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The major causes of vase life reduction in cut flowers are the microbial proliferation in vase solution and consequently vascular occlusion preventing water uptakes. In order to control microbial proliferation efficiently, silver nanoparticles (Ag-NPs) are used as an enhancer to assess leaf extracts of Psidium guajava and Andrographis paniculata to alleviate xylem blockage in cut Mokara Red orchid flowers. The basal stem of each flower was re-cut and then pulsed with 0, 5 and 10 mg/L Ag-NPs for 24 h. The floral preservative solutions are comprised of control (125 mg/L 8-hydroxyquinoline citrate, 8-HQC) and double combination leaf extracts (DCLE) of P. guajava and A. paniculata, each at 15 mg/L. The preservative solutions of DCLE with 5 mg/L Ag-NPs had higher rates of solution uptake and trace amounts of bacterial suspension, which were responsible for increasing the vase life of cut Mokara Red Orchid flowers for 15.49 ± 0.15 days, compared to the 8-HQC control treatment 8.73 ± 0.16 days. Therefore, leaf extracts of P. guajava and A. paniculata have the potential as a biocide to minimize microbial populations and prolong the vase life of cut flowers. However, the potential activities of specific antimicrobial compounds to extend the vase life need to be tested.

A new series of calamitic liquid crystal materials with bisazobenzene moieties as a core has been synthesised and characterised by spectroscopic methods. The mesomorphic properties were investigated by differential scanning calorimetry, optical polarising microscopy and X-ray diffraction. The presence of nematic and smectic A mesophases was confirmed by the textures and X-ray diffraction studies. All the compounds are found to show enantiotropic mesophase behaviour. The compounds show a significant photoisomerisation under appropriate light irradiation.

Polystyrene grafted with acrylonitrile using gamma-irradiation technique was successfully synthesized. This process was carried out at various gamma dose (0.2-1.5 Mrad). The new grafted polymer was characterized and its properties were investigated. The results indicate that best grafting percentage ratio could be revealed when the concentration of the catalyst Ferrous Ammonium Sulphate (FAS) is about 2% and the monomer concentration is 90%, at 1.25 Mrad dose. The new grafted polymer was proved by FTIR, TGA and Viscosity techniques, which was analyzed and studied with a suggested presented mechanism. The adding of acrylonitrile to polystyrene improved the physical properties of polystyrene

New series of calamitic liquid crystal materials with rod-shape azobenzene moieties as a core has been synthesized and characterized by spectroscopic methods. The mesomorphic properties were investigated by differential scanning colorimetry, polarizing optical microscopy and X-ray diffraction. The rod-shaped molecule 1-methoxyalkyloxy-4`-(4-phenylazo)acetophenone was prepared by diazotization of 4-Aminoacetophenone, coupling with phenol and subsequent etherification of 1-bromoalkyloxy-4`-(4-phenylazo)acetophenone in methanol. The presence of smectic A mesophases was confirmed by the textures and X-ray diffraction studies. Compounds 4a-4d (C3-C6) exhibits enantiotropic smectic A phase while, compound 4d (C8) show monotropic smectic A phase.

In this article, the graft copolymerization of methyl methacrylate (MMA) onto sago starch (AGU) was carried out in aqueous medium using potassium persulfate (PPS) under nitrogen gas atmosphere. The maximum percentage of grafting achieved was 90% under optimized conditions of reaction temperature, monomer, PPS, AGU, and reaction period corresponding to 50°C, 47 mmol, 1.82 mmol, 6.17 × 10−3 mol L−1, and 1.5 h, respectively. The grafting of MMA onto sago starch was confirmed by the differences in infrared spectroscopy. The viscosity measurement and the average molecular weight determination were estimated using Huggin's and Mark Houwink's equations, respectively. This material may have application as a biodegradable plastic. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 94: 1891–1897, 2004

