Antibacterial activity of extract and fractions from branches of Protium spruceanum and cytotoxicity on fibroblasts

The crude ethanol extract (CEE) and fractions from branches of Protium spruceanum were subjected to antibacterial and cytotoxicity assays. Compounds of the most active fraction were identified by GC-MS and LC-MS. CEE was active against 19 bacteria and the ethyl acetate fraction (EAF) showed the lowest minimum bactericidal concentration (MBC 0.3–80.0 mg/mL). Through time-kill assay was observed that EAF induced rapid bactericidal effect against Staphylococcus saprophyticus. The cytotoxicity tests against L929 fibroblasts showed great potential of EAF on the treatment of infections caused by five bacteria (MBC < IC₅₀). The results provide in vitro scientific support to the possible application of branches of P. spruceanum as antimicrobial agent that may contribute for treatment of infections.     

Mercury determination by CV-AAS in wastewater and sewage sludge from a stabilization pond system

The mercury concentrations in wastewater and sewage sludge of a stabilization pond system have been evaluated. The system is built by three parallel facultative ponds followed by two systems of three maturation ponds in series. The samples of wastewater and sludge were digested using nitric acid and placed into a Parr-type bomb for 4 h at 110 degrees C. Mercury was measured by Cold Vapour Atomic Absorption Spectrometry (CV-AAS) at 253.7 nm with sodium tetrahydroborate as reductant. The methodologies were checked with an USEPA quality control sample, a standard reference material from NIST and with another method of mineralization (cold mineralization) showing good results. Concentrations of mercury in wastewater between 1.47 +/- 0.75 microgl(-1) have been found at the entrance of the system and 0.74 +/- 0.0 microgl(-1) at the exit, while in sludge the results were between 0.29 +/- 0.12 microgkg(-1) in the facultative pond and 0.04 +/- 0.02 microgkg(-1) in the second maturation pond (exit).     

Development of a new high performance low pressure chromatographic system using a multisyringe burette coupled to a chromatographic monolithic column

A novel combination of high performance low pressure chromatography with multisyringe flow injection analysis is presented. This system comprises a multisyringe module, three low pressure solenoid valves, a monolithic Chromolith Flash RP-18e column and a diode array spectrophotometer. UV detection is carried out at 250 nm. AutoAnalysis software is used for instrumental control and automated data collection. The results obtained with multisyringe liquid chromatography (MSC) were compared with those obtained with a HPLC system using similar conditions. The chromatographic parameters were calculated from a mixture of anthracene and thiourea using a mobile phase containing acetonitrile-water (60:40) at a flow rate of 2 ml min⁻¹. The proposed MSC system has been successfully applied to the determination of amoxicillin, ampicillin and cephalexin using a mobile phase of sodium acetate buffer (pH 6.2, 0.1 mol l⁻¹)-methanol (90:10) at a flow rate of 2 ml min⁻¹. The low-cost, flexibility and simplicity of MSC should be highlighted.     

Using video representations of teaching in practice-based professional development programs

This article explores how video can be used in practice-based professional development (PD) programs to serve as a focal point for teachers’ collaborative exploration of the central activities of teaching. We argue that by choosing video clips, posing substantive questions, and facilitating productive conversations, professional developers can guide teachers to examine central aspects of learning and instruction. We draw primarily from our experiences developing and studying two mathematics PD programs, the Problem-Solving Cycle (PSC) and Learning and Teaching Geometry (LTG). While both programs feature classroom video in a central role, they illustrate different approaches to practice-based PD. The PSC, an adaptive model of PD, provides a framework within which facilitators tailor activities to suit their local context. By contrast, LTG is a highly specified model of PD, which details in advance particular learning goals, design characteristics, and extensive support materials for facilitators. We propose a continuum of video use in PD from highly adaptive to highly specified and consider the affordances and constraints of different approaches exemplified by the PSC and LTG programs.     

Borane-Tetrahydrofuran as a Useful Reagent in the N-Monoalkylation of Amines and Aminoalcohols by Carbonyl Compounds

A new procedure for the high-yield N-monoalkylation of primary aromatic and aliphatic amines is described.     

Nontrivial dynamics induced by a nonlinear Jaynes-Cummings Hamiltonian

The addition of a nonlinear term to the Jaynes-Cummings Hamiltonian induced a nontrivial discrete dynamics for the number of possible transitions of a given order, represented by a Fibonacci series. We describe the physics of the problem in terms of relevant operators which close a semi-Lie algebra under commutation with the Hamiltonian and therefore extending the generalized Bloch equations, already obtained for the linear case, to the nonlinear one. The initial conditions as well as a thermodynamical treatmetn of the problem is analyzed via the maximum entropy principle density operator. Finally, a generalized solution for the time-independent case is obtained and the solution for the field in a thermal state is recovered.     

Zur Verwendung der mehrdimensionalen Normalverteilung in der Statistik

Ohne Zusammenfassung     

Experimental investigation of partial synchronization in coupled chaotic oscillators

The dynamical behavior of a ring of six diffusively coupled R?ssler circuits, with different coupling schemes, is experimentally and numerically investigated using the coupling strength as a control parameter. The ring shows partial synchronization and all the five patterns predicted analyzing the symmetries of the ring are obtained experimentally. To compare with the experiment, the ring has been integrated numerically and the results are in good qualitative agreement with the experimental ones. The results are analyzed through the graphs generated plotting the y variable of the ith circuit versus the variable y of the jth circuit. As an auxiliary tool to identify numerically the behavior of the oscillators, the three largest Lyapunov exponents of the ring are obtained.     

Human cerebrovascular contractile receptors are upregulated via a B-Raf/MEK/ERK-sensitive signaling pathway

Background  

Cerebral ischemia results in a rapid increase in contractile cerebrovascular receptors, such as the 5-hydroxytryptamine type 1B (5-HT_1B), angiotensin II type 1 (AT₁), and endothelin type B (ET_B) receptors, in the vessel walls within the ischemic region, which further impairs local blood flow and aggravates tissue damage. This receptor upregulation occurs via activation of the mitogen-activated protein kinase pathway. We therefore hypothesized an important role for B-Raf, the first signaling molecule in the pathway. To test our hypothesis, human cerebral arteries were incubated at 37°C for 48 h in the absence or presence of a B-Raf inhibitor: SB-386023 or SB-590885. Contractile properties were evaluated in a myograph and protein expression of the individual receptors and activated phosphorylated B-Raf (p-B-Raf) was evaluated immunohistochemically.