The Determination of Lead by Electrothermal Atomic Absorption Spectrocsopy : A Study of the Molecular Interferences

The presence of interference effects in atomic absorption spectroscopy affects the degree of accuracy that can be obtained. A major source of interference in electrothermal atomization processes appears to involve the formation of molecular species. In the analysis of lead in the presence of chloride, three peaks are observed. The first of these peaks has an absorption spectrum characteristic of lead chloride. The second and third peaks cannot be identified on the basis of their respective spectra. In the presence of nitrate, the analysis of lead results in the presence of a broad band absorption profile that cannot be identified. The degree of molecular interference is dependent upon temperature, matrix concentration, graphite tube surface condition, the solution pH, and the wavelength used. An understanding of the factors which are actually causing the interferences to occur should lead to procedures for reducing or eliminating their effects. The most widely studied element in this respect is lead. However, the mechanisms involved in signal suppression or enhancement observed with varying matrices have not been elucidated. It is the purpose of this paper to further study interference effects on the analysis of various matrices for lead; in an attempt to gain a better understanding of the chemical and physical phenomena involved in atomization from the surface of a heated graphite furnace

Synthesis of polysulfone/polyamide thin film nanocomposite membranes for forward osmosis applications

Forward osmosis (FO) has attracted significant interest as a promising alternative to reverse osmosis (RO) in membrane-based water desalination applications. FO water flux, salt rejection and reverse solute flux are three critical parameters affecting membrane performance. Thin film composite (TFC) membranes have been widely used in FO processes. A typical TFC membrane consists of a rejection polyamide (PA) layer on top of a highly porous support layer. In the current study, carboxyl functionalized multi-walled carbon nanotubes (F-MWCNTs) were used as nano-fillers in the membrane rejection layer to enhance the FO membrane performance. Polyamide (PA) thin film nano-composite (TFNC) membranes were synthesized on top of polysulfone (PSF) porous support layers by interfacial polymerization (IP) using m-phenylenediamine (MPD) in water and trimesoyl chloride (TMC) in hexane. The PSF support layer was synthesized by phase inversion in a water bath of a casting solution of PSF and polvinylpyrrolidone (PVP) (pore forming agent) dissolved in anhydrous dimethyl formamide (DMF). Multi-walled carbon nanotubes were functionalized by oxidation in strong acidic solutions, and then incorporated in the MPD aqueous solution during IP. For the support layer, PSF and PVP concentrations were varied while monomers (MPD, TMC) concentrations, contact time and curing temperature were varied for the rejection layer. Experimental designs for both the support and the rejection layers were carried out using Design-Expert software including statistical analysis to identify the most significant factors affecting the membrane performance. The support layer of 18 wt% PSF and 2 wt% PVP was selected as the membrane support with the highest possible FO water flux and minimum reverse solute flux while the PA rejection layer of 4 wt/vol% MPD and 0.2 wt/vol% TMC was selected as the membrane rejection layer with a salt rejection of 88.30±0.11%. Finally, the amount of F-MWCNTs was varied from 0.01 to 0.2 wt/vol% to study their effect on the membrane morphology and performance. The synthesized membranes were characterized using Scanning Electron Microscopy (SEM), Atomic Force Microscopy (AFM), Fourier Transform Infrared Spectrophotometry (FTIR) and Brunauer-Emmett-Teller gas adsoprtion analysis (BET). FO performance was investigated using deionized water as the feed solution and 2 M NaCl as the draw solution. It was found that F-MWCNTs enhanced the membrane hydrophilicity and surface roughness that led to increased FO water flux. Most importantly, the salt rejection was also increased at low concentrations of F-MWCNTs (\u3c 0.05 wt/vol%). The membrane with 0.01 wt/vol% F-MWCNTs showed the highest salt rejection (90.05±0.25%) with a FO water flux of 50.23±0.93 L/m2 h and a reverse solute flux of 2.76±0.21 g/m2h, thus outperforming thin film composite FO membranes reported in literature

Effect of sex on meat quality characteristics

The goal of the current work was to determine the quality of male and female cattle and buffalo meat, as well as a trial for improving meat quality by feeding the experimental groups from cattle and buffalo for four months in rations containing 16.5% protein. During the year 2021, eighty samples of cattle and buffalo were obtained from butcher shops in Luxor, Egypt. The samples were divided into four categories: male cattle, female cattle, male buffalo, and female buffalo each class was represented by 20 samples. Trails for improvement of the nutritional content of meat by feeding ration containing 16.5% protein to male cattle and buffalo, each class was represented by 10 animals. The samples were analyzed for determination of moisture, protein, fat, ash, carbohydrate, energy percentage, cooking loss, water holding capacity, tenderness as well as cholesterol determined in perinephric fat. Male beef was characterized by greater protein content (18.02% ± 0.35%). On the other hand, male buffalo was characterized by low fat content and cholesterol levels of 1.60% ± 0.85% and 294.30 ± 2.40 mg/100gm, respectively. The experimental male cattle showed the highest protein percentage (18.50% ± 0.37%) and lowest cholesterol level (267.19 ± 6.25 mg /100 gm). The use of the experimental ration could improve the quality of male beef in terms of protein value as well as cholesterol level

Evaluating the Effects of the A-Double Vehicle Combinations If Introduced to a Line-Haul Freight Transport Network

