Serum 25-hydroxyvitamin D is associated with stroke history in a reverse J-shape.

Background: 25-hydroxyvitamin D [25(OH)D], the major form of vitamin D in the body, has a non-linear association with stroke risk. However, the association is not fully understood. The specific shape of the association and the ideal value of 25(OH)D related to minimum risk of stroke remain unclear. Aim: We conducted the study to establish the correlation between circulating 25(OH)D and stroke history and determine the ideal value of 25(OH)D in relation to the lowest stroke prevalence. Methods: Data from the National Health and Nutrition Examination Survey (NHANES) were used for analyzes. We used multivariate logistic regression analysis with fitted smooth curves to explore the relationship between 25(OH)D and self-reported stroke history. Subsequently, 40,632 participants were enrolled in the study. Results: A reverse J-shaped association between 25(OH)D and stroke history was determined, where the lowest stroke prevalence for the 25(OH)D level was about 60 nmol/L. After adjusting for confounding factors, prevalence of stroke showed an increasing trend below and above the middle quintile (53.2-65.4 nmol/L) of 25(OH)D. Participants with 25(OH)D levels in the lowest quintile (≤ 39.3 nmol/L) had a 38% increased prevalence of stroke (OR 1.38, 95 %CI 1.12-1.70), while those in the higher level range of 25(OH)D (65.5-80.8 nmol/L) had a 27% higher stroke prevalence (OR 1.27, 95 %CI 1.03-1.57). Conclusion: Using data from a large, cross-sectional cohort program, we found that circulating 25(OH)D was related to stroke history in a reverse J-shaped manner. Given how the causal relationship between circulating 25(OH)D and history of stroke has not been established, more high-quality evidence based on the reverse J-shaped feature is needed to elucidate the link between vitamin D and stroke risk, and the effect of vitamin D supplements on stroke prevention.

Performance and mechanism of oxidation, and removal of trace SeO2 in flue gas utilizing a H2O2, NaClO2, and Ca2+ slurry.

Selenium (Se) is one of the toxic trace elements in flue gas emitted from coal-fired power plants. A method for oxidation and absorption of selenium dioxide (SeO2) by hydrogen peroxide (H2O2) and sodium chlorite (NaClO2) in a calcium-based slurry is proposed, in which hydrated lime (Ca(OH)2) and calcium carbonate (CaCO3) were selected to be absorbents, and H2O2 and NaClO2 were used to oxidize SeO2 and selenite ion to selenate ion to reduce their toxicities. The effects of reaction temperature, H2O2 and NaClO2 concentrations, solution pH, and SeO2 concentration were investigated, from which the optimal reaction conditions were established. The results indicated that the oxidation efficiency was affected significantly by the solution pH, and H2O2 and NaClO2 concentrations. The oxidation efficiency of SeO2 and selenite ion to selenate ion was below 40% using H2O2 and that increased to 92% with NaClO2 at the optimal conditions. For removal, Ca(OH)2 and CaCO3 slurries were used as absorbents and the efficiencies were affected by the slurry temperature. Oxidation behavior and mechanism were analyzed based on the characterization of removal products using hydride generation-atomic fluorescence spectrometry and X-ray photoelectron spectroscopy. SeO2 and selenite ion can be oxidized to selenate ion, which is less toxic, by active species such as hydroxyl radicals (HO·) and chlorine dioxide (ClO2), which are released during the decomposed processes of H2O2 and NaClO2 in acid conditions.

Predictive efficacy of the Braden Q Scale for pediatric pressure ulcer risk assessment in the PICU: a meta-analysis.

BACKGROUND: Risk assessment is recommended as the foremost step in the prevention of pressure ulcers. This study aimed to evaluate the predictive efficacy of the Braden Q Scale for the assessment of pediatric pressure ulcer risk in the pediatric intensive care unit (PICU). METHODS: Six databases were searched. A meta-analysis was performed using Meta DiSc 1.4. RESULTS: Seven studies were included, with a total of 1273 cases and 72 pressure ulcers. The meta-analysis showed that the pooled sensitivity and specificity of the Braden Q Scale for PICU patients were 0.72 and 0.60 (95% confidence interval (CI): 0.60-0.82; 0.57-0.63), respectively. The pooled positive likelihood ratio, negative likelihood ratio, and diagnostic odds ratio were 1.69, 0.62, and 3.34 (95% CI: 1.18-2.42; 0.40-0.94; 1.47-7.61), respectively. The area under the curve of summary receiver operating characteristics was 69.18%, and the Q index was 0.6464. CONCLUSION: The Braden Q Scale predicted pressure ulcer risk in the PICU with moderate accuracy. More testing for the Braden QD Scale's performance is needed, taking into account the impact of the interventions. In the future, it will be necessary to look for and improve pediatric pressure ulcer risk assessment tools.

