Occupational Exposure to Solar UVB and Seasonal Monitoring of Serum Levels of 25-hydroxy Vitamin D3: A Case–Control Study

To characterize the relationship between occupational sun exposure and seasonal variations in serum 25-OH-D3, four consecutive measurements of 25-OH-D3, one per season, were taken in 122 outdoor and 104 indoor Israeli workers. Continuous UVB measurements, taken in Beer Sheva, Israel, provided the average daily standard erythema dose (SED) of ambient solar UVB. The average daily exposure of the outdoor and indoor workers to solar UVB was 4.4 ± 1.6 h (4.0–37.6 SED) and 0.9 ± 0.5 h (0.6–8.2 SED), respectively. At each season mean 25-OH-D3 were significantly higher among outdoor workers than among indoor workers. Mean 25-OH-D3 increased significantly from spring to autumn in both gender and occupational groups. Adjusting for confounders, high (>median) 25-OH-D3 among males was significantly associated with occupational sun exposure in the autumn (odds ratio [OR] 4.31; 95% confidence interval [CI] 1.4–13.3), and among females in the spring (OR 3.35; 95% CI 1.53–7.32). Among this working population optimal vitamin D status (≥30 ng mL⁻¹) was approached only in summer by males working either outdoor or indoor. In the rest of the year 25-OH-D3 ranged between ≥20.0 and 29.0 ng mL⁻¹. Monitoring 25-OH-D3 may disclose undesirable vitamin D status following reduced sun exposure for skin cancer prevention among outdoor workers.     

Validation of Brief Questionnaire Measures of Sun Exposure and Skin Pigmentation Against Detailed and Objective Measures Including Vitamin D Status

Self‐reported sun exposure is commonly used in research, but how well this represents actual sun exposure is poorly understood. From February to July 2011, a volunteer sample (n = 47) of older adults (≥45 years) in Canberra, Australia, answered brief questions on time outdoors (weekdays and weekends) and natural skin color. They subsequently maintained a sun diary and wore an ultraviolet radiation (UVR) digital dosimeter for 7 days. Melanin density was estimated using reflectance spectrophotometry; lifetime sun damage was assessed using silicone casts of the back of the hand; and serum 25‐hydroxyvitamin D (25(OH)D) concentration was assayed. Questionnaire‐reported time outdoors correlated significantly with diary‐recorded time outdoors (Spearman correlation r_s = 0.66; 95% CI 0.46, 0.80; P < 0.001) and UVR dosimeter dose (r_s = 0.46; 95% CI 0.18, 0.68; P = 0.003), but not 25(OH)D concentration (r_s = 0.24; 95% CI ?0.05, 0.50; P = 0.10). Questionnaire‐reported untanned skin color correlated significantly with measured melanin density at the inner upper arm (r_s = 0.49; 95% CI 0.24, 0.68; P < 0.001). In a multiple linear regression model, statistically significant predictors of 25(OH)D concentration were self‐reported frequency of physical activity, skin color and recent osteoporosis treatment (R² = 0.54). In this study, brief questionnaire items provided valid rankings of sun exposure and skin color, and enabled the development of a predictive model for 25(OH)D concentration.     

Personal Sun Exposure and Serum 25‐hydroxy Vitamin D Concentrations

Solar ultraviolet‐B radiation (UVB) is essential for epidermal vitamin D production. We aimed to quantitate the relationship between personal solar UV exposure and serum 25hydroxy vitamin D (25[OH]D) concentration. Blood was collected for 25(OH)D analysis in 207 South Australian adults aged 27–61 years. At the time of blood collection, each participant completed a questionnaire, which included a calendar for recall of sun exposure in the preceding 16 weeks. We examined the association between solar UV exposure and serum 25(OH)D graphically from smoothed scatter plots, and modeled it using multiple linear regression, with age, sex and body mass index as covariates. Estimated erythemal solar UV exposure in the 6 weeks before blood collection best predicted serum 25(OH)D concentrations. Serum 25(OH)D rose with increasing personal solar UV exposure to a maximum of about 89 nmol L^?1 at an estimated mean weekly solar erythemal UV exposure of about 1230 mJ cm^?2. The maximum was the same after accounting for clothing coverage and was reached at an estimated whole body equivalent exposure to ambient UV of ca 700 mJ cm^?2. These results suggest that an average maximum serum 25(OH)D of ca 89 nmol L^?1 is achieved from sun exposure in a healthy Australian adult population.     

