Femtosecond studies of the iodine–mesitylene charge‐transfer complex

Femtosecond laser studies have been performed to investigate the initial photodissociation reactions of I2–mesitylene charge transfer complexes. Photodissociation occurs along both the I2–mesitylene ‘‘bond’’ and the I–I bond with a branching ratio of 2:3 for the two reaction coordinates. Following excitation at 400 nm, geminate recombination occurs along both reaction coordinates. The reformed I2–mesitylene complexes are formed vibrationally hot and relax on a time scale of 13 ps. The I–mesitylene spectrum is fully developed within 500 fs of the pump pulse. Approximately 40% of the I–mesitylene complexes undergo geminate recombination on a time scale of 14 ps. Most of the remaining complexes recombine with their original partners on a time scale of 400 ps. The initial anisotropy of the photoproduct absorption is 0.09±0.02. This low anisotropy is a direct result of the geometry of the complex and nature of the electronic transition rather than indicative of ultrafast motion toward an asymmetric transition state preceding dissociation. © 1995 American Institute of Physics.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/70671/2/JCPSA6-103-18-7877-1.pd

Effectiveness of tailored lifestyle interventions, using web-based and print-mail, for reducing blood pressure among rural women with prehypertension: main results of the Wellness for Women: DASHing towards Health clinical trial.

Background Lifestyle modification is recommended for management of prehypertension, yet finding effective interventions to reach rural women is a public health challenge. This community-based clinical trial compared the effectiveness of standard advice to two multi-component theory-based tailored interventions, using web-based or print-mailed delivery, in reducing blood pressure among rural women, ages 40–69, with prehypertension. Methods 289 women with prehypertension enrolled in the Wellness for Women: DASHing towards Health trial, a 12-month intervention with 12-month follow-up. Women were randomly assigned to groups using a 1:2:2 ratio, comparing standard advice (30-minute counseling session) to two interventions (two 2-hour counseling sessions, 5 phone goal-setting sessions, strength-training video, and 16 tailored newsletters, web-based or print-mailed). Linear mixed model methods were used to test planned pairwise comparisons of marginal mean change in blood pressure, healthy eating and activity, adjusted for age and baseline level. General estimating equations were used to examine the proportion of women achieving normotensive status and meeting health outcome criteria for eating and activity. Results Mean blood pressure reduction ranged from 3.8 (SD = 9.8) mm Hg to 8.1 (SD = 10.4) mm Hg. The 24-month estimated marginal proportions of women achieving normotensive status were 47% for web-based, and 39% for both print-mailed and standard advice groups, with no group differences (p = .11 and p = .09, respectively). Web-based and print-mailed groups improved more than standard advice group for waist circumference (p = .017 and p = .016, respectively); % daily calories from fat (p = .018 and p = .030) and saturated fat (p = .049 and p = .013); daily servings of fruit and vegetables (p = .008 and p \u3c .005); and low fat dairy (p \u3c .001 and p = .002). Greater improvements were observed in web-based versus standard advice groups in systolic blood pressure (p = .048) and estimated VO2max (p = .037). Dropout rates were 6% by 6-months, 11.4% by 24 months, with no differences across groups. Conclusions Rural women with prehypertension receiving distance-delivery theory-based lifestyle modifications can achieve a reduction of blood pressure and attainment of normotensive status

User Engagement Associated with Web-Intervention Features to Attain Clinically Meaningful Weight Loss and Weight Maintenance in Rural Women

Objective: Purely web-based weight loss and weight-loss maintenance interventions show promise to influence behavior change. Yet, little is known about user engagement with features of web-based interventions that predict clinically meaningful weight loss (≥5% bodyweight loss). This study examines level of website feature engagement with the likelihood of attaining ≥5% bodyweight loss after 6 and 18 months participation in a web-based intervention, among rural women at high risk of obesity-related diseases and disability. Methods: In this secondary analysis of clinical trial data of 201 rural women, we examined weight change and user engagement, measured as clicks on specific web-based intervention features (messaging and self-tracking), as associated with clinically meaningful weight loss (baseline to 6 months) and weight-loss maintenance (6 to 18 months). Results: Generalized estimating equations, adjusted for age, intervention group, and intervention phase, revealed high engagement with messaging predicted whether women achieved ≥5% weight loss at 6 months and at 18 months. There was no effect of self-tracking. Conclusions: Being engaged with messages was associated with attaining clinically meaningful short-term and longer-term weight loss. This trial is registered with NCT01307644

