Square wave voltammetry of concentrated analytes in fully supported solutions – Cd(II)/Cd(Hg) couple in NaNO3 medium

The influence of significant ohmic potential drop on diffusion-controlled peak currents in square wave voltammetry at macroelectrodes can be drastically reduced by appropriate choice of the square wave amplitude. This allows direct determinations of unusual high concentrations. The experimental verification of theoretical predictions and the analytical procedure validation are performed using a static mercury drop electrode and various concentrations of Cd(II) in 0.1 or 1 M NaNO₃. Diffusion coefficients of Cd(II) and apparent standard potentials of the Cd(II)/Cd(Hg) couple in these media are reported.     

Dance training intensity at 11-14 years is associated with femoral torsion in classical ballet dancers

Objective

To examine in a cross sectional study the influence of femoral torsion (FT) and passive hip external rotation (PER) on turnout (TO). Starting age, years of classical ballet training, and current and past dance training intensity were assessed to determine their influence on FT, PER, and TO in pre‐professional female dancers.

Methods

Sixty four dancers (mean (SD) age 18.16 (1.80) years) were recruited from four different dance training programmes. They completed a dance history questionnaire. FT was measured using a clinical method. PER was measured with the subjects prone, and TO was measured with the subjects standing.

Results

Mean TO was 136°, mean unilateral PER was 49.4°, and mean FT was 18.4°. A positive correlation was observed between PER combined (PERC) and TO (r  =  0.443, p<0.001). A negative association was found between FT combined (FTC) and PERC (r  =  −0.402, p  =  0.001). No association was found between starting age or years of classical ballet training and FTC, PERC, or TO. Dancers who trained for six hours a week or more during the 11–14 year age range had less FT than those who trained less (mean difference 6°, 95% confidence interval 1.4 to 10.3). Students currently training for longer had higher levels of TO (p<0.001) but comparable PERC and FTC.

Conclusion

FT is significantly associated with PERC. Dancers who trained for six hours a week or more at 11–14 years of age had significantly less FT. FTC had a significant influence on PERC, but no influence on the execution of TO.     

下颌骨角全层截骨加下颌骨外板劈除行方形脸改型术

目的 寻求一种新的更有效的方形脸改型术式.方法 对68例(年龄21～40岁,女65例,男3例)方形脸求术者用高速涡轮气钻和骨凿实施了口内入路下颌角全层三角形截骨加下颌外板劈除术,咬肌肥大者同时行咬肌内层切除术,颊部丰满者则行部分颊脂垫摘除.结果 使用高速涡轮气钻和骨凿截除全层下颌角和劈除下颌外板极为容易.56例3～24个月术后随访,双下颌角间距明显缩小,脸型呈椭圆.无下颌不对称、下颌意外骨折.侧方轮廓自然.结论 下颌角全层截骨加下颌外板劈除不仅可有效缩小下颌正面宽度,而且还能改善下颌侧方轮廓,是方形脸改型的一种有效术式.     

Determination of dipyridamole in pharmaceutical preparations using square wave voltammetry

An analytical methodology using square wave voltammetry (SWV) at a hanging mercury drop electrode (HMDE) was developed for the quantitative determination of dipyridamole (DIP), a drug used for the treatment of several cardiovascular diseases, in pharmaceutical tablets and injections of Persantin^® in phosphate buffer (pH 3.0; 0.1 M). After optimization of the parameters for SWV, analytical curves were obtained for application in the range of 1.28 × 10⁻⁶ M to 7.02 × 10⁻⁶ M. It was found a detection limit (DL) of 1.88 × 10⁻⁸ M (9.50 ng/ml). The repeatability and the reproducibility of the method were determinated by successive measurements of DIP solutions on the range of the analytical curve with a coefficient variation of 0.97% (n = 5) and 1.15%, respectively. The apparent recoveries were obtained by the IUPAC recommended procedure using the second reduction peak. Recoveries obtained by SWV were compared with the UV–vis spectrophotometric method. It was found that the determination of DIP in Persantin^® tablets gave a mean value of 75.6 ± 0.4 mg (100.8%) and 68.9 ± 0.3 mg (91.8%) for SWV and UV–vis spectrophotometry, respectively. In the case of injections, it was found 10.4 ± 0.1 mg (103.4%) and 9.9 ± 0.2 mg (99.9%) for SWV and UV–vis spectrophotometry. Both apparent recoveries for the two types of formulations are in good accordance with the declared value of 75 mg (tablets) and 10 mg (injections).     

