Static and dynamic characteristics of cerebral blood flow during the resting state in schizophrenia

Background: The cerebral network that is active during rest and is deactivated during goal-oriented activity is called the default mode network (DMN). It appears to be involved in self-referential mental activity. Atypical functional connectivity in the DMN has been observed in schizophrenia. One hypothesis suggests that pathologically increased DMN connectivity in schizophrenia is linked with a main symptom of psychosis, namely, misattribution of thoughts. Methods: A resting-state pseudocontinuous arterial spin labeling (ASL) study was conducted to measure absolute cerebral blood flow (CBF) in 34 schizophrenia patients and 27 healthy controls. Using independent component analysis (ICA), the DMN was extracted from ASL data. Mean CBF and DMN connectivity were compared between groups using a 2-sample t test. Results: Schizophrenia patients showed decreased mean CBF in the frontal and temporal regions (P < .001). ICA demonstrated significantly increased DMN connectivity in the precuneus (x/y/z = -16/-64/38) in patients than in controls (P < .001). CBF was not elevated in the respective regions. DMN connectivity in the precuneus was significantly correlated with the Positive and Negative Syndrome Scale scores (P < .01). Conclusions: In schizophrenia patients, the posterior hub-which is considered the strongest part of the DMN-showed increased DMN connectivity. We hypothesize that this increase hinders the deactivation of the DMN and, thus, the translation of cognitive processes from an internal to an external focus. This might explain symptoms related to defective self-monitoring, such as auditory verbal hallucinations or ego disturbances.

The triplite–triploidite supergroup: structural modulation in wagnerite, discreditation of magniotriplite, and the new mineral hydroxylwagnerite

Electron-microprobe analysis, single-crystal X-ray diffraction with an area detector, and high-resolution transmission electron microscopy show that minerals related to wagnerite, triplite and triploidite, which are monoclinic Mg, Fe and Mn phosphates with the formula Me2+ 2PO4(F,OH), constitute a modulated series based on the average triplite structure. Modulation occurs along b and may be commensurate with (2b periodicity) or incommensurate but generally close to integer values (∼3b, ∼5b, ∼7b, ∼9b), i.e. close to polytypic behaviour. As a result, the Mg- and F-dominant minerals magniotriplite and wagnerite can no longer be considered polymorphs of Mg2PO4F, i.e., there is no basis for recognizing them as distinct species. Given that wagnerite has priority (1821 vs. 1951), the name magniotriplite should be discarded in favour of wagnerite. Hydroxylwagnerite, end-member Mg2PO4OH, occurs in pyrope megablasts along with talc, clinochlore, kyanite, rutile and secondary apatite in two samples from lenses of pyrope–kyanite–phengite–quartz-schist within metagranite in the coesite-bearing ultrahigh-pressure metamorphic unit of the Dora-Maira Massif, western Alps, Vallone di Gilba, Val Varaita, Piemonte, Italy. Electron microprobe analyses of holotype hydroxylwagnerite and of the crystal with the lowest F content gave in wt%: P2O5 44.14, 43.99; SiO2 0.28, 0.02; SO3 –, 0.01; TiO2 0.20, 0.16; Al2O3 0.06, 0.03; MgO 48.82, 49.12; FeO 0.33, 0.48; MnO 0.01, 0.02; CaO 0.12, 0.10; Na2O 0.01, –; F 5.58, 4.67; H2O (calc) 2.94, 3.36; –O = F 2.35, 1.97; Sum 100.14, 99.98, corresponding to (Mg1.954Fe0.007Ca0.003Ti0.004Al0.002Na0.001)Σ=1.971(P1.003Si0.008)Σ=1.011O4(OH0.526F0.474)Σ=1 and (Mg1.971Fe0.011Ca0.003Ti0.003Al0.001)Σ=1.989(P1.002Si0.001)Σ=1.003O4(OH0.603F0.397)Σ=1, respectively. Due to the paucity of material, H2O could not be measured, so OH was calculated from the deficit in F assuming stoichiometry, i.e., by assuming F + OH = 1 per formula unit. Holotype hydroxylwagnerite is optically biaxial (+), α 1.584(1), β 1.586(1), γ 1.587(1) (589 nm); 2V Z(meas.) = 43(2)°; orientation Y = b. Single-crystal X-ray diffraction gives monoclinic symmetry, space group P21/c, a = 9.646(3) Å, b = 12.7314(16) Å, c = 11.980(4) Å, β = 108.38(4) , V = 1396.2(8) Å3, Z = 16, i.e., hydroxylwagnerite is the OH-dominant analogue of wagnerite [β-Mg2PO4(OH)] and a high-pressure polymorph of althausite, holtedahlite, and α- and ε-Mg2PO4(OH). We suggest that the group of minerals related to wagnerite, triplite and triploidite constitutes a triplite–triploidite super-group that can be divided into F-dominant phosphates (triplite group), OH-dominant phosphates (triploidite group), O-dominant phosphates (staněkite group) and an OH-dominant arsenate (sarkinite). The distinction among the three groups and a potential fourth group is based only on chemical features, i.e., occupancy of anion or cation sites. The structures of these minerals are all based on the average triplite structure, with a modulation controlled by the ratio of Mg, Fe2+, Fe3+ and Mn2+ ionic radii to (O,OH,F) ionic radii.

