Melting of Krypton Layers Adsorbed in Cylindrical Pores

The mechanism of melting and its correlation to adsorption on cylindrical surfaces of silica-like cylindrical nanopores has been studied for the first time. The size of the pores has been defined by its diameter (4 nm in this work). As an example, we have analyzed krypton atoms as adsorbed system. We have shown, that the layer adsorbed on the surface of the pore has much lower melting temperature (T = 77.5 K) than both the filled pore (T = 90 K) and the bulk system (T = 118 K). The mechanism of melting in the layer is a continuous transition and depends on the vacancy formation. The layering transition changes its character with temperature from a sharp transition below the melting temperature into a continuous one above it.     

Thickness of Adsorbed Polystyrene Layers by Ellipsometry,

The adsorption of polystyrene from cyclohexane below the theta temperature onto chrome ferrotype plate was studied by means of ellipsometry (polarization spectrometry). In this technique changes in the state of polarization of polarized light are measured upon reflection from a film-covered surface. The measurements were carried out in situ and permitted determination of the thickness and refractive index of the swollen polymer film at the solidsolution interface. A concentration range of 0.18 to 9.7 mg/ml was studied for polymer with a molecular weight of 76,000. The thickness of the adsorbed film increased with increasing solution concentration, reaching a plateau for most of the concentration range studied. The average thickness at this plateau was approximately 210 Å. The adsorbed film was highly swollen, consisting of about 12 g/100 ml of polymer for most of the concentration range. The amount adsorbed was determined to be approximately 2.25×10⁻⁴ mg/cm² at the plateau. Comparison of the radius of gyration of polystyrene in solvent is made to the results obtained.     

Interactions in Caseinate/Gelatin Systems

Abstract

Interactions in mixtures of gelatin and sodium casemate have been studied over a range of pH. Phase separation in these mixtures has been examined using electrophoresis to identify protein components involved in complex formation. Rheological properties and functional properties of compatible mixtures have been evaluated. Mixtures of 1 % acid-processed gelatin and 1 % caseinatc were found to interact at pH 5.5 to form a separate complex coacervale phase. At lower pH levels, the caseinate component formed aggregates but did not precipitate in the presence of gelatin. These complex systems had increased gel strength compared with gelatin alone and produced low-melting gels of reduced elasticity. Further synergistic increases in gel strength were observed in the presence of 10% maltodextrin..     

Some Interactions Between Gelatin and Surfactants

Abstract

The interactions between gelatin and sodium dodecyl sulphate (SDS) were studied with respect to the viscosity increase. Beside the temperature, pHand SDS concentration, we learned that the starting viscosity is of importance. Obviously, the high molecular parts have a major influence. These interactions can be suppressed by a suitable modification.     

Improvements of Some Physical Properties in Gelatin Layers

The effect of copolymer formation in situ in the photographic layer by the reaction between the gelatin, a cyclodextrin derivative and a diepoxy crosslinking agent was investigated. The melting point increase, the swelling ability and the optical rotatory dispersion were determined. The photographic characteristics were investigated in silver bromide layers containing gelatin-cyclodextrin copolymer.

It has been found that the copolymer makes rapid diffusion of the developing agent possible at a low water absorption and high degree of hardening of the layer. This feature can be explained by the decrease of the hydration of polypeptide chains by copolymer formation and the favourable. spatial structure of the copolymer molecules.     

Convective Diffusion Of Water In Swelling Gelatin Layers

The literature concerning the swell of gelatin layers immersed in water is reviewed. It is shown that all of the published swell equations are effectively special cases of a general empirical rate equation. In an attempt to establish mechanism, a hypothetical scheme is proposed involving a concentration-dependent intrinsic diffusion coefficient, a linear adsorption isotherm relating the free and sorbed water concentrations, a constant ratio of final swell to dry thickness, and a proportionality between the local swell and the sorbed water con-centration. It is shown for this hypothetical scheme that the convective one-dimensional diffusion equation can be linearized and solved exactly for the appropriate boundan/ and initial conditions. It is also shown that the general solution takes a particularly simple form for moderately long times after immersion. Experimental sivell data are then used to deduce values for the intrinsic diffusion coefficient which compare favourably with the self-diffusion coefficient of water. It is also shown that an exact solution to the associated problem of desorption of water from the fully swollen layer can be obtained by a simple rearrangement of the boundary and initial conditions.     

The Penetration Rate of Photographic Chemicals into Gelatin Layers and into Emulsion Layers under Development

The infiltration rate of water through dry gelatin layers and the penetration rate of developing agents, OH^-, HCHO and other organic and inorganic developer ingredients through gelatin layers, gel or emulsion layers were determined by five methods.