Cyclopentadienones via a tandem C-cyclopropylnitrone cyclization-cycloreversion sequence.

Aldonitrones derived from spiro[2.4]hepta-4,6-diene-1-carbaldehyde and its benzo analog undergo a tandem uncatalyzed intramolecular cyclopropane-nitrone cyclization-5,6-dihydro-1,2-oxazine cycloreversion to give cyclopentadienones. Similarly, the NH-nitrone generated in situ from spiro[cyclopropane-1,1'-indene]carbaldehyde oxime leads to benzocyclopentadienone (1H-inden-1-one) by the same mechanism. DFT calculations are in favor of a concerted yet highly asynchronous pathway for the cyclizations. Control experiments with the dihydro and tetrahydro derivatives show that the spirocyclopentadiene unit is essential for the success of the reaction, invoking spiroconjugative effects for increased cyclopropane reactivity.

Pyrrolidine catalyzed reactions of cyclopentadiene with α,ß-unsaturated carbonyl compounds: 1,2- versus 1,4-additions.

A systematic study of the reactions of cyclopentadiene with α,ß-unsaturated carbonyl compounds in the presence of catalytic pyrrolidine-H2O revealed that the reactions can either proceed with a Michael attack at the ß-carbon of enone, or 1,2-addition to the carbonyl, leadingeither to 4-cyclopentadienyl-2-butanones or 6-vinylfulvenes. The former can be isolated and/or converted to the corresponding 1,2-dihydropentalenes with base (or in one-pot at longer reaction times). Substitution pattern on the enones on the competing pathways have been studied and consistent mechanisms are proposed.

Effect of allylic groups on S(N)2 reactivity.

The activating effects of the benzyl and allyl groups on S(N)2 reactivity are well-known. 6-Chloromethyl-6-methylfulvene, also a primary, allylic halide, reacts 30 times faster with KI/acetone than does benzyl chloride at room temperature. The latter result, as well as new experimental observations, suggests that the fulvenyl group is a particularly activating allylic group in S(N)2 reactions. Computational work on identity S(N)2 reactions, e.g., chloride(-) displacing chloride(-) and ammonia displacing ammonia, shows that negatively charged S(N)2 transition states (tss) are activated by allylic groups according to the Galabov-Allen-Wu electrostatic model but with the fulvenyl group especially effective at helping to delocalize negative charge due to some cyclopentadienide character in the transition state (ts). In contrast, the triafulvenyl group is deactivating. However, the positively charged S(N)2 transition states of the ammonia reactions are dramatically stabilized by the triafulvenyl group, which directly conjugates with a reaction center having S(N)1 character in the ts. Experiments and calculations on the acidities of a variety of allylic alcohols and carboxylic acids support the special nature of the fulvenyl group in stabilizing nearby negative charge and highlight the ability of fulvene species to dramatically alter the energetics of processes even in the absence of direct conjugation.

Temperature-dependent, competitive 1,3-acyl shift versus decarbonylation of a cyclopropanone intermediate.

Photooxygenation of 1,1,3-trimethyl-1,2-dihydropentalene gives an unstable endoperoxide which upon decomposition delivers a bicyclic cyclopropanone intermediate; this species either extrudes CO to give a cycloheptadienone or undergoes a 1,3-acyl shift, both processes occurring most likely in a stepwise manner via diradical intermediates. Alternatively, C3a-C4 cleavage in the dioxygen diradical derived from the endoperoxide yields a 2-cyclopropyl substituted cyclopentadienone epoxide.

Advances on simultaneous desulfurization and denitrification using activated carbon irradiated by microwaves.

This paper describes the research background and chemistry of desulfurization and denitrification technology using microwave irradiation. Microwave-induced catalysis combined with activated carbon adsorption and reduction can reduce nitric oxide to nitrogen and sulfur dioxide to sulfur from flue gas effectively. This paper also highlights the main drawbacks of this technology and discusses future development trends. It is reported that the removal of sulfur dioxide and nitric oxide using microwave irradiation has broad prospects for development in the field of air pollution control.

1,2-Dihydropentalenes from fulvenes by [6 + 2] cycloadditions with 1-isopropenylpyrrolidine.

