Hydrogen Bond Dynamics of Cellulose through Inelastic Neutron Scattering Spectroscopy.

This work explores the dynamics of hydrogen bond networks in cellulose through inelastic neutron scattering (INS) and periodic CASTEP calculations. Estimated spectra were based on the crystal structure of cellulose Iα and Iß and replicate the INS spectrum of cellulose samples with remarkable similarity, allowing a reliable assignment of INS bands to vibrational modes of cellulose. Comparison of cellulose samples from varied sources, from bacterial to kraft pulp, allows the identification of characteristic INS bands, arising from C2-OH torsional motions, which easily identify which allomorph-Iα or Iß-is prevalent. A high crystallinity index is revealed by the presence of well-defined INS bands associated with highly cooperative CH bending modes along the chain. Hydrating kraft cellulose samples clearly affects those INS bands related with the hydroxymethyl group, identified as the preferred binding site for water molecules. At high humidity content level, a significant proportion of the water molecules is aggregated in clusters within the amorphous cellulose domains. The formation of ice microcrystals leads to a partial disruption of the hydrogen-bond network, as can be concluded from the observed red-shift of the torsional OH vibrational modes. The full assignment and interpretation of cellulose's INS spectra herein provided is a sound basis for future use of INS spectroscopy in the characterization of functionalized cellulose fibers and composite materials.

The effect of ionic Co presence on the structural, optical and photocatalytic properties of modified cobalt-titanate nanotubes.

With the aim of producing materials with enhanced optical and photocatalytic properties, titanate nanotubes (TNTs) modified by cobalt doping (Co-TNT) and by Na(+)→ Co ion-exchange (TNT/Co) were successfully prepared by a hydrothermal method. The influence of the doping level and of the cobalt position in the TNT crystalline structure was studied. Although no perceptible influence of the cobalt ion position on the morphology of the prepared titanate nanotubes was observed, the optical behaviour of the cobalt modified samples is clearly dependent on the cobalt ions either substituting the Ti(4+) ions in the TiO6 octahedra building blocks of the TNT structure (doped samples) or replacing the Na(+) ions between the TiO6 interlayers (ion-exchange samples). The catalytic ability of these materials on pollutant photodegradation was investigated. First, the evaluation of hydroxyl radical formation using the terephthalic acid as a probe was performed. Afterwards, phenol, naphthol yellow S and brilliant green were used as model pollutants. Anticipating real world situations, photocatalytic experiments were performed using solutions combining these pollutants. The results show that the Co modified TNT materials (Co-TNT and TNT/Co) are good catalysts, the photocatalytic performance being dependent on the Co/Ti ratio and on the structural metal location. The Co(1%)-TNT doped sample was the best photocatalyst for all the degradation processes studied.

Bacterial cellulose membranes as drug delivery systems: an in vivo skin compatibility study.

Bacterial cellulose (BC) is a highly pure form of cellulose, produced in the form of a swollen membrane by several bacteria that demonstrated to be able to modulate the skin release of model drugs. In the present study, the skin irritation potential of BC was evaluated in human subjects. BC membranes with and without glycerin (acting as plasticizer) were tested. No significant differences were observed for transepidermal water loss (TEWL) measurements in comparison with negative control, 2 and 24 h after patch removal, which is an indicator of an absence of barrier disruption. Similar results were found for erythema. Clinical scores were zero at both times for all volunteers, with the exception of five volunteers that exhibited weak reactions. BC with glycerin provided a skin moisturizing effect statistically higher than the negative control (p=0.044), which was not observed for BC alone. The good skin tolerance found after a single application under occlusion reinforces the putative interest of BC membranes as supports for drug topical delivery. Besides modifying the mechanical properties, the inclusion of glycerin results in a skin moisturizing effect which could be clinically relevant for the treatment for skin diseases characterized by dryness, such as psoriasis and atopic dermatitis.

Photodegradation of the fungicide thiram in aqueous solutions. Kinetic studies and identification of the photodegradation products by HPLC-MS/MS.