The penetration of OH^- through gelatin layers depends considerably on pH, ionic strength and total alkalinity and, in spite of its high mobility in water, it penetrates slower than developing agents at the pH and ionic strength of normal developers due to consumption by gelatin.

Under diffusion-controlled development of emulsion layers, the distance of penetration of developing agents was roughly proportional to the square root of the penetration time, but the apparent rate was 1 or 2 orders of magnitude slower than that for a simple gelatin layer, depending on Agx/gelatin ratio and degree of hardening of the layer.

The results from direct comparison of penetration of developing agents and OH^- in the same emulsion layer under diffusion-controlled development showed that, higher swelling, lower hardener content and higher Agx concentration proved more favorable to the reduction controlled by penetration of developing agent, rather than by that of OH^-.

The experiments also show that, in rapid processing by developer of high pH and high ionic strength, the rate of water infiltration becomes important for the rate of development, in its early stages.     

Convective Diffusion of Water in Gelatin Layers: Application of Theory to Process Optimization

Abstract

A review of the analytical theory of the convective diffusion of water in a swelling gelatin layer is presented, together with an outline of the effect of varying hardness on times of imbibition and drying. Development time is calculated using the Danckwerts' method and the appropriate diffusion coefficient, assuming that developer begins to diffuse into the layer when it is fully swollen and that a constant mass of silver is produced without significant halide loss. The total processing time is then considered as a function of layer hardness.     

Sound Speed and Density Studies of Interactions Between Cationic Surfactants and Aqueous Gelatin Solution

Studies on the interactions of surfactants with proteins can contribute to an understanding of the action of surfactants as denaturants and as solubilizing agents for membranes of proteins and lipids. Quantitative aspects of such studies may include direct measurements of properties, such as viscosity, density, sound speed, conductance, and elucidation of the often highly complex phase diagrams. In this study, sound speed and density studies of surfactants, viz., cetyltrimethyl ammonium bromide, cetyltrimethyl ammonium chloride, and di(dodecydimethyl ammonium bromide) (12-2-12) have been carried out in a 0.02 % w/v aqueous solution of gelatin at temperatures of 20 °C, 25 °C, 30 °C, and 35 °C. From the measured data, the parameters apparent molar volumes ((f_v){(phi_{v})}), adiabatic compressibility (β), and apparent molar compressibility (f_k){(phi_{k})} have been calculated to interpret the protein–surfactant interactions. The variations in these parameters with the concentration of the surfactant suggests the manifestation of hydrophobic interactions in the system.     

Thermal Transitions in Gelatin and Aqueous Gelatin Solutions

On the basis of the characteristic enthalpy changes associated with glass transformation, the glass transition (T_g) in gelatin can be detected readily, in addition to the helix-to-coiltransition, by difTerential scanning calorimetry, and the effects of water content on these transitions can be measured directly. The thermal behaviour of aqueous, deionized bone-gelatin systems with up to about 20 wt";' water is typical of amorphous or partially amorphous polymer-diluent systems depending upon the amount of gelatin structural order developed. Extrapolations of the T_g data to the T_g reported for water and of the helix-to-coiltransition data to that reported for aqueous gelatin solutions containing 90 wt% water are reasonable. Further, the T_g data suggest that the equilibrium water contents of aqueous gelatin systems containing gelatin structural order are higher than those of structureless systems at corresponding relative humidities.     

Interactions between Ti and alumina-based ceramics

Reactive metal coatings have been frequently used on ceramic materials for various purposes. However, little work was done in the past to understand the interactions between coating and ceramic substrates and their effects on the mechanical properties of the ceramics. In this study, titanium coatings were applied to single-crystal (sapphire) and polycrystalline alumina to study the interface reactions. Also, the effect of the coating on the mechanical properties of the substrates was quantified in terms of modulus of rupture (MOR) in four-point bending strength. Reactions between the coating and the Al₂O₃-based substrates at 980°C caused the formation of a new phase, Ti₃Al[O], and a significant decrease (15%–65%) in the MOR strength of the ceramic materials. This study showed that in polycrystalline alumina, interactions between titanium and the glassy grain-boundary phase in the ceramic materials were responsible for reduction in the MOR strength, while the effect of thermal expansion mismatch between titanium and the ceramic substrate appeared to be dominant for singlecrystal alumina.     

