Hydroxymethyl Cellulose Research Articles

Preparation and Characterization of Nanoscale Semiconductor Particles of ZnS, CdS, and PbCrO4 in Polymer–Surfactant Gel Matrix

The preparation of fairly monodisperse nanoparticles of zinc sulfide, cadmium sulfide, and lead chromate using a polymer–surfactant gel matrix as the template to resist particle clustering is been described. A hydrophobically modified polymer (chloride salt of N,N′‐dimethyl‐N‐methyl derivative of hydroxymethyl cellulose, JR 400) and a surfactant (sodium dodecyl sulfate, SDS) have been used to form the gel matrix. The nanodispersions formed in the gel at different precursor concentrations have been characterized by the TEM and SEM. Their UV‐visible and fluorescence spectra have been measured and analyzed. The band gaps and other characteristic properties of the nanomaterials have been estimated from the spectral data. A procedure for isolation of the products from the gel is described.

Caracterisation par analyse thermique de la lignine, de la cellulose et de quelques uns de ses derives etherifies

Cellulose and its derivatives (methyl cellulose, sodium carboxymethyl cellulose, hydroxymethyl cellulose and hydroxypropyl cellulose) used as excipients in pharmaceutical industry can be characterised by simultaneous thermoanalytical (DTA and TG) methods, based on the temperatures of exothermic peaks. Lignine cellulose can be identified by taking into account the difference in temperature between the first exothermic DTA peak and the corresponding DTG peak.

'Laterally aggregated' polyacrylamide gels for electrophoresis.

A new method is described for producing highly porous polyacrylamide matrices: polymerization in presence of a preformed hydrophilic polymer. If a standard mixture of monomers (e.g., 5%T, 4%C) is polymerized in presence of, e.g., polyethylene glycol (PEG) 10 kDa, lateral chain aggregation occurs, with formation of large pore sizes. In PEG 10 kDa, the transition from a small- to a large-pore gel is clearly apparent at 0.5% PEG addition and reaches a plateau already at 2.5% PEG. Even with shorter PEG fragments (6.2 and 1 kDa) this transition occurs, but with progressively larger amounts of PEG in solution (up to 25% for the 1 kDa species). Other polymers such as hydroxymethyl cellulose (1000 kDa) and polyvinyl-pyrrolidone (360 kDa and 25 kDa) are also able to elicit this phenomenon. It appears that lateral chain aggregation (before the cross-linking event) is induced via intra-chain hydrogen bonding, since urea and temperature strongly inhibit it, whereas tetramethylurea (an agent quenching hydrophobic interactions) does not hamper it. By scanning electron microscope, it is found that the maximum pore size obtained in a 5%T, 4%C gel in presence of 2.5% PEG 10 kDA is of the order of 0.5 micron, whereas the same 5%T, 4%C control gel would have an average pore diameter of 5 nm. Thus, an increment of pore size of about 2 orders of magnitude is obtained: in these new matrices, a 21000 bp DNA fragment exhibits a much greater migration than in a control gel in which the sample is entrapped at the application site.

Adjuvants Prolonging the Residual Activity of Dichlorvos and Mevinphos in the Laboratory12

Seventy-four materials were screened as potential adjuvants to prolong toxicity of dichlorvos and mevinphos on 3rd-instar larvae of the Mexican bean beetle, Epilachna varivestis Mulsant, and 4th-instar larvae of the southern armyworm, Prodenia eridania (Cramer). Residues of the toxicants and toxicant-adjuvant combinations on lima bean foliage (‘Fordhook 242’), when 24 hours old, were infested with insects. After 24 additional hours the respomes to the combinations were compared with responses to the toxicant alone. Most adjuvants tested appeared to have some promise. Four materials, Keltose (alginate). Dacagin (polysaccharide gum), Plaskon 9405 (polyester resin), and Hetron HLR 254 (unsaturated polyester resin), were exceptionally effective. Patterns of effectiveness were observed also among individuals and categories of adjuvants. Klucel G (cellulose ether) and Methoccl MC 8000 (hydroxymethyl cellulose) were effective only in combination with mevinphos. Cellosize QP 52,000 (hydroxyethyl cellulose) and Hetron PR 130 (polyester resin) were only effective with dichlorvos. Klucel I (cellulose ether) was effective with both toxicants but only against Mexican bean beetle. On a numerical basis the carbohydrate, polyester resin, and polyvinyl derivatives categories were superior to the other categories. Approximately 90% of the above-mentioned materials produced minimum mortalities of 85%, even though they contain only about 50% of the materials tested.