Are fluid inclusions in gypsum reliable paleoenvironmental indicators? An assessment of the evidence from the Messinian evaporites

The paleosalinity of water from which the gypsum precipitated during the Messinian salinity crisis is a controversial issue. Recent microthermometry studies on primary fluid inclusions in gypsum provided very low salinity values not compatible with precipitation from seawater, and suggested strong mixing between seawater and nonmarine waters enriched in calcium sulfate. We applied a new microthermometric protocol on gypsum crystals from nine Mediterranean sections that were experimentally stretched to measure a larger population of fluid inclusions. The results show salinities ranging from 9 to 238 wt‰ NaCl equivalent, largely falling within the evaporation path of normal seawater. The data from previous studies were obtained mostly from those fluid inclusions capable of nucleating a stable bubble after a weak stretching, which probably correspond to those having a lower salinity acquired through post-depositional crack-and-seal processes. Our data suggest instead that the primary gypsum precipitated from a marine brine, later modified by post-trapping processes during tectonics and exhumation.

Effects of Calcium Sulfate Whiskers on the Mechanical Properties and Light Transmittance of PE Greenhouse Films

Calcium sulfate whisker (CSW) is a kind of fiber crystal material with high orientation structure. The major goal of this research is to study the changes of mechanical properties and light transmittance of PE greenhouse film with different proportions of CSW. The experimental results show that the mechanical properties and light transmittance of PE/CSW films are enhanced compared with the pure PE. For PE/2%CSW, it shows a 18.6% increase in tear strength, a 3.1% increase in luminous transmittance and 17.7% increase in haze. The PE/5%CSW demonstrates a 12.8% higher in tensile strength, a 20.5% higher in tear strength, a 23.9% lower in luminous transmittance and a 53.0% higher in haze. This article gives a new formula to strengthen the mechanical properties of PE greenhouse films and finds the direction for the research and development of astigmatic covering film.

GEL FORMATION IN THE KAOLIN SYSTEM - SODIUM ALGINATE - CALCIUM SULFATE - SODIUM PYROPHOSPHATE

Представлены результаты исследований изменений происходящих при формировании наполненных альгинатных гелей при внутреннем диффузионном гелеобразовании. Исследование проводилось для систем, состоящих из каолина и альгината натрия с системой отверждения из сульфата кальция и пирофосфата натрия. Установлено, что применение реологических методов исследования позволяют получать данные о показателях качества альгинатных гелей и их составе, и механизме гелеобразования. Установлено, что для системы каолин – альгинат натрия – сульфат кальция – пирофосфат натрия при формировании альгинатного геля целесообразно использовать сульфат кальция с массовой долей от 5 до 6,5, а пирофосфат натрия с массовой долей от 1,5 до 3 % при гидромодуле 1 к 3 и температуре воды 20 °С.Эти данные можно использовать при разработке рецептуры альгинатных масок и подготовки нормативной технической документации. The results of studies of changes occurring during the formation of filled alginate gels during internal diffusion gelation are presented. The study was carried out for systems consisting of kaolin and sodium alginate with a curing system of calcium sulfate and sodium pyrophosphate. It has been established that the use of rheological research methods makes it possible to obtain data on the quality indicators of alginate gels and their composition, and the mechanism of gelation. It was found that for the system kaolin-sodium alginate-calcium sulfate-sodium pyrophosphate when forming an alginate gel, it is advisable to use calcium sulfate with a mass fraction of 5 to 6.5, and sodium pyrophosphate with a mass fraction of 1.5 to 3% at a hydromodule 1 to 3 and a water temperature of 20 °C. This data can be used in the development of the formulation of alginate masks and the preparation of regulatory technical documentation.

Multi-stage controllable degradation of strontium-doped calcium sulfate hemihydrate-Tricalcium phosphate microsphere composite as a substitute for osteoporotic bone defect repairing: Degradation behavior and bone response

Various requirements for the repair of complex bone defects have motivated to development of scaffolds with adjustable degradation rates and biological functions. Tricalcium phosphate and calcium sulfate are the most commonly used bone repair materials in the clinic, how to better combine tricalcium phosphate and calcium sulfate and play their greatest advantages in the repair of osteoporotic bone defect is the focus of our research. In this study, a series of scaffolds with multistage-controlled degradation properties composed of strontium-doped calcium sulfate (SrCSH) and strontium-doped tricalcium phosphate microspheres (Sr-TCP) scaffolds were prepared, and their osteogenic activity, in vivo degradation and bone regeneration ability in tibia of osteoporotic rats were evaluated. In vitro studies revealed that different components of SrCSH/Sr-TCP scaffolds significantly promoted the proliferation and differentiation of MC3T3-E1 cells, which showed a good osteogenic induction activity. In vivo degradation results showed that the degradation time of composite scaffolds could be controlled in a large range (6-12 months) by controlling the porosity and phase composition of Sr-TCP microspheres. The results of osteoporotic femoral defect repair showed that when the degradation rate of scaffold matched with the growth rate of new bone, the parameters such as BMD, BV/TV, Tb.Th, angiogenesis marker CD31 and new bone formation marker OCN expression were higher, which promoted the rapid repair of osteoporotic bone defects. On the contrary, the slow degradation rate of scaffolds hindered the growth of new bone to a certain extent. This study elucidates the importance of the degradation rate of scaffolds for the repair of osteoporotic bone defects, and the design considerations can be extended to other bone repair materials, which is expected to provide new ideas for the development of tissue engineering materials in the future.

Simple superphosphate by two-stage acid treatment of phosphate raw materials

The distinguishing feature of the proposed flow method before the classical (chamber) method is that the entire production cycle of natural phosphate processing is carried out in two stages. At the first stage, the phosphorite is treated with a stoichiometric flow rate of concentrated sulphuric acid (at least 93%), under conditions of complete decomposition of phosphorite to form phosphoric acid and crystals of anhydrite (calcium sulfate). The reaction temperature is 122 °C. In the second stage, the resulting concentrated solution of phosphoric acid in a mixture with sulphur is involved in a reaction with an additional input of phosphorite, which is the basis for the mechanism of chemical formation of monocalciumphosphate and granulation of superphosphate mass. The processes for neutralizing phosphoric acid on monocalciumphosphate and for granulating the product by coagulation are combined in one apparatus. The drying stage of the product is excluded from the scheme.