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Biomedical subjects

D Mohan

Publications and source records attributed to D Mohan.

At least 19 recordsLinked to original sources
PubMed2006

Removal of chromium from aqueous solution using cellulose acetate and sulfonated poly(ether ether ketone) blend ultrafiltration membranes.

A process for purifying aqueous solutions containing heavy and toxic metals such as chromium has been investigated. Chromium salts are largely used in various industries including leather-manufacturing industry. Ultrafiltration processes are largely being applied for macromolecular and heavy metal ion separation from aqueous streams. Cellulose acetate and sulfonated poly(ether ether ketone) blend ultrafiltration membranes were prepared by precipitation phase inversion technique in 100/0, 90/10, 80/20 and 70/30% polymer blend compositions and subjected to the rejection of chromium at different concentrations such as 200, 400, 600, 800 and 1000 ppm with a water-soluble macroligand (polyvinylalcohol). Factors affecting the percentage rejection and permeate flux such as pH, concentration of solute, concentration of PVA, transmembrane pressure and composition of blend membranes were investigated. It was found that percentage rejection improved at a pH 6 and a macroligand concentration of 2 wt.%. The transmembrane pressure and concentration of solute also have an effect on the separation and product rate efficiencies of the blend membranes.

Alcohols↗
PubMed2006

Hand surgery on patients who are "high risk" for blood-borne viruses.

There is a risk of transmission of blood-borne viruses (BBV) to health-care workers when performing hand surgery on intravenous drug abusers and other patients known to have BBV. This review summarises methods and procedures that may be employed to help reduce this risk to a minimum. High-risk patients should be identified early and a non-invasive procedure considered. Only experienced staff should scrub and appropriate clothing should be worn. Sharp instrument use should be kept to a minimum and only instrument retraction and suturing should be employed. When possible, wounds should be closed with staples, glue or absorbable sutures. Appropriate steps must be taken to reduce the risk of injuries from sharp bone ends, K-wires and splash exposure during irrigation.

Bandages↗
PubMed2006

Fluorescence quenching of 3-methyl 7-hydroxyl Coumarin in presence of acetone.

Fluorescence quenching of 3-methyl 7-hydroxyl Coumarin in prescence of the acetone is reported here. It was found that the quenching observed was of dynamic nature. It is also observed that quenching of the fluorescence of the indicator had a full reversiblity. As it has a full reversiblity, a novel optical sensor for acetone can be constructed on this quenching.

Acetone↗
PubMed2003

Optical gain characteristics of C 460 and C 450.

Dye concentration dependent gain spectra for Coumarin 460 (C 460) and Coumarin 450 (C 450) in ethanol have been studied using Amplified Spontaneous Emission (ASE) technique under Nitrogen laser (337.1 nm) excitation in the concentration range 10(-2)-10(-5) m/l. The dependence of lasing wavelength and peak gain on concentration have been understood in terms of variation of fluorescence lifetime, which is due to photo-physical processes such as radiation trapping and concentration-quenching. Pump intensity dependence of efficiency is also explained in terms of fluorescence lifetime. A comparison of the stability of the two dyes has also been made on the basis of the functional groups at different positions of the basic coumarin.

Coumarins↗
PubMed2003

Influence of solvent and substituent on excited state characteristics of laser grade coumarin dyes.

Absorption and fluorescence emission of 4 and 7 substituted coumarins viz. C 440, C 490, C 485 and C 311 have been studied in various polar and non-polar organic solvents. These coumarin dyes are substituted with alkyl, amine and fluorine groups at 4- and 7-positions. They give different absorption and emission spectra in different solvents. The study leads to a possible assignment of energy level scheme for such coumarins including the effect on ground state and excited state dipole moments due to substitutions. Excited state dipole moments of these dyes are calculated by solvetochromic data experimentally and theoretically these are calculated by PM 3 method. The dipole moments in excited state, for all molecules investigated here, are higher than the corresponding values in the ground state. The increase in dipole moment has been explained in terms of the nature of excited state and resonance structure.

Coloring Agents↗
PubMed2003

Excited state characteristics of acridine dyes: acriflavine and acridine orange.

The magnitude of the Stokes shift (frequency shifts in absorption and fluorescence spectra) is observed on changing the solvents and further has been used to calculate experimentally the dipole moments (ground state and excited state) of acriflavine and acridine orange dye molecules. Theoretically, dipole moments are calculated using PM 3 Model. The dipole moments of excited states, for both molecules investigated here, are higher than the corresponding values in the ground states. The increase in the dipole moment has been explained in terms of the nature of the excited state. Acriflavine dye overcomes the non-lasing behaviour of acridine orange due to quaternization of the central nitrogen atom.

Acridine Orange↗
PubMed2003

The effect of body mass index and wound irrigation on outcome after bilateral breast reduction.