A study protocol of a randomised controlled trial to measure the effects of an augmented prescribed exercise programme (APEP) for frail older medical patients in the acute setting

Background: Older adults experience functional decline in hospital leading to increased healthcare burden and morbidity. The benefits of augmented exercise in hospital remain uncertain. The aim of this trial is to measure the short and longer-term effects of augmented exercise for older medical in-patients on their physical performance, quality of life and health care utilisation. Design and Methods: Two hundred and twenty older medical patients will be blindly randomly allocated to the intervention or sham groups. Both groups will receive usual care (including routine physiotherapy care) augmented by two daily exercise sessions. The sham group will receive stretching and relaxation exercises while the intervention group will receive tailored strengthening and balance exercises. Differences between groups will be measured at baseline, discharge, and three months. The primary outcome measure will be length of stay. The secondary outcome measures will be healthcare utilisation, activity (accelerometry), physical performance (Short Physical Performance Battery), falls history in hospital and quality of life (EQ-5D-5 L). Discussion: This simple intervention has the potential to transform the outcomes of the older patient in the acute setting.

Prática de ensino supervisionada em educação pré-escolar e ensino do 1º ciclo do ensino básico: tornando-se educadora/professora

O presente relatório da Prática de Ensino Supervisionada (PES) resulta da observação e participação no contexto da PES em Educação Pré-Escolar realizado em Florianópolis, Santa Catarina (Brasil), através do programa Luso-Brasileiro, no Núcleo de Educação Infantil Colónia Z-11 e da PES em 1º Ciclo do Ensino Básico na Escola EB1 da Quinta da Vista Alegre, pertencente ao Agrupamento Manuel Ferreira Patrício de Évora. O relatório centra-se no meu percurso e aprendizagens como futura educadora/professora: ir aprendendo a profissão em contexto, indo ao encontro de quem somos e em quem nos vamos tornando, dando enfase ao papel das crianças nos processos de aprendizagem que experimentámos. Na conceção da ação educativa, tornada prática pedagógica em contexto, a avaliação, formativa e transformadora, assim como a reflexão acerca da prática foram fundamentais para o melhoramento da intervenção e, por tal, influências positivas na aprendizagem das crianças e na minha aprendizagem profissional. A problemática deste relatório teve como base o querer compreender relações entre uma reflexão sistemática, por escrito, sobre o desenvolvimento do meu projeto de formação em contexto, considerando que a avaliação formativa deveria nortear e monitorizar o nosso trabalho, as relações e aprendizagens, na ação docente que ia desenvolvendo, quer em Educação Pré-Escolar quer no 1º Ciclo. Neste percurso, entrelaçando a ação e a investigação, procurei respostas para as seguintes questões: o que sabia acerca da docência que se pauta por uma avaliação formativa e formadora no trabalho com crianças? O que fiz para aprendermos em conjunto, tendo em conta uma função reguladora que a avaliação poderia tomar? Como o fiz? Em que momentos e com quem? Para quê, com que finalidade? O que aprendi no decorrer deste processo de aprendizagem profissional, onde a investigação-ação teve um papel relevante?; Supervised Teaching Practice’s Report to obtain a Master’s Degree in Preschool and Primary school: Abstract: The present report of Supervised Teaching Practice (STP) is a result of the observation and participation in context of STP in pre-school that took place in Florianópolis, Santa Catarina (Brazil), through the Luso-Brazilian program, in Núcleo de Educação Infantil Colónia Z-11 and through STP in Primary School of Ensino Básico in Escola EB1 da Quinta da Vista Alegre, which belongs to the Manuel Ferreira de Évora Group. The report focuses on my journey and learnings as a future teacher: learning the profession in it’s actual context, trying to find who we are and what we can become, and emphasizing the children’s role in these learning processes. In the conception of the education activities, which became possible by pedagogical practice in context, the evaluation, formative and transformative, as well as the reflection about the practice were vital to improve the intervention and, consequently, to have a positive influence in the children’s learning process and in my own professional experience. The main focus of this report is to understand the relation between a systematic reflection, in writing, about the development of my teaching in context project, considering that the formative evaluation should guide and monitor our work, the relationships and learnings, in the educational process that I developed, either in pre-school or primary school. In this journey, by combining action and investigation, the main intention was to answer the following questions: What did I know about teaching characterized by a formative assessment when working with children? What did I do so we could learn together, bearing in mind a regulative function that evaluation could take? How did I do it? In what moments and whom with? What for, and what was the purpose? What did I learn throughout this professional learning process, where the investigation-action played a major role?

