Detailed Composition Information Research Articles

Molecular dynamics simulation of the effects of base oils in barium-based greases on tribological properties based on IR and GC/MS data

Twelve kinds of base oils were characterized by a series of analytical methods to obtain detailed composition and structure information. Mineral oil and poly alpha olefin oil were mainly composed of long-chain alkanes, while ester oil was mainly composed of ester compounds. Ten of the 12 base oils were selected to synthesize barium lubricating greases. Both base oils and greases were evaluated by molecular simulation, and the corresponding molecular models were constructed based on the structural information of base oils. Grease models constructed by barium 12-hydroxystearate and ester oil exhibited the largest surface adsorption energy and intermolecular interaction energy, respectively, because polar groups in lubricant tend to adsorb on metal surface and form an absorbing film. Comparing physicochemical properties of the synthesized barium lubricating greases. The temperature resistance of grease presents a positive correlation with the simulated intermolecular interaction energy.

Influence of octahedral site chemistry on the elastic properties of biotite

Brillouin light scattering spectroscopy was used along with detailed composition information obtained from electron probe microanalysis to study the influence of octahedral site chemistry on the elastic properties of biotite crystals. Elastic wave velocities for a range of directions in the AC and BC crystallographic planes were obtained for each crystal by application of the Brillouin equation with refractive indices and phonon frequencies obtained from the Becke line test and spectral peak positions, respectively. In general, velocities increase with decreasing Fe content, approach those of muscovite at low Fe concentrations. 12 of the 13 elastic constants for the full monoclinic symmetry were obtained for each crystal by fitting analytic expressions for the velocities as functions of propagation direction and elastic constants to corresponding experimental data, with the remaining constant estimated using hexagonal symmetry. Elastic constants C11, C22, and C66 are comparable to those of muscovite and show little change with Fe concentration due to strong bonding within layers. In contrast, nearly all remaining constants show a pronounced dependence on Fe content, likely due to the weak interlayer bonding. Similar behaviour is shown by elastic stability, which falls greatly as Fe concentration increases, and elastic anisotropy within the basal cleavage plane, which decreases with Fe content. This consistent dependency of all measured elastic constants on Fe content suggests that biotite elasticity is a function of octahedral site chemistry and gives a method to determine the elastic constants and elastic stability of most biotite compositions provided, Fe or Mg concentrations are known. Moreover, the good agreement between elastic constants of Fe-poor biotite and those of phlogopite obtained from DFT simulations indicate a method to predict elastic properties of biotites.

Computer-aided naphtha liquid–liquid extraction: Molecular reconstruction, sustainable solvent design and multiscale process optimization

A new integrated sustainable solvent and process design framework is proposed based on GDP (generalized disjunctive programming) to separate the naphthenic and aromatic components from naphtha. First, the detailed molecular composition information of naphtha is obtained using a molecular reconstruction model based on feasible bulk properties. Two group-based virtual molecules are then presented to express naphtha components for the liquid–liquid extraction process design. Second, four separation performance indicators and eight SHE (safety, health and environment) metrics are screened and described for the sustainable solvent design on the basis of the UNIFAC model and functional groups. The solvent structures are modelled through the improvement of the octet rule. Last, a conceptual liquid–liquid extraction process is proposed and expressed as a CAMPD (computer aided molecular and process design) optimization problem combining with the rigorous process mechanism model, sustainable solvent design model and molecular information model of naphtha. Especially, GDP is tailored to express the discrete choices in the simultaneous optimization design of solvents and processes and address the challenge of the large-scale framework solution. Compared with the process using the traditional solvent sulfolane, the content of the separated naphthenic and aromatic components is improved by 10.37%. At the same time, the sustainability is enhanced according to SHE assessment.

Combined Raman and Turbidity Probe for Real-Time Analysis of Variable Turbidity Streams.

