Addition Of Zinc Acetate Research Articles

Controllable preparation of carbon nanofiber membranes for enhanced flexibility and permeability

The electrospinning-produced carbon nanofiber membranes (CNFM) have been applied in many fields for their three-dimensional porous networks, however, the natural fragility impedes their practical applications. Introducing plasticizers into carbon fibers has been proven an efficient way to increase the flexibility of CNFM but the extent is limited. This work explored dual plasticizers strategy to improve the flexibility of CNFM. The addition of zinc acetate and tetraethyl orthosilicate leads to bigger carbon nanofibers and higher mean pore diameters. They can be transformed into SiO2 and ZnO nanoparticles that embed in the carbon fibers, and act as plasticizers to inhibit stress diffusion. The Young's modulus of the optimal SZCNFM-2.0-1.5-700 is 31.0 MPa, which is lower than single plasticizer can reduce. The mechanism of dual plasticizers collaboratively improving the flexibility of SZCNFM was proved based on the characterization results. The SZCNFM-2.0-1.5-700 with well flexibility also revealed high permeability, for instance, the gravity-induced cyclohexane flux is 486.67 L m−2 h−1. Furthermore, the SZCNFM-2.0-1.5-700 requires only half the time compared to the commercial filter membrane when separating the same amount of Pd@CN suspension in the suction filter.

Effects of low frequency multi-mode ultrasound and it’s washing solution’s interface properties on freshly cut cauliflower

This study investigated the effect of single and dual frequency ultrasound washing on freshly cut cauliflower, by pulsed and sweep frequency modes, with or without the addition of zinc acetate (ZA), tea saponin (TS) and ethanol (ET). Results showed that the surface microorganisms were efficiently decreased by sweep dual frequency ultrasound washing. Moreover, the use of 0.5% ZA, or 0.06% TS or 5% ET as washing solution improved the bacterial reduction efficiency. Reducing the interfacial tension, viscosity and contact angle of washing solution may strengthen ultrasound cavitation. Nearly 2.0 log CFU/g natural microorganisms were decreased, and shelf life was extended from 2 to 4–8 days under 4 °C. Physicochemical parameters of bioactive compounds content, enzyme activity, antioxidant ability, freshness were analyzed. Results showed that 0.5% ZA as washing solution of ultrasound washing was beneficial to the quality maintenance during storage period.

High electrochemical and mechanical performance of zinc conducting-based gel polymer electrolytes

Zinc ionic conducting-based gel polymer electrolytes (GPEs) were fabricated from carboxymethyl cellulose (CMC) and three different zinc salts in a mass ratio ranging within 0–30 wt%. The effects of zinc salt and loading level on the structure, thermal, mechanical, mechanical stability, and morphological properties, as well as electrochemical properties of the GPEs films, were symmetrically investigated. The mechanical properties and mechanical stability of CMC were improved with the addition of zinc acetate, zinc sulphate, and zinc triflate, approaching the minimum requirement of a solid state membrane for battery. The maximum ionic conductivity of 2.10 mS cm−1 was achieved with the addition of 15 wt% zinc acetate (ZnA), GPEA15. The supported parameters, indicating the presence of the amorphous region that likely supported Zn2+ movement in the CMC chains, were clearly revealed with the increase in the number of mobile Zn2+ carriers in FT-IR spectra and the magnitude of ionic transference number, the decrease of the enthalpy of fusion in DSC thermogram, and the shifting to lower intensity of 2θ in XRD pattern. The developed CMC/ZnA complex-based GPEs are very promising for their high ionic conductivity as well as good mechanical properties and the ability for long-term utilization in a zinc ion battery.

