Dewetting and microphase separation in symmetric polystyrene‐block‐polyisoprene diblock copolymer ultrathin films

The kinetics of surface structure evolution in ultrathin films of low‐molecular‐weight polystyrene‐block‐polyisoprene (M_w: 7300 g mol^?1–7300 g mol^?1) diblock copolymer at temperatures below the bulk order‐to‐disorder transition temperature are presented. Films with two different thicknesses were studied as a function of annealing temperature using atomic force microscopy. These film thicknesses enabled the investigation of the competition between microphase separation and dewetting that resulted in two different morphologies: long‐range bicontinuous structures and random holes. Three distinctive stages of structure evolution were observed in bicontinuous structure, with the underlying mechanism compared with spinodal dewetting. Thicker films presented holes on their surfaces upon annealing at elevated temperatures, and kinetics of formation of the holes were discussed. We found that the molecular mobility determined the rates of dewetting, while the microphase separation hardly affected the dewetting process. © 2015 Society of Chemical Industry     

Film thickness in horizontal annular flow

Film thickness in horizontal annular flow in small diameter pipes (8-12 mm) was measured as a function of circumferential position. In addition a simple analytical model for the prediction of the film thickness at the top and bottom of the pipe is proposed.     

Maternal N-Acetyl-Cysteine Prevents Neonatal Hypoxia-Induced Brain Injury in a Rat Model

Perinatal hypoxia is a major cause of infant brain damage, lifelong neurological disability, and infant mortality. N-Acetyl-Cysteine (NAC) is a powerful antioxidant that acts directly as a scavenger of free radicals. We hypothesized that maternal-antenatal and offspring-postnatal NAC can protect offspring brains from hypoxic brain damage.Sixty six newborn rats were randomized into four study groups. Group 1: Control (CON) received no hypoxic intervention. Group 2: Hypoxia (HYP)-received hypoxia protocol. Group 3: Hypoxia-NAC (HYP-NAC). received hypoxia protocol and treated with NAC following each hypoxia episode. Group 4: NAC Hypoxia (NAC-HYP) treated with NAC during pregnancy, pups subject to hypoxia protocol. Each group was evaluated for: neurological function (Righting reflex), serum proinflammatory IL-6 protein levels (ELISA), brain protein levels: NF-κB p65, neuronal nitric oxide synthase (nNOS), TNF-α, and IL-6 (Western blot) and neuronal apoptosis (histology evaluation with TUNEL stain). Hypoxia significantly increased pups brain protein levels compared to controls. NAC administration to dams or offspring demonstrated lower brain NF-κB p65, nNOS, TNF-α and IL-6 protein levels compared to hypoxia alone. Hypoxia significantly increased brain apoptosis as evidenced by higher grade of brain TUNEL reaction. NAC administration to dams or offspring significantly reduce this effect. Hypoxia induced acute sensorimotor dysfunction. NAC treatment to dams significantly attenuated hypoxia-induced acute sensorimotor dysfunction. Prophylactic NAC treatment of dams during pregnancy confers long-term protection to offspring with hypoxia associated brain injury, measured by several pathways of injury and correlated markers with pathology and behavior. This implies we may consider prophylactic NAC treatment for patients at risk for hypoxia during labor.     

Adiabatic flow distribution of gas and liquid in parallel pipes—Effect of additional restrictions

The distribution of gas and liquid among four parallel pipes was studied with and without orifice restrictions. The results show that the two phases may not be equally distributed among the pipes. It is shown that the two-phase flow mixture can “choose” to flow in one, two, three or in all four pipes depending on gas and liquid flow rates, on pipe inclination and on the orifice plate size. Addition of orifice plates expands the region of stability and the range of flow in all four pipes. The experimental results are in reasonable agreement with the analysis.     

