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1.
Chemosphere ; 352: 141324, 2024 Mar.
Article in English | MEDLINE | ID: mdl-38296207

ABSTRACT

Non-agricultural sources of pesticides in urban areas are responsible for their presence in domestic wastewater. Therefore, pesticides are typically found in sewage treatment plants in developed and developing countries as micro-pollutant. The presence of pesticides in the wastewater can impart stress on the aerobic sludge biomass and disrupt the functioning of the plant. However, there exists a knowledge gap regarding the resilience of aerobic sludge biomass towards stress due to the presence of pesticides in the wastewater. This study investigated the impact of chlorpyrifos (CPS) - a widely used pesticide, on sludge biomass and explored its recovery capability when CPS is discontinued in the influent. Four duplicate reactors were operated with different CPS concentrations ranging from 50 to 200 mg/L. Chemical oxygen demand (COD) removal for reactors has ranged within 18-73 % at the steady state of the stressed phase, whereas COD removal for the control reactor was 91 %. CPS stress slightly inhibited filamentous biomass growth. Biomass activity and cell viability have decreased significantly, whereas biochemical contents have varied slightly under CPS stress. The activities of the enzymes dehydrogenase and urease were significantly inhibited when compared to catalase and protease. Amplified ribosomal DNA restriction analysis reflected changes in the microbial community. The discontinuation of CPS has allowed aerobic sludge biomass to recover in its organic degradation capability (COD removal of more than 88 % at steady-state conditions of recovery phase operation), biomass growth, and cell viability. In addition, enzyme activities have retrieved to their original levels, and 78-93 % similarity of microbial community structure has been displayed between CPS-exposed and control reactor biomasses. Overall, the present study has indicated the orderly changes in the quality of aerobic sludge biomass under CPS stress through physico-chemical and biological characteristics. The study also has highlighted the self-recovery of sludge biomass characteristics stressed with different concentrations of CPS.


Subject(s)
Chlorpyrifos , Pesticides , Resilience, Psychological , Sewage/chemistry , Wastewater , Waste Disposal, Fluid , Biomass , Bioreactors , Pesticides/analysis , Biological Oxygen Demand Analysis
2.
IEEE ION Position Locat Navig Symp ; 2023: 708-723, 2023 Apr.
Article in English | MEDLINE | ID: mdl-37736264

ABSTRACT

Inertial navigation provides a small footprint, low-power, and low-cost pathway for localization in GPS-denied environments on extremely resource-constrained Internet-of-Things (IoT) platforms. Traditionally, application-specific heuristics and physics-based kinematic models are used to mitigate the curse of drift in inertial odometry. These techniques, albeit lightweight, fail to handle domain shifts and environmental non-linearities. Recently, deep neural-inertial sequence learning has shown superior odometric resolution in capturing non-linear motion dynamics without human knowledge over heuristic-based methods. These AI-based techniques are data-hungry, suffer from excessive resource usage, and cannot guarantee following the underlying system physics. This paper highlights the unique methods, opportunities, and challenges in porting real-time AI-enhanced inertial navigation algorithms onto IoT platforms. First, we discuss how platform-aware neural architecture search coupled with ultra-lightweight model backbones can yield neural-inertial odometry models that are 31-134× smaller yet achieve or exceed the localization resolution of state-of-the-art AI-enhanced techniques. The framework can generate models suitable for locating humans, animals, underwater sensors, aerial vehicles, and precision robots. Next, we showcase how techniques from neurosymbolic AI can yield physics-informed and interpretable neural-inertial navigation models. Afterward, we present opportunities for fine-tuning pre-trained odometry models in a new domain with as little as 1 minute of labeled data, while discussing inexpensive data collection and labeling techniques. Finally, we identify several open research challenges that demand careful consideration moving forward.