Prática de ensino supervisionada em educação pré-escolar e ensino do 1.º ciclo do ensino básico. Cidadania na infância: contributos para uma educação na e para a cidadania

O presente relatório da Prática de Ensino Supervisionada em Educação Pré-escolar e Ensino do 1.º ciclo do Ensino Básico pretende dar a conhecer os aspetos inerentes à dimensão investigativa que desenvolvi na instituição Núcleo de Educação Infantil Colônia Z-11, no Brasil, na cidade de Florianópolis, no ano letivo de 2015; e na instituição Escola Básica dos Canaviais, em Portugal, na cidade de Évora, no ano letivo de 2015/2016. Este relatório incide na temática Cidadania na Infância. Tive como propósito legitimar a criança como sujeito social (a criança cidadã) e contribuir para uma educação que vise a cidadania como direito na infância. Foi deste modo que me propus compreender como poderia contribuir nos espaços institucionais para uma educação na cidadania, vivida no presente, e uma educação para a cidadania, projetada para uma integração do cidadão também no futuro. Considerei que as instituições educativas devem criar uma relação com o dia-a-dia da criança nas diversas áreas, disciplinares e não disciplinares. Numa perspetiva de cidadania participativa, valorizando as instituições educativas como espaços de aquisição e de desenvolvimento de atitudes e competências do cidadão. A dimensão investigativa que desenvolvi no contexto de pré-escolar pretendeu acentuar a consciência de uma identidade cultural, coletiva e individual, valorizando os saberes que as crianças trazem do meio sociocultural de origem. A dimensão investigativa que desenvolvi no contexto de 1.ºciclo pretendeu promover espaços de diálogo, coconstrutivos para as aprendizagens do e entre o grupo. Através de uma análise reflexiva dos instrumentos de recolha de dados tentei dar resposta às questões que orientaram a investigação-ação que realizei, sendo estas: [O que é que a cidadania pode significar nos contextos educativos?]; [Como se promove a cidadania nas instituições escolares?] e [Como criar ambientes que permitam a participação cívica de todos?]; Report of the Supervised Teaching Practice to achieve the Master’s Degree in Pre-school Education and Teaching of the Primary School Abstract: The present report of Supervised Teaching Practice in Preschool Education and in Primary School aims to present the aspects inherent to the research dimension that I developed at the Núcleo de Educação Infantil Colônia Z-11, in Brazil, in the City of Florianopolis, in the academic year of 2015; And at the institution Escola Básica dos Canaviais, in Portugal, in the city of Évora, in the academic year of 2015/2016. The report focuses on the theme of Citizenship in childhood. I had the purpose to legitimize the child as a social subject (the child citizen) and contribute to an education that aims at citizenship as a right in childhood. It was in this way that I set out to understand how I could contribute in the institutional spaces for an education in citizenship, lived in the present, and an education for citizenship, projected for an integration of the citizen in the future. I considered that educational institutions should create a relationship with the child's daily life in the various areas, disciplinary and non-disciplinary. In a perspective of participatory citizenship, valuing educational institutions as spaces for acquisition and development of citizens' attitudes and skills. The research dimension that I developed in the pre-school context sought to accentuate the awareness of a collective, individual and cultural identity, valuing the knowledge that children bring from the socio-cultural environment where the child was born and lives. The investigative dimension that I developed in the context of the Primary School was intended to promote spaces for dialogue, coconstructives to the learnings of and between the group. Through a reflexive analysis of the instruments of data collection I tried to answer the questions that guide the action research that I realized, being these: [What can citizenship mean in the school contexts?]; [How citizenship could be promoted in the school institutions?] And [How to create environments which allow the civics participation of all?].

