Slip versus Slop: A Head-to-Head Comparison of UV-Protective Clothing to Sunscreen.

Ultraviolet radiation (UVR) exposure is the most important modifiable risk factor for skin cancer development. Although sunscreen and sun-protective clothing are essential tools to minimize UVR exposure, few studies have compared the two modalities head-to-head. This study evaluates the UV-protective capacity of four modern, sun-protective textiles and two broad-spectrum, organic sunscreens (SPF 30 and 50). Sun Protection Factor (SPF), Ultraviolet Protection Factor (UPF), Critical Wavelength (CW), and % UVA- and % UVB-blocking were measured for each fabric. UPF, CW, % UVA- and % UVB-blocking were measured for each sunscreen at 2 mg/cm2 (recommended areal density) and 1 mg/cm2 (simulating real-world consumer application). The four textiles provided superior UVR protection when compared to the two sunscreens tested. All fabrics blocked erythemogenic UVR better than the sunscreens, as measured by SPF, UPF, and % UVB-blocking. Each fabric was superior to the sunscreens in blocking full-spectrum UVR, as measured by CW and % UVA-blocking. Our data demonstrate the limitations of sunscreen and UV-protective clothing labeling and suggest the combination of SPF or UPF with % UVA-blocking may provide more suitable measures for broad-spectrum protection. While sunscreen remains an important photoprotective modality (especially for sites where clothing is impractical), these data suggest that clothing should be considered the cornerstone of UV protection.

Infrared radiative properties and thermal modeling of ceramic-embedded textile fabrics.

The infrared optical properties of textiles are of great importance in numerous applications, including infrared therapy and body thermoregulation. Tuning the spectral response of fabrics by the engineering of composite textile materials can produce fabrics targeted for use in these applications. We present spectroscopic data for engineered polyester fabric containing varying amounts of ceramic microparticles within the fiber core and report a spectrally-dependent shift in infrared reflectance, transmittance and absorptance. A thermal transport model is subsequently implemented to study the effect of these modified properties on the spectral distribution of infrared radiation incident upon the wearer of a garment constructed of this fabric.

Engineered emissivity of textile fabrics by the inclusion of ceramic particles.

Composite textile materials, created from a blend of different fibers, have long been used to engineer the properties and performance of fabrics to combine comfort with functionality, such as to create materials with differing optical properties. Some changes to the optical properties of materials in the infrared are subtle and difficult to measure. We present a measurement technique, experimental apparatus, and associated data analysis procedure for detecting small changes in the emissivity of fabrics in the mid-infrared wavelength range (7.5-14 µm). Using this technique, we demonstrate that the emissivity of polyester fabric can be engineered controllably via the inclusion of ceramic microparticles within the fabric fibers.

Nanoparticle dispersion in polymer nanocomposites by spin-diffusion-averaged paramagnetic enhanced NMR relaxometry: scaling relations and applications.

Scaling relationships are identified between NMR longitudinal relaxation times and clay dispersion quality in polymer-paramagnetic clay nanocomposites. Derived from a previously published analytical relationship developed from a lamella-based model, the scaling relationships are based on the enhancement of NMR relaxation rates with increasing exfoliation and dispersion homogeneity. The paramagnetic contribution to the NMR relaxation rate is inversely proportional to the square of the clay interparticle spacing, and directly proportional to the square of the clay weight fraction. These scaling relationships allow the prediction of relative exfoliation of clay particles for a given series of polymer-clay nanocomposites. With independent knowledge of clay exfoliation in a single sample (e.g., from transmission electron microscopy), NMR relaxometry data may be converted into absolute measures of exfoliation. These scaling relations are confirmed with samples of fully exfoliated poly(vinyl alcohol)-montmorillonite nanocomposites, and then used to reveal exfoliation and dispersion quality in a series of nylon-6-montmorillonite nanocomposites. This characterization route is advantageous because NMR relaxometry can more rapidly provide clay dispersion information that is averaged over larger sample volumes than transmission electron microscopy.

Nanoparticle dispersion in polymer nanocomposites by spin-diffusion-averaged paramagnetic enhanced NMR relaxometry.