Surface micro-alcoholysis treatment: A novel approach towards froth flotation based separation for binary mixtures of polyethylene terephthalate and polyvinyl chloride

It is known that selective separation is the prerequisite of recycling pathways for waste plastics, which brings the potential economic and environmental benefits for cleaner production. A novel approach, surface micro-alcoholysis treatment (SMAT), was proposed for improvement of froth flotation towards the separation of plastics. By means of the SMAT, binary mixtures of polyethylene terephthalate (PET) and polyvinyl chloride (PVC) were selective modified to achieve effective separation. The mechanism of SMAT was examined by multiple characterization tests, response surface methodology was employed for its statistical optimization and simulation of pilot plant was first applied. The results suggested that selective wetting could be achieved through SMAT. PET surface was partially replaced by hydrophilic oligomers after ester exchange reaction, leading to the final flotation separation. Based on Plackett-Bueman design, zinc acetate concentration, temperature and operating time were identified as the significant factors controlled in SMAT. The maximum validation separation purity of PET could even reach 99.25% under the optimal condition predicated by Box-Behnken design. Such condition was performed in detail as the mass volume ratio of 1:5 (poly mixtures: 2-ethylhexanol), 0.3 wt% addition of zinc acetate, temperature of 346.5 K, stirring intensity of 100 rpm and operating time of 84.13 min. The PET purity was verified to be steady around 95% in simulation of pilot plant. The proposed technology is efficient, reliable in operation, widespread of application and potential of industrialization.

The synthesis and characterization of zinc-containing electrospun chitosan/gelatin derivatives with antibacterial properties.

Homogenous allocation of inorganic particles in a polymeric matrix is a challenge. In this work, we discuss electrospinning of chitosan /gelatin using CS-Si (chitosan silicone hybrids) as well as the formation of homogeneously distributed Zn elements inside chitosan nanofiber through chitosan -GPTMS hybrids. Chitosan -GPTMS hybrids can be synthesized by acid catalyzed amino-oxirane addition reaction. The proposed mechanism was approved by using spectral and elemental analyses. The chitosan derivative Si-Cs was mixed with gelatin and their solution were applied to electrospinning. Optimization of spinning process is reached. A homogeneous spinnable solution with desirable properties is obtained by addition of Zinc acetate. The characterizations of the spinnable solution in term of electrical conductivity and viscosity were studied. Characterization of the nanofiber formed by SEM show that there is no Zn accumulated on the nanofiber surfaces which is one of the advantages of introducing GPTMS to Cs chain. The superior antibacterial activity of the produced zinc-containing electrospun fibers of Gelatin-Si-Cs nominate it to be applied for medical purpose.

Improving the performance of Cu2Zn(SnyGe1-y)(SxSe1-x)4 solar cells by CdS:Zn buffer layers

Cu2Zn(SnyGe1-y)(SxSe1-x)4 (CZTGSSe) films were prepared based on a single target sputtering method, then CZTGSSe solar cells were fabricated using CdS:Zn buffer layers which were deposited by adding zinc acetate into the deposition solutions of CdS. For comparison, CZTGSSe solar cells were also fabricated using CdS buffer layers without adding zinc acetate. It is found the CZTGSSe solar cells with CdS:Zn buffer layers perform better than the solar cells with CdS buffer layers. The results reveal that little amount of zinc is incorporated into the buffer layer when zinc acetate is added into the solution. The microstructure and therefore the properties (e.g. Eu energy) are modified by the zinc adding. The solar cells with CdS:Zn buffer layers show alleviated cross-over behavior in J-V measurement, probably because less traps exist in the CdS:Zn buffer layers. The C-V measurement proves that the carrier concentration of the absorber in the solar cell with CdS:Zn buffer layer is slightly lower, and the solar cells with CdS:Zn buffer layers have larger collection depth. These results indicate that the addition of zinc acetate in the deposition solution can not only changes the properties of the buffer layers, but also changes the properties of the absorber layer and the solar cell. The experiment results prove that the CdS:Zn buffer layer would be useful for improving the performances of CZTGSSe solar cells.

Fabrication of stable network-like gold nanostructures in solution and their assessment as efficient NIR-SERS platforms for organic pollutants detection

In this work we report a facile, rapid and low-cost procedure to fabricate network-like gold nanostructures and demonstrate their effectiveness as surface-enhanced Raman scattering (SERS) platforms for organic pollutants detection. The typical procedure starts with the preparation of standard colloidal gold nanoparticles solution followed by addition of zinc acetate which induces formation of novel and useful morphology for SERS substrates. The fabricated plasmonic nanoarchitectures exhibit high stability in water and strong optical enhancing properties in near-infrared (NIR). The NIR-SERS efficiency is assessed against two representative organic dyes, methylene blue and basic fuchsin. The study demonstrates that the as prepared platform can detect minute amounts of organic pollutants in aqueous solution with excitation at 785nm diode laser line from a portable Raman spectrometer. The results are promising for integration in ultrasensitive optical devices for NIR-SERS detection of organic pollutants in watercourses.

