Stereospecific four-bond phosphorus-phosphorus spin couplings in phosphazenyl-phosphazenes

Four-bond phosphorus-phosphorus coupling constants have been measured from the 31P NMR spectra of phosphazenylcyclophosphazenes. Their magnitude appears to be related to the conformation adopted by the phosphazenyl-group relative to the phosphazene ring

Publication ethics in public health emergencies

In this article, we describe and analyse three issues in publication ethics that are raised when conducting research in emergencies and disasters. These include reluctance to share data and samples because of concerns about publications, loss of individual authorship in high high-profile multi-entity publications, and the deaths of authors during dangerous research projects. An emergency research pledge may be useful in avoiding some of these issues

An investigation of some reactions of aluminium hydroborate

The reaction of aluminium hydroborate with alcohols and thiols is discussed, and this is extended to cover possible mechanisms for hydrolysis. The course of the reaction was found to be dependent on the structural type of alcohol or thiol used. Substitution of a thio alkyl group for hydroborate led to preparation of the type of compound RSA1(BH₄ )₂ (where R = methyl, ethyl, benzyl) and properties of these compounds are discussed. Using an exchange reaction of aluminium hydroborate with alkyl borates , corresponding compounds of the type RO Al(BH₄)₂ (R = methyl, ethyl) were prepared, and their properties ascertained. The behaviour of aluminium hydroborate with triethyl and trimethyl borane is considered. This work suggests that there is an exchange between the terminal hydrogens of the hydroborate groups and the borane alkyl groups, resultingin B-a!kylated aluminiumhydroborates. B-alkylated hydroborates a real so believed to be formed from a novel reaction between triethyl a lane and tetraethyl diborane. Some chemistryof the octahydrotriborate group linked to aluminium is also discussed. Starting from dimethyl aluminiumoctahydrotriborate an exchange reaction with excess aluminiumhydroborate yields aluminiumoctahydrotriborate bis hydroborate. The properties of both compounds are discussed, and the relevance of the latter to aluminium hydroborate decomposition is noted. The practical work involved extensive use of vacuum line and inert atmosphere techniques, and infra-red and n.m.r.spectral details were very useful

Competitive formation of spiro and ansa derivatives in the reactions of tetrafluorobutane-1,4-diol with hexachlorocyclotriphosphazene: a comparison with butane-1,4-diol

Reaction of hexachlorocyclotriphosphazene, N3P3Cl6 (1), in two stoichiometries (1:1.2 and 1:3) with the sodium derivative of the fluorinated diol, 2,2,3,3-tetrafluorobutane-1,4-diol, (2), in THF solution at room temperature afforded six products, whose structures have been characterized by X-ray crystallography and 1H, 19F and 31P NMR spectroscopy: the mono-spiro compound, N3P3Cl4(OCH2CF2CF2CH2O), (3), its ansa isomer, (4), a di-spiro derivative N3P3Cl2(OCH2CF2CF2CH2O)2, (5), its spiro-ansa (6) and non-gem cis bis-ansa (7) isomers and a tri-spiro compound N3P3(OCH2CF2CF2CH2O)3, (8). The tri-spiro derivative (8) was also formed in the reaction of the ansa compound (4) with diol (2) in a 1:3 ratio in THF at room temperature. The reactions of (1) with step-wise additions of (2) were also investigated at low temperature (-780C) to give the same range of products as at room temperature. The results of all reactions are compared with previous work on the reactions of (1) with butane-1,4-diol/pyridine mixtures and with the reaction of hexafluorocyclotriphosphazene, N3P3F6 (9), with the silyl derivative of the diol (2), (Me3SiOCH2CF2)2, in a 1:0.4 mole ratio in the same solvent, THF

Arabidopsis nucleolar protein database (AtNoPDB)

The Arabidopsis Nucleolar Protein Database (http://bioinf.scri.sari.ac.uk/cgi-bin/atnopdb/home) provides information on 217 proteins identified in a proteomic analysis of nucleoli isolated from Arabidopsis cell culture. The database is organized on the basis of the Arabidopsis gene identifier number. The information provided includes protein description, protein class, whether or not the plant protein has a homologue in the most recent human nucleolar proteome and the results of reciprocal BLAST analysis of the human proteome. In addition, for one-third of the 217 Arabidopsis nucleolar proteins, localization images are available from analysis of full-length cDNA–green fluorescent protein (GFP) fusions and the strength of signal in different parts of the cell—nucleolus, nucleolus-associated structures, nucleoplasm, nuclear bodies and extra-nuclear—is provided. For each protein, the most likely human and yeast orthologues, where identifiable through BLASTX analysis, are given with links to relevant information sources

