Enzyme-Based Biosensors for Electrochemical Detection of Pesticides–A Mini Review

Despite their important contribution in increasing crops production, most pesticides are harmful to humans and living beings and can persist in the environment over long a long duration. Traditional chromatographic methods of analysis are expensive and cumbersome. Biosensor technology appears therefore as an efficient and economical alternative for fast detection of pesticides. The devices are portable, rapid, and highly sensitive. Other important features of the devices are their relatively high sensistivity and low response time. Enzymatic biosensors for pesticide detection rely either on the inhibition mechanism or on the catalytic activity of the immobilized enzyme toward a specific pesticide. Metal and carbon based nanomaterials are being widely used as immobilization support owing to novel characteristics such as biocompatibility and enhanced electron transfer ability for sensitive electrochemical detection, among others. This review focusses on the electrochemical detection of organophosphorus pesticides, delineating the limit of detection and response time of biosensors toward a wide range of organophosphorus pesticides

The optimum condition for the synthesis of carbon nanofibers on activated carbon to remove lead from aqueous solution

Optimum process condition for the production of Carbon Nanofibers (CNFs) to remove lead ion (Pb) from aqueous solution is reported here. The CNFs were produced on the catalyst (Ni2+) impregnated palm oil-based cheap Powder Activated Carbon (PAC). Locally fabricated Chemical Vapour Deposition (CVD) system was used while acetylene (C2H2) was the carbon source. The porous nano-composite product is named “PAC-CNFs”, which was synthesized through a process using impregnated oil palm shell based PAC as a solid substrate. Design Expert 6.0.8 software was used to design the experimental plan and to determine the optimized process parameters for the growth of CNFs by using sorption capacity for Pb2+ by the PAC-CNFs adsorbent, as a response. The effect of different factors on the growth of CNFs including the temperature of CNFs growth (550 to 750 °C), time of growth (30 to 60 min), and the ratio of input C2H2/H2 gases (0.25 to 1.0) was evaluated. The predicted values for the sorption capacity of Pb2+ by the PAC-CNFs were in close agreement with the experimental data (R2 = 0.99). The optimal process condition: temperature for the growth of CNFs, time, and C2H2/H2 ratio was determined as 637 °C, 30 min, and 1.0, respectively. The CNFs grown under the optimized condition exhibited sorption capacity of 77 mg/g in removing Pb2+ from synthetic wastewater containing lead (Pb2+) ion

Maleated high oleic sunflower oil-treated cellulose fiber-based styrene butadiene rubber composites

Surface treatment of cellulose fibers was performed with maleated high oleic sunflower oil (MSOHO). The MSOHO-treated cellulose fibers and unmodified cellulose fibers were dispersed in styrene butadiene rubber (SBR) using a two roll mill. Vapor grown carbon nanofibers (VGCNF) were also incorporated at only one parts per hundred rubber (phr) in unmodified cellulose fibers/SBR composites. The curing characteristics, mechanical properties, and water absorption of the resulting composites were determined. MSOHO-treated fibers completed curing at much slower rate and also decreased the cure density of composites, compared to unmodified fibers. In contrast, the combination of VGCNF and unmodified cellulose fibers accelerated the SBR curing process, but reduced the cure density. MSOHO treatment improved the dispersion of the fibers in the SBR, which resulted in improved mechanical properties of composites. The composite incorporating 1 phr VGCNF and 15 phr unmodified cellulose fibers showed the greatest increase in tensile strength as compared with neat SBR

Chemical Characterization and Detection of Adulteration in Essential Oil of Lavandula Angustifolia Linn. by ATR-FTIR

Lavandula angustifolia Linn. (Lavender) is an important source of high-quality fragrance and possesses several pharmacological activities such as antianxiety, antidepressant and hypnotic. Because of its high market price and medicinal values, adulteration is very common with L. angustifolia essential oil. The aim of present study is to characterize essential oil and detect adulteration in it by ATR-FTIR method. L. angustifolia essential oil was isolated by the hydrodistillation method and characterized by GC/MS and FTIR. The authentic isolated essential oil of L. angustifolia was further adulterated by sesame oil (0, 5, 10, 20, 30, 40, 50 and 100% v/v) and analyzed by FTIR. The GC/MS analysis of essential oil of L. angustifolia yielded 74 compounds and linalyl acetate (39.28%), linalool (26.76%), and trans--caryophyllene (4.77%) were found as major chemical compounds. The ATR-FTIR results of isolated pure essential oil of L. angustifolia showed characteristic peaks of linalool and linalyl acetate, the major chemical components present in it. For detection of adulteration in L. angustifolia essential oil, different binary-mixtures of L. angustifolia essential oil with sesame oil (0, 5, 10, 20, 30, 40, 50 and 100% v/v) were analyzed, and the results of FTIR analysis shows very strong peaks in the range of 2800 to 3000 cm-1 and at 1739.31 cm-1 in case of adulterated mixtures compared to the pure essential oil of L. angustifolia. The proposed method was found a simple, economic, quick, reliable, and reproducible for the detection of adulteration in L. angustifolia essential oil