We developed an analytical relationship between nuclear magnetic relaxation and interparticle spacings in polymer nanocomposites filled with paramagnetic-impurity-containing clay nanoparticles. Using (1)H NMR relaxometry, clay nanoparticle dispersion was quantified and agrees with interparticle spacing distributions determined from statistical analysis of TEM images. Some information on the overall quality of clay dispersion is revealed. This work offers a new approach and new insights into nanoparticle dispersion in polymer nanocomposites.

The Stanford Leisure-Time Activity Categorical Item (L-Cat): a single categorical item sensitive to physical activity changes in overweight/obese women.

BACKGROUND: Physical activity is essential for chronic disease prevention, yet <40% of overweight/obese adults meet the national activity recommendations. For time-efficient counseling, clinicians need a brief, easy-to-use tool that reliably and validly assesses a full range of activity levels, and, most importantly, is sensitive to clinically meaningful changes in activity. The Stanford Leisure-Time Activity Categorical Item (L-Cat) is a single item comprising six descriptive categories ranging from inactive to very active. This novel methodological approach assesses national activity recommendations as well as multiple clinically relevant categories below and above the recommendations, and incorporates critical methodological principles that enhance psychometrics (reliability, validity and sensitivity to change). METHODS: We evaluated the L-Cat's psychometrics among 267 overweight/obese women who were asked to meet the national activity recommendations in a randomized behavioral weight-loss trial. RESULTS: The L-Cat had excellent test-retest reliability (κ=0.64, P<0.001) and adequate concurrent criterion validity; each L-Cat category at 6 months was associated with 1059 more daily pedometer steps (95% CI 712-1407, ß=0.38, P<0.001) and 1.9% greater initial weight loss at 6 months (95% CI -2.4 to -1.3, ß=-0.38, P<0.001). Of interest, L-Cat categories differentiated from each other in a dose-response gradient for steps and weight loss (Ps<0.05) with excellent face validity. The L-Cat was sensitive to change in response to the trial's activity component. Women increased one L-Cat category at 6 months (M=1.0±1.4, P<0.001); 55.8% met the recommendations at 6 months whereas 20.6% did at baseline (P<0.001). Even among women not meeting the recommendations at both baseline and 6 months (n=106), women who moved 1 L-Cat categories at 6 months lost more weight than those who did not (M=-4.6%, 95% CI -6.7 to -2.5, P<0.001). CONCLUSIONS: Given strong psychometrics, the L-Cat has timely potential for clinical use such as tracking activity changes via electronic medical records, especially among overweight/obese populations who are unable or unlikely to reach national recommendations.

Spatially resolved solid-state 1H NMR for evaluation of gradient-composition polymeric libraries.

Polyurethane libraries consisting of films with composition gradients of aliphatic polyisocyanate and hydroxy-terminated polyacrylate resin were characterized using methods of (1)H NMR microimaging (i.e., magnetic resonance imaging, (MRI)) and solid-state NMR. Molecular mobilities and underlying structural information were extracted as a function of the relative content of each of the two components. Routine NMR microimaging using the spin-echo sequence only allows investigations of transverse relaxation of magnetization at echo times >2 ms. A single-exponential decay was found, which is likely due to free, noncross-linked polymer chains. The mobility of these chains decreases with increasing content of the aliphatic polyisocyanate. The concept of a 1D NMR profiler is introduced as a novel modality for library screening, which allows the convenient measurement of static solid-state NMR spectra as a function of spatial location along a library sample that is repositioned in the rf coil between experiments. With this setup the complete transverse relaxation function was measured using Bloch decays and spin echoes. For all positions within the gradient-composition film, relaxation data consisted of at least three components that were attributed to a rigid highly cross-linked resin, an intermediate cross-linked but mobile constituent, and the highly mobile free polymer chains (the latter is also detectable by MRI). Analysis of this overall relaxation function measured via Bloch decays and spin echoes revealed only minor changes in the mobilities of the individual fractions. Findings with respect to the most mobile components are consistent with the results obtained by NMR microimaging. The major effect is the significant increase in the rigid-component fraction with the addition of the hydroxy-terminated polyacrylate resin.

