Mixture Of Benzene Research Articles

Computational and experimental study of molecular interaction in a ternary liquid mixture of cyclohexylamine+ethanol+benzene

In the present investigation, we undertake the study of molecular interaction in a ternary mixture of cyclohexylamine (CHA), ethanol (Eth) and benzene (B) theoretically as well as experimentally. We study the interaction between CHA dimer and complexes (Eth-CHA, B-CHA, CHA-Eth-B) theoretically using DFT (Density functional theory) with B3LYP/6-311++G(d,p) level theory in a gas phase. It includes the quantum chemical calculations of interaction energy, bond length, and identification of the intermolecular interaction from structural parameter analysis. Further, we experimentally determine the excess thermo-acoustic parameters of the mixture. For this, we have measured the ultrasonic velocity (u) and density (ρ) of the ternary mixture of cyclohexylamine+ethanol+benzene and of pure components at 303, 308 and 313 K temperature. From these experimental values of u and ρ, excess thermo-acoustic parameters have been estimated using standard relation. The variations in excess acoustic parameters with the concentration of cyclohexylamine (x 1 ) are discussed in terms of the interactions and molecular geometry of the liquid mixture. At lower concentration, weak interactions dominate while on increasing x 1 strong forces between molecules take place. The strong H-bonding interaction between CHA- ethanol molecules and molar volume differences of pure components leads to interstitial accommodation of molecules. Experimentally determined excess properties behaviour is supported by the theoretical calculation.

Performance analysis and optimization of a PEMFC-CAORC system based on 3D construction method of thermodynamic cycle

In this study, a novel proton exchange membrane fuel cell (PEMFC) system is proposed, in which a composition adjustment organic Rankine cycle (CAORC) system is integrated. The waste heat from both PEMFC stack and after-burner is recovered by CAORC system to realize the maximum output power conversion from system waste heat. Based on 3D construction method of thermodynamic cycle, the system thermodynamic model is established to evaluate the performance of the proposed PEMFC-CAORC system. The effects of PEMFC operating temperature, current density and high evaporation temperature are analyzed. The system energy and exergy efficiencies are 39.44% and 47.60% at the PEMFC operating temperature of 358 K and current density of 0.6 A cm−2. As the PEMFC operating temperature rises, its performance can be further improved, and the system energy and exergy efficiencies at 368 K reach 40.36% and 48.72%. As the PEMFC current density increases, the system net power increases while both efficiencies drop. To improve the CAORC performance specifically, the evaporation temperature in the after-burner is suggested to be high enough, and genetic algorithm is used to optimize key parameters of the CAORC. The mixture of Benzene and Toluene are the optimum zeotropic fluid type for all optimization cases investigated, while its proportion, separation dryness and evaporation temperature vary in different PEMFC operating conditions. Compared with the original results, the CAORC thermal efficiency increases by over 4% with genetic algorithm optimization.

Prospects of co‐poly(biquinoline‐hydrazide‐imide)s for separation of benzene‐isopropanol mixture via pervaporation

AbstractPoly(biquinoline dicarbohydrazide)‐co‐(bistrimelliteimide) methylene‐bisanthranylide (PQHI) and its metal‐polymer complex PQHI‐Cu+ containing several types of functional groups (hydrazide, carboxyl, amide, and imide fragments) were synthesized. Dense thin‐film membranes were prepared to study transport properties of these polymers in the separation of a benzene and isopropanol (IPA) mixture via pervaporation. Comprehensive studies of structure, physical and mechanical properties of the novel membranes were carried out. Structure of the polymer films was characterized using scanning electron microscopy. Measurements of physical and mechanical properties showed good performance capabilities of polymers as membrane materials. Transport properties of the synthesized polymers in pervaporation of benzene–IPA mixtures were characterized by determination of total flux, separation factor, as well as permeability and selectivity of the films. It was experimentally found and confirmed by quantum chemical calculations that the novel PQHI‐based membranes are benzene selective due to the presence of functional groups capable of H‐bonding. The benzene/IPA separation factor is equal to 38 for the PQHI membrane in pervaporation of the mixture containing 20 wt% of benzene.