In situ generated acetone pyrrolidine enamine undergoes [6 + 2] cycloadditions with fulvenes to give 1,2-dihydropentalenes. This ring annulation method works particularly well with 6-monosubstituted fulvenes and is subject to steric hindrance at C-6 of the fulvene. On the basis of mechanistic studies, optimal conditions have been developed for a one-pot synthesis of 1,2-dihydropentalenes using catalytic amounts of pyrrolidine.

One electron oxidation of triferrocenylmethanol: synthesis, metal atom dynamics, electron delocalization, and the crystal structure of [Fc3COH](+) PF6⁻.

The title compound 2 was prepared and its crystal structure was determined at 100 K. The neat solid was examined by temperature dependent (57)Fe Mössbauer effect (ME) spectroscopy over the interval 92 < T < 318 K, and evidences two diamagnetic Fe(II) sites and one paramagnetic Fe(III) site. The latter shows spin-lattice relaxation, but there is no evidence of electron delocalization among the three iron sites in the above temperature interval. The mean-square-amplitude-of-vibration of the diamagnetic iron site has been determined from the recoil-free fraction ME resonance, and compared to the neutral Fc(3)COH homologue (1). The ME dynamical data are in good agreement with the U(i,j) value at 100 K extracted from the crystallographic results. The ME parameters at 5 K have also been determined with the sample compound embedded in a paraffin wax matrix as well as pelletized with BN.

Transannular addition of phenols to 1,1'-dialkynylferrocenes: unanticipated formation of phenoxy[4]ferrocenophanedienes.

The reaction of some 1,1'-dialkynylferrocenes with a variety of phenols in the presence as well as in the absence of [Mo(CO)(6)] yields good to high yields of phenoxy[4]ferrocenophanedienes. Similar reactivity was observed with a thiophenol and with acetic acid. Reaction under basic reaction conditions led to the formation of the [4]ferrocenophanone 17. The phenoxy[4]ferrocenophanedienes obtained show dynamic behavior as a result of a torsional twist of the carbon bridge as indicated by the (1)H and (13)C NMR spectra. The reaction mechanism is discussed in view of recent related results of Sato et al. as well as of Pudelski et al. A vinyl cation intermediate is postulated in this context, whose relative stability is evident from the mass spectra of the compounds prepared.

Metal atom dynamics in four triferrocenylmethane derivatives and the crystal structure of Fc3COH.

The metal atom dynamics of four triferrocenylmethane derivatives have been elucidated, using temperature-dependent 57Fe Mössbauer effect (ME) spectroscopy. The hyperfine parameters (IS and QS) at 90 K are compared to each other and those of related ferrocenoids. The metal atom vibrational amplitudes as a function of temperature have been extracted from the ME recoil-free fraction data, and are compared to the X-ray U(i,j) values for two of the compounds. The single crystal structural data for triferrocenylmethanol have been determined at 173 and 295 K. The vibrational anisotropy of the metal atom for all of the compounds is negligibly small over the accessible temperature range.

[Experiment study on the aqueous removal of SO2 by Mn2+ catalytic ozonation].

The removal of SO2 by Mn2+ catalytic aqueous ozonation was investigated by experiment, so as to find the effects of Mn2+ for aqueous removal of SO2 by ozonation. The concentration curve of ozone was drawn by standard iodine method. The operating factors included mole ratio of ozone to sulfur dioxide and concentration of Mn2+. When absorption solution has no Mn2+, the removal efficiency of SO2 was 35% at [O3 ]/[SO2 ] = 0.5,but the efficiency was 70% when Mn2+ was put into absorption solution at the same value of [O3 ]/[SO2].With the increasing of [3O]/[SO2], the removal efficiency of SO2 increases. And as concentration of Mn2+ increases, the efficiency also increases. There is an appropriate concentration range which is 1.2 x 10(-2)-1.2 x 10(-1) mol/L for Mn2+.

[Experimental research for simultaneous removal of SO2 and NOx by aqueous oxidation of O3].

The removal of SO2 and NOx by aqueous oxidation of O3 was studied by self-designed bubbling reactor. The results show that NO can be oxidized efficiently by O3 in liquid phase, while the existence of SO2 has a negative impact on the removal of NO and pH value has a little impact. The NO removal efficiency is 89.6% at [O3]/[NO] = 1.1. When the rang of pH value is in 3-11, NO removal efficiency can be achieved over 80%. At 20-65 degrees C, NO removal efficiency has no change. Combining with wet scrubbing tower, SO2 removal efficiency is nearly 100% and NO2 removal efficiency is 84.2% at [O3]/[NO] = 1.1. SO2 and NOx can be removed effectively by aqueous oxidation of O3 simultaneously.