A theory on the migration of an extraneous electron across hydrogen bonds in polypeptides

The migrating electrons in biological systems normally are extraneous and taking this into account the electron delocalisation across the hydrogen bonds in proteins is re-examined. It is seen that an extraneous electron can travel rapidly via the low-lying virtual orbitals of the hydrogen-bonded π-electronic structure of peptide units in proteins. The frequency of electron transfer decreases slowly with an increase in the path length. However, the coupling of electron and protonic motions enhances this frequency. Transfer of electrons across the hydrogen bonds in accordance with the double-exchange mechanism does not appear to be possible. This theory offers a possibility for an extraneous electron to transfer within protein structures.

Puhetavat naisten asemasta ja sukupuolten tasa-arvosta Kamerunissa: diskursiivinen näkökulma kamerunilaisilla asiantuntijoilla kerättyyn haastatteluaineistoon kriittis-feministisen viitekehyksen valossa

Tässä sosiaalipsykologian pro gradu -tutkielmassa tarkastellaan naisten asemaan ja sukupuolten väliseen tasa- arvoon liittyviä puhetapoja kamerunilaisilla tasa-arvokysymysten asiantuntijoilla. Asiantuntijat edustavat erilaisia paikallisia naisten oikeuksia ja sukupuolten tasa-arvoa edistäviä kansalaisjärjestöjä ja yhdistyksiä. Sukupuolten välisen tasa-arvon kehittäminen ja naisen aseman parantaminen globaalisti ovat olleet viime aikoina pinnalla. Tasa-arvon edistäminen on ollut myös afrikkalaisten yhteiskuntien haasteita jälki-kolonialistisella ajalla. Tässä tutkimuksessa ollaan kiinnostuneita mahdollisista ristiriidoista ja jännitteistä, joita syntyy länsimaisten ja paikallisten tasa-arvokäsitysten kohdatessa. Aineistona on sosiaalipsykologian laitoksen tutkimusprojektin yhteydessä Kamerunissa vuonna 2001 naisten asioita ajavien järjestöjen työntekijöillä kerätty haastatteluaineisto, jota lähestytään kielenkäytön sosiaalista todellisuutta rakentavaa luonnetta painottavasta diskursiivisesta näkökulmasta. Metodisesti tutkimuksessa nojaudutaan diskursiivisen sosiaalipsykologian, erityisesti brittiläisen diskursiivisen psykologian ja suomalaisen diskurssianalyysin, epistemologisiin lähtökohtiin ja teoreettis-metodologiseen välineistöön. Tärkeimmät analyyttiset käsitteet ovat tulkintarepertuaari ja subjektipositio. Aineistosta etsittiin puhetapoja mm. paikantamalla retorisia keinoja, joilla erilaisia kantoja faktuaalistetaan. Haastatteluaineistoa lähestytään sosiaalista todellisuutta tuottavana tilanteisena toimintana. Tutkimuksessa keskitytään analysoimaan sitä, miten sekä haastattelija että haastateltavat tarjoavat, haastavat ja tuottavat erilaisia kantoja siitä, mikä naisten asema Kamerunissa on ja miten sitä tulisi parantaa. Lisäksi tarkastellaan sitä, millaisena länsimainen näkökulma naisten asemaan ilmenee haastateltavien puheessa. Tutkimustuloksina löydettiin kaksi laajempaa puhetapaa, joiden alle tulkintarepertuaarit lukeutuivat. Nämä nimettiin ”tasa-arvopuheeksi” ja ”kulttuurieropuheeksi”. Tasa-arvopuheessa tasa-arvo ja naisten aseman parantaminen esitettiin tavoiteltavana päämääränä, ja siinä tuotettiin sosiaalista todellisuutta, jossa naisten asema esitettiin epätasa-arvoisena ja sukupuolten väliset suhteet nähtiin hierarkkisina ja alistavina naisten kannalta. Tämä puhetapa liittyi ensisijaisesti järjestön tehtävään, ja se tulkittiin keinoksi oikeuttaa järjestön toimintaa tasa-arvon edistämiseksi. Tämän puhetavan alla erottui kaksi tulkintarepertuaaria: ”tietämättömyys tasa-arvon esteenä” ja ”uskomukset tasa-arvon esteenä”. Kulttuurieropuheessa haastateltavat rakensivat eroa länsimaisen/eurooppalaisen ja afrikkalaisen/kamerunilaisen kulttuurin välille. Toisaalta länsimainen feminismi tarjosi haastateltaville keinoja samaistua ”yhteiseen taisteluun” naisten oikeuksien puolesta. Toisaalta länsimainen feminismi edusti haastateltaville ei-tavoiteltavaa tilaa, joka näyttäytyi peruuttamattomasti yhteen sovittamattomalta afrikkalaisen naiskuvan kanssa. Kulttuurieropuheen alle hahmottui kaksi erilaista puhetapaa, jotka nimettiin ”tasa-arvo naisten taisteluna” tulkintarepertuaariksi ja ”afrikkalaisen naisen” tulkintarepertuaariksi. Tärkeimpiä lähteitä metodin osalta olivat Potter & Wetherell (1987), Edwards & Potter (1992) sekä Jokinen, Juhila & Suoninen (1993, 1999). Teoreettisessa viitekehyksessä nojauduttiin tasa-arvon teoretisoinnin osalta mm. Anne Maria Hollin (1996, 2003) ja postkoloniaalin feminismin viitekehyksen osalta mm. Chandra Mohantyn (1984, 2003) kirjoituksiin.

