IR study on the reaction path of skeletal isomerization of 1‐butene

The reaction molecularity of the skeletal isomerization on zeolite was deduced from IR spectra of adsorbed butene recorded with heating. Formation of polymeric species from adsorbed butene was observed on ZSM‐5 and beta zeolites, non‐selective catalysts for isobutene production. On the other hand, most of butene molecules adsorbed on ferrierite and clinoptilolite behaved monomolecularly, resulting in complete desorption even at ambient temperature. The exceptional selectivity for isobutene of ferrierite and clinoptilolite was ascribed to the sparse distribution of adsorbed butene molecules, suppressing bimolecular oligomerization and enhancing monomolecular skeletal isomerization. This revised version was published online in July 2006 with corrections to the Cover Date.     

Caco-2 cells permeability evaluation of nifuroxazide derivatives with potential activity against methicillin-resistant Staphylococcus aureus (MRSA)

Throughout the period of evaluation and selection in drug development, the assessment of the permeability potential of a compound to achieve an efficient refinement of the molecular structure has been widely appraised by the transport of substances across cell monolayers. This study aims to develop in vitro assays through Caco-2 cells in order to analyze the permeability of 5-nitro-heterocyclic compounds analogues to nifuroxazide with antimicrobial activity, especially showing promising activity against multidrug-resistant Staphylococcus aureus (MRSA). Caco-2 cell monolayers cultivated for 21 days in Transwell® plates were used for the in vitro permeability assays. The quantification of the nifuroxazide derivatives in the basolateral chambers was performed by a validated high performance liquid chromatography with UV (HPLC-UV) method. Apparent permeability values (Papp) show that these compounds can be considered as new drug candidates with the potential to present high absorption in vivo, according to the classifications of Yee and Biganzoli. The thiophenic derivatives showed permeability values higher than the furanic ones, being AminoTIO the compound with the greatest potential for the development of a new drug against MRSA, since it showed the best cytotoxicity, permeability and solubility ratio among all the derivatives.     

Optimal operation of a distributed energy generation system for a sustainable palm oil-based eco-community

The palm oil industry potentially can be environmentally sustainable through utilizing the vast availability of biomass residues from palm oil mills as renewable energy sources. This work addresses the optimal operation of a combined bioenergy and solar PV distributed energy generation system to meet the electricity and heat demands of an eco-community comprising a palm oil mill and its surrounding residential community. A multiperiod mixed-integer linear programming planning and scheduling model is formulated on an hourly basis that optimally selects the power generation mix from among available biomass, biogas, and solar energy resources with consideration for energy storage and load shifting. A multiscenario approach is employed that considers scenarios in the form of many possible weather conditions and various energy profiles under varying mill operation modes and residential electricity consumption. The proposed approach is demonstrated on a realistic case study for a palm oil mill in the Iskandar Malaysia economic development region. The computational results indicate that biomass-based resource is the preferred renewable energy to be implemented due to the high cost associated with solar PV. As well, load shifting and energy storage can be feasibly deployed for demand peak shaving particularly for solar PV systems.     

Prediction of Injured and Dead Inactivated Escherichia coli O157:H7 Cells after Heat and Pulsed Electric Field Treatment with Attenuated Total Reflectance Infrared Microspectroscopy Combined with Multivariate Analysis Technique

Attenuated total reflectance infrared microspectroscopy combined with soft independent modeling of class analogy (SIMCA) multivariate technique was used to differentiate between alive, dead, and injured Escherichia coli O157:H7 cells. E. coli O157:H7 cells were suspended in citrate phosphate buffer at pH 4.0 and 7.0 and treated by heat at 54 °C for 5, 10, 20, and 90 min or pulsed electric field (PEF) at 35 kV/cm for 10, 25, 50, and 60 pulses. The SIMCA analysis confirmed that major contribution to the discrimination of the untreated and treated E. coli cells were (1) the amide I band at 1,638 and 1,618 cm^?1 corresponding to changes in β-pleated secondary protein structure (heat-treated cells at pH 7.0 and 4.0, and PEF-treated cells at pH 4.0), and (2) the bands at 1,078 and 993 cm^?1 corresponding to changes in P?=?O (PO ₂ ^? ) stretching of phosphodiesters or lipopolysaccharides and C–O–C or C–O stretching of different polysaccharides (PEF-treated cells at pH 7.0). The use of partial least squares regression analysis allowed for correctly predicting the survivors of the thermal treatment. Injured cells could be estimated from the comparison of cell counts predicted in nonselective and selective plating media with sodium chloride and bile salts. The prediction results yielded inactivation values with a coefficient of determination (R ²) of 0.83 or higher and a standard error of cross validation between 0.11 and 0.37 log cycles of inactivation.     

