Current-voltage characteristics influenced by the nanochannel diameter and surface charge density in a fluidic field-effect-transistor.

The nanochannel diameter and surface charge density have a significant impact on current-voltage characteristics in a nanofluidic transistor. We have simulated the effect of the channel diameter and surface charge density on current-voltage characteristics of a fluidic nanochannel with positive surface charge on its walls and a gate electrode on its surface. Anion depletion/enrichment leads to a decrease/increase in ion current with gate potential. The ion current tends to increase linearly with gate potential for narrow channels at high surface charge densities and narrow channels are more effective to control the ion current at high surface charge densities. The current-voltage characteristics are highly nonlinear for wide channels at low surface charge densities and they show different regions of current change with gate potential. The ion current decreases with gate potential after attaining a peak value for wide channels at low values of surface charge densities. At low surface charge densities, the ion current can be controlled by a narrow range of gate potentials for wide channels. The current change with source drain voltage shows ohmic, limiting and overlimiting regions.

Maximizing ion current rectification in a bipolar conical nanopore fluidic diode using optimum junction location.

The ion current rectification has been obtained as a function of the location of a heterojunction in a bipolar conical nanopore fluidic diode for different parameters to determine the junction location for maximum ion current rectification using numerical simulations. Forward current peaks for a specific location of the junction and reverse current decreases with the junction location due to a change in ion enrichment/depletion in the pore. The optimum location of the heterojunction shifts towards the tip with base/tip diameter and surface charge density, and towards the base with the electrolyte concentration. The optimum location of the heterojunction has been approximated by an equation as a function of pore length, base/tip diameter, surface charge density and electrolyte concentration. The study is useful to design a rectifier with maximum ion current rectification for practical purposes.

PCR-SSCP analysis of leptin gene and its association with milk production traits in river buffalo (Bubalus bubalis).

Leptin gene has been found to be associated with various economic traits including milk production and fat quality in dairy animals. In the present study, we investigated genetic variations in intron 1 region of leptin gene in riverine buffaloes (Bubalus bubalis) using polymerase chain reaction-single strand conformation polymorphism (PCR-SSCP) and sequencing methods and associated them with milk traits. The study revealed three SSCP variants A, B and C among a total of 301 buffaloes from nine breeds. The frequency of variant C was found invariably high among all the breeds except in Marathwada buffalo. Variant A was found to be absent in Chilika, Nili-Ravi, Nagpuri and Pandharpuri breeds and also had the lowest frequencies in Mehsana, Jaffarabadi, Murrah and Toda breeds. Sequencing of SSCP variants revealed a total of five polymorphic sites, with three haplotypes. Statistical analysis revealed significantly high fat percentage at 150 days in SSCP variant B in Mehsana buffaloes. However, the associations of SSCP variants of leptin gene with total milk yield, 305 days milk yield and total fat yield were found to be non-significant. The present study is the first report on association analysis of leptin gene polymorphisms with milk production and milk quality traits in river buffalo.

Reference Values for the Cross Sectional Area of Normal Tibial Nerve on High-resolution Ultrasonography.

Aim: The aim of the study was to establish reference values for the cross-sectional area of the tibial nerve on high-resolution ultrasonography and to investigate the relationship between the cross-sectional area of the tibial nerve and subject's age, gender, height (in cm), weight (in kg) and body mass index. Methods: Two hundred subjects of either gender and over 18 years of age with no history of peripheral neuropathy or trauma to the lower limb were evaluated with high-resolution ultrasonography. Mean cross-sectional areas of tibial nerves were measured at two different levels in both lower limbs, first at 1 cm below the bifurcation of the sciatic nerve into tibial and common peroneal nerves (level I) and the second at 1 cm superior and posterior to the medial malleolus (level II). Results: The mean cross-sectional area measured at level I (0.196 + 0.014 cm2) was larger than the one measured at level II (0.111 ± 0.011 cm2). A positive correlation was found between the mean cross-sectional area and height, weight, and body mass index (p <0.05). Women had smaller cross-sectional areas of the tibial nerves than men at both sites. In addition, no significant relationship was found with the age of the subjects (p >0.05). Conclusion: The established reference values of the cross-sectional area of the tibial nerve will aid in early diagnosis of peripheral neuropathy.

