333 research outputs found
ZnO/ionic liquid catalyzed biodiesel production from renewable and waste lipids as feedstocks
A new protocol for biodiesel production is proposed, based on a binary ZnO/TBAI (TBAI = tetrabutylammonium iodide) catalytic system. Zinc oxide acts as a heterogeneous, bifunctional Lewis acid/base catalyst, while TBAI plays the role of phase transfer agent. Being composed by the bulk form powders, the whole catalyst system proved to be easy to use, without requiring nano-structuration or tedious and costly preparation or pre-activation procedures. In addition, due to the amphoteric properties of ZnO, the catalyst can simultaneously promote transesterification and esterification processes, thus becoming applicable to common vegetable oils (e.g., soybean, jatropha, linseed, etc.) and animal fats (lard and fish oil), but also to waste lipids such as cooking oils (WCOs), highly acidic lipids from oil industry processing, and lipid fractions of municipal sewage sludge. Reusability of the catalyst system together with kinetic (Ea) and thermodynamic parameters of activation (âG⥠and âHâĄ) are also studied for transesterification reaction
Concerning the reactivity of dioxiranes. Observations fromexperiments and theory
The challenging hypothesis of a âbiphilicâ (i.e., electrophilic vs nucleophilic) character for dioxirane
reactivity, which envisages that electron-poor alkenes are attacked by dioxiranes in a nucleophilic fashion,
could not be sustained experimentally. Rate data, which estimate Hammett ârhoâ values for the epoxidation
of 3- or 4-substituted cinnamonitriles XĂąPhsCHdCHsCN, unequivocally allow one to establish that
dioxiranes epoxidize electrophilically even alkenes carrying electron-withdrawing groups. The greater
propensity of methyl(trifluoromethyl)dioxirane TFDO (1b) to act as an electrophilic oxidant with respect to
dimethyldioxirane DDO (1a) parallels the cathode reduction potentials for the two dioxiranes, as measured
by cyclic voltammetry. A simple FMO approach for alkene epoxidation is helpful to conceive a likely rationale
for the greater oxidizing power of TFDO as compared to DDO
A selective cellulose/hemicellulose green solvents extraction from buckwheat chaff
A two-phase extraction process was adopted to obtain cellulose and hemicellulose from buckwheat chaff by using green solvents. We are proposing a combination of propylene carbonate (PC) and ionic liquids (ILs) in a 1:5 ratio. We compared the first-generation ILs 1-butyl-2,3-dimethylimidazolium chloride (BdmimCl), and 1-butyl-3-methyl imidazolium acetate (BmimAc) with respect to the tetrabutyl ammonium acetate (TBAAc). The cellulose and hemicellulose were, firstly, extracted into the PC/IL mixture and subsequently precipitated by water addition. All precipitate materials were analysed by FTIR-ATR and TGA, while the organic phase and the supernatant after water addition were analysed by using self-diffusion NMR. The PC green co-solvent was proven to be an exceptional candidate to replace dimethyl sulfoxide. The highest amount of precipitate material after water addition was obtained with PC-BmimAc, while PC-TBAAc was showing the highest cellulose/hemicellulose selectivity. Furthermore, a preferential interaction of the supernatant cellulose residue with PC or acetate was observed by self-diffusion NMR
Deep Control of Linear Oligomerization of Glycerol Using Lanthanum Catalyst on Mesoporous Silica Gel
The valorization of glycerol (1), a waste of biodiesel production of Fatty Acid Methyl Esters (FAMEs), adopting a âgreenâ approach, represents an important goal of sustainable chemistry. While the polymerization of 1 to hyperbranched oligomers is a well-established process, the linear analogues are difficult to obtain. In this context, we explore the reaction without the solvent of heterogeneous hybrid La(III)O-KIT-6 catalyst (2), which is based on lanthanum oxide on mesoporous silica gel, showing a superior linear selectivity compared to most of the analogous catalysts recently reported
Green procedure for one-pot synthesis of azelaic acid derivatives using metal catalysis
Background & Objective: A green one-pot synthesis of oleic acid (1) derivatives is promoted by Rare Earth Metal (REM) triflates and commercial Molybdenum dioxo dichloride (MoCl 2 O 2 ) in the presence hydrogen peroxide as a green oxidant. Results: The protocol permits to govern the oxidation selectivity by simply choosing the proper combination of Mo and Sc catalysts. Conclusion: Methyl oleate epoxide 2a and azelaic acid 6 thus obtained are valuable industrial intermediates for synthesizing bio-compostable plastics, plasticizers of PVC, lubricating oils, cosmetics and pharmaceuticals (bactericides, anti-inflammatories, etc.)
