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We evaluate the sensitivity of the size calibrations of two commercially available, high-resolution optical particle sizers to changes in aerosol composition and complex refractive index (RI). The Droplet Measurement Technologies Ultra-High Sensitivity Aerosol Spectrometer (UHSAS) and the TSI, Inc. Laser Aerosol Spectrometer (LAS) are two commonly used instruments for measuring the portion of the aerosol size distribution with diameters larger than nominally 60–90 nm. Both instruments illuminate particles with a laser and relate the single-particle light scattering intensity and count rate measured over a wide range of angles to the size-dependent particle concentration. While the optical block geometry and flow system are similar for each instrument, a significant difference between the two models is the laser wavelength (1054 nm for the UHSAS and 633 nm for the LAS) and intensity (about 100 times higher for the UHSAS), which may affect the way each instrument sizes non-spherical or absorbing aerosols. Here, we challenge the UHSAS and LAS with laboratory-generated, mobility-size-classified aerosols of known chemical composition to quantify changes in the optical size response relative to that of ammonium sulfate (RI of 1.52+0i at 532 nm) and NIST-traceable polystyrene latex spheres (PSLs with RI of 1.59+0i at 589 nm). Aerosol inorganic salt species are chosen to cover the real refractive index range of 1.32 to 1.78, while chosen light-absorbing carbonaceous aerosols include fullerene soot, nigrosine dye, humic acid, and fulvic acid standards. The instrument response is generally in good agreement with the electrical mobility diameter. However, large undersizing deviations are observed for the low-refractive-index fluoride salts and the strongly absorbing nigrosine dye and fullerene soot particles. Polydisperse size distributions for both fresh and aged wildfire smoke aerosols from the recent Fire Influence on Regional to Global Environments Experiment and Air Quality (FIREX-AQ) and the Cloud, Aerosol, and Monsoon Processes Philippines Experiment (CAMP2Ex) airborne campaigns show good agreement between both optical sizers and contemporaneous electrical mobility sizing and particle time-of-flight mass spectrometric measurements. We assess the instrument uncertainties by interpolating the laboratory response curves using previously reported RIs and size distributions for multiple aerosol type classifications. These results suggest that, while the optical sizers may underperform for strongly absorbing laboratory compounds and fresh tailpipe emissions measurements, sampling aerosols within the atmospherically relevant range of refractive indices are likely to be sized to better than ±10 %–20 % uncertainty over the submicron aerosol size range when using instruments calibrated with ammonium sulfate.

The purpose of the present study was to examine the role of the T-786C endothelial nitric oxide synthase (eNOS) gene polymorphism on changes in renal hemodynamics and blood pressure due to Na(+) loading. Twenty-eight older (63+/-1 years), moderately obese (39+/-2 % fat) hypertensives had their glomerular filtration rate (GFR), renal plasma flow (RPF), blood pressure (BP) and plasma nitric oxide (NO(x)) levels determined after eight days of low (20 mEq) and high (200 mEq) Na(+) diets. The two Na(+) diets were separated by a 1-week washout period. Subjects were genotyped for the eNOS-786 site and were grouped on whether they were homozygous or heterozygous for the C allele (TC+CC, n=13) or only homozygous for the T allele (TT, n=15). The TC+CC genotype group had a significantly greater increase in diastolic (P=0.021) and mean arterial (P=0.018) BP and a significant decline in both RPF (P=0.007) and GFR (P=0.029) compared to the TT genotype group with Na(+) loading. Furthermore, Na(+) loading resulted in a significant (P=0.036) increase in plasma NO(x) in the TT, but not in the TC+CC genotype group as well as a trend (P=0.051) for an increase in urine NO(x) in TC+CC, but not in the TT genotype group. The increase in BP during Na(+) loading in older hypertensives was associated with the eNOS genotype and may be related to changes in renal hemodynamics due to changes in NO metabolism.

