Evaluation of Hardening Using the Sol Fraction of Gelatin Films (Review)

The low molecular weight component of gelatin has been investigated by determination of the molecular weight distribution of the sol fraction from hardened gelatin films. The hardeners used were formaldehyde and mucochloric acid. Different hardening conditions and gelatin types were studied. It was observed that a couple of weeks were needed to reach a stable level of hardening. Acid- processed gelatins exhibited higher reactivity than lime-processed gelatins. The results indicate that the method seems to be effective as an evaluation of gelatin hardening.     

The Influence of Pre-treatment on the Properties of Photographic Gelatin

Abstract

The influence of the liming period in the manufacturing process on the chemical and photographic properties of gelatin was investigated. Three limed osseins soaked for various periods were prepared and gelatins zvere extracted from them. The impurity contents of the gelatins and the physical restraining properties decreased with prolonging liming periods. The impurity contents and physical retardance were also relative to the extraction order. The deionization treatment of gelatin decreased the impurity contents and the differences of restraining effect with extraction order. Furthermore, the fractionation of sample gelatins by use of gel permeation chromatography was applied to study the relationship to the molecular weight of impurity contents and amino acid composition, as affected by the liming period.     

Study on the Gelling Behaviour of Low Concentration Gelatin Solutions in the Cooling Process

Abstract

The authors have already reported the examination of the gelling characteristics of gelatin solution by a thermal sensor method. At solution concentrations below 4%, the gelling process was studied by optical rotatory power measurement. In this paper, the cltanges of the molecular iveight distribution (MWD) in the gelling process during the cooling period were investigated. The MWD of the gelatin solution was measured at the gelling temperature by gel permeation chromatography. The concentration of the gelatin solution was more related to the gelling phenomena than the cooling temperature. Some differences were observed in the changes of MWD among the types of gelatins.     

Ionic Strength Effects in Aqueous Solutions of Gelatin and Sodium Dodecylsulphate

Abstract

The interaction between the anionic surfactant sodium dodecylsulphate and the polyampholyte gelatin in aqueous solution has been studied by viscosity and fluorescence. Three different gelatin molecular iveights, a polydisperse gelatin and two fractionated samples derived from it, have been examined at two ionic strengths. On addition of sodium dodecylsulphate SDS, the viscosity of a low molecular weight fractionated (o.) gelatin increases smoothly with SDS concentration, unlike the polydisperse (standard) and high molecular zveight (HMW) fractionated gelatins which show maxima. The viscosity increase at the maximum increases with gelatin molecular weight. On addition of 0.1 M salt, the viscosities of the gelatin-surfactant mixtures are lower than the equivalent no-salt cases. Fluorescence studies suggest that the SDS micelles adsorbed onto these various gelatins under two different ionic strengths are remarkably similar.     

On the Rates of Gelation and the Setting Points of Gelatin Solutions

Setting temperature and setting time were obtained readily with good reproducibility. Setting speed was defined from these two values.

The relationship between the concentration (C), the cooling temperature <T) and the setting time (t) of the gelatin solution was studied using one IAG- gelatin (M-8929). The relation of these three factors could be expressed empirically as:

Int=a+b(C/T)

from which can be found the characteristic point of the gelation. It seems that this value is related to the factors controlling the gelation.

We could not find the characteristic point of the gelation for gelatin containing little high molecular weight components, resulting from ultrasonic wave irradiation.     

Evaluation of the influences of solution path length and additives concentrations on the solar photo-Fenton degradation of 4-chlorophenol using multivariate analysis

This study reports the photodegradation of 4-chlorophenol (4-CP) in aqueous solution by the photo-Fenton process using solar irradiation. The influence of solution path length, and Fe(NO(3))(3) and H(2)O(2) concentrations on the degradation of 4-CP is evaluated by response surface methodology. The degradation process was monitored by the removal of total organic carbon (TOC) and the release of chloride ion. The results showed a very important role of iron concentration either for TOC removal or dechlorination. On the other hand, a negative effect of increasing solution path length on mineralization was observed, which can be compensated by increasing the iron concentration. This permits an adjustment of the iron concentration according to the irradiation exposure area and path length (depth of a tank reactor). Under optimum conditions of 1.5 mM Fe(NO(3))(3), 20.0 mM H(2)O(2) and 4.5 cm solution path length, 17 min irradiation under solar light were sufficient to reduce a 72 mg CL(-1) solution of 4-CP by 91%.     

