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The present work aims to focus on the heat transfer analysis of the peristaltic flow of biviscosity fluid in an annular region between two coaxial flexible tubes with different amplitudes and phases under the influence of a radially varying magnetic field and constant rotation. In this model, the non‐Newtonian biviscosity fluid is flowing through the annulus region between the two concentric inclined tubes. The outer flexible tube is permeable and supposed to satisfy the Saffman slip condition. The governing equations for the considered problem are simplified under the assumptions of a creeping flow and long‐wavelength approximations. Semi‐analytical expressions for the axial velocity and temperature profile are obtained using the homotopy perturbation method. Here, the expressions for shear stress and stream function are also obtained. In this work, the authors discussed the impact of various flow parameters like the Hartmann number, rotation of the frame, permeability parameter, phase difference, amplitude ratios of inner and outer tubes, radius ratio, and inclination angle on the above flow variables. The streamline contour plots are also drawn for the realization of the fluid flow inside the annular endoscopic region. A noticeable result which is drawn from the present study is that phase difference ξ$\xi$ and amplitude ratio ϕ1$\phi _1$ are responsible for reduction and enhancement in temperature and axial velocity of the moving fluid, respectively. It is also found from the present examination that the rise in the strength of the applied magnetic field enhances the transverse fluctuations of peristaltically propagating waves. The comparison of the sinusoidal waveform with the various types of waveforms, such as triangular, trapezoidal, and square waveforms, in the case of a peristaltic endoscope is also discussed. The proposed model may give insights into designing a novel endoscope and decide whether such types of peristaltic endoscopes have exemplary implementations for surgical and mechanical purposes. [ABSTRACT FROM AUTHOR]

This work focuses on the heat transfer analysis of the magnetohydrodynamic peristaltic flow of blood through the gap between two coaxial flexible tubes of different wavelengths. In this model, the non-Newtonian biviscosity fluid is assumed to be blood, which is flowing through the annulus region between the inclined tubes. The governing equations for the considered problem are simplified under the assumptions of a zero Reynolds number and long wavelength approximations. An analytical expression for the temperature is obtained in its closed form, while a semi-analytical solution for the axial velocity of the moving fluid is determined using the homotopy perturbation method. Expressions for various flow variables such as shear stress, volumetric flow rate, pressure rise, and frictional force at the surface of inner and outer tubes are also obtained. In this work, we discussed the impact of various flow parameters like the Hartmann number, Grashof number, heat source, upper limit apparent viscosity coefficient, amplitude ratios of inner and outer tubes, radius ratio, and wavelength ratio on the above flow variables. The streamline contour plots are also drawn for the realization of the flow pattern of the blood inside the endoscope. The comparison of shear stresses for the peristaltic and rigid endoscopes and the validation of the present result with the previously established results are also discussed. A noteworthy observation drawn from the present model is that the pressure gradient enhances for increasing values of wavelength ratio when the wavelength of the inner tube is less than the wavelength of the outer tube, whereas the pressure gradient gets suppressed for increasing values of wavelength ratio when the wavelength of the inner tube is greater than the wavelength of the outer tube. From the present analysis, it is also found that the shear stress τrz of blood is the least for a peristaltic endoscope as compared to the rigid one. Therefore, this study may be applicable to medical practitioners for laparoscopic purposes, as a peristaltic endoscope may be a more appropriate device due to its flexibility than a rigid endoscope. [ABSTRACT FROM AUTHOR]

The present work investigates the creeping peristaltic propulsion of viscid fluid in an annular gap between sinusoidally deforming permeable and impermeable curved tubes of similar shape under the influence of an externally imposed electric and magnetic field. In this model, the outer tube with a permeable wall surface is supposed to satisfy the Saffman slip condition. The flow equations are simplified by the estimation of a large wavelength in comparison with the radius of the external tube. An analytical solution for the axial velocity is obtained in the computational software MATHEMATICA. Graphical analyses are conducted to explore the variations in wall shear stress, velocity, pressure rise, frictional force, and stream function with respect to different emergent parameters, providing insight into the underlying physics of the flow phenomena. An investigation of the effects of the Hartmann number and electric field strength on the flow through a gap between deformable tubes with curved structures has important implications for a variety of engineering applications, including mechanical and biomedical engineering. The streamlines are plotted to discuss fluid trapping and visualize the flow pattern of the viscid fluid inside the curved annular domain. A comparative analysis of fluid transport induced by sinusoidal, triangular, trapezoidal, and square wave shapes is encountered with the help of streamlined contour diagrams. The comparison of pressure gradients in three different models is also discussed to gain insight due to fluid–structure interaction. A gap in the body of recently published literature is filled by the results discussed in this paper. [ABSTRACT FROM AUTHOR]

