I. The rate and mechanism of the vapor-phase reaction between water and parts-per-million concentrations of nitrogen dioxide. II. The rate and mechanism of the air oxidation of parts-per-million concentrations of nitric oxide in the presence of water vapor.

<p>Part I</p> <p>A study of the thermal reaction of water vapor and parts-per-million concentrations of nitrogen dioxide was carried out at ambient temperature and at atmospheric pressure. Nitric oxide and nitric acid vapor were the principal products. The initial rate of disappearance of nitrogen dioxide was first order with respect to water vapor and second order with respect to nitrogen dioxide. An initial third-order rate constant of 5.5 (�� 0.29) x 10⁴ liter² mole^-2 sec^-1 was found at 25��C. The rate of reaction decreased with increasing temperature. In the temperature range of 25��C to 50��C, an activation energy of -978 (�� 20) calories was found.</p> <p>The reaction did not go to completion. From measurements as the reaction approached equilibrium, the free energy of nitric acid vapor was calculated. This value was -18.58 (�� 0.04) kilocalories at 25��C.</p> <p>The initial rate of reaction was unaffected by the presence of oxygen and was retarded by the presence of nitric oxide. There were no appreciable effects due to the surface of the reactor. Nitric oxide and nitrogen dioxide were monitored by gas chromatography during the reaction.</p> <p>Part II</p> <p>The air oxidation of nitric oxide, and the oxidation of nitric oxide in the presence of water vapor, were studied in a glass reactor at ambient temperatures and at atmospheric pressure. The concentration of nitric oxide was less than 100 parts-per-million. The concentration of nitrogen dioxide was monitored by gas chromatography during the reaction.</p> <p>For the dry oxidation, the third-order rate constant was 1.46 (�� 0.03) x 10⁴ liter² mole^-2 sec^-1 at 25��C. The activation energy, obtained from measurements between 25��C and 50��C, was -1.197 (��0.02) kilocalories.</p> <p>The presence of water vapor during the oxidation caused the formation of nitrous acid vapor when nitric oxide, nitrogen dioxide and water vapor combined. By measuring the difference between the concentrations of nitrogen dioxide during the wet and dry oxidations, the rate of formation of nitrous acid vapor was found. The third-order rate constant for the formation of nitrous acid vapor was equal to 1.5 (�� 0.5) x 10⁵ liter² mole^-2 sec^-1 at 40��C. The reaction rate did not change measurably when the temperature was increased to 50��C. The formation of nitric acid vapor was prevented by keeping the concentration of nitrogen dioxide low.</p> <p>Surface effects were appreciable for the wet tests. Below 35��C, the rate of appearance of nitrogen dioxide increased with increasing surface. Above 40��C, the effect of surface was small. </p>

An��lise de polimorfismos e de express��o do gene p16INK4a em neoplasias cervicais