Single-walled aluminosilicate nanotube/poly(vinyl alcohol) nanocomposite membranes.

The fabrication, detailed characterization, and molecular transport properties of nanocomposite membranes containing high fractions (up to 40 vol %) of individually-dispersed aluminosilicate single-walled nanotubes (SWNTs) in poly(vinyl alcohol) (PVA), are reported. The microstructure, SWNT dispersion, SWNT dimensions, and intertubular distances within the composite membranes are characterized by scanning and transmission electron microscopy (SEM and TEM), energy-dispersive spectroscopy (EDS), X-ray diffraction (XRD), XRD rocking curve analysis, small-angle X-ray scattering (SAXS), and solid-state NMR. PVA/SWNT nanocomposite membranes prepared from SWNT gels allow uniform dispersion of individual SWNTs in the PVA matrix with a random distribution of orientations. SAXS analysis reveals the length (∼500 nm) and outer diameter (~2.2 nm) of the dispersed SWNTs. Electron microscopy indicates good adhesion between the SWNTs and the PVA matrix without the occurrence of defects such as voids and pinholes. The transport properties of the PVA/SWNT membranes are investigated experimentally by ethanol/water mixture pervaporation measurements, computationally by grand canonical Monte Carlo and molecular dynamics, and by a macroscopic transport model for anisotropic permeation through nanotube-polymer composite membranes. The nanocomposite membranes substantially enhance the water throughput with increasing SWNT volume fraction, which leads to a moderate reduction of the water/ethanol selectivity. The model is parameterized purely from molecular simulation data with no fitted parameters, and shows reasonably good agreement with the experimental water permeability data.

Shaping single-walled metal oxide nanotubes from precursors of controlled curvature.

We demonstrate new molecular-level concepts for constructing nanoscopic metal oxide objects. First, the diameters of metal oxide nanotubes are shaped with angstrom-level precision by controlling the shape of nanometer-scale precursors. Second, we measure (at the molecular level) the subtle relationships between precursor shape and structure and final nanotube curvature. Anionic ligands are used to exert fine control over precursor shapes, allowing assembly into nanotubes whose diameters relate directly to the curvatures of the 'shaped' precursors.

Predicting Adult Pulmonary Ventilation Volume and Wearing Compliance by On-Board Accelerometry During Personal Level Exposure Assessments.

BACKGROUND: Metabolic functions typically increase with human activity, but optimal methods to characterize activity levels for real-time predictions of ventilation volume (l/min) during exposure assessments have not been available. Could tiny, triaxial accelerometers be incorporated into personal level monitors to define periods of acceptable wearing compliance, and allow the exposures (µg/m3) to be extended to potential doses in µg/min/kg of body weight? OBJECTIVES: In a pilot effort, we tested: 1) whether appropriately-processed accelerometer data could be utilized to predict compliance and in linear regressions to predict ventilation volumes in real time as an on-board component of personal level exposure sensor systems, and 2) whether locating the exposure monitors on the chest in the breathing zone, provided comparable accelerometric data to other locations more typically utilized (waist, thigh, wrist, etc.). METHODS: Prototype exposure monitors from RTI International and Columbia University were worn on the chest by a pilot cohort of adults while conducting an array of scripted activities (all <10 METS), spanning common recumbent, sedentary, and ambulatory activity categories. Referee Wocket accelerometers that were placed at various body locations allowed comparison with the chest-located exposure sensor accelerometers. An Oxycon Mobile mask was used to measure oral-nasal ventilation volumes in-situ. For the subset of participants with complete data (n= 22), linear regressions were constructed (processed accelerometric variable versus ventilation rate) for each participant and exposure monitor type, and Pearson correlations computed to compare across scenarios. RESULTS: Triaxial accelerometer data were demonstrated to be adequately sensitive indicators for predicting exposure monitor wearing compliance. Strong linear correlations (R values from 0.77 to 0.99) were observed for all participants for both exposure sensor accelerometer variables against ventilation volume for recumbent, sedentary, and ambulatory activities with MET values ~<6. The RTI monitors mean R value of 0.91 was slightly higher than the Columbia monitors mean of 0.86 due to utilizing a 20 Hz data rate instead of a slower 1 Hz rate. A nominal mean regression slope was computed for the RTI system across participants and showed a modest RSD of +/-36.6%. Comparison of the correlation values of the exposure monitors with the Wocket accelerometers at various body locations showed statistically identical regressions for all sensors at alternate hip, ankle, upper arm, thigh, and pocket locations, but not for the Wocket accelerometer located at the dominant-side wrist location (R=0.57; p=0.016). CONCLUSIONS: Even with a modest number of adult volunteers, the consistency and linearity of regression slopes for all subjects were very good with excellent within-person Pearson correlations for the accelerometer versus ventilation volume data. Computing accelerometric standard deviations allowed good sensitivity for compliance assessments even for sedentary activities. These pilot findings supported the hypothesis that a common linear regression is likely to be usable for a wider range of adults to predict ventilation volumes from accelerometry data over a range of low to moderate energy level activities. The predicted volumes would then allow real-time estimates of potential dose, enabling more robust panel studies. The poorer correlation in predicting ventilation rate for an accelerometer located on the wrist suggested that this location should not be considered for predictions of ventilation volume.