Background and objective Choice of appropriate antimicrobial agent in treatment of infections is a major problem. Gram negative isolates are notorious for rapid development of resistance. Since the susceptibility profile of various isolates changes rapidly, knowledge about the efficacy of newly introduced drugs is important for clinicians. The objective of this study was to determine the in vitro efficacy of piperacillin/sulbactam (combicin), a beta lactam/beta lactamase inhibitor combination against gram negative rods isolated from various clinical specimens at Armed Forces Institute of Pathology Rawalpindi. Method A total of 497 consecutively isolated Gram negative rods from various clinical samples submitted at AFIP from June 2009 to October 2009 were included in the study. Antibiotic susceptibility of these isolates against piperacillin/sulbactam was carried out by disc diffusion method. Results Of the 497 isolates tested, 362 (72%) were sensitive, 130 (26%) were resistant and 5 (1%) were intermediately susceptible to piperacillin/sulbactam. The most resistant microorganism to this compound was Klebsiella pnuemoniae, as 20/56 (35%) isolates were resistant where as the most susceptible organism was Proteus spp, with 18/20 (90 %) isolates being susceptible to piperacillin/sulbactam. Conclusion The newly introduced agent piperacillin/sulbactam has good overall efficacy against the usual gram negative isolates in our setup. This antimicrobial, however, should be cautiously used as an empirical agent in seriously ill patients suspected of gram negative infections. [ABSTRACT FROM AUTHOR]

Objective To evaluate the in vitro activity of nitrofurantoin against various isolates yielded from urine specimens. Place and duration Department of Microbiology, Armed Forces Institute of Pathology Rawalpindi, from January 2009 through January 2010. Materials and methods A total of 919 urinary isolates (Escherichia coli 690, Klebsiella pneumoniae 62, Klebsiella oxytoca 26, Enterococcus faecalis 54, Enterococcus faecium 18, Enterobacter agglomerans 16, Enterobacter cloacae 4, Acinetobacter baumannii 20, Citrobacter spp 15, Serretia marcesens 14) were cultured from urine specimens during the study period. All the isolates were tested against nitrofurantoin along with other routine antibiotics used for urinary pathogens. Results Out of total 919 urinary isolates, percentages of sensitivities of nitrofurantoin against Escherichia coli, Klebsiella pneumoniae, Klebsiella oxytoca, Enterococcus faecalis, Enterococcus faecium, Enterobacter agglomerans, Enterobacter cloacae, Acinetobacter baumannii, Citrobacter spp, Serretia marcesens were 89.4, 32.3, 15.4, 81.5, 39.0, 43.8, 50, 25, 26.7 and 28.6% respectively. Conclusion Nitrofurantoin is very effective against urinary isolates in-vitro and can be used empirically for uncomplicated urinary tract infections. [ABSTRACT FROM AUTHOR]

Objective: To determine the susceptibility pattern of extended spectrum ß-lactamase (ESBL) producing Gram negative isolates from various clinical specimens., Study Design: Descriptive study., Place and Duration of Study: Microbiology Department, Armed Forces Institue of Pathology, Rawalpindi, from January 2008 to January 2009., Methodology: A total of 308 ESBL producing isolates from various clinical specimens sent to AFIP for culture and sensitivity were identified using standard microbiological techniques and tested for antimicrobial susceptibility. At the same time screening for ESBL production was also done. ESBL production was confirmed by combination disc synergy method. The susceptibility pattern of isolates was then recorded in frequency percentages., Results: Out of the 308 ESBL producing isolates more than 99% were susceptible to carbapenems, 84% to tazobactam/ piperacillin, 81% to sulbactam/cefoperazone, 12% to fluoroquinolones, 13% to cotrimoxazole, 59% to amikacin and 18% to gentamicin. Among the urinary isolates 49% were susceptible to Nitrofurontoin and only 5% to Pipemidic acid., Conclusion: Antibiotic choices in case of ESBL producing isolates are limited and at present only carbapenems can be regarded as treatment of choice. As empirical agents, beta-lactam/beta lactamase inhibitor combinations should be used cautiously for serious infections. Fluoroquinolones showed very poor efficacy. Amikacin can be used alternatively in such cases. Nitrofurantoin is still a good oral agent for treating UTI.