Effect of A Sun Protection Intervention on the Immune Response to Measles Booster Vaccination in Infants in Rural South Africa

The incidence of many serious childhood infections can be reduced by vaccination. High sun exposure at the time of vaccination has been associated with a reduced antigen‐specific immune response. We hypothesized that providing sun protection advice and equipment to mothers of children who were waiting to be vaccinated would result in a more robust immunization response. We conducted a pilot study in 2015/2016 (data analyzed in 2017–2018) among 98 Black African children (~18 months of age) receiving the booster measles vaccination at two clinics in South Africa. Clinics were randomized to receive (or not) sun protection advice and equipment. We recorded demographic information on children and mothers and data on the child's usual sun exposure. At approximately 4 weeks’ postmeasles vaccination, we measured measles immunoglobulin G levels in children. All children with blood results (n = 87, 89%) across both groups had antibody titers higher than 200 mIU mL^?1 which was considered the protective antibody concentration. There was no statistically significant difference in titers between groups: geometric difference in mean titers 1.13 mIU mL^?1 (95% CI 0.85, 1.51; P = 0.39) and 1.38 mIU mL^?1 (95% CI 0.90, 2.11, P = 0.14) for unadjusted and adjusted analyses, respectively. This study demonstrated that a sun protection intervention study could be performed in a developing‐world pediatric vaccination setting. Although the sun protection intervention around the time of vaccination was not associated with a higher antibody level, given the potential importance of such an effect, a larger study should be considered.     

Vitamin D status and its associated factors of free living Malay adults in a tropical country, Malaysia

Vitamin D status is influenced by sun exposure, geographic latitude, daily outdoor activities, body surface exposed to sunlight and dietary intakes. Malaysia, is sunny all year round. However, the vitamin D status of this population especially among the healthy and free living adults is not known. Therefore a study of vitamin D status and associated factors was initiated among an existing Malay cohort in Kuala Lumpur. A total of 380 subjects were sampled to have their vitamin D status assessed using 25-hydroxyvitamin D (25(OH)D). A short questionnaire enquiring socio-demographic characteristics, exposure to sunlight and clothing style was administered. Their mean age was 48.5±5.2years and the mean 25(OH)D for males and females were 56.2±18.9nmol/L and 36.2±13.4nmol/L respectively. There were significant positive correlation for sun exposure score (r=0.27, p<0.001) and negative correlation for sun protection score (r=-0.41, p<0.001) with 25(OH)D levels. In the logistic regression model, females (OR=2.93; 95% CI: 1.17, 7.31), BMI (1.1; 1.03, 1.20) and sun exposure score (0.998; 0.996, 0.999) were significantly associated with vitamin D status as represented by 25(OH)D levels. Our findings show that obesity, lifestyle behaviours and clothing style are directly associated with our participants especially females' low vitamin D status.     

Sun Exposure and Vitamin D Status as Northeast Asian Migrants Become Acculturated to Life in Australia

Vitamin D deficiency is more common in Northeast‐Asian immigrants to western countries than in the local population; prevalence equalizes as immigrants adopt the host country's culture. In a community‐based study of 100 Northeast‐Asian immigrants in Canberra, Australia, we examined predictors of vitamin D status, its association with indicators of acculturation (English language use; time since migration) and mediators of that association. Participants completed a sun and physical activity diary and wore an electronic ultraviolet radiation (UVR) dosimeter for 7 days. Skin colour was measured by reflectance spectrophotometry. Serum concentrations of 25‐hydroxyvitamin D (25(OH)D) and cardio‐metabolic biomarkers were measured on fasting blood. In a multiple linear regression model, predictors for 25(OH)D concentration were season of blood collection, vitamin D supplementation, UVR exposure, body mass index, physical activity and having private health insurance (R² = 0.57). Greater acculturation was associated with lower risk of vitamin D deficiency (de‐seasonalized 25(OH)D level <50 nmol L^?1) (Adjusted Odds Ratio (AOR): 0.22 [95%CI 0.04–0.96]); this association was statistically mediated by physical activity and time outdoors. Vitamin D deficiency was associated with higher total cholesterol levels (>5.0 mmol L^?1) (AOR: 7.48 [95%CI 1.51–37.0]). Targeted public health approaches are required to manage the high prevalence of vitamin D deficiency in migrants retaining a traditional lifestyle.     

