Fast method for multielemental analysis of plants and discrimination according to the anatomical part by total reflection X-ray fluorescence spectrometry

Fast and reliable analytical methodologies are required for quality control of plants in order to assure human health. Ultrasound-assisted extraction in combination with total reflection X-ray fluorescence is proposed as a fast and simple method for multielemental analysis of plants on a routine basis. For this purpose, five certified reference materials have been analysed for the determination of P, K, Ca, Cr, Mn, Fe, Ni, Cu, Zn and Pb. Different extractant media (acids and oxidants) were tried. A mixture of diluted HNO₃ + HCl + HF, was selected as the best option for the achievement of complete extractions. Accurate and precise results can be reached in most cases along with a high sample throughput. Different plants (i.e., herbs, spices and medicinal plants) were analysed. Linear discriminant analysis together with the elemental concentrations allowed the differentiation of commercial preparations corresponding to flower, fruit and leaf.     

Ultrasound-promoted cold vapor generation in the presence of formic acid for determination of mercury by atomic absorption spectrometry

A new cold vapor technique within the context of green chemistry is described for determination of mercury in liquid samples following high-intensity ultrasonication. Volatile Hg evolved in a sonoreactor without the use of a chemical reducing agent is carried to a quartz cell kept at room temperature for measurement of the atomic absorption. The mechanism involved lies in the reduction of Hg(II) to Hg(0) by reducing gases formed upon sonication and subsequent volatilization of Hg(0) due to the degassing effect caused by the cavitation phenomenon. Addition of a low molecular weight organic acid such as formic acid favors the process, but vapor generation also occurs from Hg solutions in ultrapure water. The detection limit of Hg was 0.1 microg/L, and the repeatability, expressed as relative standard deviation, was 4.4% (peak height). Addition of small amounts of oxidizing substances such as the permanganate or dichromate anions completely suppressed the formation of Hg(0), which confirms the above mechanism. Effect of other factors such as ultrasound irradiation time, ultrasound amplitude, and the presence of concomitants are also investigated. Some complexing anions such as chloride favored the stabilization of Hg(II) in solution, hence causing an interference effect on the ultrasound-assisted reduction/volatilization process.     

A Generalized Vision-based Stiffness Controller for Robot Manipulators with Bounded Inputs

Generally, stiffness and impedance control schemes require knowledge of the location of any object with which a robot interacts within its workspace; therefore, the integration of a computer vision system within the control loop allows us to know the location of the robot end effector and the object (target) simultaneously. In this paper, a generalized and saturating vision-based stiffness controller with adaptive gravity compensation is presented. The proposed control algorithm is designed to regulate robot-environment interaction in task-space, where the contact force is modeled as a vector of generalized bounded spring-like forces. In order to control nonredundant robots, the proposed controller has a nonlinear proportional-derivative structure with static model-based compensation of gravitational forces, as it includes a regressor-based adaptive term. To support the proposal, the Lyapunov stability analysis of the closed-loop equilibrium vector is presented. Finally, the suitable performance of the proposed scheme was verified by numerical simulations and experimental tests.

     

Detection of Myosin 1g Overexpression in Pediatric Leukemia by Novel Monoclonal Antibodies

Myosin 1g (Myo1g) is a mechanoenzyme associated with actin filaments, expressed exclusively in hematopoietic cells, and involved in various cellular functions, including cell migration, adhesion, and membrane trafficking. Despite the importance of Myo1g in distinct functions, there is currently no monoclonal antibody (mAb) against Myo1g. mAbs are helpful tools for the detection of specific antigens in tumor cells and other tissues. The development of mAbs against targeted dysregulated molecules in cancer cells remains a crucial tool for aiding in the diagnosis and the treatment of patients. Using hybridoma technology, we generated a panel of hybridomas specific for Myo1g. ELISA, immunofluorescence, and Western blot assay results revealed the recognition of Myo1g by these novel monoclonal antibodies in normal and transformed T and B cells. Here, we report the development and application of new monoclonal antibodies against Myo1g for their potential use to detect its overexpression in acute lymphoblastic leukemia (ALL) patients.     

Association of Vitamin D Metabolism Gene Polymorphisms with Autoimmunity: Evidence in Population Genetic Studies

A high prevalence of vitamin D (calcidiol) serum deficiency has been described in several autoimmune diseases, including multiple sclerosis (MS), rheumatoid arthritis (AR), and systemic lupus erythematosus (SLE). Vitamin D is a potent immunonutrient that through its main metabolite calcitriol, regulates the immunomodulation of macrophages, dendritic cells, T and B lymphocytes, which express the vitamin D receptor (VDR), and they produce and respond to calcitriol. Genetic association studies have shown that up to 65% of vitamin D serum variance may be explained due to genetic background. The 90% of genetic variability takes place in the form of single nucleotide polymorphisms (SNPs), and SNPs in genes related to vitamin D metabolism have been linked to influence the calcidiol serum levels, such as in the vitamin D binding protein (VDBP; rs2282679 GC), 25-hydroxylase (rs10751657 CYP2R1), 1α-hydroxylase (rs10877012, CYP27B1) and the vitamin D receptor (FokI (rs2228570), BsmI (rs1544410), ApaI (rs7975232), and TaqI (rs731236) VDR). Therefore, the aim of this comprehensive literature review was to discuss the current findings of functional SNPs in GC, CYP2R1, CYP27B1, and VDR associated to genetic risk, and the most common clinical features of MS, RA, and SLE.     

