The hydration of two different polymorphs microcrystalline cellulose (cellulose I and II), as well the amorphous was studied using water sorption calorimetry, gravimetric vapor sorption, nitrogen X-ray powder diffraction. Amorphous prepared by means ball-milling (MCC). Whereas data showed untreated MCC to consist I, found recrystallize into II after contact with or at relative humidities (RHs) above 90%. Sorption isotherms show an increase in sequence < cellulose. enthalpy becomes more...

Hydration plays a fundamental role in maintaining the three-dimensional structure and function of proteins. In this study, Raman spectroscopy was used to probe hydration induced structural changes at various sites lysozyme under isothermal conditions range water contents from 0 44 wt %. curves were constructed detailed analysis marker bands. Transition inflection points (w(m)) onsets determined have shown that start 7-10 end about 35 % water. The onset coincides with broad glass transition...

Hydration of mesoporous silica MCM-41 was studied using the method sorption calorimetry. By combining water and nitrogen experiments, we calculated density silanol groups on surface as 1.6 nm-2. Comparison capillary condensation regimes showed that apparent confined in pores is ca. 0.88 g/cm3. The pore diameter a combination X-ray data 39 Å. Calculations based application Kelvin−Cohan equation are reasonable agreement with this value. calorimetric results show driven by enthalpy; entropic...

Mesoporous silica has received much attention due to its well-defined structural order, high surface area, and tunable pore diameter. To successfully employ mesoporous for nanotechnology applications it is important consider how influenced by solvent molecules the fact that most preparation procedures involve treatment in various solvents. In present work we contribute this topic with new results on MCM-41 affected a simple alcohol at room temperature. The effects of are characterized TGA,...

The stability of biologically produced pharmaceuticals is the limiting factor to various applications, which can be improved by formulation in solid-state forms, mostly via lyophilization. Knowledge about protein structure at molecular level solid state and its transition upon rehydration however scarce, yet it most likely affects physical chemical biological drug. In this work, synchrotron small- wide-angle X-ray scattering (SWAXS) are used characterize a model protein, lysozyme, structural...

We report a detailed density functional theory and molecular dynamics study of hydrogen bonding between trehalose water, with special emphasis on interactions in the amorphous solid state. For comparison, water-water water dimers tetramers are evaluated using quantum calculations. The results show that energy is dependent not only geometry (bond length angle) but also local environment bond. This seen calculations complexes vacuum as well states periodic boundary conditions....

Disordered materials in the glassy state show different gas sorption properties compared to same liquid or rubbery state. The enthalpy becomes more exothermic, and absorbed amount is greater data are often treated literature using dual-mode theory—a three-parameter model. This work presents another approach where a isotherm model for derived from thermodynamic consideration of glass transition properties. particularly applicable describing that obey Henry's law limit parameters correspond...

A two-site magnetic exchange model comprising a set of two linear first-order differential Bloch-McConnell equations is considered. The relaxation and behavior described using symmetrical form the general solution derived in case longitudinal magnetization for zero initial conditions. inverse problem with limited information has been solved exactly an analytical explicit under mild priori knowledge about parameters.

One of the essential functions mucous gel is protection tissues against dehydration. The effect hydration on structural and thermodynamic properties pig gastric mucin (PGM) bovine submaxillary gland (BSM) have been studied using atomic force microscopy (AFM), sorption, differential scanning calorimetry (DSC). analysis sorption isotherms shows higher water capacity PGM compared to BSM at RH levels lower than about 78%. value enthalpy zero content 25 °C for both biopolymers -20 kJ/mol. Glass...

The freeze-drying of proteins, along with excipients, offers a solution for increasing the shelf-life protein pharmaceuticals. Using differential scanning calorimetry, thermogravimetric analysis, sorption and synchrotron small-angle X-ray scattering (SAXS), we have characterized properties at low (re)hydration levels lysozyme, which was freeze-dried together excipient sucrose. We observe that residual moisture content in these samples increases addition lysozyme. This results from an...

Sedimentation is an important property of colloidal systems that should be considered when designing pharmaceutical formulations. In applications, sedimentation normally described using Stokes' law, which assumes laminar flow fluid. this work we studied swelling and hydration spherical cross-linked amorphous starch microspheres in pure water, solutions sodium chloride, pH-adjusted aqueous solutions. We demonstrated Reynolds numbers obtained these experiments correspond to the transition...

Characterization and tuning of the porosity amorphous starch materials are important for many applications, including controlled release encapsulated proteins. The porosities these in dry hydrated states can have different physicochemical origins properties. Here, cross-linked microspheres their hydration-induced transformations were characterized by small angle X-ray scattering, scanning electron optical microscopies, thermogravimetric analysis, sorption calorimetry, nitrogen sorption,...

The ice crystallization and melting in systems where the equilibrium state is difficult to reach one of growing areas pharmaceutical freeze-drying research. quality final freeze-dried product depends on parameters cooling step, which affect nucleation growth. In this paper, we present a DSC study sucrose-water system. Using two different types thermal cycles, examine influence heating rates behavior solutions with water contents between 50 100 wt%.The results show that low provide at higher...

In this work, we describe the application of a sorption calorimeter to study binary system n-octyl β-d-glucoside/water at 25, 40, and 60 °C. At 25 °C also carried out experiments with heavy water which showed similar results those normal water. The method used allows one simultaneously obtain information about activity enthalpy mixing in systems. obtained show that hydration is endothermic hence driven by entropy. We have specified concentration ranges thermodynamic properties different...

A differential scanning calorimetric and sorption study of two alkyl maltosides, C8G2 C10G2, was performed. In the dry state, C10G2 do not form solid crystals but undergo a glass transition upon temperature change. The is partly ordered has same lamellar structure as liquid formed by maltosides. To reflect presence structure, terms "glassy crystals" can be used. mechanism relaxation glassy based on results small-angle X-ray scattering experiments proposed. Experiments water showed that turn...

Hydration of hen egg white lysozyme was studied by using the method sorption calorimetry at 25, 40, and 50 °C. Desorption calorimetric measurements were performed 25 40 The activity water partial molar enthalpy mixing determined as functions content. occurs in four steps: slow penetration into protein−protein interface; gradual glass transition, which every protein molecule independently other molecules; further uptake with disaggregation aggregates formation a monolayer water; accumulation...

Synopsis Objectives The mammalian skin is a barrier that effectively separates the water‐rich interior of body from normally dryer exterior. Changes in external conditions, for example ambient humidity, have been shown to affect properties. prime objective this study was evaluate effect water activity topical formulation on hydration and permeability. A second gain more understanding how two commonly used humectants, urea glycerol, function vivo . Methods Simple aqueous formulations were...