Effects of High-Pressure Processing on the Quality of Sea Bass (Dicentrarchus labrax) Fillets During Refrigerated Storage

The aim of this study was to evaluate the effect of high-pressure processing (HPP) on the quality of fresh sea bass fillets using two pressure levels (250 and 400 MPa; 5 min pressure holding time). Vacuum-packed fillets were used as control samples, and all fillets were stored under refrigerated conditions for 18 days. The microbiological, chemical, physical, and sensory parameters were followed. Both HPP treatments increased the microbiological shelf life of sea bass fillets. In day 14, control samples reached the upper acceptability limit (7 log colony-forming units (CFU)?g^?1), while fillets treated at 250 and 400 MPa had 3.2 and 1.4 log CFU g^?1, respectively. In general, hydrogen sulphide-producing bacteria and Enterobacteriaceae loads were below the detection limit in HPP treatments. Results from nucleotide analysis indicate that HPP treatments reduced the conversion of inosine 5′-monophosphate to inosine. HPP also influenced fillet sensory characteristics. The most evident changes in fillets were the increase in whiteness, the loss of translucency, and a firmer consistency. The effect was more pronounced in the treatment at 400 MPa. Lipid oxidation increased in HPP-treated samples, being more accentuated in the treatment at 400 MPa. Instrumental smell intensity increased in both HPP treatments, though the sensory panel did not detect any rancid or other unpleasant odours. No effect was observed in the amount of volatile bases or in pH values. In conclusion, HPP treatments showed potential application for new fish product development with increased microbiological safety and shelf life, longer freshness, and unique characteristics (e.g. firmer and whitish).     

Inulinase from Rhodotorula mucilaginosa: immobilization and application in the production of fructooligosaccharides

The crude extract containing inulinase from Rhodotorula mucilaginosa was obtained by submerged fermentation. Inulinase was immobilized on chicken eggshell by physical adsorption and covalent crosslinking, using glutaraldehyde as a crosslinking reagent, and Celite by adsorption. Fructooligosaccharides production was performed using immobilized inulinase (5%, w/v) and inulin substrate solution under experimental conditions evaluated through Doehlert experimental design. The production of inulinase was optimized for concentrations of D-glucose and yeast extract at 12.5 and 0.5 g/L, respectively, resulting in an optimal activity of 0.62 U. The optimal pH and temperature for enzyme activity were 8.0 and 75 °C, respectively, leading to an optimal activity of 3.54 U. The highest immobilization efficiency (46.27%) was obtained upon immobilization on Celite. Immobilization by adsorption to eggshell allowed for specific activity of 4.15 U/g, and adsorption to Celite resulted in specific activity of 3.70 U/g. The highest titer in fructooligosaccharides was obtained with an initial inulin concentration of 250 g/L (25%, w/v), and a reaction time of 16 h. Hence, immobilized inulinase proved to be a promising catalyst for fructooligosaccharides production since the formulation is performed through a simple, low-cost, and large-scale applicable methodology.

     

Lead, Cadmium and Cobalt (Pb, Cd, and Co) Leaching of Glass-Clay Containers by pH Effect of Food

Recent studies have shown that handcrafted glass-clay containers are a health risk because they can be contaminated by heavy metals, which can be transferred to food, thus reaching the human body to potentially cause illness. Therefore, in the present work, we evaluate the leaching of lead, cadmium, and cobalt from glass-clay containers into two types of food: tomato sauce (salsa), and chickpea puree. The containers were obtained from four regions in the Mexican state of Hidalgo. Repetitive extractions from the containers were carried out to quantify the leaching of the heavy metals into the salsa, the chickpea puree, and acetic acid using the technique proposed by the USFDA. The results show that greater use of the containers leads to more leaching of heavy metals into both types of food and into the acetic acid, with the greatest metal extraction recorded for the Ixmiquilpan vessels. These results indicate that the metals present in the glass-clay containers leach into the food and that increased reuse increases the risk to the people who use them in food preparation.     