In this study, the relevance of photodegradation processes on the persistence of the fungicide thiram in waters was investigated. The photodegradation of thiram in Milli-Q water and in aqueous solutions of humic and fulvic acids, as well as the photodegradation in spiked river water were studied. Both pure thiram and one of its commercial formulations were used to prepare the solutions which were irradiated in a solar light simulator. In general, thiram photodegradation follows pseudo-first order kinetics. The half-life time of thiram 2mgL(-1) in Milli-Q water was 28min. However, the degradation rate of thiram was significantly increased (p=0.02) by the inert components of the thiram commercial formulation as well as by commercial humic acids and by fulvic acids isolated from river water (p<0.004). Thus, the half-life time of thiram decreased to 24min in the presence of the inert formulation components, while, in the presence of both humic and fulvic acids (10mgL(-1)) it decreased to 22min. Furthermore, thiram photodegradation in natural river water showed that there is a significant enhancement of the degradation rate constant of thiram relatively to Milli-Q water, corresponding to a decrease of about 38% in its half-life time. This increase of the degradation rate in river water seems to be higher than that observed in the presence of FA, suggesting that beyond organic matter, other natural river components can increase the thiram photodegradation rate. These results allow us to conclude that photodegradation by solar radiation can be an important degradation pathway of thiram in natural waters. HPLC-MS/MS allowed to identify, for the first time, three products of the photodegradation of thiram in aqueous solution. Three compounds were identified and their structure was corroborated by the MS(n) spectra fragmentation profile. Pathways for the formation of the products from thiram photodegradation are proposed and discussed.

Ferromagnetic order in aged Co-doped TiO2 anatase nanopowders.

This paper reports on the ferromagnetic properties of aged Ti(1-x)CoxO(2-delta) anatase nanopowders with different Co contents (0.03 < or = x < or = 0.10). It is shown for the first time that aged Co:TiO2 anatase samples retain rather high values of magnetization (M), remanence (Mr) and coercivity (Hc) which provide strong evidence for a preserved long-range ferromagnetic order. Room temperature M, Mr and Hc values were measured in the ranges of [0.05, 0.79] microB/Co, [0.044, 0.096] microB/Co and [366.7,494.8]Oe, respectively, which are in the same range as in general reported either for newly prepared thin films or nanoparticles.

Coexistence of universal and topological anomalous hall effects in metal CrO2 thin films in the dirty limit.

The scaling exponent of 1.6 between anomalous Hall and longitudinal conductivity, characteristic of the universal Hall mechanism in dirty-metal ferromagnets, emerges from a series of CrO2 films as we systematically increase structural disorder. Magnetic disorder in CrO2 increases with temperature and this drives a separate topological Hall mechanism. We find that these terms are controlled discretely by structural and magnetic defect populations, and their coexistence leads to apparent divergence from exponent 1.6, suggesting that the universal term is more prevalent than previously realized.

Miscanthus x giganteus extractives: a source of valuable phenolic compounds and sterols.

The chemical composition of the lipophilic extracts of bark and core, of the Miscanthus x giganteus stalk, was studied by gas chromatography-mass spectrometry (GC-MS). Aromatic compounds, sterols, and fatty acids, followed by long-chain fatty alcohols, were the major families of components present in the M. x giganteus stalk. Aromatic compounds are more abundant in the M. x giganteus bark (521 mg/kg of bark), with vanillic acid, vanillin, and p-hydroxybenzaldehyde as the major compounds of this family. In the M. x giganteus core, sterols represent about 949 mg/kg of dry core with beta-sitosterol, 7-oxo-beta-sitosterol, stigmasterol, and campesterol as the major components. The detection of small amounts of esters in the GC-MS analysis with short columns explains the small increase in the abundance of the identified families after alkaline hydrolysis. The high content of valuable sterols and aromatic compounds in M. x giganteus and, particularly, in the core, which is considered a residue in most applications, can open new perspectives for the integrated upgrading of this grass within the biorefinery perspective.

Genotype and sex effects on carcass and meat quality of suckling kids protected by the PGI "Cabrito de Barroso".