This study investigated whether an increase in microvascular surface area as a result of endurance training, which increases human skeletal muscle capillarity, would translate to greater capacity for fluid filtration compared with strength training, which does not affect capillary supply. Values for filtration capacity, Kf, derived from the slope of calf volume change, Jv, measured by venous occlusion plethysmography, against cuff pressure during a protocol of small cumulative pressure steps, were significantly higher in endurance athletes (5.78 +/- 0.88 mL min(-1) 100 mL(-1) mmHg(-1) x 10(-3), P < 0.05) than controls (3.38 +/- 0.32 mL min(-1) 100 mL(-1) mmHg(-1) x 10(-3) whereas strength-trained athletes had values similar to control (4.08 +/- 0.56 mL min(-1) 100 mL(-1) mmHg(-1) x 10(-3), ns), suggesting that surface area is important. However, when sedentary subjects underwent either a 4-week unilateral dynamic plantarflexion training programme (70% peak power, 20 min day(-1), 5 days week(-1) or a calf muscle electrical stimulation programme (8 Hz, 3 x 20 min day(-1), 5 days week(-1), neither of which caused limb blood flow to alter after training nor would be expected to increase capillarity, only the stimulation group showed a significant increase in Kf (6.68 +/- 0.62 mL min(-1) 100 mL(-1) mmHg(-1) x 10(-3) post-training vs. 3.38 +/- 0.38 pre-training, P < 0.05). This may be because stimulation enhances perfusion preferentially to glycolytic fibres, or maintains high levels of vascular endothelial growth factor (VEGF) or changes lymph clearance.

Non-diabetic first degree relatives of non-insulin-dependent diabetic (NIDDM) families are at increased risk of developing diabetes mellitus, and have been studied to identify early metabolic abnormalities. Hormone concentrations measured by specific enzyme immunoassays were assessed in non-diabetic relatives of North European extraction, and control subjects with no family history of diabetes were matched for age, sex and ethnicity. A 75-g oral glucose tolerance test was conducted and those with newly diagnosed NIDDM were excluded. Basal insulin resistance was determined by homeostasis model assessment (HOMA), and hepatic insulin clearance by C-peptide:insulin molar ratio. Relatives (n = 150) were heavier (BMI: p < 0.0001) than the control subjects (n = 152), and had an increased prevalence of impaired glucose tolerance (15 vs 3 %, p < 0.01). The relatives had increased fasting proinsulin levels and decreased C-peptide levels following the glucose load, while insulin levels were increased at all time points. To examine whether the differences in hormone levels were secondary to the differences in glucose tolerance and adiposity, we studied 100 normal glucose tolerant relatives and control subjects pair-matched for age, sex, waist-hip ratio and BMI. The differences in proinsulin levels were no longer apparent. However, the relatives remained more insulin resistant, and had decreased C-peptide levels and C-peptide:insulin ratios at all time points. In conclusion, we have identified several metabolic abnormalities in the normal glucose tolerant relatives, and propose that the decreased hepatic insulin clearance helps to maintain normoglycaemia in the face of combined insulin resistance and decreased insulin secretion. [Diabetologie (1997) 40: 1185–1190]

Electron density, temperature and parallel pressure measurements at several locations along field lines connecting the midplane scrapeoff layer (SOL) with the outer divertor are presented for both attached and partially-detached divertor cases: Ip = 1.4 MA, q95 = 4.2 and Pinput ∼ 6.7 MW under ELMing H-mode conditions. At the onset of the Partially Detached Divertor (PDD), a high density, low temperature plasma forms in the divertor SOL (divertor MARFE). The electron pressure drops by a factor of 2 between the midplane separatrix and the X-point and then an additional ∼ 3–5 times between the X-point and the outboard separatrix strike point. These results are in contrast to the attached (non-PDD) case, where electron pressure in the SOL is reduced by, at most, a factor of two between the midplane and the divertor target. Divertor MARFEs generally have only marginal adverse impact on important H-mode characteristics, such as confinement time. In fact, PDD discharges at low input power (i.e., approximately twice the L-H-mode threshold power) maintain good H-mode characteristics until a high density, low temperature plasma abruptly forms inside the separatrix near the X-point (X-point MARFE). Concurrent with the appearance of this X-point MARFE is a degradation in both energy confinement and the plasma fueling rate and an increase in the carbon impurity concentration inside the core plasma. The formation of the X-point MARFE is consistent with a thermal instability resulting from the temperature dependence of the carbon radiative cooling rate in the range ∼ 7–30 eV.