Effects of ternary mixtures of propane-butane-hydrogen and different liquid fuels on the performance specifications of a spark ignition engine

ABSTRACT This study reports the influences of ternary fuel mixtures consisting of liquefied propane-butane-hydrogen as additives and methanol, ethanol, iso-octane, hexane, benzene, toluene and gasoline as primary fuels on the performance specifications such as variation of power, thermal efficiency, exergy efficiency and NO of a spark ignition (SI) engine by using a combustion model. Mass ratio of one kind of gas fuels has been kept constant as 50%, mass ratios of other two kinds of gas fuels have been ranged from 10 to 50%. Hydrogen addition to mixtures has parabolically affected the variation of performance characteristics. However, they have been linearly affected by propane and butane additions. Increment and reduction trends of the performance characteristics have changed depending on liquid fuel kinds. Maximum power output is observed with 50% mixture of toluene, minimum power output is revealed with 50% mixture of methanol, maximum values of thermal and exergy efficiencies are acquired with 50% butane-30%-toluene-20% hydrogen, 50% propane-20% methanol-30% hydrogen mixture provides minimum thermal efficiency, 50% propane-30% methanol-20% hydrogen mixture provides minimum exergy efficiency. The maximum NO is observed with 50% mixture of benzene. Minimum NO is acquired with 50% mixture of propane. The maximum values of power, thermal efficiency, exergy efficiency and NO formation have been obtained as 14.16 kW, 34.37%, 33.49% and 5.78E-7 mol/cm^3 respectively. Their minimum values are 6.69 kW, 28.01%, 27.54% and 3.61E-9 mol/cm^3, respectively. The results revealed that ternary fuel mixtures considerably affect the performance specifications and NO releasement of the SI engine. An Artificial Neural Network (ANN) model of the engine is constructed for a wider view. The results of the presented study can be used to assess the effects of ternary fuel mixtures on the performance characteristics and NO formation of an SI engine.

Adsorption Behavior of Pb, Cd, Ca, Al, Zn And Co Metal Ions on Cation Exchange Resin Dowex 50 Wx8 (Nh4+ Form) From Aqueous Acetone-Ammonium Propionate Media

There has a wide interest in stability of different types of ion exchange resins against ionizing radiations. The irradiation damage and stability of polystyrendigni benzene and phenolformaldehide sulphonic acid ion exchange resins was investigated by determination of the radiolytic gases. The gas analysis showed a very good linear dose dependence of the evolved hydrogen and carbon monoxide. The linearity of carbon dioxide was good for Dowex 50 WX 10 but less pronounce for zeo-carb 215. Sulphur dioxide was at least partially produced by direct action and was consumed by secondary reaction during irradiation. Kuzin et al [1] analysed radiolytic gases evolved from a carboxylic acid exchange resin. Wiely et al [2] investigated gamma radiation induce degradation of sulphonetic styrle resin cross link with 4 and 8 % m / p dinyl benzene isomer or mixtures thereof including commercial divenyle benzene have been shown loss in capacity 5-12. 8% at the radiation intensities of 290 R/hr and total dose 0.91 – 1.0 x 10-8 rad in presence of water.

Study Of Energy And Structure On Intermolecular Interactions In Organic Solvents Using Computational Chemistry Method