Physical Retardance by Modified Gelatin

Abstract

The effect of the isoionic point of gelatin on physical ripening properties was studied by the physical retardance test using modified gelatins. Carboxylic groups were blocked by the amidation reaction and amino groups were blocked by the acylation reaction.

Physical ripening speed decreased in relation to the ratio of blocked carboxylic groups and increased when the ratio of carboxylic groups increased due to acyl substitution. However we found that the final particle size of silver halide did not depend on the isoionic point of the gelatin. It was assumed that the charge shift in the gelatin molecules affected the physical ripening speed and did not affect the final particle size.     

Effect of gelatin properties in complex coacervation processes

The effects of Bloom grade and iso-electric-point of gelatin on the complex coacervation with acacia and micro-encapsulation of theobromine were investigated. The zetapotential of various gelatins and acacia was measured at different pH values and compared with the optimal pH range for complex coacervation. Values for electrical equivalence pH of gelatins and acacia were in the same range as the maximal coacervate volumes. For the high Bloom grade gelatins the pH range in which most complex coacervate was formed was smaller for Alkaline-processed gelatin than for Acid-processed gelatins. The same small pH range was observed for the low Bloom grade gelatin of the Acid-type compared to high Bloom grade gelatins of the same type. The total amount of complex coacervate increased and the relative contents of theobromine in microcapsules decreased for gelatins with high Bloom grade. Microcapsules prepared with a high Bloom grade gelatin were irregular shaped and showed poor flow characteristics. No differences in theobromine release profiles from the various microcapsules were observed     

The Role and the Effect of Calcium Ion Content of Photographic Gelatins on Coating Defects

The influence of the calcium ion content of some photographic gelatins on the adhesion of gelatin solutions to emulsion layers was investigated by surface tension, pH and viscosity measurements and by coating using the dip method.

Adhesion of the gelatin layers was examined in the coating process under the following conditions:

Surface tension at varying wetting agent concentrations, for gelatin solutions which contain calcium ions from 0 to 5760 ppm concentration.

Surface tension at varying gelatin concentrations.

Surface tension at varying pH values of the gelatin solutions used in the coating process.

The experimental results demonstrate that, at gelatin concentrations between 2 and 4%, the adhesion ability of a gelatin solution on a dry or wet gelatin (emulsion) layer depends on the Ca2* content of the coating solution. It is necessary to have at least 1000 ppm Ca2* concentration to guarantee a perfect adhesion and a perfect coating. Gelatin source, pH and the viscosity of the system are unimportant.     

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.     

Effects of N02 and S02 on the Degradation of Photographic Gelatin

Abstract

The degradation of photographic gelatin exposed to a mixture of two pollutant j gases, NO₂ and SO₂, was investigated by swelling measurements and steric I exclusion high performance liquid chromatography. The study, performed on one unhardened gelatin and two hardened gelatins, showed that all three are sensitive to pollutants. Two major effects were noted: the first was an increasing of the swelling of the gelatin films in deinineralized water and the second effect was a change in the steric exclusion chromatographic profile, corresponding to a shift to smaller molecular weights. Both these phenomena indicate that the pollutant gases induce hydrolysis of the gelatin macromolecules. Nevertheless, for the same exposure, the hardened gelatins are shoum to be less degraded than the unhardened one. Thus, even if it does not protect the photographic gelatin totally from attack by the pollutant gases, hardening slozos down its deterioration.     