Sunshine is an Important Determinant of Vitamin D Status Even Among High‐dose Supplement Users: Secondary Analysis of a Randomized Controlled Trial in Crohn's Disease Patients

Sunshine is considered to be the most important source of vitamin D. Due to an increased risk of skin cancer, sun avoidance is advised, but this directly contributes to the high prevalence of vitamin D deficiency. The simple solution is to advise vitamin D supplementation. The aim of this study was to examine the absolute and relative contribution of sunshine and supplementation to vitamin status. This study was a secondary analysis of an RCT of 92 Crohn's disease patients in remission (49% female, median age = 44). Participants were randomized to 2000 IU day^?1 of vitamin D3 or placebo for 1 year, with 25‐hydroxyvitamin D (25(OH)D) being measured at baseline and every 4 months. Based on participant's place of residence, daily ambient UVB dose at wavelengths that can induce vitamin D synthesis (D‐UVB) was obtained. Cumulative and weighted ambient D‐UVB (cw‐D‐UVB) exposure prior to each blood draw was calculated for each participant. Linear regression analysis and multilevel modeling were used to examine the association between UVB exposure, supplementation and 25(OH)D concentration. There was considerable annual variation in D‐UVB, cw‐D‐UVB and 25(OH)D. Both supplementation and cw‐D‐UVB were found to be strongly associated with 25(OH)D: in multilevel model, an increase of approximately 6 nmol L^?1 for every 100 kJ m^?2 in cw‐D‐UVB was found, among those receiving placebo and supplementation (P < 0.0001). Treatment was associated with increase of 23 nmol L^?1 (P < 0.0001). Sunshine is an important determinant of 25(OH)D concentration, even in those who are taking high‐dose vitamin D supplements and reside at a higher mid‐latitude location.     

Solvent‐Vapor‐Induced Reversible Single‐Crystal‐to‐Single‐Crystal Transformation of a Triphosphaazatriangulene‐Based Metal–Organic Framework

A triphosphaazatriangulene (H₃L) was synthesized through an intramolecular triple phospha‐Friedel–Crafts reaction. The H₃L triangulene contains three phosphinate groups and an extended π‐conjugated framework, which enables the stimuli‐responsive reversible transformation of [Cu(HL)(DMSO)?(MeOH)]_n, a 3D‐MOF that exhibits reversible sorption characteristics, into (H₃L?0.5 [Cu₂(OH)₄?6 H₂O] ?4 H₂O), a 1D‐columnar assembled proton‐conducting material. The hydrophilic nature of the latter resulted in a proton conductivity of 5.5×10^?3 S cm^?1 at 95 % relative humidity and 60 °C.     

Vitamin D status of adults from tropical Australia determined using two different laboratory assays: implications for public health messages

We measured serum 25 hydroxyvitamin D [25(OH)D] levels of ambulatory adults in tropical Australia to determine whether it is appropriate to continue promoting sun‐safety in this population. In August 2006 (winter), self‐administered questionnaires were completed by 145 Meals‐on‐Wheels volunteers (49.3% male; mean age 57.8 ± 14.7 years; 76.6% response) from Townsville, Queensland (Latitude 19^oS). Serum 25(OH)D was analyzed using two common assays. Mean levels were 68.3 (SD ± 18.7; range 26–142) by DiaSorin Radioimmunoassay and 83.0 (SD ± 30.8; range 30–184) by DiaSorin Liaison^® one. No participants were 25(OH)D deficient (<25 nmol L⁻¹). Nine participants (6.2%) had 25(OH)D levels between 25 and 50 nmol L⁻¹ (insufficient), by both methods (seven with a BMI ≥ 25). Twenty‐eight participants (19.3%) had one result in the insufficient range and the other in the adequate range. Thus, almost all of these free‐living adults in tropical Australia had adequate vitamin D levels at the end of winter. There was poor agreement between the two 25(OH)D assays. These results suggest it is appropriate to continue promoting sun‐safe messages to the ambulatory Caucasian adult population of North Queensland, which has an extremely high incidence of skin cancer. The lack of agreement between the two assays is a concern. Few doctors are aware of this measurement issue.     

