Chemical, sensory and microbiological changes of gamma irradiated coconut cream powder

A study was carried out to determine optimum decontamination dose for a locally manufactured coconut cream powder. Samples were gamma irradiated (0–15 kGy) and ageing process was achieved using GEER oven at 60 °C for 7 days, which is equivalent to one-year storage at room temperature. Iodine value (IV), ranging from 4.8 to 6.4, was not affected by radiation doses and storage, however peroxide value and thiobarbituric acid (TBA) generally increased with radiation doses. In most samples, peroxide value (meq/kg) reduced after storage, whilst the TBA (mg malonaldehyde/kg), indicator for product quality, slightly increased. The sensory evaluation conducted using 25 taste panellists indicated that scores on odour, creamy taste and overall acceptance for all irradiated samples at more than 5 kGy were significantly lower (P<0.05) than the control. However, the panellists could not detect any significant differences among the irradiation doses (P>0.05). All stored products were significantly different in colour, creamy taste, odour and overall acceptance (P<0.05) when compared to the non-stored non-irradiated control. Microbiological count of the samples prior to irradiation was in the range of 1×10²–1.7×10³ cfu/g with no detection of Salmonella sp. and Escherichia coli. No microbial colonies were detected after irradiation. Based on the TBA and overall sensory acceptance, gamma irradiation of 5 kGy was found to be the optimum dose and lower doses can be considered to decontaminate coconut cream powder.     

Ionic liquid–modified cellulosic hydrogels for loading and sustained release of selenourea: an ensuing inhibition of tyrosinase activity

Cellulose-based hydrogel materials were prepared and modified with tannic acid and l-methionine using ionic liquid as the solvent. The gels were prepared to develop a sustained release medium for selenourea (SeU). The drug delivery characteristics of selenourea-loaded cellulose (CSeU), selenourea-loaded tannic acid-modified cellulose (CTSeU), and selenourea-loaded L-methionine-modified cellulose (CMSeU) were investigated in aqueous media and simulated gastric fluid (SGF) media. This modified gel beads have been characterized using field emission scanning electron microscope, X-ray energy-dispersive spectroscopy, Fourier transform infrared spectroscopy, thermogravimetry–differential thermal analysis and swelling properties and compared with those of the unmodified ones. We also investigated the inhibitory effects of SeU released from these gels on the activity of mushroom tyrosinase. Out of all the gel materials, CTSeU showed maximum SeU release both in water and SGF media. However, tyrosinase inhibitory action in PBS medium was comparable for all the three gel materials.     

Robust interface on ENR-50/TiO2 nanohybrid material based sol-gel technique: Insights into synthesis,characterization and applications in optical

In this work, the sol–gel technique was used to prepare a new organic–inorganic hybrid from Epoxidized Natural Rubber (ENR-50) and Titanium dioxide (TiO₂) by blending different content of titania precursors (10, 30, and 50 wt%) with an ENR-50 matrix. A wide range of analyses was conducted to understand the nature of this hybrid and also to evaluate its potential uses in applications required high refractive index such as micro optical and optoelectronic devices. Results indicated that the ring-opening reaction of epoxide groups in ENR-50 increased with the increase of titania content in the hybrid resulting a strong bonding between titania and ENR-50 through TiOC bond, which was observed in FTIR spectrum at 1027–1028 cm⁻¹. It is also observed a slight decrease in the intensity of the amorphous peak along with a new crystalline peak appeared at 2θ = 23 and 27° due to the crystalline nature of titania. The hybrids showed three thermal degradation steps in the range of temperature 76 to 769 °C due to the existence of the Ti moieties with the mixture of polymer chains, which in turn shifted the T_g at 24.3, 26.9 and 28.1 °C for the hybrid at 10, 30, and 50 wt% TiO₂ compared to the T_g of ENR-50 at −18.4 °C respectively. The morphology of the ENR-50 showed clear changes during of the synthesis of ENR-50/TiO₂ hybrids, these changes were proven by SEM, TEM, and AFM analyses. Uv–Vis results showed that the higher wavelength peak at 293 nm has shifted to 296, 298 and 300 nm for the hybrid at 10, 30, and 50 wt% TiO₂ respectively due to the strong interaction between titania precursors and ENR-50 matrix. Furthermore, the hybrids showed good optical transparency in the visible light range.     