Carcass composition and meat quality traits were evaluated in 55 suckling kids (27 males and 28 females) from Serrana (S), Bravia (B) and Serrana×Bravia (S×B) crossbred genotypes. Kids were slaughtered at 8-11kg of live weight according to "Cabrito de Barroso-PGI" specifications and carcasses' left sides were totally dissected. Dressing percentage (based on ELW) did not vary between genotypes and sexes. Genotype B carcasses have better conformation, expressed in higher compactness index and muscle/bone ratio. Sex had no effect on the composition of dissected carcass but females deposited more internal fat than males. S genotype had significantly less muscle content and higher dissectible fat compared to B and S×B genotypes, suggesting differences in maturity stages. The carcass' bone content (20.4-21.4%) did not differ significantly between genotypes. The longissimus thoracis et lumborum (LTL) and gluteobiceps (GB) muscles were used for meat quality determinations. Genotype had a significant effect on meat traits and fatty acid composition of the analysed muscles: B genotype and LTL muscle showed lower final pH, S×B genotype had darker and more red muscles, GB muscle had a higher shear force value and lower collagen solubility. Few sex effects were observed on meat quality traits as well as on fatty acid composition. Average percentage of desirable fatty acids in kids was superior to 60% with male S genotype displaying a lower value. Genotypes B and B×S, males and GB muscle had more favorable PUFA:SFA ratios.

Prevalence of chlamydia and gonorrhoea among a population of men who have sex with men.

OBJECTIVES: Few data are available on the prevalence of sexually transmitted diseases (STDs) in men who have sex with men (MSM), making it difficult to develop STD screening guidelines for this population. The objective of the study was to determine the prevalence of urethral infections caused by Chlamydia trachomatis and Neisseria gonorrhoeae within a large, community based population of MSM, and to assess the feasibility of rectal screening in this population. METHODS: This was a cross sectional study of 566 MSM, who were predominantly middle aged, white, asymptomatic, and engaged in sex with multiple partners. All provided a urine sample to screen for chlamydial and gonorrhoea infections using a PCR assay; rectal screening was performed on 48 participants. RESULTS: Urethral C. trachomatis infections were detected in 1/566 participants (prevalence 0.2%, 95% CI 0.004% to 1.0%), and rectal C. trachomatis infections were detected in 2/48 men (prevalence 4.2%, 95% CI 0.5% to 14.2%). No gonorrhoea infections were detected, and none of the 117 HIV positive men had either infection. CONCLUSIONS: Chlamydial and gonorrhoea infections were uncommon in this sample of MSM, even among those with multiple sexual partners or HIV infection. These data call into question recommendations to screen all MSM based on their individual sexual behaviours or HIV. Additional data are needed on the prevalence of these infections in MSM from different settings.

Lignanamides and other phenolic constituents from the bark of kenaf (Hibiscus cannabinus).

Two new acyclic phenylpropane lignanamides, grossamide K and erythro-canabisine H, and the naphthol glucoside 2,5-dimethyl-3-O-beta-D-glucopyranosylnaphthol, along with six known compounds were isolated from the acetone extract of bark of Hibiscus cannabinus. All structures were established by spectroscopic methods including 2D NMR techniques, which allowed the correction of certain previously reported 13C NMR assignments of grossamide.

Phenolic constituents from the core of kenaf (Hibiscus cannabinus).

Four lignans, boehmenan H [2-(4-hydroxy-3-methoxyphenyl)-5-[3-(4-hydroxy-3-methoxycinnamoyloxy)propyl]-3-hydroxymethyl-7-methoxybenzodihydrofuran], boehmenan K [2-(4-hydroxy-3-methoxyphenyl)-5-[3-(4-hydroxycinnamoyloxy)-1-propenyl]-3-(4-hydroxy-3-methoxycinnamoyloxymethyl)-7-methoxybenzodihydrofuran], threo-carolignan H [threo-1-(4-hydroxy-3-methoxyphenyl)-2-[4-[3-(4-hydroxy-3-methoxycinnamoyloxy)propyl]-2-methoxyphenoxy]-1,3-propanodiol], and threo-carolignan K [threo-1-(4-hydroxy-3-methoxyphenyl)-3-(4-hydroxy-3-methoxycinnamoyloxy)-2-[4-[3-(4-hydroxycinnamoyloxy)-1-propenyl]-2-methoxyphenoxy]-1-propanol] as well as several other lignans, aldehydes and a tyramine derivative were isolated from the acetone extract of core of kenaf (Hibiscus cannabinus). All the structures were established by spectroscopic methods. The hitherto unreported 13C NMR spectra of some compounds are also presented and discussed. 2D NMR techniques have allowed the revision of certain previously reported 13C NMR assignments of some scarce naturally occurring compounds.

