While recent reports have commented on the elevated ambient levels of hazardous air pollutants (HAPs) in certain areas of Houston, relative to other cities, few studies have assessed the health effects of HAPs for Houstonians and none have evaluated the association between ambient levels of these pollutants and lymphohematopoietic cancer risk in this population. To begin to address this deficit...

A headspace gas chromatographic (GC) method was developed to determine 1,3-butadiene (1,3-BD) in simulated saliva in contact with chewing gum. The calibration graph was linear, and the limit of detection was 0.004 mg/L, which is well below the migration limit for this substance. The headspace GC method provides rapid and reliable analysis for monitoring 1,3-BD migration from chewing gum into si...

Toughening of polyamide 6 (PA6)/ Nanoclay (NC) nanocomposites with styrene-ethylene/butadiene-styrene copolymer (SEBS) using maleated styrene-ethylene/butadiene-styrene copolymer (mSEBS)/ as a compatibilizer were investigated by blending them in a co-rotating twin-screw extruder. Response surface method of experimental design was used for optimizing the material and processing parameters. Effec...

Catalytic aqueous polymerization of butadiene by the cobalt catalyst system [Co(C8H13)(C4H6)]/CS2 affords colloidally stable latices of highly crystalline syndiotactic 1,2-polybutadiene (Tm ) 190 °C, ∆Hc ) 60 J/g, Mw ∼ 105 g/mol, 97% 1,2, 3% 1,4-cis). Catalyst modification with reagents containing electrophilic carbon atoms (e.g., aromatic formamides) strongly decreases polymer crystallinity (T...

In this paper we present two new algorithms to study the extended nature of the crossing seam between electronic potential energy surfaces. The first algorithm is designed to optimize conical intersection geometries:  both minima and saddle points. In addition, this method will optimize conical intersection geometries using arbitrary geometrical constraints. We demonstrate its potential on diff...

In the title complex, [CoPd(2)(C(3)H(5))(2)(C(8)H(11))Cl(2)(C(40)H(30)P(2))]·CH(2)Cl(2), the Co(I) atom is sandwiched between the cyclo-penta-dienyl and cyclo-butadiene rings. The two diphenyl-phosphine substituents of the cyclo-butadiene ring are situated opposite to each other and bind two Pd(II) atoms, which are additionally coordinated by a chloride ion and the three C atoms of an allyl lig...

Butenes and butadiene, which are useful intermediates for the synthesis of polymers and other compounds, are synthesized traditionally by oxidative dehydrogenation (ODH) of n-butane over complex metal oxides. Such catalysts require high O2/butane ratios to maintain the activity, which leads to unwanted product oxidation. We show that carbon nanotubes with modified surface functionality efficien...

A simple model is presented for interpreting the presence of substantial second harmonic generation (SHG) activity from assemblies of centrosymmetric molecular building blocks. Using butadiene as a computationally tractable centrosymmetric model system, time-dependent Hartree-Fock calculations of the nonlinear polarizability of butadiene dimer were well-described through exciton coupling argume...

A short synthetic pathway has been developed for the synthesis of oseltamivir (1) or the enantiomer (ent-1). The intermediates and conditions for this process are summarized in Scheme 1. The synthesis provides a number of advantages: (1) use of inexpensive and abundant starting materials; (2) complete enantio-, regio-, and diastereocontrol; (3) avoidance of explosive, azide-type intermediates; ...