3.
BMC Pediatr ; 23(1): 170, 2023 04 13.
Article in English | MEDLINE | ID: mdl-37046243

ABSTRACT

BACKGROUND: Necrotizing pneumonia is rare in children and is one of the most serious complications of a lung infection caused by antibiotic failure. We present a 12-year-old leukopenic child with a long-lasting lung infection, presenting as having a lung hydatid cyst, but diagnosing with necrotizing pneumonia in the right bilobed lung. Failure to medical treatment and ongoing leukopenia justified surgical intervention with positive results. CASE PRESENTATION: The patient was referred to our teaching hospital's pediatric surgery department. He had previously been diagnosed with intestinal tuberculosis (TB) and received anti-TB treatment. On referral to our hospital, the patient was suffering from restlessness, frequent coughing, fever, vomiting, and diarrhea. Following the completion of the clinical work-up, a blood test revealed leukopenia (white blood cell count of 2100/microliter), a normal platelet count, and a lesion in the right lung. Computerized tomography scanning (CT-Scan) image reported a lung hydatid cyst. In the pediatrics ward, a broad-spectrum antibiotics regimen with triple-antibiotic therapy (linezolid, vancomycin, and metronidazole) was instituted and continued for a week with no response, but worsening of the condition. In the pediatric surgery ward, our decision for surgical intervention was due to the failure of medical treatment because of a pulmonary lesion. Our team performed right lung upper lobe anterior segment wedge resection due to necrotizing pneumonia and followed the patient 45 days post-operation with a reasonable result. CONCLUSION: Living in remote rural areas with low resources and inaccessibility to proper and specialized diagnostic and treatment centers will all contribute to an improper diagnosis and treatment of lung infection. In total, all of these will increase the morbidity and mortality due to lung necrosis in the pediatric population, regardless of their age. In low-resource facilities, high-risk patients can benefit from surgical intervention to control the ongoing infection process.


Subject(s)
Echinococcosis , Leukopenia , Pneumonia, Necrotizing , Pneumonia , Male , Child , Humans , Pneumonia, Necrotizing/diagnosis , Pneumonia, Necrotizing/surgery , Pneumonia, Necrotizing/drug therapy , Lung/diagnostic imaging , Lung/surgery , Lung/pathology , Pneumonia/diagnosis , Pneumonia/etiology , Pneumonia/drug therapy , Anti-Bacterial Agents/therapeutic use , Echinococcosis/drug therapy , Echinococcosis/pathology
4.
Int J Surg Case Rep ; 106: 108216, 2023 May.
Article in English | MEDLINE | ID: mdl-37068457

ABSTRACT

INTRODUCTION AND IMPORTANCE: Mesenteric cysts are uncommon intra-abdominal benign masses that appear in childhood with varying degrees of clinical manifestations, ranging from being asymptomatic to presenting as an acute abdomen. The diagnosis is made incidentally during the work-up for other abdominal pathologies such as acute appendicitis, bowel obstruction, etc. The treatment is mostly surgical and varies depending on the clinical type of the lesion. CASE PRESENTATION: A 26-month-old child was referred to our teaching hospital's pediatric surgery department with an abdominal mass. The patient had previously complained of constipation and been treated symptomatically with laxatives. Ultrasonography reported ovarian cysts confirmed by computerized tomography scanning (as a misdiagnosis report of an ovarian cyst instead of a mesenteric cyst), done outside the hospital in a private diagnostic center. CLINICAL DISCUSSION: The patient was prepared for operation and during the surgical procedure, she was found to have a duplex cyst, which was mostly incorporated in the mesentery of the distal 1/3 of the transverse mesocolon. The cyst was enucleated through a lower midline laparotomy incision without bowel resection and anastomosis. The histopathological analysis of the specimen confirmed a mesenteric cyst. CONCLUSION: Mesenteric cysts are rare lesions in children and should be considered when approaching any intra-abdominal mass. Except for the rare cases where intestinal resection and/or partial cyst excision are required, all mesenteric cysts can be excised while preserving intestinal integrity and vascular supply.

