Surface and Biocidal Properties of Gemini Cationic Surfactants Based on Propoxylated 1,6-Diaminohexane and Alkyl Bromides

Two new classes of gemini cationic surfactants—hexanediyl-1,6-bis[(isopropylol) alkylammonium] dibromide {in the abbreviation form: C_nC₆C_n[iPr-OH] and C_nC₆C_n[iPr-OH]₂; alkyl: C_nH_{2n + 1} with n = 9, 10, 12 and 14}—have been synthesized by interaction of alkyl bromides with N,N′-di-(isopropylol)-1,6-diaminohexane and N,N,N′,N′-tetra-(isopropylol)-1,6-diaminohexane. The surface tension, electrical conductivity, and dynamic light scattering (DLS) techniques were used to investigate the aggregation properties of the gemini cationic surfactants in aqueous solution. The formation of critical aggregates at two concentrations in an aqueous solution from obtained gemini cationic surfactants were determined via the tensiometric method. Thus, these gemini cationic surfactants start to form aggregates at concentrations well below their critical micelle concentrations (CMC). The surface properties and the binding degree (β) of the opposite ion were tested against the length of the surfactant hydrocarbon chain and the number of the isopropylol groups in the head group. By applying the DLS technique, it was explored that how the number of isopropylol groups in gemini cationic surfactants with C₁₂H₂₅ chain affects the sizes of micelles at concentrations greater than CMC. It was discovered that the obtained gemini cationic surfactants have a biocidal character.     

PHASE EQUILIBRIUM FOR TERNARY LIQUID SYSTEMS OF WATER CARBOXYLIC ACID CHLORINATED HYDROCARBON: THERMODYNAMIC MODELING THROUGH SERLAS

Liquid-liquid equilibrium data of the solubility (binodal) curves and tie-line end compositions are presented for mixtures of [water (1) + formic acid, or acetic acid, or propanoic acid (2) + chlorobenzene, or 1,2-dichloroethane (3)] at T = 293.2 K and P = 101.3 ± 0.7 kPa. A log-basis approach, SERLAS (solvation energy relation for liquid-associated system), has been proposed to estimate the properties and liquid-liquid equilibrium (LLE) of associated systems containing proton-donating and -accepting and polar components capable of a physical interaction through hydrogen bonding or dipole-dipole interaction. The tie lines were also correlated using the UNIFAC-original model. The reliability of the models has been analyzed against the LLE data with respect to the distribution coefficient and separation factor. The proposed model appears to be an improvement in data fit for the ternary systems, yielding a mean relative error of 10.1% for all the systems considered.     

An on-chip cell culturing and combinatorial drug screening system

A low-cost, convenient and precise drug combination screening microfluidic platform is developed, in which cell culture chambers designed with micropillars integrate with three laminar flow diffusion channels. This platform has several distinct features, including minimum shear stress on cells, biocompatibility, optimum concentration distribution and automatic combinatorial gradient generation, which can potentially speed up the discovery of an effective drug combination for cancer ablations. The presented device can generate two-drug combination gradients at the optimum flow rate of 90 μL/h and can be applied to identify the optimal combination of two clinically relevant chemotherapy drugs. For demonstration, paclitaxel at 0.77 × 10^?3 mg/mL and cisplatin at 0.23 × 10^?4 mg/mL were studied against lung cancer cells (A549). This microfluidic device has the potential to provide a precise and robust screening for anticancer combinational drugs practiced in clinics.     

Converting numerical classification into text classification

Consider a supervised learning problem in which examples contain both numerical- and text-valued features. To use traditional feature-vector-based learning methods, one could treat the presence or absence of a word as a Boolean feature and use these binary-valued features together with the numerical features. However, the use of a text-classification system on this is a bit more problematic—in the most straight-forward approach each number would be considered a distinct token and treated as a word. This paper presents an alternative approach for the use of text classification methods for supervised learning problems with numerical-valued features in which the numerical features are converted into bag-of-words features, thereby making them directly usable by text classification methods. We show that even on purely numerical-valued data the results of text classification on the derived text-like representation outperforms the more naive numbers-as-tokens representation and, more importantly, is competitive with mature numerical classification methods such as C4.5, Ripper, and SVM. We further show that on mixed-mode data adding numerical features using our approach can improve performance over not adding those features.     

