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The fumigant has been approved by the World Health Organization for use in grain storage, targeting the eradication of pests in areas where grain is stored or transported to reduce insect and mold activities, thereby minimizing storage losses. Phosphine is featured by its economic viability, application readibility, rapid diffusion, and lack of residue, making it advantageous for comprehensive pest control. It demonstrates high efficacy against various harmful organisms in storage, making it one of major fumigants worldwide. However, the elimination of some fumigants has increased dependence on phosphine. The lack of standardized guidance and inappropriate use of phosphine have led to severe resistance among stored grain pests, posing a threat to the effectiveness and sustainability of phosphine treatment. This paper provides a comprehensive review of the current status and trends of phosphine resistance in stored grain pests on the global. It analyzes the genetic basis of resistance, focusing on respiratory and cuticle-related gene expression and detoxification enzyme mechanisms. A comparison of four resistance detection methods--FAO, discriminating does bioassay, rapid knockdown, and molecular identification--is rendered. The study explores key strategies for resistance management, including optimization of fumigation protocols, laboratory and field validations, and application recommendations. The aim is to offer reference information for the scientific and rational use of phosphine and the development of alternative pest control methods in the future. [ABSTRACT FROM AUTHOR]

A series of side-chain liquid crystal (LC) polysiloxanes were synthesised with Poly(methylhydrogeno)siloxane, 4ʹ-(undec-10-enoyloxy) biphenyl – 4 – yl 4- (trifluoromethyl) benzoate (Mth) and a chiral nematic (N*) LC monomer 1-allyl 10-(cholesteryl)-decanedioate (Mch). The chemical structures and LC properties of the monomers and polymers were characterised by FTIR,1H-NMR, differential scanning calorimetry, thermogravimetric analysis, POM and X-ray diffractometer. Mchis monotropic N* LC. The homopolymer derived from monomer Mchis enantiotropic N* LC. Monomer Mthis a smectic A liquid crystal. The copolymers derived from Mchand Mthare N* LCs. The temperatures at which 5% weight loss occurred are greater than 300°C for all the fluoro-containing polymers, and the residue weights of the samples at 600°C increased slightly as the content of trifluoromethyl mesogens increased in the polymers. The glass transition temperatures of the polymers increased as trifluoromethyl mesogens increased, too. The N*–I phase transition temperatures show a negative deviate from ideal or linear behaviour. The values of the enthalpy changes for the cholesteryl containing polymers are rather low and this is attributed to the biaxiality of cholesteryl moiety which tends to reduce the change in the orientational order at the N*–I transition. Compared to the monomers, the polymers show wider mesophase region. [ABSTRACT FROM PUBLISHER]

A series of ortho-substituted ortho-cresol novolac resins were synthesized and used as curing agents for epoxy resins. The chemical structures of different ortho-substituted ortho-cresol novolac resins were investigated by many measurements, such as FT-IR, 1H NMR, and 13C NMR. The results indicated that the ortho-cresol novolac resin with the needed proportion of ortho-substitution was synthesized through the adjustment of the reaction conditions. The studies on the curing kinetics of ortho-cresol novolac epoxy resin cured by different ortho-cresol novolac resins showed that the activation energy was reduced with an increase in the proportion of ortho-ortho methylene bridges. [ABSTRACT FROM AUTHOR]

Reactive rubber is the most used material to improve toughness of epoxy resins. Allylated o-cresol novolac resin with certain allylation degree was prepared and characterized, then was used to cure o-cresol novolac epoxy resin and 4,4'-Bismaleimide to prepare a heat-resistant epoxy resin. So, CTBN was introduced to improve its toughness. The effect of CTBN on thermal stability and morphology were studied. With the increase of CTBN, the storage modulus of BACC resins was increased basically indicating that CTBN was homogeneously dispersed in the matrix, and there were two glass transition temperatures of BACC resins indicating that the poor compatible between BACC and CTBN than between epoxy resin and CTBN. From the morphology of BACC resins, the effect of CTBN was similar to the other terminally reactive rubber. When the content was small, there was homogenous distribution of smaller CTBN particles in cured BACC matrix, and then the phase inversion occurred with the increase of CTBN. So, in order to improve toughness of cured BACC resin, a homogenous distribution of smaller CTBN particles is necessary. These conclusions revealed that the properties of BACC resins can be tailored and it must be useful to direct design of materials. [ABSTRACT FROM AUTHOR]