O c��ncer de colo do ��tero �� o segundo carcinoma mais frequente em mulheres no mundo e um dos c��nceres femininos mais incidentes no Brasil. Em les��es pr��-malignas e malignas do colo uterino, a prote��na p16INK4a, que participa do controle do ciclo celular, apresenta um aumento consider��vel de sua express��o, devido possivelmente �� presen��a de oncoprote��nas do papilomav��rus humano (HPV). Dois polimorfismos no gene p16INK4a, p16 500C>G e p16 540C>T, est��o localizados na regi��o 3 n��o traduzida (3UTR), que est�� envolvida na regula����o p��s-transcricional da express��o g��nica. O objetivo deste estudo foi avaliar poss��veis associa����es entre os polimorfismos p16 500C>G e p16 540C>T e o desenvolvimento de neoplasias cervicais e/ou a severidade das les��es, considerando os n��veis de express��o da prote��na p16INK4a nas les��es cervicais e certos fatores de risco cl��ssicos para o c��ncer cervical, incluindo a infec����o pelo HPV. Para isso, foram selecionadas 567 mulheres residentes no Rio de Janeiro, 319 com citologia cervical alterada (grupo de casos) e 248 sem hist��ria pr��via de altera����o citol��gica do colo uterino (grupo de compara����o). Amostras de sangue perif��rico de todas as participantes foram utilizadas na an��lise molecular dos polimorfismos p16 500C>G e p16 540C>T atrav��s da t��cnica de PCR-RFLP (rea����o em cadeia da polimerase - polimorfismo de comprimento de fragmento de restri����o), usando as enzimas de restri����o MspI e HaeIII, respectivamente. A express��o da prote��na p16INK4a em 137 bi��psias de mulheres pertencentes ao grupo de casos foi avaliada por imunohistoqu��mica. A detec����o de DNA do HPV em c��lulas cervicais foi feita em todas as amostras do grupo de compara����o e em 194 amostras do grupo de casos pela t��cnica de PCR, usando dois pares de oligonucleot��deos, MY09/MY11 e GP05+/GP06+. Os dois grupos de estudo se encontram em equil��brio de Hardy-Weinberg. As distribui����es genot��picas para p16 500C>G e p16 540C>T e as distribui����es de combina����es haplot��picas nos dois grupos n��o apresentaram diferen��as significativas. A an��lise do subgrupo HSIL+c��ncer (casos com les��o intraepitelial de alto grau ou carcinoma invasivo) em compara����o com o subgrupo LSIL (casos com les��o intraepitelial de baixo grau) revelou diferen��a significativa entre as distribui����es das combina����es haplot��picas (p = 0,036) e diferen��as marginais entre as distribui����es genot��picas para p16 500C>G (p = 0,071) e p16 540C>T (p = 0,051). O alelo p16 540G, em heterozigose ou homozigose (OR = 1,91, IC 95% = 1,08-3,37), e a combina����o haplot��pica p16 500C-540C 500G-540C (OR = 2,34, IC 95% = 1,202-4,555) mostraram-se associados com a severidade da les��es cervicais. J�� o gen��tipo p16 540T/T (OR = 0,25, IC 95% = 0,08-0,79), e a combina����o haplot��pica p16 500C-540T 500C-540T (OR = 0,27, IC 95% = 0,088-0,827) exibiram papel protetor contra o desenvolvimento de les��es mais severas. As an��lises de intera����o entre os polimorfismos de p16INK4a e a express��o de p16 ou a infec����o pelo HPV foram comprometidas pelo n��mero reduzido de amostras analisadas. N��o se observou qualquer intera����o entre os polimorfismos estudados e os fatores de risco cl��ssicos para o c��ncer de colo uterino. Nossos resultados apontam para a import��ncia dos polimorfismos do gene p16INK4a como marcadores de severidade da neoplasia cervical.

Individual growth and seasonal cycle of Daphnia middendorffiana in an Alpine lake [Translation from: Memorie dell'Istituto Italiano di Idrobiologia Dott.Marco de Marchi 26 41-83, 1970]

The problem of the peculiar reproductive biology of the cladoceran Daphnia middendorffiana is investigated from a cytological viewpoint, and by direct observation the meiotic phenomena of the eggs both subitaneous and resting is studied. and during maturation, the true mechanism of the succession of reproductive phases of different ecological significance. Samples were collected in the Italian Alpine Lake of Campo 4��.

The role of ciliates in the pelagic life cycle of the Mediterranean [Translation from: Rapports et Proces Verbaux des Reunions-Conseil International pour l'Exploration de la Mer 17, 511-512, 1963]

During hydrographic and plankton studies carried out since 1960 in the coastal zone between the Ebro and Castellon (western Mediterranean), data has been collected which confirms the importance of ciliates in the composition and activity of the plankton. The ciliates in 413 samples of 100 ml of water were counted, having been examined with the Utermohl microscope after sedimentation. The samples studied were distributed according to the density of their population. subject for study. The author concludes that recognition of the role of ciliates as an important link in the food chain of the sea would simplify the interpretation of certain problems posed by the nutrition of certain groups of planktonic animals.

Mechanistic studies of a model reaction for enzymatic hydroxylation

<p>A study has been made of the reaction mechanism of a model system for enzymatic hydroxylation. The results of a kinetic study of the hydroxylation of 2-hydroxyazobenzene derivatives by cupric ion and hydrogen peroxide are presented. An investigation of kinetic orders indicates that hydroxylation proceeds by way of a coordinated intermediate complex consisting of cupric ion and the mono anions of 2-hydroxyazobenzene and hydrogen peroxide. Studies with deuterated substrate showed the absence of a primary kinetic isotope effect and no evidence of an NIH shift. The effect of substituents on the formation of intermediate complexes and the overall rate of hydroxylation was studied quantitatively in aqueous solution. The combined results indicate that the hydroxylation step is only slightly influenced by ring substitution. The substituent effect is interpreted in terms of reaction by a radical path or a concerted mechanism in which the formation of ionic intermediates is avoided. The reaction mechanism is discussed as a model for enzymatic hydroxylation. </p>