Control of microfluidic flow in amphiphilic fabrics.

Woven textile fabrics were designed and constructed from hydrophilic and hydrophobic spun yarns to give planar substrates containing amphiphilic microchannels with defined orientations and locations. Polypropylene fibers were spun to give hydrophobic yarns, and the hydrophilic yarns were spun from a poly(ethylene terephthalate) copolyester. Water wicking rates into the fabrics were measured by video microscopy from single drops, relevant for point-of-care microfluidic diagnostic devices, and from reservoirs. intra-yarn microchannels in the hydrophilic polyester yarns were shown to selectively transport aqueous fluids, with the flow path governed by the placement of the hydrophilic yarns in the fabric. By comparing fluid transport in fabric constructions with systematic variations in the numbers of adjacent parallel and orthogonal hydrophilic yarns, it was found that inter-yarn microchannels significantly increased wicking rates. Simultaneous wicking of an aqueous and hydrocarbon fluid into the hydrophilic and hydrophobic microchannels of an amphiphilic fabric was successfully demonstrated. The high degree of interfacial contact and micrometer-scale diffusion lengths of such coflowing immiscible fluid streams inside amphiphilic fabrics suggest potential applications as highly scalable and affordable microcontactors for liquid-liquid extractions.

Formation of single-walled aluminosilicate nanotubes from molecular precursors and curved nanoscale intermediates.

We report the identification and elucidation of the mechanistic role of molecular precursors and nanoscale (1-3 nm) intermediates with intrinsic curvature in the formation of single-walled aluminosilicate nanotubes. We characterize the structural and compositional evolution of molecular and nanoscale species over a length scale of 0.1-100 nm by electrospray ionization mass spectrometry, nuclear magnetic resonance spectroscopy ((27)Al liquid-state, (27)Al and (29)Si solid-state MAS), and dynamic light scattering. Together with structural optimization of key experimentally identified species by solvated density functional theory calculations, this study reveals the existence of intermediates with bonding environments, as well as intrinsic curvature, similar to the structure of the final nanotube product. We show that "proto-nanotube-like" intermediates with inherent curvature form in aqueous synthesis solutions immediately after initial hydrolysis of reactants, disappear from the solution upon heating to 95 °C due to condensation accompanied by an abrupt pH decrease, and finally form ordered single-walled aluminosilicate nanotubes. Detailed quantitative analysis of NMR and ESI-MS spectra from the relevant aluminosilicate, aluminate, and silicate solutions reveals the presence of a variety of monomeric and polymeric aluminate and aluminosilicate species (Al(1)Si(x)-Al(13)Si(x)), such as Keggin ions [AlO(4)Al(12)(OH)(24)(H(2)O)(12)](7+) and polynuclear species with a six-membered Al oxide ring unit. Our study also directly reveals the complexation of aluminate and aluminosilicate species with perchlorate species that most likely inhibit the formation of larger condensates or nontubular structures. Integration of all of our results leads to the construction of the first molecular-level mechanism of single-walled metal oxide nanotube formation, incorporating the role of monomeric and polymeric aluminosilicate species as well as larger nanoparticles.

