| Gypsum is a sulphate mineral anhydrite gypsum,commonly used for clinical.Clinical commonly used raw gypsum and calcined gypsum.Raw gypsum has the properties of sweet,pungent,and great cold.Gypsum has the effect of heat-clearing and fire-purging,relieving restlessness and quench.It can cure exogenous high fever and polydipsia,etc.Calcined gypsum has the properties of sweet,pungent,astringent,and cold.Calcined gypsum has the effect of hygroscopic,generating muscle,closing sores and hemostasis.It may treat ulceration and traumatic bleeding for external.It can be seen obviously that the properties of gypsum have been allayed,and the efficacy and clinical application have been changed.The results show that the calcination temperature is a key factor affecting the quality of calcined gypsum,and has a direct effect on the pharmacological effects of calcined products.Therefore,it is important to clarify the correlation between the temperature and the quality and curative effect of the calcined gypsum,and improve the quality control method of the processed product.It is great significance to ensure the clinical efficacy of gypsum.In this study,commonly mineral analysis methods are applied to gypsum,such as thermal analysis,electron microscope,spectrum analysis,processing of X-ray diffraction techniques,etc,to strictly control the processing conditions,and clear the effect of calcining temperature on the physicochemical properties,antipyretic and antibacterial of gypsum,such as crystal water removal,weight loss,the main phase,chemical composition,crystal structure,trace elements,calcium ion solubility,etc.Comprehensive analysis of the quality-structure-activity relationship,to clarify the best calcined gypsum conditionsObjectiveStudy on the effects of different calcining conditions on physicochemical properties of the calcined gypsum,analyzed the variation of the indexes in the process of calcined gypsum,combined with pharmacological experiments,explore the processing principle and effect of calcining gypsum changes,provide the basis for the optimization of gypsum calcining process.Methods1.Effect of origin factors on gypsumIn order to investigate the influence of geographical factors on gypsum,the gypsums from different origins of Hubei,Shandong,Shanxi,Anhui,Hebei and Henan were selected for infrared spectroscopy,X-ray diffraction and thermal analysis,respectively.And from the chemical structure,phase composition,pyrolysis characteristics perspective to explore the origin influences on gypsum.2.Effect of calcining temperature on the physical and chemical properties of gypsumHubei samples were taken as the object of study,according to the results of thermal analysis and fumigation,110,140,170,200,250,300,350,400,450 and 750? were used to select 10 temperature points.After the temperature was calcined,the microstructure was simulated by scanning electron microscopy,infrared spectroscopy,X-ray diffraction and chemical titration were used to study on the changes of physical and chemical properties before and after gypsum processed,and the influence of calcination temperature on the physical and chemical properties of gypsum was analyzed.3.Effects of processing on the pharmacological action of gypsumThe pharmacological model was selected according to the function of raw and calcined gypsum's clinical application.The effects of calcined products on the bacteriostasis of Staphylococcus aureus and Escherichia coli were investigated by in vitro antibacterial experiments.Result1.Effect of origin factors on gypsumThe characteristic peaks of 12 common peaks were determined by infrared spectroscopy.The considerable characteristic bands above 3545.59?3406.35?3237.38?2920.56?2850.47?2241.84?1687.54?1621.05?1115.42?668.44?601.31?462.95 cm-1.The similarity of the samples is similar.The similarity between the samples is more than 0.9955.The similarity of Hubei and Hebei is the highest,and the similarity is 0.9998.X-ray diffraction(XRD)analysis revealed 13 peaks with common peaks as gypsum.The similarity of XRD patterns of different origin gypsums is different,and the peak number and peak intensity of each spectrum are different,with none impurity peaks appear.Which is the famous land of Hubei gypsum and other origin of the biggest difference,with a unique characteristic peaks,indicating that Hubei gypsum fiber is stronger.The results show that the thermogravimetric curves and differential thermal curves of gypsum in different areas are basically the same.Gypsum samples from the temperature rise to 80? began to lose weight,heated to 200? when the basic weight loss has been completely.Heated to 350?,DTA curve exothermic reaction peak,indicating that the gypsum crystal structure has changed.DTG curve results show that gypsum in the heating process,the first loss of 3/2 of crystal water,and finally lost the remaining 1/2 crystal water.2.Effect of calcining temperature on the physical and chemical properties of gypsumThe results show that gypsum begins to lose weight from 80?,indicating that gypsum begins to lose crystal water at this temperature,but the process of dehydration is slow.After that,the higher the calcination temperature,the faster the gypsum loss rate and the loss of crystal water The shorter the time.Under the experimental conditions,the calcined temperature is 140?250?,the gypsum in 10min to complete the water loss process,but the crystal structure has not changed.At 300?350? fuming conditions,DTA curve began to exothermic reaction peak,indicating that the gypsum at this time not only quickly lose crystal water,crystal form has also changed.Continue to increase the temperature,gypsum weight loss law is basically no longer change.Scanning electron microscopy,infrared and XRD studies have shown that the thermal transition temperature of gypsum is from 300 to 350?,from hemihydrate gypsum to soluble anhydrite.In this temperature conditions calcined gypsum,calcined product structure is the most loose,continue to heat the crystal structure but become dense.At this time the plaster completely dehydrated,trace element content is higher,powder and decoction of calcium ions in the more.3.Effects of processing on the pharmacological action of gypsumThe high,medium and low dose groups of gypsum had a certain antipyretic effect on yeast rats.Compared with the model group,there was significant difference between the two groups.The calcined gypsum had no antipyretic effect.Calcined gypsum has a certain bacteriostatic effect on golden yellow grapevine,Escherichia coli and Shigella bacteria,and the best results are obtained at 300,350?.ConclusionThe composition and structure of gypsum in different areas are similar,and the influence of origin factors on gypsum is small.Hubei gypsum has a certain representative.Scanning electron microscopy,infrared and XRD studies have shown that the thermal transition temperature of gypsum is from 300 to 350?,from hemihydrate gypsum to soluble anhydrite.At this point the plaster completely dehydrated,trace element content and calcium ion dissolution more,in line with the provisions of the Pharmacopoeia,antipyretic effect disappeared,resulting in a certain antibacterial effect.Comprehensive analysis,that 300?350?for the calcined gypsum is appropriate temperature. |
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