Sequential treatment for landfill leachate by applying coagulation-adsorption process

mohammad J. K. bashir,Tay Ming Xian,Areeb Shehzad,Sumathi Sethupahi,Ng Choon Aun,Salem Abu Amr 한국자원공학회 2017 Geosystem engineering Vol.20 No.1

Landfill leachate has always been the most problematic factor in municipal solid waste management. Leachate generated from landfills generally contains high amount of organic and inorganic compounds that might cause pollution to water resources. In the current study, sequential treatment of landfill leachate using coagulation–flocculations a pretreatment process followed by adsorption process was used to treat chemical oxygen demand (COD), ammonical nitrogen (NH3-N) and color from raw landfill leachate. Coagulation–flocculation process was examined using alum and ferric chloride. The optimum working pH for the tested coagulants was 5 and FeCl3 showed higher removal efficiency for landfill leachate than alum. The pretreated leachate was further treated via two types of adsorbents i.e., powdered activated carbon (PAC) and zeolite. The optimum experimental conditions for PAC and zeolite adsorptions were found to be 40 g/L at 30 min and 80 g/L at 120 min, respectively. Scanning electron microscope and Fourier transform infrared spectroscopy tests were conducted to examine the surface morphology and chemical properties of the adsorbents. The results showed that the Freundlich isotherm was best fitted for PAC adsorption while Langmuir isotherm model showed good conformity for zeolite adsorption. Besides, pseudo-second order model was found to be the best fitted kinetic model for both PAC and zeolite adsorption where the R2 was closed to unity for all parameters. On balance, FeCl3 coagulation-PAC adsorption has shown higher removal efficiency for color, COD, and NH3-N as compared to FeCl3 coagulation-zeolite adsorption.

On the bounds of the eigenvalues of matrix polynomials

Wali Mohammad Shah,Zahid Bashir Monga 강원경기수학회 2023 한국수학논문집 Vol.31 No.2

Let $P(z):=\displaystyle{\sum\limits_{j=0}^n} A_jz^j,~A_j\in \mathbb{C}^{m\times m}, 0\leq j\leq n$ be a matrix polynomial of degree $n,$ such that $$A_n\geq A_{n-1}\geq \ldots \geq A_0\geq 0,~A_n>0.$$ Then the eigenvalues of $P(z)$ lie in the closed unit disk. This theorem proved by Dirr and Wimmer [IEEE Trans. Automat. Control \textbf{52}(2007), 2151-2153 ] is infact a matrix extension of a famous and elegant result on the distribution of zeros of polynomials known as Enestr\"om-Kakeya theorem. In this paper, we prove a more general result which inter alia includes the above result as a special case. We also prove an improvement of a result due to L\^{e}, Du, Nguy\^{e}n [Oper. Matrices, \textbf{13}(2019), 937-954] besides a matrix extention of a result proved by Mohammad [Amer. Math. Monthly, vol.74, No.3, March 1967].

Numerical fluid structural interface analysis in condenser microphone design

Akbar Ranjbar,Mohammad-Ali Saeimi-Sadigh,Bashir Behjat 대한기계학회 2011 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.25 No.3

Condenser microphones are widely used in electronic and acoustic applications. Although, various mechanical and electro-mechanical methods have been developed to design and analyze these sensors. However, due to the difficulty of fluid-structural-electrical couplings,none of them can introduce a method that consider all parameters of the design together. This research concerns the effects of four main parameters: a) Air gap size; b) Number of holes on the back-plate; c) holes radius size and d) location of the holes in back plate, on the response of the microphones. This analysis have been carried out based on coupled finite element and finite volume method using ANSYS-CFX software to simulate fluid-structure interaction between the diaphragm and air in the air-gap region. By using this method,the effects of the geometric parameters on the response of the microphone have been investigated. Results show that, increasing air gap size, holes radius, and holes number decrease the damping effects of the air between diaphragm and back plate. On the other hand, increasing the distance between the holes has the opposite effect. In addition, results reveal that among these four parameters, increasing the number of holes on back plate is the most efficient method in reducing air-gap damping effects.

Anion-exchange separation of interfering iron from liquid samples for accurate determination of uranium by spectrophotometric method

Muhammad Sajjad,Abdul Aziz,Bashir Mohammad 대한환경공학회 2015 대한환경공학회 학술발표논문집 Vol.2015 No.10

A multifunctional micro-fluidic system for dielectrophoretic concentration coupled with immuno-capture of low numbers of <i>Listeria monocytogenes</i>

Yang, Liju,Banada, Padmapriya P.,Chatni, Mohammad R.,Seop Lim, Kwan,Bhunia, Arun K.,Ladisch, Michael,Bashir, Rashid Royal Society of Chemistry 2006 Lab on a chip Vol.6 No.7

