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The volatile profile of the edible vegetable Gynura bicolor [Gynura bicolor (Roxb. ex Willd.) DC] was analyzed using gas chromatography-mass spectrometry (GC-MS). Isocaryophyllene (23.2%), α-pinene (16.8%), α-humulene (9.1%), β-pinene (7.3%), and copaene (7.0%) were identified as the major compounds in the leaves. In the stems, α-pinene (27.1%), β-pinene (13.0%), isocaryophyllene (7.8%), β-myrceneb (7.8%), 1-undecene (5.7%), and copaene (5.3%) were the main components. G. bicolor grows best at 25 °C. When cultivated at different temperatures (20 to 35 °C in incements of 5 °C), the volatile profiles shifted. The proportion of isocaryophyllene was lower at 20 °C than at the other temperatures. The relative amounts of α-pinene and α-humulene were highest at 20 °C, whereas copaene was highest at 35 °C. Principal component analysis (PCA) was used to explore the correlation between volatile compounds identified from the vegetative tissues and temperature treatments. It reveals the same trend with the previous statements and the first principal component (PC1) and the second principal component (PC2) explains up to 90% of the variance. Experimental results revealed that both temperature and vegetative organ correlate with the volatile emission profile of G. bicolor.

Fourier-transformed infrared spectroscopy has been employed to study the adsorption, thermal reactions and photodegradation of glycolic acid (HOCH 2 COOH) on TiO 2 in a gas–solid system. The intriguing research focus is the reactivity and evolution of the two functional groups. Glycolic acid can exist on TiO 2 at 35 °C in two dissociative adsorption forms, OCH 2 COOH and HOCH 2 COO, which are derived from hydrogen loss of the COH and COOH groups, respectively. Heating the surface to a temperature higher than ∼100 °C causes a largely enhanced carbonyl stretching band at ∼1750 cm −1 , indicative of oxidation of the OCH 2 groups of the surface glycolic acid molecules. This chemical process is supported by the adsorption of glyoxylic acid (HCOCOOH) on TiO 2 . As the surface temperature is further increased to 200 °C or higher, formate (HCOO) and methoxy (CH 3 O) are produced. Their formation is proposed via dioxymethylene (OCH 2 O) intermediate. CO and CO 2 are found to be the final thermal products. Photoirradiation of a TiO 2 surface covered with glycolic acid at ∼325 nm leads to its decomposition, generating CO 2 , CH 3 O, HCOO and carbonate species. O 2 is found to promote the photochemical reactions of glycolic acid on TiO 2 to form CO 2 , HCOO and carbonates. O 2 may play a role hampering recombination of photogenerated electron–hole pairs and participating in the formation of CO 2 and HCOO.

Fourier transform infrared spectroscopy has been employed to investigate the adsorption, thermal reactions, and photodegradation of glyoxylic acid on TiO2 in a gas−solid system. Glyoxylic acid may ...

Adsorption, thermal decomposition, and photoreactions of ethylene oxide (EO) on powdered TiO 2 have been studied by Fourier-transformed infrared spectroscopy. Most of the adsorbed EO molecules at the saturated coverage on 35 °C TiO 2 remain intact. As the temperature is increased (≥100 °C), the surface EO molecules dissociate into ethylene glycol-like species (-OCH 2 CH 2 OH or -OCH 2 CH 2 O-) by ring rupture and crotonaldehyde (CH 3 CH=CHCHO) possibly via acetaldehyde from EO isomerization. The ring-opening process is enhanced in the presence of coadsorbed H 2 O molecules. EO with the highly strained three-membered ring is thermally more reactive than 1,4-dioxane on TiO 2 . EO molecules adsorbed on TiO 2 readily undergo photodegradation in O 2 , forming surface H 2 O, CO 2 , HCO 3 , CO 3 , and HCOO. The comparative studies of 16 O 2 and 18 O 2 indicate that both O 2 and lattice oxygen take part in the EO photodecomposition. The reaction pathways involving the two oxygen species are discussed.

Anisotropically grown TiO2-B with a textural porosity and a high specific surface area has been prepared, characterized, and used to catalyze the thermal and photochemical decomposition of CH3I. The fibrous TiO2-B is fabricated by the reaction of mesoporous anatase TiO2 at 90 °C, followed by addition of 0.1 M HCl solution into the reaction precipitate to reach pH 1. Addition of 0.1 M HCl solution for other pH values of 6, 9, and 12 is also carried out to investigate the pH effect on the elemental composition and morphology of the reaction products, which provides some mechanistic clues for the formation of the TiO2-B nanofibers. XRD patterns, Raman and reflectance UV–Vis spectra, and SEM and TEM images are used to characterize the material. The TiO2-B fibers, ∼10 nm in width and several hundred nanometers in length, grow along the [ 1 2 0 1 ] direction of the monoclinic structure, as suggested by the observation of the (2 0 1) fringes which are normal to the axial direction and have a neighboring distance of 0.37 nm in the TEM images. The TiO2-B nanofibers aggregate into cotton-like particles with a size similar to that of the original anatase particles, forming mesopores with an average diameter of 4.5 nm and a high BET area as much as ∼600 m2/g which is much larger than those reported previously for titanates and TiO2-B with morphologies of tube or fiber. The TiO2-B material has an experimentally-determined bandgap energy of 3.3 eV. Its thermal and photochemical reactivities toward CH3I decomposition are demonstrated by infrared spectroscopic investigation in a gas–solid system.

Adsorption and reactions of 2-iodoethanol on TiO(2) have been studied by Fourier transform infrared spectroscopy. ICH(2)CH(2)OH possesses two reactive centers of C-I and C-OH. It is found that its decomposition leads to the formation of crotonaldehyde on TiO(2). A reaction sequence of ICH(2)CH(2)OH --ICH(2)CH(2)O- --CH(3)CHO --CH(3)CH=CH-CHO is proposed. Although the decomposition routes of C(2)H(5)OH and C(2)H(5)I, both forming C(2)H(5)O- on TiO(2), suggest that -OCH(2)CH(2)O- may play a role in the crotonaldehyde formation, reaction of HOCH(2)CH(2)OH on TiO(2) shows that this is not the case. Adsorbed H(2)O is formed in the ICH(2)CH(2)OH decomposition on TiO(2); however, it is found that ICH=CH(2), possibly generated by ICH(2)CH(2)OH dehydration, is not important in the crotonaldehyde formation.

Rice (Oryza sativa L.) seminal roots are the primary roots to emerge from germinated seeds. Here, we demonstrate that the photomorphology of the seminal roots was diverse among rice varieties, and the light-induced wavy roots were found mostly in indica-type rice varieties. The light-induced wavy morphology in rice seminal roots has been different with curling or coiling roots in some other specific conditions, such as high air humidity or high nitrogen nutrient. The efficiency of light-induced root waving was developmental stage dependent. The wavy root phenotype was caused by asymmetric cell growth around the stele. Using the inhibitors to block auxin polar transport and fatty acid oxygenation, the role of auxin and oxylipins in the morphogenesis of light-induced wavy roots was investigated. Expressions of genes encoded in the enzymes involved in fatty acid oxygenation in light-exposed roots were monitored by reverse transcriptase-polymerase chain reaction. Our results suggested that auxin polar transport was essential for inducing wavy seminal roots by light stimulus. In addition, the ketol oxylipins derived from allene oxide synthase (EC 4.2.1.92)-mediated fatty acid oxygenation function as intracellular signals for triggering the light-induced wavy root phenotype.