The humble wrist pain could be "early" tuberculosis and a high index of suspicion may help nip it in the bud: A case report.

Osteoarticular tuberculosis of the wrist is a very rare subset of skeletal Tuberculosis. Diagnosing the tuberculosis wrist in its early stage poses a major challenge to the clinicians because of its atypical and vague presentations and a close resemblance to many relatively benign pathologies. Clinicians from developed parts of the world having less exposure to the myriad forms of osteoarticular tuberculosis are more likely to miss it. We hereby report one such case who presented with wrist pain of short duration, which after thorough examination and investigations, turned out to be tuberculous. It was successfully managed with anti-tuberculosis drugs alone without any debridement or synovectomy. Familiarity with the clinical profile of this entity, in its early stages, is valuable for primary care physicians, rheumatologists, internal medicine specialists, and orthopaedicians alike, who may confuse it with one of the many more common inflammatory, degenerative, or traumatic causes of wrist pain. Within normal range or near normal erythrocyte sedimentation rate and C-reactive protein, and normal looking X-ray does not preclude the diagnosis of tuberculosis wrist. The role of a high index of suspicion and a low threshold for getting higher radiological investigation like MRI in non-responding cases of wrist joint pain cannot be overstated.

Reference values for the cross-sectional area of the normal sciatic nerve using high-resolution ultrasonography.

AIM: High-resolution ultrasonography is a new and promising technique to evaluate peripheral and spinal nerves. Its validity as a diagnostic tool in neurological diseases has been demonstrated in adults. The aims of study were to establish the reference values for the cross-sectional area of the normal sciatic nerve on high-resolution ultrasonography, and to determine the relationship between the cross-sectional area of the normal sciatic nerve and the subjects' age, gender, height (in cm), weight (in kg), and body mass index. MATERIAL AND METHODS: Two hundred subjects of both genders and above 18 years of age were studied with high-resolution ultrasonography. The subjects had no history of peripheral neuropathy or trauma to the lower limb. The cross-sectional areas of the normal sciatic nerves were obtained at two different levels in both lower limbs. The mean cross-sectional areas of the sciatic nerves were measured at two different levels, one located at 1 cm above the bifurcation of the sciatic nerve into the tibial and common peroneal nerves, and the other 4 cm above the bifurcation of the sciatic nerve into the tibial and common peroneal nerves. RESULTS: A positive correlation of the mean cross-sectional area was established with height, weight, and body mass index. Women had smaller cross-sectional areas of the normal sciatic nerves than men at both measuring sites. No significant relationship was established with the age of the subjects. CONCLUSIONS: The established reference values of the cross-sectional area of the sciatic nerve can facilitate the analysis of pathological nerve conditions.

Reference values for the cross-sectional area of normal radial nerve at two levels using high-resolution ultrasonography.

AIM OF THE STUDY: High-resolution ultrasound is less often used to evaluate the radial nerves. The radial nerve is often involved in entrapment syndromes. The aim of the study is to establish the reference values for the cross-sectional area of the normal radial nerve on high-resolution ultrasonography, and to identify relationships between the cross-sectional area and the subject's age, gender, height, weight, body mass index, and hand dominance. MATERIAL AND METHODS: The study was conducted on 200 subjects of both sexes, between 18 and 75 years of age, who did not have history of peripheral neuropathy or trauma to the upper limb. High-resolution real-time sonographic examination of the radial nerves was performed in both arms at two different levels. Level 1 was taken just proximal to the nerve bifurcation, and level 2 just after the nerve exits the spiral grove. RESULTS: The mean cross-sectional area measured at level 2 (4.3 ± 0.4 mm2) was greater than that measured at level 1 (2.3 ± 0.3 mm2). No significant relationship was seen with age and hand dominance (p >0.05), but the cross-sectional area values at above mentioned levels were larger in males than in females (p <0.05). In addition, the cross-sectional areas of the radial nerves showed a positive correlation with height, weight, and body mass index (p <0.05). CONCLUSION: The established ultrasonographic reference values along with basic clinical data will aid in the diagnosis, response to treatment, and prognostic evaluation of peripheral neuropathies.