One of the solutions to improve the eco-efficiency of road freight transport is to combine existing transport modules into Longer and/or Heavier Vehicles (LHVs). The scientific and industrial communities have paid increasing attention to an LHV, known as the A-double combination, consisting of a tractor, two 13.5-m semitrailers, and a dolly converter. The present research contributes to the existing literature by developing a methodology based on a cost-benefit approach to quantify the effects of the A-double combinations if introduced to a line-haul transport system. Four implementation scenarios and sensitivity analyses of main variables were evaluated within a case study of 48,472 line-haul trips in Denmark. The results indicate that in the least beneficial scenario, the A-double combinations reduce transport cost by 9.65% while reducing trips, CO2 emissions, and road wear by 17.91%, 5.34%, and 9.55%, respectively. Besides, the use of A-double combinations can significantly reduce empty tractor-semitrailer trips. However, the benefits are relatively less in the case of just-in-time deliveries and cargo constrained by vehicle weight. Also, cost saving is highly sensitive to driver salaries, fuel prices, and driving speeds. This research provides valuable insights into the potentials of A-double combinations under different regulations and freight characteristics from a micro perspective

Linking QTLs that Regulate the Distinct Epicuticular Layers in the Spike Glume, and Its Variable Composition to Improve Reproductive Stage Heat Tolerance in Wheat

Global climate experiments project an average increase of ambient temperatures of 0.2°C per decade. Such prediction emphasizes the importance of crop varieties that have high heat tolerance. Wheat is significantly affected by high temperature. Optimizing heat and drought tolerance in wheat is one way to improve breeding efficiency. Previous studies on wheat leaf epicuticular wax (EW) have shown a strong association between wax load and high temperature stress tolerance. This study aimed to investigate the relationship between EW on wheat glume and high temperature tolerance. This study also compared the effect of glume EW to the effect of leaf EW on the plant agronomic productivity. A recombinant inbred line (RIL) population derived from the heat tolerant Australian cultivar ‘Halberd’ which we have previously identified as having a unique genetic loci regulating spike cooling, was used in this experiment. The RIL mapping panel contains 180 lines derived from Halberd and a heat susceptible cultivar, Len. The population was grown at multiple field locations at Collage Station, Texas, Uvalde, Texas, and Obregon, Mexico for the growing seasons of 2013 and 2014. The EW of leaves and glumes were extracted using published methods (Richardson et al, 2007). An alpha lattice design with 180 recombinants and 2 replications was used in four different environments over 2 years. The EW samples were collected at 10DAP and leaf/spike temperatures were recorded at the same time. Spectral canopy reflectance was measured between 350–1100 nm range. Yield components were estimated after harvest. Spike temperature depression was measured. The 180 RIL and their parents were mapped using 90K SNPs markers to identify linkage groups or QTL for EW. A strong correlation was found between mean wax load for leaf and that for glume as function of mean high temperature recorded for 10DAP across the environments with R^2 = 0.6719 and R^2 = 0.8483 respectively . The maximum mean of leaf EW at OBR14 being 5.37 and that of CS13 was 2.51 mg/dm^2 , while the glume EW mean at OBR14 was 5.97 mg/dm^2 and CS13 was 2.38 mg/dm^2 . The EW mean was higher in glumes as compared to that of leaf for all locations except for CS13, which was considered a more optimum climate for wheat. A strong correlation between the two wax loads for UVL13 was observed with R^2 = 0.8285 and r=0.9195 significant at p≤ 0.001. A significant correlation also was observed for the two wax loads for OBR14 with R^2 = 0.0304 and r=0.1744 significant at p≤ 0.05. All yield and yield components data showed significant variation between the different growing locations. Correlation between WI was significant at p≤ 0.05 for most water status indices were associated with the glume wax with R^2 ranging from 0.274 to 0.2198, whereas there was no correlation between WI and leaf wax. The thermal index had negative correlation and was only significant with glume wax content with r = -0.5943 and significance level of P≤0.001. Spike temperature had a positive correlation with both leaf and glume wax content with an R^2 values of 0.078 and 0.1952 respectively. Two significant QTL for EW were detected on chromosome 5B. Leaf EW, QLWax.tam-5B, was on position 104.584 and explained 6.8% of the variation. Glume EW, QGWax.tam-5B, was located on position 102.098 and explained 6.6% of the variation

Influence of cellulase addition to dairy goat diets on digestion and fermentation, milk production and fatty acid content

Twenty four French Alpine goats (39 ± 2·0 kg) were individually housed in a completely randomized design and fed a basal diet containing 146 g crude protein and 356 g neutral detergent fibre (NDF)/kg in the absence (control – CTRL) or presence (CELL) of 2 ml of cellulase/kg dry matter intake (DMI) for 70 days, which included a 10-day adaptation period. The feed was offered three times daily at 07·00, 13·00 and 19·00 h, but the single daily dose of cellulase was only fed at 07·00 h. Goats were hand milked daily; milk production recorded and samples taken for compositional analysis. During the last 5 days of the experimental period, goats from each group were individually housed in stainless steel metabolic cages to enable separate and total collection of faeces and urine for nutrient digestibility and ruminal fermentation determinations. Goats fed CELL had greater DMI and greater digestibility of dry matter (DM), organic matter and NDF than CTRL goats. CELL goats had greater ruminal pH, concentration of acetic acid and concentration of propionic acid than CTRL goats. However, the concentration of ruminal butyric was lower in CELL goats compared with CTRL goats. CELL goats had greater milk yield, energy corrected milk, milk energy content, milk energy output and milk density than CTRL goats and the milk content for total solids, fat, protein and lactose were also greater for CELL goats than for the CTRL goats. The milk of CELL goats had greater palmitoleic acid, cis-10-heptadecanoic acid content and mono-saturated acids than the milk of CTRL goats and lower linoleic acid, linolenic acid contents and saturated fatty acids than the milk of CTRL goats. These results suggest that addition of 2 ml cellulase/kg DM of feed in the diet of lactating French Alpine goats elevated their milk production and improved its composition probably due to improved feed utilization.UAE