Preparation of Protected β2‐ and β3‐Homocysteine, β2‐ and β3‐Homohistidine,and β2‐Homoserine for Solid‐Phase Syntheses

The Ser, Cys, and His side chains play decisive roles in the syntheses, structures, and functions of proteins and enzymes. For our structural and biomedical investigations of β‐peptides consisting of amino acids with proteinogenic side chains, we needed to have reliable preparative access to the title compounds. The two β³‐homoamino acid derivatives were obtained by Arndt–Eistert methodology from Boc‐His(Ts)‐OH and Fmoc‐Cys(PMB)‐OH (Schemes 2–4), with the side‐chain functional groups' reactivities requiring special precautions. The β²‐homoamino acids were prepared with the help of the chiral oxazolidinone auxiliary DIOZ by diastereoselective aldol additions of suitable Ti‐enolates to formaldehyde (generated in situ from trioxane) and subsequent functional‐group manipulations. These include OH→O^tBu etherification (for β²hSer; Schemes 5 and 6), OH→STrt replacement (for β²hCys; Scheme 7), and CH₂OH→CH₂N₃→CH₂NH₂ transformations (for β²hHis; Schemes 9–11). Including protection/deprotection/re‐protection reactions, it takes up to ten steps to obtain the enantiomerically pure target compounds from commercial precursors. Unsuccessful approaches, pitfalls, and optimization procedures are also discussed. The final products and the intermediate compounds are fully characterized by retention times (t_R), melting points, optical rotations, HPLC on chiral columns, IR, ¹H‐ and ¹³C‐NMR spectroscopy, mass spectrometry, elemental analyses, and (in some cases) by X‐ray crystal‐structure analysis.     

Rate constants of the gas‐phase reactions of OH radicals with trans‐2‐hexenal,trans‐2‐octenal,and trans‐2‐nonenal

The rate constants of the gas‐phase reaction of OH radicals with trans‐2‐hexenal, trans‐2‐octenal, and trans‐2‐nonenal were determined at 298 ± 2 K and atmospheric pressure using the relative rate technique. Two reference compounds were selected for each rate constant determination. The relative rates of OH + trans‐2‐hexenal versus OH + 2‐methyl‐2‐butene and β‐pinene were 0.452 ± 0.054 and 0.530 ± 0.036, respectively. These results yielded an average rate constant for OH + trans‐2‐hexenal of (39.3 ± 1.7) × 10^?12 cm³ molecule^?1 s^?1. The relative rates of OH+trans‐2‐octenal versus the OH reaction with butanal and β‐pinene were 1.65 ± 0.08 and 0.527 ± 0.032, yielding an average rate constant for OH + trans‐2‐octenal of (40.5 ± 2.5) × 10^?12 cm³ molecule^?1 s^?1. The relative rates of OH+trans‐2‐nonenal versus OH+ butanal and OH + trans‐2‐hexenal were 1.77 ± 0.08 and 1.09 ± 0.06, resulting in an average rate constant for OH + trans‐2‐nonenal of (43.5 ± 3.0) × 10^?12 cm³ molecule^?1 s^?1. In all cases, the errors represent 2σ (95% confidential level) and the calculated rate constants do not include the error associated with the rate constant of the OH reaction with the reference compounds. The rate constants for the hydroxyl radical reactions of a series of trans‐2‐aldehydes were compared with the values estimated using the structure activity relationship. © 2009 Wiley Periodicals, Inc. Int J Chem Kinet 41: 483–489, 2009     

Ultraviolet Index and Location are Important Determinants of Vitamin D Status in People with Human Immunodeficiency Virus