We have obtained the first measurements of n{sub e} and T{sub e} in the DIII-D divertor region with a multi-pulse (20 Hz) Divertor Thomson Scattering (DTS) system. Eight measurement locations are distributed vertically up to 21 cm above the divertor plate. Two-dimensional distributions have been obtained by sweeping the divertor plasma across the DTS measurement location. Several operating modes have been studied, including ohmic, L-mode, Elming H-mode, and Radiative Divertor operation with puffing of D{sub 2} and impurities. Mapping of the data to either the (L{sub pol}, {phi}) or (R, Z) planes with the EFIT equilibrium is used to analyze the 2D profiles. We find that in ELMing H-mode: n{sub e}, T{sub e}, and P{sub e} are relatively constant along field lines from the X-point to the divertor plate, especially near the separatrix field line. With D{sub 2} puffing, the DTS profiles indicate that T{sub e} in a large part of divertor region below the X-point is dramatically reduced from {approximately}30-40 eV in ELMing H-mode to 1-2 eV. This results in a fairly uniform low-T{sub e} divertor, with an increased electron density in the range of 2 to 4 x 10{sup 20} m{sup -3}. Detailed comparisons of the spatial profiles of n{sub e}, T{sub e}, and electron pressure P{sub e}, are presented for several operating modes. In addition, these data are compared with initial calculations from the UEDGE fluid code.

Ground-state two-proton (2p) radioactivity is a decay mode found in isotopes of elements with even atomic numbers located beyond the two-proton drip line. So far, this exotic process has been experimentally observed in a few light and medium-mass nuclides with Z less than or equal to 30. In this study, using state-of-the-art nuclear density functional theory, we globally analyze 2p radioactivity and for the first time identify 2p decay candidates in elements heavier than strontium. We predict a few cases where the competition between 2p emission and alpha decay may be observed. In nuclei above lead, the alpha decay mode is found to be dominating and no measurable candidates for the 2p radioactivity are expected., Comment: 1 page, 2 encapsulated-postscript figures; this work has been accepted for publication in Physical Review Letters

All-electron variational and diffusion quantum Monte Carlo calculations of the ground state energies of the first row atoms (Li to Ne) are reported. We use trial wavefunctions of four types: single determinant Slater-Jastrow wavefunctions; multi-determinant Slater-Jastrow wavefunctions; single determinant Slater-Jastrow wavefunctions with backflow transformations; multi-determinant Slater-Jastrow wavefunctions with backflow transformations. At the diffusion quantum Monte Carlo level and using our best trial wavefunctions we recover 99% or more of the correlation energy for Li, Be, B, C, N, and Ne, 97% for O, and 98% for F., 6 pages, 4 figures

A field trial to assess the efficacy of Bistar 80 SC as a barrier treatment of Australian military tents was conducted over 10 d at Mount Bundey Military Training Area, Northern Territory, Australia, in March 2003. Four pairs of standard eight-person tents were erected, with a single tent in each pair treated with 0.1% Bistar 80 SC as a course spray, and the remainder left as untreated control tents. Carbon dioxide-baited traps were operated in each tent nightly, and biting collections conducted over 8 nights. There was a mean increase in protection of 81% for mosquitoes entering treated tents and 90.4% increase in protection against biting of predominantly Culex annulirostris Skuse. In addition, bifenthrin applied to the military tents enhances the protection of occupants against bites from this important arbovirus vector.

Carpenter [Phys. Rev. E 61, 532 (2000)] succeeded in determining a single universal model, called the P1 model, that could describe the ellipsometric critical adsorption data from the liquid-vapor interface of four different critical binary liquid mixtures near their critical demixing temperatures. The P1 model also recently has been used to describe neutron reflectometry data from a critical liquid mixture/crystalline quartz interface. However, in another recent study, the P1 model failed to simultaneously describe x-ray reflectometry and ellipsometry data from the liquid-vapor surface of the critical mixture n -dodecane + tetrabromoethane (DT). In this paper, we resolve this discrepancy between x-ray and ellipsometric data for the DT system. At large length scales (far from the interface) the local concentration is described by the P1 model in order to correctly reproduce the temperature dependence of the ellipsometric data. Close to the interface, however, the molecular structure must be correctly accounted for in order to quantitatively explain the x-ray data. An important conclusion that arises from this study is that neutron or x-ray reflectometry is most sensitive to short-range interfacial structure, but may provide misleading information about long-range interfacial structure. Ellipsometry provides a more accurate measure of this long-range interfacial structure. Complex interfacial structures, possessing both short- and long-range structure, are therefore best studied using multiple techniques.