Zinc enhances the phototoxic effect of blue light against malodour-producing bacteria in an experimental oral biofilm.

Oral malodour is thought to be caused mainly by the production of volatile sulfide compounds (VSCs) by anaerobic Gram-negative oral bacteria. Previous studies have shown that these bacteria are susceptible to blue light (400-500 nm wavelength). In the present study, we tested the effect of blue light in the presence of zinc, erythrosine B or both on malodour production in an experimental oral biofilm. Biofilms were exposed to a plasma-arc light source for 30, 60 and 120 s (equal to energy fluxes of 41, 82 and 164 J cm(-2), respectively) with or without the addition of zinc acetate, erythrosine B or both. After the light exposure, biofilm samples were examined for malodour production (by an odour judge) and VSC production (with a Halimeter), and VSC-producing bacteria were quantified using a microscopy-based sulfide assay (MSA) and in situ confocal laser scanning microscopy (CLSM). Results showed that exposing experimental oral biofilm to both blue light and zinc reduced malodour production, which coincided with a reduction in VSC-producing bacteria in the biofilm. These results suggest that zinc enhances the phototoxicity of blue light against malodour-producing bacteria.

Comparative evaluation of remineralization, fluoride release and physical properties of conventional GIC following incorporation of 1% and 2% zinc acetate: An in vitro study

Context: Modern concepts of operative dentistry, popularly known as Minimal intervention dentistry, propose that only the infected dentin should be removed, leaving the affected dentine that has the potential to remineralize. Mineralization of the tooth structure left in the cavity is likely to occur due to the application of fluoride- releasing material such as glass ionomer cement (GIC). Aim: The aim of this study was to evaluate whether the remineralizing potential of GIC can be enhanced with the addition of zinc acetate. Study Design: An experimental in vitro intergroup randomized control trial. Materials and Methods: This study consisted of three groups. Group I was conventional GIC, Group II was GIC with 1% zinc acetate and Group III was GIC with 2% zinc acetate. Thirty human premolars (10 in each group) extracted for therapeutic reasons were used in the first part of this study. Standardized class V cavities were prepared on the buccal and lingual surfaces. Teeth were sectioned longitudinally to get one buccal and one lingual half, in which one half was used as the control and the other half was used as the test specimen. Artificial caries- like lesions were produced and subsequently restorations of experimental specimens were performed. The depth of demineralization and remineralization were photographed under a polarized light microscope and quantified using a computerized imaging system. In the second part of the study, fluoride ions released were measured after 24 h and 7 days using an ion sensitive electrode. In the third part of the study, the setting time was calculated using Vicker's apparatus, as the time elapsed from the beginning of mixing till the time when the needle could no more make a circular indentation on the cement. In the fourth part, specimens prepared using Teflon moulds of standardized dimensions were subjected to shear bond strength analysis using a universal testing machine. Statistical Analysis: The obtained results were subjected to statistical analysis using Student's paired and unpaired 't' test, One way ANOVA, Post hoc Tukey's test. Results: In part one of the study, Group III showed the highest amount of remineralization, followed by Group II. All the groups showed statistically highly significant (P < 0.001) zones of remineralization; the difference between the groups was statistically highly significant (P < 0.001) as well. Part two of the study showed that fluoride release was highest in Group III, the difference being statistically highly significant from Group II and Group I at both the time intervals (P < 0.001). However, the amount of fluoride ions released on the 7 th day were lesser than that at 24 h in all the groups (P < 0.001). Parts three and four of the study showed that there was no statistically significant difference between the groups with respect to setting time and shear bond strength (P = 0.82 and 0.64, respectively). Conclusions: Incorporation of zinc acetate to glass ionomer at 2% w/w was effective in enhancing the remineralization property and fluoride release of the cement without affecting its setting time and shear bond strength.