This study aims to determine the amount of energy, the difference in energy, the relationship between the amount of energy and the distance between compounds, and the interactions that occur in organic solvent molecules using computational chemistry methods. In determining the amount of energy and interactions that occur, computational chemistry calculations are used using NWChem software version 6.6 with the DFT method with the B3LYP hybrid function/basis set 6-31G, the calculation results are visualized using Jmol software. The results of calculations with large computations of energy for benzene are -230.62447487 KJ/mol, ethanol -154.01322923 KJ/mol, methanol -114.98816558 KJ/mol, hexane are -235.27001385 KJ/mol. Mixture of benzene and ethanol in a ratio of 1 : 1 -384.63823964 KJ/mol, 1 : 2 538.66009762 KJ/mol , and 2 : 1 - 615.26607558 KJ/mol. A mixture of benzene and methanol in a ratio of 1 : 1 -345.61255299 KJ/mol, 1 : 2 - 460.60826254 KJ/mol, and 2 : 1 -576.24044425 KJ/mol, a mixture of hexane and ethanol in a ratio of 1 : 1 - 389.28477268 KJ/mol, 1 : 2 -543.29869234 KJ/mol and 2 : 1 -624.55723290 KJ/mol. A mixture of hexane and methanol at a ratio of 1 : 1 -350.25984691 KJ/mol, 1 : 2 -465.26041654 KJ/mol and 2 : 1 -585.53373886 KJ/mole. The difference in energy is the most in a mixture of benzene and ethanol in a ratio of 1 : 2 -0.00916429 K /mol, in a mixture of benzene and methanol in a ratio of 1 : 2 - 0.00745651 KJ/mol, a mixture of hexane and ethanol in a ratio of 2 : 1 -0.00397597 KJ/mol, and a mixture of hexane and methanol in a ratio of 1 : 2 - 0.01407153 KJ/mol. and there is no relationship between the magnitude of the interaction energy of the mixture with the distance between the molecules.

Pre-design of Biphenyl Chemical Factory from Benzene with Capacity of 10.000 Ton Per Year

The design of a biphenyl chemical plant from benzene with a capacity of 10,000 tons/year will be built in Tuban, East Java with a land area of ​​10,010 m2. The raw material in the form of Benzene is obtained from Trans-Pacific Petrochemical Indotama (TPPI), Tuban. The factory is designed to operate continuously for 330 days, 24 hours per day, and requires 214 employees. Biphenyl preparation begins with reacting benzene (2,807.74 kg/hour) in a Pipe Flow Reactor (R-01) at a reactor temperature of 377 oC and a pressure of 2 atm. This reaction takes place with a conversion of 90% and is endothermic so that a Hitech heater is used to maintain the operating temperature. The products that come out of the reactor are biphenyl and hydrogen. It is then cooled and condensed in a Partial Condenser (CD-01) to a temperature of 151 oC. Then enter into Separator-02 (SP-02) to separate hydrogen from a mixture of benzene, toluene and biphenyl. Hydrogen in the gas phase as a result of the separtor. The bottom product in the form of benzene, toluene and biphenyl in the liquid phase is pumped and put into a distillation tower (MD-01) to purify the product with the bottom product in the form of biphenyl with a purity of 99.3%. The result of the distillation tower is benzene and its impurities are recycled as feed into the reactor with a temperature of 83 oC and a pressure of 1 atm. This factory requires Fixed Capital (FC) Rp. 34,341,856,338,- + US$ 4,195,836, Working Capital (WC) (Rp. 127,536,505,173,- + US$ 170,019), Manufacturing Cost (MC) (Rp. 254,092,040,390,- + US$ 816,090), and General Expenses (GE) (Rp. 33,990,417,539,- + US$ 81,609). Economic analysis shows the value of ROI before tax is 50.38 % and the value of ROI after tax is 32.75%. POT before tax is 1.65 years and POT after tax is 2.34 years. The BEP value is 43.11% and the SDP value is 23.75%. The interest rate in DCF for 10 years is 19% on average. Thus, from a technical and economic point of view, a biphenyl plant from benzene with a capacity of 10,000 tons/year is worthy of consideration.