<P>In this study, we demonstrated a micro-fluidic system with multiple functions, including concentration of bacteria using dielectrophoresis (DEP) and selective capture using antibody recognition, resulting in a high capture efficiency of bacterial cells. The device consisted of an array of oxide covered interdigitated electrodes on a flat silicon substrate and a ∼16 µm high and ∼260 µm wide micro-channel within a PDMS cover. For selective capture of <I>Listeria monocytogenes</I> from the samples, the channel surface was functionalized with a biotinylated BSA–streptavidin–biotinylated monoclonal antibody sandwich structure. Positive DEP (at 20 V<SUB>pp</SUB> and 1 MHz) was used to concentrate bacterial cells from the fluid flow. DEP could collect ∼90% of the cells in a continuous flow at a flow rate of 0.2 µl min<SUP>−1</SUP> into the micro-channel with concentration factors between 10<SUP>2</SUP>–10<SUP>3</SUP>, in sample volumes of 5–20 µl. A high flow rate of 0.6 µl min<SUP>−1</SUP> reduced the DEP capture efficiency to ∼65%. Positive DEP attracts cells to the edges of the electrodes where the field gradient is the highest. Cells concentrated by DEP were captured by the antibodies immobilized on the channel surface with efficiencies of 18 to 27% with bacterial cell numbers ranging from 10<SUP>1</SUP> to 10<SUP>3</SUP> cells. It was found that DEP operation in our experiments did not cause any irreversible damage to bacterial cells in terms of cell viability. In addition, increased antigen expression (antigens to C11E9 monoclonal antibody) on cell membranes was observed following the exposure to DEP.</P> <P>Graphic Abstract</P><P>Bacterial cells were concentrated by positive dielectrophoresis. Target cells were selectively captured by specific antibodies immobilized on the channel surface. <IMG SRC='http://pubs.rsc.org/services/images/RSCpubs.ePlatform.Service.FreeContent.ImageService.svc/ImageService/image/GA?id=b607061m'> </P>

Pharmacokinetics and metabolite profiling of fimasartan, a novel antihypertensive agent, in rats

Kim, Tae Hwan,Shin, Soyoung,Bashir, Mohammad,Chi, Yong Ha,Paik, Soo Heui,Lee, Joo Han,Choi, Hyuk Joon,Choi, Jin Ho,Yoo, Sun Dong,Bulitta, Jü,rgen B.,Ma, Eunsook,Joo, Sang Hoon,Shin, Beom Soo Informa UK Ltd. 2014 Xenobiotica Vol.44 No.10

<P>1. <?ri?>The objectives of this study were to evaluate the pharmacokinetics and metabolism of fimasartan in rats.</P><P>2. <?ri?>Unlabeled fimasartan or radiolabeled [<SUP>14</SUP>C]fimasartan was dosed by intravenous injection or oral administration to rats. Concentrations of unlabeled fimasartan in the biological samples were determined by a validated LC/MS/MS assay. Total radioactivity was quantified by liquid scintillation counting and the radioactivity associated with the metabolites was analyzed by using the radiochemical detector. Metabolite identification was conducted by product ion scanning using LC/MS/MS.</P><P>3. <?ri?>After oral administration of [<SUP>14</SUP>C]fimasartan, total radioactivity was found primarily in feces. In bile duct cannulated rats, 58.8 ± 14.4% of the radioactive dose was excreted via bile after oral dosing. Major metabolites of fimasartan including the active metabolite, desulfo-fimasartan, were identified, yet none represented more than 7.2% of the exposure of the parent drug. Fimasartan was rapidly and extensively absorbed and had an oral bioavailability of 32.7-49.6% in rats. Fimasartan plasma concentrations showed a multi-exponential decline after oral administration. Double peaks and extended terminal half-life were observed, which was likely caused by enterohepatic recirculation.</P><P>4. <?ri?>These results provide better understanding on the pharmacokinetics of fimasartan and may aid further development of fimasartan analogs.</P>

Role of Barium Swallow in Diagnosing Clinically Significant Anastomotic Leak following Esophagectomy

Simon Roh,Mark D. Iannettoni,John C. Keech,Mohammad Bashir,Peter J. Gruber,Kalpaj R. Parekh 대한흉부외과학회 2016 Journal of Chest Surgery (J Chest Surg) Vol.49 No.2

Background: Barium swallow is performed following esophagectomy to evaluate the anastomosis for detection of leaks and to assess the emptying of the gastric conduit. The aim of this study was to evaluate the reliability of the barium swallow study in diagnosing anastomotic leaks following esophagectomy. Methods: Patients who underwent esophagectomy from January 2000 to December 2013 at our institution were investigated. Barium swallow was routinely done between days 5–7 to detect a leak. These results were compared to clinically determined leaks (defined by neck wound infection requiring jejunal feeds and or parenteral nutrition) during the postoperative period. The sensitivity and specificity of barium swallow in diagnosing clinically significant anastomotic leaks was determined. Results: A total of 395 esophagectomies were performed (mean age, 62.2 years). The indications for the esophagectomy were as follows: malignancy (n=320), high-grade dysplasia (n=14), perforation (n=27), benign stricture (n=7), achalasia (n=16), and other (n=11). A variety of techniques were used including transhiatal (n=351), McKeown (n=35), and Ivor Lewis (n=9) esophagectomies. Operative mortality was 2.8% (n=11). Three hundred and sixty-eight patients (93%) underwent barium swallow study after esophagectomy. Clinically significant anastomotic leak was identified in 36 patients (9.8%). Barium swallow was able to detect only 13/36 clinically significant leaks. The sensitivity of the swallow in diagnosing a leak was 36% and specificity was 97%. The positive and negative predictive values of barium swallow study in detecting leaks were 59% and 93%, respectively. Conclusion: Barium swallow is an insensitive but specific test for detecting leaks at the cervical anastomotic site after esophagectomy.