5.
Sci Robot ; 8(77): eadf4753, 2023 Apr 19.
Article in English | MEDLINE | ID: mdl-37075101

ABSTRACT

As the field of soft robotics advances, full autonomy becomes highly sought after, especially if robot motion can be powered by environmental energy. This would present a self-sustained approach in terms of both energy supply and motion control. Now, autonomous movement can be realized by leveraging out-of-equilibrium oscillatory motion of stimuli-responsive polymers under a constant light source. It would be more advantageous if environmental energy could be scavenged to power robots. However, generating oscillation becomes challenging under the limited power density of available environmental energy sources. Here, we developed fully autonomous soft robots with self-sustainability based on self-excited oscillation. Aided by modeling, we have successfully reduced the required input power density to around one-Sun level through a liquid crystal elastomer (LCE)-based bilayer structure. The autonomous motion of the low-intensity LCE/elastomer bilayer oscillator "LiLBot" under low energy supply was achieved by high photothermal conversion, low modulus, and high material responsiveness simultaneously. The LiLBot features tunable peak-to-peak amplitudes from 4 to 72 degrees and frequencies from 0.3 to 11 hertz. The oscillation approach offers a strategy for designing autonomous, untethered, and sustainable small-scale soft robots, such as a sailboat, walker, roller, and synchronized flapping wings.

6.
Int J Pharm ; 627: 122189, 2022 Nov 05.
Article in English | MEDLINE | ID: mdl-36100147

ABSTRACT

We explored the potential of cellulose nanofiber (CNF) for designing prolonged-release, thin-film drug delivery systems (TF-DDS). These delivery systems can be used as locally deployable drug-releasing scaffolds for achieving spatial and temporal control over therapeutic concentration in target tissues. Using doxorubicin (DOX) as a model anticancer drug, CNF-based TF-DDS were prepared using different film-formation processes, such as solvent casting and lyophilization. Formulations were prepared with or without the incorporation of additional macromolecular additives, such as gelatin, to include further biomechanical functionality. We studied the films for their mechanical properties, thermal stability, wettability, porosity and in vitro drug release properties. Our experimental results showed that CNF-based films, when prepared via solvent casting method, showed optimized performance in terms of DOX loading, and prolonged-release than those prepared via lyophilization-based fabrication processes. Scanning electron microscopy (SEM) analysis of the CNF-based films showed uniform distribution of fiber entanglement, which provided the scaffolds with sufficient porosity and tortuosity contributing to the sustained release of the drug from the delivery system. We also observed that surface layering of gelatin on CNF films via dip-coating significantly increased the mechanical strength and reduced the wettability of the films, and as such, affected drug release kinetics. The performance of the TF-DDS was evaluated in-vitro against two pancreatic cancer cell lines, i.e. MIA PaCa-2 and PANC-1. We observed that, along with the enhancement of mean dissolution time (MDT) of DOX, CNF-based TF-DDS were able to suppress the proliferation of pancreatic cancer cells in a time-dependent fashion, indicating that the drug liberated from the films were therapeutically active against cancer cells. Additionally, TF-DDS were also tested ex-vivo on patient-derived xenograft (PDX) model of pancreatic ductal adenocarcinoma (PDAC). We observed that DOX released from the TF-DDS was able to reduce Ki-67 positive, pancreatic cancer cells in these models.