A participant observation study using actors at 30 publicly funded HIV counseling and testing sites in Pennsylvania.

OBJECTIVES: This study was designed to augment an evaluation of Pennsylvania publicly funded HIV counseling and testing sites, particularly of the staff-client interaction. METHODS: Actors were trained as research assistants and sent to 30 randomly chosen sites to be tested and counseled for HIV disease. Instruments based on Centers for Disease Control and Prevention (CDC) guidelines were designed and used to evaluate them. RESULTS: Data were generated that identified the range of compliance with CDC guidelines and state policy. Among the findings were that 10 of 30 sites required signed consents despite a state policy allowing anonymous testing. Only 17% of providers developed a written risk reduction plan, even though 69% of all sites surveyed by mail asserted that such plans were developed. Only 2 of 5 HIV-positive actors were offered partner notification services, even though 100% of sites visited by an interviewer claimed to offer such services. CONCLUSIONS: The findings suggest that although evaluation methods such as mail surveys and site visits are useful for evaluating the existence of appropriate policies and protocols and gathering baseline data, they might not be sufficient for assessing actual staff-client interaction.

Structural characterization of the lignin from the nodes and internodes of Arundo donax reed.

Milled wood lignin (MWL) and dioxane lignin (DL) from different morphological regions (nodes and internodes) of Arundo donax reed were subjected to a comprehensive structural characterization by (13)C, (1)H NMR, FTIR, and UV spectroscopies and functional analysis. The permanganate and nitrobenzene oxidation methods were also applied to the in situ lignins. Both node and internode lignins are HGS-type lignins, with a significant amount of H units (including p-coumaric acid type structures). The S/G ratio (1.13-1.32), the weight-average molecular weight (20,400-24,500), the methoxyl group content (0.90-0.98), the phenolic hydroxyl group content (0.23-0.27), and the aliphatic hydroxyl group content (1.00-1.09) are not very different in the lignins from nodes and internodes. However, some structural differences between node and internode lignins were observed. The former has much more phenolic acids (p-coumaric and ferulic), 8.8% in node versus 1.2% in internode and less beta-O-4 (0. 32 and 0.49 per aromatic unit in node and internode, respectively). In situ node lignin is more condensed than internode lignin.

Composition of suberin extracted upon gradual alkaline methanolysis of Quercus suber L. cork.

The monomeric composition of suberin extracts obtained by gradual alkaline methanolysis of Quercus suber cork was determined by gas chromatography-mass spectrometry (GC-MS). Results show that 1-alkanols and alkanoic and alpha,omega-alkanedioic acids are preferentially removed upon mild alkaline conditions, whereas mid-chain-modified omega-hydroxyalkanoic acids are preferentially removed under stronger alkaline conditions. Saturated omega-hydroxyalkanoic acids are found to be abundant in all suberin extracts. These results are consistent with two distinct suberin fractions with different locations in cork cell walls and/or esterification degrees. It is proposed that these fractions correlate with the two main suberin peaks in the solid state (13)C NMR spectra of cork and suberin extracts. Quantitative GC-MS analysis showed that suberin monomers comprise approximately 30% (w/w) of the suberin extracts, the remaining comprising nonvolatile structures with high M(n) values, as measured by vapor pressure osmometry. The presence of a large fraction of high molecular weight aliphatic structures in suberin extracts is supported by the corresponding NMR spectra.

Gay male, lesbian and bisexual health-related research funded by the National Institutes of Health between 1974 and 1992.

Health-related problems among lesbians, bisexuals, and gay men require research before solutions to them can be identified. This paper describes NIH sponsored research listing homosexuality as a primary or secondary issue between 1974 and 1992. Homosexual projects unrelated to HIV and excluding capitol funding averaged only $532,000 per year compared to about $20 million per year since 1982 for HIV projects. Considering the range of health threats to these communities and the amounts needed to deal with HIV alone, current funding is clearly inadequate. Community members, scientists, experts, and others need to take action if appropriate research is to be done and the health needs of these groups are to be addressed.

Cork suberin as a new source of chemicals. 1. Isolation and chemical characterization of its composition.