Prática de ensino supervisionada em Pré-escolar e em 1.º ciclo do ensino básico: organização de ambientes educativos promotores da educação em ciências naturais

O presente relatório, elaborado no âmbito Prática de Ensino Supervisionada em Pré-Escolar e em 1.º Ciclo do Ensino Básico dá a conhecer os processos de aprendizagem imanentes à prática desenvolvida em contexto. Em Educação Pré- Escolar elaborei um memorial de formação que permitiu refletir sobre as experiências vividas no estágio, possibilitando a aquisição de conhecimentos e aprendizagens profissionais. No 1º Ciclo do Ensino Básico o estágio também assumiu uma perspetiva reflexiva que me permitiu aprender a profissão, mas a dinâmica do trabalho com as crianças possibilitou, igualmente, a realização de um projeto alinhado com a investigação-ação. Os contextos foram diferenciados pela sua especificidade, quer pela situação geográfica e cultural das instituições, quer pelo nível de ensino em que se desenvolveram. A prática educativa em 1º Ciclo do Ensino Básico ocorreu na escola EB/JI Galopim de Carvalho em Évora, já a prática em Pré-Escolar ocorreu no Núcleo de Educação Infantil Colônia Z-11, na cidade de Florianópolis no Brasil. No que respeita à dimensão investigativa, dediquei especial atenção à “Organização de Ambientes Educativos Promotores da Educação em Ciências Naturais”, com vista a compreender como é que aprender ciências pode contribuir para a literacia científica das crianças tendo em vista o exercício de uma cidadania informada. Para tal as crianças envolveram-se ativamente no processo de construção do seu próprio conhecimento. Recorri a autores que me deram contributos para conceber, planear e fundamentar as práticas, quer do ponto de vista pedagógico quer do ponto de vista dos conteúdos curriculares. Para a recolha e tratamento da informação, atendi aos contextos onde o trabalho se realizou, bem como às observações dos diversos intervenientes na supervisão dos estágios, a planificações e reflexões semanais que fui elaborando e me permitiram concretizar uma análise imprescindível para as aprendizagens concretizadas e apresentadas no presente Relatório; REPORT OF SUPERVISED TEACHING PRACTICE IN PRE-SCHOOL EDUCATION AND THE 1ST CYCLE OF PRIMARY EDUCATION: ORGANIZATION OF EDUCATIONAL ENVIRONMENTS PROMOTERS OF EDUCATION IN NATURAL SCIENCES Abstract: The present report, elaborated in the scope of the Practice of Supervised Teaching in Pre-School and in the Primary Education, makes to known the learning processes inherent to the practice developed in context. In Pre-School Education, I created a training memorial that allowed me to reflect on the experiences I had live in the internship, making possible the acquisition of professional’s knowledges and learnings. In Primary School the internship also assumed a reflexive perspective which allowed me to learn the profession, but the dynamic of the work with the children allowed me to, equally, the realization of a project lined up with the action-research. The contexts where differentiated by their specificity, by the institutions geographic location, by the cultural situation and by the learning level where they were developed. The educational practice in Primary School occurred in the school EB/JI Galopim de Carvalho in Évora and the Pre-School practice occurred in Núcleo de Educação Infantil Colônia Z-11, in Brazil in the city of Florianopolis. In the matter of the investigative dimension, I dedicated special attention to the “Organization of Educative Environments Promoters of Natural Sciences Education”, to understand how learning sciences can contribute to scientifically literacy of the children, having in view the exercise of an informed citizenship. For this the children involved actively in the process of building their own knowledge. I resorted to authors who give me contributes to conceive, to plan and to fundament the practices, both from the pedagogical point of view and from the curricular contents point of view. To the collect and treat of data, I attend to the contexts where the work were realized, to the observations of the diverse actors in the internship supervision, to the daily plans and weekly reflections which I had been elaborating and which allowed me to concretize an indispensable analysis to the learnings achieve and presented in the present report.

