Studies on the Lanthanum‐Induced Pinacol Coupling of Aromatic Aldehydes and Ketones in Aqueous Media

The pinacol coupling of aromatic aldehydes and ketones was carried out in 16–71% yield using La–36%HAc–CH₂Cl₂ system with stirring at rt in 4 h. The reactions in the same system gave pinacols in 12–91% yield under ultrasound irradiation at rt in 2 h.     

Allylation Reactions of Aromatic Aldehydes with Antimony in Aqueous Media Under Ultrasonic Irradiation

The allylation reactions of aromatic aldehydes with allyl bromide were carried out in 89–98% yield with Sb-H₂O-KF-CH₃OH under ultrasound irradiation at rt for 2.5 h. The reactions in the same system gave allylic alcohols in 30–69% yield with stirring for 24 h. The main advantages of the present procedure are shorter reaction time, better yield, and environmental friendliness.     

Stannic Chloride–Iodine: An Efficient Reagent for Regioselective Synthesis of Furan–Fused Heterocycles

SnCl₄‐I₂‐mediated cyclization of ortho‐cyclohexenyl phenol and ortho‐cyclohexenyl enol derivatives of coumarin, uracil, dimedone, and pyrone at room temperature for 1 h give the linear cyclized products in 78–90% yield, which, on treatment with 10% Pd‐C at 250°C for 1–2 h, afford corresponding aromatized products in 80–84% yield.     

Facile Access to Mono-Cinchona Alkaloid-Derived Ligands

Two facile accesses to mono-cinchona alkaloid-derived ligands, by conventional heating conditions and solvent-free microwave irradiation, are described. 1,4-Dichlorophthalazine (PHAL) or 3,6-dichloropyridazine (PYDZ) reacted with quinine (QN), cinchonine (CN), or cinchonidine (CND) by using CaH₂ as acid-bonding reagent in DMF at 90–100°C to provide mono-cinchona alkaloid-derived ligands 2a–f (87–95%) in 1.5 h. However, the coupling reactions were performed under solvent-free microwave conditions to yield 2a–f (64–89%) within 15 min.     

Synthesis and biological distribution of 99mTc–norfloxacin complex, a novel agent for detecting sites of infection

The optimization of the radiolabeling yield of ciprofloxacin analogous, norfloxacin, with technetium-99m (^99mTc) was described. Dependence of the labeling yield of ^99mTc–norfloxacin complex on the concentration of norfloxacin, SnCl₂·2H₂O content, pH of the reaction mixture and reaction time was studied. Norfloxacin was labeled with ^99mTc at pH 3 with a labeling yield of 95.4% by using 5 mg norfloxacin, 50 μg SnCl₂·2H₂O and 30 min reaction time. The formed ^99mTc–norfloxacin complex was stable for a time up to 3 h. Biological distribution of ^99mTc–norfloxacin complex was investigated in experimentally induced inflammation rats using Staphylococcus aureus (bacterial infection model) and heat killed Staphylococcus aureus and turpentine oil (sterile inflammation model). In case of bacterial infection, the T/NT value for ^99mTc–norfloxacin complex was found to be 6.9 ± 0.4 which was higher than that of the commercially available ^99mTc–ciprofloxacin under the same experimental condition.     

Dry reforming of greenhouse gases CH4/CO2 over MgO-promoted Ni–Co/Al2O3–ZrO2 nanocatalyst: effect of MgO addition via sol–gel method on catalytic properties and hydrogen yield

Sol–gel method was employed to prepare Ni–Co/Al₂O₃–MgO–ZrO₂ nanocatalyst with various loadings of MgO (5, 10 and 25 wt%) for dry reforming of methane. The physiochemical properties of nanocatalysts were characterized by XRD, field emission scanning electron microscopy (FESEM), energy dispersive X-ray (EDX), BET and fourier transform infrared spectroscopy (FTIR) analysis. Evaluation of catalytic performance was conducted in atmospheric pressure, stoichiometric feed ratio, GHSV of 24 l/g_cat h and temperature range from 550 to 850 °C. XRD patterns represented that as MgO content increases, the amorphous behavior slightly intensifies and also dispersion of active phase improves which probably caused by strong metal–support interaction. Furthermore, FESEM analysis confirmed that all of prepared samples are nano scale. EDX results besides verifying the declared claim about the dispersion of samples proved the presence and detected the position of the various elements. In addition, based on the FESEM analysis, narrow particle size distribution, uniform morphology and dispersion without agglomeration were found for Ni–Co/Al₂O₃–MgO–ZrO₂ with 25 wt% MgO. Moreover, smallest average particle size 11.6 nm (close to the critical size for Ni–Co catalyst to avoid carbon formation) was obtained for this nanocatalyst. Also, according to the BET analysis, MgO rich nanocatalyst represented the higher surface area than the other ones. Based on the excellent characterizations, Ni–Co/Al₂O₃–MgO–ZrO₂ with 25 wt% MgO exhibited the best products yield through all of the investigated temperature e.g. H₂ = 96.9 % and CO = 97.1 % at 850 °C. Furthermore, this nanocatalyst demonstrated the stable yield with H₂/CO close to unit during 1,440 min stability test.     