Preparation of Polymer-Metal Composites via In Situ Decomposition of Metal Salts by Frontal Polymerization

Composites containing powdered zinc, and zinc/lead acetate were prepared via frontal polymerization. In the case of the acetates, elemental metal was formed in an in situ decomposition process. The local area function was used to demonstrate the distribution of fillers, and the uniformity of the area fraction for the quantitative characterization of the distribution. With the use of metal acetates, composites of uniform metal distribution can be produced, unlike in systems with metal powder, where the metal particles are enriched at the margin of the sample. It can be established that the specific direct-current resistance significantly decreases in AA-TGDMA composites by the addition of zinc acetate, compared to that of the initial monomer mixture. On heating, the unreacted zinc acetate decomposes further, which results in the further decrease in electrical resistance.

Preparation and characterization of copolyesters of poly(tetramethylene succinate) and poly(butylene terephthalate)

Polymer blends of poly(tetramethylene succinate) (PTMS), a biodegradable aliphatic polyester, and poly(butylene terephthalate) (PBT), a non-biodegradable polyester with aromatic elements, were prepared by melt mixing. Transesterification reactions between both polyesters were promoted by the addition of zinc acetate as a catalyst. The transesterification reaction was evaluated by FT-IR measurements combined with solubility tests and 1 H NMR spectroscopy. The molecular structure of the copolyesters is influenced by the catalyst content and the initial blend composition. Thermal and mechanical properties and the morphology of the resulting material were characterized.

Rheological behavior of styrene‐maleic anhydride/polyol blends obtained through reactive processing

AbstractThe condensation reaction of styrene‐maleic anhydride copolymer (SMAH) with polytetramethylene ether glycol (PTMEG) in the presence or absence of a hydrated zinc acetate catalyst was studied in a batch mixer. As a control, pure SMAH and an SMAH/catalyst blend were also subjected to the same processing conditions. The reaction characteristics of the blends were investigated by Fourier transform infrared spectroscopy (FTIR) and thermal and rheological analysis. FTIR analysis of the SMAH/PTMEG blend indicated ester formation. The addition of zinc acetate and/or PTMEG to SMAH decreased the glass transition temperature of pure SMAH. Oscillatory shear properties of storage modulus, G′, loss modulus, G″, and complex viscosity, η*, were measured. The SMAH/PTMEG/zinc acetate blend had higher G′, G″, and η* than the blend without the zinc acetate catalyst. The parameters of the relaxation spectra were calculated by using the experimental oscillatory data and the generalized Maxwell model. Zero shear viscosity and the mean relaxation time increased with addition of zinc acetate and/or PTMEG to SMAH as a result of chain extension/branching reactions. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 85: 2615–2623, 2002

Encapsulation and stabilization of nerve growth factor into poly(lactic‐co‐glycolic) acid microspheres

The development of a stable sustained‐release formulation of recombinant human nerve growth factor (rhNGF) for the treatment of neuronal diseases is described. The protein was encapsulated into poly(lactic‐co‐glycolic) acid (PLGA) microspheres using a spray freeze drying technique. Liquid nitrogen and cold ethanol were used to spray‐freeze‐dry solid rhNGF that had been suspended in a solution of PLGA dissolved in ethyl acetate. When excipients such as sugar (trehalose), surfactant (pluronic F68), and poly(ethylene glycol) (PEG) were added to the PLGA formulation to protect rhNGF from degradation during spray freeze drying, the protein degraded via aggregation during in vitro release. The formation of an insoluble rhNGF–zinc complex prior to encapsulation into PLGA microspheres stabilized the protein during both microencapsulation and release. In this study, we have demonstrated that the addition of zinc acetate in a 1:12 rhNGF‐to‐zinc acetate molar ratio in a solid rhNGF formulation (4mM sodium bicarbonate at pH 7.4) improves stability of rhNGF during release at 37°C (physiological temperature). The stabilization may be due to rhNGF complexation with zinc to form stable aggregates. The PLGA formulation consisting of 10% rhNGF encapsulated in 12 kDa PLGA (50:50 lactide/glycolide) provided a continuous release of 14 days. The low initial burst (∼1%) and controlled‐release rate were achieved by the addition of 3 or 6% solid zinc carbonate to the polymer phase during microencapsulation. © 2001 Wiley‐Liss, Inc. and the American Pharmaceutical Association J Pharm Sci 90:1356–1365, 2001

