Chemical Profile of the Volatile Constituents and Antimicrobial Activity of the Essential Oils from Croton adipatus, Croton thurifer, and Croton collinus

The aim of this study was to determine the volatile phytochemical constituents and evaluate the antimicrobial activity of the essential oils of the leaves from Croton adipatus, Croton thurifer, and Croton collinus. Essential oils were extracted by hydro-distillation using the Clevenger extractor and the phytochemical analysis was determined by Gas chromatography-Mass Spectrometry (GC-MS). The antimicrobial activity was assessed using the agar diffusion and colorimetric broth microdilution methods against Staphylococcus aureus ATCC 25923, Bacillus subtilis ATCC 6633, Escherichia coli ATCC 25922, Pseudomonas aeruginosa ATCC 9027, and Candida albicans ATCC The essential oils from C. adipatus, C. thurifer, and C collinus had 46, 38, and 35 volatile constituents respectively. The main compounds determined in C. adipatus were β-myrcene (18.34%), while in C. collinus was β-caryophyllene (44.7%), and in C. thurifer was an unknown component (C10H16: 22.38%). Essential oil of C. adipatus showed a MIC against B. subtilis (286.4 µg/mL) and C. albicans (572.8 ± 0 µg/mL); C. thurifer against S. aureus (296.1 ± 0 µg/mL) and B. subtilis (148 ± 0 µg/mL); and C. collinus against B. subtilis (72 ± 0 µg/mL) and C. albicans (576.2 ± 0 µg/mL). The three essential oils of Croton species demonstrated in vitro antimicrobial activity against a strain of bacteria or fungi.

Taxonomy of Dark Energy Models

The accelerated expansion of the Universe is one of the main discoveries of the past decades, indicating the presence of an unknown component: the dark energy. Evidence of its presence is being gathered by a succession of observational experiments with increasing precision in its measurements. However, the most accepted model for explaining the dynamic of our Universe, the so-called Lambda cold dark matter, faces several problems related to the nature of such energy component. This has led to a growing exploration of alternative models attempting to solve those drawbacks. In this review, we briefly summarize the characteristics of a (non-exhaustive) list of dark energy models as well as some of the most used cosmological samples. Next, we discuss how to constrain each model’s parameters using observational data. Finally, we summarize the status of dark energy modeling.

Calibration Methods to Circumvent Unknown Component Spectra for Quantitative in situ Raman Monitoring of Co-Polymerisation Reaction

The use of Raman spectroscopy for reaction monitoring has been successfully applied over the past few decades. One complication in such usage is the applicability for quantitative reaction studies. This...

Searching for periodic variations in radial velocities after the removal of orbital motions of spectroscopic binaries

ABSTRACT This study focuses on periodic variations of radial velocities (RVs) after removing the orbital motion of 33 spectroscopic binaries. The RVs were monitored from 2003 to 2012 and published in Katoh et al. (2013, AJ, 145, 41). Their RV precision was determined to be ∼10 m s−1 utilizing an I2 cell. We investigated the periodic variation using a generalzied Lomb–Scargle algorithm and found periodic variations in the residual velocities of seven binary systems. The residual-velocity variations are mostly generated by stellar activity rather than the orbital motion of a possible companion. For eight binaries, we found significant evidence of a second signal, with velocity dispersions greater than three times the RV uncertainty. We find these residual-velocity variations inconsistent with a Doppler signal induced by the orbital motion of an unknown component. For the remaining 18 binaries, we did not detect significant variations of residual-velocity.

The motion and distribution of the gas in the central 300 pc of the galaxy as revealed by spectra of H 3 +

Spectroscopy of absorption lines of H 3 + in the central molecular zone (CMZ) of the Galaxy show that a previously largely unknown component of the interstellar medium there, warm ( T ∼200 K) and diffuse ( n ≲ 10 2 cm −3 ) gas, makes up a large fraction of the volume of the CMZ, and that this gas is moving radially outward from the centre. These discoveries upend the generally accepted understanding that the interstellar environment of the CMZ comprises almost entirely an ultra-hot plasma and dense molecular clouds. The radial momentum associated with the diffuse gas in the CMZ exceeds that of the ejecta of thousands of core-collapse supernovae and implies some extraordinary past activity in the centre, possibly associated with the supermassive black hole, Sgr A*. We speculate that within approximately 10 6 years, gravity could halt the expansion of the diffuse gas and that contraction towards the centre could then commence. This article is part of a discussion meeting issue ‘Advances in hydrogen molecular ions: H 3 + , H 5 + and beyond’.