PAH formation in the pyrolysis of benzene and dimethyl ether mixtures behind shock waves

In this work the laser-induced fluorescence (LIF) method was used to study the formation of polyaromatic hydrocarbons (PAHs) in the pyrolysis of benzene C6H6 and dimethyl ether C2H6O (DME) mixtures diluted with argon behind reflected shock waves within a temperature range of 1300–2000 K and pressures of 3.5–5.7 bar. To monitor the volume fraction of the condensed phase, laser extinction at a wavelength of 633 nm at the temperature range 1600–2500 K was measured. The LIF spectra of PAHs formed at varying temperatures and at different times relative to the onset of the pyrolysis process were recorded. It was found that the LIF spectra shift toward longer wavelengths with increasing temperature and reaction time. It has been shown that PAHs with four or more aromatic rings are the precursors of the appearance of the condensed phase. In mixtures with DME, greater amounts of small aromatics (consisting of one-two rings and fewer larger PAHs) were detected relative to benzene pyrolysis. Besides, the DME presence significantly reduced the optical density of the mixture at 633 nm, indicating a decrease in the soot yield. Modeling of PAHs and soot growth for the conditions of experiments using the modern sectional kinetic mechanism was carried out. The simulation results have demonstrated a change in PAH formation pathways that depend on fuel composition and temperature. The effect of DME on the growth of PAHs in benzene pyrolysis is both a decrease in temperature due to heat consumption during the decomposition of DME and the appearance of additional pathways for small PAHs formation and, at the same time, a decrease in the yield of heavier compounds consisting of four or more aromatic rings.

Combined dealkylation and transalkylation reaction in FCC condition for efficient conversion of light fraction light cycle oil into value-added products

The light fraction light cycle oil (LLCO) rich in alkyl-benzene and alkyl-naphthalene with short chains is expected to have a dealkylation reaction to produce value-added products. However, since the high bond energy of its side chains, low reactivity is inevitable under catalytic cracking circumstance. In this work, the catalytic cracking performance of 1,2,4,5-TeMBs, as a model molecule of LLCO, was evaluated in FCC condition. Interestingly, the benzene additive can contribute to the conversion of 1,2,4,5-TeMBs by transalkylation reaction. Based on this, we investigated the effect of benzene on the catalytic cracking of LLCO. Compared with the catalytic cracking of LLCO alone, higher reactivity of macromolecular alkyl-benzene and alkyl-naphthalene was achieved when benzene was used as an additive in LLCO. Meanwhile, a high yield of toluene was observed produced from the transalkylation reaction of benzene. Furthermore, several zeolite catalysts were evaluated for efficient conversion of a mixture of benzene and LLCO. The results indicated that the mesoporous BEA zeolite with the appropriate acidity property and mass transfer ability was regarded as the optimal catalyst given its highest yield of value-added products.

An Enhanced Non-Equilibrium Molecular Dynamics Algorithm to Simulate the Soret Coefficient in Heptane/Benzene Mixtures

In this work, the accuracy of the Soret effect was investigated at the situation of T = 303.15 K and P = 1.0 atm. The eHEX (enhanced heat exchange) algorithm and the TraPPE-UA force field were applied to simulate this thermal diffusion behavior. The equimolar mixtures of heptane isomers (n-heptane, 2-methylhexane, 3-methylhexane and 2, 3-dimethylpentane) and benzene were chosen to be the research fluids. The Soret coefficients were calculated to compare with the experimental data and other NEMD simulated results. The results showed great agreement with experimental data and a better accuracy compared to other NEMD simulated results. Moreover, the results shows that more branches may decrease the heat affinity of the component and increase the relaxation time of the thermal diffusion behavior.

Preparation and Testing of Cordierite Monolithic Catalysts for Oxidation of Aromatic Volatile Organic Compounds

