A synthesis of copper based metal-organic framework for O-acetylation of alcohols

A novel metal-organic framework, Cu–BDC was synthesized by static hydrothermal method using innocuous solvents and characterized by several techniques such as powder XRD, ESR, TG–DTA, elemental analysis, ICP-AES, SEM, EDXS, FT-IR, BET surface area, pore volume and pore size. The catalytic performance of Cu–BDC was explored for O-acetylation of alcohols under solvent-free conditions at room temperature. The catalyst exhibited remarkable activity and reusability affording the desired products in excellent yields.     

New active poly(ethylene glycol) derivative for amino coupling

The synthesis and characterization of an active poly(ethylene glycol) (PEG) derivative with new properties has been afforded starting from a side reaction of N-hydroxysuccinimide (NHS) in presence of N,N-dicyclohexylcarbodiimide (DCC). In particular, a ring opening of NHS in presence of DCC forms a β-alanine active derivative, through Lossen rearrangement, which then reacts with PEG–NH₂ yielding the active PEG derivative: PEG–NH–CO–βAla–NH–CO–NHS. The active group R–NH–CO–NHS showed lower reactivity towards amines and a higher stability in alkaline solution. This can be especially useful in polymer coupling to proteins, because it may lead to a better selectivity among all the amino groups present in a protein, thus yielding less heterogeneous PEG-protein conjugates mixture because only the most nucleophilic and solvent exposed amines can react. A comparison with one of the most used PEGylating agent, the PEG-succinimidyl carboxymethylate (PEG–O–CH₂–CO–NHS), displayed the usefulness of this new PEG derivative for obtaining PEG-protein conjugates. Furthermore, it is of interest that the obtained protein-conjugates are slowly hydrolyzed in water releasing the free protein, therefore they can be considered protein prodrugs.     

Carboxymethyl chitosan-graft-phosphatidylethanolamine: Amphiphilic matrices for controlled drug delivery

Modified carboxymethyl chitosan (CMC) containing phosphatidylethanolamine (PEA) groups were synthesized by a 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide (EDC)-mediated coupling reaction. The structure of the modified CMC exhibiting an amphiphilic character was analysed by FT-IR and ¹H NMR. CMC-g-PEA beads were prepared with sodium tripolyphosphate (TPP) by ionic-crosslinking. The beads sizes were in range from 800 to 1200 μm and encapsulation efficiencies of drug were more than 68%. The morphologies of CMC-g-PEA beads were examined with scanning electron microscopy (SEM). The release experiments were performed using ketoprofen as an hydrophobic model drug. The drug dissolution kinetics showed longer release times for CMC-g-PEA beads: 20 h (at pH 1.4) and 45 h (at pH 7.4). The amount of the drug release was much higher in acidic solution than in basic solution due to the swelling properties of the matrix at acidic pH. These results suggest that modified CMC with PEA may become a potential delivery system to control the release of hydrophobic drugs.     

Morphosynthesis and morphology characterization of aniline and aniline/Laponite films

We report on morphosynthesis techniques that have been employed to tune polyamine film nanoarchitectures and on their resulting morphologies. Specific layers discussed include films of aniline/Laponite clay and aniline solution processed with V₂O₅ catalyst. Synthesis approaches examined include films generated in-situ (glass templating), solution based drop casting, and mechanochemical grinding. Surface topography results suggest that these approaches provide dimensionality control of the polyaniline morphology. Surface images of the mechanochemically ground polyaniline/Laponite nanocomposite layer reveal interfacial contact which is promising for potential heterojunction solar cell designs.     

Fracture and interfacial delamination origins of bilayer ceramic composites for dental restorations

Alumina and zirconia (Y-TZP) based bilayer ceramic dental composites with core to veneer thickness ratio (R-value) of 1:1 and 2:1 were fabricated through an established dental laboratory multi-steps-firing procedure. Their flexural strengths were determined by three-point bending test. A combinational approach of numerical simulations by finite element analysis associated with direct fractography investigation was applied to elucidate the origins of fracture and interfacial delamination and the influence of physical properties mismatch between core ceramic and veneer porcelain. A newly developed argon ion beam cross-section polishing technique was used to conduct fine polishing required for close investigating of the core–veneer interface under scanning electron microscope. For the same core ceramic no significant difference was observed in determined flexural strength of two groups of bilayer composites. The flexural strength of the bilayer composites is ～55% and ～35% of the core ceramics and achieved ～90% and 70–77% of the predicated value respectively in case of Y-TZP and alumina based composites. Numerical simulations by finite element analysis indicate that the often observed interfacial delamination in Y-TZP based bilayer composites has a clear origin of the severe physical properties mismatch between veneer porcelain and core ceramics, particularly the flexural strength, which may be prevented by increasing the flexural strength of veneer porcelain to above 300 MPa. The observation of the formation of microcracks in alumina core immediately one grain-thick under the veneer–core interface warns the possible thermal damages initiated during the veneering operation.     

Real-time TaqMan PCR for quantitative detection of cows’ milk in ewes’ milk mixtures

A real-time PCR based on the amplification of a fragment of the mitochondrial 12S ribosomal RNA gene was developed and evaluated for the detection and quantification of cows’ milk in raw and heat-treated cow/sheep milk mixtures. The method combines the use of cow-specific primers that amplify a 252 bp fragment from cow DNA, and mammalian-specific primers amplifying a 428 bp fragment from mammalian species DNA, which is used as an endogenous control. The method measures PCR product accumulation through a 6-carboxyfluorescein-labeled fluorogenic probe (TaqMan). A comparison of the cycle number at which mammalian and cow-specific PCR products were first detected, in combination with the use of reference standards of known bovine content, allowed the determination of the percentage of cows’ milk in mixtures. Experimental raw and heat-treated binary mixtures were analyzed, demonstrating the specificity and sensitivity of the assay for detection and quantification of cows’ milk in the range 0.5–10%.     