This study aimed to document the vitamin D status of HIV‐infected individuals across a wide latitude range in one country and to examine associated risk factors for low vitamin D. Using data from patients attending four HIV specialist clinics across a wide latitude range in Australia, we constructed logistic regression models to investigate risk factors associated with 25(OH)D < 75 nmol L^?1. 1788 patients were included; 87% were male, 76% Caucasian and 72% on antiretroviral therapy. The proportion with 25(OH)D < 50 nmol L^?1 was 27%, and <75 nmol L^?1 was 54%. Living in Melbourne compared with Cairns (adjusted odds ratio (aOR) 3.30; 95% CI 2.18, 4.99, P < 0.001) and non‐Caucasian origin (aOR 2.82, 95% CI 2.12, 3.75, P < 0.001) was associated with an increased risk, while extreme UV index compared with low UV index was associated with a reduced risk (aOR 0.33; 95% CI 0.20, 0.55, P < 0.001) of 25(OH)D < 75 nmol L^?1. In those with biochemistry available (n = 1117), antiretroviral therapy was associated with 25(OH)D < 75 nmol L^?1; however, this association was modified by serum cholesterol status. Location and UV index were the strongest factors associated with 25(OH)D < 75 nmol L^?1. Cholesterol, the product of an alternative steroid pathway with a common precursor steroid, modified the effect of antiretroviral therapy on serum 25(OH)D.     

Design,Synthesis and Biological Evaluation of Novel N‐(4‐([2,2′:5′,2′′‐Terthiophen]‐5‐yl)‐2‐methylbut‐3‐yn‐2‐yl) Benzamide Derivatives

On the basis of the principle of combination of active groups, a series of novel N‐(4‐([2,2′:5′,2′′‐terthiophen]‐5‐yl)‐2‐methylbut‐3‐yn‐2‐yl) benzamide derivatives were designed, synthesized and systematically evaluated for their antiviral activity against tobacco mosaic virus (TMV). The bioassay results showed that most of these compounds displayed good anti‐TMV activity, and some of them exhibited higher antiviral activity than commercial Ningnanmycin. Especially, compound 8e with excellent anti‐TMV activity (inactivation activity, 92.3%/500 µg·mL^?1; curative activity, 85.7%/500 µg·mL^?1 and protection activity, 64.7%/500 µg·mL^?1) emerged as a potential inhibitor of plant virus TMV. Quantitative structure‐activity relationship studies proved that the van der Waals volume (V) and electronic parameter (∑(∑σ_o+σ_p) and ∑σ_m) for the substituent R¹ were very important for antiviral activities in this class of compounds.     

Synthesis of the Anticodon Hairpin tRNAfMet Containing N‐{[9‐(β‐D‐Ribofuranosyl)‐9H‐purin‐6‐yl]carbamoyl}‐L‐threonine (=N6‐{{[(1S,2R)‐1‐Carboxy‐2‐hydroxypropyl]amino}carbonyl}adenosine,t6A)

As part of our studies on the structure of yeast ^tRNA_f^Met, we investigated the incorporation of N‐{[9‐(β‐D ‐ribofuranosyl)‐9H‐purin‐6‐yl]carbamoyl}‐L ‐threonine (t⁶A) in the loop of a RNA 17‐mer hairpin. The carboxylic function of the L ‐threonine moiety of t⁶A was protected with a 2‐(4‐nitrophenyl)ethyl group, and a (tert‐butyl)dimethylsilyl group was used for the protection of its secondary OH group. The 2′‐OH function of the standard ribonucleotide building blocks was protected with a [(triisopropylsilyl)oxy]methyl group. Removal of the base‐labile protecting groups of the final RNA with 1,8‐diazabicyclo[5.4.0]undec‐7‐ene (DBU) and then with MeNH₂ was done under carefully controlled conditions to prevent hydrolysis of the carbamate function, leading to loss of the L ‐threonine moiety.     