The ultrafast ground and excited state dynamics of cis-hexatriene in cyclohexane

One- and two-color kinetics have been combined with broadband ultraviolet transient absorption spectroscopy in the 265–300 nm region to elucidate the photophysics of cis-hexatriene in cyclohexane solvent. The lowest singlet excited state, the 2 1A121A1 state, is observed to have a lifetime of 200±50 fs. The ground-state hexatriene is produced vibrationally hot. The excess vibrational energy permits ultrafast isomerization around the C–C single bonds in hexatriene. This results in a dynamic equilibrium of the three cis-hexatriene rotamers, which then relaxes multiexponentially to the room-temperature distribution in which the di-s-trans-Z-hexatriene form predominates. The peak of the mono-s-trans (cZt-HT) population is estimated to be ∼50%. Vibrational cooling results in trapping of a small amount, ∼8%, of cZt-HT that relaxes on a much longer time scale as the barrier to isomerization becomes important. An estimate of the absorption spectrum of cZt-HT is deduced from analysis of the spectral data at 50 ps. © 1997 American Institute of Physics.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/70051/2/JCPSA6-107-13-4985-1.pd

The ultrafast photochemical ring-opening reaction of 1,3-cyclohexadiene in cyclohexane

The ring-opening reaction of 1,3-cyclohexadiene in cyclohexane solution and the subsequent photoproduct cooling dynamics have been investigated by using two-color transient absorption kinetic measurements and novel time-resolved absorption spectroscopy in the 260–300 nm spectral region. The initial photoproduct in this reaction, s-cis,Z,s-cis-1,3,5-hexatrienes-cis,Z,s-cis-1,3,5-hexatriene (cZc-HT) is formed on a ∼ 250 fs∼250fs time scale. Spectra deduced for time delays very close to zero, as well as calculated Rice–Ramsperger–Kassel–Marcus unimolecular reaction rates, provide strong evidence that the quantum yield for the reaction is determined before any relaxation occurs on the ground state. Upon formation, the vibrationally excited hexatriene photoproduct is able to isomerize around C–C single bonds freely. As a result, the evolution observed in the transient absorption measurements represents a combination of rotamer population dynamics and thermalization due to energy transfer to the solvent. Three distinct time scales for relaxation are observed. These time scales correspond approximately to the development of an evolving equilibrium of Z-HT rotamers (1–5 ps), vibrational cooling and thermal equilibration with the surroundings (10–20 ps), and activated isomerization of trapped cZt-HT to tZt-HT (≫100 ps).(≫100ps). © 1998 American Institute of Physics.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/70793/2/JCPSA6-108-2-556-1.pd

Associations of cardiorespiratory fitness and fatness with metabolic syndrome in rural women with prehypertension.

BACKGROUND: This study investigated the associations of fitness and fatness with metabolic syndrome in rural women, part of a recognized US health disparities group. METHODS: Fitness, percentage body fat, BMI, and metabolic syndrome criteria were assessed at baseline in 289 rural women with prehypertension, ages 40-69, enrolled in a healthy eating and activity community-based clinical trial for reducing blood pressure. RESULTS: Ninety (31%) women had metabolic syndrome, of which 70% were obese by BMI (≥30 kg/m²), 100% by percentage body fat (≥30%), and 100% by revised BMI standards (≥25 kg/m²) cited in current literature. Hierarchical logistic regression models, adjusted for age, income, and education, revealed that higher percentage body fat (P \u3c 0.001) was associated with greater prevalence of metabolic syndrome. Alone, higher fitness lowered the odds of metabolic syndrome by 7% (P \u3c 0.001), but it did not lower the odds significantly beyond the effects of body fat. When dichotomized into fit and unfit groups, women categorized as fat had lower odds of metabolic syndrome if they were fit by 75% and 59%, for percentage body fat and revised BMI, respectively. CONCLUSION: Among rural women with prehypertension, obesity and fitness were associated with metabolic syndrome. Obesity defined as ≥25 kg/m² produced results more consistent with percentage body fat as compared to the ≥30 kg/m² definition

Associations of Cardiorespiratory Fitness and Fatness with Metabolic Syndrome in Rural Women with Prehypertension