Radiochemical precipitation studies for separation of iodine from tellurium and other trace impurities

Precipitation of radiotellurium, containing trace radioimpurities, has been carried out from sulfate media at different pH-values. The highest precipitation yield was achieved at the region of pH ~4–6. Quantitative uptake by the formed precipitate was noticed for (i) ⁵⁴Mn, ^110mAg and ¹²⁵Sb over all the pH-range of study (pH 1.7–9.2), (ii) for ⁶⁵Zn and ⁶⁰Co in the regions of pH ~6–8 and pH 6–8.8, respectively, and (iii) for ¹³⁴Cs in the region of pH 1.7–2.8, while its percent uptake fluctuated around 60.5 % in the region of pH 4.4–6.4. Further precipitation studies have been conducted for a mixture of ¹²⁵I and radiotellurium from sulfate, nitrate and chloride media at pH-values of 6.0 and 7.5. The highest ¹²⁵I recovery yield in the obtained supernatant was 95.0 ± 1.3 %, which was achieved with sulfate medium at pH 6.0 with percent uptake values of 5.0 ± 1.3, 98.9 ± 0.9 and 62.0 ± 4.6 % of ¹²⁵I, ^123mTe and ¹³⁴Cs, respectively, and quantitative uptake of ⁵⁴Mn, ^110mAg, ¹²⁵Sb, ⁶⁰Co and ⁶⁵Zn by the precipitated tellurium. Thereafter, the supernatant was further acidified with H₂SO₄ and boiled, after adding H₂O₂, for 3 h. >99 % of ¹²⁵I was distilled off from the acidified supernatant. The distilled of ¹²⁵I was received in 0.1 M NaOH + 1 % Na₂S₂O₃ solution, with a radionuclidic purity of >99.99 %, radiochemical purity of >99.8 % as I^? and pH ~13.     

<Superscript>99m</Superscript>Tc-roxifiban: a potential molecular imaging agent for the detection and localization of acute venous thrombosis

^99mTc-roxifiban was obtained in a high radiochemical yield (98.4%) by complexing ~750 MBq ^99mTc with 2.5 mg roxifiban in the presence of 150 µg SnCl₂·2H₂O. Factors affecting the labelling yield were investigated and optimized. The complex was lipophilic and stable in saline and serum for more than 8 h. The complex structure prediction and molecular docking to its target activated GPIIb/IIIa receptor were performed. The tracer in vitro binding to activated platelets was high (27–32%). In vivo evaluation was performed through clearance, biodistribution and imaging studies in rats. All results supported the usefulness of the tracer as thrombus imaging agent.     

Purification and Characterization of the Glucoside 3-Dehydrogenase Produced by a Newly Isolated Sphingobacterium faecium ZJF-D6 CCTCC M 2013251

A soluble glucoside 3-dehydrogenase (G3DH) was purified from a newly isolated Sphingobacterium faecium ZJF-D6 CCTCC M 2013251. The enzyme was purified to 35.71-fold with a yield of 41.91 % and was estimated by sodium dodecyl sulphate–polyacrylamide gel electrophoresis with a molecular mass of 62 kDa. The sequences of two peptides of the enzyme were all contained in a GMC family oxidoreductase (EFK55866) by mass spectrometry analysis. The optimal pH of the enzyme was around 6.2. The enzyme was stable within a pH range of 5.0–6.6 and was sensitive to heat. G3DH from S. faecium exhibited extremely broad substrate specificity and well regioselectivity to validoxylamine A. The enzyme was completely inhibited by Hg₂Cl₂ and partly inhibited by Cu²⁺, Fe²⁺, Ca²⁺, and Cd²⁺. The apparent K _m values for D-glucose, sucrose, and validoxylamine were calculated to be 1.1, 1.7, and 2.1 mM, respectively. With this purified enzyme, 3-keto sucrose was prepared at pH 5.0, 30 °C for 10 h with a yield of 28.7 %.     