Real-time and in situ process monitoring is a powerful tool that can empower operators of hazardous processes to better understand and control their chemical systems without increased risk to themselves. However, the application of monitoring techniques to complex chemical processes can face challenges. An example of this is the application of optical spectroscopy, otherwise capable of providing detailed chemical composition information, to processes exhibiting variable turbidity. Here, details on a novel combined Raman spectroscopy and turbidimetry probe are discussed, which advances current technology to enable flexible and robust in situ monitoring of a flowing process stream. Furthermore, the analytical approach to accurately account for both Raman signal and turbidity while quantifying chemical targets is detailed. This new approach allows for accurate analysis without requiring assumptions of stable process chemistry, which may be unlikely in applications such as waste cleanup. Through leveraging Raman and turbidity data simultaneously collected from the combined probe within chemometric models, accurate quantification of multiple chemical targets can be achieved under conditions of variable concentrations and turbidity.

Impact of Tetrabutylammonium on the Oxidation of Bromide by Ozone.

The reaction of ozone with sea-salt derived bromide is relevant for marine boundary layer atmospheric chemistry. The oxidation of bromide by ozone is enhanced at aqueous interfaces. Ocean surface water and sea spray aerosol are enriched in organic compounds, which may also have a significant effect on this reaction at the interface. Here, we assess the surface propensity of cationic tetrabutylammonium at the aqueous liquid–vapor interface by liquid microjet X-ray photoelectron spectroscopy (XPS) and the effect of this surfactant on ozone uptake to aqueous bromide solutions. The results clearly indicate that the positively charged nitrogen group in tetrabutylammonium (TBA), along with its surface activity, leads to an enhanced interfacial concentration of both bromide and the bromide ozonide reaction intermediate. In parallel, off-line kinetic experiments for the same system demonstrate a strongly enhanced ozone loss rate in the presence of TBA, which is attributed to an enhanced surface reaction rate. We used liquid jet XPS to obtain detailed chemical composition information from the aqueous-solution–vapor interface of mixed aqueous solutions containing bromide or bromide and chloride with and without TBA surfactant. Core level spectra of Br 3d, C 1s, Cl 2p, N 1s, and O 1s were used for this comparison. A model was developed to account for the attenuation of photoelectrons by the carbon-rich layer established by the TBA surfactant. We observed that the interfacial density of bromide is increased by an order of magnitude in solutions with TBA. The salting-out of TBA in the presence of 0.55 M sodium chloride is apparent. The increased interfacial bromide density can be rationalized by the association constants for bromide and chloride to form ion-pairs with TBA. Still, the interfacial reactivity is not increasing simply proportionally with the increasing interfacial bromide concentration in response to the presence of TBA. The steady state concentration of the bromide ozonide intermediate increases by a smaller degree, and the lifetime of the intermediate is 1 order of magnitude longer in the presence of TBA. Thus, the influence of cationic surfactants on the reactivity of bromide depends on the details of the complex environment at the interface.

Erratum: Quantification of Macronutrients Intake in a Thermogenetic Neuronal Screen using <em>Drosophila</em> Larvae

