Computational investigations of the mixing performance inside liquid slugs generated by a microfluidic T-junction     

Yuehao Li  Rupesh K. Reddy  Challa S. S. R. Kumar  Krishnaswamy Nandakumar 《Biomicrofluidics》2014,8(5)

Droplet-based microfluidics has gained extensive research interest as it overcomes several challenges confronted by conventional single-phase microfluidics. The mixing performance inside droplets/slugs is critical in many applications such as advanced material syntheses and in situ kinetic measurements. In order to understand the effects of operating conditions on the mixing performance inside liquid slugs generated by a microfluidic T-junction, we have adopted the volume of fluid method coupled with the species transport model to study and quantify the mixing efficiencies inside slugs. Our simulation results demonstrate that an efficient mixing process is achieved by the intimate collaboration of the twirling effect and the recirculating flow. Only if the reagents are distributed transversely by the twirling effect, the recirculating flow can bring in convection mechanism thus facilitating mixing. By comparing the mixing performance inside slugs at various operating conditions, we find that slug size plays the key role in influencing the mixing performance as it determines the amount of fluid to be distributed by the twirling effect. For the cases where short slugs are generated, the mixing process is governed by the fast convection mechanism because the twirling effect can distribute the fluid to the flow path of the recirculating flow effectively. For cases with long slugs, the mixing process is dominated by the slow diffusion mechanism since the twirling effect is insufficient to distribute the large amount of fluid. In addition, our results show that increasing the operating velocity has limited effects on improving the mixing performance. This study provides the insight of the mixing process and may benefit the design and operations of droplet-based microfluidics.  相似文献   

External quality assessment for the RIA of thyroid related hormones: Second phase     

Ajay Kumar  D. H. Shah  M. G. R. Rajan  U. R. Thakare  S. M. Sharma 《Indian journal of clinical biochemistry : IJCB》1992,7(2):159-164

An external quality assessment was conducted to assess the performance of various laboratories for RIA of thhyroid related hormones in two phases. In the first phase thirty five laboratories participated. At the end of first phase a meeting cum workshop was organised to discuss the results of first phase, difficultires faced by the participants and pinpoint the short oming. A second phase was then initiated with an objective of improvement in the performance, if any, where twelve samples from four pools were distributed to twenty four laboratories who participated for the second phase. The overall return of the results increased significantly from 71.8% (1586/2208) for the first phase to 92.4% (732/792) for the second phase. The inter laboratory %CV for T₃, T₄ and TSH were lower during the second phase (30.6%, 19.0% and 31.6% respectively) as compared to those observed during first phase (36.3%, 22.7% and 52.8% respectively). Similarly, there was an improvement in reproducibility of ALTM as %CV for T₃, T₄ and TSH decreased from 6.0%, 9.8% and 13.4% respectively to 4.5%, 4.6% and 8.5% respectively. The individual performances of the participating laboratories viz. bias, variability of bias and imprecision also showed a trend towards improvement as percent laboratories having desirable or acceptable results for T₃, T₄ and TSH increased from 10.7%, 60.7% and 0.0% respectively to 20.8%, 66.7% and 22.2% respectively. External quality assessment thus appears to be beneficial in assessing the performane of a laboratory in comfparison with other laboratories and indeed helps in improving the performance.  相似文献   

Evaluation of urinary abnormalities in urolithiasis patients: A study from North India     

R. Kumar  R. Kapoor  B. Mittal  A. Kumar  R. D. Mittal 《Indian journal of clinical biochemistry : IJCB》2003,18(2):209-215