Interactions between human neutrophils and mucin-coated surfaces

Recently, we showed microscopically that bovine (BSM), porcine (PGM) and human (MG1) mucin coatings could suppress the adhesion of neutrophils to a polyethylene terephthalate-based model biomaterial (Thermanox). Here, using the release of reactive oxygen species (ROS) as a marker of material-induced neutrophil activation, the strong surface-passivating effects of these mucin coatings were corroborated. Under optimal adsorption conditions, all mucin species performed equally well, thus indicating a high degree of functional homology between the mucins. Cell adhesion and morphology correlated well with the release of ROS. Quartz crystal microbalance (QCM-D) analysis linked low neutrophil activation to efficient mucin surface-shielding. Interestingly, the shielding power appeared equal for thick expanded and thin compact mucin coatings. Combined mucin-serum coatings were found to be highly surface-passivating. Particularly, since our data suggested partly synergistic mucin-serum action, we highlight the possibility that pre-adsorbed mucins could provide favorable support for adsorbing host components.     

Modeling Interactions between Liposomes and Hydrophobic Nanosheets

2D nanomaterials could cause structural disruption and cytotoxic effects to cells, which greatly challenges their promising biomedical applications including biosensing, bioimaging, and drug delivery. Here, the physical and mechanical interaction between lipid liposomes and hydrophobic nanosheets is studied utilizing coarse‐grained (CG) molecular dynamics (MD) simulations. The simulations reveal a variety of characteristic interaction morphologies that depend on the size and the orientation of nanosheets. Dynamic and thermodynamic analyses on the morphologic evolution provide insights into molecular motions such as “nanosheet rotation,” “lipid extraction,” “lipid flip‐flop,” and “lipid spreading.” Driven by these molecular motions, hydrophobic nanosheets cause morphologic changes of liposomes. The lipid bilayer structure can be corrugated, and the overall liposome sphere can be split or collapsed by large nanosheets. In addition, nanosheets embedded into lipid bilayers greatly weaken the fluidity of lipids, and this effect can be cumulatively enhanced as nanosheets continuously intrude. These results could facilitate molecular‐level understanding on the cytotoxicity of nanomaterials, and help future nanotoxicology studies associating computational modeling with experiments.     

Lipoglycoprotein of Gelatin

Abstract

Solvent extracts were compared with the parent gelatins by means of TLC and HPLC. The photographic effects of the various protein fractions are discussed.     

Acid Ossein Gelatin

Abstract

The properties and manufacture of acid ossein gelatin are discussed with particular reference to the use of acid ossein gelatin in the photographic and allied industries.

The effect that the demineralizing process has on the properties of the gelatin extracted has been investigated with different demineralizing media. Loss of amide ammonia during the commercial demineralizing of bone has been confirmed and the rate of this toss has been studied using calcium and ammonia analyses. Different types of acid or lime processed gelatins can be distinguished also by analysis of their titration curves. From both experimental and calculated titration curve data, some correlations are found xvith gelatin amide content and isoelectric point.

A literature review is given, highlighting some of the applications found for acid ossein gelatin in the photographic industry.     

Pt插层对NiFe/FeMn薄膜交换耦合的影响

采用磁控溅射方法制备了以Pt为缓冲层和保护层的NiFe/FeMn薄膜.在NiFe/FeMn界面插入Pt,发现交换偏置场(Hex)随着插层Pt厚度(tPt)的增加而减小.一个重要的现象是当Pt插层厚度为0.4nm时,在Het-tPt衰减曲线并非单纯指数下降,而是出现一个"凸起".通过对样品磁矩随Pt插层厚度的变化规律进行分析,发现随Pt插层厚度的增加,样品的磁矩先逐渐增大,然后又有所下降,并且稳定在某一值;表明在样品制备过程中,NiFe与FeMn之间的相互作用(如界面反应),使得在NiFe/FeMn界面存在磁死层,Pt的插入抑制了NiFe/FeMn界面磁死层的产生,有利于交换耦合;另一方面,Pt的插入隔离了NiFe和FeMn的直接接触,使得FeMn对NiFe的钉扎作用减弱,不利于交换耦合.两个方面的共同作用,使得当Pt插层为某一合适厚度时,Hex-tPt曲线出现"凸起".     

Calorimetric Study of the Desorption and Phases of 3He And 4He Adsorbed on Two Layers of H2-plated Graphite Above 0.2K

We have conducted new heat capacity studies of films of ³ He and ⁴ He adsorbed on 2.15 layers of hydrogen plating exfoliated graphite for temperatures T > 0.2K and coverages (n) over the entire first layer and beginning of the second layer. Low-density ³ He films show two-dimensional Fermi fluid behavior with no liquid-vapor condensation below 0.9K. We have mapped the n-T melting tine and estimated monolayer completion density using heat capacity isotherms. By fitting ³ He films' desorption specific heats to a theoretical model, we have calculated the ³ He binding energy (21.3K to 21. 7K) and compare it to a previous measurement for ⁴ He films on the same substrate (25.1K to 25.5K).