It is generally acknowledged that training results in capillary growth in skeletal muscle, with the extent of growth varying according to length and type of training. There is also growth of arterioles and expansion of the whole vascular bed, as indicated by increased maximal conductance. Surprisingly, in the heart, training results in capillary growth almost predominantly in young animals, while growth of arterioles and enlargement of large vessels occurs in adults, even when not accompanied by capillary growth (see Hudlicka et al. 1992). There is no doubt that the changes in capillary supply are due at least in part to growth of endothelial cells, which was demonstrated by [3H]thymidine incorporation in capillary nuclei in the hearts of animals trained by swimming (Man-dache et al. 1973). Although there is no parallel evidence in skeletal muscles, increased capillarization demonstrated either by histochemical techniques which depict specifically capillary endothelium, or by electron microscopy, thus revealing all anatomically present vessels, are the result of growth of new vessels.

The aim of the study was to evaluate an acute decrease in NEFA levels during an oral glucose tolerance test and its effects on glucose tolerance, muscle glucose uptake and muscle indirect calorimetry in ten lean non-insulin-dependent diabetic subjects. Two 75-g oral glucose tolerance tests were performed in random order. Placebo or 250 mg acipimox (to inhibit lipolysis) were administered orally 2 h before the start of the oral glucose tolerance test. Two hours after acipimox administration (time 0), non-esterified fatty acid, glycerol and 3-hydroxybutyrate levels decreased by 84, 68 and 77% respectively, compared to basal levels. Concomitantly, muscle lipid oxidation and non-oxidative glycolysis also decreased significantly. After placebo administration, non-esterified fatty acids, glycerol and 3-hydroxybutyrate and lipid oxidation increased by 29, 28, 106 and 33%, respectively (NS vs basal levels; p

Scanning tunnelling microscopy (STM) has been applied to the study, in air, of the topography of Os(bipy)2Cl2-loaded poly(4-vinylpyridine)(PVP)(bipy = 2,2′-bipyridyl) films supported on polycrystalline graphite. Two markedly different topographical features are observed on the sample surfaces before and after electrochemical cycling in aqueous sulphuric acid electrolytes. These features are characterized, respectively, by ordered domains with rows of fibrillar structure and ordered domains with rows of granular structure. Electrochemical cycling in the sulphuric acid electrolyte therefore clearly has a profound effect on the topographies of the electroactive polymer films.

Scanning tunnelling microscopy (STM) has been used to study the topographical details of the surface structure of a glassy carbon at ultra-high resolution. In addition to small, localised graphite-like domains < 50 A× 50 A in area, the STM images of the glassy carbon studied, taken in the constant-tunnel-current mode in air, are in general characterized by two topographical features: (i) a granular structure with grain sizes typically in the range 80.0–250.0 A in some surface locations and (ii) straight or curved fibrillar structures lying side by side, in other surface locations. The latter are considered to reflect the residual structure of the polymer chains initially present during processing of the material.

The existence of directional anisotropies in quasimolecular $K$-x-ray emission has been independently confirmed in experiments on the C-C, O-C, Al-Al, and Si-Al collision systems. Anisotropies ranging from zero to substantially larger values than measured by Greenberg, Davis, and Vincent for the Ni-Ni system are strongly dependent on beam energy (0.06-2 MeV/amu). The C-C and O-C anisotropies decrease with energy. The Al-Al and Si-Al anisotropies increase with energy, in accord with a dependence predicted theoretically.

A theoretical investigation of ion-induced K-shell ionization based upon perturbed-stationary-state theory is presented. Results of calculations using this theory are compared with new data for both total and differential cross sections. Total cross sections were measured for 0.3 to 2.4 MeV protons in Ti, Cr, Co, Ni, Cu and Zn. Differential cross sections were measured for 2 MeV protons in Cu and Ni and 3 MeV 3 He ++ in Cu. Comparisons of our data for the total cross section with recent data obtained by other groups and with other theoretical results are given. The overall agreement generally is to within 10% and frequently is closer.

