A THERMODYNAMIC EQUILIBRIUM ANALYSIS OF GLUCOSE CONVERSION TO HYDROCARBONS

Deoxygenation, or removal of oxygen from oxygenates, is an important element in the hydrocarbon fuel production process from biorenewable substrates. A thermodynamic equilibrium analysis gives valuable insights on the theoretical limits of desired products when a substrate is reacted under a given set of conditions. Here we report the equilibrium composition of glucose-to-hydrocarbon system by minimizing the total Gibbs energy of the system. The system was treated as a mixture of 11 components comprised of C₆H₆, C₇H₈, C₈H₁₀ (ethyl benzene), C₈H₁₀ (xylenes), C₆H₅ –OH, CH₄, H₂O, C, CO₂, CO, and H₂. Equilibrium compositions of each species were analyzed between temperatures 300 and 1500 K and pressures 0–15 atm. It was observed that at high temperature, CO and H₂ dominate the equilibrium mixture with mole fractions of 0.597 and 0.587 respectively. At low temperatures the equilibrium mixture is dominated by CH₄, CO₂, H₂O, and carbon. The aromatic hydrocarbon composition observed at thermodynamic equilibrium was extremely small.     

The chemistry and technology of cinnamon

Cinnamon (Cinnamomum zeylanicum, Nees in Wall) is one of the world's oldest spices. Sri Lanka is the main provider of cinnamon, mainly exported as “cinnamon quills.” From a phytochemical viewpoint, cinnamon is a uniquely interesting plant. The volatile oils obtained from the bark, leaf, and root bark vary significantly in chemical composition. Each oil has a different primary constituent: cinnamaldehyde (in the bark oil), eugenol (in the leaf oil), and camphor (in the root‐bark oil). Recent studies based on techniques such as gas‐liquid chromatography and infrared spectrometry have revealed that the three oils possess the same array of monoterpene hydrocarbons in different proportions. Both gas‐liquid chromatography and quantitative infrared spectrometry have recently been used to study changes in the chemical composition in the volatiles of cultivated and wild‐growing cinnamons. As a result, some interesting biosynthetic speculations have evolved, and reliable methods of analytical assessment of quality have been developed. The technology of production of cinnamon oils has varied little from the methods introduced by the early Dutch settlers. They are based on variations on the general theme of steam distillation. Recently, new still designs have greatly enhanced the technological capability in Sri Lanka. Cinnamon bark and leaf oils form the basis of a variety of synthetically derived chemicals used in the food and cosmetic industries.     

Twist-boat conformation in graphene oxides

We have investigated the structural, electronic, and vibrational properties of graphene oxide based on first-principles density-functional calculations. A twist-boat conformation is identified as the energetically most favorable nonmetallic configuration for fully oxidized graphene. The calculated Raman G-band blue shift is in very good agreement with experimental observations. Our results provide important insight into structural and electronic characteristics that are useful for further development of graphene-based nanodevices.     

Need to Strengthen the Bridge between the Water and Energy Professionals: An Example from Sri Lanka

Sri Lanka, a developing island in the Indian Ocean, is attempting to effectively utilize the available natural resources. Though the Upper Kotmale Hydropower Project planned by energy authorities was submitted for approval as the best option, the project was to affect several scenic waterfalls. After a critical evaluation of various project alternatives, water and other professionals indicated that an option which claimed to have almost no effect on waterfalls would probably be the best option. This gave rise to a conflicting situation that resulted in a delay in project implementation. The work presented is a discussion of the evaluation of environmental impact assessment, highlighting the need to bridge the gap between energy, water and other professionals.     

Structural and electronic properties of fluorographene

The structural and electronic characteristics of fluorinated graphene are investigated based on first-principles density-functional calculations. A detailed analysis of the energy order for stoichiometric fluorographene membranes indicates that there exists prominent chair and stirrup conformations, which correlate with the experimentally observed in-plane lattice expansion contrary to a contraction in graphane. The optical response of fluorographene is investigated using the GW-Bethe-Salpeter equation approach. The results are in good conformity with the experimentally observed optical gap and reveal predominant charge-transfer excitations arising from strong electron-hole interactions. The appearance of bounded excitons in the ultraviolet region can result in an excitonic Bose-Einstein condensate in fluorographene.     

Perfluoroalkylporphyrin complexes as active catalysts for the reaction of isobutane with oxygen and the decomposition of tert-butyl hydroperoxide

A new family of metalloporphyrin complexes having perfluoroalkyl groups in the meso-positions of the ring are active catalysts for the oxidation of isobutane to tert-butyl alcohol, TBA, and for the decomposition of tert-butyl hydroperoxide to TBA. This discovery extends the limited number of meso-substituents that can be used to enhance catalytic activity and fits the postulate that groups that withdraw electrons from the porphyrin periphery give rise to active catalysts for alkane oxidation. The perfluoroalkyl groups also confer oxidative stability, hydrophobicity and lower cost to the catalyst.     

Sternal osteomyelitis

The aim of this study was to determine and compare lead concentrations in breast milk between urban and rural women. Colostrum from 51 women living in the city of Thessaloniki (exposed to increased air lead concentration, 0.54 micrograms/m3) and from 40 women living in rural areas (exposed to significantly lower air lead concentrations) was analyzed by atomic absorption spectrometry. Urban women showed slightly higher lead concentrations (mean +/- SD: 0.090 +/- 0.029 micrograms/ml) than rural women (mean +/- SD: 0.084 +/- 0.024 micrograms/ml). This difference was not statistically significant. These results suggest that the lead content of human milk is not influenced by the concentrations of this environmental pollutant in the air.     

Volatile constituents of leaf,stem and root oils of cinnamon (Cinnamomum zeylanicum)

Gas-chromatographic analysis of the volatile oils of the leaves, stem-bark and root-bark of commercial cinnamon (Cinnamomum zeylanicum), grown in Sri Lanka revealed interesting differences between them. All three oils possessed the same array of monoterpene hydrocarbons though in different proportions. The main constituents of leaf, bark and root oils are eugenol, cinnamaldehyde and camphor, respectively. Besides these, several other significant differences were observed. α-Ylangene, methyl and ethyl cinnamate in leaf oil, benzyl benzoate in bark oil and 4-terpinene-1-ol in root-bark oil are reported for the first time.     

Theobromine and caffeine content of the cocoa bean during its growth

Changes in the concentrations of caffeine and theobromine in the cocoa pod during its growth were determined. Theobromine and caffeine concentrations increased markedly after about 12 weeks from flowering to the time of harvesting. During the stage when the bean was only a mucilaginous mass, the quantity of caffeine and theobromine was negligible. Caffeine and theobromine levels in the shell, once this is formed, increased rapidly until harvest.     

Reasoning with advanced policy rules and its application to access control

This paper presents a formal framework to represent and manage advanced policy rules, which incorporate the notions of provision and obligation. Provisions are those conditions that need to be satisfied or actions that must be performed by a user or an agent before a decision is rendered, while obligations are those conditions or actions that must be fulfilled by either the user or agent or by the system itself within a certain period of time after the decision. This paper proposes a specific formalism to express provisions and obligations within a policy and investigates a reasoning mechanism within this framework. A policy decision may be supported by more than one rule-based derivation, each associated with a potentially different set of provisions and obligations (called a global PO set). The reasoning mechanism can derive all the global PO sets for each specific policy decision and facilitates the selection of the best one based on numerical weights assigned to provisions and obligations as well as on semantic relationships among them. The formal results presented in the paper hold for many applications requiring the specification of policies, but this paper illustrates the use of the proposed policy framework in the security domain only.