An erratum was issued for:Quantification of Macronutrients Intake in a Thermogenetic Neuronal Screen using Drosophila Larvae. A figure was updated. Figure 1was updated from: Figure 1: The sucrose-yeast (SY) diets used in our protocol. (A) The blue dots represent the isocaloric (248 calories/L) macronutrient balancing diets used in the feeding assay, which differ in the protein to carbohydrate (P:C) ratios: 1:1, 1:4 and 1:16. The beige dot represents the diet used to rear the experimental third-instar larvae (L3), which contained a P:C ratio of 1:2 and a caloric density of 495 calories/L. (B) Detailed composition and nutritional information of the sucrose-yeast (SY) based diets. The components are the same for all the diets: agar, sucrose and yeast. The amount in grams of the components needed to prepare 1 L of diet is shown. Note that 1% (v/v) of blue dye must be added to the macronutrient balancing diets and to the L3 rearing diet nipagin and propionic acid solutions must be added to a final concentration (v/v) of 3% and 0.3%, respectively. Please click here to view a larger version of this figure. to: Figure 1: The sucrose-yeast (SY) diets used in our protocol. (A) The blue dots represent the isocaloric (248 calories/L) macronutrient balancing diets used in the feeding assay, which differ in the protein to carbohydrate (P:C) ratios: 1:1, 1:4 and 1:16. The beige dot represents the diet used to rear the experimental third-instar larvae (L3), which contained a P:C ratio of 1:2 and a caloric density of 495 calories/L. (B) Detailed composition and nutritional information of the sucrose-yeast (SY) based diets. The components are the same for all the diets: agar, sucrose and yeast. The amount in grams of the components needed to prepare 1 L of diet is shown. Note that 1% (v/v) of blue dye must be added to the macronutrient balancing diets and to the L3 rearing diet nipagin and propionic acid solutions must be added to a final concentration (v/v) of 3% and 0.3%, respectively. Please click here to view a larger version of this figure.

From stellar composition to cancer diagnostics

Vibrational spectroscopies, including infrared (IR) and Raman, have great potential in clinical diagnostics as they can be applied to virtually any sample type, including solids, biofluids and volatiles, and they provide detailed quantitative biochemical sample composition information. However, unlike other spectroscopic techniques, such as UV/visible, IR and Raman have not yet made the leap to widespread routine clinical adoption. This article will review the principles of IR and Raman spectroscopies, focussing on aspects of these technologies that lend themselves well to clinical application. Some of the limitations of these technologies, plus important considerations for clinical use, will also be discussed. Key examples of clinical applications of the various technologies will be presented, with comment on the success of translating these from the lab to the clinic.

Viral metagenomics analysis and eight novel viral genomes identified from the Dushanzi mud volcanic soil in Xinjiang, China

Viruses are the most abundant biological entities and play significant biological roles in marine system. However, little is known about their biodiversity in mud volcanic soil, which is salty and covered with emitting sludge. In this study, we report metagenomic analysis results of viral community composition and function from the Dushanzi mud volcanic soil (named NHS) in Xinjiang, China, and provide a comparative analysis with other environmental types. We utilized metagenomes to obtain the virus data and carried out viral automatic phylogenetic and functional analyses by the metagenomics analysis server. After assembling by metaSPAdes, scaffolds were rapidly identified and annotated with the PHAge Search Tool in order to identify new phage genomes. For the ssDNA viral group, Microviridae were the most abundant viral family, which were above 95%. Other plant viruses (Geminiviridae, Nanoviridae) and animal viruses (Circoviridae, Parvoviridae) were also detected. The majority of viral significant hits belonged to Siphoviridae (80.36%). Phages, which infect bacteria, were widely distributed in the soil sample. There were eight novel viral genomes identified in the NHS virome. The two longest scaffolds were annotated to Pseudomonas aeruginosa phage YMC11 and Acinetobacter baumannii phage LZ35, respectively. Other six new viral genomes were identified as Microviridae. Comparisons of NHS virome with other published viromes revealed that the type of ecosystem mainly drove the viral community structure. This work provided detailed viral community composition and function information, which supplemented microbial community research on mud volcanoes. Importantly, we also identified eight complete viral genomes in the NHS virome which were obviously different from known viruses.

Modified molecular matrix model for predicting molecular composition of naphtha

To improve the naphtha composition prediction model based on molecular type homologous series matrix (MTHS), this paper puts forward a novel molecular matrix to characterize the naphtha composition and the normal distribution hypothesis to better describe the molecular composition distribution within each homologous series of the molecular matrix. Through prediction calculation of eight groups of naphtha samples and eight groups of gasoline samples, it is verified that the normal distribution hypothesis is more applicable than gamma distribution hypothesis for the prediction model. According to the prediction results of the samples, the restrain range of normal distribution parameters during model computing process is summarized. With the bulk properties of naphtha samples and the value range of distribution parameters as input conditions, this study utilizes the improved novel molecular matrix to predict the composition of naphtha samples. As the results show, the novel molecular matrix can predict more detailed composition information of naphtha and improve prediction accuracy with less unknown parameters.