This work reports the results of catalytic oxidation of aromatic volatile organic compounds (VOCs). A gaseous mixture of benzene, toluene, ethylbenzene, and o-xylene (BTEX) in nitrogen was used as representative of VOCs. Reactions were carried out in a monolithic reactor at different temperatures, with a constant initial concentration of reactants and a constant ratio of BTEX and oxidant (synthetic air). Analysis of the oxidation products was carried out on-line before and after reaction using gas chromatography. The work involves the preparation of catalysts and their application on an inert cordierite monolithic carrier, using different combinations of mixed manganese oxides (manganese with copper, iron, and nickel) and palladium as a representative of noble metals. The prepared cordierite monolithic catalysts showed great mechanical stability and high performance regarding oxidation of the mixture of aromatic compounds. High conversion values (90 %) of all components of the mixture were achieved at temperatures below 200 °C, depending on the chemical composition of the catalytic layer. A comparison with the activity of a commercial monolithic catalyst (Purelyst PH-304), which contains Pt and Pd as catalytically active components, using toluene as a model component. A comparison of the prepared manganese oxides showed that MnFeOx and MnCuOx had the best catalytic activity. When Pd was used in combination with MnFeOx in a form of a single monolith, where Pd was applied to ¼ of the overall monolith length and MnFeOx to ¾ of overall length, achieved 90 % conversions (T90) were up to 20 °C lower when compared with the same MnFeOx monolithic catalysts without Pd. Based on the comparison of the prepared ceramic monolithic catalysts with a commercial catalyst and because the comparison was made only based on toluene conversion, it was concluded that the prepared catalysts can be considered as alternatives to commercial monolithic catalysts by introducing a low concentration of Pd.

Mass Effect of Coconut Shell-derived Activated Carbon on Adsorption of Benzene, Toluene, Ethylbenzene, and Xylene in Motorcycle Emissions

The use of motorized transportation in Indonesia is now proliferating. The higher the use of motorized vehicle-based transportation in an area, the higher the potential for air pollution. One of the air pollutants is a mixture of benzene, toluene, ethylbenzene, and xylene (BTEX). This study examines the effect of coconut shell-derived activated carbon adsorbent mass which is adjusted with different thicknesses on its adsorption ability for BTEX. The adsorbent is used to adsorb the emissions of the 1990 GL-Pro motorcycle with premium fuel. The results of gas chromatography-mass spectroscopy (GC-MS) show that motor vehicle emissions contain BTEX and other hydrocarbons. ANOVA variant analysis showed that the difference in mass of activated carbon in the range of this study did not provide a significant difference in BTEX adsorption.Keywords: adsorbent; motor vehicle emissions; BTEX pollutants; coconut shell

Bulk and Confined Benzene-Cyclohexane Mixtures Studied by an Integrated Total Neutron Scattering and NMR Method

Herein mixtures of cyclohexane and benzene have been investigated in both the bulk liquid phase and when confined in MCM-41 mesopores. The bulk mixtures have been studied using total neutron scattering (TNS), and the confined mixtures have been studied by a new flow-utilising, integrated TNS and NMR system (Flow NeuNMR), all systems have been analysed using empirical potential structure refinement (EPSR). The Flow NeuNMR setup provided precise time-resolved chemical sample composition through NMR, overcoming the difficulties of ensuring compositional consistency for computational simulation of data ordinarily found in TNS experiments of changing chemical composition—such as chemical reactions. Unique to the liquid mixtures, perpendicularly oriented benzene molecules have been found at short distances from the cyclohexane rings in the regions perpendicular to the carbon–carbon bonds. Upon confinement of the hydrocarbon mixtures, a stronger parallel orientational preference of unlike molecular dimers, at short distances, has been found. At longer first coordination shell distances, the like benzene molecular spatial organisation within the mixture has also found to be altered upon confinement.

Smart thermal behavior of tripeptide leucyl-leucyl-leucine towards vapors of binary mixture of benzene and tetrachloromethane

A new method for the determination of benzene vapors in a two-component mixture was proposed. This method is based on smart behavior of L-leucyl-L-leucyl-L-leucine (LLL) crystals, which are able to remember the included benzene. This memory is revealed as the sequential endo- and exothermic effects on the DSC curve under heating of LLL powder saturated with vapors of benzene in the temperature range above the endset point of benzene release. The enthalpies of endo- and exothermic effects are proportional to the benzene content in its binary vapor mixture with tetrachloromethane used to saturate the LLL powder. The reasons of the LLL memory are explained and the possibility to control the polymorphic state of the tripeptide using organic vapors was shown. The observed specific properties of LLL tripeptide may be used for qualitative and quantitative analysis of benzene in its mixture with other organic substances.