The persistence of the HgCl2 molecule in five new compounds in the system (NH4)(w)HgxCly(H2O)(z) with w : x : y : z=1 : 5 : 11 : 0, 2 : 3 : 8 : 1, 4 : 3 : 10 : 2, 2 : 1 : 4 : 1, and 10 : 3 : 16 : 0

Five new compounds in the system (NH4)Cl/HgCl2/H2O have been obtained as colourless single crystals, (NH4)Hg5Cl11, (NH4)(2)Hg3Cl8(H2O), (NH4)(4)Hg3Cl10(H2O)(2), (NH4)(2)HgCl4(H2O), and (NH4)(10)Hg3Cl16. In all of these, as in HgCl2 itself, (almost) linear HgCl2 molecules persist with Hg-Cl distances varying from 229 to 236 pm. In (NH4)(10)Hg3Cl16 there are also tetrahedra [HgCl4] with d(Hg-Cl) = 247 pm present. If larger Hg-Cl distances (of up to 340 pm) are considered as belonging to the coordination sphere of Hg-II, the structures may be described as consisting of isolated octahedra and tetrahedra as in (NH4)(10)Hg3Cl16, edge-connected chains as in (NH4)(2)HgCl4(H2O), edge-connected chains and layers of octahedra as in (NH4)(4)Hg3Cl10(H2O)(2), corrugated layers of edge-connected octahedra as in (NH4)(2)Hg3Cl8(H2O), and, finally, a three-dimensional network of connected six- and seven-coordinate Hg-Cl polyhedra as in (NH4)Hg5Cl11. The water molecules are never attached to Hg-II. The (NH4)(+) cations, and sometimes Cl- anions, play a role for electroneutrality only.

Afectividad evolutiva y diferencial de 10 a 16 años : estudio experimental a través del Z.Test.