Sorption isotherm measurements by NMR.

An experimental setup is described for the automated recording of sorption isotherms by NMR experiments at precisely defined levels of relative humidity (RH). Implementation is demonstrated for a cotton fabric; Bloch decays. T1 and T2* relaxation times were measured at predefined steps of increasing and decreasing relative humidities (RHs) so that a complete isotherm of NMR properties was obtained. Bloch decays were analyzed by fitting to relaxation functions consisting or a slow- and a fast-relaxing component. The fraction of slow-relaxing component was greater than the fraction of sorbed moisture determined from gravimetric sorption data. The excess slow-relaxing component was attributed to plasticized segments of the formerly rigid cellulose matrix. T1 and T2* sorption isotherms exhibit hysteresis similar to gravimetric sorption isotherms. However, correlating RH to moisture content (MC) reveals that both relaxation constants depend only on MC, and not on the history of moisture exposure.

CHAMPS physical activity questionnaire for older adults: outcomes for interventions.

PURPOSE: To evaluate effectively interventions to increase physical activity among older persons, reliable and valid measures of physical activity are required that can also detect the expected types of physical activity changes in this population. This paper describes a self-report physical activity questionnaire for older men and women, developed to evaluate the outcomes of the Community Healthy Activities Model Program for Seniors (CHAMPS), an intervention to increase physical activity. METHODS: The questionnaire assesses weekly frequency and duration of various physical activities typically undertaken by older adults. We estimated caloric expenditure/wk expended in physical activity and created a summary frequency/wk measure. We calculated measures of each of these for: 1) activities of at least moderate intensity (MET value >/= 3.0); and 2) all specified physical activities, including those of light intensity. Six-month stability was estimated on participants not likely to change (assessment-only control group, physically active cohort). Several tests of construct validity were conducted, and sensitivity to change was analyzed based on response to the CHAMPS intervention. RESULTS: The sample (N = 249) comprised underactive persons (N = 173 from the CHAMPS trial) and active persons (N = 76). The sample was aged 65-90 yr (mean = 74, SD = 6); 64% were women, and 9% were minorities. Six-month stability ranged from 0.58 to 0.67, using intraclass correlation coefficients. Nearly all construct validity hypotheses were confirmed, though correlations were modest. All measures were sensitive to change (P < or = 0.01), with small to moderate effect sizes (0.38-0.64). CONCLUSIONS: The CHAMPS measure may be useful for evaluating the effectiveness of programs aimed at increasing levels of physical activity in older adults.

What to look for in assessing responsiveness to exercise in a health context.

PURPOSE: When attempting to assess responsiveness to habitual exercise in a health context, there is a wide range of issues that need to be addressed in order to provide science-based recommendations for use in evidence-informed health care delivery. Issues regarding responsiveness include characteristics of the exercise regimen or dose as well as characteristics of the response or effect. RESULTS: The exercise dose typically has been characterized by its type, intensity, session duration, and session frequency with the concepts of activity profile, activity volume, and accumulation over multiple bouts throughout the day recently added to these discussions. When establishing the dose for a designated outcome, specificity of the response in relation to exercise type needs to be considered. Understanding the role of intensity as a stimulus for change is critical because of the intensity-related biological responses to exercise, its role in exercise-induce medical complications, and the aversion many adults have to vigorous exercise. Receiving considerable attention is whether a higher intensity or greater volume of endurance-type exercise is more important in producing a variety of health-related benefits. To understand the potential role of accumulation of exercise, more information is needed on benefits derived from very short (< or = 5 min) bouts of exercise performed frequently as well as very long bouts (> or = 90 min) performed infrequently. CONCLUSIONS: When considering the response, it is important to establish the priority health outcomes, the relationship of the dose response for individual biological variables to the dose response for clinical outcomes, the basis for substantial interindividual variations in the response to a specific exercise dose, and the health benefit to health risk relationship for various doses of exercise. Scientific resolution of these issues will substantially facilitate the development and dissemination of appropriate guidelines for the use of exercise in promoting health.

The effect of soy protein with or without isoflavones relative to milk protein on plasma lipids in hypercholesterolemic postmenopausal women.