Extractive-free cork from Quercus suber L. was submitted to a solvolysis treatment with methanolic NaOH which yielded 37% (o.d. cork) of suberin. This mixture of compounds was thoroughly characterized by FTIR, 1H- and 13C-NMR, gas chromatography coupled with mass spectrometric (GC-MS) analysis, vapour pressure osmometry (VPO), mass spectrography (MS) and gel permeation chromatography (GPC). After derivatization, the main components of the volatile fraction, representing less than half of the total, were found to be omega-hydroxymonocarboxylates, alpha, omega-dicarboxylates, simple alkanoates and 1-alkanols, all with chain lengths ranging from C16 to C24. A second fraction, with an average molecular weight about three times higher, was detected by VPO, MS and GPC. The presence of this important fraction in cork suberin had not been recognized in earlier studies. Both fractions constitute interesting precursors for the elaboration of new materials.

Anal sphincter structure and function in homosexual males engaging in anoreceptive intercourse.

OBJECTIVES: To evaluate the structure and function of the internal (IAS) and external (EAS) anal sphincters in anoreceptive homosexual men and to determine whether anoreceptive intercourse (ARI) is associated with a higher risk of incontinence in this population. METHODS: We studied 14 anoreceptive homosexual males and 10 age-matched non-anoreceptive heterosexual males in a controlled, prospective cohort study. Subjects underwent evaluation of resting and maximum squeeze anal canal pressures (maximum squeeze pressure obtained over resting pressure) by station pull-through technique, using a manometric perfusion catheter followed by endoanal ultrasonography to evaluate the structure of the IAS and EAS. Manometry also was performed in age-matched male controls. All subjects completed a questionnaire that assessed sexual practices and bowel habits, including fecal incontinence. RESULTS: Resting pressures were significantly lower in subjects engaging in ARI (70.7 +/- 3.2 mm Hg vs. 91.4 +/- 5.2 mm Hg; mean +/- SEM, p < 0.003), whereas there was no significant difference in the mean maximum squeeze pressures, compared with controls (177.1 +/- 14.1 mm Hg vs. 151.8 +/- 19.6 mm Hg; mean +/- SEM, p = 0.32). No disruptions of the IAS or EAS were identified in either the anoreceptive or control group. Anoreceptive men tended to have thinner anal sphincters than controls, but the difference was not statistically significant. Furthermore, there were no complaints of fecal incontinence by the study subjects. CONCLUSIONS: Passive ARI is associated with decreased resting anal canal pressures, but total pressures are normal. There were no IAS or EAS defects, as well as no fecal incontinence, in our subjects. Better relaxation of the ARI subjects during anal canal manometry may explain the lower resting pressures.

Brokering: a process for establishing long-term and stable links with gay male communities for research and public health education.

The success of efforts to prevent continued transmission of the human immunodeficiency virus (HIV) and to increase compliance with HIV prophylactic interventions among homosexual and bisexual men will depend in part on health care professionals' understanding of and ability to establish linkages with these men. In order to recruit men into a research project and an educational program, staff at the Pitt Men's Study, an epidemiological investigation of HIV infection, developed a process described here as "brokering," which was based on community organizing and marketing principles. Brokering is a dynamic process by which researchers and public health professionals exchange goods and services with formal and informal leaders of the gay community in order to establish strong, long-term linkages. To date, this process yielded 2,989 homosexual and bisexual recruits into the study, which began in 1983. After 8 years, 79% of those still alive continue to return for follow-up. While recruitment techniques will need to vary from city to city, the importance of establishing linkages with the local indigenous leadership remains of major importance.

Factors associated with participation in HIV antibody screening and results disclosure.

The Centers for Disease Control reported in October 1991 that many people at risk for human immunodeficiency virus (HIV) infection had not been tested for antibodies to HIV. This study identifies differences among 110 gay and bisexual men in three small cities in Pennsylvania who decided whether to be tested for antibodies to HIV and, if so, whether to return for results. These men were given self-administered questionnaires and were offered free and confidential HIV antibody tests. Fifty percent of the men refused testing. Of those tested, only 35 percent returned to obtain test results. Contrary to other health prevention data, education was significantly and inversely related to being tested and to returning for results. Men who most often participated in the institutionalized gay community were least likely to be tested. The findings suggest that gay men who are most aware of the potential psychosocial problems associated with HIV antibody testing are more likely to avoid testing.