Development of a flow system for the determination of cadmium in fuel alcohol using vermicompost as biosorbent and flame atomic absorption spectrometry

In this study a method for the determination of cadmium in fuel alcohol using solid-phase extraction with a flow injection analysis system and detection by flame atomic absorption spectrometry was developed. The sorbent material used was a vermicompost commonly used as a garden fertilizer. The chemical and flow variables of the on-line preconcentration system were optimized by means of a full factorial design. The selected factors were: sorbent mass, sample pH, buffer concentration and sample flow rate. The optimum extraction conditions were obtained using sample pH in the range of 7.3-8.3 buffered with tris(hydroxymethyl)aminomethane at 50 mmol L⁻¹, a sample flow rate of 4.5 mL min⁻¹ and 160 mg of sorbent mass. With the optimized conditions, the preconcentration factor, limit of detection and sample throughput were estimated as 32 (for preconcentration of 10 mL sample), 1.7 μg L⁻¹ and 20 samples per hour, respectively. The analytical curve was linear from 5 up to at least 50 μg L⁻¹, with a correlation coefficient of 0.998 and a relative standard deviation of 2.4% (35 μg L⁻¹, n = 7). The developed method was successfully applied to spiked fuel alcohol, and accuracy was assessed through recovery tests, with recovery ranging from 94% to 100%.     

Validated HPLC method for the standardization of Phyllanthus niruri (herb and commercial extracts) using corilagin as a phytochemical marker

Phyllanthus niruri L., commonly known in Brazil as ‘quebra‐pedra’, has long been used in the treatment of diverse diseases and especially urolithiasis. The therapeutic effects of P. niruri are attributed to various compounds present in the plant, including the hydrolysable tannin corilagin. In the present study, high‐performance liquid chromatography (HPLC‐/PAD) profiles of leaves and commercial extracts of P. niruri were examined and three compounds, found to be present in all of the samples studied, were isolated by open column chromatography over C₁₈ silica gel followed by preparative HPLC. These compounds were identified by nuclear magnetic resonance as corilagin, rutin and ethyl 3,4,5‐trihydroxybenzoate. Corilagin, which has been proposed as a phytochemical marker for P. niruri, was employed as an external standard in the development and validation of a rapid and efficient qualitative and quantitative HPLC assay for the analyte. The method may be applied in the standardization of herbs and phytomedicines commercialized in Brazil as quebra‐pedra. Copyright © 2009 John Wiley & Sons, Ltd.     

Value distribution of the Lerch zeta-function with algebraic irrational parameter. III

We obtain a limit theorem in the sense of weak convergence of probability measures in the space of analytic functions for the Lerch zeta-function with algebraic irrational parameter. Partially supported by the Lithuanian Studies and Science Foundation.     

Energy forms on conformal C1‐diffeomorphic images of the Sierpinski gasket

The energy form on a conformal C¹‐diffeomorphic image G of the Sierpinski gasket K is constructed by integrating the Lagrangian LG on G, which is given in terms of the pullback of the Lagrangian LK on K and of the differential of the diffeomorphism. The extension of this approach to the class of nested fractals is outlined. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Nitrification and denitrification processes for biologic treatment of industrial effluents

Applied Biochemistry and Biotechnology - Nitrification process performance was evaluated using a three-phase fluidized-bed bioreactor. Asynthetic effluent was used for this experiment containing...     

Tutorial on constructing a red blood cell inventory management system with two demand rates

Many countries face the situation where demand for blood products is growing faster than donor recruitment, so the efficient management of available blood supplies is of great economic and social importance. Historically, blood models dealt with two main issues—expiration of blood products with a limited shelf life vs. minimizing blood inventory shortages. Advances in blood storage technologies have resulted in extended shelf lives for some blood products, as well as the ability to use substitute, synthetic blood products at an additional cost. Moreover, prior models do not support multiple demand levels and priorities, where demand for non-urgent blood products can be restricted in event of low inventory levels. The work described in this paper revisits a queuing model and using level crossing techniques, determines an optimal policy to support modeling trade-offs between the following criteria: multiple demand levels (emergency and discretionary), service levels, costs, as well as the traditional objectives of minimizing shortages and expiration (matching supply and demand). Using simulation, the model was compared with current control techniques and demonstrated to be effective using real data obtained from Canadian Blood Services.     