Inelastic electron tunnelling (IET) spectra are reported for 2-hydroxycycloheptatrienone (tropolone), 8-hydroxyquinoline (oxine), 1,2-diaminoethane, 1,2-dihydroxyethane and 1-amino-2-hydroxyethane adsorbed from the vapour on to plasma-grown aluminium oxide. The mode of chemisorption of these adsorbates is discussed as are the oxide surface sites involved in the sorption process.

Crystals of CaF2 containing different concentrations of Ce3+ and Mn2+ ions were investigated by means of optical absorption and photoluminescence. The results suggest the preferential pairing of the Mn2+ ions with Ce3+ ions in tetragonal sites (i.e. sites in which the Ce3+ ion is locally compensated by an F-interstitial in a (100) direction). At these centers efficient energy transfer from Ce3+ to Mn2+ takes place. However, a different behavior is noted when the specimens are irradiated. Measurements of X-ray- induced luminescence and thermoluminescence reveal that energy transfer does not appear to play an influential role in these latter processes. Instead of tetragonal sites, other Ce3+ centers, particularly cubic and trigonal photochromic centers, appear to dominate the X-ray-induced luminescence and the thermoluminescence.

A theoretical study is described in which the region of validity of perturbed-stationary-state theory, the application of the adiabatic limit in the semiclassical approximation, is investigated for inner-shell ionization processes. Our particular interest is the proton-induced ionization probability of the K-shell. Time-dependent, perturbed basis states are constructed by means of a variational principle which minimizes the strength of excitation for an individual state as a function of projectile velocity. By using copper as a target, we estimate that the adiabatic limit is appropriate for values of ξ, the ratio of the K-shell adiabatic radius to the K-shell radius itself, less than 0.8 to 1.0. Comparisons of calculations performed using perturbed-stationary-state theory are made with recent experimental data for the proton-induced total K-shell ionization cross section at energies between 0.5 and 2.4 MeV in targets from Sc(Z = 21) to Zn(Z = 30). Overall the agreement is quite good. However, a systematic trend for perturbed-stationary-state theory to overpredict the experimental values at the lower values of ξ is found.

Inelastic electron tunneling spectroscopy has been applied to study the adsorption of a series of phenols on plasma‐grown aluminium oxide. Vapor phase doping was used and spectra recorded for o‐, m‐, p‐chlorophenol, p‐fluorophenol, p‐bromophenol, o‐, m‐, p‐cresol, and phenol. The high resolution spectra obtained at 2 K allow most of the possible modes to be identifield. The relative strengths of these modes are compared in terms of the proposed molecular orientation of the absorbates in an effort to observe the predicted directional sensitivity of the tunneling process. No systematic line intensity variation is evident, and it is postulated that for large molecules this may be because of the complexity of the motions involved in the vibrational modes. It is also suggested that the contouring of the lead electrode round the adsorbate has the important effect of obscuring the directional sensitivity of the tunneling process. An attempt has also been made further to characterize the chemical nature of the oxide and its surface.

A study of the inelastic electron tunnelling spectra (IETS) of propanoic acid, butanoic acid and octanoic acid shows that these chemisorb from the vapour on to plasma-grown aluminium oxide to give the corresponding C3, C4 and C8 surface-bound alkanoate species. The IET spectra of butanal, dodecanol, hexadecanal and octadecanal show that these, following oxidation at the oxide surface, are also adsorbed as the corresponding C4, C12, C16 and C18 alkanoates. The band intensities and band progressions present are discussed.

Absolute K-shell x-ray-production cross sections have been measured for thin-foil targets of Sc, Ti, V, Cr, Co, Ni, Cu, and Zn for incident protons with energies from 500 to 2200 keV. In order to determine the x-ray production cross sections with high precision (? 5%), particular care was necessary in the control of experimental conditions. The overall agreement of the proton-induced cross sections with recent data obtained by other workers generally is to within 10% and frequently is to within the 5% accuracy of our results. We have developed a fundamental formulation for the impact-parameter dependence of K-shell ionization based on perturbed-stationary-state theory. Good agreement is obtained between the calculations based on this theory and our measurements of both the total and differential cross sections. In addition, comparable agreement is found with the predictions of ECPSSR theory.

