Reclamation of sodic soils has traditionally been undertaken using calculation of gypsum or Ca requirement assuming 100% exchange efficiency and neglect of the contribution of calcium carbonate in the profile. The UNSATCHEM model is reviewed and then evaluated for its ability to predict field reclamation of a sodic saline soil. The 40-ha field site was initially at an electrical conductivity (E...

Microbes in Haughton Crater Sulfates: Impact craters are of high interest in planetary exploration because they are viewed as possible sites for evidence of life [1]. Hydrothermal systems in craters are particularly regarded as sites where primitive life could evolve. Evidence from the Miocene Haughton impact structure shows that crater hydrothermal deposits may also be a preferred site for sub...

PURPOSE The study aimed to identify the accuracy and reproducibility of preparations made by gypsum materials of various colors using quantitative and semi-quantitative three-dimensional (3D) approach. MATERIALS AND METHODS A titanium maxillary first molar preparation was created as reference dataset (REF). Silicone impressions were duplicated from REF and randomized into 6 groups (n=8). Gyps...

Surface crystallization of calcium sulfate dihydrate (gypsum) on a series of polymeric surfaces was studied using a quartz microbalance system. Polyelectrolyte multilayer films (positively and negatively charged surfaces) were formed on the quartz crystal microbalance (QCM) sensors utilizing a layer-by-layer spin-assembly method. The kinetics of gypsum surface crystallization was quantified in ...

The ability of gypsum, a common sulfate mineral, to host arsenic atoms in its crystalline structure, is demonstrated through experimental structural studies of the solid solutions formed upon synthetic coprecipitation of gypsum (CaSO4 x 2 H2O) and arsenic. Neutron and X-ray diffraction methods show an enlargement of the gypsum unit cell proportional to the concentration of arsenic in the solids...

PURPOSE The aim of this study was to evaluate occlusal contacts generated by 3 different biogeneric design modes (individual (BI), copy (BC), reference (BR)) of CEREC software and to assess the designs subjectively. MATERIALS AND METHODS Ten pairs of maxillary and mandibular casts were obtained from full dentate individuals. Gypsum cast contacts were quantified with articulating paper and dig...

The aim of this study was to evaluate the physical properties of irreversible hydrocolloid materials poured immediately and after different storage periods. Four alginates were tested: Color Change (Cavex); Hydrogum (Zhermack); Hydrogum 5 (Zhermack); and Hydro Print Premium (Coltene). Their physical properties, including the recovery from deformation (n = 3), compressive strength (n = 3), and d...

Impact craters and associated hydrothermal systems are regarded as sites within which life could originateonEarth,andonMars.TheHaughton impactcrater,oneof themostwell preservedcratersonEarth, is abundant inCa-sulphates. Selenite, a transparent form of gypsum, has been colonized by viable cyanobacteria. Basementrocks,whichhavebeenshocked,aremoreabundant inendolithicorganisms,whencomparedwithunsh...

This study evaluated the accuracy of gypsum casts after different impression techniques and double pouring. Ten patients were selected and for each one it was obtained 5 partial putty/wash impressions with vinyl polysiloxane (VPS) material from teeth #13 to #16 with partial metal stock trays. The following techniques were performed: (1) one-step; two-step relief with: (2) PVC film; (3) slow-spe...

Gypsum has two important states (fresh and hardened states), and the addition of phase change materials (PCM) can vary the properties of the material. Many authors have extensively studied properties in the hardened state; however, the variation of fresh state properties due to the addition of Micronal® DS 5001 X PCM into gypsum has been the object of few investigations. Properties in fresh sta...