Subject(s)
Nanofibers , Pancreatic Neoplasms , Humans , Cellulose , Delayed-Action Preparations , Doxorubicin/pharmacology , Drug Delivery Systems , Gelatin , Ki-67 Antigen , Pancreatic Neoplasms/drug therapy , Solvents , Animals
7.
Biophys J ; 121(18): 3358-3369, 2022 09 20.
Article in English | MEDLINE | ID: mdl-36028999

ABSTRACT

The mechanical properties of tissues have profound impacts on a wide range of biological processes such as embryo development (1,2), wound healing (3-6), and disease progression (7). Specifically, the spatially varying moduli of cells largely influence the local tissue deformation and intercellular interaction. Despite the importance of characterizing such a heterogeneous mechanical property, it has remained difficult to measure the supracellular modulus field in live cell layers with a high-throughput and minimal perturbation. In this work, we developed a monolayer effective modulus measurement by integrating a custom cell stretcher, light microscopy, and AI-based inference. Our approach first quantifies the heterogeneous deformation of a slightly stretched cell layer and converts the measured strain fields into an effective modulus field using an AI inference. This method allowed us to directly visualize the effective modulus distribution of thousands of cells virtually instantly. We characterized the mean value, SD, and correlation length of the effective cell modulus for epithelial cells and fibroblasts, which are in agreement with previous results. We also observed a mild correlation between cell area and stiffness in jammed epithelia, suggesting the influence of cell modulus on packing. Overall, our reported experimental platform provides a valuable alternative cell mechanics measurement tool that can be integrated with microscopy-based characterizations.


Subject(s)
Epithelial Cells , Elastic Modulus , Stress, Mechanical
8.
Phys Rev E ; 105(3-1): 034401, 2022 Mar.
Article in English | MEDLINE | ID: mdl-35428095

ABSTRACT

In this paper, three-dimensional numerical simulations of ballooning in spiders using multiple silk threads are performed using the discrete elastic rods method. The ballooning of spiders is hypothesized to be caused by the presence of the negative electric charge of the spider silk threads and the positive electric potential field in the Earth's atmosphere. The numerical model presented here is first validated against experimental data from the open literature. After which, two cases are examined, in the first it is assumed that the electric charge is uniformly distributed along the threads while in the second, the electric charge is located at the thread tip. It is shown that the normalized terminal ballooning velocity, i.e., the velocity at which the spiders balloon after they reach steady-state, decrease linearly with the normalized lift force, especially for the tip located charge case. For the uniform electric charge case, this velocity shows a slightly weaker dependence on the normalized lift force. Moreover, it is shown in both cases that the normalized terminal ballooning velocity has no dependence on the normalized elastic bending stiffness of the threads and on the normalized viscous forces. Finally, the multithread bending process shows a three-dimensional conical sheet. Here we show that this behavior is caused by the Coulomb repelling forces owing to the threads electric charge which leads to dispersing the threads apart and thus avoid entanglement.

9.
Environ Sci Pollut Res Int ; 29(41): 61954-61966, 2022 Sep.
Article in English | MEDLINE | ID: mdl-35378654

ABSTRACT

Heavy metals in higher concentrations are often encountered in domestic sewage of developing and under-developed countries. High metallic concentrations can stress reactor sludge biomass morphology impeding its performance in organics reduction. However, the extent of damage and ability of sludge biomass to recover from the metallic stress is not fully understood. Also, there is no protocol to identify and prevent the sludge biomass from metallic stress in fully functional sewage treatment plants (STPs). This study investigates performance, metabolic activity, morphology, and settling characteristics of the sludge biomass under different Co(II) stress conditions. The extent of recovery in biomass, when the supply of Co(II) metal ion was discontinued in the inlet stream, was explored. The study also proposed a protocol based on simple settling characteristics of sludge biomass to get an early indication of metal infiltration to prevent potential damage to the biomass morphology. Four sequencing batch reactors (SBRs) with Co(II) ion concentrations of 0 (designated as RCo0), 5 (RCo5), 25 (RCo25), and 75 mg/L (RCo75) in the feed were operated with a cycle time of 12 h. Reactors were operated for 35 days with Co(II) in the feed (termed as stressed phase operation) followed by 24 days of operation without Co(II) in the feed (termed as recovery phase operation). Results show that COD removal in reactor RCo75 reduced to 48% on the 10th day of stressed phase operation, showing a lag in COD removal due to metallic stress. The activity of biomass in reactors RCo5, RCo25, and RCo75 was reduced by 39%, 45%, and 49%, respectively, in the stressed phase compared to the biomass in control reactor. Recovery in COD removal efficiency and specific biomass activity were observed in all the reactors after the removal of metallic stress. The settleability of sludge biomass in reactors RCo25 and RCo75 was significantly affected. Transformation in the shape of flocs in reactor RCo25 and RCo75 biomasses revealed the prolonged effect of metallic stress, which was observed to be irreversible even during the recovery phase operation.