Fabricating carbon nanocages as ORR catalysts in alkaline electrolyte from F127 self-assemble core-shell micelle

In order to reduce the cost of oxygen reduction reaction (ORR) catalyst in fuel cell, polyethylene oxide-polypropylene oxide-polyethylene oxide (PEO-PPO-PEO) three-block copolymer (F127) and Zn(OH)₂ were used as carbon resource and morphology retaining agent to prepare porous nanocages for ORR catalyst in alkaline solution. Its composition and microstructure were characterized by X-ray diffraction Raman spectroscopy (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and Brunauer–Emmett–Teller (BET) method. Electrochemical properties were evaluated in O₂ saturated alkaline solution. Results showed the sample obtained at 700 °C (C-700) was composed of porous carbon nanocages with diameter of 50 nm and shell thickness of 4 nm. C-700 had the maximum surface area (1011 m² g⁻¹) and the best ORR catalytic performance. The main reason is that polypropylene oxide (PPO) group at the lipophilic end begins to decompose at 500 °C, and the polyethylene oxide (PEO) group at the lipophilic end at 700 °C decomposes completely. In O₂ saturated 0.1 M KOH solution, C-700's oneset potential, limit current density and half-wave potential, which were 0.89 V, 5.59 mA/cm²@0.45 V and 0.71 V, respectively, were close to that of commercial 20% Pt/C catalyst. It was noted that the oneset potential and half-wave potential of C-700 had barely change, and limit current density attenuated about 87.8% after 2000 CV cycle. The obtained catalyst behaved good catalytic activity and stability for ORR in alkaline solution and a potential application prospect in fuel cells.     

冷榨花生粕蛋白胨酶法制备及其在微生物增殖培养中的应用

为探讨冷榨花生粕蛋白质酶法制备蛋白胨替代商用蛋白胨的可行性,将冷榨花生粕用胃蛋白酶与碱性蛋白酶进行双酶协同水解制备冷榨花生粕蛋白水解物（也称为冷榨花生粕蛋白胨）,并分析其分子质量分布、化学组分分析及氨基酸组成。研究发现,经双酶协同水解后的冷榨花生粕蛋白胨主要由小于5.0 kDa的肽段组成,富含丙氨酸、精氨酸、天冬氨酸、半胱氨酸等氨基酸,特别是谷氨酸含量较高。微生物增殖培养实验结果表明,大肠杆菌在冷榨花生粕蛋白胨培养基中培养8 h后比牛肉膏蛋白胨中生长情况好;枯草芽孢杆菌在冷榨花生粕蛋白胨培养基中比LB培养基中有较长的滞后期,但培养8 h后,生长情况比LB培养基更好;大肠杆菌和枯草芽孢杆菌在冷榨花生粕蛋白胨培养基和对照培养基中pH值变化差异不显著（P＞0.05）;干酪乳杆菌在冷榨花生粕蛋白胨培养基和MRS培养基中生长情况有显著差异（P＜0.05）;金黄色葡萄球菌在冷榨花生粕培养基中与对照培养基生长差异不显著（P＞0.05）;酿酒酵母在冷榨花生粕培养基中与对照生长有类似的生长曲线与pH值变化趋势;米曲霉在冷榨花生粕培养基中与对照培养生长无显著差异（P＞0.05）。结果表明,冷榨花生粕蛋白胨在替代商用蛋白胨用于微生物的增殖培养应用中具有很好的潜力。     

花生肽亚铁稳定性及胃肠仿生消化行为研究

为研究花生肽亚铁口服后的人胃肠仿生消化行为及降解规律,以不同相对分子质量(1.0 kDa、 1.0～3.0 kDa、3.0 kDa)的花生肽为载体,以氯化亚铁为配体,分别制备L-PPC、M-PPC和H-PPC,考察了其稳定性和胃肠消化耐受性。研究表明:L-PPC比M-PPC和H-PPC具有更好的pH稳定性且存在极显著差异(p0.01),H-PPC的pH稳定性最差;H-PPC热耐受性最差,特别是温度超过50℃后,亚铁螯合率低于50%,与L-PPC和M-PPC有极显著差异(p0.01),L-PPC热耐受性最好;L-PPC胃酸耐受性明显高于M-PPC和H-PPC,胃仿生消化30 min,L-PPC和M-PPC亚铁螯合率差异不显著(p0.05),与H-PPC差异极显著(p0.01);胃仿生消化90 min和120 min时,M-PPC和H-PPC的亚铁螯合率分别为(71.83%±1.32)%、(56.61±1.16)%和(61.46±1.25)%、(53.90±1.33)%;胃仿生消化120 min时,L-PPC、M-PPC和H-PPC相对于胃仿生消化30 min,亚铁螯合率残存率分别为91.15%、69.05%和74.10%。M-PPC和H-PPC经十二指肠仿生消化60 min时,亚铁螯合率分别下降至(57.93±0.83)%、(45.65±0.87)%,再经小肠仿生消化180 min,亚铁螯合率分别下降至(38.42±0.85)%、(18.34±0.72)%,与L-PPC差异极显著(p0.01),L-PPC具有较好的肠耐受性,H-PPC肠耐受性最差。结果说明,L-PPC相比M-PPC和H-PPC具有更优良的pH稳定性、热耐受性和胃肠消化耐受性。