Leaf pigments, ribulose-1,5-bisphosphate carboxylase, nitrate reductase and photosynthetic efficiency of grapevine (Vitis vinifera L. cv. Pinot noir) grown under different light conditions

Changes of leaf pigments, ribulose-1,5-bisphosphate carboxylase (Rubisco), nitrate reductase and photosynthetic efficiency were determined in leaves of Vitis vinifera L. cv. Pinot noir plants grown at full sunlight (2000 µmol m-2 s-1) and 40 % of sunlight (800 µmol m-2 s-1). The contents of chlorophyll and carotenoids per fresh mass were higher in 40 % sunlight than in full sunlight-grown leaves. In contrast, Rubisco activity, in vivo nitrate reductase activity (indicator of nitrate utilisation) and soluble proteins were significantly reduced in 40 % sunlight-grown leaves. In isolated thylakoids, a marked inhibition of whole chain (PSI+PSII) and PSII activity were observed in 40 % sunlight-grown leaves. Smaller inhibition of NI activity was also observed in 40 % sunlight-grown leaves. The artificial exogenous electron donors, DPC and NH2OH, significantly restored the loss of PSII activity in 40 % sunlight-grown leaves. The same results were obtained when Fv/Fm was evaluated by chlorophyll fluorescence measurements. The marked loss of PSII activity in 40 % sunlight-grown leaves was due to the loss of 47, 33, 28-25 and 23 kDa polypeptides. This conclusion was confirmed by immunological studies showing that the content of the 33 kDa protein of the water-splitting complex was diminished significantly in 40 % sunlight-grown leaves.

Photosynthetic functioning of individual grapevine leaves (Vitis vinifera L. cv. Pinot noir) during ontogeny in the field

Field studies were conducted to investigate ontogenic changes in photosynthesis of a single grapevine leaf (Vitis vinifera L. cv. Pinot noir) subtending the fruit. A 40-day-old leaf was physiologically most active with regard to net photosynthetic (Pn) and electron transport rates. Variable to maximum fluorescence ratios of dark-adapted leaves (Fv/Fm = 0.77) were higher in mature leaves than in expanding (0.66) or senescent ones (0.65). Lower Fv/Fm values in these stages seemed to be caused not by photoinhibition but by a low photochemical capacity as suggested from the chlorophyll a/b ratios. In isolated thylakoids, lower rates of whole chain and PSII activity were observed in expanding and senescent leaves, while higher rates were observed in mature leaves. A similar trend was noticed for Rubisco and total soluble proteins. The artificial exogenous electron donors Mn2+ failed to restore the loss of PSII activity in senescent leaves, while DPC and NH2OH significantly restored the loss of PSII activity. The m arked loss of PSII activity in senescent leaves was primarily due to the loss of 33, 28-25, 23 and 17 kDa polypepides. A marked loss of Rubisco activity in senescent leaves is mainly due to the loss of 15 (SSU) and 55 (LSU) kDa polypeptides

Experimental Investigation of Catalytic Surface Reaction for Different Metal Surfaces

The use of a catalytic surface to enhance chemical reaction rates is a well established and common practice. However, its use in combustion devices for enhancing combustion reaction is somewhat less common and more recent. Catalytic combustors, because of their inherent ability to operate at very lean air fuel mixtures, can maintain a relatively low combustion temperature and hence reduce the formation of NOx significantly. Further the catalytic coating on the combustion chamber walls enhances the combustion process by increased rate of pre-flame reactions. This provides a basis for catalytic combustion in lean burn engine. A considerable amount of effort has been devoted in the present work to this experimental study and compares different catalyst reaction performance.A cylindrical chamber is fabricated and air-fuel mixture is passed through the chamber. A metal tube coated with the catalyst is placed inside the control volume and it is heated by an electric heater. The air-fuel mixture undergoes pre-flame combustion reaction and as a result of this, the miniature temperature increases. Various catalytic surfaces like mild steel, Nickel, Chromium and copper were tested. The activation temperatures of these catalytic surfaces were obtained from this experimental work. Keywords: catalytic reaction, LPG, activation energy, catalytic coatin

Green synthesis of ZnO nanoparticles and their photocatalyst degradation and antibacterial activity

The current study aimed to synthesize nanoparticles of Zinc oxide (ZnO) using the extract of Acalypha indica leaves and their photocatalyst degradation and antibacterial properties were also measured. The biosynthesized nanoparticles were analyzed using XRD, UV-visible, FT-IR, and SEM with EDAX, DLS, PL, and Zeta potential analysis. The synthesized nanoparticles had a mean size of 16 nm measured by XRD which was highly pure, and their spherical shape was confirmed by SEM. The UV-visible confirmed that ZnO nanoparticles have a direct band gap energy is 3.34 eV. The measured zeta size and potential of synthesized nanoparticles were 46 nm and -27 mV, respectively, determined by the DLS technique can be considered moderately stable colloidal solutions. The FT-IR analysis confirmed the presence of functional groups in the leaf extract and the ZnO nanoparticles. The biosynthesized ZnO nanoparticles have a homogeneous spherical morphology and the average particle is 35 nm. The PL analyses performed on synthesized nanoparticles showed a sharp blue band at 362 nm, which was attributed to the defects of structure in ZnO crystals. During natural sunlight illumination, ZnO nanoparticles demonstrated notable degradation of the dye methyl blue (MB). At 90 min of illumination, the degradation efficiency achieved was 96 %. Antibacterial properties were observed for synthesized nanoparticles against four bacterial strains, including Bacillus subtilis, Staphylococcus aureus, Pseudomonas aeruginosa, and Escherichia coli. The highest zone of inhibition was observed against Escherichia coli (25.2 mm). Overall, these studies indicate that Acalypha indica is a good sell for planting, and has the greatest chance of being used to develop nanoparticles for protection against environmental pollution and human health

Effects of in-cylinder catalytic coating on the performance of a two-stroke spark ignition engine

1-7Two-stroke spark ignited engines offer superior power to weight ratio, which is best suited for two-wheeler applications. But, low thermal efficiency and higher emission levels are the main drawbacks of these engines. In-cylinder catalytic coating was applied in a two-stroke single cylinder spark ignited engine for improving thermal efficiency and reducing emission levels. The selected catalyst (copper), which is an oxidation catalyst, was coated over the inside surface of cylinder head and piston crown by plasma coating method. Detailed studies were carried out to evaluate the performance of catalyst under varied operating conditions. The copper coated engine showed improved fuel economy at all operating conditions. The brake thermal efficiency was improved by 10% and the unburned hydrocarbon emission was reduced by 25% at full load condition of the engine. The plasma coating of catalyst showed no deterioration after 50 h of operation and the catalytic action was not affected. Detailed combustion analysis was carried out to find out the effect of catalyst action on combustion parameters. It was found that the rate of burning, Pmax, and heat release rate were increased. Combustion duration was reduced by 8° of crank angle at full load condition