Syntheses of novel liquid-crystalline polymers containing azobenzene moieties were performed by a convenient route with an acrylate backbone. The azobenzenes were key intermediates of the monomers, and side-chain liquid-crystalline polymers were prepared, that is, poly[α-{4-[(4-acetylphenyl)azo]phenoxy}alkyloxy]acrylates, for which the spacer length was 3 or 11 methylene units. In addition, poly[3-{4-[(3,5-dimethylphenyl)azo]phenoxy}propyloxy]acrylate was prepared with a spacer length of 3 methylene units. The structures of the precursors, monomers, and polymers were characterized with Fourier transform infrared, 1H-NMR, and 13C-NMR techniques. The polymers were obtained by conventional free-radical polymerization with 2,2′-azobisisobutyronitrile as an initiator. The phase-transition temperatures of the polymers were studied with differential scanning calorimetry, and the phase structures were evaluated with a polarizing optical microscopy technique. The results showed that two of the monomers and their corresponding polymers exhibited nematic liquid-crystalline behavior, and one of the monomers and its corresponding polymer showed smectic liquid-crystalline behavior. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 86: 2653–2661, 2002

The present research was conducted to discover antimicrobial compounds in methanolic leaf extracts ofJatropha curcasandAndrographis paniculataand ethanolic leaf extract ofPsidium guajavaand the effectiveness against microbes on flower preservative solution of cut Mokara Red orchid flowers was evaluated. The leaves were analyzed using gas chromatography-mass spectrometry. A total of nine, 66, and 29 compounds were identified inJ. curcas,P. guajava, andA. paniculataleaf extracts, with five (88.18%), four (34.66%), and three (50.47%) having unique antimicrobial compounds, respectively. The experimental design on vase life was conducted using a completely randomized design with 10 replications. The flower vase life was about 6 days in the solution containing theP. guajavaandA. paniculataleaf extracts at 15mg/L. Moreover, solution with leaf extracts ofA. paniculatahad the lowest bacterial count compared toP. guajavaandJ. curcas. Thus, these leaf extracts revealed the presence of relevant antimicrobial compounds. The leaf extracts have the potential as a cut flower solution to minimize microbial populations and extend flower vase life. However, the activities of specific antimicrobial compounds and double or triple combination leaf extracts to enhance the effectiveness to extend the vase life need to be tested.

Poly(methyl acrylate) (PMA) grafted sago starch was prepared from the reaction between methyl acrylate and sago starch by free radical initiating process in which ceric ammonium nitrate (CAN) was used as an initiator. The common procedure was used to prepare a new polymer containing hydroxamic acid functional group from PMA grafted sago starch and hydroxylamine under alkaline solution. The PMA grafted sago starch and poly(hydroxamic acid) was characterized by FT-IR spectroscopy. The water absorbency or swelling of the poly (hydroxamic acid) absorbent was measured as a function of different sago starch concentration in absorbent. It was observed that the swelling in distilled water and various salt solutions increases with decreasing sago starch concentration. The maximum absorbency in water was 192 g water g−1 at 31% sago starch content in absorbent. The absorbency in the various salt solutions decreases with the increasing salt concentration in solution. At the same salt concentration in solution, the swelling has the following tendency: Na+>Ca2+>Fe3+.

The preparation of a chelating ion-exchange resin containing amidoxime functional group was carried out by polyacrylonitrile (PAN) grafted sago starch. The PAN grafted copolymer was obtained by free-radical initiating process using ceric ammonium nitrate as an initiator. Conversion of nitrile groups of the grafted copolymer into the amidoxime was carried out by treatment with hydroxylamine under alkaline solution. The chelating poly(amidoxime) resin was characterized by FT-IR spectra, TG and DSC analyses. The chelating behavior of the prepared resin was carried out by using some metal ions. A significant binding property of metal ions by the chelating resin was observed and the maximum copper capacity was 3.0 mmol g ˇ1 at pH 6. The sorption capacities of metal ions by the resin were pHdependent, and its selectivity towards these metal ions is in the following order: Cu 2a >F e 3a >A s 3a >Z n 2a > Ni 2a >C d 2a >C o 2a >C r 3a >P b 2a . The rate of exchange was rapid, i.e. t1=2 < 9 min, based on the exchange of copper