Determination of the antibiotic drug pefloxacin in bulk form,tablets and human serum using square wave cathodic adsorptive stripping voltammetry

A simple, rapid, reliable and fully validated square wave cathodic adsorptive stripping voltammetric procedure has been developed for the determination of the antibiotic pefloxacin drug in bulk form, tablets and human serum, based on its electrochemical reduction at a hanging mercury drop electrode. The Britton–Robinson buffer of pH 7.0 was found to be reasonable as a supporting electrolyte for assay of the drug. Pefloxacin drug, at the optimized conditions, showed a single 2-electron well-defined peak at −1.07 V (versus Ag/AgCl/KCl_s) using an accumulation potential of −0.40 V. This peak may be attributed to the reduction of the C=O group. A mean recovery of 99.54%±0.23 and a detection limit of 1.65×10⁻¹⁰ M pefloxacin were achieved. After being validated, the proposed procedure was successfully applied for the determination of the drug in tablets and human serum with mean recoveries of 99.57±0.48 and 98.55±0.78%, respectively. A detection limit of 4.50×10⁻¹⁰ M was achieved for the determination of the drug in human serum. Results of the proposed procedure were comparable with those obtained by reported methods.     

Factors affecting falling by older psychiatric inpatients

A search via the literature and two new studies for factors predictive of falling by psychiatric inpatients 50 years and older revealed the following. Comparison in an initial study of patients who had fallen with control patients who had not fallen demonstrated little clearcut difference in regard to possible effects of 64 variables. A second, larger study showed that patients who fell did not differ significantly from the general population of hospital inpatients 50 and older in regard to age, sex, particular hospital unit, or use of tricyclic antidepressants and neuroleptics.     

舞蹈作为学校体育课程教学新内容的可行性研究

采用问卷调查法,进行学生对舞蹈喜欢程度,舞蹈和体育两者之间关系的认同,舞蹈在锻炼身体所起作用等方面的 调查.通过 x2检验进行多组差异显著性检验,发现了舞蹈作为体育教学内容的可行性,提出了自己的想法和建议.     

Effect of inspiratory flow waveform on work on endotracheal tubes: a model analysis

Objective: This model analysis aimed to predict the impact of different inspiratory flow waveforms, i. e., constant, sinusoidal, and two linearly decreasing flows, on the resistive work (Wres) performed on endotracheal tubes. Design: Model analysis. Results: Model analysis predicts that: (i) minimal Wres is obtained with the constant flow; (ii) for any given tidal volume/inspiratory duration (Vt/Ti, mean inspiratory flow), Wres increases with decreasing tube size; (iii) for any given inspiratory flow waveform, Wres increases with increasing Vt/Ti, being lowest with constant flow. Conclusions: These findings have major clinical implications: at any given ventilator setting, not only the size of the endotracheal tube but also the inspiratory flow waveform must be taken into account to interpret the values of Wres and hence of the total work of breathing. Received: 23 July 1998 Final revision received: 4 December 1998 Accepted: 18 February 1999     

A Longitudinal study of body composition and basal metabolic rate during pregnancy in a black population of Kinshasa, Democratic Republic of Congo (RDC)

Objective

A longitudinal study of body composition and basal metabolic rate during pregnancy in a black population of Kinshasa.

Materials and methods

Body composition and basal metabolic rate were determined by bioimpedance, and energy intake was evaluated using the 24 h recall method at 20, 34 and > 37 weeks of gestation in 76 black, Congolese women. The subjects had to be healthy, and to deliver term, singleton infants after a normal pregnancy.

Results

At 20 weeks of pregnancy, the 76 women, aged 28.5 ± 6.4 years, had a body weight of 61.1 ± 7.7 kg, a body mass index of 23.0 ± 3.8 kg/m², a fat mass of 36.6 ± 6.8% and a basal metabolic rate of 1399 ± 84 kcal/24 h. Subsequently, increases in body weight (+6.5 kg), fat-free mass (+ 5.1 kg), body water (+4.4 l) and basal metabolic rate (+297 kcal/24 h) (P < 0.0001) were observed. The increase in fat mass (+1.4 kg) was less pronounced. Energy intake was stable.

Conclusion

Changes in body composition during pregnancy in Congolese black women are comparable to those reported in other populations. Pre- and per-gravidic fat mass is higher in congelese women than in Caucasian women.