BACKGROUND: Clinical trial data and the results of a meta-analysis suggest a hypocholesterolemic effect of soy protein. The effect may be partially attributable to the isoflavones in soy. Few studies have examined the separate effects of soy protein and isoflavones. OBJECTIVE: The objective of this study was to determine the effect of soy protein and isoflavones on plasma lipid concentrations in postmenopausal, moderately hypercholesterolemic women. DESIGN: This was a randomized, double-blind, placebo-controlled clinical trial with 3 treatment groups. After a 4-wk run-in phase during which the women consumed a milk protein supplement, the subjects were randomly assigned to 12 wk of dietary protein supplementation (42 g/d) with either a milk protein (Milk group) or 1 of 2 soy proteins containing either trace amounts of isoflavones (Soy- group) or 80 mg aglycone isoflavones (Soy+ group). RESULTS: LDL-cholesterol concentrations decreased more in the Soy+ group (n = 31) than in the Soy- group (n = 33) (0.38 compared with 0.09 mmol/L; P = 0.005), but neither of these changes was significantly different from the 0.26-mmol/L decrease observed in the Milk group (n = 30). The results for total cholesterol were similar to those for LDL cholesterol. There were no significant differences in HDL-cholesterol or triacylglycerol concentrations between the 3 groups. CONCLUSIONS: The difference in total- and LDL-cholesterol lowering between the 2 soy-protein supplements suggests an effect attributable to the isoflavone-containing fraction. However, the unexpected LDL-cholesterol lowering observed in the Milk group, and the fact that there was no significant difference between either soy group and the Milk group, suggests that changes may have been due to other factors related to participation in the study.

High-density lipoprotein cholesterol and vascular stiffness at baseline in the activity counseling trial.

In a middle-aged patient population, age was associated with stiffer vessels and high-density lipoprotein cholesterol with more elastic vessels. High-density lipoprotein cholesterol may be an indirect indicator of aerobic capacity or of less atherosclerosis, suggesting mechanisms for preserving vascular integrity.

Impact of a home-based walking and resistance training program on quality of life in patients with heart failure.

Patients with heart failure (HF) often have profound activity limitations and diminished quality of life (QOL) due to symptoms of dyspnea and fatigue. Although recent studies demonstrate positive physiologic and psychological benefits of low to moderate intensity, supervised, aerobic exercise training performed 3 to 5 days/ week for 20 to 40 minutes' duration, in a monitored setting, the efficacy of a home-based exercise program combining endurance and resistance exercise on symptoms and QOL, are unknown. This randomized controlled study examined the efficacy, safety, and adherence rates of a 3-month home-based combined walking and resistance exercise program on symptoms and QOL in 40 women and men aged 30 to 76 years with New York Heart Association class II to III HF. Baseline and 3-month evaluations consisted of a chronic HF questionnaire to assess symptoms and QOL and exercise capacity by symptom-limited treadmill exercise test with respiratory gas analysis. The exercise intervention improved fatigue (p = 0.02), emotional function (p = 0.01), and mastery (p = 0.04). Overall exercise adherence was excellent (90%) and there were no reported adverse events. A moderate intensity home-based combined walking and resistance program for patients with class II to III HF is safe and effective in reducing symptoms and improving QOL.

Compendium of physical activities: an update of activity codes and MET intensities.

We provide an updated version of the Compendium of Physical Activities, a coding scheme that classifies specific physical activity (PA) by rate of energy expenditure. It was developed to enhance the comparability of results across studies using self-reports of PA. The Compendium coding scheme links a five-digit code that describes physical activities by major headings (e.g., occupation, transportation, etc.) and specific activities within each major heading with its intensity, defined as the ratio of work metabolic rate to a standard resting metabolic rate (MET). Energy expenditure in MET-minutes, MET-hours, kcal, or kcal per kilogram body weight can be estimated for specific activities by type or MET intensity. Additions to the Compendium were obtained from studies describing daily PA patterns of adults and studies measuring the energy cost of specific physical activities in field settings. The updated version includes two new major headings of volunteer and religious activities, extends the number of specific activities from 477 to 605, and provides updated MET intensity levels for selected activities.