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Silicon wafers, covered with different thickness layers of polystyrene, were analysed by XPS. High resolution spectra of the C1s shake-up satellite, due to the π-π* transition of the aromatic ring, were compared. A shift in the shake-up binding energy represents a change in the electronic transition energy and so in the energy of the molecular orbital. This made it possible to assess and confirm an interaction between the π electrons of the phenyl ring and the silanol groups present on the surface of the silicon. Copyright © 2015 John Wiley & Sons, Ltd.

Bioarchaeological analysis of the MDM site (8DA11) in Miami, Florida (ad 400–1200) has identified human skeletal remains with lesions suggestive of and consistent with treponematosis. A population and epidemiological approach was utilised to compare the MDM site to geographically neighbouring skeletal samples from the Highland Beach mound (8PB11) (ad 600–1200) and Fort Center (8GL12) (ad 1–500/1000). These samples were then integrated with data from previous research on proliferative skeletal lesion prevalence on the Gulf Coast of Florida. Population comparisons suggest a higher prevalence of proliferative skeletal lesions in Atlantic coastal populations as opposed to the nearest sampled site from the interior (p

In March 2007, three prehistoric skeletons were excavated and analysed from Preacher's Cave on the northern aspect of the island of Eleuthera in the Bahama archipelago. The human skeletal remains represent two males and one female dating to AD 800–1300. The first is a female in the 30s with mild osteoarthritis of the joints and spine and several healed fractures who may have been an important community elder. The second is a male in the 20s with Schmorl's nodes who may have been a shaman or even a victim of interpersonal violence. The third is a male in the mid to late 20s also with marginal osteoarthritis of the joints and spine who may have been a ceremonial leader and village headman. The high incidence of carious lesions implies a cariogenic diet possibly rich in starchy foodstuffs or even fructose. The presence of grave goods and plaited mats suggest that at least two individuals may have been of high status. This study emphasises the significance of caves to Lucayan–Taino mythology, cosmology and mortuary practice. Copyright © 2010 John Wiley & Sons, Ltd.

Remarkably preserved specimens of Cowra- lepis mclachlani Ritchie, 2005 (Proc Linn Soc NSW 126:215-259) (Phyllolepida, Placodermi) represent a unique ontogenetic sequence adding to our understanding of anat- omy, function, and phylogeny among basal jawed verte- brates (gnathostomes). A systematic review demonstrates that the Phyllolepida are a subgroup of the Arthrodira. Con- sideration of visceral and neurocranial characters supports the hypothesis that placoderms are the sister group to remaining gnathostomes. Placoderms possess, as adult ple- siomorphic features, a number of characters that are only seen in the development of extant gnathostomes—a pera- morphic shift relative to placoderms. Developmental evi- dence in vertebrates leads to a revised polarity of character transitions. These include 1) hyomandibula-neurocranium and ventral parachordal-palatoquadrate articulations (ver- tebrate synapomorphies); 2) jointed pharynx, paired basi- branchials, anterior ethmoidal-palatoquadrate articulation, short trabeculae cranii, and anterior and posterior neuro- cranial fissures (gnathostome synapomorphies); and 3) fused basibranchials, dorsal palatoquadrate-neurocranium articulation, loss of the anterior neurocranial fissure, elon- gated trabeculae cranii, and transfer of the ventral para- chordal-palatoquadrate articulation to the trabeculae (crown group gnathostomes). The level of preservation in C. mclachlani provides the basis for a reinterpretation of phyl- lolepid anatomy and function. Cowralepis mclachlani pos- sesses paired basibranchials allowing the reinterpretation of the visceral skeleton in other placoderms. Mandible depression in C. mclachlani follows an osteichthyan pattern and the ventral visceral skeleton acts as a functional unit. Evidence for hypobranchial musculature demonstrates the neural crest origin of the basibranchials and that Cowrale- pis was a suction feeder. Finally, the position of the visceral skeleton relative to the neurocranium in placoderms paral- lels the condition in selachians and osteichthyans, but dif- fers in the elongation of the occiput. The cucullaris fossa of placoderms (interpreted as a site of muscle attachment) is shown to represent, in part, the parabranchial chamber. J. Morphol. 270:775-804, 2009. 2009 Wiley-Liss, Inc.

