Aggregation of Alcohols Ethoxylates in n-Heptane

The solubility and aggregation process of polyethoxylated non-ionic surfactants, of general formula C _i H_2i+1–(O–CH₂–CH₂) _j –OH with i = 6, 8, 10 and j = 3–6 (C _i EO _j ), in heptane were studied. The aggregation of C _i EO _j surfactants in heptane was investigated by using methylene blue (MB) as an absorption probe. In solutions of MB in the presence of these surfactants in heptane, at concentrations larger than the re-dissolution concentration, the UV bands associated to free MB (A ₁) and MB–EO complex (A ₂) were detected. The ratio of these intensities A ₂/A ₁, was used to study the kinetics of the complex formation in pure surfactant. The value of A ₂/A ₁ depends on the surfactant structure and the media wherein MB is dissolved, being larger in the pure surfactant than in heptane solutions. These results are explained in terms of solvent effect and aggregate structures on the complex formation.

Influence of CTAB on the electrochemical behavior of dopamine and on its analytic determination in the presence of ascorbic acid

This research work concerns the electrochemical study of dopamine and ascorbic acid in the presence of the cationic surfactant cetyltrimethylammonium bromide. From this study is possible to note that the cetyltrimethylammonium bromide greatest influence was on the dopamine, because it disfavors both its oxidation and reduction, thereby giving a smaller heterogeneous rate constant, k ⁰, value than in its absence, provoking that the process tends to irreversibility. On the contrary, for the ascorbic acid case, its oxidation was favored; these effects can influence the separation of the dopamine and ascorbic acid voltammetric signals up to 453 mV. Further, the method could be optimized through differential pulse voltammetry to proceed with the analytic determination of dopamine in the presence of ascorbic acid displaying usable analytic parameters, namely: a linearity range of 0–130 μM, a sensitivity of (6.318 ± 0.002) μA mM^?1, a detection limit of (11 ± 0.1) μM, and a quantification limit of (37 ± 0.2) μM, which made it possible to effect the quantification on a commercial pharmaceutical sample.     

High concentration of phosphorus is a distinctive feature of myelin. An X‐Ray elemental microanalysis study using freeze‐fracture scanning electron microscopy of rat sciatic nerve

We have used rat sciatic nerves submitted to freezing and freeze‐fracture to determine the elemental composition of small domains of the peripheral nerve studied at high resolution by scanning electron microscopy. We found that myelin of Schwann cells is unique in its high content in phosphorus (P) that was more than 10 times higher than P measured in any other cells. This high concentration in P makes myelin chemistry suitable of monitoring at the subcellular level using the herein described methodology. Microsc. Res. Tech. 78:537–539, 2015. © 2015 Wiley Periodicals, Inc.     

A pseudo-transient heat transfer simulation of a continuous casting process,employing the element-free Galerkin method

The present work has been conducted in order to develop a novel solution for the heat transfer problem during the continuous casting of steel billets and blooms, by using the element-free Galerkin method under a pseudo-transient moving cross-section slice approach. The transport laws, non-linear aspects and boundary conditions of the initial value problem have been specified. A detailed explanation concerning the characteristics inherent to the application of the element-free Galerkin method to this problem has also been provided. The feasibility and suitability of this novel approach has been verified by comparison with the numerical techniques proposed and the results reported by other researchers as well as an analytical solution of a simple 1-D alloy solidification problem. The results have revealed that this technique could be used successfully in the pseudo transient moving cross-section solution of the heat transfer problem involved in the continuous casting of blooms and square billets.     

Catalytic activity evaluation for hydrogen production via autothermal reforming of methane

A nickel catalyst (5.75 wt.%) supported on gamma-alumina was evaluated through autothermal reforming of methane (ATR). The reforming process was pointed to hydrogen production, following thermodynamic and stoichiometric predictions. The catalyst was characterised by several methods including atomic absorption spectroscopy (AAS), B.E.T.-N₂, X-ray diffraction (XRD), scanning electron microscope (SEM) and thermal analyses (thermogravimetry, TG; derivate thermogravimetry, DTG; and differential thermal analysis, DTA). Experimental evaluations in a fixed-bed reactor (1023–1123 K, 1.00 bar, 150–400 cm³/min feed) presented methane conversions in the range of 40–65%. The effluent mixtures provided hydrogen yields in the range of 78–84%, carbon monoxide 3–14%, and carbon dioxide 5–18%. High molar H₂/CO ratios, ranging from 8 to 90, were obtained. Operating autothermal conditions (excess of steam, 1023–1123 K, 1.00 bar) provided low coke formation and high hydrogen selectivity (81%) for methane reforming.     