Characterization of soluble portions from thermal dissolution of Zhaotong lignite in cyclohexane and methanol

Thermal dissolution of Zhaotong lignite in cyclohexane and methanol was conducted at 300°C for 2h. The yields of the resulting cyclohexane- and methanol-soluble portions (CHSP and MSP) are 10.1% and 24.3%, respectively. CHSP and MSP were analyzed with a gas chromatograph/mass spectrometer (GC/MS) and negative-ion electrospray ionization Fourier transform ion cyclotron resonance mass spectrometer (FTICRMS). According to analysis with GC/MS, the compounds detected in CHSP and MSP can be classified into alkanes, alkenes, arenes, arenols, anisols, ketones, esters, nitrogen-containing compounds, and sulfur-containing compounds. The most abundant group components in CHSP and MSP are arenols and arenes, respectively. The analysis with FTICRMS shows that On (n=1–6) class species with double bond equivalent (DBE) values of 1–15 are the main acidic compounds in both CHSP and MSP, and the predominant class species in CHSP and MSP are O2 and O3 class species, respectively. Arenepolyols and aromatic carboxylic acids with 1–3 rings account for most of the On class species based on DBE distributions. In addition, fatty acids are also present in CHSP and MSP. Combination of GC/MS and FTICRMS can provide detailed composition information on coal-derived liquids at the molecular level.

An experimental and kinetic modeling study on dimethyl carbonate (DMC) pyrolysis and combustion

Dimethyl carbonate (DMC) is a promising oxygenated additive or substitute for hydrocarbon fuels, because of the absence of C–C bonds and the large oxygen content in its molecular structure. To better understand its chemical oxidation and combustion kinetics, flow reactor pyrolysis at different pressures (40, 200 and 1040 mbar) and low-pressure laminar premixed flames with different equivalence ratios (1.0 and 1.5) were investigated. Mole fraction profiles of many reaction intermediates and products were obtained within estimated experimental uncertainties. From theoretical calculations and estimations, a detailed kinetic model for DMC pyrolysis and high-temperature combustion consisting of 257 species and 1563 reactions was developed. The performance of the kinetic model was then analyzed using detailed chemical composition information, primarily from the present measurements. In addition, it was examined against the chemical structure of an opposed-flow diffusion flame, relying on global combustion properties such as the ignition delay times and laminar burning velocities. These extended comparisons yielded overall satisfactory agreement, demonstrating the applicability of the present model over a wide range of high-temperature conditions.

Simulating the impacts of error in species and height upon tree volume derived from airborne laser scanning data

A key requirement of sustainable forest management is accurate, timely, and comprehensive information on forest resources, which is provided through forest inventories. In Canada, forest inventories are conventionally undertaken through the delineation and interpretation of forest stands using aerial photography, supported by data from permanent and temporary sample plots. In recent years, Airborne Laser Scanning (ALS) data have been shown to provide accurate estimates of a range of forest structural attributes. As a result, ALS has emerged as an increasingly common data source for enhanced forest inventory programs. Capture of species compositional information with ALS, based upon the nature of the data, is less reliable than structural variables, with species information typically derived from spectral or textural interpretation of aerial photography or very high spatial resolution digital imagery. Utilizing national allometric equations for the major species found in British Columbia, Canada, and a series of individual tree-level simulations, we analyzed (i) how incorrect species identification can influence individual tree volume prediction; (ii) which of the possible species substitutions result in higher volume errors; (iii) how the error in height that is typical for photogrammetry-based and ALS-based forest inventories impacts individual tree volume estimates; and (iv) the impact of combined errors in both species composition and height on overall individual tree volume estimates. Our results indicate that species information is important for volume calculations, and that the use of generic (i.e. all species) or cover-type allometric equations can lead to large errors in volume estimates. We also found that, even with a 50% error in species composition (whereby incorrect species-specific equations are substituted), volume estimates derived from species-specific allometric equations were more accurate than estimates derived from generic or cover-type equations. Our findings indicate that errors in species composition have less impact on individual tree volume estimates than errors in height measurement. The implications of these results are that, with very accurate estimates of height provided by ALS and knowledge of what dominant species is expected in a stand, accurate estimates of volume can be generated in the absence of more detailed species composition information.

