The adsorption potential of charcoal for the removal of heavy metal ions is well documented in the literature. However, its exploration for uptake of technologically valuable metal ions such as Sr2+ is poorly known. In this work, the batch adsorption study of Sr2+ ion from aqueous solution as well as from saline matrix (>3% of NaCl) onto charcoal has been carried out. The experiments were conducted with two charcoals, i.e., our prepared charcoal (coconut shell charcoal) and commercial charcoal. Strontium adsorption has been investigated as a function of its initial concentration, contact time, and varied mass of adsorbent. Equilibrium adsorption data were evaluated for Langmuir and Freundlich isotherm models. The adsorption capacities (mg/g) of Sr2+ present in the salt matrix onto coconut shell charcoal and commercial charcoal was found to be 18.4 and 22.2, respectively. Uptake of Sr2+ from subsoil brine onto coconut shell charcoal has been successfully demonstrated in this work. 相似文献
We report the synthesis, characterization, and application of [Zn(1,4‐benzenedicarboxylate)(H2O)2]n, Zn(1,4‐benzenedicarboxylate)0.99(NH2‐1,4‐benzenedicarboxylate)0.01(H2O)2]n, [Zn(1,4‐benzenedicarboxylate)0.95(NH2‐1,4‐benzenedicarboxylate)0.05(H2O)2]n, and [Zn(1,4‐benzenedicarboxylate)0.9(NH2‐1,4‐benzenedicarboxylate)0.1(H2O)2]n as sorbents for the extraction of multiclass pesticides from coconut palm. Liquid chromatography with ultraviolet diode array detection was used as the analysis technique, and the experiments were performed at one fortification level (0.1 μg/g). The recoveries were 47–67, 51–70, 58–72, and 64–76% for [Zn(1,4‐benzenedicarboxylate)(H2O)2]n, Zn(1,4‐benzenedicarboxylate)0.99(NH2‐1,4‐benzenedicarboxylate)0.01(H2O)2]n, [Zn(1,4‐benzenedicarboxylate)0.95(NH2‐1,4‐benzenedicarboxylate)0.05(H2O)2]n, and [Zn(1,4‐benzenelate)0.95(NH2‐1,4‐benzenedicarboxylate)0.05(H2O)2]n, and [Zn(1,4‐benzenedicarboxylate)0.9(NH2‐1,4‐benzenedicarboxylate)0.1(H2O)2]n, respectively, with relative standard deviation ranging from 1 to 7% (n = 3). Detection and quantification limits were 0.01–0.05 and 0.05–0.2 μg/g, respectively, for the different pesticides studied. The method developed was linear over the range tested (0.01–10.0 μg/g) with r 2 > 0.9991. A direct comparison of [Zn(1,4‐benzenedicarboxylate)0.9(NH2‐1,4‐benzenedicarboxylate)0.1(H2O)2]n with the commercially available neutral alumina showed that [Zn(1,4‐benzenedicarboxylate)0.9(NH2‐1,4‐benzenedicarboxylate)0.1(H2O)2]n was a similar extracting phase for the pesticides investigated. 相似文献
An in situ‐forming gel system comprised of diblock copolymer formed from polyethylene glycol (PEG) and polycaprolactone (PCL) {MPEG‐b‐(PCL‐ran‐PLLA)} could be used in controlled drug delivery for tissue remodeling. The purpose of this study is to demonstrate favorable vocal folds (VF) regeneration by using MPEG‐b‐(PCL‐ran‐PLLA) diblock copolymers (C97L3; CL/LA ratio 97:3) incorporating hepatocyte growth factor (HGF). Gradual release of HGF from C97L3 is detected and biochemical properties of released HGF are maintained. A scar is made with microscissors on both VFs in 32 rabbits, followed by injection of HGF‐only, C97L3‐only, or HGF‐C97L3 composite gel in the left side VF, while the right side VF is left untreated. In vivo fluorescence live imaging system demonstrates that C97L3 enables the sustained release of injected HGF in the scarred VF for 12 weeks. The histological analysis shows increased glycosaminoglycan including hyaluronic acid accumulation and decreased collagen deposition. Videokymographic analysis shows more favorable vibrations of HGF‐C97L3 treated VF mucosa, compared to other treatment groups. In conclusion, the controlled HGF release helps to regulate extracellular matrix synthesis, and leads to the eventual functional improvement of the scarred VF.
In this paper, an efficient method for solving nonlinear Stratonovich Volterra integral equations is proposed. By using Bernoulli polynomials and their stochastic operational matrix of integration, these equations can be reduced to the system of nonlinear algebraic equations with unknown Bernoulli coefficient which can be solved by numerical methods such as Newton’s method. Also, an error analysis is valid under fairly restrictive conditions. Furthermore, in order to show the accuracy and reliability of the proposed method, the new approach is compared with the block pulse functions method by some examples. The obtained results reveal that the proposed method is more accurate and efficient than the block pulse functions method. 相似文献
A waveguide occupies infinite strip with one or several narrows on a two-dimensional (2D) plane and is governed by the Helmholtz equation with Dirichlet boundary condition. On the waveguide continuous spectrum, which coincides with a half-axis, a scattering matrix is defined. At each point of the continuous spectrum this matrix has finite size, which changes at thresholds. The thresholds form a sequence of positive numbers increasing to infinity. Approximate calculation of the scattering matrix in a threshold vicinity requires special treatment. We discuss and compare two methods of numerical approximation to the scattering matrix near a threshold. 相似文献
A weighted (unweighted) graph is called equiarboreal if the sum of weights (the number) of spanning trees containing a given edge in is independent of the choice of edge. In this paper, we give some resistance characterizations of equiarboreal weighted and unweighted graphs, and obtain the necessary and sufficient conditions for -subdivision graphs, iterated double graphs, line graphs of regular graphs and duals of planar graphs to be equiarboreal. Applying these results, we obtain new infinite families of equiarboreal graphs, including iterated double graphs of 1-walk-regular graphs, line graphs of triangle-free 2-walk-regular graphs, and duals of equiarboreal planar graphs. 相似文献
This paper describes students’ perspectives of a one-off flipped lecture in a large undergraduate mathematics service course. The focus was on calculating matrix determinants and was designed specifically to introduce debate and argumentation into a mathematics lecture. The intention was to promote a deeper learning and understanding through engagement with the added hope of instilling some passion for the subject. During the lecture, students were asked to vote with their feet, literally moving around the lecture theatre to form groups according to their shared favourite technique for calculating matrix determinants. Group discussions were then followed by a whole class debate facilitated by the lecturers, before they wrapped up the lecture by resolving the professional disagreements that had come to light during the debate. Following the lecture, data on student perspectives was gathered using both surveys and focus groups. Within this paper, we share the data and reveal the interesting results that emerged from our analysis. Despite remaining unconvinced as to whether flipped lectures are better for learning, students reported greater engagement and increased understanding of the material covered. 相似文献
