Search PubMed⌕ Search

Biomedical subjects

D Pandey

Publications and source records attributed to D Pandey.

9 recordsLinked to original sources
PubMed2001

Nomenclature of magnetic, incommensurate, composition-changed morphotropic, polytype, transient-structural and quasicrystalline phases undergoing phase transitions. II. Report of an IUCr Working Group on Phase Transition Nomenclature.

A general nomenclature applicable to the phases that form in any sequence of transitions in the solid state has been recommended by an IUCr Working Group [Acta Cryst. (1998). A54, 1028-1033]. The six-field notation of the first Report, hereafter I, was applied to the case of structural phase transitions, i.e. to transformations resulting from temperature and/or pressure changes between two crystalline (strictly periodic) phases involving modifications to the atomic arrangement. Extensive examples that illustrate the recommendations were provided. This second Report considers, within the framework of a similar six-field notation, the more complex nomenclature of transitions involving magnetic phases, incommensurate phases and transitions that occur as a function of composition change. Extension of the nomenclature to the case of phases with less clearly established relevance to standard schemes of transition in equilibrium systems, namely polytype phases, radiation-induced and other transient phases, quasicrystalline phases and their transitions is recommended more tentatively. A uniform notation for the translational periodicity, propagation vector or wavevector for magnetic and/or incommensurate substances is specified. The notation adopted for incommensurate phases, relying partly on the existence of an average structure, is also consistent with that for commensurate phases in a sequence. The sixth field of the nomenclature is used to emphasize the special features of polytypes and transient phases. As in I, illustrative examples are provided for each category of phase sequence.

Journal Article↗
PubMed2001

Simple time weighted average level air-monitoring method for sulfur mustard in work places.

A simple air-monitoring method was developed and validated for vesicant sulfur mustard (HD) in the work place at time weighted average levels. XAD-2 adsorbent was used for the collection of HD vapours for 8 h followed by liquid desorption with carbon tetrachloride. The trace level analysis was carried out by gas chromatography-photoionization detection and was confirmed by gas chromatography-mass spectrometric detection in the selected ion mode.

Air Pollutants, Occupational↗
PubMed2000

Novel features of Sr1-xCaxTiO3 phase diagram: evidence for competing antiferroelectric and ferroelectric interactions

Structural and dielectric evidences are advanced to show that the Sr1-xCaxTiO3 (SCT) system undergoes an antiferroelectric (AFE) phase transition in the composition range 0.18</=x</=0.40. Stabilization of the AFE phase, instead of the ferroelectric (FE) phase known for 0<x<0.12, is shown to be intimately linked with the nonpolar antiferrodistortive phase transitions driven by the R and M point instabilities preceding the AFE transition. It is proposed that the disorder and frustration introduced by CaTiO3 substitution in the incipient FE matrix of SrTiO3 leads to the smearing of the varepsilon(')(T) response in SCT for 0.002<x<0.12 akin to dipole glasses and relaxor ferroelectrics.

Journal Article↗
PubMed1998

Comparison of reported symptoms of acute myocardial infarction in Mexican Americans versus non-Hispanic whites (the Corpus Christi Heart Project).

This study examines whether there are differences between Mexican Americans and non-Hispanic whites in reported symptoms of acute myocardial infarction (AMI). The symptoms experienced by patients identified in a community-based surveillance program were examined to determine whether between-group differences existed by ethnicity, gender, and diabetic status. Data were available regarding the symptoms of 589 patients, between the ages of 25 and 74 years, who were hospitalized and diagnosed as either having definite or possible AMI in special care units at 1 of 7 hospitals in Corpus Christi, Texas. The most frequently reported symptoms were chest pain (83.2%), chest pressure or discomfort (67.6%), sweating (64.2%), fatigue (62.6%), dyspnea (60.3%), and arm or jaw pain (58.2%). After adjusting for age, diabetes mellitus, and gender, and relative to non-Hispanic whites, Mexican Americans were more likely to report chest pain, upper back pain, and palpitations, and less likely to report arm or jaw pain. Likewise, relative to men, women were more likely to report fatigue, dyspnea, dizziness, upper back pain, palpitations, and cough, and were less likely to report chest pain. Significant differences were also observed when older patients' symptoms were compared with younger patients' symptoms.

Adult↗
PubMed1998

Association between violent behaviors and substance use among Mexican-American and non-Hispanic white high school students.

PURPOSE: To determine the prevalence of violent behaviors among Mexican-American and non-Hispanic white high school students and to explore the associations between violent behaviors and alcohol and illicit drug use. METHODS: The Youth Risk Behavior Survey was administered to 1786 high school students in a biethnic community in Southeast Texas; 65% were Mexican-American, 26% were non-Hispanic white, and 9% were of another ethnicity. RESULTS: There were no significant ethnic differences in prevalence of drinking alcohol, illicit drug use, fighting, carrying a weapon, or planning or attempting suicide. After adjustment for age, carrying a weapon and fighting were significantly associated with alcohol and illicit drug use, with few exceptions, among the four gender- and ethnic-specific subgroups. However, the relationship between suicide (plans and attempts) and substance use among the four subgroups was less consistent and of much lower magnitude than for carrying a weapon and fighting. CONCLUSIONS: A substantial percentage of adolescents engage in violent behaviors, and fighting and weapon carrying are associated with substance use among both gender and ethnic groups. A systematic and integrated approach to changing the environment and norms of communities is needed to affect change and reduce the morbidity and mortality associated with violent behaviors.

Adolescent↗