An investigation of the three-body reaction He^3(He^3, 2p)He^4

<p>Reactions produced by the He³ bombardment of the He³ have been investigated for bombarding energies from 1 to 20 MeV using a tandem Van de Graaff accelerator. Proton spectra from the three-body reaction He³(He³, 2p)He⁴ have been measured with a counter telescope at 13 angles for 9 bombarding energies between 3 and 18 MeV. The results are compared with a model for the reaction which includes a strong p-He⁴ final-state interaction. Alpha-particle spectra have been obtained at 12 and 18 MeV for forward angles with a magnetic spectrometer. These spectra indicate a strongly forward-peaked mechanism involving the ¹S₀ p-p interaction in addition to the p-He⁴ interaction. Measurements of p-He⁴ and p-p coincidence spectra at 10 MeV confirm these features of the reaction mechanism. Deuteron spectra from the reaction of He³(He³, d)pHe³ have been measured at 18 MeV. A triton spectrum from the reaction He³(He³, t)3p at 20 MeV and 4⁰ is interpreted in terms of a sequential decay through an excited state of the alpha particle at 20.0 MeV. No effects are observed which would indicate an interaction in the residual (3p) system. Below 3 MeV the He³(He³, 2p)He⁴ reaction mechanism is observed to be changing and further measurements are suggested in view of the importance of this reaction in stellar interiors. </p>

Depth-sensitive analysis of fluorine on lunar sample surfaces and in carbonaceous chondrites by a nuclear resonant reaction technique

The nuclear resonant reaction ¹⁹F(��,����)¹⁶O has been used to perform depth-sensitive analyses of fluorine in lunar samples and carbonaceous chondrites. The resonance at 0.83 MeV (center-of-mass) in this reaction is utilized to study fluorine surface films, with particular interest paid to the outer micron of Apollo 15 green glass, Apollo 17 orange glass, and lunar vesicular basalts. These results are distinguished from terrestrial contamination, and are discussed in terms of a volcanic origin for the samples of interest. Measurements of fluorine in carbonaceous chondrites are used to better define the solar system fluorine abundance. A technique for measurement of carbon on solid surfaces with applications to direct quantitative analysis of implanted solar wind carbon in lunar samples is described.

Physiological aspects of the life cycle of the river lamprey, Lampetra fluviatilis L

The life cycle of the river lamprey, L. fluviatilis, is reviewed. The larval lamprey, or ammocoete, is a blind, filter-feeding animal, which normally lies concealed in the silt deposits of streams and rivers. After a period of 3-5 years in fresh water the ammocoete undergoes a metamorphosis in the summer months into a sexually immature, non-feeding stage known as the macrophthalia, which is active. This stage migrates downstream in late winter. It adopts a parasitic existence, in intertidal areas. After 18 months it returns to spawn in fresh water, after a final freshwater stage lasting up to 9 months. The river lamprey dies within a few days after the spawning period of 3-4 weeks, and none survive to spawn the following year.

Part I. Coenzyme B12 as a hydroformylation-type catalyst. Part II. Mechanisms of hydrogen transfer in the methylmalonyl coenzyme a mutase reaction

<p>Part I</p> <p>The mechanism of the hydroformylation reaction was studied. Using cobalt deuterotetracarbonyl and 1-pentene as substrates, the first step in the reaction, addition of cobalt tetracarbonyl to an olefin, was shown to be reversible.</p> <p>Part II</p> <p>The role of coenzyme B₁₂ in the isomerization of methylmalonyl coenzyme A to succinyl coenzyme A by methylmalonyl coenzyme A mutase was studied. The reaction was allowed to proceed to partial completion using a mixture of methylmalonyl coenzyme A and 4, 4, 4-tri-²H-methylmalonyl coenzyme A as substrate. The deuterium distribution in the product, succinyl coenzyme A, was shown to best fit a model in which hydrogen is transferred from C-4 of methylmalonyl coenzyme A to C-5��� of the adenosyl moiety of coenzyme B₁₂ in the rate determining step. The three hydrogens at the 5���-adenosyl position of the coenzyme B₁₂ intermediate are then able to become enzymatically equivalent before hydrogen is transferred from the coenzyme B₁₂ intermediate to form succinyl coenzyme A.</p>

Part I. Synchronization of the cell division cycle of HeLa cells in suspension cultures. Part II. Studies on chromosomal proteins of HeLa cells during the cell division cycle