Measurements of the Restrainer Content of Gelatin by a Photographic Means

An emulsion is prepared and chemically sensitized using the test gelatin and a suitable standard addition of thiosulphate sensitizer. The time and temperature of digestion are also controlled and the emulsion adjusted to optimum speed by varying the addition of a synthetic restrainer. The amount of synthetic restrainer required at optimum is an inverse measure of the restraining power of the gelatin and, if it is assumed that those gelatins which require the largest omount of added restrainer contain no natural restrainer, then by comparing the amount required by a test gelatin with this amount, the restraining power of the test gelatin is obtained in terms of the added restralner. Active gelatins had restraining powers broadly in line with their nucleic acid contents. Inert gelatins also showed considerable differences in restraining power but, as they contain negligible nucleic acid, these gelatins must contain other types of restrainer. The sensitometric properties at optimum are closely similar for most gelatins, even for some widely different gelatins, as the optimum, with each test gelatin, is reached under similar restrainer- sensitizer environment. Some gelatins differ from the majority and this is taken to indicate the presence of substances other than restrainers and sensitizers.     

Investigation on the sonocatalytic degradation of parathion in the presence of nanometer rutile titanium dioxide (TiO2) catalyst

The nanometer rutile titanium dioxide (TiO2) powder was adopted to act as the sonocatalyst after treatment of high-temperature activation and the ultrasound of low power was used as an irradiation source to induce heat-treated TiO2 powder performing sonocatalytic degradation of parathion. Although there are many factors influencing sonocatalytic degradation of parathion, the experimental results demonstrate that the optimal degradation condition of parathion can be obtained when the experimental conditions such as initial concentration of 50 mg/L parathion, addition amount of 1000 mg/L nanometer rutile TiO2, ultrasonic of 30-50 kHz frequency and 50 W output power, acidity of pH 10.0 and temperature of 20 degrees C are adopted. The degradation ratio of parathion surpassed 90% within 120 min ultrasonic irradiation in these optimal experiment conditions. The total degradation process of parathion has been monitored by UV-vis spectra and ion chromatography. At last, the parathions in aqueous solution are completely degraded and become some simple inorganic ions such as NO3(-), PO4(3-), SO4(2-), etc. In addition, the sonocatalytic activities of reused TiO2 catalysts were also studied and found to decline gradually along with the reused times. In this paper, the research on sonocatalytic degradation kinetics was also been performed and found to follow pseudo first-order reaction. All experiments indicated that the sonocatalytic method in the presence of nanometer rutile TiO2 powder was an advisable choice for the treatments of non- or low-transparent organic wastewaters in future.     

Studies on the Properties of Fractionated Gelatins

Gel permeation chromatography (CPC) and temperature solubility were used to isolate different molecular weight fractions of several photographic gelatins. The dependence of the amino acid composition of impurities and metal ion contents on molecular xveight was investigated. The lower molecular weight fraction had an unusual amino acid composition. The difference in amino acid composition was observed according to the raw material species, the methods of manufacture and those of fractionation. This lower molecular weight fraction contained more tyrosine, histidine, methionine, hydroxylysine and hydrophobic amino acids than the original gelatin, while it contained less lysine, alanine and acidic amino acids than the original gelatin. It was considered that the low molecular weight fraction contained a certain amount of telopeptide, peptide from the a2 (1) chain and non- collagenous proteins. High contents of iron and calcium ions as impurities were observed in higher and lower molecular weight fractions.     

How to Orient Collagen and Gelatin

Abstract

The arrangement of triple helical domains of gelatin molecules may have important physical consequences in photographic gelatins. We review work which indicates that lyotropic liquid crystallization is important in defining molecular orientation and packing in collagens and suggest that it would be worth looking for similar effects in gelatins under certain conditions. We present a preliminary observation which suggests that gelatin can actually behave as a liquid crystal. The possible role of lyotropic liquid crystallization in photographic manufacturing and the interaction of gelatin with other photographic components, such as silver halide, needs further investigation.     