BACKGROUND. ABT-510 is a substituted nonapeptide that mimics the antiangiogenic activity of the endogenous protein thrombospondin-1 (TSP-1). The current study was designed to establish the safety of ABT-510 in the treatment of patients with advanced malignancies on a once-daily (QD) and twice-daily dosing schedule. METHODS. Patients were randomly assigned to 1 of 6 dosing regimens: 20 mg, 50mg, or 100 mg QD or 10 mg, 25 mg, or 50 mg twice daily. ABT-510 was administered by subcutaneous bolus injection in cycles of 28 days. Tumor response and disease progression were monitored at 8-week intervals by computed tomography scan or magnetic resonance imaging. RESULTS. Thirty-six patients were randomly assigned in equal numbers to the 6 study regimens, with an additional 13 patients randomized to the 10-mg-twice-daily and 50-mg-twice-daily ABT-510 regimens. The expected pharmacokinetic target was achieved at all dose levels tested. The majority of adverse events were grade 1 or 2 (according to National Cancer Institute Common Toxicity Criteria [version 2]) and were not found to be dose related. The most frequently reported adverse events that were possibly related to ABT-510 included injection site reactions, asthenia, headache, and nausea. Grade 3 events considered to possibly be related included nausea, dyspnea, bone pain, constipation, vomiting, asthenia, and chills and tremors. One partial response was observed in a patient with carcinosarcoma who received 20 mg QD. The 6-month progression-free survival rate was 6%. Approximately 42% of patients (21 of 50 patients) had stable disease for ≥3 months. CONCLUSIONS. ABT-510 can be administered at doses of 20 mg/day to 100 mg/day without significant toxicity. In the current study, minimal antitumor activity was observed, which was similar to observations in other single-agent antiangiogenic trials. Cancer 2008. © 2008 American Cancer Society.

This paper describes methods of analysis for radioactively labeled polyacrolein in solutions, powders, and on paper. The tracers, tritium and carbon-14, were used because of interferences encountered in some of the analyses. Briefly, the methods involve combustion of the sample in the Sohoniger flask, absorption of the desired product of combustion in a suitable solvent, followed by liquid scintillation counting. For tritium analysis, ethanolic toluene was the absorbent for the product water, and for carbon-14 methanolic benzylamine was used to absorb the carbon dioxide. Two sources of error in the analysis were discovered, namely, soot and dissolved oxygen. These seriously affected the accuracy and precision of the results. A filtration step followed by an equilibration with air resulted in satisfactory analyses. The use of benzylamine to absorb carbon dioxide has the added advantage of permitting the determination of the weight per cent of carbon by a simple titration with base. The advantages of the tracer method for polyacrolein are (1) specificity, (2) multiple analyses (>20 combustions per day), (3) convenience, and (4) low cost in combustion equipment.

Let P be a linear relaxation of an integer polytope Z such that the integrality gap of P with respect to Z is at most r, as verified by a polytime heuristic A, which on any positive cost function c returns an integer solution (an extreme point of Z) whose cost is at most r times the optimal cost over P. Then for any point x* in P (a fractional solution), rx* dominates some convex combination of extreme points of Z. A constructive version of this theorem is presented here, with applications to approximation algorithms, and can be viewed as a generalization of randomized rounding.

We initiated a biosystematic study of a recently discovered population of Calycadenia pauciflora in order to evaluate its cytogenetic relationship to previously characterized chromosome races of that species. Cytogenetic analyses of six or more artificially produced individuals of each of the five possible interracial hybrid combinations indicated that the new race (designated Wurlitzer) is differentiated from the other races (Elegans, Healdsburg, Pauciflora, Ramulosa, and Tehama) by the equivalent of 2-4 reciprocal chromosome translocations and in one instance apparently a pericentric inversion. Mean pollen stainability in the hybrids ranged from 13 to 26%. The floral and vegetative features of the new race are very similar to those of races Pauciflora, Ramulosa, and Tehama of C. pauciflora. We ascribe the apparent lack of single-step cytogenetic events in the evolution of the races of C. pauciflora to one or more of the following: (1) (in some cases) the occurrence of saltational chromosome reorganization; (2) extinction of or failure to detect intermediate populations in C. pauciflora; and (3) an insufficient consideration of the possibility of the existence of intermediate races in the closely related species, C. fremontii. We conclude that the C. fremontii-C. pauciflora alliance is one of the most complex and potentially instructive examples of diploid chromosome evolution in plants.