Metabolic abnormalities were investigated in 44 stone patients with first time (group 1) and 56 with 2 times stone formation (group 2), and in 25 normal individuals. 24hr urine was analysed spectrophotometrically for oxalate, calcium, magnesium, citrate, uric acid, phosphate and creatinine. Hypocitraturia and hyperoxaluria were the common abnormalities in the stone formers. Stone patients had significantly higher urinary oxalate, calcium and uric acid and lower phosphate than normal individuals. Citrate/calcium and magnesium/calcium ratio were significantly high in normal individuals than stone formers. Patients in group 2 excreted significantly higher urinary calcium and lower citrate that patients in group 1. Citrate/calcium ratio was higher in group 1 than group 2. Hypocitraturia, hyperoxaluria, hypercalciuria and increased citrate/calcium and magnesium/calcium ratio seem to be an essential risk factor for stone formation. Patients with recurrent stone formation could be distinguished from patients with first time stone formation on the basis of urinary calcium and citrate.  相似文献   

Serum oestradiol in women with carcinomas of the breast and uterine cervix     

Amitabha Ray  Anil Kumar Bahadur  S. L. Dayalu Naik  Bhuvnesh Kumar Sharma 《Indian journal of clinical biochemistry : IJCB》2001,16(2):199-202

Endogenous oestrogens are thought to be involved in breast cancer, but few studies could show the direct relationship between hormones and pathological process of the disease. In the present study, oestradiol was estimated in the serum of pre-and postmenopausal breast cancer patients along with normal healthy controls and patients with carcinoma of the uterine cervix which is not dependent on oestrogens. Premenopausal patients with breast cancer showed higher levels of oestradiol as compared to premenopausal control women as well as cervical cancer patients. Whereas, no statistically significant differences were observed in serum oestradiol levels amongst postmenopausal groups of breast cancer, cervical cancer and normal women. The result of the study reflects the association of oestradiol as well as its difference in the pathological events of pre and postmenopausal breast cancer.  相似文献   

Status and Interrelationship of Zinc,Copper, Iron,Calcium and Selenium in Prostate Cancer     

Bhupendra Pal Singh  Shailendra Dwivedi  Urmila Dhakad  Ramesh Chandra Murthy  Vimal Kumar Choubey  Apul Goel  Satya Narayan Sankhwar 《Indian journal of clinical biochemistry : IJCB》2016,31(1):50-56

Deficiency or excess of certain trace elements has been considered as risk factor for prostate cancer. This study was aimed to detect differential changes and mutual correlations of selected trace elements in prostate cancer tissue versus benign prostatic hyperplasia tissue. Zinc, copper, iron, calcium and selenium were analysed in histologically proven 15 prostate cancer tissues and 15 benign prostatic hyperplasia tissues using atomic absorption spectrophotometer. Unpaired two tailed t test/Mann–Whitney U test and Pearson correlation coefficient were used to compare the level of trace elements, elemental ratios and their interrelations. As compared to benign prostatic tissue, malignant prostatic tissue had significantly lower selenium (p = 0.038) and zinc (p = 0.043) concentrations, a lower zinc/iron ratio (p = 0.04) and positive correlation of selenium with zinc (r = 0.71, p = 0.02) and iron (r = 0.76, p = 0.009). Considerably divergent interrelationship of elements and elemental ratios in prostate cancer versus benign prostatic hyperplasia was noted. Understanding of differential elemental changes and their interdependence may be useful in defining the complex metabolic alterations in prostate carcinogenesis with potential for development of element based newer diagnostic, preventive and therapeutic strategies. Further studies may be needed to elucidate this complex relationship between trace elements and prostate carcinogenesis.  相似文献   

Astudy on mycobacterial proteins in the serodiagnosis of tuberculosis using ELISA and western blot     

Ajay Kumar  T. A. Venkita Subramanian  Usha P. Sharma 《Indian journal of clinical biochemistry : IJCB》1992,7(2):165-168

Protein fraction termed P₂ was obtained from sonicates of Mycobacterium smegmatis, subjected to ammonium sulphate precipitation. P₂ fraction was further fractionated into 4 fractions (PeakI-IV) by DEAE cellulose ion-exchange chromatography. ELISA was performed on the sera of 104 tuberculous cases and 62 controls, using P₂ fractions Peak I as test antigens. Though the mean ELISA values in tuberculous cases were higher than the controls, no statistically significant difference was found between the two. Antigens P₂, Peak I and IV were tested on Western blots with pooled sera from tuberculous cases as well as controls. P₂ fraction, Peak-I and IV were separated on PAGE-SDS, electroblotted onto nitrocellulose Sheets and the blots were subjected to ELISA. Peak IV appeared as a single band (M.W. 55,000). P₂ fraction exhibited some discriminatory bands on development of blots.  相似文献   