KIR-HLA Genotypes in HIV-Infected Patients Lacking Immunological Recovery despite Effective Antiretroviral Therapy
BACKGROUND: In HIV-infected individuals, mechanisms underlying unsatisfactory immune recovery during effective combination antiretroviral therapy (cART) have yet to be fully understood. We investigated whether polymorphism of genes encoding immune-regulating molecules, such as killer immunoglobulin-like receptors (KIR) and their ligands class I human leukocyte antigen (HLA), could influence immunological response to cART. METHODS: KIR and HLA frequencies were analyzed in 154 HIV-infected and cART-treated patients with undetectable viral load divided into two groups: 'immunological non responders' (INR, N = 50, CD4(+) T-cell count <200/mm(3)) and full responders (FR, N = 104, CD4(+) T-cell count >350/mm(3)). Molecular KIR were typed using polymerase chain reaction-based genotyping. Comparisons were adjusted for baseline patient characteristics. RESULTS: The frequency of KIR2DL3 allele was significantly higher in FR than in INR (83.7% vs. 62%, P = 0.005). The functional compound genotype HLA-C1(+)/KIR2DL3(+), even at multivariable analysis, when adjusted for nadir CD4(+) T-cell count, was associated with reduced risk of INR status: odds ratio (95% Confidence Intervals) 0.34 (0.13-0.88), P = 0.03. CONCLUSIONS: Reduced presence of the inhibitory KIR2DL3 genotype detected in INR might provoke an imbalance in NK function, possibly leading to increased immune activation, impaired killing of latently infected cells, and higher proviral burden. These factors would hinder full immune recovery during therapy
Gender may be related to the side of the motor syndrome and cognition in idiopathic Parkinson's disease.
Abstract Background and Sex and cognitive profile may be related to the laterality of motor symptoms in idiopathic Parkinson's disease. Introduction Parkinson's disease (PD) is well recognised as an inherently asymmetric disease with unilateral onset of motor symptoms. The laterality of motor symptoms may be linked to sex, clinical and demographic variables, and neuropsychological disorders. However, the available data are inconsistent. This study aimed to explore the potential association between the laterality of motor symptoms and clinical and demographic variables and deficits in specific cognitive domains. Material and methods We retrospectively recruited 97 participants with idiopathic PD without dementia; 60 presented motor symptoms on the left side and 37 on the right side. Both groups were comparable in terms of age, age at disease onset, disease duration, and severity of the neurological deficits according to the Unified Parkinson's Disease Rating Scale and the Hoehn and Yahr scale. Results Participants with left-side motor symptoms scored lower on the Schwab and England Activities of Daily Living scale. Our sample included more men than women (67% vs. 33%). Both sexes were not equally represented in the 2 groups: there were significantly more men than women in the group of patients with left-side motor symptoms (77% vs. 23%), whereas the percentages of men and women in the group of patients with right-side motor symptoms were similar (51% vs. 49%). Both groups performed similarly in all neuropsychological tasks, but women, independently of laterality, performed better than men in the naming task. Conclusion We found a clear prevalence of men in the group of patients with left-side motor symptoms; this group also scored lower on the Schwab and England Scale. Female sex was predictive of better performance in the naming task. Sex should always be considered in disorders that cause asymmetric involvement of the brain, such as PD
How microanalysis can be discriminant on black Pompeian wares
In the present work the advantages of punctual approaches are discussed in the discrimination of black wares from the Sanctuary of Venus Fisica (Pompeii, Italy), dated between the 2nd and 1st century BC. Black-gloss ware and "bucchero" samples are analyzed by a multi-analytical approach including optical microscopy (OM), X-ray powder diffraction (XRPD), scanning electron microscopy with Energy Dispersive Spectroscopy (SEM-EDS) and electron microprobe analysis (EMPA) to investigate the mineralogical and petrographic features of these artefacts. Grain size, firing conditions and potterâs expertise influenced the final appearance of the superficial decorative black layer. In addition, punctual chemical analysis was fundamental to verify the archaeological indication of specific production sites
Metastasis-Directed Radiation Therapy with Consolidative Intent for Oligometastatic Urothelial Carcinoma: A Systematic Review and Meta-Analysis
The management of patients with oligometastatic urothelial carcinoma (UC) represents an evolving field in uro-oncology, and the role of metastasis-directed therapies, including metastasectomy and metastasis-directed radiation therapy (MDRT), is gaining increasing attention. Herein, we summarize available evidence about the role of MDRT with consolidative intent in oligometastatic UC patients. A systematic review was performed in December 2021. Six studies involving 158 patients were identified. Most patients (n = 120, 90.2%) had a history of bladder cancer and the most frequent sites of metastases were lymph nodes (n = 61, 52.1%) followed by the lungs (n = 34, 29%). Overall, 144 metastases were treated with MDRT. Median follow-up ranged from 17.2 to 25 months. Local control rates ranged from 57% to 100%. Median Overall Survival (OS) ranged from 14.9 to 51.0 months and median progression-free survival ranged from 2.9 to 10.1 months. Rates of OS at one and two years ranged from 78.9% to 96% and from 26% to 63%, respectively. Treatment-related toxicity was recorded in few patients and in most cases a low-grade toxicity was evident. MDRT with consolidative intent represents a potential treatment option for selected patients with oligometastatic UC
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