Porcine intestinal collagen (ICL), derived from processed small intestine, is used as a part of a remodelable bilaminate biosynthetic vascular prosthesis. The process for the production of ICL involves mechanical cleaning of non-crosslinked porcine intestine (NC-ICL), disinfection with peracetic acid (PA-ICL), and crosslinking with 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide hydrochloride (PA/EDC-ICL). Two model systems were investigated to evaluate the effect of these agents on the humoral response to NC-ICL. First, the antibody titers of rabbits immunized with NC-ICL, PA-ICL, and PA/EDC-ICL were determined, and second, the humoral response of canines receiving collagenous vascular implants was examined. Collagenous and noncollagenous fractions were extracted from NC-ICL, PA-ICL, and PA/EDC-ICL and separated by SDS-PAGE. PA and EDC treatment decreased the number of extractable proteins as compared to NC-ICL. Immunoblot techniques demonstrated anti-NC-ICL antibodies recognized multiple immunoreactive proteins in NC-ICL, but not in PA-ICL or PA/EDC-ICL; and rabbits immunized with NC-ICL produced higher antibody titers to ICL proteins than rabbits immunized with either PA-ICL or PA/EDC-ICL. It was, therefore, apparent that NC-ICL was more antigenic than either PA-ICL or PA/EDC-ICL. The humoral immune response of canines to PA/EDC-ICL fabricated vascular grafts was determined. At 4 weeks, 8 weeks, and 12 weeks postimplant, serum antibodies to ICL proteins or type I collagen could not be detected. These data demonstrate a reduced humoral immune response to PA/EDC-ICL. (c) 1996 John Wiley & Sons, Inc.

It is now well confirmed that the influence of temperature on the fall-off behavior of dissociation, recombination and chemically-activated reactions can be dramatic. For single-well, single-product dissociation reactions, it is customary to approximate these fall-off surfaces using extensions of Lindemann empirical expression. In this paper, We consider chemical-activation and dissociation reactions possessing multiple wells and multiple products. We show that direct approximation of the rate coefficients via Chebyshev expansions yields reliable and accurate representations of their pressure and temperature dependences, which are superior to those from a Lindemann approach to fit the form factor representing the fall-off surface. The superiority of the method is demonstrated in a study of seven channels corresponding to four different reactions important in combustion chemistry over the ranges 300-3000 K and 0.02-200 atm.

Biliary clearance (Clb) of sotalol (STL) enantiomers was assessed in anaesthetized Sprague-Dawley rats (419 +/- 9 g, mean +/- SEM, n = 4) following administration of a 10 mg kg-1 i.v. dose of the racemate. Clb for S- and R-STL (0.0675 +/- 0.0090 and 0.0662 +/- 0.0089 mL min-1 kg-1, respectively) represented approximately 0.3% of systemic clearance (Cls) values for S- and R-STL (20.4 +/- 2.2 and 20.7 +/- 2.0 mL min-1 kg-1, respectively). Bile:plasma concentration ratios at 1, 2, and 3 h post-dose were approximately 1.4, 1.3, and 1.2 for both STL enantiomers. Renal clearance (Clr) and intestinal clearance (Cli) of STL enantiomers were assessed in conscious Sprague-Dawley rats (325 g, n = 4) following administration of a 10 mg kg-1 i.v. dose of the racemate. STL enantiomers were predominantly eliminated intact in the urine: Clr for S- and R-STL (26.3 +/- 3.2 and 28.7 +/- 4.2 mL min-1 kg-1 respectively) accounted for approximately 96% of Cls for S- and R-STL (27.5 +/- 3.3 and 29.9 +/- 4.2 mL min-1 kg-1, respectively). Approximately 4% of the dose was recovered in the faeces, corresponding to Cli values of 1.16 +/- 0.17 and 1.26 +/- 0.19 mL min-1 kg-1 for S- and R-STL, respectively. Total recovery of the administered dose in urine and faeces was 99.7 +/- 0.2 and 99.8 +/- 0.5% for S- and R-STL, respectively. It is concluded from these results in the rat model that (i) STL enantiomers are predominantly eliminated intact in urine; (ii) STL enantiomers are excreted intact in bile, and to a much larger extent in the faeces, thus suggesting the presence of intestinal exsorption of STL; (iii) STL does not appear to be metabolized; and (iv) Cls, Clr, Clb, and Cli are negligibly stereoselective.

