Transition of hemoglobin between two tertiary conformations: Determination of equilibrium and thermodynamic parameters from the reaction of 5,5′-dithiobis(2-nitrobenzoate) with the CysF9[93]β sulfhydryl group

The equilibrium constant of the reaction of 5,5′-dithiobis(2-nitrobenzoate) with the CysF9[93]β sulfhydryl group of hemoglobin decreases by 2 to 3 orders of magnitude between pH 5.6 and 9. The reaction is coupled to the ionizations of two groups on the protein. At 25 °C one group has a pKa of 5.31±0.2 when hemoglobin is in its (tertiary) r conformation, typified by the thiolate anion form of CysF9[93]β; this changes to 7.73±0.4 in the (tertiary) t conformation, typified by the mixed disulfide form of the sulfhydryl. The second group ionizes with a pKa of 7.11±0.4 in the r conformation; this changes to 8.38±0.2 in the t conformation. Krt, the equilibrium constant for the r←→t isomerization process, is 0.22±0.06. The standard enthalpy and entropy changes for the isomerization are ΔHo rt=24.2 kJ mol−1 and ΔSo rt=68.8 JK−1mol−1, respectively

Supplier qualification for high value goods and services in Nigeria: A comparison of qualified and non-qualified suppliers

This study set out to understand the capabilities of suppliers of high value products and services in Nigeria. Supplier capability data was collected from almost 500 potential suppliers across 28 product categories. The findings indicate that only a small minority of potential suppliers achieved the required levels of performance and that very few companies have suitable operational capabilities or corporate citizenship behaviour. Furthermore, significant differences were found between service suppliers and product suppliers with regard to performance. The findings suggest that the majority of suppliers of products and services in Nigeria need to improve their operational capabilities and corporate citizenship behaviours or else risk losing their ability to compete in a changing market place with new barriers to entry

An effective method of balancing the workload amongst salesmen

A solution technique is developed which addresses large problems with various numbers and sizes of vehicles and customers in the network. This vehicle routing problem is a further extension of the Multiple Travelling Salesman problem. Given an heuristic solution, limits are set for each component, the violation of which implies that the component is an illegal subtour. An optimal solution is derived using exact algorithms.

THE DEPENDENCE OF SPECTRAL CHARACTERISTICS OF HEART RATE VARIABILITY FROM BODY MASS INDEX IN CONDITIONALLY HEALTHY

In 102 conditionally healthy volunteers aged from 19 to 30 years (average age is 19,53 ± 11 years) the volatility of heart rate variability (HRV) spectral parameters depending on body mass index (BMI) were evaluated. According to WHO recommendations on the calculation and interpretation of BMI were such groups of volunteers: underweight, normal body weight, overweight, obesity I degree, obesity II degree, obesity III degree. Among HRV parameters were evaluated total power (TP, ms2), power of very low frequency (VLF, ms2), low frequency (LF, ms2) and high frequency (HF, ms2) domains of HRV spectrum in the 5-minute intervals of ECG in I standard lead. The data were processed by methods of nonparametric statistics. It was established that spectral characteristics of HRV in volunteers with normal BMI have a high TP with harmonious relations between VLF, LF and HF domains; decreased or increased BMI provokes TP reduction by decreasing power of all domains of HRV (VLF, LF, HF) with a predominance of VLF proportion and this effect increases with the degree of deviation of the parameter