In-vitro and In-vivo Efficacy of Zinc Acetate against Propionibacteria Alone and in Combination with Erythromycin

Some studies have been published about the in vitro activity of zinc acetate (ZA), erythromycin (E) and their combination (ZA/E) against Propionibacterium spp., especially erythromycin resistant strains. The efficacy of topical ZA/E combination has been reported as well, but a comparison to ZA monotherapy is missing. Therefore, the MIC values of ZA, E and the ZA/E combination were determined for 15 erythromycin-resistant and 12 erythromycin-sensitive Propionibacterium strains using the agar dilution method and the checkerboard technique. Furthermore, the antimicrobial efficacy of ZA (1.2%) vs. the ZA/E (1.2%/4%) combination in an alcoholic solution was tested in a 7-day treatment administered to 32 acne patients. The MIC 100 for ZA was 1024 micrograms ZA/ml for both, erythromycin resistant and erythromycin sensitive Propionibacterium strains. The ZA, as well as the ZA/E solution showed efficacy reducing both the Propionibacterium spp., and the Micrococcaceae in the sebaceous gland infundibula of acne patients. There was no significant difference between the two treatments. As the MIC 100 of ZA/E was equal to the MIC 100 of ZA, the decrease of the erythromycin MIC of the ZA/E combination in erythromycin-resistant strains may be partly attributed to the addition of ZA to E. The in vivo antibacterial efficacy on 32 acne patients supports the hypothesis that the antibacterial effect of ZA/E in short-term treatment can be mostly attributed to ZA.

Kinetics of glycolysis of polyethylene terephthalate with zinc catalyst

The glycolysis reaction of poly(ethylene terephthalate) (PET) melts with ethylene glycol has been examined in a pressurized reactor. The kinetics of the glycolysis reaction are studied. The rate constants for glycolysis without addition of catalyst are calculated at four different temperatures, yielding an activation energy of 108 kJ mol−1. By comparison, the rate constants for glycolysis with addition of zinc acetate are also calculated at four different temperatures, yielding an activation energy of 85 kJ mol−1. It is found that the activation energy of glycolysis with addition of zinc acetate is lower than that of glycolysis without addition of catalyst. Therefore, zinc acetate has a catalytic effect on PET glycolysis at temperatures between 235 and 275 °C. The effect of catalyst concentration on reaction rate constants is also discussed. Below a critical catalyst concentration, the rate constant for glycolysis is linearly dependent on catalyst concentration. © 1999 Society of Chemical Industry

Internucleosomal DNA fragmentation in ovine luteal tissue associated with luteolysis: in vivo and in vitro analyses.

Internucleosomal DNA fragmentation, a characteristic of apoptosis, can be visualized with agarose gel electrophoresis as discrete low-molecular-weight DNA fragments (laddering), in multiples of approximately 185 bp. CL were collected from superovulated ewes (control) or at 12 h after injection of prostaglandin F2 alpha (PGF2 alpha) on various days after hCG injection. The ability of PGF2 alpha on Days 8, 10, 12, and 14 (n > or = 3 per day per treatment) to induce luteal cell DNA fragmentation was evaluated. DNA was isolated and visualized on agarose gels. No DNA fragmentation was observed in CL from control ewes on Days 8, 10, or 12. Internucleosomal fragmentation of DNA (indicative of apoptosis) as well as nonspecific DNA fragmentation (indicative of non-apoptotic cell death) in CL from Day 14 controls was observed in two of four animals. Additionally, this pattern of DNA fragmentation was observed in CL from ewes treated with PGF2 alpha on all days. Evidence of DNA fragmentation was observed in luteal tissue after dissociation, yet no fragmentation was observed in unsliced, non-dissociated CL collected from Day 10 control ewes (incubated 4 h), or in sliced, non-incubated CL. Slicing and incubation alone were sufficient to initiate DNA fragmentation. A variety of approaches were utilized to inhibit DNA fragmentation. Only the addition of zinc acetate (1 mM) in the incubation medium throughout the 4-h incubation period prevented DNA fragmentation that was initiated by slicing (p < 0.05). There appear therefore, to be one or more intraluteal factors that directly initiate DNA fragmentation associated with cell death in luteolysis.(ABSTRACT TRUNCATED AT 250 WORDS)