<p>Part I</p> <p>These studies investigate the potential of single and double treatments with either 5-fluorodeoxyuridine of excess thymidine to induce cell division synchrony in suspension cultures of HeLa cells. The patterns of nucleic acid synthesis and cell proliferation have been analyzed in cultures thus synchronized. Several changes in cell population during long incubation with 5-fluorodeoxyuridine or excess thymidine are also described. These results are subjected to detailed evaluation in terms of the degree and quality of synchrony finally achieved.</p> <p>Part II</p> <p>Histones and non-histone proteins associated with interphase and metaphase chromosomes of HeLa cells have been qualitatively and quantitatively analyzed. Histones were fractionated by chromatography on Amberlite CG-50 and further characterized by analytical disc electrophoresis and amino acid analysis of each chromatographic fraction. It is concluded that histones of HeLa cells are comprised of only a small number of major components and that these components are homologous to those of other higher organisms. Of all the histones, arginine-rich histone III alone contains cysteine and can polymerize through formation of intermolecular disulfide bridges between histone III monomers. </p> <p>A detailed comparison by chromatography and disc electrophoresis established that interphase and metaphase histones are made up of similar components. However, certain quantitative differences in proportions of different histones of interphase and metaphase cells are reported. Indirect evidence indicates that a certain proportion of metaphase histone III is polymerized through intermolecular disulfide links, whereas interphase histone III occurs mainly in the monomeric form. </p> <p>Metaphase chromosomes are associated with an additional acid-soluble protein fraction which is absent from interphase chromosomes. All of these additional acid-soluble proteins of metaphase chromosomes are shown to be non-histones and it is concluded that the histone/DNA ratio is identical in interphase and metaphase chromosomes. The bulk of acid-soluble non-histone proteins of metaphase chromosomes were found to be polymerized through disulfide bridges; corresponding interphase non-histone proteins displayed no evidence of similar polymerization. </p> <p>The factors responsible for the condensed configuration and metabolic inactivity of metaphase chromosomes are discussed in light of these findings. </p> <p>The relationship between histone and DNA synthesis in nondividing differentiated chicken erythrocyte cells and in rapidly dividing undifferentiated HeLa cells is also investigated. Of all the histones, only arginine-rich histones are synthesized in mature erythrocytes. Histone synthesis in HeLa cells was studied in both unsynchronized and synchronized cultures. In HeLa cells, only part of the synthesis of all histone fractions is dependent on concurrent DNA synthesis, whereas all histones are synthesized in varying degrees even in the absence of DNA synthesis. </p>

Stationary Eddies and Zonal Variations of the Global Hydrological Cycle in a Changing Climate

<p>This thesis advances our physical understanding of the sensitivity of the hydrological cycle to global warming. Specifically, it focuses on changes in the longitudinal (zonal) variation of precipitation minus evaporation (P - E), which is predominantly controlled by planetary-scale stationary eddies. By studying idealized general circulation model (GCM) experiments with zonally varying boundary conditions, this thesis examines the mechanisms controlling the strength of stationary-eddy circulations and their role in the hydrological cycle. The overarching goal of this research is to understand the cause of changes in regional P - E with global warming. An understanding of such changes can be useful for impact studies focusing on water availability, ecosystem management, and flood risk.</p> <p>Based on a moisture-budget analysis of ERA-Interim data, we establish an approximation for zonally anomalous P - E in terms of surface moisture content and stationary-eddy vertical motion in the lower troposphere. Part of the success of this approximation comes from our finding that transient-eddy moisture fluxes partially cancel the effect of stationary-eddy moisture advection, allowing divergent circulations to dominate the moisture budget. The lower-tropospheric vertical motion is related to horizontal motion in stationary eddies by Sverdrup and Ekman balance. These moisture- and vorticity-budget balances also hold in idealized and comprehensive GCM simulations across a range of climates.</p> <p>By examining climate changes in the idealized and comprehensive GCM simulations, we are able to show the utility of the vertical motion P - E approximation for splitting changes in zonally anomalous P - E into thermodynamic and dynamic components. Shifts in divergent stationary-eddy circulations dominate changes in zonally anomalous P - E. This limits the local utility of the "wet gets wetter, dry gets drier��� idea, where existing P - E patterns are amplified with warming by the increase in atmospheric moisture content, with atmospheric circulations held fixed. The increase in atmospheric moisture content manifests instead in an increase in the amplitude of the zonally anomalous hydrological cycle as measured by the zonal variance of P - E. However, dynamic changes, particularly the slowdown of divergent stationary-eddy circulations, limit the strengthening of the zonally anomalous hydrological cycle. In certain idealized cases, dynamic changes are even strong enough to reverse the tendency towards "wet gets wetter, dry gets drier��� with warming.</p> <p>Motivated by the importance of stationary-eddy vertical velocities in the moisture budget analysis, we examine controls on the amplitude of stationary eddies across a wide range of climates in an idealized GCM with simple topographic and ocean-heating zonal asymmetries. An analysis of the thermodynamic equation in the vicinity of topographic forcing reveals the importance of on-slope surface winds, the midlatitude isentropic slope, and latent heating in setting the amplitude of stationary waves. The response of stationary eddies to climate change is determined primarily by the strength of zonal surface winds hitting the mountain. The sensitivity of stationary-eddies to this surface forcing increases with climate change as the slope of midlatitude isentropes decreases. However, latent heating also plays an important role in damping the stationary-eddy response, and this damping becomes stronger with warming as the atmospheric moisture content increases. We find that the response of tropical overturning circulations forced by ocean heat-flux convergence is described by changes in the vertical structure of moist static energy and deep convection. This is used to derive simple scalings for the Walker circulation strength that capture the monotonic decrease with warming found in our idealized simulations.</p> <p>Through the work of this thesis, the advances made in understanding the amplitude of stationary-waves in a changing climate can be directly applied to better understand and predict changes in the zonally anomalous hydrological cycle.</p>

