A simplified version of the total kjeldahl nitrogen method using an ammonia extraction ultrasound-assisted purge-and-trap system and ion chromatography for analyses of geological samples

The total Kjeldahl nitrogen (TKN) method was simplified by using a manifold connected to a purge-and-trap system immersed into an ultrasonic (US) bath for simultaneous ammonia (NH₃) extraction from many previously digested samples. Then, ammonia was collected in an acidic solution, converted to ammonium (NH₄⁺), and finally determined by ion chromatography method. Some variables were optimized, such as ultrasonic irradiation power and frequency, ultrasound-assisted NH₃ extraction time, NH₄⁺ mass and sulfuric acid concentration added to the NH₃ collector flask. Recovery tests revealed no changes in the pH values and no conversion of NH₄⁺ into other nitrogen species during the irradiation of NH₄Cl solutions with 25 or 40 kHz ultrasonic waves for up to 20 min. Sediment and oil free sandstone samples and soil certified reference materials (NCS DC 73319, NCS DC 73321 and NCS DC 73326) with different total nitrogen concentrations were analysed. The proposed method is faster, simpler and more sensitive than the classical Kjeldahl steam distillation method. The time for NH₃ extraction by the US-assisted purge-and-trap system (20 min) was half of that by the Kjeldahl steam distillation (40 min) for 10 previously digested samples. The detection limit was 9 μg g⁻¹ N, while for the Kjeldahl classical/indophenol method was 58 μg g⁻¹ N. Precision was always better than 13%. In the proposed method, carcinogenic reagents are not used, contrarily to the indophenol method. Furthermore, the proposed method can be adapted for fixed-NH₄⁺ determination.     

Production of Cellulolytic Enzymes by <Emphasis Type="Italic">Aspergillus phoenicis</Emphasis> in Grape Waste using Response Surface Methodology

The production of cellulolytic enzymes by the fungus Aspergillus phoenicis was investigated. Grape waste from the winemaking industry was chosen as the growth substrate among several agro-industrial byproducts. A 2 × 2 central composite design was performed, utilizing the amount of grape waste and peptone as independent variables. The fungus was cultivated in submerged fermentation at 30 °C and 120 rpm for 120 h, and the activities of total cellulases, endoglucanases, and β-glucosidases were measured. Total cellulases were positively influenced by the linear increase of peptone concentration and decrease at axial concentrations of grape waste and peptone. Maximum activity of endoglucanase was observed by a linear increase of both grape waste and peptone concentrations. Concentrations of grape waste between 5 and 15 g/L had a positive effect on the production of β-glucosidase; peptone had no significant effects. The optimum production of the three cellulolytic activities was observed at values near the central point. A. phoenicis has the potential for the production of cellulases utilizing grape waste as the growth substrate.     

Infrared and Raman spectroscopic characterization of the phosphate mineral kosnarite KZr2(PO4)3 in comparison with other pegmatitic phosphates

In this research, we have used vibrational spectroscopy to study the phosphate mineral kosnarite KZr₂(PO₄)₃. Interest in this mineral rests with the ability of zirconium phosphates (ZP) to lock in radioactive elements. ZP have the capacity to concentrate and immobilize the actinide fraction of radioactive phases in homogeneous zirconium phosphate phases. The Raman spectrum of kosnarite is characterized by a very intense band at 1,026?cm^?1 assigned to the symmetric stretching vibration of the PO₄ ^3? ??₁ symmetric stretching vibration. The series of bands at 561, 595 and 638?cm^?1 are assigned to the ??₄ out-of-plane bending modes of the PO₄ ^3? units. The intense band at 437?cm^?1 with other bands of lower wavenumber at 387, 405 and 421?cm^?1 is assigned to the ??₂ in-plane bending modes of the PO₄ ^3? units. The number of bands in the antisymmetric stretching region supports the concept that the symmetry of the phosphate anion in the kosnarite structure is preserved. The width of the infrared spectral profile and its complexity in contrast to the well-resolved Raman spectrum show that the pegmatitic phosphates are better studied with Raman spectroscopy.     

Synthesis and electrochemical evaluation of substituted imidazo[4,5-d]pyrrolo[3,2-f][1,3] diazepine scaffolds

Substituted 4-(2,5-dihydro-1H-pyrrol-3-yl)-1H-imidazoles were prepared from 5-amino-1-aryl-4-cyanoformimidoylimidazoles and cyanoacetamide, under mild experimental conditions. The pyrrolyl-imidazoles were cyclized to the corresponding 7,8-dihydroimidazo[4,5-b]pyrrolo[3,4-d]pyridines by reflux in ethanol, with catalysis by DBU. The same pyrrolyl-imidazoles were reacted with orthoesters, at room temperature and in the presence of sulfuric acid, to generate 3,7-dihydro-8H-imidazo[4,5-d]pyrrolo[3,2-f]diazepines in very good yield. Electrochemical studies of the imidazo[4,5-d]pyrrolo[3,2-f][1,3] diazepine derivatives were carried out. The reduction potential of 7-ethyl-3-(4-methoxyphenyl)-8-oxo-7,8-dihydro-3H-imidazo[4,5-d]pyrrolo[3,2-f][1,3] diazepine-9-carbonitrile was in the adequate range for presenting bioreduction properties.     