Cellulose hydrolysis catalyzed by highly acidic lignin-derived carbonaceous catalyst synthesized via hydrothermal carbonization

Acidic carbonaceous solids were synthesized from mass pine alkali lignin via hydrothermal carbonization followed by sulfonation. Hydrothermal carbonization of lignin in the presence of acrylic acid (LAHC-SO₃H) provided many more carboxylic groups than that in the absence of acrylic acid, allowing subsequent sulfonation to produce a highly active and stable catalyst for cellulose hydrolysis in the [BMIM]Cl-H₂O solvent system. The hydrochar and catalyst were characterized using field emission scanning electron microscopy, X-ray diffractometer, X-ray photoelectron spectroscopy, thermal gravimetric analysis, Fourier transform infrared spectrometer, Brunauer–Emmett–Teller and acid–base titration. Results showed that a high acid content of 5.48 mmol/g, including carboxylic group (2.85 mmol/g), phenolic hydroxyl group (1.05 mmol/g) and sulfonic acid group (1.58 mmol/g), contributed significantly to the highly efficient hydrolysis of cellulose. Further, it was found that addition of trace water in [BMIM]Cl was favorable to cellulose hydrolysis. The highest yield (75.4%) of total reducing sugar (TRS) obtained in [BMIM]Cl-H₂O at a mass ratio of 100:1 was more than twice that (36.1%) achieved in [BMIM]Cl without water; the corresponding reaction conditions were 50 mg of microcrystalline cellulose, 30 mg of catalyst, 1.0 g of [BMIM]Cl, 10 mg of H₂O, reaction temperature of 130 °C and reaction time of 2 h. Furthermore, the TRS yield with 5 cycles for LAHC-SO₃H was higher than 68.1%, and the catalytic activity of catalyst could be fully recovered (74.0% of TRS yield) easily by regeneration.     

Pretreatment of Chicken Feather Waste for Improved Biogas Production

This study deals with the utilization of chicken feather waste as a substrate for anaerobic digestion and improving biogas production by degradation of the compact structure of the feather keratin. In order to increase the digestibility of the feather, different pretreatments were investigated, including thermal pretreatment at 120 °C for 10 min, enzymatic hydrolysis with an alkaline endopeptidase [0.53–2.66 mL/g volatile solids (VS) feathers] for 0, 2, or 24 h at 55 °C, as well as a combination of these pretreatments. The effects of the treatments were then evaluated by anaerobic batch digestion assays at 55 °C. The enzymatic pretreatment increased the methane yield to 0.40 Nm³/kg VS_added, which is 122 % improvement compared to the yield of the untreated feathers. The other treatment conditions were less effective, increasing the methane yield by 11–50 %. The long-term effects of anaerobic digestion of feathers were examined by co-digestion of the feather with organic fraction of municipal solid waste performed with and without the addition of enzyme. When enzyme was added together with the feed, CH₄ yield of 0.485 Nm³/kg VS^?1 d^?1 was achieved together with a stable reactor performance, while in the control reactor, a decrease in methane production, together with accumulation of undegraded feather, was observed.     

Improved Protocol for Mononitration of Phenols with Bismuth(III) and Iron(III) Nitrates

A simple and efficient multigram procedure was developed for the selective mononitration of various activated phenols. The reaction proceeded smoothly with 0.5 equivalents of Bi(NO₃)₃ · 5H₂O or Fe(NO₃)₃ · 9H₂O in acetone at ambient temperature or at reflux. The desired products were isolated in 62–93% total yield and essentially no overnitrated compounds were detected.     

Synthesis of Dimedone-Annelated Heterocycles: Regioselective Heterocyclization of 2-(Cyclohex-2′-enyl)-5,5-dimethyl-3-hydroxy cyclohex-2-enone

Abstract

2-(Cyclohex-2′-enyl)-5,5-dimethyl-3-hydroxycyclohex-2-enone undergoes regioselective heterocyclization to give bridged heterocycles 5a,b and 7 on treatment with pyridine hydrotribromide or hexamethylenetetramine hydrotribromide (1 h); or elemental bromine (7 h); N-iodosuccinimide in acetonitrile at 0–5°C (1 h) and conc. H₂SO₄ at 0–5°C (2 h), respectively.     