Subject(s)
Sewage , Waste Disposal, Fluid , Biomass , Bioreactors , Waste Disposal, Fluid/methods
10.
Radiol Case Rep ; 16(2): 343-347, 2021 Feb.
Article in English | MEDLINE | ID: mdl-33312321

ABSTRACT

Urothelial carcinoma and nephrolithiasis are a common cause of obstructive uropathy which can be relieved by percutaneous nephrostomy catheter placement. A rare, but known complication of this procedure is iatrogenic seeding of tumor cells along the nephrostomy tract. We describe a case of 68-year-old-female with cutaneous metastasis of high-grade urothelial carcinoma with seeding of tumor cells along the percutaneous nephrostomy catheter tract 8 months after the removal of the catheter. Given its severity, interventional radiologists should be mindful of the number of percutaneous access attempts, exchanges, and catheter manipulations in patients with urothelial carcinoma due to the risk of metastatic seeding along the percutaneous tract or to nearby tissues.

11.
Water Res ; 165: 114989, 2019 Nov 15.
Article in English | MEDLINE | ID: mdl-31434014

ABSTRACT

Piped water supply in Guwahati covers less than 30% of the city's population for which the Government of India proposes four new water supply projects, but astonishingly, they faced vehement public protest. The reason for the protest was attributed to lack of trust and need of public representation in the governing body. Besides, public participation is not a mandatory clause in water supply projects and, hence, was not carried out a priori to the project implementation. In an effort to address this, the present study aims to develop a framework incorporating public participation as a mandatory clause in water supply projects. In doing so, secondary data was collected from studies worldwide on public participation in water supply projects and analyzed to identify critical success factors (CSFs). South-West Guwahati water supply project was taken up as a study area, and a semi-structured questionnaire was designed to generate primary data on public participation. Thematic analysis was employed to identify the CSFs from primary data influencing public participation in the project. Finally, a framework was formulated following the identified CSFs from primary and secondary data and the review of various theories on public participation. The framework is developed to achieve effective public participation in six levels viz. inform, educate, consult, involve, collaborate, and capacity building. Each level satisfies a set of CSFs and ultimately all CSFs addresses to deemphasize the effects of disincentives in water supply projects. Further, the framework was validated by 16 experts and received an exceptionally copacetic rating for all six validation aspects. Copacetic expert ratings demonstrated appropriateness, objectivity, replicability, practicality, reliability, and suitability of framework for water supply projects.


Subject(s)
Community Participation , Water Supply , Humans , India , Reproducibility of Results
12.
Sci Robot ; 3(25)2018 12 19.
Article in English | MEDLINE | ID: mdl-33141693

ABSTRACT

By using compliant lightweight actuators with shape memory alloy, we created untethered soft robots that are capable of dynamic locomotion at biologically relevant speeds.