Ultra-violet Absorption of Thermally Irradiated Gelatin

The effect of thermally irradiated gelatin at various pH's on the ultra-violet absorption at 257nm, the molecular weight and the amount of thermally coagulated material has been studied.

Decrease in pH of thermal irradiation leads to molecular weight decreases and ultra-violet absorption increases. The ultra-violet absorption correlates with the molecular weight of the thermally irradiated gelatin. At pH 3-4, however, irradiation leads to a very high ultra-violet absorption which is outside the regression line. The level of thermally coagulated material also increased in this pH range. It would seem that the ultra-violet absorption increase at pH 3-4 is related to the thermal coagulation reaction.     

The Identification of the Sugar In Gelatin

A method involving hydrolysis, resin treatment, concentration and paper chromatography is given for the identification of the sugars in gelatin. The main sugar is found to be galactose. Minor amounts of glucose may also occur but mannose and other common sugars are absent. The presence of hexosamine and hexuronic acid in gelatin is also demonstrated. There is a hint of differences between the carbohydrate of hide and bone gelatins.     

Optimized photocatalytic degradation of Alcian Blue 8 GX in the presence of TiO2 suspensions

The photocatalytic degradation of Alcian Blue 8 GX, a cationic copper phthalocyanine dye, has been investigated in aqueous suspensions containing the commercial catalyst TiO(2) P-25. The photodegradation of the organic molecule follows approximately a pseudo-first kinetic order, according to the Langmuir-Hinshelwood model. The effect of catalyst concentration, pH of the initial solution and the H(2)O(2) concentration upon the reaction rate was ascertained. It was shown that the photocatalytic degradation reaction can be mathematically described as a function of parameters such as pH, H(2)O(2) concentration and irradiation time, being modeled by the use of the response surface methodology. Optimized values for oxidizing agent, concentration, pH and UV exposure time for the studied system were determined.     

Laser induced photocatalytic degradation of hazardous dye (Safranin-O) using self synthesized nanocrystalline WO3

The photocatalytic degradation of Safranin-O (known as Basic Red 2) in water using locally synthesized nanocrystalline WO(3) as a photocatalyst was investigated under UV laser irradiation. The photo-oxidation removal of the dye was monitored by UV-vis spectrophotometer. The blank experiments for either laser irradiated only Safranin-O solution or the suspension containing WO(3) and Safranin-O in the dark showed that both laser illumination and the photocatalyst were essential for the removal of Safranin-O. The effect of experimental parameters including laser energy, catalyst loading, solution pH and the initial dye concentration on photocatalytic degradation of Basic Red 2 were also investigated. Results indicate that the rate of reaction is strongly influenced by the adsorption of an azo dye into the surface of the photocatalyst materials and suggests an optimum catalyst loading and dye concentration for the degradation reaction. It was investigated that the adsorption of the dye decreases at higher alkaline pH because both catalyst and substrate are negatively charged, developing repulsive forces between them. Kinetic data obtained reveals that the rate of the reaction obeys the first-order kinetics.     

The wear and fracture behaviour of ultra high molecular weight polyethylene subjected to γ-irradiation in an atmosphere of acetylene

The wear and mechanical properties of GUR 1020 (Perplas IMP 2000-2) Ultra High Molecular Weight Polyethylene (UHMWPE) subjected to -irradiation in an atmosphere of acetylene, were evaluated for a range of processing conditions of irradiation, annealing and ageing. The results were compared with those obtained for the virgin UHMWPE material and material processed using conventional -irradiation in nitrogen. Cross-linking produced by irradiation in acetylene, followed by subsequent annealing was found to be significantly more effective in improving the mechanical and wear properties of UHMWPE compared to when the material was irradiated in nitrogen. Gel fraction analysis on its own, while being able to detect the degree of cross-linking, was found to be insufficient in determining the effectiveness of the cross-links and the resulting mechanical properties of the UHMWPE material. The results suggest that -irradiation in an atmosphere of acetylene may provide significant advantages over conventional UHMWPE processing and irradiation cross-linking techniques.