An Expedient Synthesis of Allylic/Secondary Bromides from Dehydration of Tertiary-β-bromo Alcohols

Abstract

Tertiary-β-bromo alcohols, derived from simple monoterpenes and olefins, react with BF₃.OEt₂ in refluxing benzene in 1–2 h to afford the corresponding allylic/secondary bromides in 45–90% yield. In case of substrates containing olefinic or hydroxyl groups, formation of cyclic ethers was observed.     

Preparation process of a highly resistant wollastonite bioceramics using local raw materials

Wollastonite (CaSiO₃) is mainly used for traditional ceramics. In this study, wollastonite-based ceramics was obtained by solid state reaction. The starting powders were sintered at different temperatures (850–1,250 °C) for 2 h. Moreover, different amounts of B₂O₃ (0.5–5.0 mass%) have been added. A relative density of about 97% of the theoretical was reached for samples sintered at 1,050 °C for 2 h, containing 3 and 5 mass% B₂O₃. Excellent values of both three point flexural strength (343 ± 34 MPa) and micro-hardness (4.8 GPa) for samples containing 5 mass% B₂O₃, sintered at 1,050 °C for 2 h. Besides this, a relatively low mass loss ratio has been measured (1.1%) for wollastonite samples containing 5 mass% B₂O₃, sintered under the same conditions, after soaking in lactic acid for 9 days. Finally, the bioactivity of wollastonite by the possibility of formation of apatite on the surface of wollastonite immersed in simulated body fluid was confirmed.     

Electricity production from lignocellulosic biomass by direct coupling of a gasifier and a nickel/yttria-stabilized zirconia-based solid oxide fuel cell: influence of the H<Subscript>2</Subscript>S content of the syngas onto performances and aging

The aim of this work is to study the reactivity of a Ni-YSZ-based solid oxide fuel cell (SOFC) fueled with gaseous mixtures having the same composition as the syngas issued from a fixed-bed downdraft and staged gasification pilot. The syngas issued from the gasifier contains some ppm(v) of H₂S, and in order to adapt the purification process, the influence of this compound on the Ni-YSZ-based SOFCs is evaluated at 600 and 850 °C. The influence of H₂S depends on fuel composition, temperature but also of current density. In H₂–N₂ mixtures and only at 600 °C, a significant decrease of cell performances is observed for H₂S?>?4.5 ppm(v). For H₂–CO–CO₂–N₂ mixtures, the influence is more important since a small decrease of performance can be observed for 1 ppm(v) of H₂S even at 850 °C. Nevertheless, at 600 °C, it is possible to avoid damage by limiting the current density. Aging experiments, realized at 750 °C, show that the influence of 1 and 2 ppm(v) of H₂S is more important during the first 20 h and is reversible: at this temperature, after poisoning with 1 ppm(v) of H₂S during 72 h, the cell recovers 91% of its initial power density after 100 h in pure hydrogen, and after subsequent poisoning with 2 ppm(v) of H₂S during 77 h, the cell recovers 94% of its initial power density after 168 h in pure hydrogen.     

Preparation, nano purification, quality control and labeling optimization of [64Cu]-5,10,15,20-tetrakis (penta fluoro phenyl) porphyrin complex as a possible imaging agent

Cu-64 was produced via the ⁶⁸Zn (p,αn)⁶⁴Cu nuclear reaction (≈200 mCi, >95 % chemical yield at 180 μA for 1.1 h irradiation, (radionuclidic purity >96 %, copper-67 as impurity) followed by purification with amino functionalized nano magnetic oxide, Fe₃O₄ aiming to remove trace amount of heavy metal ions from aqueous media due to achieve ultra pure [⁶⁴Cu] CuCl₂ for labeling step. [⁶⁴Cu] labeled 5,10,15,20-tetrakis(penta fluoro phenyl) porphyrin ([⁶⁴Cu]-TFPP) was prepared using freshly prepared [⁶⁴Cu] CuCl₂ (Cu-64; T _1/2 = 12.7 h) and 5,10,15,20-tetrakis(penta fluoro phenyl)porphyrin (H₂TFPP) for 60 min at 100 °C under reflux condition (radiochemical purity: >97 % ITLC, >98 % HPLC, specific activity: 14–16 GBq/mmol). Stability of the complex was checked in final formulation and human serum for 24 h. The partition coefficient was calculated for the compound (log P = 0.73). The biodistribution of the labeled compound in vital organs of wild-type rats was studied using scarification studies and PET imaging up in 2 and 4 h after injection. A detailed comparative pharmacokinetic study performed for ⁶⁴Cu cation and [⁶⁴Cu]-TFPP. The complex is mostly washed out from the circulation through kidneys and liver and can be an interesting tumor imaging/targeting agent due to high specific uptake and rapid excretion through the urinary tract.     