13.
Proc Natl Acad Sci U S A ; 115(1): 75-80, 2018 01 02.
Article in English | MEDLINE | ID: mdl-29255048

ABSTRACT

Elastic gridshells comprise an initially planar network of elastic rods that are actuated into a shell-like structure by loading their extremities. The resulting actuated form derives from the elastic buckling of the rods subjected to inextensibility. We study elastic gridshells with a focus on the rational design of the final shapes. Our precision desktop experiments exhibit complex geometries, even from seemingly simple initial configurations and actuation processes. The numerical simulations capture this nonintuitive behavior with excellent quantitative agreement, allowing for an exploration of parameter space that reveals multistable states. We then turn to the theory of smooth Chebyshev nets to address the inverse design of hemispherical elastic gridshells. The results suggest that rod inextensibility, not elastic response, dictates the zeroth-order shape of an actuated elastic gridshell. As it turns out, this is the shape of a common household strainer. Therefore, the geometry of Chebyshev nets can be further used to understand elastic gridshells. In particular, we introduce a way to quantify the intrinsic shape of the empty, but enclosed regions, which we then use to rationalize the nonlocal deformation of elastic gridshells to point loading. This justifies the observed difficulty in form finding. Nevertheless, we close with an exploration of concatenating multiple elastic gridshell building blocks.

14.
Soft Matter ; 12(6): 1898-905, 2016 Feb 14.
Article in English | MEDLINE | ID: mdl-26738932

ABSTRACT

We perform a numerical investigation of the deformation of a rotating helical filament subjected to an axial flow, under low Reynolds number conditions, motivated by the propulsion of bacteria using helical flagella. Given its slenderness, the helical rod is intrinsically soft and deforms due to the interplay between elastic forces and hydrodynamic loading. We make use of a previously developed and experimentally validated computational tool framework that models the elasticity of the filament using the discrete elastic rod method and the fluid forces are treated using Lighthill's slender body theory. Under axial flow, and in the absence of rotation, the initially helical rod is extended. Above a critical flow speed its configuration comprises a straight portion connected to a localized helix near the free end. When the rod is also rotated about its helical axis, propulsion is only possible in a finite range of angular velocity, with an upper bound that is limited by buckling of the soft helix arising due to viscous stresses. A systematic exploration of the parameter space allows us to quantify regimes for successful propulsion for a number of specific bacteria.


Subject(s)
Elasticity , Flagella/chemistry , Bacterial Physiological Phenomena , Biomechanical Phenomena , Flagella/physiology , Models, Theoretical , Movement , Rotation
15.
Proc Natl Acad Sci U S A ; 111(41): 14663-8, 2014 Oct 14.
Article in English | MEDLINE | ID: mdl-25267649

ABSTRACT

We investigate the deployment of a thin elastic rod onto a rigid substrate and study the resulting coiling patterns. In our approach, we combine precision model experiments, scaling analyses, and computer simulations toward developing predictive understanding of the coiling process. Both cases of deposition onto static and moving substrates are considered. We construct phase diagrams for the possible coiling patterns and characterize them as a function of the geometric and material properties of the rod, as well as the height and relative speeds of deployment. The modes selected and their characteristic length scales are found to arise from a complex interplay between gravitational, bending, and twisting energies of the rod, coupled to the geometric nonlinearities intrinsic to the large deformations. We give particular emphasis to the first sinusoidal mode of instability, which we find to be consistent with a Hopf bifurcation, and analyze the meandering wavelength and amplitude. Throughout, we systematically vary natural curvature of the rod as a control parameter, which has a qualitative and quantitative effect on the pattern formation, above a critical value that we determine. The universality conferred by the prominent role of geometry in the deformation modes of the rod suggests using the gained understanding as design guidelines, in the original applications that motivated the study.