SAFT-γ-Mie Cross-Interaction Parameters from Density Functional Theory-Predicted Multipoles of Molecular Fragments for Carbon Dioxide, Benzene, Alkanes, and Water.

Determining unlike-pair interaction parameters, whether for group contribution equation of state or molecular simulations, is a challenge for the prediction of thermodynamic properties. As the number of components and their respective complexity increase, it becomes impractical to fit all the unlike interactions. Lorentz-Berthelot combining rules work well for systems, where the main interactions are dispersion forces, but they do not account for electrostatics. In this work, we derive predictive combining rules within the SAFT-γ-Mie framework. In the resulting model, the unlike-pair interactions account for the effect of ionization energies, partial charges, dipole moments, and quadrupole moments. We then estimate these properties for molecular fragments using density functional theory calculations and demonstrate their use to obtain realistic cross-interaction energies without the need for experimental data. An open-source python package, Multipole Approach to Predictively Scale Cross-Interactions, is included to facilitate use of the methods presented in this work. A good qualitative agreement was obtained for all phase equilibria calculations of binary mixtures containing carbon dioxide with propane, hexane, benzene, and water, as well as mixtures of hexane and benzene. Finally, we discuss future improvements to our methodology, including the use of physical insights when fitting self-interaction parameters.

Modeling and Simulation of Distillation of a Binary Non-Reacting Mixture using Rate Based Approach in Packed Column under Total Reflux

Modeling and simulation of a distillation column are very important in many chemical industries where ever it requires separation or purification of a liquid mixture into its pure components. Particularly in the context of improving efficiency, process scale-up, intensification and control it requires a validated model. In this work, both experimental results and simulation results are obtained. A batch distillation equipment that consists of a reboiler, a packed column, and a top condenser is used to distill a mixture of benzene and toluene with various heat inputs to the reboiler. The distillation process in the column is modeled by an evaporation rate-based approach using Raoult’s law for driving force. This particular feature is different from the stage-wise equilibrium model. The evaporation mass transfer coefficients are obtained for benzene and toluene in lab-scale apparatus. The material balance equations for the two components are solved using a finite difference method. The distillate compositions at total reflux obtained from experiments and the simulations are compared for validating of model proportionally. Further insights are obtained in regard to throughput and distillation efficiency.

Feasible separation regions for mixtures with S-shaped distillation lines

This paper presents an approach for determining feasible separation regions for S-shaped distillation lines. There are three main assumptions: (1) the feed is a mixture of vapor and liquid in equilibrium; (2) the column has a partial or total condenser and a partial or total reboiler; and (3) the border of the feasible separation region is defined by the extreme operating modes of the distillation process. The separation region itself was constructed using a geometric model of the column, while accounting for the shape of the distillation lines. Contrary to well-known cases for C- and U-shaped distillation lines, the border of the feasible separation region for S-shaped lines is formed from a portion of a product composition multitude (i.e., the set of distillate and bottoms composition points for a column with an infinite number of stages operating at total reflux; part of a distillation limit, which demarcates the sloppy splits from the area that is not accessible by distillation; and additional segments). The feasible separation region includes additional product composition areas, which enable the design of distillation columns with fewer theoretical stages, operating under a lower reflux ratio, as demonstrated for a mixture of methyl ethyl ketone, benzene, and toluene.

