birds fed the high-Ca diet clearly exhibited the most obvious alterations in most of the endpoints. In conclusion, this study constitutes the first extensive investigation of the effects of high-Ca or high-protein diets induced urolithiasis on growth performance, redox status, inflammatory cytokine levels and pathological characterization in chickens.  相似文献   

Bioadhesive Controlled Metronidazole Release Matrix Based on Chitosan and Xanthan Gum     

Ala’a F. Eftaiha  Nidal Qinna  Iyad S. Rashid  Mayyas M. Al Remawi  Munther R. Al Shami  Tawfiq A. Arafat  Adnan A. Badwan 《Marine drugs》2010,8(5):1716-1730

Metronidazole, a common antibacterial drug, was incorporated into a hydrophilic polymer matrix composed of chitosan xanthan gum mixture. Hydrogel formation of this binary chitosan-xanthan gum combination was tested for its ability to control the release of metronidazole as a drug model. This preparation (MZ-CR) was characterized by in vitro, ex vivo bioadhesion and in vivo bioavailability study. For comparison purposes a commercial extended release formulation of metronidazole (CMZ) was used as a reference. The in vitro drug-release profiles of metronidazole preparation and CMZ were similar in 0.1 M HCl and phosphate buffer pH 6.8. Moreover, metronidazole preparation and CMZ showed a similar detachment force to sheep stomach mucosa, while the bioadhesion of the metronidazole preparation was higher three times than CMZ to sheep duodenum. The results of in vivo study indicated that the absorption of metronidazole from the preparation was faster than that of CMZ. Also, MZ-CR leads to higher metronidazole C_max and AUC relative to that of the CMZ. This increase in bioavailability might be explained by the bioadhesion of the preparation at the upper part of the small intestine that could result in an increase in the overall intestinal transit time. As a conclusion, formulating chitosan-xanthan gum mixture as a hydrophilic polymer matrix resulted in a superior pharmacokinetic parameters translated by better rate and extent of absorption of metronidazole.  相似文献   

Preparation of Chito-Oligomers by Hydrolysis of Chitosan in the Presence of Zeolite as Adsorbent     

Khalid A. Ibrahim  Bassam I. El-Eswed  Khaleel A. Abu-Sbeih  Tawfeeq A. Arafat  Mahmoud M. H. Al Omari  Fouad H. Darras  Adnan A. Badwan 《Marine drugs》2016,14(8)

An increasing interest has recently been shown to use chitin/chitosan oligomers (chito-oligomers) in medicine and food fields because they are not only water-soluble, nontoxic, and biocompatible materials, but they also exhibit numerous biological properties, including antibacterial, antifungal, and antitumor activities, as well as immuno-enhancing effects on animals. Conventional depolymerization methods of chitosan to chito-oligomers are either chemical by acid-hydrolysis under harsh conditions or by enzymatic degradation. In this work, hydrolysis of chitosan to chito-oligomers has been achieved by applying adsorption-separation technique using diluted HCl in the presence of different types of zeolite as adsorbents. The chito-oligomers were retrieved from adsorbents and characterized by differential scanning calorimetry (DSC), liquid chromatography/mass spectroscopy (LC/MS), and ninhydrin test.  相似文献   

Evaluating the Effects of Biochar and SAP Polymer on Soil Physical Quality Indices     

Arafat Alkhasha 《Communications in Soil Science and Plant Analysis》2020,51(8):1123-1135