High-resolution ultrasonography of the sural nerve in diabetic peripheral neuropathy.

Aim of the study: To study the cross-sectional area, the maximum thickness of the nerve fascicle and the thickness/width ratio of the sural nerve in patients with diabetes mellitus and non-diabetic subjects using high-resolution ultrasonography and to correlate the results with nerve conduction studies. Material and methods: This prospective study was conducted among 60 patients divided into two groups: A and B. Group A consisted of 30 patients >18 years of age with a history of type 2 diabetes mellitus, and Group B consisted of 30 non-diabetic patients >18 years of age. High-resolution ultrasonography was performed using a linear transducer with the frequency of 5-18 MHz in all the patients in the prone position with the transducer placed in a transverse position at the junction of the middle and lower thirds of the calf. Nerve conduction studies were performed using Aleron 201 (RMS) in all the patients. Results: As compared to the control group, the sural nerve in the diabetic group showed increased cross-sectional area, maximum thickness of the nerve fascicle and thickness/width ratio (p <0.05). Nerve conduction studies showed decreased amplitude, increased latency and decreased velocity in the cases as compared to controls (p <0.05). The cross-sectional area, maximum thickness of the nerve fascicle and thickness/width ratio showed statistical significance when compared with amplitude, latency and velocity in the cases as well as controls (p <0.001). Conclusion: This study suggests that high-frequency ultrasound of the sural nerve is a useful tool for evaluating changes typical of peripheral neuropathy in patients with diabetes mellitus.Aim of the study: To study the cross-sectional area, the maximum thickness of the nerve fascicle and the thickness/width ratio of the sural nerve in patients with diabetes mellitus and non-diabetic subjects using high-resolution ultrasonography and to correlate the results with nerve conduction studies. Material and methods: This prospective study was conducted among 60 patients divided into two groups: A and B. Group A consisted of 30 patients >18 years of age with a history of type 2 diabetes mellitus, and Group B consisted of 30 non-diabetic patients >18 years of age. High-resolution ultrasonography was performed using a linear transducer with the frequency of 5­18 MHz in all the patients in the prone position with the transducer placed in a transverse position at the junction of the middle and lower thirds of the calf. Nerve conduction studies were performed using Aleron 201 (RMS) in all the patients. Results: As compared to the control group, the sural nerve in the diabetic group showed increased cross-sectional area, maximum thickness of the nerve fascicle and thickness/width ratio (p <0.05). Nerve conduction studies showed decreased amplitude, increased latency and decreased velocity in the cases as compared to controls (p <0.05). The cross-sectional area, maximum thickness of the nerve fascicle and thickness/width ratio showed statistical significance when compared with amplitude, latency and velocity in the cases as well as controls (p <0.001). Conclusion: This study suggests that high-frequency ultrasound of the sural nerve is a useful tool for evaluating changes typical of peripheral neuropathy in patients with diabetes mellitus.

Magnetic resonance imaging (MRI) evaluation of perianal fistulae with surgical correlation.