Nonlinear fracture properties of concrete-concrete interfaces

The fracture properties of different concrete-concrete interfaces are determined using the Bazant's size effect model. The size effect on fracture properties are analyzed using the boundary effect model proposed by Wittmann and his co-workers. The interface properties at micro-level are analyzed through depth sensing micro-indentation and scanning electron microscopy. Geometrically similar beam specimens of different sizes having a transverse interface between two different strengths of concrete are tested under three-point bending in a closed loop servo-controlled machine with crack mouth opening displacement control. The fracture properties such as, fracture energy (G(f)), length of process zone (c(f)), brittleness number (beta), critical mode I stress intensity factor (K-ic), critical crack tip opening displacement CTODc (delta(c)), transitional ligament length to free boundary (a(j)), crack growth resistance curve and micro-hardness are determined. It is seen that the above fracture properties decrease as the difference between the compressive strength of concrete on either side of the interface increases. (C) 2010 Elsevier Ltd. All rights reserved.

How do heterogametic females survive without gene dosage compensation?

When the male is the heterogametic sex (XX♀-XY♂ or XX♀-XO♂), as inDrosophila, orthopteran insects, mammals andCaenorhabditis elegans, X-linked genes are subject to dosage compensation: the single X in the male is functionally equivalent to the two Xs in the female. However, when the female is heterogametic (ZZ♂-ZW♀), as in birds, butterflies and moths, Z-linked genes are apparently not dosage-compensated. This difference between X-linked and Z-linked genes raises fundamental questions about the role of dosage compensation. It is argued that (i) genes which require dosage compensation are primarily those that control morphogenesis and the prospective body plan; (ii) the products of these genes are required in disomic doses especially during oogenesis and early embryonic development; (iii) heterogametic females synthesize and store during oogenesis itself morphogenetically essential gene products - including those encoded by Z-linked genes — in large quantities; (iv) the abundance of these gene products in the egg and their persistence relatively late into embryogenesis enables heterogametic females to overcome the monosomic state of the Z chromosome in ZW embryos. Female heterogamety is predominant in birds, reptiles and amphibians, all of which have megalecithal eggs containing several thousand times more maternal RNA and other maternal messages than eggs of mammals,Caenorhabditis elegans, orDrosophila. This increase in egg size, yolk content and, concomitantly, the size of the maternal legacy to the embryo, may have facilitated female heterogamety and the absence of dosage compensation.

Inertial effects in solvation dynamics

The dynamics of solvation of newly created charged species in dense dipolar liquids can proceed at a high speed with time constants often in the subpicosecond domain. The motion of the solvent molecules can be in the inertial limit at such short times. In this paper we present a microscopic study of the effects of inertial motion of solvent molecules on the solvation dynamics of a newly created ion in a model dipolar liquid. Interesting dynamical behavior emerges when the relative contribution of the translational modes in the wave-vector-dependent longitudinal relaxation time is significant. Especially, the theory predicts that the time correlation function of the solvation energy can become oscillatory in some limiting situations. In general, the dynamics becomes faster in the presence of the inertial contribution. We discuss the experimental situations where the inertial effects can be noticeable.