Simulated countercurrent chromatography is a continuous flow method for separation of binary mixtures or for separation of multicomponent mixtures into two fractions. Countercurrent flow is simulated by moving the feed point past several fixed adsorbent beds at a rate between the single column breakthrough time of each component. The number of columns and the location of the inlet and outlet port were varied to investigate product purity and productivity. Concentration profiles of the effluent product streams were measured. The maximum product concentration exceeds the feed concentration during part of the feed-switching cycle and drops to zero during part of the cycle. Three configurations were tested with the total number of columns varying between three and eight. For the test separation chosen, gaseous propylene and dimethyl ether on Chromosorb 101, high purity (> 99%) product streams were obtained with an optimal four-column configuration using three desorbent streams.

Pulsed laser powered homogeneous pyrolysis ( LPHP) is a technique which can be used to measure rate parameters for purely homogeneous unimolecular decomposition reactions at high temperatures (600- 1500 K). The reaction temperature in pulsed LPHP may be obtained from the speed of sound in the reacting gas, which may be measured by observing the thermal lens eFfect of the gas on a probe laser beam. The reaction time may be obtained directly from the thermal lens measurements. In this work experiments were performed using ethyl acetate (EtAc) and isopropyl chloride (2-CIPr). two reactants whose unimolecular decomposition rate parameters are well established This allowed us to assess the accuracy and precision attainable with this technique. Pulsed LPHP proved capable of providing rate parameters in good agreement with those in the literature The results for which the measured activation energies were closest to the literature values gave the temperature dependence of the rate constants as log(k,,,) = (1 2.0 -t 0 9) - 47 7 2 4.4(kcal/mo1)/2.?0?RT and log(k,~,,,,) - (13.3 ? LO) - 50.8 ? 4.8(kcal/mol)/2.?0?RT. These may be compared with the literature recommendations, log(&,,,,) = 12.6 - 48.0(kcal/mo1)/2.?0?RT and log(k,~,,,,) = 13.6 - 51 I (kcaI/rnol)/2.?03RT. In all cases the measured rate parameters agreed with the recommended values to within the error limits of the measured values Potential sources of error in the temperature measurement and the kinetic parameters are explored The expected accuracy of the experiments is assessed, and possible improvements in the experiment are suggested. 0 1996 lohn Wiley & Sons. Inc

Sotalol (STL) is an amphoteric, chiral β-adrenergic blocking drug useful in the treatment of both hypertension and ventricular arrhythmias. In the human and rat, STL enantiomers are predominantly cleared from the body by the kidney as intact drug. The renal clearance (Cl r ) of STL enantiomers substantially exceeds the glomerular filtration rate (GFR) in the human and rat. In this report, the hypothesis that STL enantiomers are excreted by an active renal transport system was investigated in the rat by coadministering racemic STL (10 mg kg -1 ) with cimetidine, an inhibitor of renal tubular secretion of organic cations. To compare the effects of short-term and sustained cimetidine exposure on STL enantiomer disposition, cimetidine was administered either as a single bolus (30 mg kg -1 , n=7) immediately prior to the STL dose, or as a 30 mg kg -1 bolus plus a 50 mg kg -1 infusion over the 6 h study period (n = 7). Blood and urine samples were collected over 6 h, during which time anaesthesia was maintained via intraperitoneal administration of pentobarbital. Cimetidine bolus and cimetidine infusion reduced STL enantiomer Cl r by 43 and 59%, respectively, compared with respective saline controls. Significant stereoselectivity was observed in the cimetidine infusion group : systemic clearance, Cl r (R>S), and AUC (S>R), although the magnitude of stereoselectivity was less than 5%. This study supports the hypothesis that STL enantiomers are predominantly cleared from the rat via a renal cationic transport mechanism, and that this system can be competitively inhibited by the presence of cimetidine.