Patients' satisfaction and opinions of their experiences during admission in a tertiary care hospital in Pakistan – a cross sectional study

<p>Abstract</p> <p>Background</p> <p>It is often felt that developing countries need to improve their quality of healthcare provision. This study hopes to generate data that can help managers and doctors to improve the standard of care they provide in line with the wishes of the patients.</p> <p>Methods</p> <p>It was a cross sectional study carried out at a major tertiary care hospital of Karachi. Patients between the ages of 18 and 80 years admitted to the hospital for at least one day were included. Patients in the maternity, psychiatry and chemotherapy wards and those in the ICU/CCU were excluded. A pretested, peer reviewed translation of a validated patient satisfaction scale developed by the Picker Institute of Europe was administered.</p> <p>Results</p> <p>A total of 173 patients (response rate: 78.6 %) filled the questionnaire. Patient satisfaction was at levels comparable to European surveys for most aspects of hospital care. However, nearly half the patients (48%) felt they had to wait too long to get a bed in the hospital after presenting to the ER. 68.6% of the patients said that they were never asked for views on the quality of care provided. 20% of the patients did not find anyone in the staff to talk to about their worries and fears while 27.6% felt that they were given emotional support to only some extent. Up to one third of the patients said they were not provided enough information regarding their operative procedures beforehand.</p> <p>Conclusion</p> <p>Although several components of patient care equal the quality levels of the west, many sections require considerable improvement in order to improve health care provision. The healthcare team needs to get more involved with the patients, providing them greater support and keeping them informed and involved with their medical treatment. Efforts should be made to get regular feedback from the patients.</p

Phenylalanine-Rich Peptides Potently Bind ESAT6, a Virulence Determinant of Mycobacterium tuberculosis, and Concurrently Affect the Pathogen's Growth

BACKGROUND:The secretory proteins of Mycobacterium tuberculosis (M. tuberculosis) have been known to be involved in the virulence, pathogenesis as well as proliferation of the pathogen. Among this set, many proteins have been hypothesized to play a critical role at the genesis of the onset of infection, the primary site of which is invariably the human lung. METHODOLOGY/PRINCIPAL FINDINGS:During our efforts to isolate potential binding partners of key secretory proteins of M. tuberculosis from a human lung protein library, we isolated peptides that strongly bound the virulence determinant protein Esat6. All peptides were less than fifty amino acids in length and the binding was confirmed by in vivo as well as in vitro studies. Curiously, we found all three binders to be unusually rich in phenylalanine, with one of the three peptides a short fragment of the human cytochrome c oxidase-3 (Cox-3). The most accessible of the three binders, named Hcl1, was shown also to bind to the Mycobacterium smegmatis (M. smegmatis) Esat6 homologue. Expression of hcl1 in M. tuberculosis H37Rv led to considerable reduction in growth. Microarray analysis showed that Hcl1 affects a host of key cellular pathways in M. tuberculosis. In a macrophage infection model, the sets expressing hcl1 were shown to clear off M. tuberculosis in much greater numbers than those infected macrophages wherein the M. tuberculosis was not expressing the peptide. Transmission electron microscopy studies of hcl1 expressing M. tuberculosis showed prominent expulsion of cellular material into the matrix, hinting at cell wall damage. CONCLUSIONS/SIGNIFICANCE:While the debilitating effects of Hcl1 on M. tuberculosis are unrelated and not because of the peptide's binding to Esat6-as the latter is not an essential protein of M. tuberculosis-nonetheless, further studies with this peptide, as well as a closer inspection of the microarray data may shed important light on the suitability of such small phenylalanine-rich peptides as potential drug-like molecules against this pathogen

Nonlinear stability, rupture and morphological phase separation of thin fluid films on the apolar and polar substrates