An investigation of the reaction negative K��p ��� K������� at P_(lab) = 2 Gev/c

<p>The reaction K^-p���K^-��⁺n has been studied for incident kaon momenta of 2.0 GeV/c. A sample of 19,881 events was obtained by a measurement of film taken as part of the K-63 experiment in the Berkeley 72 inch bubble chamber. </p> <p>Based upon our analysis, we have reached four conclusions. (1) The magnitude of the extrapolated K�� cross section differs by a factor of 2 from the P-wave unitarity prediction and the K⁺n results; this is probably due to absorptive effects. (2) Fits to the moments yield precise values for the K�� S-wave which agree with other recent statistically accurate experiments. (3) An anomalous peak is present in our backward K^-p���(��+n) K^- u-distribution. (4) We find a non-linear enhancement due to interference similiar to the one found by Bland et al. (Bland 1966).</p>

Part I: Total yield measurements for the ^(21)Ne(��,n)^)(24)Mg reaction. Part II: A study of the ^(12)C(He,p)^(14)N reaction

<p>PART I</p> <p>The total cross-section for the reaction ²¹Ne(��, n)²⁴Mg has been measured in the energy range 1.49 Mev ��� E_cm ��� 2.6 Mev. The cross-section factor, S(O), for this reaction has been determined, by means of an optical model calculation, to be in the range 1.52 x 10¹² mb-Mev to 2.67 x 10¹² mb-Mev, for interaction radii in the range 5.0 fm to 6.6 fm. With S(O) ��� 2 x 10¹² mb-Mev, the reaction ²¹Ne(��, n)²⁴Mg can produce a large enough neutron flux to be a significant astrophysical source of neutrons.</p> <p>PART II</p> <p>The reaction¹²C(³He, p)¹⁴N has been studied over the energy range 12 Mev ��� E_lab ��� 18 Mev. Angular distributions of the proton groups leading to the lowest seven levels in ¹⁴N were obtained.</p> <p>Distorted wave calculations, based on two-nucleon transfer theory, were performed, and were found to be reliable for obtaining the value of the orbital angular momentum transferred. The present work shows that such calculations do not yield unambiguous values for the spectroscopic factors.</p>

Alterations of the global water cycle and their effects on river structure, function and services

River structure and functioning are governed naturally by geography and climate but are vulnerable to natural and human-related disturbances, ranging from channel engineering to pollution and biological invasions. Biological communities in river ecosystems are able to respond to disturbances faster than those in most other aquatic systems. However, some extremely strong or lasting disturbances constrain the responses of river organisms and jeopardise their extraordinary resilience. Among these, the artificial alteration of river drainage structure and the intense use of water resources by humans may irreversibly influence these systems. The increased canalisation and damming of river courses interferes with sediment transport, alters biogeochemical cycles and leads to a decrease in biodiversity, both at local and global scales. Furthermore, water abstraction can especially affect the functioning of arid and semi-arid rivers. In particular, interception and assimilation of inorganic nutrients can be detrimental under hydrologically abnormal conditions. Among other effects, abstraction and increased nutrient loading might cause a shift from heterotrophy to autotrophy, through direct effects on primary producers and indirect effects through food webs, even in low-light river systems. The simultaneous desires to conserve and to provide ecosystem services present several challenges, both in research and management.