This study investigated the associations of fitness and fatness with metabolic syndrome in rural women, part of a recognized US health disparities group. Methods. Fitness, percentage body fat, BMI, and metabolic syndrome criteria were assessed at baseline in 289 rural women with prehypertension, ages 40–69, enrolled in a healthy eating and activity communitybased clinical trial for reducing blood pressure. Results. Ninety (31%) women had metabolic syndrome, of which 70% were obese by BMI (≥30 kg/m2), 100% by percentage body fat (≥30%), and 100% by revised BMI standards (≥25 kg/m2) cited in current literature. Hierarchical logistic regression models, adjusted for age, income, and education, revealed that higher percentage body fat (P \u3c 0.001) was associated with greater prevalence of metabolic syndrome. Alone, higher fitness lowered the odds of metabolic syndrome by 7% (P \u3c 0.001), but it did not lower the odds significantly beyond the effects of body fat. When dichotomized into “fit” and “unfit” groups, women categorized as “fat” had lower odds of metabolic syndrome if they were “fit” by 75% and 59%, for percentage body fat and revised BMI, respectively. Conclusion. Among rural women with prehypertension, obesity and fitness were associated with metabolic syndrome. Obesity defined as ≥25 kg/m2 produced results more consistent with percentage body fat as compared to the ≥30 kg/m2 definition

Erratum to ‘‘Associations of Cardiorespiratory Fitness and Fatness with Metabolic Syndrome in Rural Women with Prehypertension’’

In the original paper, the authors discovered a computer coding error that resulted in 33 of the women’s ages being incorrectly recorded. All analyses were repeated for this paper using the corrected age dataset, as all our logistic regression analyses in the published paper were adjusted for age.The repeated analyses, using the corrected dataset, lead to minor changes that needed to be reported to the results in the published paper. These corrections did not change the conclusion of the published paper.The authors apologize for any inconvenience

Associations of Cardiorespiratory Fitness and Fatness with Metabolic Syndrome in RuralWomen with Prehypertension

This study investigated the associations of fitness and fatness with metabolic syndrome in rural women, part of a recognized US health disparities group. Methods. Fitness, percentage body fat, BMI, and metabolic syndrome criteria were assessed at baseline in 289 rural women with prehypertension, ages 40–69, enrolled in a healthy eating and activity communitybased clinical trial for reducing blood pressure. Results. Ninety (31%) women had metabolic syndrome, of which 70% were obese by BMI (≥30 kg/m2), 100% by percentage body fat (≥30%), and 100% by revised BMI standards (≥25 kg/m2) cited in current literature. Hierarchical logistic regression models, adjusted for age, income, and education, revealed that higher percentage body fat (P \u3c 0.001) was associated with greater prevalence of metabolic syndrome. Alone, higher fitness lowered the odds of metabolic syndrome by 7% (P \u3c 0.001), but it did not lower the odds significantly beyond the effects of body fat. When dichotomized into “fit” and “unfit” groups, women categorized as “fat” had lower odds of metabolic syndrome if they were “fit” by 75% and 59%, for percentage body fat and revised BMI, respectively. Conclusion. Among rural women with prehypertension, obesity and fitness were associated with metabolic syndrome. Obesity defined as ≥25 kg/m2 produced results more consistent with percentage body fat as compared to the ≥30 kg/m2 definition

Obesity and Physical Function in Rural Women who enroll in a Lifestyle Modification Intervention for Reducing Blood Pressure

Purpose: Rural women have high prevalence of obesity and prehypertension. Obesity, if associated with poor physical function, may have implications for applying activity guidelines for women volunteering for lifestyle modification. This study examined associations of body mass index (BMI) and percent body fat with measures of 1-mile walk time, post-walk perceived exertion, and 10-repetition chair stands in rural women ages 40-69. Methods: Cross-sectional baseline data were collected using standardized methods from 289 rural women with prehypertension who volunteered for a lifestyle clinical trial for reducing blood pressure. ANOVAs and linear regression were used for analysis. Results: With exception of the chair stands measure across categories of BMI, group differences were noted in all measures across categories of BMI and percent body fat, with women in the two highest categories demonstrating the poorest performance. These two body composition measures were significant predictors for 1-mile walk-time and 10-repetition chair stands, after controlling for confounding variables. Conclusions: Poorer scores were observed in performance-based measures in women with higher BMI and percent body fat, though mean scores were above thresholds for functional limitation. Physical performance needs to be assessed and addressed by physical therapists when providing lifestyle interventions for overweight and obese women