16.
Prep Biochem Biotechnol ; 43(7): 717-34, 2013.
Article in English | MEDLINE | ID: mdl-23768115

ABSTRACT

The present study describes the usage of dried leafy biomass of mango (Mangifera indica) containing 26.3% (w/w) cellulose, 54.4% (w/w) hemicellulose, and 16.9% (w/w) lignin, as a substrate for bioethanol production from Zymomonas mobilis and Candida shehatae. The substrate was subjected to two different pretreatment strategies, namely, wet oxidation and an organosolv process. An ethanol concentration (1.21 g/L) was obtained with Z. mobilis in a shake-flask simultaneous saccharification and fermentation (SSF) trial using 1% (w/v) wet oxidation pretreated mango leaves along with mixed enzymatic consortium of Bacillus subtilis cellulase and recombinant hemicellulase (GH43), whereas C. shehatae gave a slightly higher (8%) ethanol titer of 1.31 g/L. Employing 1% (w/v) organosolv pretreated mango leaves and using Z. mobilis and C. shehatae separately in the SSF, the ethanol titers of 1.33 g/L and 1.52 g/L, respectively, were obtained. The SSF experiments performed with 5% (w/v) organosolv-pretreated substrate along with C. shehatae as fermentative organism gave a significantly enhanced ethanol titer value of 8.11 g/L using the shake flask and 12.33 g/L at the bioreactor level. From the bioreactor, 94.4% (v/v) ethanol was recovered by rotary evaporator with 21% purification efficiency.


Subject(s)
Cellulase/chemistry , Ethanol/chemical synthesis , Mangifera/chemistry , Plant Leaves/chemistry , Bacillus subtilis/enzymology , Biomass , Bioreactors , Ethanol/chemistry , Fermentation , Hydrolysis , Lignin/chemistry , Polysaccharides/chemistry , Recombinant Proteins/chemistry , Recombinant Proteins/pharmacology , Zymomonas
17.
J Water Health ; 11(2): 224-43, 2013 Jun.
Article in English | MEDLINE | ID: mdl-23708571

ABSTRACT

Groundwater in Assam, India, contains excessive amounts of arsenic (As(III)), fluoride (F(-)) and iron (Fe(II)). The rural and semi-urban population of Assam uses indigenous iron filters fabricated using processed sand (PS) as one of the chief constituents to reduce Fe(II) concentration; however, no efforts have been made to reduce As(III) or F(-) concentrations before use. The present work is directed towards assessing the potential of PS for removal of these ions from mono-, binary- and ternary-ion systems through continuous mode column studies. Synthetic water samples containing fixed concentration of ions were prepared using deionized water. The observed order of breakthrough of ions was: As(III) followed by Fe(II) and F(-) followed by Fe(II) in the case of the binary ion systems of Fe(II) + As(III) and Fe(II) + F(-). The throughput volume for As(III) in the (Fe(II) + As(III)) system and for F(-) in the (Fe(II) + F(-)) system is termed the critical breakthrough throughput volume. In the ternary ion system (Fe(II) + As(III) + F(-)), the order of breakthrough of ions observed was F(-), then As(III) and then Fe(II) and hence the throughput volume F(-) is termed the critical breakthrough throughput volume. Results of column studies also indicate the impact on the uptake of the selected ion by the presence of the other ion present in the binary- and ternary-ion systems.


Subject(s)
Arsenic/chemistry , Fluorine/chemistry , Groundwater/chemistry , Iron/chemistry , Silicon Dioxide/chemistry , Water Purification/methods , India , Rivers , Water Pollutants, Chemical/chemistry
18.
Prep Biochem Biotechnol ; 43(3): 256-70, 2013.
Article in English | MEDLINE | ID: mdl-23379273

ABSTRACT

An extracellular alkaline carboxymethycellulase (CMCase) from Bacillus subtilis was purified by salt precipitation followed by anion-exchange chromatography using DEAE-Sepharose. The cell-free supernatant containing crude enzyme had a CMCase activity of 0.34 U/mg. The purified enzyme gave a specific activity of 3.33 U/mg, with 10-fold purification and an overall activity yield of 5.6%. The purified enzyme displayed a protein band on sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) with an apparent molecular size of 30 kDa, which was also confirmed by zymogram analysis. The enzyme displayed multisubstrate specificity, showing significantly higher activity with lichenan and ß-glucan as compared to carboxymethylcellulose (CMC), laminarin, hydroxyethylcellulose, and steam-exploded bagasse, and negligible activity with crystalline substrate such as Avicel and filter paper. It was optimally active at pH 9.2 and temperature 45°C. The enzyme was stable in the pH range 6-10 and retained 70% activity at pH 12. Thermal stability analysis revealed that the enzyme was stable in temperature range of 20°C to 45°C and retained more than 50% activity at 60°C for 30 min. The enzyme had a Km of 0.13 mg/ml and Vmax of 3.38 U/mg using CMC as substrate.


