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k-Oligocarrageenan (OC) is an effective biostimulator and a protector against disease infections for plants. However, the effect of OC molecular weight (MW) on plant growth is not fully understood. In this work, OCs with three different MWs (42, 17 and 4 kDa) was prepared by varying the degradation reaction time using ascorbic acid as a reagent. The product structure was confirmed by Fourier-transform infrared spectroscopy (FTIR) data. The growth promotion for maize (Zea mays L.) plants was investigated by foliar spray application of the prepared OCs. Field trials were carried out in two years, 2018 and 2019. The results showed that among treatments, OC with 4 kDa exhibited the best performance in both crop growth and grain yield parameters which indicated increases compared to the control in plant height (6.9–19.9%), length of ears (12.2%), diameter of ears (9.1%), fresh grain weight (17.8%), dry grain weight (20.0%) and grain yield (21.3%). Moreover, low MW OC augmented NP uptake in the plant growth while no effect on K uptake was observed. Therefore, OC with low MWs is potentially promising to apply as a promoter to enhance yield of crops.

Surface pretreatment plays important role in improvement of corrosion resistance and adhesion of organic coatings. A new generation of metal pretreatments based on nanosize zirconium oxide or ogranosilane film has been investigated recently as an alternative method to phosphatation. In this paper, ZrO2/silane composite film on carbon steel was prepared and characterised by field emission scanning electron microscopy, energy dispersive X-ray spectrum and electrochemical measurements. The effect of ZrO2/silane surface treatment on the protection properties of powder coating was studied by salt spray test and adhesion measurement. The results obtained showed that ZrO2 was rapidly precipitated on the steel surface after first 1 minute immersion and ZrO2/silane film formed after 4 minutes immersion give best protective properties. Powder coating on carbon steel with ZrO2/silane pretreatement has equivalent protection performance like powder coating with  phosphate pretreatment.

Carbon steel was treated by immersion in silane doped hexafluorozirconic acid solution. Treated surface was characterized by field emission scanning electron microscopy (FE-SEM) and electrochemical methods. The effect of ZrO2/silane pretreatment on the protective properties of powder coating was studied by adhesion measurement and electrochemical impedance spectroscopy (EIS). The obtained results showed that the morphology and electrochemical characteristics of ZrO2/silane film depend on solution pH. Surface morphology was uniform and compact at solution pH = 4. The best corrosion performance obtained with the film formed in solution with pH and immersion time of 4 and 4 mins, respectively. The ZrO2/silane pretreatment significantly improved adhesion and corrosion resistance of powder coating on carbon steel.

The fucoidanase from the digestive glands of the marine shell Vasticardium flavum was studied. The fucoidanase catalysed the hydrolysis of 1→3-L-fucan from sea cucumbers Stichopus variegatus, Holothuria spinifera, did not catalyze the hydrolysis of fucoidan from F. evanescens and F. vesiculosus containing alternating α-1→4 and α-1→3 glycoside bonds. This enzyme also did not catalyze the hydrolysis of fucoidan from U. pinnatifida, S. mcclurei, which belong to the galactofucan group. Optima of pH and time incubation were at 3-4 and 24 hours, respectively. The enzyme activity was significantly increased in the presence of the Ca2+, Ba2+, Co2+ and Mg2+ cations, but the Cu2+, Sn2+, Fe2+ and Al3+ cations partially inactivated the enzyme. The enzyme was completely inactivated after 5 min of incubation at 65° C.