Nanocomposites of organo Zn‐Al layered double hydroxide (LDH) with natural rubber (SMR CV60) were successfully synthesized and characterized. To prepare the nanocomposites, a hydrophilic Zn‐Al layer double hydroxide (ZnAl LDH ‐NO3−) was first converted into the organophilic form by using dodecylsulphate ion (DS) as a guest in Zn‐Al layer double hydroxide (ZnAl LDH‐DS). Intercalation of dodecylsulphate anion into the interlayer of LDH increased the surface area and the porosity of LDH. Nanocomposites of NR / ZnAl LDH‐DS was then prepared by melt intercalation method using Haake internal mixer. The resulting compounds were then vulcanizated using the conventional method. X‐Ray diffractogram the organophilic ZnAl‐DS LDH shows the basal spacing of the ZnAl‐LDH expands from 0.89 nm with nitrate as the intergallery anions to 2.53 nm due to the accommodation of DS surfactant anions. After the compounding with the natural rubber, the basal spacing of ZnAl LDH‐DS in the composites is increased to 3.90 and 3.66 nm when the Zn‐Al‐LDH‐DS contents are 1 phr and 15 phr respectively. TEM revealed the layered double hydroxide generally uniformly distributed in the rubber matrix. Further characterization indicates that the tensile strength of NR/ Zn‐Al LDH‐DS (nanocomposites) is higher than that of the NR/Zn‐Al LDH‐NO3− (macrocomposites).

Metathesis reaction of natural rubber was carried out using tungusten hexachloride and tetramethyl tin in chlorobenzene. The rubber had to be purified by several times precipitations before the reaction. Molecular weight decreased very much with the progress of reaction and with the increase of temperature. However, NMR studies indicated considerable decreases of carbon-carbon double bonds, which can not be explained by simple metathesis reaction. Some other reactions which consumed unsaturation have to be taken into account to elucidate the exact structure of resultant oligomers.

The radiation-response characteristics of polymetharylic acid gel dosimeter prepared with different concentrations of monomer and cross-linker is described in these studies. The dosimeters were prepared under the hypoxic condition in a glove box and were then irradiated with gamma-rays produced by Co-60 radionuclide that was generated at 1.25MeV energy. The irradiation took place at different doses ranged from 0Gy to 19Gy. Due to the radiation activities, chain-reaction polymerisation processes had taken place in the formation of polymethacrylic acid (PMAA) gel, which cause the dose response mechanism increased in the NMR relaxation rates of protons. It has been observed that for higher concentration of monomer and cross-linker, the polymerization rate was increased.

The open photoacoustic cell technique is used to measure the thermal diffusivity value of conducting polyaniline doped with different sulphonic acids. It is based on the measuring of the photoacoustic signal as a,function of modulation frequency. In the present work the measured thermal diffusivity and electrical conductivity values were (4.55-6.02)/spl times/10/sup -2/ cm/sup 2//s. and of (4.48/spl times/10/sup -3/-3.22) S cm/sup -1/ respectively. The IR absorbance spectra are also reported.

A new series of calamitic liquid crystalline non-symmetric dimer containing bisazobenzene moiety and a rather short alkoxybiphenyl linked by flexible spacers (4-propyloxy-[4-biphenyloxyalkyl]-4′-(4-phenylazo)azobenzene has been designed, synthesized and characterized by spectroscopic methods. The transition temperatures and phase behaviors were studied by differential scanning calorimetry (DSC), polarizing optical microscopy (POM) and X-ray diffraction (XRD) analyses. All the synthesized compounds exhibited enantiotropic phase with dimers containing propyl, butyl and octyl flexible alkyl spacers showing SmA and those with pentyl and hexyl spacers exhibited SmA and SmC phases respectively and the stability of the smectic layer depends on the spacer length for the compounds studied.