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Extending the applications of Photoremovable Protecting Groups (PPGs) to "cage" phenols has generally met with unusually complex PPG byproducts. In this study, we demonstrate that thep-hydroxyphenacyl (pHP) cage for both simple and complex phenolics, including tyrosine, dispenses free phenols. With the simpler unsubstituted phenols, the reaction is governed by their Bronsted Leaving Group ability. On the other hand, the byproducts of the cage vary with these phenols. For the more acidic phenols the cage byproduct follows the Favorskii rearrangement to formp-hydroxyphenylacetic acid whereas for the weaker phenols other reactions such as reduction and hydrolysis begin to emerge. When the photolysis is conducted in octa acid (OA) containers, non-Favorskii, unrearranged fragments of the cage and other byproducts arise. Kansas University Endowment Association National Institutes of HealthUnited States Department of Health & Human ServicesNational Institutes of Health (NIH) - USA National Science FoundationNational Science Foundation (NSF) [CHE-1807729] FCT - Foundation for Science and TechnologyPortuguese Foundation for Science and Technology [UID/Multi/04326/2019] operational program COMPETE 2020 [EMBRC.PT ALG-01-0145-FEDER-022121] info:eu-repo/semantics/publishedVersion

Ni0.5Zn0.5Fe2−xCrxO4 (0≤x≤0.5) ferrites were successfully prepared by conventional solid state reaction method to investigate the effect of chromium substitution on the structural, electrical and magnetic properties. X-ray powder diffraction results demonstrate that all the prepared samples are well crystallized single-phase spinel structures without secondary phase. As chromium concentration increases, the lattice parameter and crystallite size gradually decrease. The magnetic measurement indicates that saturation magnetization is substantially suppressed by Cr3+ doping, changing from 73.5 A·m2/kg at x=0 to 46.3 A·m2/kg at x=0.5. While the room-temperature electrical resistivity is more than four orders of magnitude enhanced by Cr3+ substitution, reaching up to 1.1×108 Ω·cm at x=0.5. The dielectric constant monotonously decreases with rising frequency for these ferrites, showing a normal dielectric dispersion behavior. The compositional dependence of dielectric constant is inverse with that of electrical resistivity, which originates from the reduced Fe2+/Fe3+ electric dipole number by doping, indicating inherent correlation between polarization and conduction mechanism in ferrite.

Taurine, 2-aminoethane-1-sulfonic acid, is a commercial amino acid manufactured from either ethylene oxide or monoethanolamine (MEA). Taurine is a valuable nutritional additive that is widely used ...

This study investigated the clinical value of diffusion tensor imaging (DTI) in predicting the motor outcome in patients with basal ganglia hemorrhage. This prospective study included 23 patients assessed with DTI to measure the fractional anisotropy (FA) value in affected cortical spinal tract (CST) at three time points: day 0, day 30 and day 90 after onset. The motor function score (MFS) was applied to evaluate motor function and patients were divided into good and poor outcome groups according to the MFS on day 90. The mean FA value on day 0 was significantly lower in the poor outcome group than in the good outcome group (p

The mechanisms of acetylene hydrogenation on palladium clusters (Pdn, n = 2–8) are researched by using the B3PW91/GENECP method of density functional theory. The calculation results indicate that there are two possible pathways for the hydrogenation reaction on Pdn cluster from the reactant acetylene to the product ethane. One of the pathways undergoes through two intermediates, the vinyl (Pdn(H)⋯CH CH2) and ethene (Pdn⋯CH2 CH2) to form the ethane, and the other goes along vinylidene (Pdn(2H)⋯C CH2), ethylidyne Pdn(2H)⋯C CH3) and ethylidene (Pdn(2H)⋯CH CH3) to ethane. Those intermediates in the two pathways can convert into each other which make the reaction profile complicated. The value of n in Pdn cluster can directly affect the reaction pathway: when n ≤ 4, the acetylene hydrogenation reaction will proceed via the pathway of Pdn(2H)⋯CH CH → Pdn(H)⋯CH CH2 → Pdn⋯CH2 CH2 → Pdn(2H)⋯CH2 CH2 to form ethane. However, when n > 4, the reaction choose the following pathway: Pdn(2H)⋯CH CH → Pdn(H)⋯CH CH2 → Pdn⋯CH CH3 → Pdn(2H)⋯CH CH3. In addition, the value of their turnover frequency (TOF) for the ethylene formation catalyzed by Pdn cluster is larger than that for ethane, which indicates that the catalytic cycles in the formation of ethylene is efficient.