Thirty patients undergoing bilateral breast reduction by inferior pedicle technique were entered into a prospective, randomized study to determine the effect of unilateral saline wound irrigation and body mass index (BMI) on outcome. Each patient was assessed at 1, 4, and 8 weeks after surgery for wound dehiscence, infection, fat necrosis, and breast comfort by means of a visual analog pain score. The mean patient age was 33 years; mean weight, 67.7 kg; mean BMI, 26.3; and mean weight of breast tissue excised per patient, 1270 g. In 60 breasts there were 13 cases of minor wound breakdown, all of which had healed by 8 weeks postoperatively. Wound irrigation had no significant effect on the rate of T-junction breakdown or on postoperative pain. BMI was associated significantly with wound breakdown (BMI > 26.3, 33% wound breakdown rate; BMI < 26.3, 10% wound breakdown rate; P < 0.05, chi2 test). Patients with a high BMI are more likely to have delayed healing after breast reduction.

Adolescent↗
PubMed2002

Incidence estimates of substance use disorders in a cohort from Delhi, India.

BACKGROUND & OBJECTIVES: There are no reports of incidence studies in the Indian setting on substance use disorders in the general population. This survey-resurvey carried out in metropolis Delhi estimated the incidence rates of substance use disorders. METHODS: A cross-sectional survey was carried out at two points of time with an interval of one year in a representative sample from the general population of metropolis, Delhi. The instrument was precoded, structured and based on DSM III-R operationalised criteria for use of tobacco, alcohol, cannabis and opioids (past one month). Matched data for two points of time were available for 5414 males and 4898 females. RESULTS: In the total cohort, the annual incidence rates (per 100 persons) among males for any drug use, alcohol, tobacco, cannabis and opioids were 5.9, 4.2, 4.9, 0.02 and 0.04 respectively. Among females, incidence of any drug use was 1.2/100 persons. INTERPRETATION & CONCLUSION: Results showed that males have higher incidence for both not-dependent and dependent use for all the drug categories. Females had a higher incidence of dependent tobacco use.

Adult↗
PubMed2002

The co-occurrence of tobacco & alcohol in general population of metropolis Delhi.

BACKGROUND & OBJECTIVES: The association between tobacco and alcohol use behaviours has not been explored in India. This study reports on the co-occurrence of tobacco and alcohol use in a representative general population in metropolis Delhi at two points of time a year apart. METHODS: Matched data on 10,312 individuals from 2937 households above the age of 10 yr were available for survey I and survey II. Among them 5414 were males and 4898 females. The subjects were interviewed by non clinical staff using a structured proforma based on DSM III R criteria on the use of tobacco, alcohol, cannabis and opioids. RESULTS: Among women, use of only tobacco was reported. Among males, the prevalence of use of 'only tobacco', 'only alcohol' and concurrent smoking and drinking was 18.1, 3.3 and 9.6 per cent respectively. Concurrent use was higher in the age group 31-40 yr and dependence higher in the 41-50 yr age group. Both at surveys I and II current smokers had higher percentage of alcohol drinkers compared to tobacco abstainers; dependent smokers had higher percentage of dependent drinkers. The use of alcohol at survey II was higher among tobacco smokers compared to tobacco abstainers identified at survey I (OR = 5.77, 95% CI 4.3-7.7). INTERPRETATION & CONCLUSION: Our results demonstrate a positive correlation between smoking and drinking. The findings lend support to existing evidence suggesting associations between tobacco and alcohol use. Smoking proved to be a powerful predictor of alcohol use. It is suggested that professionals who treat alcoholism should pursue the cessation of smoking among their patients.

Alcohol Drinking↗
PubMed2001

Is first trimester exposure to the combination of antiretroviral therapy and folate antagonists a risk factor for congenital abnormalities?

OBJECTIVES: To assess use of antiretroviral therapy (ART) by HIV positive pregnant women in London since 1994 and the risk of congenital abnormalities associated with multidrug exposure during the first trimester of pregnancy. METHODS: Retrospective multicentre study of medical, obstetric, and paediatric notes of all mother-infant pairs, where the mother was known to be HIV infected before delivery, using a standardised proforma. RESULTS: In this study of 195 mother-infant pairs, use of ART during any stage of pregnancy increased from 33.3% in 1994 to 92.5% in 1999 (p=0.01, trend). First trimester exposure increased from 0% in 1994 to 27.5% in 1999 (p=0.00045, trend). Congenital malformations were observed in nine infants (4.6%). Compared with infants not exposed to ART or folate antagonists during the first trimester (n=148), exposure to both ART and folate antagonists during the first trimester (n=13) was associated with an increased risk of congenital abnormalities (4% v 23.1%; OR 7.10, 95% CI 1.5, 34.2). No malformations were observed in the 34 children exposed to either ART or folate antagonists alone during the first trimester. CONCLUSION: An increasing number of HIV infected women conceived while on ART. Although there is no evidence of teratogenicity caused by ART if given alone during the first trimester, exposure to the combination of ART and folate antagonists was associated with a significantly higher risk of congenital abnormalities in this cohort.

