[Analysis on the rationality of input and output of occupational health funds in an iron and steel enterprise].

Objective: To analyzes the various occupational health investment and occupational health output of a steel enterprise, and propose a reasonable occupational health investment plan for this enterprise. Methods: In march 2016, various occupational health input and output data of various branches of an iron and steel company in 2015 were collected, and the efficiency of occupational health inputs and outputs of each branch was evaluated using data envelopment analysis (DEA) , and the branches with non-optimal efficiency were adjusted to propose a reasonable occupational health investment plan. Results: Among the branch plants investigated by this steel company, the occupational health input-output efficiency values of ironmaking north plant, power plant, hot rolling plant and stainless steel plant were 1, while the occupational health input-output efficiency of gas making plant, cold rolling plant, metallurgical furnace charge plant, coking plant, ironmaking south plant and long product plant were not the best, and the cold rolling plant has the lowest efficiency value of 0.759. For the cold rolling plant, only the parameters of acid rolling plant satisfy α=1 and s(-)=0, s(+)=0, while the remaining four workshops do not meet. After adjusting the inputs of each part according to the parameters, the occupational health output of the remaining four workshops can reach 1.7044, 2.0238, 1.3152 and 1.2136 times of the current workshop, respectively. Adjustment plans for other branch factories with unreasonable investment structures are also presented in the corresponding tables. Conclusion: The occupational health investment structure of the ironmaking south plant and other branches in this steel enterprise is unreasonable, and the adjustment using data envelopment analysis can maximize the benefits of its occupational health output.

[Analysis of occupational health input-output of a iron mine in Hebei province].

Objective: To explore the relationship between input and output of occupational health funds, and to provide basis for relevant departments to make decisions. Methods: In September 2018, a state-owned iron ore in Hebei Province (mining history of more than 10 years, which can represent the general type of iron ore) was selected as the research object. Through the investigation and collection of enterprise general situation, occupational health input, loss and output related indicators, the iron mine occupational health expenditure input-output table and model were established, and the digital relationship between the investment and output was solved by MATLAB software. Results: The labor consumption in the departments of underground mining, open pit mining, crushing and rock discharging, transportation, tailings and mineral processing (taking labor wages as reference) were 756.46, 1.281.78, 987.61, 1 570.71, 50.956 and 18.9116 million yuan/year respectively. The output value of each sector is 11 207.19, 18 989.95, 15 176.40, 25 294.00, 7.704.94 and 280.1797 million yuan/year respectively. The ratio of health input to total output was 0.004 5, and the ratio of occupational health input to output was 1/0.046. Conclusion: The input-output table model of occupational health in iron mine can reflect the relationship between input and output of occupational health funds. The input situation of the coal mine is poor, and the input does not bring obvious occupational health benefits.

EFFECT OF NAC ON MOUSE GV OOCYTE SURVIVAL AND SUBSEQUENT EMBRYONIC DEVELOPMENT FOLLOWING VITRFICATION.

BACKGROUND: Oocytes that survive cryopreservation may accumulate ROS which are known to bring harmful effects on embryonic development. NAC is an antioxidant which can be a supplement to reduce oxidative stress. However, whether NAC can improve the developmental competence of vitrified GV-oocytes remains unclear. OBJECTIVE: The study was to investigate the effect of NAC on subsequent embryonic developmental competence of mice vitrified GV-oocytes. MATERIALS AND METHODS: This study compared the effects of different concentration of NAC on the cleavage and blastocyst rates of mice vitrified GV-oocytes. Then the effects of NAC on mitochondria distribution, ROS level and embryonic development of vitrified oocytes were tested. RESULTS: ROS activity of vitrified oocytes was significantly annihilated and mitochondrial distribution pattern was improved by 1.5 mM NAC (P<0.05). NAC supplementation throughout vitrification/warming and IVM media significantly improved the developmental competence of vitrified oocytes. CONCLUSION: Supplementation of NAC could partially overcome the damages by vitrification and improve the development ability of mice vitrified GV-oocytes.

[Calcium ion-selective miroelectrodes for measurement of free calcium in saliva]

In this paper, the free calcium concentration in saliva was measured and evaluated by the neutral carries ion-selective microelectrodes.The statistical results showed that there was no significant difference (the groups of all,P>0.05) between children and adult,between male children and female one,between caries-free and caries-active,and between interval of two weeks.The results suggested that caries might be no direct relation to the calcium concentration in children physiological saliva. Calcium ion-selective microelectrodes seems to be a good method for measuring free calcium in oral micro-sample fluid.

[Proteolytic phenomenon in enamel caries]

The proteolytic phenomenon in enamel caries has been investigated from three directions.Three kinds of proteolytic enzymes,papain,trypsin and collagenase have been used for treating enamel both in vitro and in vivo to observe their effect on the development of artificial enamel caries and demineralization of upper central incisors of thirty young persons.The results showed that the depth of the artificial caries was not increased after enzyme treatment.The calcium content of the demineralizing solution is also not increased after enzyme treatment.when the enamel powder of human beings was treated at first by natural plaque fluid and then by demineralizing liquid,no difference was observed between the data of experimental and control groups.Therefore,the results of this study does not support Gottleib's proteolytid theory of caries,especially in case of enamel ones.

Multibacterial artificial plaque. A model for studying carious process.

A multibacterial artificial plaque was established in vitro on enamel slabs incubated in mixed culture of Streptococcus sanguis, Streptococcus mutans (serotype c), Streptococcus salivarius, Lactobacillus casei and Actinomyces viscosus. Typical structure same as natural plaque was seen under microscope. The caries-like lesion produced under the plaque was observed in enamel sections. The lesion was similar in appearance to natural ones under optic and scanning electron microscopes. The acids produced in both culture media and artificial plaque were similar in composition and type to those produced in natural plaque after sugar attack. It is suggested that this kind of plaque model may be useful in studying carious process in vitro, because it is easily controlled either by changing the composition of bacteria or by adding different kinds of nutrient in the media. Moreover, the results will be easier to explain than those produced in natural ones.

Dynamic analysis of organic acids in extracellular fluids of human dental plaques.

Organic acids in unstimulated saliva and extracellular fluids of dental plaques from 12 middle school students were measured by ion-chromatography. The acids in the plaques were analyzed before and 5-10, 30-35, 60-65 minutes after rinsing with 10% sucrose solution. The differences of the acids between the extracellular fluids of resting plaques and unstimulated saliva were significant. In the extracellular fluids of plaques, the concentration of high pK acids, i.e. acetic and propionic acids was higher than that of low pK acids i.e., lactic and formic acids before and after sucrose rinse. The relations of time-dependent changes between the ratio of low pK to high pK acids and pH were observed in the extracellular fluids of plaques after sucrose rinse. No significant difference of lactic acid concentrations was found between the caries-active and caries-free subjects 30-35 minutes after sugar rinse. The concentration of acetic acid was much higher in the extracellular fluids of dental plaque at any time. It is suggested that there may be some relationship between acetic acid and caries process.