Looking for high energy density compounds among polynitraminecubanes

Based on fully optimized geometric structures at DFT-B3LYP/6-311G** level, we calculated electronic structures, heats of formation, strain energies, bond dissociation energies and detonation performance (detonation velocity and detonation pressure) for a series of polynitraminecubanes. Our results have shown that energy gaps of cubane derivatives are much higher than that of triaminotrinitrobenzene (TATB), which means that cubane derivatives may be more sensitive than TATB. Polynitraminecubanes have high and positive heats of formation, and a good linear relationship between heats of formation and nitramine group numbers was presented. As the number of nitramine groups in the molecule increases, the enthalpies of combustion values are increasingly negative, but the specific enthalpy of combustion values decreases. It is found that all cubane derivatives have high strain energies, which are affected by the number and position of nitramine group. The calculated bond dissociation energies of C-NHNO₂ and C-C bond show that the C-C bond should be the trigger bond in the pyrolysis process. It is found that detonation velocity (D), detonation pressure (P) and molecule density (ρ) have good linear relationship with substituented group numbers. Heptanitraminecubane and octanitraminecubane have good detonation performance over 1,3,5,7-tetranitro-1,3,5,7-tetraazacyclooctane (HMX), and they can be regarded as potential candidates of high energy density compounds (HEDCs). The results have not only shown that these compounds may be used as HEDCs, but also provide some useful information for further investigation.     

Dinitroamino benzene derivatives: a class new potential high energy density compounds

Dinitroamino benzene derivatives are designed and studied in detail with quantum chemistry method. The molecular theory density, heats of formation, bond dissociation energies, impact sensitive and detonation performance are investigated at DFT-B3LYP/6-311G** level. The results of detonation performance indicated most of the compounds have better detonation velocity and pressure than RDX and HMX. The N-N bond can be regard as the trigger bond in explosive reaction, and the bond dissociation energies of trigger bond are almost not affected by the position and number of substituent group. The impact sensitive are calculated by two different theory methods. It is found that the compounds, which can become candidates of high energy materials, have smaller H₅₀ values than RDX and HMX. It is hoped that this work can provide some basis information for further theory and experiment studies of benzene derivatives.     

Looking for alternative energy sources

With unrest in oil-exporting countries, backlashes against biofuels and photovoltaics, and a nuclear incident in Japan, the year 2011 rattled confidence in future energy supplies. The search for alternatives is all the more urgent, but some of the solutions investigated hark back to fossil fuels that we can't afford to burn.     

F-cells are preferentially distributed among high density erythrocytes

Red blood cells from normal subjects and subjects with heterocellular hereditary persistence of fatal haemoglobin and beta-thalassaemia were fractionated according to density by centrifugation on a discontinuous gradient of Stractan II. F-cells were studied by immunofluorescence and their proportion was evaluated in each separated population. This approach has permitted to show that F-cells were preferentially distributed among high density erythrocytes. This phenomenon reflects a peculiar characteristic of F-cells.     

Computational studies on polynitropurines as potential high energy density materials

As part of a search for high energy density materials (HEDMs), a series of purine derivatives with nitro groups were designed computationally. The relationship between the structures and the performances of these polynitropurines was studied. Density functional theory (DFT) at the B3LYP/6-311G** level was employed to evaluate the heats of formation (HOFs) of the polynitropurines by designing an isodesmic reaction method. Results indicated that the HOFs were influenced by the number and positions of substituent groups. Detonation properties were evaluated using the Kamlet–Jacobs equations, based on the theoretical densities and heats of formation of the polynitropurines. The relative stabilities of the polynitropurines were studied via the pyrolysis mechanism and the UB3LYP/6-311G** method. Homolysis of the ring–NO₂ bond is predicted to be the initial step in the thermal decomposition of these purine derivatives. Considering their detonation properties and relative stabilities, the tetranitropurine (D1) derivatives may be regarded as potential candidates for practical HEDCs. These results may provide useful information for further investigations.     

Nitroborazines as potential high energy materials: density functional theoretical calculations

As part of a search for new high energy density materials, we used density functional theoretical calculations to determine the thermochemical properties of various nitro-substituted borazine molecules. Optimized geometries, vibrational frequencies and spectra, and enthalpies of formation and combustion were determined for nitroborazine, dinitroborazine, trinitroborazine, and methyltrinitroborazine with substituents on either the boron atoms or the nitrogen atoms of the parent borazine ring. Our results indicate that the specific enthalpy of combustion ranged from 4 to 11 kJ g⁻¹, with increasing substitution of nitro groups lowering the energy of combustion per unit mass.     

The psychologic consequences of exposure to high density pulsed electromagnetic energy

Five albino female rats which had been trained to run a maze were exposed to 3 nanosecond pulses of electromagnetic energy which had a density of 600,000 v/m². A disturbance of the ability of the animals to perform this recently learned task was observed.The effect was found to be reversible within a period of 30 min. Possible mechanisms by which the decision making strategy of the animals was temporarily disrupted are considered. The parallelism between the conditions of this experiment and those attending the exposure of animals to lightning bolts during electrical storms is pointed out.

