Variation of Chemical Compounds of Sandalwood Oil From Various Provenances in Indonesia

The quality of sandalwood (Santalum album Linn) oil primarily depends on the compound of two major sesquiterpenes (α-santalol and β-santalol). The aim of this research was to identify variation of chemical compounds of sandalwood oil from various provenances. Fifty four samples from 8 provenances and one land race taken from 13th years old sandalwood planted at Gunungkidul, Yogyakarta Indonesia. Sandalwood powder were obtained by drilling tree at 10 cm above the ground horizontally. The samples were extracted with n-hexane solvent. Identification of chemical compounds of this essential oils were conducted by gas chromatography mass spectrometry analysis (GCMS). The GCMS investigation of sandalwood oils showed that variation compounds both among individual within provenance and between provenances were found in 11 individual from 6 provenances. Compounds such as sesquiterpene, monoterpenes, and others, were found in variying amount. The results showed that α-santalol (32.38-78.29%), β-santalol (5.45%-37.83%) were the major compounds with varying quantities of compounds range of epi-β-santalol (5.97-17.16%), P-Menth-2-En-9-OL-Trans (2.87%-8.53%), and α-sinensal (3.83-9.39%)

Extraction and Chemical Compounds Identification of Red Rice Bran Oil Using Gas Chromatography – Mass Spectrometry (GC-MS) Method

The objectives of the study are to obtain optimum yield of extraction red rice bran oil, to determine the physico-chemical characteristics, and componen coumpounds. Data was analyzed using Nir Parametric Statistics by Friedmann test. The result showed the optimum extraction results was obtained by the ratio of substrate : solvent of 1: 8 and the oil yield was 12.31 ±0.325%. The physico properties of red rice bran oil were greenish brown colour, with a density ranged from 0.908 ± 0.014 to 0.922 ± 0.014 (g/mL), and the water content ranged from 0.87 ± 0.06 to 0.91 ± 0.02 %. The chemical properties of red rice bran oil were: the acid number ranged from 116.41 ± 1.22 to 118.11 ± 2.45 (mg NaOH/g); the saponification number ranged from 193.74 ±21.88 to 199.62 ± 12.63 (mg KOH/g); and the peroxide number ranged from 24.37 ± 2.44 to 26.07 ± 4.88 (mgek/kg), respectively. Oils was analyzed used GC-MS. The chemical components of rice bran oil are oleic acid (46.24%), palmitic acid (18.25%), linoleic acid (13.29%), 9-octadecane(7.76%)

Chemical regeneration of emitter surface increases thermionic diode life

Chemical regeneration of sublimated emitter electrode increases the operating efficiency and life of thermionic diodes. A gas which forms chemical compounds with the sublimated emitter material is introduced into the space between the emitter and the collector. The compounds migrate to the emitter where they decompose and redeposit the emitter material

Self-assembly in polyoxometalate and metal coordination-based systems: synthetic approaches and developments

Utilizing new experimental approaches and gradual understanding of the underlying chemical processes has led to advances in the self-assembly of inorganic and metal–organic compounds at a very fast pace over the last decades. Exploitation of unveiled information originating from initial experimental observations has sparked the development of new families of compounds with unique structural characteristics and functionalities. The main source of inspiration for numerous research groups originated from the implementation of the design element along with the discovery of new chemical components which can self-assemble into complex structures with wide range of sizes, topologies and functionalities. Not only do self-assembled inorganic and metal–organic chemical systems belong to families of compounds with configurable structures, but also have a vast array of physical properties which reflect the chemical information stored in the various “modular” molecular subunits. The purpose of this short review article is not the exhaustive discussion of the broad field of inorganic and metal–organic chemical systems, but the discussion of some representative examples from each category which demonstrate the implementation of new synthetic approaches and design principles

Refractory-metal compound impregnation of polytetrafluoroethylene

Process impregnates polytetrafluoroethylene /PTFE/ with rhenium or molybdenum compounds. The refractory metals impregnated PTFE combines chemical inertness with electrical conductivity. They are useful for electro-chemical cells, chemical processing equipment, catalysts, electrostatic charge removal, RF gasketing, and cable shielding

Controlled exploration of chemical space by machine learning of coarse-grained representations

The size of chemical compound space is too large to be probed exhaustively. This leads high-throughput protocols to drastically subsample and results in sparse and non-uniform datasets. Rather than arbitrarily selecting compounds, we systematically explore chemical space according to the target property of interest. We first perform importance sampling by introducing a Markov chain Monte Carlo scheme across compounds. We then train an ML model on the sampled data to expand the region of chemical space probed. Our boosting procedure enhances the number of compounds by a factor 2 to 10, enabled by the ML model's coarse-grained representation, which both simplifies the structure-property relationship and reduces the size of chemical space. The ML model correctly recovers linear relationships between transfer free energies. These linear relationships correspond to features that are global to the dataset, marking the region of chemical space up to which predictions are reliable---a more robust alternative to the predictive variance. Bridging coarse-grained simulations with ML gives rise to an unprecedented database of drug-membrane insertion free energies for 1.3 million compounds.Comment: 9 pages, 5 figure

Generic Strategies for Chemical Space Exploration

Computational approaches to exploring "chemical universes", i.e., very large sets, potentially infinite sets of compounds that can be constructed by a prescribed collection of reaction mechanisms, in practice suffer from a combinatorial explosion. It quickly becomes impossible to test, for all pairs of compounds in a rapidly growing network, whether they can react with each other. More sophisticated and efficient strategies are therefore required to construct very large chemical reaction networks. Undirected labeled graphs and graph rewriting are natural models of chemical compounds and chemical reactions. Borrowing the idea of partial evaluation from functional programming, we introduce partial applications of rewrite rules. Binding substrate to rules increases the number of rules but drastically prunes the substrate sets to which it might match, resulting in dramatically reduced resource requirements. At the same time, exploration strategies can be guided, e.g. based on restrictions on the product molecules to avoid the explicit enumeration of very unlikely compounds. To this end we introduce here a generic framework for the specification of exploration strategies in graph-rewriting systems. Using key examples of complex chemical networks from sugar chemistry and the realm of metabolic networks we demonstrate the feasibility of a high-level strategy framework. The ideas presented here can not only be used for a strategy-based chemical space exploration that has close correspondence of experimental results, but are much more general. In particular, the framework can be used to emulate higher-level transformation models such as illustrated in a small puzzle game

Molecular Docking and NMR Binding Studies to Identify Novel Inhibitors of Human Phosphomevalonate Kinase

Phosphomevalonate kinase (PMK) phosphorylates mevalonate-5-phosphate (M5P) in the mevalonate pathway, which is the sole source of isoprenoids and steroids in humans. We have identified new PMK inhibitors with virtual screening, using autodock. Promising hits were verified and their affinity measured using NMR-based 1H–15N heteronuclear single quantum coherence (HSQC) chemical shift perturbation and fluorescence titrations. Chemical shift changes were monitored, plotted, and fitted to obtain dissociation constants (Kd). Tight binding compounds with Kd’s ranging from 6–60 μM were identified. These compounds tended to have significant polarity and negative charge, similar to the natural substrates (M5P and ATP). HSQC cross peak changes suggest that binding induces a global conformational change, such as domain closure. Compounds identified in this study serve as chemical genetic probes of human PMK, to explore pharmacology of the mevalonate pathway, as well as starting points for further drug development