AIMS: The purpose of the study was to evaluate the role of Magnetic Resonance Imaging in detection and characterization of perianal fistulae and correlating it with surgical findings. METHODS: Fifty consecutive patients with suspected perianal fistulae having one or more external openings were prospectively selected for MRI evaluation. Previously operated or patients with recurrent perianal disease were excluded from the study. MRI findings were recorded according to "St. James's University Hospital MR Imaging Classification of Perianal Fistulae" and correlated with surgical observations. Finally, comparison between T2-weighted fat saturated and postcontrast T1-weighted fat saturated sequences was done. RESULTS: Amongst the total of 50 patients, per-operative findings confirmed perianal fistulae in 45 patients. The sensitivity and specificity of MRI in correctly detecting and grading the primary tract was found to be 95.56% and 80% respectively; for abscess, it was 87.50% and 95.24% respectively. High sensitivity was also discerned in identification of secondary tract (93.75%), correct localization of internal opening (95.83%) and for correctly detecting the horse-shoeing (87.50%). Our assumption of null hypothesis was accepted on comparing results of T2-weighted fat saturated sequences and postcontrast T1-weighted fat saturated sequences. CONCLUSION: Magnetic Resonance Imaging (MRI) was highly accurate in assessment of surgically important parameters (primary tract and its grading, internal opening, secondary tract, abscess, horseshoeing) of perianal fistulae. Comparison of results of imaging findings on T2-weighted and postcontrast T1-weighted fat saturated sequences were statistically similar, so contrast study can be omitted, particularly while evaluating primary / previously unoperated perianal fistulae.

Effect of gate length and dielectric thickness on ion and fluid transport in a fluidic nanochannel.

We have simulated the effect of gate length and dielectric thickness on ion and fluid transport in a fluidic nanochannel with negative surface charge on its walls. A short gate is unable to induce significant cation enrichment in the nanochannel and ion current is controlled mostly by cation depletion at positive gate potentials. The cation enrichment increases with increasing gate length and/or decreasing dielectric thickness due to higher changes induced in the surface charge density and zeta-potential. Thus, long gates and thin dielectric layers are more effective in controlling ion current. The model without Navier-Stokes equations is unable to correctly predict phenomena such as cation enrichment, increase in channel conductivity, and decreasing electric field. Body force and induced fluid velocity decrease slowly and then rapidly with gate potentials. The effectiveness of ion current control by a gate reduces with increasing surface charge density due to reduced fractional change in zeta-potential.

Groundwater contaminated with hexavalent chromium [Cr (VI)]: a health survey and clinical examination of community inhabitants (Kanpur, India).

BACKGROUND: We assessed the health effects of hexavalent chromium groundwater contamination (from tanneries and chrome sulfate manufacturing) in Kanpur, India. METHODS: The health status of residents living in areas with high Cr (VI) groundwater contamination (N = 186) were compared to residents with similar social and demographic features living in communities having no elevated Cr (VI) levels (N = 230). Subjects were recruited at health camps in both the areas. Health status was evaluated with health questionnaires, spirometry and blood hematology measures. Cr (VI) was measured in groundwater samples by diphenylcarbazide reagent method. RESULTS: Residents from communities with known Cr (VI) contamination had more self-reports of digestive and dermatological disorders and hematological abnormalities. GI distress was reported in 39.2% vs. 17.2% males (AOR = 3.1) and 39.3% vs. 21% females (AOR = 2.44); skin abnormalities in 24.5% vs. 9.2% males (AOR = 3.48) and 25% vs. 4.9% females (AOR = 6.57). Residents from affected communities had greater RBCs (among 30.7% males and 46.1% females), lower MCVs (among 62.8% males) and less platelets (among 68% males and 72% females) than matched controls. There were no differences in leucocytes count and spirometry parameters. CONCLUSIONS: Living in communities with Cr (VI) groundwater is associated with gastrointestinal and dermatological complaints and abnormal hematological function. Limitations of this study include small sample size and the lack of long term follow-up.

The effect of flap parameters on fluid rectification in a microfluidic diode.

We have studied the effect of flap parameters on fluid rectification in a microfluidic diode. We use Navier-Stokes equations and arbitrary Lagrangian-Eulerian formulation to obtain dynamics of fluid flow and motion of the flap. The flap opens during forward flow and seals against a stopper during reverse flow. This allows flow in the forward direction and prevents it in the reverse direction. The rectifier is fluidic analog to a semiconductor diode in function because it rectifies fluid flow. Velocity-pressure (V-P) curves analog to the current-voltage (I-V) curves of the electronic diode has been obtained. The effect of the flap parameters, such as length, thickness, and Young's modulus has been found out. The transient response of the flap and fluid flow under oscillating pressure driven flow has also been obtained.