The photoreduction of dilute (≤10–3M) aqueous solutions of bipyridylium salts RNC5H4–C5H4NR (R = Me, Et, Prn, Bun, n-C5H11, n-C6H13, n-C7H15) by alcohols R1R2CHOH (R1= H, R2= Me, Et, Prn, Bun, and R1= R2= Me) on irradiation with light of 254 nm wavelength is investigated. Triplet excited bipyridylium dication reacts initially with the alcohol to give an exciplex, which subsequently leads to cation radical formation via hydrogen atom transfer. Halide ions exert a strong quenching effect. The lengths of the substituent alkyl chains R (in the salt), and R2(in the alcohol) greatly influence the net quantum yield of photoreduction.

We report detailed optical absorption spectra for Mn2+ in CaF2. The spectra from unirradiated samples, reported here for the first time, enable the 495‐nm luminescence emission to be clearly assigned to a transition from the first excited 4T1g (4G) level to the 6A1g (6S) ground state. On the basis of the absorption curves energy level assignments are made for all of the 4G, 4D, 4P, and 4F levels. Racah parameters are evaluated and the reduction of these from their free‐ion values, due to covalency effects, is estimated. A value of Dq=420 cm−1 is calculated and an Orgel diagram for this system is constructed. Finally, oscillator strengths for each of the transitions are estimated from the absorption spectra. The optical absorption spectra from gamma irradiated samples show a complex array of overlapping bands, most of which can be shown to be related to the presence of Mn. The thermal annealing of the bands is associated with the production of thermoluminescence at an emission wavelength of 495 nm. Althoug...

The purpose of the project is to evaluate the technical and economic feasibility of producing specific gas products via the catalytic gasification of biomass. The results of research conducted from October 1980 to November 1982 are presented. The project was comprised of laboratory studies, process development, and economic analyses. The laboratory studies were conducted to develop operating conditions and catalyst systems for generating methane-rich gas, synthesis gases, hydrogen, and carbon monoxide. The process development unit (PDU), previously used for tests at atmospheric pressure, was modified for operation at absolute pressures of up to 10 atm (1000 kPa). A program for use on a microcomputer was written to determine the effect of yield changes at elevated pressures on process economics.

In this work we study CaF2:Ce,Mn and use optical absorption, photoluminescence (excitation and emission), and x‐ray‐induced luminescence to characterize the role played by Ce in various lattice sites during these processes. The data indicate that energy transfer takes place from Ce to Mn, predominantly from Ce3+ in tetragonal sites (i.e., Ce3+‐F−int centers with C4v symmetry). There is also some evidence of transfer from higher‐order clusters of these defects. In contrast, however, we note that there is no evidence of energy transfer in x‐ray‐excited luminescence; an increase in the Ce concentration causes a decrease in the Mn2+ emission. It appears from the present investigations that, during x‐ray excitation, nonlocally compensated Ce3+ ions of cubic symmetry compete with Mn2+ ions for free electrons released during irradiation. Thus, the data indicate that tetragonal Ce3+ sites are dominant during UV excitation and give rise to energy transfer to Mn2+, whereas cubic Ce3+ sites are dominant during irrad...

A model is described for the calculation of multipeak glow curves. A set of (km+jm+2) equations are presented which describe the flow of electrons and holes between km different electron trapping levels, jm different hole trapping levels and the conduction and valence bands. The model can be applied to complex cases where glow curves result from both electron and hole transport. A computer program has been written to solve the system of equations numerically. Calculated glow curves for a number of interesting cases are presented and some other applications of the model are briefly discussed.

Calculations of the electronic stopping power for low-velocity ($vl{Z}_{1}^{\frac{2}{3}}{v}_{0}, {v}_{0}=\frac{{e}^{2}}{\ensuremath{\hbar}}$) heavy ions, based upon three models, are performed for two systems for which experimental data are available: 800-keV $^{14}\mathrm{N}^{+}$ ions incident on amorphous solid targets from carbon to tellurium and 100-keV $^{7}\mathrm{Li}^{+}$ ions incident on amorphous targets from carbon to selenium. The results of the models are compared with each other and with the experimental data. The models are found to offer qualitatively better fits to the oscillatory experimental data than the smooth curves of the Lindhard-Scharff theory, with a particular modification of the Firsov theory favored for predictive calculations. All the models, as implemented here, required a parameter to be determined by fitting the calculated curves to the experimental points.