Collection and identification of an unknown component from Eugenia uniflora essential oil exploiting a multidimensional preparative three-GC system employing apolar, mid-polar and ionic liquid stationary phases

MDGC-Prep is used in combination with NMR, GC-FTIR and GC-MS analyses for the structure elucidation of an unknown component from Eugenia uniflora L. essential oil.

An unknown component of a selective and mild oxidant: structure and oxidative ability of a double salt-type complex having κ1O-coordinated permanganate anions and three- and four-fold coordinated silver cations

A compound having redox-active permanganate and complexed silver ions with reducing pyridine ligands is used as a mild organic and as a precursor for nanocatalyst synthesis in a low-temperature solid-phase quasi-intramolecular redox reaction.

Productive strategies for development of specific mathematical competences for numbers and operation with them in the primary school

The application of productive strategies in education in mathematics facilitates development of specific mathematical competences in the Grade 1-4 students regarding natural numbers and operation with them. Subject of this article is presentation of the concepts about: competences, specific objective mathematical competences and the options for their development in and through education in mathematics in Primary School. A methodology system for work both with productive strategies, approaches, methods and with reproductive such strategies was created. This system is currently being applied in the educational process in mathematics. During the experimental work a longitudinal quality and quantity research of the above topics was performed. The conclusions of the research was that as a result of the experimental work the percentage of the students who made mistakes in writing down and comparing natural numbers decreased. The same can be said for the students who made mistakes during the arithmetical operations addition, subtraction, multiplication and division as well as mistakes in finding unknown component in a concrete equation. It was confirmed that as a result of the experimental work the specific mathematical competences related to the area of competency “Numbers” were developed in the primary school students in their completeness.

Application of the Solution Structure Method in Numerically Solving Poisson’s Equation on the Basis of Atomic Functions

This paper summarizes the main principles of the solution structure method and presents it in combination with atomic basis functions and a collocation technique. The solution of a boundary value problem is expressed in the form of formulae called solution structures, which depend on three components: the first component describes the geometry of the domain exactly in the analytical form, the second describes all boundary conditions exactly, and the third component, that contains information about the differential equation, is the unknown component represented by a linear combination of atomic basis functions. The proposed method is applied to solve the torsion problem.

Chemical light sticks as bait to trap predaceous aquatic insects: effect of light colour

We measured the efficiency of floating minnow-traps (Gee traps), unbaited or baited with red, green, blue, or white chemical light sticks (glowsticks) to trap large, predaceous, aquatic beetles (Coleoptera) and bugs (Hemiptera) in 50 fresh water, lentic systems in northern Nova Scotia, Canada. Standard minnow-traps buoyed with Styrofoam® floats were set overnight in a variety of freshwater habitats, including ponds, marshes, bog pools and vegetated lake margins throughout the ice-free seasons over three years, for a total of 695 trap-nights. Giant Water Bugs (Lethocerus americanus) were captured with equal frequency in traps baited with any colour glowstick and in unbaited controls. Brown Waterscorpions (Ranatra fusca) were significantly more abundant in light-baited traps than in dark controls, and showed a strong preference for green lures over other colours. The large, Vertical Diving Beetle Dytiscus verticalis was caught significantly more than expected with white or red lures and significantly less with green or blue lures; males were caught even less often with green or blue lures than in unbaited controls. Our results reveal a heretofore unknown component of the biology of these insects, and suggest a novel method for simple and effective sampling of aquatic insects in still waters.Keywords: light; trapping; phototaxis; aquatic insects; colour