ABSTRACT

The aim of this study was to examine the effects of soil amendments to sandy loam and soil physical indices, mainly soil aggregates, soil retention curve, and pore size distribution. Date palm waste biochar at rates 2% (B₁), 4% (B₂), 6% (B₃), and 8% (B₄) and sorbent adsorption polymer (SAP) at rates 0.2% (P₁), 0.4% (P₂), 0.6% (P₃), and 0.8% (P₄) (w/w). In addition, the combination of both as B₁:P₁, B2:P₂, B₃:P₃, and B₄:P₄, were added to the soil as amelioration materials. The results revealed that on the average, soil water content increased by 7.3%, 3.3%, and 15.0% with the addition of biochar, polymer, and the combination, respectively. The location parameters d_mode, d_median, and d_mean decreased by 6.4%, 8.8%, and 10.6% for the biochar, and increased by 2.3%, 4.6%, and 3.4% for the polymer treatments, decreased by 4.8%, 4.4%, and 4.2% for the combination treatments, respectively. Shape parameters such as standard deviation (SD), (spread) skewness (asymmetry), and kurtosis (peakedness) were 2.2, – 0.27, and 1.6 for the biochar treatments, 2.17, – 0.27, and 1.6 for the polymer treatments, and 2.17, – 0.23, and 1.6, for the combination treatments, respectively. The aggregate stability (SA) of soils of size 0.25 and 0.13 mm increased by 50.8% and 50% with the application of biochar (B₂ = 4%) and polymer (P₂ = 0.4%) B₂:P₂ and polymer (P₄ = 0.8%) P₄ treatments, respectively. This study recommends using combination of biochar with polymer treatments on sandy loam soil in arid area due to its strong hydro-physical properties.  相似文献   

Detection of lameness and determination of the affected forelimb in horses by use of continuous wavelet transformation and neural network classification of kinematic data     

Keegan KG  Arafat S  Skubic M  Wilson DA  Kramer J 《American journal of veterinary research》2003,64(11):1376-1381

OBJECTIVE: To investigate continuous wavelet transformation and neural network classification of gait data for detecting forelimb lameness in horses. ANIMALS: 12 adult horses with mild forelimb lameness. PROCEDURE: Position of the head and right forelimb foot, metacarpophalangeal (ie, fetlock), carpal, and elbow joints was determined by use of kinematic analysis before and after palmar digital nerve blocks. We obtained 8 recordings from horses without lameness, 8 with right forelimb lameness, and 8 with left forelimb lameness. Vertical and horizontal position of the head and vertical position of the foot, fetlock, carpal, and elbow joints were processed by continuous wavelet transformation. Feature vectors were created from the transformed signals and a neural network trained with data from 6 horses, which was then tested on the remaining 2 horses for each category until each horse was used twice for training and testing. Correct classification percentage (CCP) was calculated for each combination of gait signals tested. RESULTS: Wavelet-transformed vertical position of the head and right forelimb foot had greater CCP (85%) than untransformed data (21%). Adding data from the fetlock, carpal, or elbow joints did not improve CCP over that for the head and foot alone. CONCLUSIONS AND CLINICAL RELEVANCE: Wavelet transformation of gait data extracts information that is important for the detection and differentiation of forelimb lameness of horses. All of the necessary information to detect lameness and differentiate the side of lameness can be obtained by observation of vertical head movement in concert with movement of the foot of 1 forelimb.  相似文献   

Effect of arbuscular mycorrhizal fungi on growth,mineral nutrition,antioxidant enzymes activity and fruit yield of tomato grown under salinity stress   总被引：1，自引：0，他引：1  

Arafat Abdel Hamed Abdel Latef  He Chaoxing 《Scientia Horticulturae》2011

The purpose of this study was to investigate the mechanisms underlying alleviation of salt stress by arbuscular mycorrhizal fungi Glomus mosseae. Tomato (Lycopersicon esculentum L. cv. Zhongzha105) plants were cultivated in soil with 0, 50 and 100 mM NaCl. Mycorrhization alleviated salt induced reduction of root colonization, growth, leaf area, chlorophyll content, fruit fresh weight and fruit yield. The concentrations of P and K were higher in AM compared with nonAM plants grown under nonsaline and saline conditions. Na concentration was lower in AM than nonAM plants grown under nonsaline and saline conditions. AMF colonization was accompanied by an enhancement of activity of superoxide dismutase (SOD), catalase (CAT), peroxidase (POD) and ascorbate peroxidase (APX) in leaves of both salt-affected and control plants. In addition, inoculation with AMF caused reduction in MDA content in comparison to salinized plants, indicating lower oxidative damage in the colonized plants.  相似文献