Gene Therapy in HIV‐Infected Cells to Decrease Viral Impact by Using an Alternative Delivery Method

The ability of dendrimer 2G‐[Si{O(CH₂)₂N(Me)₂⁺(CH₂)₂NMe₃⁺(I^?)₂}]₈ (NN16) to transfect a wide range of cell types, as well as the possible biomedical application in direct or indirect inhibition of HIV replication, was investigated. Cells implicated in HIV infection such as primary peripheral blood mononuclear cells (PBMC) and immortalized suspension cells (lymphocytes), primary macrophages and dendritic cells, and immortalized adherent cells (astrocytes and trophoblasts) were analyzed. Dendrimer toxicity was evaluated by mitochondrial activity, cell membrane rupture, release of lactate dehydrogenase, erythrocyte hemolysis, and the effect on global gene expression profiles using whole‐genome human microarrays. Cellular uptake of genetic material was determined using flow cytometry and confocal microscopy. Transfection efficiency and gene knockdown was investigated using dendrimer‐delivered antisense oligonucleotides and small interfering RNA (siRNA). Very little cytotoxicity was detected in a variety of cells relevant to HIV infection and erythrocytes after NN16 dendrimer treatment. Imaging of cellular uptake showed high transfection efficiency of genetic material in all cells tested. Interestingly, NN16 further enhanced the reduction of HIV protein 24 antigen release by antisense oligonucleotides due to improved transfection efficiency. Finally, the dendrimer complexed with siRNA exhibited therapeutic potential by specifically inhibiting cyclooxygenase‐2 gene expression in HIV‐infected nervous system cells. NN16 dendrimers demonstrated the ability to transfect genetic material into a vast array of cells relevant to HIV pathology, combining high efficacy with low toxicity. These results suggest that NN16 dendrimers have the potential to be used as a versatile non‐viral vector for gene therapy against HIV infection.     

Influence of the final ethanol concentration on the acetification and production rate in the wine vinegar process

BACKGROUND: The acetification process needs an overall study of the variables influencing it in order to establish their optimum values. Based on industrial experience and available literature, including a recently proposed model by the authors, among the variables most strongly influencing the acetification process are the ethanol concentration at the time the reactor is unloaded, the unloaded volume and the loading rate. To ensure economically efficient industrial production of vinegar, and to check the predictions of the aforementioned model, the influence of the final ethanol concentration at unloading time on the mean acetification rate and on productivity has been studied in this work. RESULTS: An increase in the final ethanol concentration from 0.5 to 3.5% (v/v) increased the mean overall acetification rate and acetic acid production by 38 and 26%, respectively. The increase was established mainly during the loading phase. CONCLUSIONS: The final ethanol concentration is a key variable for process optimization. If a high rate is desired then a product containing much unused substrate will be obtained, which may be industrially unacceptable. These results suggest the necessity to investigate other possibilities when high values for yield and productivity must to be achieved. Copyright © 2010 Society of Chemical Industry     

New Anacardic Acid‐Inspired Benzamides: Histone Lysine Acetyltransferase Activators

A series of N‐(4‐cyano‐3‐trifluoromethyl‐phenyl)‐2‐ethoxy‐6‐alkyl (and alkenyl) benzamides related to the anacardic acid derivative CTPB have been prepared from 2,6‐dihydroxybenzoic acid with a Suzuki coupling and addition of the anion of 4‐cyano‐3‐trifluoromethylphenylamine to a benzodioxinone as the key steps. In U937 cells, these analogues, in particular 7 c , 7 d , 7 f and 7 j , induced cell‐cycle arrest in the G1 phase, caused apoptosis in about 20 % of the cells, and increased the acetylation levels of H3. These activities correlate with the enzymatic activation of histone lysine acetyltransferases (KATs): CBP and PCAF.     

Influence of different reactor types on Nannochloropsis oculata microalgae culture for lipids and fatty acid production

Greenhouse gases emitted into the atmosphere by burning of fossil fuels cause global warming. One option is obtaining biodiesel. Nannochloropsis oculata was cultured under different light intensities and reactors at 25°C for 21 days with f/2 medium to assess their effects on cell density, lipid, and fatty acids (FAs). N. oculata improved cell density on fed-batch glass tubular reactor (7 L) at 200 μmol E m⁻² s⁻¹, yielding 3.5 × 10⁸ cells ml⁻¹, followed by fed-batch Erlenmeyer flask (1 L) at 650 μmol E m⁻² s⁻¹ with 1.7 × 10⁸ cells ml⁻¹. The highest total lipid contents (% g lipid × g dry biomass⁻¹) were 44.4 ± 0.8% for the reactor (1 L) at 650 μmol E m⁻² s⁻¹ and 35.2 ± 0.2% for the tubular reactor (7 L) at 200 μmol E m⁻² s⁻¹, until twice as high compared with the control culture (Erlenmeyer flask 1 L, 80 μmol E m⁻² s⁻¹) with 21.2 ± 1%. Comparing the total lipid content at 200 μmol E m⁻² s⁻¹, tubular reactor (7 L) and reactor 1 L achieved 35.2 ± 0.2% and 28.3 ± 1%, respectively, indicating the effect of shape reactor. The FAs were affected by high light intensity, decreasing SFAs to 2.5%, and increased monounsaturated fatty acids + polyunsaturated fatty acids to 2.5%. PUFAs (20:5n-3) and (20:4n-3) were affected by reactor shape, decreasing by half in the tubular reactor. In the best culture, fed-batch tubular reactor (7 L) at 200 μmol E m⁻² s⁻¹ contains major FAs (16:0; 38.06 ± 0.16%), (16:1n-7; 30.74 ± 0.58%), and (18:1n-9; 17.15 ± 0.91%).     

Metallic Nanoparticles in Heterogeneous Catalysis

Catalysis Letters - Heterogeneous catalysis is a chemical process achieved at solid–gas or solid–liquid interfaces. Many factors including the particle size, shape and metal-support...