The protein binding of sotalol (STL) enantiomers was evaluated using an ultrafiltration technique with serum from young (32 +/- 2 years, n = 5) and elderly (73 +/- 6 years, n = 5) male and female humans, and young (8 weeks, n = 4) and elderly (60 weeks, n = 3) male Sprague-Dawley rats. Serum samples were collected and immediately frozen at -20 degrees C. Within 1 week, the serum samples were thawed at room temperature, and adjusted to pH 7.4 using 0.05 M phosphate buffer, pH 5.0. Aliquots were spiked with 250 ng mL-1 and 500 ng mL-1 of each STL enantiomer, placed in ultrafiltration sets (Microsep, 30K molecular weight cut-off), capped, equilibrated to 37 degrees C, and centrifuged at 1850g for 1.5 h at 37 degrees C. Aliquots of ultrafiltrate and unspun serum were analysed for STL enantiomer concentration using a stereospecific HPLC assay. In all groups, bound fraction was less than 7% for both STL enantiomers. There were no significant differences in bound fraction between groups, or between enantiomers. Adsorption of STL enantiomers to the ultrafiltration device and membrane, evaporative loss of serum samples during centrifugation, and protein concentration in each ultrafiltrate sample were all negligible. It is concluded that the binding of STL in human and rat serum at therapeutic concentrations and physiological temperature and pH is negligible and non-stereoselective.

The use of the pulsed laser powered homogeneous pyrolysis technique for measuring unimolecular decomposition rate constants under unambiguously homogeneous conditions is investigated by numerical simulation of the experiment. The coupled partial differential equations which govern the gas dynamics and chemical kinetics are solved numerically and the results analyzed. Conditions under which rate constants can be extracted from the experimental data using a simplified analysis are determined. The effects of five sources of error in the simplified analysis are computed. A correlation is presented which may be used to correct for overestimation of the rate constant which is inherent in the simple analysis. Conditions under which the other four sources of error become negligible are presented. Overall, it is expected that this technique will be capable of routinely measuring rate constants within a factor of 2, and will do much better when a high power laser with a uniform beam profile is used and/or a well characterized thermal monitor molecule is available which decomposes with kinetic parameters close to that of the reactant being investigated. © 1994 John Wiley & Sons, Inc.

A method is described for the determination of the number average functionality and functionality distribution of polyols based on the measured intensities of relevant end groups observed in 13C NMR spectra. Longitudinal (T1) relaxation time measurements on glycerol-, trimethylolpropane-, and pentaerythritol-initiated copolymers of propylene oxide and ethylene oxide show that the slowest relaxing moiety that needs to be quantified is the vinyl CH2group of the unsaturated side product of the propoxylation reaction. A. chromium (III)-containing relaxation reagent allows the analysis to be speeded up by decreasing the relaxation times. The relative precision of the functionality measurement is ca. ±1%, while determinations of the mole percentage levels of species with different functionalities can be carried out with a precision better than ±3 mol %. © 1994 John Wiley & Sons, Inc.

A dispersionless, adsorption equilibrium, plug-flow model of a countercurrent moving-bed chromatographic separator operating at steady state is investigated. The flux of the constituents of a binary mixture is examined via concentration-phase plane plots, which reveal a complex behavior depending on a parameter [sigma], the ratio of solid- and fluid-phase flow of the mobile phase. When the model is modified by incorporating finite mass-transfer rates, axial concentration profiles exhibit behavior that is characteristic of experimental observations, rather than the predictions of the ideal model. Numerical simulations with the finite mass-transfer model reveal an optimum operating condition.