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Zusammenfassung Fünf weibliche Albinoratten, die darauf trainiert waren, in einem Labyrinth zu laufen, wurden 3 Nanosekunden-Impulsen elektromagnetischer Energie ausgesetzt, die eine Energie von 600.000 v/m² hatten. Es wurde eine Störung der Fähigkeit der Tiere beobachtet, diese kürzlich gelernte Aufgabe zu bewältigen. Die Wirkung war innerhalb von 30 Min. reversibel. Die verschiedenen Mechanismen, durch die die Fähigkeit der Tiere, ihre Aufgabe zu lösen, zeitweise unterbunden wurde, werden diskutiert. Auf die Parallele zwischen den Bedingungen dieses Experiments und denen bei Entladungen während elektrischer Stürme wird hingewiesen.

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Resume On a exposé cinq femelles de rats albinos à des impulsions électromagnétiques de 3 manosecondes et d'une énergie de 600.000 v/m². Ces bêtes avaient au préalable été entraînées à se mouvoir dans un labyrinthe.On a alors pu constater que les bêtes ainsi exposées perdaient la faculté de se retrouver dans le labyrinthe. L'effet de l'exposition est cependant réversible après 30 minutes.On discute les divers mécanismes par lesquels la faculté qu'ont les bêtes d'effectuer certaines tâches est momentanément supprimée. On mentionne le parallélisme existant entre les conditions de ces expériences et celles que provoquent les décharges qui se produisent pendant les orages.

     

DFT calculations on nitrodiborane compounds as new potential high energy materials

We have used DFT methods to determine the structures and thermochemistry of several nitro-substituted diborane molecules in an attempt to rate their potential as high energy materials. The properties of nitrodiborane, three isomers of dinitrodiborane, trinitrodiborane, and tetranitrodiborane were calculated using the B3LYP density functional method. Our results indicate that the absolute enthalpy of combustion decreases with increasing nitro content, in contrast with other nitro-substituted systems that have been studied previously.     

Torrefaction: a sustainable method for transforming of agri-wastes to high energy density solids (biocoal)

Reviews in Environmental Science and Bio/Technology - The depletion of fossil fuel reserves and greenhouse gas emissions led to limit the use of fossil fuels, including natural gas, coal, or...     

Two color hybridization analysis using high density oligonucleotide arrays and energy transfer dyes.

High density oligonucleotide arrays (DNA chips) have been used in two color mutational analysis of the 3.43 kb exon 11 of the hereditary breast and ovarian cancer gene BRCA1 . Two color analysis allows competitive hybridization between a reference standard and an unknown sample, improving the performance of the assay. Fluorescein and phycoerythrin dyes werepreviously used due to their compatibility with a single line 488 nm excitation source. Here we show that an alternative dye combination, containing the energy transfer dye system phycoerythrin*cy5 along with phycoerythrin, provides more evenly matched signal intensities and decreased spectral overlap between the two fluorophores, while maintaining compatibility with a 488 nm excitation source.     

Metabolic engineering of biomass for high energy density: oilseed‐like triacylglycerol yields from plant leaves

High biomass crops have recently attracted significant attention as an alternative platform for the renewable production of high energy storage lipids such as triacylglycerol (TAG). While TAG typically accumulates in seeds as storage compounds fuelling subsequent germination, levels in vegetative tissues are generally low. Here, we report the accumulation of more than 15% TAG (17.7% total lipids) by dry weight in Nicotiana tabacum (tobacco) leaves by the co‐expression of three genes involved in different aspects of TAG production without severely impacting plant development. These yields far exceed the levels found in wild‐type leaf tissue as well as previously reported engineered TAG yields in vegetative tissues of Arabidopsis thaliana and N. tabacum. When translated to a high biomass crop, the current levels would translate to an oil yield per hectare that exceeds those of most cultivated oilseed crops. Confocal fluorescence microscopy and mass spectrometry imaging confirmed the accumulation of TAG within leaf mesophyll cells. In addition, we explored the applicability of several existing oil‐processing methods using fresh leaf tissue. Our results demonstrate the technical feasibility of a vegetative plant oil production platform and provide for a step change in the bioenergy landscape, opening new prospects for sustainable food, high energy forage, biofuel and biomaterial applications.     

Distinction in the mode of receptor-mediated endocytosis between high density lipoprotein and acetylated high density lipoprotein: evidence for high density lipoprotein receptor-mediated cholesterol transfer