Novel varieties of broccoli for optimal bioactive components under saline stress

BACKGROUND: Consumption of broccoli is increasing steadily worldwide because of the interest in its bioactive composition and nutritive value for health promotion. Novel broccoli cultivars to be established under current adverse conditions in production areas (aggressive environmental conditions and saline irrigation waters) need to maintain physical and nutritional quality for consumption and year‐round supply to the markets. The newly introduced cultivars ‘Naxos’ and ‘Parthenon’ have been selected as potential candidates to replace the currently underperforming ‘Nubia’ variety. We aimed to compare the physical and phytochemical quality (glucosinolates, hydroxycinnamic acids, flavonoids, vitamin C and minerals), as well as the in vitro antioxidant capacity of these three cultivars under conditions of environmental stress. RESULTS: ‘Parthenon’ showed equal productivity and nutritional composition to ‘Nubia’, whereas ‘Naxos’ presented in general the best results when compared to ‘Nubia’ and ‘Parthenon’. For phenolic compounds ‘Nubia’ presented the highest contents, although ‘Naxos’ seemed better adapted to saline stress conditions, as suggested by the lowest degree of variation in the contents of healthy phytochemicals, including phenolic compounds, when grown under such conditions. CONCLUSION: ‘Naxos’ broccoli performed best and is a suitable candidate to replace ‘Nubia’ for marketable, nutritive and phytochemical quality, especially in areas of production under adverse conditions as found in Mediterranean southeast Spain (semiarid climate with saline irrigation water). Copyright © 2011 Society of Chemical Industry     

Disposable planar reference electrode based on carbon nanotubes and polyacrylate membrane

In this technical note, we report a new all-solid-state planar reference electrode based on single-walled carbon nanotubes and photocured poly(n-butylacrylate) (poly(nBA)) membrane containing the Ag/AgCl/Cl(-) ion system. Single-walled carbon nanotubes functionalized with octadecylamide (SWCNT-ODA) and deposited by drop-casting onto a disposable screen-printed electrode are an excellent all-solid-state transducer. The novel potentiometric planar reference electrode shows low potential variability (calibration slopes inferior to 2 mV/dec) for a wide range of chemical species (i.e., ions, small molecules, proteins) in a wide calibration range, redox pairs, changes in pH, and changes in ambient light. Potentiometric medium-term signal stability (-0.9 ± 0.2 mV/h) and electrochemical impedance characterization confirm the correct solid contact between the SWCNT-ODA layer and photocured poly(nBA) membrane. Overall, the materials used and the simple fabrication by screen-printing and drop-casting enable a high throughput and highly parallel and cost-effective mass manufacture of the new disposable reference electrode. Moreover, the reference electrode has a long shelf life, a characteristic that can be of special interest in decentralized and multiplexing potentiometric analysis.     

Instrumental phase-based method for Fourier transform spectrometer measurements processing

Phase correction is a critical procedure for most space-borne Fourier transform spectrometers (FTSs) whose accuracy (owing to often poor signal-to-noise ratio, SNR) can be jeopardized from many uncontrollable environmental conditions. This work considers the phase correction in an FTS working under significant temperature change during the measurement and affected by mechanical disturbances. The implemented method is based on the identification of an instrumental phase that is dependent on the interferometer temperature and on the extraction of a linear phase component through a least-squares approach. The use of an instrumental phase parameterized with the interferometer temperature eases the determination of the linear phase that can be extracted using only a narrow spectral region selected to be immune from disturbances. The procedure, in this way, is made robust against phase errors arising from instrumental effects, a key feature to reduce the disturbances through spectra averaging. The method was specifically developed for the Mars IR Mapper spectrometer, that was designed for operation onboard a rover on the Mars surface; the validation was performed using ground and in-flight measurements of the Fourier transform IR spectrometer planetary Fourier spectrometer, onboard the MarsExpress mission. The symmetrization has been exploited also for the spectra calibration, highlighting the issues deriving from the cases of relevant beamsplitter emission. The applicability of this procedure to other instruments is conditional to the presence in the spectra of at least one spectral region with a large SNR along with a negligible (or known) beamsplitter emission. For the PFS instrument, the processing of data with relevant beamsplitter emission has been performed exploiting the absorption carbon dioxide bands present in Martian spectra.