The determination of the in vitro dissolution profiles of three different modified-release formulations of (±)-verapamil were determined and compared to a reference (Calan SR). The determination of (±)-verapamil utilized a microwave-facilitated derivatization reaction with an enantiomerically pure reagent followed by measurement of drug by reversed-phase high-performance liquid chromatography (HPLC). The dissolution profile of each of the four modified-release formulations was followed for the first hour in simulated gastric fluid (pH 1.2) and then in simulated intestinal fluid (pH 7.5) for up to a total of 12 h. The resulting dissolution profiles of each modified-release formulation suggested that only one of the three test formulations had a similar dissolution to the Calan SR reference. Interestingly, the (S:R)-enantiomer ratios of two of the test products were significantly different from unity, and the third test product was also significantly different from unity if 4 out of 5 outliers were omitted. It is suggested that dissolution testing of modified-release formulations containing chiral active ingredients must be stereospecific in order to discern whether a drug-excipient interaction occurs. Additionally, it may be suggested that dissolution techniques relying more upon diffusion of medium through the tablet matrix, rather than erosion of the tablet, may accentuate enantiomeric differences in release rates. © 1993 Wiley-Liss, Inc.

Rate coefficients of the termolecular reaction were determined over the temperature range of 248–324 K and at pressures from 1 to 10 torr by time resolved mass spectrometry. CF2ClO2 radicals were generated by flash photolysis of CF2ClBr in the presence of oxygen. Their rate of decay was measured by following (CF2O2)+ fragment ions formed in the ion source. With 2 to 40 mtorr of NO2 present the dominant removal pathway is addition to form the peroxynitrate. The third order rate coefficients are wholly within the falloff over the experimental pressure range, and have a negative temperature coefficient. Rate constants for the reverse reaction, the unimolecular dissociation of CF2ClO2NO2, D. Koppenkastrop and F. Zabel, Int. J. Chem. Kinet., 23, 1 (1991) were employed to calculate equilibrium constants, from which a 600 torr value of the combination rate coefficient was obtained at each temperature. From the temperature dependence of the equilibrium constants, the average enthalpy of reaction over the experimental temperature range was found to be 106.1 ± 0.3 kJ/mol. Extrapolation of the combination rate constants to lower and higher pressures, and estimates of low and high pressure limiting rate coefficients, k0 and k∞ were done by nonlinear least squares fit of the experimental data, using the empirical Fc equations developed by Troe.

The chiral beta-blocker, sotalol (STL), is marketed as a racemic mixture. Although both STL enantiomers have equal Class III antiarrhythmic activity, beta-blocking activity has been ascribed mainly to the R-enantiomer. The pharmacokinetics of STL enantiomers were studied in young (mean age 32 +/- 3 years), healthy male volunteers after oral administration of 160 mg. Subsequent plasma and urine samples were collected over 24 hours, and STL enantiomer concentrations were determined using a stereospecific high-performance liquid chromatography assay. There were no significant differences between pharmacokinetic parameters of enantiomers. The area under the time-concentration curves (mean +/- standard deviation [SD]) were 6.95 +/- 0.85 and 6.76 +/- 1.2 (mg/L)hour for S- and R-STL, respectively. Maximal plasma concentrations of S- and R-STL were 615 +/- 167 and 619 +/- 164 ng/mL, respectively, which were obtained on average, 3.13 +/- 0.60 hours after dosing. The mean residence time (mean +/- SD) was 13.2 +/- 1.2 and 12.9 +/- 1.8 hours for S- and R-STL, respectively. Respective renal clearance values for S- and R-STL were 8.98 +/- 1.5 and 9.46 +/- 2.3 L/hour, and were approximately 1.5 times greater than creatinine clearance. Renal clearance constituted approximately 76% of the oral clearance. Although stereoselective disposition of STL was absent after racemate administration, these results should not be extrapolated to patients with significantly altered physiology, or to the pharmacokinetics of S-STL after administration of pure-S-STL.