A study of the inelastic electron tunnelling spectra (IETS) of formic acid, [2H2]formic acid, acetic acid, [2H4]acetic acid and trifluoroacetic acid shows that these chemisorb from the vapour phase on to plasma-grown aluminium oxide as surface-bound formates and acetates. Detailed vibrational mode band assignments are made and the carboxylates are deduced to be adsorbed symmetrically on, though not necessarily perpendicular to, the oxide surface. The plasma-grown oxide shows enhanced reactivity to acetaldehyde over bulk γ-alumina behaviour. Evidence is obtained for the involvement of two surface-site types in reaction with trifluoroacetic acid.

A study of the inelastic electron tunnelling spectra (IETS) of propynoic acid, propenoic acid and 3-methyl-but-2-enoic acid shows that these are chemisorbed from the vapour on to plasma-grown aluminium oxide as surface-bound carboxylate species. In the case of propynoic acid there is clear evidence for reaction of the triple bond at some of the adsorption sites. Similar considerations apply to the propenoic acid but not to the sterically more crowded 3-methyl-but-2-enoic acid. It is suggested that these surface reactions of the adsorbed carboxylate species may involve a Bronsted acid protonation of the π-electron systems present. Observed band intensities are held to be indicative of an adsorbate orientation to the surface which is close to the vertical.

Single- and multiple-electron-loss cross sections have been measured with 20-MeV ${\mathrm{Fe}}^{4+}$ on thin He, Ne, Ar, Kr, Xe, ${\mathrm{H}}_{2}$, ${\mathrm{N}}_{2}$, ${\mathrm{O}}_{2}$, C${\mathrm{H}}_{4}$, C${\mathrm{O}}_{2}$, CH${\mathrm{F}}_{3}$, C${\mathrm{F}}_{4}$, and S${\mathrm{F}}_{6}$ gaseous targets; cross-section-per-atom data for each system are presented. Cross-section-per-atom data from targets with approximately the same average atomic number indicate that both "nonadditivity" and "density" effects, depending on the final charge state of the ion, play roles in electronloss processes during projectile interactions with molecular targets. A modified Bohr formula is developed which reproduces single-electron-loss-per-atom data for atomic targets.

Luminescence measurements (photo-, X-ray-induced and thermo-), ionic thermocurrent and optical absorption data are presented on CaF2 doped with Ce and with Mn. The purpose of the study is to examine the processes of energy storage in this material following irradiation, and the subsequent release of this energy in the form of luminescence. In the Ce-doped samples Ce2+ centers and photochromic centers are known to be the major defects induced by radiation. Ionic thermocurrent data presented in this work indicate that Ce3+-F(C4v) centers are not the precursers to these defects in the dose range used, as previously suggested. The major defects induced by radiation in the Mn-doped samples are not identified. However, the data lead us to propose that the primary mechanism of thermoluminescence emission from the material involves the re-absorption of e−–Vk recombination luminescence by Ce and Mn-related defects induced by radiation. Strong competition between the Ce-related and the Mn-related defects is evident such that Mn absorption, and therefore Mn luminescence, is significantly reduced in the presence of Ce impurities. A similar, but lesser, effect on the Ce absorption and luminescence is observed as the Mn content is increased. There is no evidence of significant energy transfer from Ce to Mn in the thermoluminescence or X-ray-induced luminescence processes, in contrast to earlier beliefs. Lumineszenzmessungen (Photo-, Rontgeninduzierte- und Thermo-Lumineszenz) sowie Daten uber thermisch stimulierten Entladungsstrom und optische Absorption fur Mn- und Ce-dotiertes CaF2 werden angegeben. Der Zweck dieser Untersuchung ist, die Prozesse, mit denen dieses Material nach Bestrahlung Energie speichert und darauf diese Energie als Lumineszenz freisetzt, zu untersuchen. Es ist bekannt, das Ce2+-Zentren und photochromatische Zentren die wichtigsten der strahlungsinduzierten Storstellen in Ce-dotierten Proben sind. Die in dieser Arbeit mitgeteilten Daten zeigen in dem verwendeten Dosisbereich, das die Ce3+–F(C4v) Zentren nicht die Vorlaufer dieser Storstellen sind, wie vorgeschlagen wurde. Die wichtigsten strahlungsinduzierten Storstellen in den Mn-dotierten Proben werden nicht identifiziert. Aber aufgrund der Daten wird vorgeschlagen, das der Hauptmechanismus der Thermolumineszenz in diesem Material die Resorption von e−–Vk. Rekombinationslumineszenz von strahlungsinduzierten Ce- und Mnassoziierten Storstellen ist. Stark konkurrierende Haftprozesse zwischen den Ce- und Mn-assoziierten Storstellen treten auf, so das Mn-Absorption und deshalb Mn-Lumineszenz bei Anwesenheit von Ce-Storstellen betrachtlich abnehmen. Eine ahnliche, aber schwachere Wirkung auf die Ce-Absorption und Lumineszenz wird beobachtet, wenn der Mn-Gehalt erhoht wird. Im Gegensatz zu fruheren Meinungen gibt es keinen Beweis dafur, das betrachtlicher Energietransport von Ce zu Mn in Fallen von Thermolumineszenz oder rontgeninduzierten Lumineszenz stattfindet.