Finding the Optimal Aeration Profiles and DO Profiles in a Plug-flow Biological Wastewater Treatment Reactor with A Theoretical Approach

It is a common principle that aeration to a wastewater treatment reactor performing aerobic carbon and ammonium oxidation should be minimised while satisfactory carbon and ammonium removal is achieved. The implementation of this principle in a plug-flow like aerobic reactor has so far been in an ad-hoc manner in the absence of a theoretically optimal dissolved oxygen (DO) profile. In this study, the Pontryagin Maximum Principle is applied to derive the theoretically optimal DO profile along a plug-flow aerobic reactor. While it is difficult to implement this optimisation algorithm online in practice due to the requirement of detailed wastewater composition and model parameter information, the optimal aeration profiles revealed under various conditions provide guidance to the design and operation of aeration systems. The optimal KLa and DO profiles can be applied in benchmark model to not only achieve satisfactory effluent requirements but also aeration energy is saved.

Surface X-Ray Diffraction Results on the III-V Droplet Heteroepitaxy Growth Process for Quantum Dots: Recent Understanding and Open Questions

In recent years, epitaxial growth of self-assembled quantum dots has offered a way to incorporate new properties into existing solid state devices. Although the droplet heteroepitaxy method is relatively complex, it is quite relaxed with respect to the material combinations that can be used. This offers great flexibility in the systems that can be achieved. In this paper we review the structure and composition of a number of quantum dot systems grown by the droplet heteroepitaxy method, emphasizing the insights that these experiments provide with respect to the growth process. Detailed structural and composition information has been obtained using surface X-ray diffraction analyzed by the COBRA phase retrieval method. A number of interesting phenomena have been observed: penetration of the dots into the substrate (“nano-drilling”) is often encountered; interdiffusion and intermixing already start when the group III droplets are deposited, and structure and composition may be very different from the one initially intended.

Reactive transport modeling for CO 2 geological sequestration

One way to reduce carbon dioxide (CO 2) releases to the atmosphere, is to capture it from power plants and then inject it into deep geological formations. Understanding water-gas-mineral reactions is the core of assessing the long term storage and risks in geological sequestration. Because of various limitations of laboratory and field tests, reactive transport modeling has been one important supplementary or independent tool to study the water–gas–mineral reactions at different components of geological sequestration. In this paper, we reviewed the applications of reactive transport modeling to three aspects of CO 2 geological sequestration: the behavior of CO 2 in storage formation, the storage security issues related to caprock integrity or wellbore cement degradation, and the change of the shallow groundwater in response to the potential leakage of CO 2. Key finding are summarized and further research needs are identified. The lack of the detailed mineralogical composition information at the storage formation, caprock and overlying aquifers is currently the first obstacle for quantitative prediction of geochemical evolution. The thermodynamic properties of relevant minerals under high temperature and pressure have to be refined. Reliable reaction rates of minerals dissolution/precipitation at field are still the bottle neck of the calculating the long term mineral trapping of CO 2. Issues related to relatively fast reactions such sorption and ion exchange need special attention when the impact of CO 2 leakage on shallow groundwater was evaluated. The role of organic compounds in water-gas-mineral reactions needs further study.