Modeling and simulation of cephalosporin C production in a fed-batch tower-type bioreactor

Immobilized cell utilization in tower-type bioreactor is one of the main alternatives being studied to improve the industrial bioprocess. Other alternatives for the production of β-lactam antibiotics, such as a cephalosporin C fed-batch process in an aerated stirred-tank bioreactor with free cells of Cephalosporium acremonium, or a tower-type bioreactor with immobilized cells of this fungus, have proven to be more efficient than the batch process. In the fed-batch process, it is possible to minimize the catabolite repression exerted by the rapidly utilization of carbon sources (such as glucose) in the synthesis of antibiotics by utilizing a suitable flow rate of supplementary medium. In this study, several runs for cephalosporin C production, each lasting 200 h, were conducted in a fed-batch tower-type bioreactor using different hydrolyzed sucrose concentrations. For this study's model, modifications were introduced to take intoaccount the influence of supplementary medium flow rate. The balance equations considered the effect of oxygen limitation inside the bioparticles. In the Monod-type rate equations, cell concentrations, substrate concentrations, and dissolved oxygen were included as reactants affecting the bioreaction rate. The set of differential equations was solved by the numerical method, and the values of the parameters were estimated by the classic nonlinear regression method following Marquardt's procedure with a 95% confidence interval. The simulation results showed that the proposed model fit well with the experimental data, and based on the experimental data and the mathematical model, an optimal mass flow rate to maximize the bioprocess productivity could be proposed.

     

Updates on softwood-to-ethanol process development

Softwoods are generally considered to be one of the most difficult lignocellulosic feedstocks to hydrolyze to sugars for fermentation, primarily owing to the nature and amount of lignin. If the inhibitory effect of lignin can be significantly reduced, softwoods may become a more useful feedstock for the bioconversion processes. Moreover, strategies developed to reduce problems with softwood lignin may also provide a means to enhance the processing of other lignocellulosic substrates. The Forest Products Biotechnology Group at the University of British Columbia has been developing softwood-to-ethanol processes with SO₂-catalyzed steam explosion and ethanol organosolv pretreatments. Lignin from the steam explosion process has relatively low reactivity and, consequently, low product value, compared with the highvalue coproduct that can be obtained through organosolv. The technical and economic challenges of both processes are presented, together with suggestions for future process development.     

Synthesis and Antimycobacterial Activity of 3-Phenyl-1H-indoles

Tuberculosis has been described as a global health crisis since the 1990s, with an estimated 1.4 million deaths in the last year. Herein, a series of 20 1H-indoles were synthesized and evaluated as in vitro inhibitors of Mycobacterium tuberculosis (Mtb) growth. Furthermore, the top hit compounds were active against multidrug-resistant strains, without cross-resistance with first-line drugs. Exposing HepG2 and Vero cells to the molecules for 72 h showed that one of the evaluated structures was devoid of apparent toxicity. In addition, this 3-phenyl-1H-indole showed no genotoxicity signals. Finally, time-kill and pharmacodynamic model analyses demonstrated that this compound has bactericidal activity at concentrations close to the Minimum Inhibitory Concentration, coupled with a strong time-dependent behavior. To the best of our knowledge, this study describes the activity of 3-phenyl-1H-indole against Mtb for the first time.     

Multicomponent synthesis of benzoxazinones via tandem Ugi/Mitsunobu reactions: an unexpected cine-substitution

A short (2 steps) synthesis of diverse benzoxazinones by coupling the Ugi multicomponent reaction with an intramolecular Mitsunobu substitution is reported. The cyclization step proceeds via an unexpected cine substitution.