Photofermentation of tequila vinasses by Rhodopseudomonas pseudopalustris to produce hydrogen

Hydrogen production by photofermentation of tequila vinasses (VT) was studied using Rhodopseudomonas pseudopalustris DSM 123. To the best of our knowledge this is the first report on hydrogen production by photofermentation on VT. Hydrogen production was doubled on VT (260 m$props_value{literPattern}/L) as compared to a synthetic medium. Storing VT changed its chemical composition; however, in photofermentations of a sixty-day old stock, growth and hydrogen production were similar to fresh VT. The periodic displacement of hydrogen with nitrogen resulted in a three-fold increase in both hydrogen and growth of R. pseudopalustris (860 mL H₂/L and 4.5 g/L respectively) as compared to non-displaced headspace. Hydrogen almost doubled at a light intensity of 270 W/m² (2249 mL H₂) as compared to 68 W/m². In dark-light cycles, biomass and hydrogen production were highest with continuous illumination. The potential of VT to produce hydrogen in high amounts using R. pseudopalustris has been demonstrated.     

Quantum dots confined in an organic drop as luminescent probes for detection of selenium by microfluorospectrometry after hydridation: study of the quenching mechanism and analytical performance

Following a preliminary work (Costas-Mora, I.; Romero, V.; Pena-Pereira, F.; Lavilla, I.; Bendicho, C. Anal. Chem.2011, 83, 2388-2393), a quenching mechanism has been established for the selective detection of Se (as selenium hydride) by microfluorospectrometry using CdSe quantum dots (QDs) as luminescent probes stabilized with hexadecylamine and confined in an organic droplet. For this purpose, luminescence, luminescence lifetime, UV-vis absorption, total reflection X-ray fluorescence, transmission electron microscopy, and atomic force microscopy measurements were performed. The presence of stabilizing agents of QDs in the droplet was found to cause a critical effect on both extraction efficiency of selenium hydride in the drop and luminescence quenching. A self-quenching mechanism due to the aggregation of QDs is suggested. Aggregation is thought to occur as a result of the binding between selenide trapped into the organic drop as selenium hydride and Cd(2+) present in the surface of QDs, which in turn, may cause the loss of stabilizing hexadecylamine groups. After full optimization of main variables influencing the luminescent response, the analytical performance was established. A detection limit as low as 0.08 μg L(-1) Se(IV) and a repeatability expressed as relative standard deviation of 4.6% were obtained. The method was validated against CRM NWTM-27.2 lake water, and a recovery study was performed with synthetic seawater. The use of CdSe as luminescent probes in an organic drop may constitute an extremely selective, sensitive, and miniaturized assay for in situ detection of Se(IV) in water.     

Fast determination of arsenic,selenium, nickel and vanadium in fish and shellfish by electrothermal atomic absorption spectrometry following ultrasound-assisted extraction

Ultrasound-assisted extraction of As, Se, Ni and V from fish and shellfish has been applied as a fast and reliable sample pre-treatment method for accurate determination of the four elements by electrothermal atomic absorption spectrometry with Zeeman (As, Se) or Deuterium (Ni, V) background correction. A multivariate optimization approach has been employed for establishing the effect of variables influencing the extraction process. Under suitable conditions, quantitative extractions occurred from a 10 mass sample (particle size <100 μm) suspended in 1.5 mL of acidic extractant (0.5 or 3% v/v HNO₃) and subjected to high intensity ultrasound (50% amplitude; 3 min). The method was successfully validated against the following certified reference materials: NRCC-DORM-2 dogfish muscle, NRCC-DOLT-2 dogfish liver, NRCC-TORT-2 lobster hepatopancreas, NIST-SRM 1566b oyster tissue and BCR 627 tuna fish. The following seafood samples were analyzed: hake (Merluccius merluccius), sole (Solea solea), clam (Venerupis rhomboides), prawn (Panaeus kerathurus), cuttlefish (Sepia officinalis), shrimp (Palaemon elegans), razor shell (Ensis ensis), cockle (Cardium edule), Mussel (Mytilus galloprovincialis), edible crab (Cancer pagurus), meagrin (Lepidorhombus whiffiagonis). The concentration ranges (μg/g, dry weight) for the elements determined were as follows: As (12.6–190), Se (0.73–2.34), Ni (2.94–46) and V (0.82–5.14). The detection limits (LODs), defined as 3s/m (s being the standard deviation of 10 blank and m the slope of the calibration graph), in dry tissue were 0.6, 0.3, 0.2 and 0.4 μg/g for As, Se, Ni and V, respectively. Between-batch precision was expressed as relative standard deviation from three separate extractions was in the range 3–10%.     

Potential applications of recombinant bifidobacterial proteins in the food industry,biomedicine, process innovation and glycobiology

Food Science and Biotechnology - Bifidobacterial proteins have been widely studied to elucidate the metabolic mechanisms of diet adaptation and survival of Bifidobacteria, among others. The use of...