Arie Markus

Effect of encapsulation on the persistence of Bacillus thuringiensis var. israelensis, serotype H-14

SummaryEncapsulation of Bacillus thuringiensis var. israelensis Serotype H-14 (B.t.i.) in polyethylene strongly increased its persistence against second stage Aedes aegypti larvae in laboratory conditions simulating natural field conditions. B.t.i. encapsulated in palmitic acid was less persistent. The reasons for the enhanced efficacy of encapsulated B.t.i. are discussed.

RELEASE CHARACTERISTICS OF ENCAPSULATED FORMULATIONS INCORPORATING PLANT GROWTH FACTORS

The release characteristics of encapsulated formulations containing a combination of plant growth factors (PGF)—plant hormones (IBA, paclobutrazol), nutrients (fertilizers, microelements), and fungicide (prochloraz)—were studied. The formulations were prepared by encapsulating the active ingredients in a polyethylene matrix and, in some cases, subsequently coating the product with polyurethane. Dissolution experiments were carried out with both coated and non-coated formulations to determine the sustained release patterns of the active ingredients. The PGF controlled-release systems obtained have been shown to promote development of root systems, vegetative growth, and reproductive development in cuttings, potted plants, or garden plants of various plant species. These beneficial effects are attributable to the lasting and balanced PGF availability provided by these systems.

Encapsulation of vitamin A

Vitamin A was protected from degradation in the first compartment of the ruminant stomach by encapsulation by a phase-separation technique. The matrix components consisted of substituted cellulosic materials, fatty acids or a variety of proteins. Antioxidants such as butylated hydroxytoluene and ethoxyquin were incorporated in the formulations. The protective efficiency of the formulations as estimated by exposing the encapsulated vitamin A to gastric juice (microbial degradation) and to a pepsin solution (enzymatic degradation). The capsules prepared with substituted cellulosic materials gave the best protection to vitamin A from degradation.

Promotion of rooting and development of cuttings by plant growth factors formulated into a controlled-release system

Abstract. The effect of long-acting formulations of plant growth factors (PGFs) on rooting was investigated in a mung bean cuttings model system, in five semi-hard olive cultivars and in a range of garden plants. The PGFs, which comprised the hormones indole-3-butyric acid and paclobutrazol, the nutrients N, P, and K and trace elements, and the protecting agent Sportac, improved rooting and promoted the development of the root system. The PGFs were formulated into encapsulated controlled-release systems by means of an extrusion technique, a coating method, or their combination. Chemical and biological testing of the encapsulated formulations showed a prolonged release pattern for each of the ingredients. The controlled release PGF delivery system presented in this study may serve as a platform for a wide range of horticultural uses of premixed formulations contributing to the efforts towards a safe environment.

Photosensitizedcis-trans isomerization of jojoba wax

Jojoba wax solutions were irradiated at wavelengths longer than 366 nm, in the presence of sensitizers, at room temperature.Cis-trans isomerization took place only with sensitizers with triplet energy greater than 68 kcal/mol. Quantum yields were low and a conversion of up to 25% of thetrans isomer was achieved at the photostationary state.

Synthesis of steroidal cyclopropanes

22,23-Methylenestigmast-5-en-3β-ol (IX), 24,25-methylenecholest-5-en-3β-ol (VII) and 24,25-methylene-lanost-8-en-3β-ol (XI) were synthesized by treating stigmasterol, desmosterol, and lanosterol with dichloro-carbene and reducing the adducts (VIII) and (VI) formed. Desmosteryl acetate (V) was synthesized by a novel method from 3β-acetoxychol-5-en-24-oic acid (I), the essential steps being preparation of the diazo-ketone (II), its photochemical Wolff rearrangement to the methyl ester (III), a Grignard reaction of (III) with methylmagnesium iodide and dehydration of the product.

Encapsulation of triphenyltin hydroxide

Triphenyltin hydroxide was encapsulated to prolong its fungicidal activity and to decrease its phytotoxicity in peanut fields. The envelopes found to be adequate for this purpose were polyureas and ethyl cellulose, as was demonstrated by biological tests.