Electrospray ionization of methanolic solutions of p-hydroxyphenacyl derivatives HO-C(6)H(4)-C(O)-CH(2)-X (X = leaving group) provides abundant signals for the deprotonated species which are assigned to the corresponding phenolate anions (-)O-C(6)H(4)-C(O)-CH(2)-X. Upon collisional activation in the gas phase, these anions inter alia undergo loss of a neutral "C(8)H(6)O(2)" species concomitant with formation of the corresponding anions X(-). The energies required for the loss of the neutral roughly correlate with the gas phase acidities of the conjugate acids (HX). Extensive theoretical studies performed for X = CF(3)COO in order to reveal the energetically most favorable pathway for the formation of neutral "C(8)H(6)O(2)" suggest three different routes of similar energy demands, involving a spirocyclopropanone, epoxide formation, and a diradical, respectively.

Purpose. Accumulating evidence indicates that oxidative stress may play an important role in the pathogenesis of type 2 diabetes and its complications. Lycopene, a very potent antioxidant of carotenoids, has received considerable scientific interest in recent years for its potential role in the prevention of oxidative stress-related chronic diseases. This study was undertaken to investigate whether the serum levels of lycopene are altered between type 2 diabetic patients with and without diabetic retinopathy. Methods. A total of 71 patients with type 2 diabetes were analyzed and compared with 23 nondiabetic healthy controls. Serum lycopene concentrations were assayed using high-performance liquid chromatography. Results. Lycopene level was found to be significantly lower in diabetic patients than in controls (p=0.021). In the diabetic group, subjects with proliferative diabetic retinopathy had significantly lower lycopene levels than subjects without diabetic retinopathy or with nonproliferative diabetic retinopathy. In the analysis of correlations, hemoglobin A1c were negatively correlated with lycopene (r=–0.345, p=0.007) after multivariate adjustment. A stepwise linear multiple regression model revealed that age and hemoglobin A1c were significant determinants of lycopene. Conclusions. Our findings show that measuring serum lycopene is a novel convenient method for evaluating oxidative damage. Diabetic patients, especially those with advanced diabetic retinopathy, had significantly lower serum lycopene levels; this suggests that lycopene may be helpful for the diagnosis, severity, and therapeutic evaluation of diabetic retinopathy.

Synthesis and thermal decomposition of ammonium aluminum carbonate hydroxide (AACH) have been studied. IR, TG, DTA and XRD results showed that, although AACH aged under different pH might have difference in their composition, the crystal structures are the same. The morphology of AACH and the alumina heated to different temperature were observed in an environment TEM, and no dramatic change has been found during the course. BET results showed the specific surface area of alumina decreased with the increasing heating time and temperature. Size distributions of crystal were measured by using a synchrotron radiation small-angle X-ray scattering (SAXS), the distribution peak shifted to smaller diameter as AACH decomposed to gamma -alumina. then theta -alumina. (C) 2001 Elsevier Science B.V. All rights reserved.

Alzheimer’s disease (AD) is the most common cause of dementia. Global field synchronization (GFS) can measure functional synchronization in frequency-domain electroencephalogram (EEG) data. The aim of this study is to explore GFS values and its clinical significance for severity of cognitive decline in AD. EEGs were recorded from 37 AD patients and 37 age-matched healthy individuals. GFS values were calculated in delta, theta, alpha, beta 1, beta 2, beta 3, gamma, and full frequency bands. The Montreal Cognitive Assessment (MoCA) and Clinical Dementia Rating scale (CDR) were employed to assess symptom severity in AD patients. Correlation analysis, clustering analysis, and concordance analysis were performed to analyze the relationship between GFS values and MoCA scores in AD patients. GFS values of the beta 1, beta 2, beta 3, and full bands were lower in AD patients than in healthy individuals, and positively correlated with MoCA and CDR scores in the combined group (AD patients and healthy individuals). GFS values were positively correlated with MoCA socres in 3 beta bands and full bands, and with CDR scores in the delta band. There was a good concordance between K-means clustering algorithm calculating of GFS values and MoCA scoring (κ = .913, P < .001). In conclusion, the present results indicated that GFS can serve as an indicator of cognitive decline or impairment in AD patients. Furthermore, the GFS method of EEG holds considerable promise to distinguish mild cognitive impairment from serious cognitive impairment in patients with AD.