The total free energy (per unit area) of a thin film on a substrate depends on the film thickness, and the apolar (Lifshitz-van der Waals) and polar (acid-base) spreading coefficients for the system. The free interface of the film becomes unstable and deforms when the second derivative of the free energy (i.e., force per unit volume) is negative. The film stability, kinetics of surface deformation, and the resulting morphology are investigated based on numerical solutions of a nonlinear, dynamic equation for the film thickness. A true rupture of the film always occurs when both the apolar (S<SUP>LW</SUP>) and polar (S<SUP>P</SUP>) components of the spreading pressure, S are negative; i.e., the equilibrium contact angle of the corresponding macroscopic drop is finite. However, the true time of rupture evaluated from the nonlinear formalism may be several orders of magnitude larger or smaller than the results of the linear stability analysis, depending on the mean film thickness, relative magnitudes of the apolar and polar forces, and amplitude and wavelength of initial perturbations. When one of the components of the total force is repulsive (either S<SUP>LW</SUP> or S<SUP>P</SUP> is positive), the film breakup occurs only if some localized, narrow regions of the film develop sufficient pent-up kinetic energy to penetrate the (positive) force barrier. Failing this, the thin film undergoes a "morphological phase separation," where nanodrops of the fluid attain equilibrium with relatively flat thin films. Some of the interesting observations that emerge are: (a) Films thicker than a certain critical thickness show true breakup, whereas thinner films may merely undergo a morphological phase separation, but a true dewetting of the substrate does not occur; (b) a thin film may be unstable to the extent of rupturing, even when a macroscopic drop of the same system is predicted to be completely wetting from the Young equation; and (c) a thin film may be stable despite a finite contact angle for the corresponding macrodrop. The underlying physics of observations is constructed by selective use of numerical simulations. Comparisons with predictions of the linear theory reveal that the latter fails, both qualitatively and quantitatively, in accounting for the stability and dynamics of thin films

Morphological phase separation in thin liquid films: II. Equilibrium contact angles of nanodrops coexisting with thin films

When the apolar (LW) and polar (P) components of the spreading pressure (S<SUP>LW</SUP>, S<SUP>P</SUP>) are of opposite signs, thin non-equilibrium films can undergo a morphological phase separation (MPS) manifested as a periodic structure of nanodrops in stable coexistence with thinner flat films. The morphology, film pressure, and equilibrium contact angles of the resulting stable microscopic drops are investigated based on the nonlinear dynamics of the growth and saturation of the film-instability. The equilibrium contact angles of microscopic drops are substantially smaller than those of their macroscopic counterparts, which are only attained for relatively large drops. Simulations show that the equilibrium film pressure of the microdrop is largely independent of the drop size, and may be assumed to be the same as for the corresponding large drop in calculations of the contact angle. The reasons microdrop angles are smaller are: that (a) a significant portion of the drop (and not just the contact zone) experiences excess intermolecular interactions, and (b) due to the large curvature of the drop, the capillary pressure is not always negligible compared to the disjoining/conjoining pressure. The contact angles of type II systems (S<SUP>LW</SUP> &lt; 0, S<SUP>P</SUP> &gt; 0) are very small compared to those of type IV systems (S<SUP>LW</SUP> &gt; 0, SP &lt; 0) for the same value of the total spreading coefficient, S, because of significant film pressure, II → S, for type II systems. Finally, thick films of type IV systems remain stable (wetting), but thin films evolve into microdrops of finite contact angles, regardless of the sign of the spreading pressure

Stability of thin polar films on non-wettable substrates

The linear and non-linear stabilities of thin (&#60;50 nm) apolar and polar films (water, polymers) on non-wettable substrates are correlated to the macroscopic parameters of wetting. The wavelength of instability and the time of film rupture decline as the substrate becomes less wettable by macroscopic drops. The instability of relatively thick (&#62;12 nm) completely polar films (e.g. water films bounded by octane) evolves very slowly, and the substrate may appear to be wettable, notwithstanding a large equilibrium contact angle. In contrast to the apolar films, the non-linear interactions in polar films may remain significant even for the small-amplitude thermal perturbations

The Effect of Phytase Enzyme on the Performance of Broiler Flock (A-Review)

From the last few years, the inclusion of microbial phytase in poultry diets has increased significantly, mainly in response to heightened concerns over phosphorus pollution of the environment and as cheaper means to make phosphorus available to birds from phytate. Phytate is the major form of phosphorus, abundantly found in cereal grains, beans and oilseed meals used in poultry diet but the monogastric animals like poultry birds are unable to utilize this source of phosphorus due to lack of endogenous phytase enzyme. To meet the phosphorus requirements of poultry birds, inorganic phosphates are added to the poultry rations, which lead to the problem of environmental pollution as a large amount of phosphorus is excreted in the manure. Microbial phytase is used as an alternative of this, which has beneficial effects on the growth performance, feed efficiency, protein/amino acid digestibility, energy utilization, mineral retention, and bone growth of broilers due to the direct hydrolytic effects on phytate