Based on thermodynamic principle, the critical relative humidity of electrolytes is closely related to their solubility. The authors explored the relationship theoretically and calculated critical relative humidity of 21 electrolytes from their solubility in the light of Raoult's law and extended Wilson model. The results indicate that the critical relative humidity values calculated by Raoult's law can not accord with the reported ones and there is a systematic error in the high concentration range; while these calculated by extended Wilson model are comparable to the reported ones.
Electrolytes ; chemistry ; Humidity ; Models, Chemical ; Solubility

OBJECTIVETo optimize the synthetic procedure of S-(+)-rivastigmine hydrogentartrate which was known as an agent for the treatment of Alzheimer disease.

METHODSS-(+)-rivastigmine hydrogentartrate was synthesized by using 1-(3-hydroxyphenyl)ethanone as the starting material via oximation, reduction and N-methylation to produce the key intermediate 3-1-dimethylaminoethylphenol, which finally reacted with N-ethyl-N-methylcarbamoyl chloride. The enantiomers were resolved with di-(+)-p-toluoyl-D-tartaric acid, and the title compound was prepared by mixing S-rivastigmine base with L-(+)-tartrate.

RESULTSThe total yield of S-(+)-rivastigmine hydrogentartrate was 4.17%.

CONCLUSIONThe materials in this procedure are all commercially available. The reaction conditions are mild and total yield is high.

Cholinesterase Inhibitors ; chemical synthesis ; chemistry ; Models, Chemical ; Molecular Structure ; Phenylcarbamates ; chemical synthesis ; chemistry ; Rivastigmine ; Stereoisomerism

The stochastic profile of variability of biochemical oxygen demand (BOD) and dissolved oxygen (D0) in the Han River has been considered with Streeter-Phelp's equation. According to the nature of the Han River, the BOD removal coefficient, K1, and the reaeration coefficient, K2 values, were calculated at an average of 0.157 and 0.97 respectively at 20 degrees C in the spring. Where the levels of BOD would be high in relation to the standard of water quality, the treatment for sewage and industrial wastes from tributaries of Seoul City should be performed with proper efficiency. Before 1985 plants with 90% efficiency should be installed at every outlet of the tributaries. The level of DO is not a relevant parameter to assess the pollution in the Han River. The description of the oxygen profile of the Han River also suggests monitoring points for inspection of water quality.
Fresh Water/analysis* ; Korea ; Models, Chemical ; Oxygen/analysis* ; Water/analysis* ; Water Pollution, Chemical/analysis

Goreisan, a well-known hydrostatic modulating formulation, is used clinically in the treatment of edematous disorders. In this study, in order to clarify hydrostatic modulation in the intestine, we analyzed the effect of Goreisan in an experimental diarrhea model created with the single oral pretreatment of magnesium sulfate in mice. Ninjinto (166mg/kg, p.o.) did not lead to improvements in this model, whereas Goreisan (133mg/kg, p.o.) significantly abated the diarrhea.The warm Goreisan extraction (at 37°C, for 0.5hr) showed anti-diarrheal activity that was significantly stronger than the decoction. On investigating the anti-diarrheal activity of Goreisan by comparing the difference in crude drugs made from Atractylodis Rhizoma (Byakujutsu) and Atractylodis Lanceae Rhizoma (Sojutsu), no distinction between Byakujutsu-Goreisan and Sojutsu-Goreisan was recognized. Atractylodis Rhizoma, Polyporus, Poria, and Cinnamomi Cortex, which were administered singly, showed anti-diarrheal activities, but these were weak in comparison with Goreisan. Concoctions in which either Atractylodis Rhizoma, Polyporus, Poria, Alismatis Rhizoma, or Cinnamomi Cortex were omitted from Goreisan showed decreased anti-diarrheal activity as compared with Goreisan. The anti-diarrheal activity was clearly lower in the concoctions of warm extractions whereby the five kinds of crude drugs were extracted separately, compared with the warm extraction of Goreisan in which all crude drugs were extracted simultaneously.These findings suggest that the anti-diarrheal activity of Goreisan in this model was not dependent on a specific crude drug, it being optimal to extract the five kinds of crude drug simultaneously.
Diarrhea ; Models ; Chemical extraction ; cortex bone disorders ; lower case pea

The relation between the critical radius and the particle size distribution for generalized Ostwald type ripening processes whereby the mass transfer coefficient is modelled by a power law was derived. The critical radius is determined by the growth rate, the mass transfer coefficient and the mass balance, and is independent of whether the limiting stationary growth regime has been obtained.
Computer Simulation ; Crystallization ; methods ; Macromolecular Substances ; analysis ; chemistry ; Models, Chemical ; Models, Molecular ; Molecular Conformation ; Particle Size