Enhancing effect of zinc acetate on the binding of 1-nitropyrene to polydeoxyguanylic-polydeoxycytidylic acid in the hypoxanthine-xanthine oxidase system.

The main aim of this research was to investigate whether conformational alteration of polydeoxyguanylic-polydeoxycytidylic acid (poly[dG-dC].poly[dG-dC]) by zinc acetate would have an effect on the binding of 1-nitropyrene(1-NP) to poly[dG-dC].poly[dG-dC]. The binding of 1-NP to poly[dG-dC].poly[dG-dC] in the hypoxanthine-xanthine oxidase system in vitro was increased by zinc acetate. This increase was abolished when EDTA was added to the preincubated mixture of poly[dG-dC].poly[dG-dC] and zinc ions. Neither the production of 1-aminopyrene and its expected intermediates, N-hydroxy-1-aminopyrene and 1-nitrosopyrene, nor the 1-NP remaining in the reaction mixture was altered by the addition of zinc acetate without poly[dG-dC].poly[dG-dC]. From these findings, it seems that the hypoxanthine-xanthine oxidase system is not activated by zinc acetate. On the other hand, under the same reaction conditions but the hypoxanthine-xanthine oxidase system and 1-NP, it has been reported that zinc ions or complexes transform the B-form of poly[dG-dC].poly[dG-dC] to the Z-form. Therefore, these findings indicate that the formation of the Z-form or intermediates from the B-form by zinc ions may promote the binding of 1-NP to poly[dG-dC].poly[dG-dC].

The enzymic destruction of carotenoids by isolated chloroplasts

Chloroplasts isolated from sugar beet leaves are shown to contain an enzyme which will oxidize carotenoids. This enzyme is inhibited by cyanide and diethyldithiocarbamate. Carotenoid destruction is also inhibited by a number of antioxidants, and stimulated by the addition of zinc acetate and o-phenanthroline to chloroplasts. The enzyme has been extracted from the chloroplasts with sodium deoxycholate and partially purified by fractionation of the extract with ammonium sulphate.

Biliverdin in the Eggs of Nereis fucata

Nereis fucata (Savigny) is a polychaete worm living in the gastropod shells carried by the hermit-crab Eupagurus bernhardus (L.) at Plymouth. The heteronereis or breeding stage found with hermit-crabs during late February was found to contain apparently ripe, blue eggs in the cœlom. The eggs were removed by slitting the body-wall of fresh worms, rinsed in sea water to remove haemoglobin, and separated from cœlomic cells by repeated centrifuging. The pigments in the eggs were extracted into a methanol–sulphuric acid mixture (19 : 1), when a turquoise-blue solution was produced. A purple pigment remained in the eggs; the nature of this pigment is being investigated. The original blue colour of the eggs was apparently due to the mixture of the purple pigment and the turquoise extract. The turquoise solution was filtered through glass wool, diluted with an equal volume of water and shaken with chloroform. The chloroform layer became bluish-green. This was evaporated to dryness in vacuo, and the pigment redissolved in methanol. The absorption spectrum of this solution showed a sharp peak at 392 mµ and a broader peak at 650 mµ, with minimum absorption at 500 mµ. The addition of zinc acetate and iodine produced a brilliant pink fluorescence in ultra-violet light. When more iodine was added the fluorescence became green. The presence of biliverdin was confirmed by the production of a purple colour, with a spectral absorption maximum near 490 mµ, by the addition of concentrated nitric acid, and by the destruction of the blue-green pigment with concentrated sulphuric acid.