Subject(s)
Bacillus subtilis/enzymology , Carboxymethylcellulose Sodium/isolation & purification , Carboxymethylcellulose Sodium/metabolism , Cellulose/analogs & derivatives , Cellulose/metabolism , Chromatography, Ion Exchange/methods , Electrophoresis, Polyacrylamide Gel , Enzyme Stability , Glucans , Hydrogen-Ion Concentration , Kinetics , Molecular Weight , Polysaccharides/metabolism , Substrate Specificity , Temperature , beta-Glucans/metabolism
19.
ISRN Biotechnol ; 2013: 965310, 2013.
Article in English | MEDLINE | ID: mdl-25937985

ABSTRACT

Effect of physical parameters such as initial pH, agitation (rpm), and temperature (°C) for cellulase production from Bacillus subtilis AS3 was investigated. Central composite design of experiments followed by multiple desirability function was applied for the optimization of cellulase activity and cell growth. The effect of the temperature and agitation was found to be significant among the three independent variables. The optimum levels of initial pH, temperature, and agitation for alkaline carboxymethylcellulase (CMCase) production predicted by the model were 7.2, 39°C, and 121 rpm, respectively. The CMCase activity with unoptimized physical parameters and previously optimized medium composition was 0.43 U/mL. The maximum activity (0.56 U/mL) and cell growth (2.01 mg/mL) predicted by the model were in consensus with values (0.57 U/mL, 2.1 mg/mL) obtained using optimized medium and optimal values of physical parameters. After optimization, 33% enhancement in CMCase activity (0.57 U/mL) was recorded. On scale-up of cellulase production process in bioreactor with all the optimized conditions, an activity of 0.75 U/mL was achieved. Consequently, the bacterial cellulase employed for bioethanol production expending (5%, w/v) NaOH-pretreated wild grass with Zymomonas mobilis yielded an utmost ethanol titre of 7.56 g/L and 11.65 g/L at shake flask and bioreactor level, respectively.

20.
J Environ Sci Eng ; 49(4): 241-6, 2007 Oct.
Article in English | MEDLINE | ID: mdl-18476369

ABSTRACT

Ground water, the major source of drinking water in rural and semi-urban areas of Assam, contains an excessive amount of iron varying from 1 to 10 mg/L or more. People in Assam invariably use household iron filter units-indigenously developed using locally available wooden charcoal and river sand as filter media. The present work is aimed to evaluate effectiveness of wooden charcoal and river sand for its iron adsorption capacity. The experiments were carried at a fixed pH of 5.5 with zero dissolved oxygen levels. Batch kinetic studies indicated rapid uptake of Fe(II) by wooden charcoal in the first 20 min. while the uptake with sand was relatively slower. The adsorption seemed to govern by diffusion within pores of adsorbents and Fe(II) removal mechanism appeared to be complex. Equilibrium studies indicated favorable adsorption of Fe(II) on both adsorbents and followed Langmuir isotherm. Column studies indicated relatively quicker breakthrough through sand bed as compared to charcoal bed. Overall, wooden charcoal and sand both seemed to have potentials for Fe(II) removal.


Subject(s)
Iron/analysis , Water Purification/instrumentation , Water Purification/methods , Water Supply , Adsorption , Charcoal , Equipment Design , Family Characteristics , Filtration , Humans , Hydrogen-Ion Concentration , India , Iron/chemistry , Rural Population , Silicon Dioxide , Waste Disposal, Fluid/methods , Water Pollutants, Chemical/analysis
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