To investigate the antitumor mechanism of artemisninin, a flexible docking analysis was used to score all kinds of functions of 11 Qinghaosu derivatives and transferrin with different resolutions. The distances of Asp-63, Tyr-188, His-249, Arg-124 and Lys-296 with Qinghaosu were less than 0.5 nm, separately. Meanwhile, the higher is the activity of Qinghaosu derivatives the higher is the score. Our model explains that Fe2+ is more feasible to react with Qinghaosu, and not involved in other metabolism in presence of transferrin. Docking results unveil that Iron(II)-transferrin increased the cytotoxicity of Qinghaosu derivatives and provide a rational basis for further design and synthesis of novel Qinghaosu derivatives.
Antineoplastic Agents, Phytogenic ; chemical synthesis ; chemistry ; pharmacology ; Artemisinins ; chemical synthesis ; chemistry ; pharmacology ; Catalytic Domain ; Drug Discovery ; Models, Chemical ; Molecular Structure ; Protein Binding ; Transferrin ; chemistry

A naphtha catalytic reforming unit with four reactors in series is analyzed. A physical model is proposed to describe the catalytic reforming radial flow reactor. Kinetics and thermodynamics equations are selected to describe the naphtha catalytic reforming reactions characteristics based on idealizing the complex naphtha mixture by representing the paraffin, naphthene, and aromatic groups by single compounds. The simulation results based above models agree very well with actual operation unit data.
Alkanes ; analysis ; chemistry ; Catalysis ; Chemical Industry ; instrumentation ; methods ; Computer Simulation ; Computer-Aided Design ; Equipment Design ; Equipment Failure Analysis ; methods ; Hydrocarbons, Aromatic ; chemical synthesis ; Models, Chemical

The configurational properties of tail-like polymer chains with one end attached to a flat surface are studied by using dynamic Monte Carlo technique. We find that the probability distribution of the free end in z direction P(R(z)) and the density profile rho(z) can be scaled approximately by a factor beta to be a length independent function for both random walking (RW) and self-avoiding walking (SAW) tail-like chains, where the factor beta is related to the mean square end-to-end distance . The scaled P(R(z)) of the SAW chain roughly overlaps that of the RW chain, but the scaled rho(z) of the SAW chain locates at smaller betaz than that of the RW chain.
Computer Simulation ; Models, Chemical ; Models, Molecular ; Models, Statistical ; Molecular Conformation ; Molecular Structure ; Monte Carlo Method ; Polymers ; chemistry ; Statistical Distributions

PURPOSE: Multiple chemical sensitivity (MCS) is a clinical syndrome representing multi-organ and psychological symptoms caused by chronic exposure to various chemicals in low concentrations. We evaluated the prevalence and related factors of MCS targeting Korean adults using the Quick Environmental Exposure and Sensitivity Inventory (QEESI(c)). METHODS: A total of 446 participants were recruited from Severance Hospital. Participants underwent a questionnaire interview including questions on sociodemographic factors, occupational and environmental factors, allergic diseases, and the QEESI(c). Among them, 379 participants completed the questionnaire and the QEESI(c). According to the QEESI(c) interpretation results, participants were divided into very suggestive (VS) group and less suggestive (LS) group. RESULTS: The estimated prevalence of MCS was higher in allergic patients than non-allergic participants (19.7% and 11.3%, respectively, P=0.04). In the multivariate logistic regression analysis, ages of 30-39 (OR, 2.94; 95% CI, 1.25-6.95) and those of 40-49 (OR, 2.51; 95% CI, 1.02-6.21) were significantly related to MCS compared to those aged less than 30 years. Female sex (OR, 2.16; 95% CI, 1.11-4.18), experience of dwelling in a new house (OR, 2.05; 95% CI, 1.04-4.03), and atopic dermatitis (OR, 1.95; 95% CI, 1.04-3.69) were also significantly related to MCS. However, only age of 30-39 in the allergic group was significant in the stratified analysis. CONCLUSIONS: The estimated prevalence of MCS was higher among allergic patients than non-allergic participants. People with experience of dwelling in a new house and atopic dermatitis were more at risk of being intolerant to chemicals. Further studies to provide the nationally representative prevalence data and clarify risk factors and mechanisms of MCS are required.
Adult* ; Dermatitis, Atopic ; Environmental Exposure ; Female ; Humans ; Logistic Models ; Multiple Chemical Sensitivity* ; Prevalence ; Risk Factors

By using the fuzzy min-max neural network, the quantitative structure-activity relationship (QSAR) of mutagenicity is studied. With the established QSAR model, the mutagenicity is predicted and the results showed that QASR is superior to linear-regression model. Further discussion on the models and the results is presented in this paper.
Algorithms ; Cluster Analysis ; Fuzzy Logic ; Models, Chemical ; Neural Networks (Computer) ; Quantitative Structure-Activity Relationship