Boiler ash as catalyst for the catalytic synthesis of organic carbonates

Over the years production of crude glycerol has been in an increasing pattern due to the rapid growth of biodiesel industry. Therefore, the market value of glycerol has dropped drastically in recent years. To overcome this problem, the conversion of glycerol into fine chemical such as glycerol carbonate through an economical catalytic synthesis route using boiler ash as catalyst was carried out in this study. Besides, Malaysia is the second largest oil palm producer in the world and about 4 million tons of boiler ash is produced annually from incineration of palm fruits, palm kernels, palm shells and palm fibres which contains variety of interesting metal elements. A series of catalysts were prepared using various calcination temperatures and through catalytic testing, the boiler ash calcined at 900 oC under static air (BA 900) was identified as the most active catalyst. The highest catalytic activity obtained resulted in an average of 93.6 ± 0.4 % conversion of glycerol, 90.1 ± 1.0 % selectivity of glycerol carbonate and 84.3 ± 1.1 % yield of glycerol carbonate at optimum reaction conditions of 150 °C, 4 h, molar ratio of 1:1.5 (glycerol: urea) plus stirring rate of 340 rpm. Potassium silicate (K2SiO3) present in boiler ash subsequently promoted the selective conversion of glycerol carbamate intermediate to glycerol carbonate at an accelerated manner in which K+ acted as weak Lewis acid while the SiO3 2- as conjugated basic site. It was found that, K+ activates the carbonyl group of urea while the conjugated basic SiO3 2- activates the hydroxyl group of glycerol to form glycerol carbonate. The turnover frequency (TOF) value calculated for both BA 900 (126.5 mmol/ g.cat.h-1) and K2SiO3 (125.6 mmol/ g.cat.h-1) were comparable, thus confirming similar active sites responsible for catalytic reaction. Although, studies using direct utilisation of industrial crude glycerol revealed that the catalyst is feasible to produce glycerol carbonate, the presence of impurities at certain amount in crude glycerol affected the catalytic activity. Boiler ash is also a versatile catalyst to synthesise ethylene carbonate and propylene carbonate. It was evidently proven that boiler ash showed similar catalytic pathway in synthesis of the three different carbonates. The current study pioneers in introducing catalyst derived from waste for the production of organic carbonate. It also proposes new scheme of mechanistic pathway at an accelerated manner for the synthesis of organic carbonates while proposing direct utilisation of crude glycerol without prior purification. In concise, the studies employed is near to a complete green synthesis approach as it suggests proper utilisation of waste boiler ash as catalyst and crude glycerol as feedstock

Low Metal Loading Palladium Mixed-Oxides Catalyst for the Synthesis of Glycerol Carbonate

Glycerol carbonate can be readily synthesized from glycerol and urea catalyzed by PdZnO, PdSnO2, SnO2, and ZnO. The superior catalytic activity of ZnO over SnO2 is mainly due to basicity property. The incorporation of low metal loading of Pd on both SnO2 and ZnO produced higher yield of glycerol carbonate to bulk material counterpart. In addition, the sol-gel technique was shown to have higher turn-over frequency (TOF) due to highly disperse Pd with small crystallite size

Reusable Gypsum Based Catalyst for Synthesis of Glycerol Carbonate from Glycerol and Urea

In this study, the catalytic carbonylation of glycerol with urea in the presence of gypsum based heterogeneous catalyst is reported for the first time. Gypsum (CaSO4·2H2O) is one of the two calcium sulphate minerals found in nature and also one of the waste materials produced from advanced material industrial processing plant. The effect of physical and chemical pre-treatment procedures on gypsum was investigated. To obtain the catalyst structure-activity relationship, the treated catalysts were characterized by means of several characterization techniques (i.e. XRD, TGA, BET surface area, SEM, FTIR, CO2–TPD, NH3–TPD and Hammett test). Tuneable physico-chemical properties of gypsum based catalysts were successfully prepared by varying the pre-treatment techniques, which later on contributed to the variation of catalytic activity toward glycerol carbonate formation from glycerol. The highest catalytic activity obtained was for catalyst consisting β-CaSO4 phase where it produced 92.8% conversion of glycerol, 90.1% selectivity and 83.6% yield of glycerol carbonate, respectively. The gypsum catalyst is easily recoverable and reusable for subsequent cycles of reaction. Similar physico-chemical properties of fresh and used catalyst were confirmed through XRD, FTIR and Hammett test analysis. Besides, the mechanistic pathway of glycerol carbonate was confirmed through the formation of glycerol carbamate as intermediate compound which was further established through time online analysis study using 13C NMR and ATR–FTIR, respectively. The study also clearly supports conversion of waste into wealth while promising proper disposal of waste to produce value added product

microRNAs mature with help from cancer biology

A report of the Keystone Symposium on Molecular and Cellular Biology, 'MicroRNA and Cancer', Keystone, Colorado, USA, 10-15 June 2009

Suppression of MAPK11 or HIPK3 reduces mutant Huntingtin levels in Huntington's disease models.