Decontamination of pesticide packing using ionizing radiation

The Brazilian agriculture activities have consumed about 288,000 tons of pesticides per year conditioned in about 107,000,000 packing with weight of approximately 23,000 tons. The discharge of empty plastic packing of pesticides can be an environmental concern causing problems to human health, animals, and plants if done without inspection and monitoring. The objective of this work is to study the ionizing radiation effect in the main pesticides used in Brazil for plastic packing decontamination. Among the commercial pesticides, chlorpyrifos has significant importance because of its wide distribution and extensive use and persistence. The radiation-induced degradation of chlorpyrifos in liquid samples and in polyethylene pack was studied by gamma radiolysis. Packing of high-density polyethylene (HDPE) three layer coextruded, named COEX, contaminated with chlorpyrifos, were irradiated using both a multipurpose Co-60 gamma irradiator and a gamma source with 5000 Ci total activity Gamma cell type. The chemical analysis of the chlorpyrifos was made using a gas chromatography associated to the Mass Spectrometry—GCMS from Shimadzu Model QP 5000. Gamma radiation was efficient for removing chlorpyrifos from the plastic packing, in all studied cases.     

Reaction of carboxamide with Cu2Oisonitrile complex; formation of a new chelated copper(I) complex

Reaction of carboxamides with Cu₂O in the presence of t-butyl isocyanide gave new chelated copper(I) complexes, which probably are formed by the insertion of t-butyl isocyanide into the coppernitrogen bond of copper(I) amide isonitrile complexes, which were initially produced from the carboxamides and Cu₂Ot-butyl isocyanide complex. The same chelated copper(I) complexes were prepared more readily by the reaction of the corresponding N-trimethylsilyl-carboxamides with Cu₂Ot-butyl isocyanide complex. Reactions of the copper(I) complexes thus obtained with alkylating agents, such as alkyl halides, alkyl tosylates and triethyloxonium tetrafluoroborate, also were described.     

Stabilisation of ultra-high molecular weight polyethylene with Vitamin E

Ultra-high molecular weight polyethylene (UHMWPE) has been the material of choice for load-bearing articular components used in total joint arthroplasty in the past 30 years. However, the durability of the whole implant has often been compromised by oxidation of UHMWPE components. Since the use of a suitable, biocompatible stabilizer would minimize this inconvenience, the possibility of adding synthetic Vitamin E to medical grade UHMWPE is currently under investigation.In the present work, medical grade UHMWPE was blended with 0.05, 0.1 or 0.5 w/w% of α-tocopherol and consolidated by compression moulding. Small blocks of reference UHMWPE and of each blend were then gamma irradiated to 30 or 100 kGy. FTIR spectroscopy was used to monitor changes in both the polymer and the additive. Thin sections of virgin and α-tocopherol doped UHMWPE irradiated and unirradiated were aged in a ventilated oven at 90 °C and the kinetic of oxidation was followed by FTIR. In addition, CL-imaging curves were recorded at 180 °C on both irradiated and unirradiated samples.Phenol loss is observed in all the α-tocopherol doped samples upon irradiation. Hypotheses on the rearrangements of the additive structure include the formation of quinonoid products. Nevertheless, all the additive-containing samples exhibit better oxidation resistance compared to the virgin material, indicating stabilizing activity of the α-tocopherol derivatives.     

N-Heterocyclic Olefins as Electron Donors in Combination with Triarylborane Acceptors: Synthesis,Optical and Electronic Properties of D–π–A Compounds

N-heterocyclic olefins (NHOs), relatives of N-heterocyclic carbenes (NHCs), exhibit high nucleophilicity and soft Lewis basic character. To investigate their π-electron donating ability, NHOs were attached to triarylborane π-acceptors (A) giving donor (D)–π–A compounds 1 – 3 . In addition, an enamine π-donor analogue ( 4 ) was synthesized for comparison. UV–visible absorption studies show a larger red shift for the NHO-containing boranes than for the enamine analogue, a relative of cyclic (alkyl)(amino) carbenes (CAACs). Solvent-dependent emission studies indicate that 1 – 4 have moderate intramolecular charge-transfer (ICT) behavior. Electrochemical investigations reveal that the NHO-containing boranes have extremely low reversible oxidation potentials (e.g., for 3 , =−0.40 V vs. ferrocene/ferrocenium, Fc/Fc⁺, in THF). Time-dependent (TD) DFT calculations show that the HOMOs of 1 – 3 are much more destabilized than that of the enamine-containing 4 , which confirms the stronger donating ability of NHOs.     

