Synthetic dataset of speckle images for fiber optic temperature sensor.

The published data correspond to images of simulated specklegrams, which result from the calculation of the modal interference that occurs in a multimode optical fiber. These have a characteristic pattern due to the constructive or destructive interference between the light modes depending on their phase differences. The specklegram contains valuable information since the propagation of the modes varies according to the influence of some external disturbances, and therefore, the speckle pattern changes. This dataset contains specklegrams that vary according to the temperature. These data have been obtained by simulation using the finite element method (FEM) through the COMSOL multiphysics platform. In the simulation, the vector wave equation is solved, and the refractive index of the fiber is recalculated due to the temperature change. We simulated a 1490 nm wavelength laser, an optical fiber with a core diameter of 50 µm and cladding diameter of 125 µm. The dataset contains specklegrams covering the range of temperatures from 0°C to 120°C in 0.2°C steps.

Computational study of the relative stability of some glass-ionomer cement-forming molecules.

This work is part of a larger study whose main objective was to find a series of promising molecules to be used as glass-ionomer-type materials. The project was divided into 3 successive stages; the results of the first stage have been previously published and were used to continue the study. The molecules evaluated in the second stage were constructed by adding a glycidyl methacrylate molecule to the carboxylic groups of the polyacids selected in the previous stage. The modeling was done using the density functional theory for M06-2X/6-311G(d,p). The results indicate that the addition over the carboxylic groups of the fraction of the molecule, corresponding to itaconic acid, is thermodynamically favored. The final stage was modeled with the M06 functional and consisted of obtaining basic structures of glass-ionomer-type materials, by acid-base reaction between the molecules resulting from the second stage with individual ions of Ca (2 +), Zn (2 +), or Al (+ 3). It was concluded that aluminum atoms generate more compact structures that would correlate with more resistant materials.

Computational study of the thermal decomposition of some oxypropenes.

This work aims at describing the computational study of thermal decomposition reaction of three oxypropenes: 2-(1-methylethoxy)propene, 2-ethoxypropene, and 2-butoxypropene. It was carried out in order to delve into the reaction mechanism proposed in experimental studies. Computational optimization calculations and frequencies of the structures were performed with the M06-2X/6-311+G(d,p) method at different temperatures ranging from 600 to 640 K. The rate constants were calculated with the classical transition state theory, and the values obtained are of the same order as the reported experimental values. The results derived from the population partitioning technique indicate that transition states are symmetrical and the mechanism is concerted and highly synchronous.

Effect of temperature on the formation of acrylamide in cocoa beans during drying treatment: An experimental and computational study.

The aim of this work was to determine the effect of temperature on the formation of acrylamide in cocoa beans during drying treatment by an experimental and computational study, in order to assess the presence of this neoformed compound from postharvest stage. The computational study was conducted on the reaction between fructose, glyoxal from glucose, and on asparagine at the M06-2X/6-31+G(d,p) level, under cocoa bean drying conditions at 323.15 to 343.15 K. The proposed reaction for acrylamide formation consisted of seven steps, which required to progress a via cyclic transition state of the four members. In addition, step III (decarboxylation) was considered to be the rate-determining step. Glucose followed an E1-like elimination and fructose exhibited an E1cb-like elimination. Computational model showed that the reaction of acrylamide formation was favored by fructose rather than glucose. The content of reducing sugars, asparagine and acrylamide in fermented and dried cocoa from two subregions of Antioquia-Colombia, as well as roasted cocoa, were evaluated by UHPLC-C-CAD and UHPLC-QqQ. The concentrations of monosaccharides measured at the end of the fermentation and drying process of cocoa nibs showed greater decreases in the levels of fructose as compared to glucose, supporting the main model hypothesis. Acrylamide formation only occurred in Bajo Cauca due to the presence of both precursors and fast drying time (72 h). Finally, it was possible to find the conditions to which acrylamide can be formed from the drying process and not only from roasting, information that can be used for future control strategies.

Matrix effect on quantification of sugars and mannitol developed during the postharvest of cocoa: an alternative method for traceability of aroma precursors by liquid chromatography with an evaporative detector.

The profile of reducing sugars developed during each stage of the postharvest of cocoa beans is an important quality index; these sugars are found to be one of the main precursors of flavor and neoformed compounds. However, its quantification after extraction from different parts of the bean is a challenge due to the complexity of the matrix. The primary aim of this study was to track the formation of reducing sugars and mannitol in samples obtained from various steps of the fermentation and drying processes of cocoa beans by validating a rapid matrix-corrected chromatographic method utilizing a corona-charged aerosol detector for improved sensitivity. The analytes were extracted from ground cocoa beans by solid phase extraction without a defatting step (20 mg raw fermented and 10 mg dried). The experimental variables influencing the effective detection were evaluated at different temperatures and signal filtering levels. Method validation studies showed an average recovery between 77.8 and 120% for fermented cocoa and between 79.6 and 117.7% for dried cocoa. A linear response was achieved for fructose, glucose, sucrose, and mannitol for a concentration range of 0.1-40 mg/L, and maltose showed linearity in the range of 0.1-70 mg/L. Regression coefficients (R) were 0.9991, 0.9993, 0.9992, 0.9995 and 0.9994, respectively. This method was successfully applied to a clone mix of cocoa from Antioquia, Colombia, to confirm the hydrolysis reaction of sucrose into glucose and fructose during fermentation and drying. A quality indicator of an efficient postharvest process in this study was determined to be a glucose percentage of 0.66% w/w and a fructose percentage of 1.46% w/w, which were higher than the values reported by other studies.