Most neurodegenerative disorders are associated with accumulation of disease-relevant proteins. Among them, Huntington disease (HD) is of particular interest because of its monogenetic nature. HD is mainly caused by cytotoxicity of the defective protein encoded by the mutant Huntingtin gene (HTT). Thus, lowering mutant HTT protein (mHTT) levels would be a promising treatment strategy for HD. Here we report two kinases HIPK3 and MAPK11 as positive modulators of mHTT levels both in cells and in vivo. Both kinases regulate mHTT via their kinase activities, suggesting that inhibiting these kinases may have therapeutic values. Interestingly, their effects on HTT levels are mHTT-dependent, providing a feedback mechanism in which mHTT enhances its own level thus contributing to mHTT accumulation and disease progression. Importantly, knockout of MAPK11 significantly rescues disease-relevant behavioral phenotypes in a knockin HD mouse model. Collectively, our data reveal new therapeutic entry points for HD and target-discovery approaches for similar diseases

Regulation of microRNA biogenesis and turnover by animals and their viruses

Item does not contain fulltextMicroRNAs (miRNAs) are a ubiquitous component of gene regulatory networks that modulate the precise amounts of proteins expressed in a cell. Despite their small size, miRNA genes contain various recognition elements that enable specificity in when, where and to what extent they are expressed. The importance of precise control of miRNA expression is underscored by functional studies in model organisms and by the association between miRNA mis-expression and disease. In the last decade, identification of the pathways by which miRNAs are produced, matured and turned-over has revealed many aspects of their biogenesis that are subject to regulation. Studies in viral systems have revealed a range of mechanisms by which viruses target these pathways through viral proteins or non-coding RNAs in order to regulate cellular gene expression. In parallel, a field of study has evolved around the activation and suppression of antiviral RNA interference (RNAi) by viruses. Virus encoded suppressors of RNAi can impact miRNA biogenesis in cases where miRNA and small interfering RNA pathways converge. Here we review the literature on the mechanisms by which miRNA biogenesis and turnover are regulated in animals and the diverse strategies that viruses use to subvert or inhibit these processes

Effect of Porocentesis Upon the Blood-Aqueous Barrier of Cynomolgus Monkeys

Anterior chamber paracentesis disrupts the blood aqueous barrier (BAB) of rabbits and nonhuman primates, but the magnitude and duration of breakdown in monkeys has not been clarified. We have studied anterior chamber paracentesis in cynomolgus monkeys as a potential model of postoperative BAB breakdown. The effect of a single paracentesis upon fluorescein sodium concentration in the anterior chamber after an intravenous injection was measured in 16 eyes of 8 animals. In an additional 10 eyes of 5 animals, aqueous humor was withdrawn for analysis 24 hours and one week following paracentesis. Anterior chamber fluorescein concentration was 57 ± 22 ng/ml (mean ± standard deviation) before paracentesis, rose to 81 ± 47 ng/ml 24 hrs after paracentesis, and was 60 ± 36 ng/ml at 72-96 hours. Twenty-four hours after paracentesis, total protein concentration was elevated, but ascorbic acid and transforming growth factor-jS levels were not. Paracentesis in monkeys has only a small and short lasting effect upon BAB integrity and is therefore unlikely to be a good model for assessing the effect of agents designed to stabilize the BAB. However, the short-lived effect of paracentesis may permit the repetitive collection of "primary aqueous" for physiologic and biochemical studies. Invest Ophthalmol Vis Sci 33:165-171, 199

piRNABank: a web resource on classified and clustered Piwi-interacting RNAs

Piwi-interacting RNAs (piRNAs) are expressed in mammalian germline cells and have been identified as key players in germline development. These molecules, typically of length 25–33 nt, associate with Piwi proteins of the Argonaute family to form the Piwi-interacting RNA complex. These small regulatory RNAs have been implicated in spermatogenesis, repression of retrotransposon transposition in germline cells, epigenetic regulation and positive regulation of translation and mRNA stability. piRNABank is a highly user-friendly resource which stores empirically known sequences and other related information on piRNAs reported in human, mouse and rat. The database supports organism and chromosome-wise comprehensive search features including accession numbers, localization on chromosomes, gene name or symbol, sequence homology-based search, clusters and corresponding genes and repeat elements. It also displays each piRNA or piRNA cluster on a graphical genome-wide map (http://pirnabank.ibab.ac.in/)

Regional Drought Resilience Plan for South West Queensland 2022-2030

he South West Queensland region is often referred to as the ‘Cornerstone’ of Queensland. The region’s area is 319,808km² – almost one fifth of the area of the state – and is home to 23,777 residents (ABS 2021). This population density of 0.074 people per km², makes it one of the least populated areas in Queensland. It comprises the Local Government Areas of Maranoa Region, Murweh, Shire of Balonne, Shire of Paroo, Shire of Bulloo and Shire of Quilpie. The predominance of agriculture (and agricultural supply-chain industries) as a major source of income and employment, makes the region highly vulnerable to the impacts of unseasonal dry periods and droughts. The records for the region indicate that the South West Queensland region is one of the most likely regions in Australia to experience both prolonged droughts and flash droughts in the eastern portion of the region