Destacar la importancia que tiene la educación afectiva desde la infancia, y por ello los educadores deben asumir esa tarea, si quieren construir hombres equilibrados.. El trabajo ha sido realizado con un grupo de sujetos,elegidos al azar, divididos para su estudio de acuerdo con la edad y el sexo de los mismos. 280 sujetos de edades comprendidas entre 10 y 16 años. Estudiantes de EGB Y BUP, en su mayoría, y un número mínimo de Formación Profesional.. Los protocolos han sido recogidos en un número variable entre 30 y 60 sujetos según la referencia de Zulliger. Se ha tenido en cuenta las condiciones del aula y la edad de los sujetos. Reunido el grupo concreto al que se va a someter el test, y una vez cumplidas todas las instrucciones que señala Zulliger, cada sujeto responde en su hoja de protocolo. Una vez comenzada la prueba se debe controlar el tiempo de la misma, no debiendo pasar de 20 minutos.. En la primera parte se utilizan instrumentos de carácter bibliográfico, mientras que en la segunda, siendo de carácter práctico, se utiliza el test Z-test.. Elaboración estadística en la que se ha hallado el tanto por ciento.. Los resultados, más significativos, a los que se ha llegado han sido entre otros: Con respecto a la estructura propia de la afectividad, se puede afirmar que tanto los chicos como las chicas predomina el tipo de afectividad insuficientemente adaptada, lábil, impulsiva y sensible a los estímulos. Esto puede ser debido al momento físico y psicológico que estos sujetos están viviendo, pues es cuando se operan todos los cambios puberales, y es también cuando el sujeto se empieza a abrir a un mundo totalmente desconocido para él, y produce desequilibrio e inestabilidad, reflejándose en su afectividad. Sin embargo es preciso subrayar que esta impulsividad es más acusada en los chicos que en las chicas. En lo que respecta a la afectividad interior, hace que el tipo de afectividad lábil aparezca al exterior estabilizada y modificada en su dominio normal, significa que el sujeto la reprime de una manera natural por la introversión, la inteligencia y la visión de conjunto de la situación.. La prueba proyectiva de Z test nos permite llegar al estudio de la afectividad de una forma experimental a través de las respuestas provistas de contenido afectivo, e indirectamente a través del tipo vivencial de los sujetos. Con respecto a la afectividad interior resulta una afectividad lábil. El refrenado de la afectividad en su dominio normal es suficientemente aceptable en los dos sexos, aunque con una mejor proporción en las chicas. El tipo vivencial predominante en los dos sexos es el extratensivo. El indice de agresividad y de la adaptación social es mucho más elevado en las chicas que en los chicos. Ante esto, la postura del educador debe ser más que nunca en esta edad de diálogo, de apertura, de aceptación, de saber escuchar. Por ello tanto la familia como los educadores tienen parte activa en la educación afectiva de los adolescentes..

Genome-wide association study of CNVs in 16,000 cases of eight common diseases and 3,000 shared controls

Copy number variants (CNVs) account for a major proportion of human genetic polymorphism and have been predicted to have an important role in genetic susceptibility to common disease. To address this we undertook a large, direct genome-wide study of association between CNVs and eight common human diseases. Using a purpose-designed array we typed 19,000 individuals into distinct copy-number classes at 3,432 polymorphic CNVs, including an estimated 50% of all common CNVs larger than 500 base pairs. We identified several biological artefacts that lead to false-positive associations, including systematic CNV differences between DNAs derived from blood and cell lines. Association testing and follow-up replication analyses confirmed three loci where CNVs were associated with diseaseIRGM for Crohns disease, HLA for Crohns disease, rheumatoid arthritis and type 1 diabetes, and TSPAN8 for type 2 diabetesalthough in each case the locus had previously been identified in single nucleotide polymorphism (SNP)-based studies, reflecting our observation that most common CNVs that are well-typed on our array are well tagged by SNPs and so have been indirectly explored through SNP studies. We conclude that common CNVs that can be typed on existing platforms are unlikely to contribute greatly to the genetic basis of common human diseases. © 2010 Macmillan Publishers Limited. All rights reserved.