Role of yoga in control of hyperglycemia in middle aged patients of non-insulin dependent diabetes mellitus     

Suresh Chander Jain  Bandana Talukdar 《Indian journal of clinical biochemistry : IJCB》1995,10(2):62-65

The effect of 40 days yoga training in 30 hospitalized non-insulin dependent diabetes mellitus (NIDDM) patients has been investigated after stopping the medication. Blood glucose response to oral glucose load measured as area index total (AIT), glycated haemoglobin (GHb) plasma lipids and lipoproteins measurements before and after yoga training have been compared. Yoga training resulted in a significant improvement in AIT, GHb and plasma triglycerides and cholesterol levels. The data suggest that yoga training along with diet and medical management provides an important metabolic control in NIDDM and may have a role in primary prevention of diabetes mellitus.  相似文献   

Study of adenosine deaminase activity in various arthritic conditions     

R. Kumar  S. B. Pachori  G. K. Senger  Satyanand  L. D. Joshi 《Indian journal of clinical biochemistry : IJCB》1994,9(2):72-74

Aim of present study was to compare the adenosine deaminase (ADA) activity in various types of arthritis conditions with synovial effusion. No. significant difference was observed in ADA activity in serum of control and study groups but results have shown a definite pattern of ADA activity in synovial fluid in various arthritic conditions. The highest value of ADA activity was observed in synovial fluid of patients with tubercular arthritis followed by rheumatoid, septic, osteo and post traumatic arthritis. Thus measurement of ADA activity in synovial fluid can be used as a parameter of differential diagnosis of arthritis specially tubercular in initial stages.  相似文献   

Finite-time stability and stabilization results for switched impulsive dynamical systems on time scales     

Vipin Kumar  Mohamed Djemai  Michael Defoort  Muslim Malik 《Journal of The Franklin Institute》2021,358(1):674-698

In this article, we study the finite-time stability (FTS) and finite time stabilization problems for a class of switched impulsive systems evolving on an arbitrary time domain. This problem is formulated using time scale theory where the time domain can be continuous, discrete, union of disjoint intervals with variable gaps and variable lengths or any combination of these. Using common Lyapunov-quadratic and Lyapunov-like functions, we establish sufficient conditions to ensure the FTS results. Further, to solve the stabilization problem, we design state feedback controllers. We have illustrated the effectiveness of the obtained analytical results though numerical examples.  相似文献   

Effect of Vitamin E on sP-Selectin Levels in Pre-Eclampsia     

Wangkheimayum S  Kumar S  Suri V 《Indian journal of clinical biochemistry : IJCB》2011,26(2):169-171

P-selectin, a cell adhesion molecule is elevated in many inflammatory conditions including preeclampsia which is characterized by generalized endothelial dysfunction and vasoconstriction presumably due to free radicals or mediators released by defective placentation. Vitamin E has been documented to protect cell membranes from oxidative damage and also decrease platelet aggregation. The role of vitamin E in pre-eclampsia is contradictory and hence the study was undertaken. Soluble P-selectin was measured by ELISA and Vitamin-E levels in plasma was estimated spectrofluorometrically. In our study the effect of supplementation of 400 IU/day of Vitamin E (a-tocopheryl acetate) to patients of pre-eclampsia showed significant decreased levels of soluble P-selectin by 2nd week as compared to patients given placebo (P = 0.005). In this short period of study no direct correlations were observed between Vitamin E or P-selectin levels with blood pressure as well as with proteinuria. Future studies may focus on the effect of a-tocopheryl acetate or the phosphate form of Vitamin-E, recently proposed to be the more active form on other inflammatory markers like IL-6, an important stimuli of P-selectin release in pre-eclampsia.  相似文献