Chemometric approaches for postharvest quality tracing of cocoa: An efficient method to distinguish plant material origin.

The aim of this study was to compare the quality of a mixture of cocoa harvested and fermented in three subregions of Antioquia (Colombia), from the chemometric profile based on multivariate statistical analysis. A mixture of clones CCN-52, ICS-1, FLE-2, and FEC-2 harvested in Bajo Cauca, Uraba and Magdalena Medio were subjected to a spontaneous fermentation. The characterization of raw and well-fermented cocoa was performed through 38 parameters, and results were compared by a Principal Component Analysis (PCA) and a Cluster Analysis (CA), followed by a Principal Factors Analysis (PFA- CA). The CA showed that there are differences among subregions only in raw cocoa from Bajo Cauca. PCA allowed identifying the variability between raw and fermented cocoa in a representative way and these results were consistent with the chemical profile. Besides, the number of parameters to differentiate raw cocoa from different subregions was reduced (11-13 parameters) and it was possible to characterize well fermented cocoa with only 10 parameters of 38. PFA-CA consolidated in three factors a grouping to identify the cocoa quality according to the process or interest of the sensory or functional properties. Factor 1 (cocoa quality indicators with functional properties), Factor 2 (indicators of quality of the beginning of fermentation) and Factor 3 (indicators of quality of well-fermented cocoa) each one with a weight of 39, 35 and 26 respectively.

Understanding the thermal [1s,5s] hydrogen shift isomerization of ocimene.

α-Ocimene, ß-ocimenes and alloocimenes are isomeric monoterpenes occurring naturally as oils within several plants and fruits. These thermally unstable compounds are employed in the pharmaceutical and fine-chemicals industries due to their natural plant defense properties and pleasant odors. In this work, and in the context of a recent revival in attention on the subject, we provide new theoretical insights concerning the nature of the electronic reorganization driving the decomposition of cis-ß-ocimene to alloocimene. Our findings support the experimental proposal of a rearrangement via a six-membered cyclic transition state in a one-step concerted and highly synchronic process.

Ultrafast Ca2+ wave in cultured vascular smooth muscle cells aligned on a micropatterned surface.

Communication between vascular smooth muscle cells (SMCs) allows control of their contraction and so regulation of blood flow. The contractile state of SMCs is regulated by cytosolic Ca2+ concentration ([Ca2+]i) which propagates as Ca2+ waves over a significant distance along the vessel. We have characterized an intercellular ultrafast Ca2+ wave observed in cultured A7r5 cell line and in primary cultured SMCs (pSMCs) from rat mesenteric arteries. This wave, induced by local mechanical or local KCl stimulation, had a velocity around 15 mm/s. Combining of precise alignment of cells with fast Ca2+ imaging and intracellular membrane potential recording, allowed us to analyze rapid [Ca2+]i dynamics and membrane potential events along the network of cells. The rate of [Ca2+]i increase along the network decreased with distance from the stimulation site. Gap junctions or voltage-operated Ca2+ channels (VOCCs) inhibition suppressed the ultrafast Ca2+ wave. Mechanical stimulation induced a membrane depolarization that propagated and that decayed exponentially with distance. Our results demonstrate that an electrotonic spread of membrane depolarization drives a rapid Ca2+ entry from the external medium through VOCCs, modeled as an ultrafast Ca2+ wave. This wave may trigger and drive slower Ca2+ waves observed ex vivo and in vivo.

Mutagenicity and genotoxicity of water treated for human consumption induced by chlorination by-products.

Water used for human consumption may contain mutagens and carcinogens generated during the disinfection process with chlorine. In the study described in this article, the mutagenicity and genotoxicity of water samples taken from the San Cristobal treatment plant in Medellin, Colombia, were evaluated. Short-term mutagenic and genotoxic assays using the Ames test and comet assay, respectively, were employed to examine the genotoxic activity of the extracts of these water samples. Two samples were taken before and after the chlorination process. The treated water samples without chlorination did not show mutagenic effects using the Ames test, while the chlorinated samples produced mutagenic activity in both strains. A dose-response relationship for the comet assay was obtained only in the chlorinated samples. MX (3-chloro-4-[dichloromethyl]-5-hydroxy-2[5H]-furanone), E-MX ([E]-2-chloro-3-[dichloromethyl]-4-oxobutenoic acid), and some trihalomethanes were detected at low concentrations. These concentrations were enough, however, to cause detectable mutagenic and genotoxic activity in the extracts of chlorinated water samples.