The interactions of high density lipoprotein (HDL) and acetylated high density lipoprotein (acetyl-HDL) with isolated rat sinusoidal liver cells have been investigated. Cellular binding of 125I-acetyl-HDL at 0 degrees C demonstrated the presence of a specific, saturable membrane-associated receptor. This receptor was affected neither by formaldehyde-treated albumin nor by low density lipoprotein modified either by acetylation or malondialdehyde, ligands known to undergo receptor-mediated endocytosis by the cells, indicating that the receptor for acetyl-HDL constitutes a distinct class among the scavenger receptors for chemically modified proteins. Parallel binding experiments using 125I-HDL also revealed the presence on these cells of a receptor for unmodified HDL. The ligand specificities of these two receptors were similar to each other except that the acetyl-HDL receptor was sensitive to polyanions such as dextran sulfate and fucoidin. Interaction of HDL with the cells at 37 degrees C was totally different from that of acetyl-HDL. Cellular binding of HDL was not accompanied by subsequent intracellular degradation of its apoprotein moiety, whereas its cholesterol moiety was significantly transferred to the cells. In contrast, acetyl-HDL was endocytosed and underwent lysosomal degradation as a holoparticle. This shift in receptor-recognition from the HDL receptor to the acetyl-HDL receptor was accomplished by acetylation of approximately 8% of the total lysine residues of HDL apoprotein. This unique difference in endocytic behavior between HDL and acetyl-HDL suggests a potential link of the HDL receptor to HDL-mediated cholesterol transfer in sinusoidal liver cells.     

Localized damage in vertebral bone is most detrimental in regions of high strain energy density

It was hypothesized that damage to bone tissue would be most detrimental to the structural integrity of the vertebral body if it occurred in regions with high strain energy density, and not necessarily in regions of high or low trabecular bone apparent density, or in a particular anatomic location. The reduction in stiffness due to localized damage was computed in 16 finite element models of 10-mm-thick human vertebral sections. Statistical analyses were performed to determine which characteristic at the damage location--strain energy density, apparent density, or anatomic location--best predicted the corresponding stiffness reduction. There was a strong positive correlation between regional strain energy density and structural stiffness reduction in all 16 vertebral sections for damage in the trabecular centrum (p < 0.05, r2 = 0.43-0.93). By contrast, regional apparent density showed a significant negative correlation to stiffness reduction in only four of the sixteen bones (p < 0.05, r2 = 0.47-0.58). While damage in different anatomic locations did lead to different reductions in stiffness (p < 0.0001, ANOVA), no single location was consistently the most critical location for damage. Thus, knowledge of the characteristics of bone that determine strain energy density distributions can provide an understanding of how damage reduces whole bone mechanical properties. A patient-specific finite element model displaying a map of strain energy density can help optimize surgical planning and reinforcement of bone in individuals with high fracture risk.     

An improved approach for predicting the density of azido compounds

In this paper, a total of 30 azido compounds were optimised with the B3LYP method of density functional theory using six basis sets (3-21G, 6-31G, 6-31G*, 6-31G**, 6-31+G** and 6-311G*) and semi-empirical PM3 and AM1 methods. The molar volumes based on the isoelectron density contour were evaluated using a Monte Carlo integration scheme (model 1) and the integral equation formalism polarised continuum model (model 2). The densities were predicted subsequently. Excellent linear correlations were found between the results obtained with the two models, and different methods had little effect on the densities calculated using model 2. Quantitative relationships were established with the calculated and experimental densities of 25 azido compounds in the training set, and were used to predict the densities of five azido compounds in the testing set. The results obtained agree well with the experimental data, and model 2 gives a better result than model 1, with root mean square errors being 0.02 and 0.03 g cm^? 3, respectively. Therefore, model 2 is a more reliable and convenient model to predict the densities of azido compounds. This approach is believed to be applicable to other kinds of compounds too.     

小球藻高密度培养

<正>小球藻(Chlorella)为绿藻门、小球藻属的单细胞绿藻。小球藻富含蛋白质、多种色素、B族维生素、必需氨基酸、微量元素和一些生物活性代谢产物,而且同时具有抗癌、抗辐射、抗感染、抗氧化、防治高血脂症、防治便秘以及骨髓抑制等一系列生理保健功能,是较为理想的保健食品。传统上小球藻的生产采用光自养培养方式,离不开光照,产量很低,限制了小球藻的开发利用。采用异养培养无需光照,同时能使细胞浓度达到较高水平,大大降低分离成本,小球藻异养培养成为人们研究的重点[1]。     

Nutrient optimization for high density biological production applications

Conclusion At the 1989 annual meeting of the U.S. Tissue Culture Associations, Ricahrd am, a leading investigator in the serum-free nutrient requirements of cultured cells, commented on the process of medium development. He noted that a survey of major media manufacturers revealed that, among the top selling mammalian cell culture media formulations, most were nearly thirty years old.This commentary is noteworthy considering the tremendous changes in cell culture understanding and derived applications which have emerged over these three decades. Fastidious cell types relatively unknown to investigators of the 1950s and 1960s are now being cultivated in defined, serum-free environments. Culture environments range from limiting dilution clonal recoveries to maintenance cultures approaching tissue densities. While research applications continue to predominate, applications of cell culture have expanded to the engineered production of biopharmaceuticals, to replacement of animal models for toxicology testing, and to the preservation, activation and expansion of human cells, tissues and organs.It is likely that future nutrient medium development will be predicated upon the design of a minimal number of defined formulations of relatively generic utility to a broad class of cell types. Analytical techniques derived from those described herein will be exploited in the user laboratory and in collaboration with the supplier to optimize the nutrient composition for the desired biological response.