Abnormalities, Drug-Induced↗
PubMed2001

A rapid assessment study on prevalence of substance abuse disorders in metropolis Delhi.

BACKGROUND & OBJECTIVES: No studies in India have attempted to identify in the general population a 'dependent drug user' based on clinically used diagnostic criteria. This two point survey estimated the prevalence of substance use disorders and the change in the trends of drug use after a period of one year in metropolis Delhi. METHODS: A total of 72 colonies in five types of housing clusters were surveyed. The head of the household (HOH) was interviewed only for collecting information about family members (above 10 yr) on an instrument based on the DSM III R operationalised criteria. Trained non medical interviewers administered the precoded instrument to 6004 and 5599 HOH in the first and second surveys respectively. RESULTS: In the first survey, the prevalence of tobacco, alcohol, cannabis and opioids use among males was 27.6, 12.6, 0.3 and 0.4 per cent respectively. The rates were highest in resettlement clusters followed by urban villages, unauthorized, regularized and in 'others' clusters. The use rates remained unchanged during the re-survey. Dependent use (any drug) increased in the resettlement clusters only during the re-survey. INTERPRETATION & CONCLUSION: The results highlight that it is the legal drugs viz., tobacco and alcohol that could pose higher health and social consequences, both short and long term. The situation of illicit drug use (heroin) was higher in the resettlement clusters and urban villages. Need based programmes have to be evolved and executed to keep the drug dependent population stable. The rapid survey technique can be useful in developing countries like India, where resource crunch for survey research is acute. This technique is less costly, quicker to perform and can supplant traditional self-report methodologies.

Adolescent↗
PubMed2000

Dosimetric comparison of pre-planned and or-planned prostate seed brachytherapy.

PURPOSE: To compare the dosimetry of the traditional two step procedure (volume study + treatment planning several weeks later) with that of an OR-based single procedure in which these two steps follow one another immediately. Computer generated treatment plans were used in both procedures. METHODS AND MATERIALS: Several dosimetric parameters relating to target coverage were obtained from dose volume histograms of CT-based evaluation plans developed either 1 or 3 days following seed implantation. A total of 113 patients with early stage (T1C, T2A) prostate cancer were used for this retrospective study. RESULTS: The fraction of target (prostate) covered by the prescription dose (144 Gy), 90% of the prescription dose (115 Gy), and the dose encompassing 90% of the target in the evaluation plan were all statistically significantly improved for OR-based plans compared to pre-planned cases. CONCLUSION: In our hands, there is a small but significant improvement in dose coverage of the prostate when the ultrasound volume study and treatment planning are combined into a single procedure.

Brachytherapy↗
PubMed2000

Burn properties of fabrics and garments worn in India.

A full-scale human form dummy was designed for studying the burning of common dress assemblies (i.e. combination of garments) worn in India. The dummy was made in eight parts; each made of a steel shell filled with water so as to replicate properties of skin-tissue combination. Four thermocouples were fixed on the dummy for measuring torso, neck and face temperatures. The dummy was clothed separately in three women's dress assemblies (saree, salwar-khameez and nightgown) and men's dress assemblies (kurta-pyjama, shirt-pant and lungi), and ignited at the feet by a flat flame. The tests showed that loose fitting garments burnt easily. Once completely burnt, all dress assemblies result in third degree burns over most of the body. The burning process of synthetics is radically different from cottons or cotton-polyester blends. However, flame duration and temperatures produced on the skin are not radically different, suggesting that on the whole synthetics are no worse than cotton garments. Thick garments, such as, jeans and khadi, do not ignite easily and are inherently safer than similar garments made of light fabric. The studies show that results of standard flammability tests using single fabric strips do not correlate with the burning observed in garments as part of a dress where multilayering is common. Standards/codes for fire safety of garments and garment-dress assembly combinations need to be evolved to adequately address their fire safety.

Clothing↗
PubMed2000

Development of an ergonomic evaluation facility for Indian tractors.

The design of tractors manufactured in low-income countries like India has not changed much in the past two decades, especially from an ergonomic point of view. Moreover, in these countries tractors are used for transportation purposes in addition to farming operations. Therefore, the design criteria for these tractors need to be different from those in high-income countries. This paper describes the development of an ergonomic facility for improvement of tractor design. An ergonomic evaluation facility has been developed consisting of a work place envelope for the Indian population, a layout measuring device and an ergonomic rig. This facility can be used for comparative evaluation of the display and control layouts of different tractors in order to develop an optimum layout. The ergonomic rig has the facility to simulate the improved layout for subjective evaluation.

Agriculture↗