Red blood cell permeabilization by hypotonic treatments, saponin, and anticancer avicins.

Plasma membrane permeabilization by saponin and anticancer avicins was studied using light dispersion measurements, since high correlation between light dispersion changes and hemolysis has been demonstrated. Nevertheless, we observed that rat red blood cell swelling in moderately hypotonic media was accompanied by up to 20% decrease of light dispersion, when hemolysis was not yet detectable. Avicin G and avicin D were significantly more efficient than saponin in inducing cytotoxicity in PC3 human prostate cancer cells. We found that the preincubation of avicins with the plasma membrane, but not with the cytosolic fraction of previously lysed red blood cells, completely protected fresh cells against permeabilization. The data suggest that the plasma membrane can tightly bind the avicins, but not the saponin. Using the "osmotic protection" method with 100mOsm PEGs of increasing molecular weight in isotonic media, the size of the pores generated by avicin G and avicin D in the plasma membrane was estimated to be higher than the hydrodynamic radius of PEG-8000. The obtained results indicate that the anticancer activity of avicin G and avicin D could be related, at least partially, to their high ability to permeabilize biological membranes. These data might represent interest for possible applications of these anticancer drugs in vivo.

Kinetic and theoretical study of the chalcones as inhibitors of beta-lactamase enzyme.

Staphyloccoccus aureus, Escherichia coli, Pseudomonas aeruginosa, Klebsiella pneumoniae, Acinetobacter baumannii, Enterobacter cloacae and more bacteria have shown resistance to antibiotics in Colombia, therefore, resistance to antibiotics is a problem that is on increase in Colombia. The resistance mechanism to penicillin antibiotics in these bacteria is the expression of beta-Lactamase enzyme. In order to use the penicillin antibiotics which are still effective against them, we had evaluated 10 chalcones as inhibitors of this enzyme. The most active chalcone showed K(m') = 406.7 microM higher than clavulanic acid that showed K(m') = 211.9 microM at 37 degrees C during 10 h, and using amoxycillin as substrate. The chalcones were better competitive inhibitors because of they allowed the hydrolysis of smaller quantity of amoxycillin than the clavulanic acid, the most active chalcone showed K(cat)/K(M) = 1.398 (minM)(-1) and the clavulanic acid showed K(cat)/K(M) = 2.674 (minM)(-1). The molecular modelling of the Enzyme-chalcones complexes showed that the chalcones with electron-donating groups on ortho, meta position of A ring favour the interaction with the residues Threonine-319, Lysine-67, Serine-64 and Tyrosine-150 of the active site of the enzyme, because of the number and strong of Hydrogen bonds of the chalcones in the active site of the enzyme increase, and therefore the affinity of the chalcones increases too. The electron-donating groups in the chalcones contribute to their inductive effect improving the interaction with the active site of the enzyme because of rising of electrostatic attraction between them.

Hemoglobin precipitation by polyethylene glycols leads to underestimation of membrane pore sizes.

The size of pores formed in the plasma membrane by various substances is frequently determined using polyethylene glycols as osmotic protectants. In this work, we have found that the size of pores formed by saponin in the red blood cell membrane determined by hemolysis versus molecular weight of polyethylene glycol was different to that estimated by light dispersion of cell suspensions. After complete swelling of cells induced by saponin in semiisotonic salt media containing 150 mOsm PEG-4000 or PEG-3000, a significant increase in the light absorbance at 640 nm was developed resulting from the formation of hemoglobin precipitates. Easily sedimenting aggregates were also formed when the supernatant of lysed cells was added to the equiosmotic solutions of polyethylene glycols with molecular weight higher than 1000. We suggest that the real size of large pores could be underestimated due to the phenomenon of hemoglobin precipitation by polyethylene glycols.

Calorimetric and computational study of 3-buten-1-ol and 3-butyn-1-ol. Estimation of the enthalpies of formation of 1-alkenols and 1-alkynols.

The enthalpies of combustion and vaporization of 3-buten-1-ol and 3-butyn-1-ol have been measured by static bomb combustion calorimetry and correlation gas chromatography techniques, respectively, and the gas-phase enthalpies of formation, Delta(f)H degrees (m)(g), have been determined, the values being -147.3 +/- 1.8 and 16.7 +/- 1.6 kJ mol(-1), for 3-buten-1-ol and 3-butyn-1-ol, respectively. High level calculations at the G2 and G3 levels have also been carried out. Relationships between the enthalpies of formation of 1-alkanols, 1-alkenols and 1-alkynols and with the corresponding hydrocarbons have been discussed. From the calculated contributions to Delta(f)H degrees (m)(g) for the substitutions of CH(3) by CH(2)OH, CH(3)CH(2) by CH(2)=CH and CH(3)CH(2) by CH triple bond C, we have estimated the Delta(f)H degrees (m)(g) values for 3-buten-1-ol and 3-butyn-1-ol, in excellent agreement with the experimental ones. Delta(f)H degrees (m)(g) values for 1-alkenols and 1-alkynols up to 10 carbon atoms have also been estimated.