Synthesis, Surface Active and Thermodynamic Parameters of Novel Quaternary Ammonium Salts

Reactions of octanol, nonanol, decanol, and dodecanol with epichlorohydrin were carried out in the presence of sodium hydroxide as a catalyst. The synthesized non-ionic surfactants were modified with triethanolamine. Surface activity at the water-air interface and electrical conductivity of the resulting surfactants at 10, 20, 30 and 40?°C were determined and thermodynamic parameters of micellization and adsorption were calculated. It was established that the synthesized quaternary ammonium salts have the ability to localize thin crude oil films on the water surface formed due to spill.     

Synthesis and Characteristics of Dodecyl Isopropylolamine and Derived Surfactants

Dodecyl isopropylolamine has been synthesized on the basis of dodecylamine and propylene oxide. The structure of dodecyl isopropanolamine has been determined by X‐ray diffraction, elemental analysis, IR‐ and NMR‐spectroscopic methods. Ionic surfactants have been synthesized by interaction of dodecyl isopropylolamine with various acids (HCl, HBr, acetic and propionic) and alkyl halides (methyl iodide, ethyl bromide and n‐propyl bromide). Colloidal‐chemical parameters, petroleum‐collecting and petroleum dispersing capacities of the synthesized cationic surfactants have been studied.     

Determination of the energy savings and the optimum insulation thickness in the four different insulated exterior walls

The optimum insulation thickness of the external wall for four cities from four climate zones of Turkey, energy savings over a lifetime of 10 years and payback periods are calculated for the five different energy types and four different insulation materials applied externally on walls. Extruded polystyrene, expanded polystyrene, nil siding and rock wool as wall insulation material are selected. In this study, the net energy cost savings are calculated using the P₁–P₂ method. The results show that energy cost savings vary between 4.2 $/m² and 9.5 $/m² depending on the city and insulation materials. The highest payback period value with 2.25 years in Mersin found by using natural gas as an energy source for heating, while the lowest value is reached by using LPG as an energy source in Bitlis.     

Super porous α-, β-, γ-cyclodextrin cryogels with high active agent loading and controllable release profiles

Cyclodextrins (CDs) are truncated cone-like structures that are natural cyclic oligosaccharides. Here, a simple preparation method for super porous poly(α-CD), poly(β-CD), and poly(γ-CD) cryogels crosslinking with divinyl sulfone at 150%, 100% and 125% mole ratios with respect to the α-CD, β-CD, and γ-CD molecules, respectively, under cryogenic conditions, is reported. The interconnected homogeneous pore distribution of CD-based cryogels with pore sizes in the range of 5–100 μm is confirmed by SEM analysis. The CD-based cryogels weighing 10 mg are determined as hemocompatible with <1% hemolysis ratios and >79% blood clotting indexes; whereas the same materials weighing 1 mg are biocompatible with >75% cell viability on L929 fibroblasts. Additionally, active agent adsorption/delivery efficiencies of CD-based cryogels utilizing two active agents, Bisphenol A (BPA, a carcinogenic compound) and Curcumin (CUR, a polyphenolic compound), are individually evaluated. It was revealed that p(γ-CD) cryogels exhibited the highest active agent loading capacity for BPA, 87 ± 13 mg/g, whereas p(α-CD) cryogels showed the highest loading capacity for CUR, 136 ± 4 mg/g. Moreover, the active agent release from p(α-CD), p(β-CD), and p(γ-CD) cryogel networks at pH 7.4 and 37°C were determined as 40.6 ± 2, 35.3 ± 2, and 34 ± 1 mg/g for BPA, and 1.07 ± 0.2, 1.27 ± 0.1, and 1.37 ± 0.1 mg/g for CUR, respectively, within 96 h.     

Determination of Quality Level in Mass Housing Projects in Turkey

In Turkey, achievement of acceptable levels of quality in the construction sector has long been a problem. Great expenditures of time, money, and resources are wasted each year due to inefficient or nonexistent quality levels prevailing in the industry. The situation is even worse in the case of mass housing projects addressing to low and middle income groups. It is the purpose of this paper to identify the type of deviations resulting in rework in mass housing projects, since construction firms can only increase their profit margins by paying more attention to the deviation types. More importantly, firms can improve their images in the sector and thus, can take new projects. To achieve the objective mentioned above, data have been derived from 400 cases by means of a questionnaire containing 108 questions, and results of this survey were evaluated by several statistical techniques. It is concluded that households are not completely satisfied from the quality of products and/or services delivered within their housing units. In future studies, the causes and costs of the rework should be researched for better understanding the results together with the remedial measures being implemented.