Genetically engineered pfabA pfabR bacteria: an electrochemical whole cell biosensor for detection of water toxicity

We describe here a bacterial sensor for electrochemical detection of toxic chemicals. The sensor constitutes recombinant bacteria harboring plasmids encoding the fabA and fabR genes and has high-resolution amperometric response to membrane-damaging chemicals. For example, it can detect phenol at concentrations ranging between 1.6 and 16 ppm within 20 min. The high sensitivity is achieved by using the fabA promoter fused to a reporter gene-encoded beta-galactosidase on a low copy number plasmid, under the control of the FabR repressor. The use of electrochemical whole cell sensors enables sensitive, fast, easy to operate, and cost-effective detection of water toxicity threats.     

Analyses of diverse mammals’ milk and lactoferrin glycans using five pathogenic bacterial lectins

Milk indigested glycans hamper infections by blocking pathogen adhesion to babies’ cells via lectins (sugar-binding proteins). This study describes usage of five pathogenic bacterial lectins and two plant lectins for analyses of alpaca, buffalo, camel, cow, dog, fallow deer, giraffe, goat, horse, human, rabbit, and sheep milks, and also commercial human and cow milk lactoferrins. The lectins used differentially reacted with the 12 milks – most strongly with humans’ ones. Most of them (excluding Pseudomonas aeruginosa galactophilic PA-IL) were also sensitive to the human and cow lactoferrins. The fucophilic bacterial lectins were most sensitive to human lactoferrin, while the mannophilic ones – to the cow’s. The actual function of bacterial lectins in pathogen adhesion and their non-glycosylated structures (evading non-specific interactions) are advantageous for such studies. This study shows the efficiency of the bacterial lectins for milk analyses: differentiating between the diverse milks, estimating their anti-infection potentials, and probing their active glycans.     

Adsorption of diquat, paraquat and methyl green on sepiolite: experimental results and model calculations

Adsorption of the divalent organic cations paraquat (PQ), diquat (DQ) and methyl green (MG) on sepiolite was determined experimentally and investigated with an adsorption model. The largest amounts of DQ, PQ and MG adsorbed were between 100% and 140% of the cation exchange capacity (CEC) of sepiolite. In previous experiments with monovalent organic cations (dyes), the largest amounts of dyes adsorbed were about 400% of the CEC of sepiolite. Consequently, it was proposed that most of this adsorption was to neutral sites of the clay. The large differences between the adsorption of these divalent organic cations and the monovalent dyes may indicate that there is almost no interaction between DQ, PQ and MG and the neutral sites of sepiolite. This assumption was confirmed by infrared (IR) spectroscopy measurements, that did not show changes in the peaks arising from the vibrations of external Si---OH groups of the clay when the divalent organic cations were added. Adsorption results were compared with calculations of an adsorption model that combines the Gouy–Chapman solution and specific binding in a closed system. The model considers cation adsorption on neutral sites of the clay, in addition to adsorption to mono- or divalent negatively charged sites, forming neutral or charged complexes. The model could adequately simulate the adsorption of the divalent organic cations DQ and PQ when added alone, and could yield good fit for the competitive adsorption experiment between the monovalent dye methylene blue and DQ. In competitive adsorption experiments, when total cationic charges exceeded the CEC, monovalent organic cations were preferentially adsorbed on the clay at the expense of the divalent cations.     

Stability of annular flow

A simple transient model using an unsteady state continuity equation and a quasi steady momentum equation is used to analyse the stability of co-current and counter-current annular flows. It is shown that unstable steady state solutions may take place in both cases. Application of the theory is demonstrated for the problem of flooding and flow reversal.     

Novel integrated electrochemical nano-biochip for toxicity detection in water

An electrochemical nano-biochip for water toxicity detection is presented. We describe chip design, fabrication, and performance. Bacteria, which have been genetically engineered to respond to environmental stress, act as a sensor element and trigger a sequence of processes, which leads to generation of electrical current. This novel, portable and miniature device provides rapid and sensitive real-time electrochemical detection of acute toxicity in water. A clear signal is produced within less than 10 min of exposure to various concentrations of toxicants, or to stress conditions, with a direct correlation between the toxicant concentration and the induced current.     

Flow pattern transition for downward inclined two phase flow; horizontal to vertical

Data on the flow pattern transition for gas liquid flow in pipes for downward 0–90° inclination was collected. Mathematical models were developed to predict the flow pattern in the whole range of downward inclination.