Using magic angle spinning 19F NMR, it has been possible to identify gaseous chlorofluorocarbon (CFC) and hydrochlorofluorocarbon (HCFC) blowing agents trapped in the cells of test samples of polyurethane foam. On spinning the samples at rates greater than 10 kHz, further signals have been observed corresponding to rigidly held CFC and HCFC molecules absorbed in the solid polymer. Differences are seen between a sample taken from the centre of a foam block and a sample taken from the block edge, possibly indicating some localized decomposition of the blowing agent(s) within the solid polymer.

Rate coefficients of the termolecular reaction were determined over the temperature range of 248–324 K and at pressures from 1 to 10 torr by time resolved mass spectrometry. CF2ClO2 radicals were generated by flash photolysis of CF2ClBr in the presence of oxygen. Their rate of decay was measured by following (CF2O2)+ fragment ions formed in the ion source. With 2 to 40 mtorr of NO2 present the dominant removal pathway is addition to form the peroxynitrate. The third order rate coefficients are wholly within the falloff over the experimental pressure range, and have a negative temperature coefficient. Rate constants for the reverse reaction, the unimolecular dissociation of CF2ClO2NO2, D. Koppenkastrop and F. Zabel, Int. J. Chem. Kinet., 23, 1 (1991) were employed to calculate equilibrium constants, from which a 600 torr value of the combination rate coefficient was obtained at each temperature. From the temperature dependence of the equilibrium constants, the average enthalpy of reaction over the experimental temperature range was found to be 106.1 ± 0.3 kJ/mol. Extrapolation of the combination rate constants to lower and higher pressures, and estimates of low and high pressure limiting rate coefficients, k0 and k∞ were done by nonlinear least squares fit of the experimental data, using the empirical Fc equations developed by Troe.

Preference-avoidance tests using a modified Y-maze test apparatus were conducted with juvenile striped bass, Morone saxatilis, and steelhead (rainbow) trout, Oncorhynchus mykiss (formerly Salmo gairdneri), exposed to a refinery effluent discharged into San Francisco Bay. The test system was set up on site at the refinery, and the performance of the test system was validated using two reference materials, phenol (reference avoidant) and a mixture of amino acids (which was hoped would serve as a reference attractant). Both species of fish were tested at four effluent concentrations ranging from 0.1 to 10% with two different dilution waters, the receiving water and a known high-quality natural seawater. The results of this study indicate that juveniles of both species tended to avoid the effluent at concentrations that might be expected to occur within a short distance of the refinery outfall diffuser. At concentrations that would occur outside the zone of initial dilution, neither species of fish exhibited a preference or avoidance response to the refinery effluent.

The kinetics of the decay of hydroxyl radicals in the presence of excess acetylene were studied at pressures in the vicinity of 1 torr and at ambient temperature in a tubular discharge-flow reactor. Hydroxyl radicals were produced by the reaction of atomic hydrogen with nitrogen dioxide, H + NO2 OH + NO. The concentration of hydroxyl was followed by line absorption photometry at 308.939 nm and 308.328 nm. Second-order rate coeffcients were determined in two sets of experiments. The initial concentration ratio [C2H2]0/[OH]0 was in the range of 2.3 to 13.2 in the first set, and 14 to 125 (owing to greater hydroxyl detection sensitivity) in the second set. Values of the second-order rate coefficient obtained were nk5 = (2.9 ± 0.3) × 10−13 cm3/molec-sec in the first set, and nk5 = (2.1 ± 0.6) × 10−13 cm3/molec-sec in the second set, where n is the stoichiometric coefficient of OH. A value of the bimolecular rate constant k5 = (2.0 ± 0.6) × 10−13 cm/molec-sec is consistent with both sets of data, as well as an earlier determination.

Four cases of thyroidectomy for suspected thyroid carcinoma after previous irradiation for Hodgkin's or non-Hodgkin's lymphoma are reviewed. The patients ranged in age from 18 to 33 years at the time of thyroid surgery with an average latency period of 12 years (range, 8-20 years) from radiation therapy to thyroidectomy. All patients had a clinically palpable thyroid nodule, and pathologically showed a pattern of multiple adenomatous nodules with cytologic atypia. The microscopic changes were sufficiently striking to cause the primary pathologist to request consultation to rule out thyroid carcinoma in each case. Fine-needle aspiration was performed in one case and suggested a thyroid neoplasm. The pathologic findings are reviewed and distinction of this lesion from thyroid carcinoma is discussed.