Experimental study of impurity freeze-out in ternary methane + ethane + benzene mixtures with applications to LNG production

The freeze-out of impurities in LNG production can pose significant operational risks and lead to costly blockage-induced plant shutdowns. Study of ternary and higher-order mixtures, which are more analogous to LNG, present the critical tests of thermodynamic models in terms of their utility and predictive accuracy. In this work, a visual CryoSolids apparatus was upgraded to allow analytical measurements of solvent composition in multi-component systems where a solid phase is present at equilibrium. The analytical system, which included a ROLSI sampling valve and capillary together with a gas chromatograph, was successfully commissioned and used to measure melting temperatures and solvent compositions of a ternary mixture containing methane, ethane, and benzene at temperatures down to 125 K and pressures up to 6 MPa. The effect on the solubility of benzene by adding ethane to the solvent was investigated by varying the ethane mole fraction from 0 to 0.96. The resulting temperature at which benzene melted into the liquid solvent decreased from 246 K at 4.7 MPa to 125 K at 5.7 MPa. The comparison of results with the ThermoFAST model showed that it could describe the new data with a deviation less than 1 K for ethane liquid phase mole fractions from 0 <xC2< 0.5, which increased to less than 4 K for 0.85 <xC2< 0.97. This result indicates that ThermoFAST satisfactorily represents SFE conditions in LNG mixtures of industrial relevance but needs improvement to cover wider ranges of composition.

Ambient BTEX exposure and mid-pregnancy inflammatory biomarkers in pregnant African American women

Air pollution is associated with preterm birth (PTB), potentially via inflammation. We recently showed the mixture benzene, toluene, ethylbenzene, and xylene (BTEX) is associated with PTB. We examined if ambient BTEX exposure is associated with mid-pregnancy inflammation in a sample of 140 African-American women residing in Detroit, Michigan. The Geospatial Determinants of Health Outcomes Consortium study collected outdoor air pollution measurements in Detroit; these data were coupled with Michigan Air Sampling Network measurements to develop monthly BTEX concentration estimates at a spatial density of 300 m2. First trimester and mid-pregnancy BTEX exposure estimates were assigned to maternal address. Mid-pregnancy (mean 21.3 ± 3.7 weeks gestation) inflammatory biomarkers (high-sensitivity C-reactive protein, interleukin [IL]-6, IL-10, IL-1β, and tumor necrosis factor-α) were measured with enzyme immunoassays. After covariate adjustment, for every 1-unit increase in first trimester BTEX, there was an expected mean increase in log-transformed IL-1β of 0.05 ± 0.02 units (P = 0.014) and an expected mean increase in log-transformed tumor necrosis factor-α of 0.07 ± 0.02 units (P = 0.006). Similarly, for every 1-unit increase in mid-pregnancy BTEX, there was a mean increase in log IL-1β of 0.06 ± 0.03 units (P = 0.027). There was no association of either first trimester or mid-pregnancy BTEX with high-sensitivity C-reactive protein, IL-10, or IL-6 (all P > 0.05). Ambient BTEX exposure is associated with inflammation in mid-pregnancy in African-American women. Future studies examining if inflammation mediates associations between BTEX exposure and PTB are needed.

Preparation of Core-Shell Silica Microspheres with Controllable Shell Thickness for Fast High Performance Liquid Chromatography Separation of Alkyl Benzenes and Intact Proteins.

As it is difficult to prevent secondary nucleation and agglomeration during the preparation of core-shell silica microspheres, these issues have been successfully resolved in this study using template-dissolution-induced redeposition. The non-porous particles are transformed into core-shell silica microspheres (CSSMs) in the presence of cetyltrimethylammonium bromide and octyltrimethylammonium bromide under basic conditions. The shell thickness and pore sizes of the CSSMs are controlled by adjusting the etching time and molar ratio of the template, respectively. The CSSMs are modified using octadecyltrimethylammonium chloride to separate the mixture of alkyl benzenes, and a high column separation efficiency is achieved within two minutes. The CSSMs are used for the separation and analysis of proteins and the digests of bovine serum albumin. The chromatographic column packed with core-shell particles affords a significantly higher separation efficiency than the commercial column. Therefore, as a chromatographic stationary phase, these core-shell particles can potentially be used for the fast separation of proteins, small solutes, and complex samples.