Stereoselective synthesis of analogs of the macrolactone of isomigrastatin

An approach for the highly stereoselective synthesis of analogs of the macrolactone of isomigrastatin is described. Our optimized strategy is based on a very efficient lactone opening, a Wittig olefination reaction and a ring closing metathesis. The syntheses were accomplished in 10–11 steps and good overall yields.     

Minimum Evaporation Model of Dermatological Delivery Systems. Lamellar Liquid Crystal Formulations Containing Brazilian Nut (Bertholletia excelsa HBK) Vegetable Oil and Guarana Glycolic Extract

Formulations with lyotropic liquid crystals were prepared from a Brazilian nut vegetable oil, guarana extract and combination of sorbitan monooleate (Span 80) and sorbitan monolaurate ethoxylate EO 20 (Tween 20) in the ratio 1:3 (surfactant component) and their physical–chemical aspects and rheological properties were determined. Compositions with liquid crystals were found in the pseudoternary diagram in a surfactant range of 70–90% and polarized light microscopy, small-angle x-ray scattering (SAXS) showed them to be lamellar. The preparations were furthermore characterized rheologically by shear stress shear rate sweeps finding plastic and pseudoplastic behavior without thixotropy. Electric conductivity and pH measurements demonstrated a potential for future application as dermatological delivery system of the active compounds in the Bertholletia excelsa and Paullinia cupana.      

Bovine lactoferrin purification from whey using Yellow HE‐4R as the chromatographic affinity ligand

The worldwide production of whey increases by around 186 million tons each year and it is generally considered as a waste, even when several whey proteins have important economic relevance. For its valorization, inexpensive ligands and integrated chromatography methods need to be developed for specific and low‐cost protein purification. Here, we describe a novel affinity process with the dye Yellow HE‐4R immobilized on Sepharose for bovine lactoferrin purification. This approach based on a low‐cost ligand showed an efficient performance for the recovery and purification of bovine lactoferrin directly from whey, with a yield of 71% and a purification factor of 61.     

Volatile components of vine leaves from two Portuguese grape varieties (Vitis vinifera L.), Touriga Nacional and Tinta Roriz,analysed by solid-phase microextraction

The purpose of this work was to study the volatile composition of vine leaves and vine leaf infusion prepared from vine leaves collected at 30 and 60 days after grape harvest of two Vitis vinifera L. species. Eighteen volatile compounds were identified by gas chromatography–mass spectrometry in vine leaves and in vine leaf infusions. It was observed that the volatile compounds present in vine leaves are dependent on the time of harvest, with benzaldehyde being the major volatile present in vine leaves collected at 30 days after harvesting. There are significant differences in the volatile composition of the leaves from the two grape cultivars, especially in the sample collected at 60 days after grape harvest. This is not reflected in the volatile composition of the vine leaf infusion made from this two cultivars, the more important being the harvesting date for the volatile profile of vine leaf infusion than the vine leaves grape cultivar.     

Effects of Ultraviolet Radiation (UVA+UVB) and Copper on the Morphology,Ultrastructural Organization and Physiological Responses of the Red Alga Pterocladiella capillacea

The effect of ultraviolet (UV) radiation and copper (Cu) on apical segments of Pterocladiella capillacea was examined under two different conditions of radiation, PAR (control) and PAR+UVA+UVB (PAR+UVAB), and three copper concentrations, ranging from 0 (control) to 0.62, 1.25 and 2.50 μm . Algae were exposed in vitro to photosynthetically active radiation (PAR) at 70 μmol photons m^?2 s^?1, PAR + UVB at 0.35 W m^?2 and PAR +UVA at 0.70 W m^?2 during a 12‐h photocycle for 3 h each day for 7 days. The effects of radiation and copper on growth rates, content of photosynthetic pigments and photosynthetic performance were analyzed. In addition, samples were processed for light and transmission electron microscopy. The content of photosynthetic pigments decreased after exposure to radiation and Cu. Compared with PAR radiation and copper treatments modified the kinetics patterns of the photosynthesis/irradiance curve. The treatments also caused changes in the ultrastructure of cortical and subcortical cells, including increased cell wall thickness and accumulation of plastoglobuli, as well as changes in the organization of chloroplasts. The results indicate that the synergistic interaction between UV radiation and Cu in P. capillacea, led to the failure of protective mechanisms and causing more drastic changes and cellular imbalances.