Synthesis of nanometric β-barium metaborate powder from different borate solutions by ultrasound-assisted precipitation

In this study, the synthesis of barium metaborate powder (BaB₂O₄) was carried out by ultrasound-assisted precipitation using different borate solutions. Different solutions such as borax (Na₂B₄O₇, BD), boric acid (H₃BO₃, BA), and sodium metaborate (NaBO₂, SMB) were used in the synthesis and an ultrasonic immersion horn probe was used as the major source of ultrasound. The effect of reaction temperature and time, pH, and crystallization time on the BaB₂O₄ yield (%) was investigated. The ultrasound-assisted synthesis up to 90 % yield could be achieved using a 0.2 M BD solution at 80 °C, reacting for 5 min at pH 13 followed by 2 h of crystallization. Following crystallization, the obtained powder was heated up to 140, 250, 650, and 750 °C for 2.5 h, and it was shown that β-BaB₂O₄ nanometric powders were obtained after the 750 °C heat treatment.     

Effect of acid treatment of Corich core–Ptrich shell/C electrocatalyst on oxygen reduction reaction

Co_{rich core}–Pt_{rich shell}/C prepared by thermal decomposition and chemical reduction methods were treated by 20% H₂SO₄ aqueous solution and used as the electrocatalysts for the oxygen reduction reaction (ORR). The particle size range of Co_{rich core}–Pt_{rich shell} (molar ratio of 0.92:1) on carbon powder support decreased from 3–8 to 1–6 nm when the time for the electrocatalysts immersed and treated with 20% H₂SO₄ aqueous solution increased from 0 to 4 h. Using Co_{rich core}–Pt_{rich shell} (molar ratio of 0.92:1)/C treated with 20% H₂SO₄ from 0 to 4 h as the working electrode, the open circuit potential of ORR in 0.5 M HClO₄ aqueous solution increased from 0.9995 to 1.0155 V, and the current density, mass activity, and specific activity at the overpotential of 0.1 V increased from 0.619 mA cm^?2, 6.184 A g^?1, and 18.614 μA cm^?2 to 0.912 mA cm^?2, 15.544 A g^?1, and 23.413 μA cm^?2, respectively.     

Microbial Lipid Production from Enzymatic Hydrolysate of Pecan Nutshell Pretreated by Combined Pretreatment

Biodiesel is a fuel composed of monoalkyl esters of long-chain fatty acids derived from renewable biomass sources. In this study, biomass waste pecan nutshell (PS) was attempted to be converted into microbial oil. For effective utilization of PS, sequential pretreatment with ethylene glycol–H₂SO₄–water (78:2:20, wt:wt:wt) at 130 °C for 30 min and aqueous ammonia (25 wt%) at 50 °C for 24 h was used to enhance its enzymatic saccharification. Significant linear correlation was obtained about delignification-saccharification (R ² = 0.9507). SEM and FTIR results indicated that combination pretreatment could effectively remove lignin and xylan in PS for promoting its enzymatic saccharification. After 72 h, the reducing sugars from the hydrolysis of 50 g/L pretreated PS by combination pretreatment could be obtained at 73.6% yield. Using the recovered PS hydrolysates containing 20 g/L glucose as carbon source, microbial lipids produced from the PS hydrolysates by Rhodococcus opacus ACCC41043. Four fatty acids including palmitic acid (C16:0; 23.1%), palmitoleic acid (C16:1; 22.4%), stearic acid (C18:0; 15.3%), and oleic acid (C18:1; 23.9%) were distributed in total fatty acids. In conclusion, this strategy has potential application in the future.