Epidemic spreading in evolving networks

A model for epidemic spreading on rewiring networks is introduced and analyzed for the case of scale free steady state networks. It is found that contrary to what one would have naively expected, the rewiring process typically tends to suppress epidemic spreading. In particular it is found that as in static networks, rewiring networks with degree distribution exponent $\gamma >3$ exhibit a threshold in the infection rate below which epidemics die out in the steady state. However the threshold is higher in the rewiring case. For $2<\gamma \leq 3$ no such threshold exists, but for small infection rate the steady state density of infected nodes (prevalence) is smaller for rewiring networks.Comment: 7 pages, 7 figure

International study into the use of intermittent hormone therapy in the treatment of carcinoma of the prostate : A meta-analysis of 1446 patients

OBJECTIVE: To review pooled phase II data to identify features of different regimens of intermittent hormone therapy (IHT), developed to reduce the morbidity of treating metastatic prostate cancer, and which carries a theoretical advantage of delaying the onset of androgen-independent prostate cancer, (AIPC) that are associated with success, highlighting features which require exploration with prospective trials to establish the best strategies for using this treatment. METHODS: Individual data were collated on 1446 patients with adequate information, from 10 phase II studies with >50 cases, identified through Pubmed. RESULTS: Univariate and multivariate Cox proportional hazard models were developed to predict treatment success with a high degree of statistical success. The prostate-specific antigen (PSA) nadir, the PSA threshold to restart treatment, and medication type and duration, were important predictors of outcome. CONCLUSIONS: The duration of biochemical remission after a period of HT is a durable early indicator of how rapidly AIPC and death will occur, and will make a useful endpoint in future trials to investigate the best ways to use IHT based on the important treatment cycling variables described above. Patients spent a mean of 39% of the time off treatment. The initial PSA level and PSA nadir allow the identification of patients with prostate cancer in whom it might be possible to avoid radical therapy.Peer reviewe

Low-density open-cell foams in the NiTi system

It is shown that open-cell metallic foams having very low density, and that display martensite transformations required for shape memory and superelastic behavior, can be fabricated using a powder-metallurgy technique. Results are presented on experiments in which a polymeric precursor foam was coated with an equiatomic NiTi powder slurry and subsequently sintered to yield foams with relative densities as low as 0.039. Although contaminated with interstitial impurities, they displayed unambiguous calorimetric signature of the B2→B19′B2→B19′ transformation. The results are of considerable significance to potential applications requiring ultralightweight structures with the unusual dissipative and strain-recovery properties of NiTi shape-memory materials. © 2003 American Institute of Physics.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/71336/2/APPLAB-82-16-2727-1.pd

Superelastic NiTi honeycombs: fabrication and experiments

In this paper we demonstrate a new class of superelastic NiTi honeycomb structures. We have developed a novel brazing technique that has allowed us to fabricate Nitinol-based cellular structures with relative densities near 5%. Commercially available nickel-rich Nitinol strips were shape-set into corrugated form, stacked, and bonded at high temperature by exploiting a contact eutectic melting reaction involving pure niobium. After heat treatment to restore transformational superelastic response, prototype honeycomb structures were subjected to severe in-plane compression loading at room temperature. The specimens exhibited good specific strength, high specific stiffness, and enhanced shape recovery compared to monolithic shape memory alloys (SMAs). Compressive strains of over 50% could be recovered upon unloading. The demonstrated architectures are simple examples of a wide variety of possible built-up topologies, enabled by the bonding method, that can be engineered for customizable net section properties, arbitrary shape, and kinematically enhanced thermomechanical shape-memory and superelastic response.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/58146/2/sms7_1_S17.pd

Enhancing patients' autonomy by involving them in research ethics committees

Objective : Although clinical trial participants are the most affected by research ethics committee’s decisions, they are not formally represented on Swiss committees. We aimed to find out what patients think about the idea of being members of such committees. Design : Latent thematic analysis was used to analyse the interviews. Setting: Patients were recruited in a Swiss university hospital. Participants: The study involved 26 patients suffering from diabetes or gout. Interventions: We conducted semi-structured interviews. Main Outcome Measures: We explored what patients think of being established members of research ethics committees. Results : We identified three different attitudes among our participants regarding participation in research ethics committees: 1) positive attitude regarding the idea of being members of such committees 2) ambivalent attitude and 3) negative attitude. Patients belonging to the first group 1) often mentioned that they wanted their health condition to be more visible. Patients from the second group 2) mentioned positive as well as negative aspects. Patients from the third group 3) said that patients in general did not have enough background knowledge to be able to gain an overview of a whole clinical trial. Conclusions: Our study adds important knowledge about the idea of patients becoming research ethics committee members by exploring their perceptions of being members. Stable patients tended to be interested in the idea of participation and some specific recommendations could be derived (patients could have an advisory instead of a decision-making role on committees). However, further studies with more patients and further quantitative research are needed