Molecular theory of dielectric relaxation in a dense binary dipolar liquid

A molecular theory of dielectric relaxation in a dense binary dipolar liquid is presented. The theory takes into account the effects of intra- and interspecies intermolecular interactions. It is shown that the relaxation is, in general, nonexponential. In certain limits, we recover the biexponential form traditionally used to analyze the experimental data of dielectric relaxation in a binary mixture. However, the relaxation times are widely different from the prediction of the noninteracting rotational diffusion model of Debye for a binary system. Detailed numerical evaluation of the frequency-dependent dielectric function epsilon-(omega) is carried out by using the known analytic solution of the mean spherical approximation (MSA) model for the two-particle direct correlation function for a polar mixture. A microscopic expression for both wave vector (k) and frequency (omega) dependent dielectric function, epsilon-(k,omega), of a binary mixture is also presented. The theoretical predictions on epsilon-(omega) (= epsilon-(k = 0, omega)) have been compared with the available experimental results. In particular, the present theory offers a molecular explanation of the phenomenon of fusing of the two relaxation channels of the neat liquids, observed by Schallamach many years ago.

The short range interactions between two rare gas atoms

The short range interactions in He2, Ne2 and Ar2 have been studied in terms of the electronic forces as functions of their internuclear separations employing their single configuration SCF wave functions. The results show that the constituent molecular orbitals behave differently in terms of the forces they exert on the nuclei during the interaction process. The different behaviour of the orbitals is also reflected in the redistribution of charges.

Relaxation dominated by inertia: Solvation dynamics of a small ion in a dipolar solvent

It is shown from an analytical theory that the solvation dynamics of a small ion can be controlled largely by the inertial response of the dipolar solvent when the liquid is in the underdamped limit. It is also shown that this inertial response arises primarily from the long wavelength (with wavevector k≃0) processes which have a collective excitation-like behaviour. The long time decay is dominated by the processes occurring at molecular lengthscales. The theoretical results are in good agreement with recent computer simulation results.

Role of barriers to conformational changes in ketones undergoing the Norrish type II process

The Norrish type II process is examined in three ketones containing primary, secondary and tertiary C---H bonds in the γ position relative to the carbonyl groups; the MINDO/3 semiempirical self-consistent field (SCF) molecular orbital (MO) method was used with complete geometry optimization in the unrestricted Hartree—Fock frame for the open-shell species. Results show that barriers to conformational change in ketones play an important role in the triplet reaction.

Synthesis Of (+/-)-2-Isopropyl-5,6-Dimethylbicyclo[3.2.1]Oct-6-En-8-One

Methanolic hydrogen chloride cyclization of the triketone 8, prepared from the Mannich base 7 and 2-methylcyclopentane-1,3-dione, gives ketones 9 and 10. NaBH4 reduction of 9 followed by Grignard reaction with CH3MgI affords the diol 12. Catalytic hydrogenation of 12 followed by PCC oxidation yields the ketoalcohol 13. Dehydration of 13 with SOCl2/pyridine results in a 1:1 mixture of the endo-14 and exo-15 olefins, separated by chromatography.

Nucleosome core histone complex isolated gently and rapidly in 2 M NaCl is octameric

A relatively stable specific complex of the chromatin core histones H2A, H2B, H3, and H4 has been obtained in 2 M NaCl/25 mM sodium phosphate buffer, pH 7.0. The histone core complex has an apparent specific volume of 0.73 ml/g. Its sedimentation coefficient was dependent on rotor speed (angular velocity, omega) and attained different stable values at low and high rotor speeds. The drop in sedimentation coefficient occurred sharply between omega 2 values of about 9 x 10(6) and 1.1 x 10(7) (radians/sec)2. The s020,w corresponding to zero angular velocity (1 atmosphere pressure) was 6.6 S +/- (SEM) 0.1 S. At high rotor speeds the value decreased to 3.8 S +/- 0.1 S. The core complex has a diffusion coefficient, D20,w, of 5.4 x 10(-7) cm2/sec and a molecular weight of 108,000 +/- (SD) 2500.