Breakdown voltage and V-Z characteristics of sodium vapour using coaxial cylindrical electrodes

Experimental results for breakdown voltage of sodium vapour measured for the first time using coaxial cylindrical electrodes of fixed gap distance (5 mm) and pressure (corrected to2 0 "C) in the range2 1 to 652 Pa are reported, and are founfdo l ltoow Paschen's Law. The investigations also reveal that V th-Ie characteristics are pressure dependent; the current during the breakdown and the buoifl dc-uurpre nt after a breakdoiws nei ther positive or negative. in spite of the central cylinder being always maintained at a positive potential

(Z)-11-Hexadecenal and (3Z,6Z,9Z)-Tricosatriene: Sex Pheromone Components of the Red Banded Mango Caterpillar Deanolis sublimbalis

The sex pheromone of the red banded mango caterpillar, Deanolis sublimbalis (Lepidoptera: Crambidae), a serious pest of the mango Mangifera indica (Anacardiaceae) in India and Southeast Asia and a recent invader into northern Australia, has been identified. Three candidate compounds were identified from pheromone gland extracts of female moths, using gas chromatography (GC), GC-electroantennographic detection and GC-mass spectrometric analyses, in conjunction with dimethyldisulfide derivatization. Field bioassays established that both (Z)-11-hexadecenal (Z11-16:Ald) and (3Z,6Z,9Z)-tricosatriene (3Z,6Z,9Z-23:Hy) were required for attraction of male D. sublimbalis moths, and 1,000 μg of a 1:1 mix of Z11-16:Ald and 3Z,6Z,9Z-23:Hy was more attractive to male moths than caged virgin females. However, the binary blend was only attractive when the isomeric purity of the monounsaturated aldehyde was >99%, suggesting that the (E)-isomer was inhibitory. Although (Z)-11-hexadecen-1-ol (Z11-16:OH) was tentatively identified in gland extracts, the addition of this compound to the binary blend did not increase the numbers of moths captured. The pheromone can now be used in integrated pest management strategies.

Structure of l-Diphenylmethyl-3-hydroxyazetidinium Chloride,* C 16 H lsN O+.CI -

M r=275.8, monoclinic, P21/a, a= 12.356 (5), b=9.054 (4), c= 14.043 (4) A, t= 100.34 (3) ° , V=1545.5A 3, Z=4, D,,,= 1.14, D x = 1.185 Mg m -3, p(Mo Ka, /l = 0.7107 ]k) = 2.77 mm -1, F(000) = 584.0, T= 293 K, R = 0.053 for 1088 reflections. The four-membered ring is buckled 13.0 ° (0= 167.0°). The azetidinium moiety is linked to the C1- ion through a hydrogen bond [O-H...C1 = 3.166 (5) A].

Modular design of synthetic protein mimics. Crystal structures, assembly, and hydration of two 15- and 16-residue apolar, leucyl-rich helical peptides

Two IS- and 16-residue peptides containing a-aminoisobutyric acid (Aib) have been synthesized, as part of a strategy to construct stereochemically rigid peptide helices, in a modular approach to design of protein mimics. The peptides Boc-(Val-Ala-Leu-Aib),-OMe ( I ) and Boc-Val-Ala-Leu-Aib-Val-Ala-Leu-(Val-Ala-Leu-Aib()11z)- OhaMvee been crystallized.Both crystals are stable only in the presence of mother liquor or water. The crystal data are as follows. I: C78H140N16019~2H20,P2,, a = 16.391 (3) A, b = 16.860 (3) A, c = 18.428 (3) A, p = 103.02 (I)O, Z = 2, R = 9.6% for 3445 data with lFol >30(F), resolution 0.93 A. 11: C7,Hl,,N,S018.7.5H,0, C2221, a = 18.348 ( 5 ) A, b = 47.382 (1 1) A, c = 24.157 ( 5 ) A, Z =8, R = l0,6%, for 3147 data with lFol > 3a(F), resolution 1.00 A. The 15-residue peptide (11) is entirely a helical, while the 16-residue peptide ( I ) has a short segment of 310 helix at the N terminus. The packing of the helices in the crystals is rather incfficicnt with no particular attractions between Leu-Leu side chains, or any other pair. Both crystals have fairly large voids, which are filled with water molecules in a disordered fashion. Water molecule sites near the polar head-to-tail regions are well detcrmined, those closer to the hydrophobic side chains less so and a number of possible water sites in the remaining "empty" space are not determined. No interdigitation of Leu side chains is observed in the crystal as is hypothesized in the "leucine zipper" class of DNA binding proteins.