Purification of plasmid DNA vectors by aqueous two-phase extraction and hydrophobic interaction chromatography

The current study explores the possibility of using a polyethyleneglycol(PEG)-ammonium sulphate aqueous two-phase system (ATPS) as an early step in a process for the purification of a model 6.1 kbp plasmid DNA (pDNA) vector. Neutralised alkaline lysates were fed directly to ATPS. Conditions were selected to direct pDNA towards the salt-rich bottom phase, so that this stream could be subsequently processed by hydrophobic interaction chromatography (HIC). Screening of the best conditions for ATPS extraction was performed using three PEG molecular weights (300, 400 and 600) and varying the tie-line length, phase volume ratio and lysate load. For a 20% (w/w) lysate load, the best results were obtained with PEG 600 using the shortest tie-line (38.16%, w/w). By further manipulating the system composition along this tie-line in order to obtain a top/bottom phase volume ratio of 9.3 (35%, w/w PEG 600, 6%, w/w NH4)2 SO4), it was possible to recover 100% of pDNA in the bottom phase with a three-fold increase in concentration. Further increase in the lysate load up to 40% (w/w) with this system resulted in a eight-fold increase in pDNA concentration, but with a yield loss of 15%. The ATPS extraction was integrated with HIC and the overall process compared with a previously defined process that uses sequential precipitations with iso-propanol and ammonium sulphate prior to HIC. Although the final yield is lower in the ATPS-based process the purity grade of the final pDNA product is higher. This shows that it is possible to substitute the time-consuming two-step precipitation procedure by a simple ATPS extraction.     

Isotachophoretic determination of carboxylic acids in biodegradation samples

In the current study a method of isotachophoretic separation of selected carboxylic acids was developed. The method was used for the determination of carboxylated oligo(ethylene glycol)s and their degradation products in biodegradation tests of PEG 250 DA [a mixture of dicarboxylated oligo(ethylene glycol)s]. Two tests were performed in the studies: the Organization for Economic Cooperation and Development (OECD) screening test and the river water die-away test. Both the biodegradation tests proved relatively fast biodegradation of the studied compounds. In the OECD screening test the biodegradation was faster than in the river water die-away test which can be ascribed to a higher concentration of bacteria in the biodegradation liquor. The minimal sample pretreatment and relatively low cost of analysis by the isotachophoretic method used here make it a good alternative to existing methods of carboxylic acids analysis.     

Sol-gel approach to in situ creation of high pH-resistant surface-bonded organic-inorganic hybrid zirconia coating for capillary microextraction (in-tube SPME)

A novel zirconia-based hybrid organic-inorganic sol-gel coating was developed for capillary microextraction (CME) (in-tube SPME). High degree of chemical inertness inherent in zirconia makes it very difficult to covalently bind a suitable organic ligand to its surface. In the present work, this problem was addressed from a sol-gel chemistry point of view. Principles of sol-gel chemistry were employed to chemically bind a hydroxy-terminated silicone polymer (polydimethyldiphenylsiloxane, PDMDPS) to a sol-gel zirconia network in the course of its evolution from a highly reactive alkoxide precursor undergoing controlled hydrolytic polycondensation reactions. A fused silica capillary was filled with a properly designed sol solution to allow for the sol-gel reactions to take place within the capillary for a predetermined period of time (typically 15-30 min). In the course of this process, a layer of the evolving hybrid organic-inorganic sol-gel polymer got chemically anchored to the silanol groups on the capillary inner walls via condensation reaction. At the end of this in-capillary residence time, the unbonded part of the sol solution was expelled from the capillary under helium pressure, leaving behind a chemically bonded sol-gel zirconia-PDMDPS coating on the inner walls. Polycyclic aromatic hydrocarbons, ketones, and aldehydes were efficiently extracted and preconcentrated from dilute aqueous samples using sol-gel zirconia-PDMDPS coated capillaries followed by thermal desorption and GC analysis of the extracted solutes. The newly developed sol-gel hybrid zirconia coatings demonstrated excellent pH stability, and retained the extraction characteristics intact even after continuous rinsing with a 0.1 M NaOH solution for 24 h. To our knowledge, this is the first report on the use of a sol-gel zirconia-based hybrid organic-inorganic coating as an extraction medium in solid phase microextraction (SPME).