Mixed Boron(III) and Phosphorous(V) Complexes of meso‐Triaryl 25‐Oxasmaragdyrins

Two unprecedented mixed B^III/P^V complexes of meso‐triaryl 25‐oxasmaragdyrins were synthesized in appreciable yields under mild reaction conditions. These unusual 25‐oxasmaragdyrin complexes containing one or two seven‐membered heterocyclic rings comprised of five different atoms (B, C, N, O, and P) were prepared by reacting B(OH)(Ph)‐smaragdyrin and B(OH)₂‐smaragdyrin complexes, respectively, with POCl₃ in toluene at reflux temperature. The products were characterized by HRMS and 1D‐ and 2D‐NMR spectroscopy. X‐ray crystallography of one of the mixed B^III/P^V smaragdyrin complexes indicated that the macrocycle is significantly distorted and contains a stable seven‐membered heterocyclic ring within the macrocycle. The bands in the absorption and emission spectra were bathochromically shifted with reduced quantum yields and singlet‐state lifetimes relative to the free base, meso‐triaryl 25‐oxasmaragdyrin. The mixed B^III/P^V complexes were difficult to oxidize but easier to reduce than the free base. The DFT‐optimized structure of the 25‐oxasmaragdyrin complex with two seven‐membered heterocycles indicated that it was a bicyclic spiro compound with two half‐chair‐like conformers. This was in contrast to the chair‐like conformation of the complex with a single seven‐membered heterocyclic ring. Moreover, incorporation of a second phosphate group in the former case stabilized the bonding geometry and resulted in higher stability, which was reflected in the bathochromic shift of the absorption spectra, more‐positive oxidation potential, and less‐negative reduction potential.     

A poly (4‐vinylpridine‐co‐ethylene glycol dimethacrylate) monolithic concentrator for in‐line concentration‐capillary electrophoresis analysis of phenols in water samples

A poly(4‐vinylpridine‐co‐ethylene glycol dimethacrylate) monolith was synthesized in a capillary and constructed as a concentrator for the in‐line polymeric monolith microextraction coupling with capillary electrophoresis. The integrated system was then used for the simultaneous determination of five trace phenols (2‐nitrophenol, 3‐nitrophenol, 4‐nitrophenol, 2‐chlorophenol, and 2,4‐dichlorophenol) in water samples. The experimental parameters for in‐line solid‐phase extraction, such as composition and volume of the elution plug, pH of sample solution, and the time for sample loading were optimized. The sensitivity for the mixture of phenols (2‐nitrophenol, 3‐nitrophenol, 4‐nitrophenol, 2‐chlorophenol, and 2,4‐dichlorophenol) enhanced to 615–2222 folds at the optimum condition was compared to the sensitivity for a normal hydrodynamic injection in capillary electrophoresis. Linearity ranged from concentration of 10–500 ng mL^?1(R² > 0.999) for all five phenols with the detection limits of 1.3–3.3 ng mL^?1. In tap, snow and Yangtze River water spiked with 20 ng mL^?1 and 200 ng mL^?1, respectively, the recoveries of 84–105% were obtained. It has been demonstrated that this work has great potential for the analysis of phenols in genuine water samples.     

14‐Membered Cyclopeptides from Paliurus ramosissimus and P. hemsleyanus

Six 14‐membered cyclopeptide alkaloids, i.e., ramosines A–C, mucronine J, and lotusines A and D, were isolated from the roots of Paliurus ramosissimus, and an additional four, hemsines A–D, from the roots of P. hemsleyanus. Among these, ramosines A–C ( 1, 5 , and 6 , resp.) and hemsines A and B ( 7 and 8 , resp.) are new bases of the amphibine‐B type, and hemsines C and D ( 9 and 10 , resp.) are new integerrine‐type alkaloids. Additionally, ramosine C ( 6 ) represents the first 14‐membered cyclopeptide alkaloid possessing a substitution (? OH) at C(13′). Their structural elucidations were based on spectral analysis and molecular‐modeling studies. Pronounced solvent effects in the ¹H‐ and ¹³C‐NMR spectra of these two types of alkaloids were observed.     