The use of the archiannelid Dinophilus gyrociliatus O. Schmidt in short-term (7 to 10 d) life-cycle tests with reference toxicants and industrial effluents was evaluated. Culture techniques and test protocols were developed and evaluated. The life history of this archiannelid was also studied and is described. Because this species has a very short life cycle (10 d from juvenile to juvenile at 20°C and 30%+ salinity), reproductive information can be obtained during a short-term test. The results of tests with industrial effluents and reference toxicants indicate that this species is suitable for toxicity testing and appears to be quite sensitive to the industrial effluents tested in this study. The animals are easily cultured and the testing procedure requires very little time for setup and maintenance (1 to 2 h/d). It has been determined that reproductive information can be obtained during a 7-d test that starts with newly emerged juveniles.

The variational method of sensitivity analysis is applied to a recent chemical kinetic mechanism for photochemical smog. It is demonstrated that the variational method is capable of readily handling a large mechanism. The analysis can be applied to a single chemical species or to an arbitrarily large group of species contained in an objective function. Examples of the use of different objective functions are given. The variational method provides temporally distributed sensitivity coefficients. Therefore, the results are presented as a time-dependent ranking of reactions in orderof decreasing importance with respect to the objective function species. This ranking permits the time-dependent relative influence of each reaction to be readily determined by inspection. Particular attention is paid to reactions governing daytime O3 formation and nighttime NO3 and HONO formation.

An investigation of the continuous chromatographic separation of an equimolar mixture of 1,3,5-trimethylcyclohexane and 1,3,5-trimethylbenzene with a 2.4 m × 1.37 cm ID vertical countercurrent moving bed is reported. The solid adsorbent was 30 mesh Al2O3, and the separation was carried out at 200°C. Steady-state axial concentration profiles of each species were determined by withdrawing vapor samples for analysis by gas chromatography. The binary mixture was continuously fed through a port located at approximately the midpoint of the column. The relative solids and carrier gas flow rates could be adjusted so that the more strongly adsorbed trimethylbenzene was transported downward, and less strongly adsorbed trimethylcyclohexane moved upward. For low feed rates, high-purity product streams of each were obtained at the bottom and top of the separator. For sufficiently high feed rates, trimethylbenzene was transported upward as well as downward, and top product purity deteriorated. This behavior is in qualitative accord with the predictions of a dispersionless, one-dimensional flow, adsorption equilibrium model incorporating a Langmuir isotherm.

Equations for the average energy of chemically activated species are developed, and uncertainties in the various energy quantities involved are discussed. Various approaches to the energy distribution function of chemically activated species are discussed. Trial calculations on methylcyclobutane are presented.

As a candidate for future use in the National Status and Trends Program, a novel marine sediment pore water toxicity test procedure was developed and evaluated. The test procedure involves obtaining sediment pore water with a pressurized squeeze-extraction device, and then conducting a life-cycle toxicity test with the polychaete Dinophilus gyrociliatus. Recent studies have demonstrated that for certain nonpolar organic contaminants, the key route of exposure is from the interstitial (pore) water. Sediment samples were collected from 15 different stations in the San Francisco Bay area with varying amounts of contamination. The results from the San Francisco study and other studies conducted during the development of this test procedure are reported.

Tracer-pulse chromatography allows the accurate measurement of sorption isotherms even at elevated pressures and in systems with more than one solute. Vapor equilibria of normally liquid solutes are best measured by scintillation counting of a liquid in which the column effluent and the emergent radioactive pulse are absorbed. An example is the equilibrium adsorption of n-heptane by molecular sieves at 200°C. and at pressures up to 3 atm. Sorption equilibria of permanent gases are measured by use of a more conventional differential technique wherein the column effluent passes through an ion chamber. Its use is illustrated by the equilibrium adsorption of methane by activated charcoal at pressures up to 70 atm.