The rates of hydrogen-deuterium exchange of protons alpha to the sulphonyl group in a conformationally rigid sulphone have been measured in aqueous-DMSO. The exchange rate ratio k eq: k ax is 1·6. The greater kinetic acidity of the equatorial proton is in accord with recent MO calculations on sulphonyl carbanion stability, but does not preclude the intermediary of planar species.

A series of 1-substituted-3,5-dimethyl-4-piperidones has been prepared and the positions of cis-trans equilibria determined by NMR. The equilibrium constants for the 1-(p-substituted phenyl) compounds do not vary significantly with the para substituent and are similar to the equilibrium constant for the 1-t-butyl analogue.

Uranium ions of energies in the range 30-90 MeV from the Oak Ridge Tandem accelerator were used to measure stopping powers for C, Al, Ni, Ag, and Au foils. Foil thicknesses were determined by $\ensuremath{\alpha}$-particle energy-loss measurements. The results are compared with various theoretical predictions. Subtraction of an assumed nuclear-stopping component leaves a residual electronic stopping power which is velocity proportional but does not appear to extrapolate to the origin, in disagreement with theory. Comparisons with other ions indicate that heavier ions exhibit larger discrepancies with theory in that the velocity-proportional stopping extrapolates to zero stopping at larger values of velocity.

Hydrogenation of the title compound and its diacetate over various catalysts has been studied and the products identified. Clemmensen reduction gave several substances but none of these corresponded to a novel compound, C11H12O4, reported in the literature from this reaction and formulated as a dihydroxydiketone: this was obtained by zinc dust reduction of the title compound, and its structure was confirmed by n.m.r. spectroscopy and by chemical studies.

The Biofuels and Municipal Waste Technology Division of the U.S. Department of Energy is sponsoring studies (under Contract DE-AC06-76RL0 1830) at the Pacific Northwest Laboratory on catalytic destruction of condensible hydrocarbons (tars) in biomass-derived gases. Currently gasifiers generate a significant amount of tars in the product gases. These tars create problems with plugging in downstream equipment and with wastewater treatment.

In previous work [1] it was shown that electron capture and loss cross sections for 30–40 MeV oxygen ions in Au channels were small enough (~10-19 cm2) to preclude charge state equilibrium in crystals 1 μm thick. In fact, a large fraction of charges 8+ and 7+ passed through the crystal without any charge exchange. In this work we show that similar conditions obtain in Ag and we have measured the charge state dependence of the stopping power for 27.8 and 40 MeV 0 ions in the [110] axial channel. We find that for those ions which do not undergo charge exchange S = kq2 for charges 6+, 7+ and 8+. Other features observed in the energy spectra of the emergent ions are attributable to charge exchange in the crystal. Screening by Fermi electrons is expected to be the same for channeled and randomly penetrating ions. The results indicate that this screening is not effective in reducing the energy loss of the ion.