Kinetics of the reactions of OH with 3‐methyl‐2‐cyclohexen‐1‐one and 3,5,5‐trimethyl‐2‐cyclohexen‐1‐one under simulated atmospheric conditions

Relative rate coefficients for the reactions of OH with 3‐methyl‐2‐cyclohexen‐1‐one and 3,5,5‐trimethyl‐2‐cyclohexen‐1‐one have been determined at 298 K and atmospheric pressure by the relative rate technique. OH radicals were generated by the photolysis of methyl nitrite in synthetic air mixtures containing ppm levels of nitric oxide together with the test and reference substrates. The concentrations of the test and reference substrates were followed by gas chromatography. Based on the value k(OH + cyclohexene) = (6.77 ± 1.35) × 10^?11 cm³ molecule^?1 s^?1, rate coefficients for k(OH + 3‐methyl‐2‐cyclohexen‐1‐one) = (3.1 ± 1.0) × 10^?11 and k(OH + 3,5,5‐trimethyl‐2‐cyclohexen‐1‐one) = (2.4 ± 0.7) × 10^?11 cm³ molecule^?1 s^?1 were determined. To test the system we also measured k(OH + isoprene) = (1.11 ± 0.23) × 10^?10 cm³ molecule^?1 s^?1, relative to the value k(OH + (E)‐2‐butene) = (6.4 ± 1.28) × 10^?11 cm³ molecule^?1 s^?1. The results are discussed in terms of structure–activity relationships, and the reactivities of cyclic ketones formed in the photo‐oxidation of monoterpene are estimated. © 2001 John Wiley & Sons, Inc. Int J Chem Kinet 34: 7–11, 2002     

Highly Sensitive and Selective Fluorescence Probe for 2,4‐Dinitrophenylhydrazine Detection in Wastewater Using Water‐Soluble CdTe QDs

A simple, cheap, sensitive and selective probe for determination of DNPH in wastewater using thioglycolic acid (TGA)‐coated CdTe QDs (TGA‐QDs) as fluorescence probe has been established, and the properties of CdTe QDs were characterized by TEM, FT‐IR, DLS, XRD and zeta potentials. CdTe QDs fluorescence is highly efficiently quenched after adding DNPH on account of electron transfer effect, and the fluorescence quenching behavior of CdTe QDs interaction with DNPH is static quenching process. A good linear relationship is observed between the relative fluorescence intensity (F₀/F) and 0.06–10 ng mL^?1 of DNPH. As compared with some of reported methods, LOD of this method for analysis of DNPH (0.23 ng mL^?1) is the lowest. Masking agents of DDTC and NH₄OH can eliminate the interference of Cu²⁺, Ag⁺ and Hg²⁺. Hence, DNPH can be selectively and accurately detected and the established method was successfully used for detecting DNPH in wastewater with acceptable recovery of 90.6–102%.     

P4VP and oligo(phenylenevinylene)‐perylenebisimide mixed donor‐acceptor supramolecular comb polymer complexes with improved charge carrier mobility

Random donor‐acceptor (D‐A) supramolecular comb polymers were formed when hydroxyl functionalized donor and acceptor small molecules based on Oligo(phenylenevinylene) (named OPVCN‐OH ) and Perylenebisimide (named UPBI‐PDP ), respectively, were complexed with Poly(4‐vinyl pyridine) (P4VP). A series of random D‐A supramolecular comb polymers were formed by varying the ratios of UPBI‐PDP and OPVCN‐OH with P4VP. A 100% P4VP‐donor polymer complex [ P4VP(OPV_1.00 )] and a 100% P4VP‐acceptor polymer complex [ P4VP(UPBI_1.00 )] were also synthesized and characterized. Complex formation was confirmed by FT‐IR and ¹H NMR spectroscopy. Solid state structural studies carried out using small angle X‐ray scattering and wide angle X‐ray diffraction experiments revealed altered packing of the D and A molecules in the complexes. Transmission electron microscopy images showed lamellar structures in the < 10 nm scale for the P4VP(OPV_1.00 ), P4VP(UPBI_1.00 ), and mixed P4VP (D‐A) complexes. The effect of the nanoscopic D‐A self‐assembly on the bulk mobility of the materials was probed using SCLC measurements. The mixed D‐A random complexes exhibited ambipolar charge transport characteristics with higher values for the average bulk hole mobility estimate. P4VP(OPV_0.25 + UPBI_0.75) exhibited an average hole mobility in the order of 10^?2cm² V^?1 s^?1 and electron mobility 10^?5cm² V^?1 s^?1. © 2016 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2016 , 54, 2403–2412