Accurate calculations of the WIMP halo around the Sun and prospects for its gamma-ray detection

Galactic weakly interacting massive particles (WIMPs) may scatter off solar nuclei to orbits gravitationally bound to the Sun. Once bound, the WIMPs continue to lose energy by repeated scatters in the Sun, eventually leading to complete entrapment in the solar interior. While the density of the bound population is highest at the center of the Sun, the only observable signature of WIMP annihilations inside the Sun is neutrinos. It has been previously suggested that although the density of WIMPs just outside the Sun is lower than deep inside, gamma rays from WIMP annihilation just outside the surface of the Sun, in the so called WIMP halo around the Sun, may be more easily detected. We here revisit this problem using detailed Monte Carlo simulations and detailed composition and structure information about the Sun to estimate the size of the gamma-ray flux. Compared to earlier simpler estimates, we find that the gamma-ray flux from WIMP annihilations in the solar WIMP halo would be negligible; no current or planned detectors would be able to detect this flux.

Integration of Satellite Imagery and Forest Inventory in Mapping Dominant and Associated Species at a Regional Scale

To achieve the overall objective of restoring natural environment and sustainable resource usability, each forest management practice effect needs to be predicted using a simulation model. Previous simulation efforts were typically confined to public land. Comprehensive forest management practices entail incorporating interactions between public and private land. To make inclusion of private land into management planning feasible at the regional scale, this study uses a new method of combining Forest Inventory and Analysis (FIA) data with remotely sensed forest group data to retrieve detailed species composition and age information for the Missouri Ozark Highlands. Remote sensed forest group and land form data inferred from topography were integrated to produce distinct combinations (ecotypes). Forest types and size classes were assigned to ecotypes based on their proportions in the FIA data. Then tree species and tree age determined from FIA subplots stratified by forest type and size class were assigned to pixels for the entire study area. The resulting species composition map can improve simulation model performance in that it has spatially explicit and continuous information of dominant and associated species, and tree ages that are unavailable from either satellite imagery or forest inventory data. In addition, the resulting species map revealed that public land and private land in Ozark Highlands differ in species composition and stand size. Shortleaf pine is a co-dominant species in public land, whereas it becomes a minor species in private land. Public forest is older than private forest. Both public and private forests have deviated from historical forest condition in terms of species composition. Based on possible reasons causing the deviation discussed in this study, corresponding management avenues that can assist in restoring natural environment were recommended.

Separation and identification of neisserial lipooligosaccharide oligosaccharides using high-performance anion-exchange chromatography with pulsed amperometric detection

We determined the optimal conditions for high-performance anion-exchange chromatography with pulsed amperometric detection (HPAE-PAD) of oligosaccharides (OS) released from neisserial lipooligosaccharides (LOS) by mild acid hydrolysis. We efficiently obtained detailed composition, sequence, and linkage information about high M r LOS. We found that HPAE-PAD can discriminate isobaric (same M r) molecules of different structure, for example, nLc 4 and Gb 4, distinguish α from β chain extensions, and determine the number of phosphoethanolamine (PEA) substituents. HPAE-PAD provided quantitative information that could be used to compare the relative abundances of OS. We used HPAE-PAD to identify all of the known LOS α chain antennae. When used with antibody-binding profiles and exoglycosidase digestion results, HPAE-PAD can provide nearly complete structures rapidly.

Laser induced sodium fluorescence measurements in a turbulent propane diffusion flame

A cw laser induced fluorescence technique has been employed to make spatially (0.15 mm3) and temporally (DC to 10 kHz) resolved measurements on trace quantities of Na ( Lack of simultaneous measurements of temperature and/or another scalar introduces an uncertainty of up to ±30% in the fluorescence yield and hence in the local atomic Na number density. Estimates of total Na, necessary if the data are to be interpreted in terms of a conserved scalar, are inaccessible in this flame, except perhaps near the flame front, without detailed local composition and temperature information. The fluorescence data have been analysed to obtain statistical information, including power spectra and probability density functions (pdfs). The latter have been compared qualitatively to pdfs of temperature obtained by other workers in similar flames. Future experimental work applying LIFS in combustion is discussed briefly.