Synthesis of Double Hydrophilic Block Copolymers Poly(2-isopropyl-2-oxazoline-b-ethylenimine) and their DNA Transfection Efficiency

Gene delivery is now a part of the therapeutic arsenal for vaccination and treatments of inherited or acquired diseases. Polymers represent an opportunity to develop new synthetic vectors for gene transfer, with a prerequisite of improved delivery and reduced toxicity compared to existing polymers. Here, the synthesis in a two-step's procedure of linear poly(ethylenimine-b-2-isopropyl-2-oxazoline) block copolymers with the linear polyethylenimine (lPEI) block of various molar masses is reported; the molar mass of the poly(2-isopropyl-2-oxazoline) (PiPrOx) block has been set to 7 kg mol⁻¹. Plasmid DNA condensation is successfully achieved, and in vitro transfection efficiency of the copolymers is at least comparable to that obtained with the lPEI of same molar mass. lPEI-b-PiPrOx block copolymers are however less cytotoxic than their linear counterparts. PiPrOx can be a good alternative to PEG which is often used in drug delivery systems. The grafting of histidine moieties on the lPEI block of lPEI-b-PiPrOx does not provide any real improvement of the transfection efficiency. A weak DNA condensation is observed, due to increased steric hindrance along the lPEI backbone. The low cytotoxicity of lPEI-b-PiPrOx makes this family a good candidate for future gene delivery developments.     

The importance of solvent reorganisation in the effect of an ionic liquid on a unimolecular substitution process

Temperature dependent rate studies demonstrate an enthalpic benefit and an entropic cost associated with the change in the rate of a unimolecular substitution process on addition of a high proportion of an ionic liquid, the latter effect being supported by molecular dynamics simulations.     

Hybrid nanocapsules: interactions of ABA block copolymers with liposomes

Amphiphilic ABA triblock copolymers, such as poly(2-methyloxazoline)-block-poly(dimethylsiloxan)-block-poly(2-methyloxazoline) (PMOXA-PDMS-PMOXA), form vesicular structures. Here, the interaction of these ABA molecules with lipids is investigated by electron microscopy, fluorescence spectroscopy, light scattering, and differential scanning calorimetry. Our observations suggest the formation of homogeneous mixed polymer-lipid composites, independent of preparation method, i.e. film hydration, dispersion, or detergent removal. When ABA polymersomes and liposomes are mixed, we observed monomer exchanges on a time scale of minutes. The possibility of forming mixed structures and the exchanges between preformed structures allow the combination of the properties of lipids and polymers such as stability and loading encapsulation capacity.     

Combining player statistics to predict outcomes of tennis matches

^** Email: tbarnett{at}swin.edu.au^*** Email: sclarke{at}swin.edu.au With the growth in sports betting, it is possible to bet, bothbefore and during a match, on a range of outcomes in tennis.This paper shows how the standard statistics published by theATP can be combined to predict the serving statistics to beobtained when two given players meet. These statistics are thenused in a spreadsheet model to predict further match outcomes,such as the length of the match and chance of either playerwinning. These calculations can be updated as the match progresses.The method is demonstrated by focusing on a very long men'ssingles match between Roddick and El Aynaoui played at the 2003Australian Open.     

Digital holographic microscopy: a noninvasive contrast imaging technique allowing quantitative visualization of living cells with subwavelength axial accuracy

We have developed a digital holographic microscope (DHM), in a transmission mode, especially dedicated to the quantitative visualization of phase objects such as living cells. The method is based on an original numerical algorithm presented in detail elsewhere [Cuche et al., Appl. Opt. 38, 6994 (1999)]. DHM images of living cells in culture are shown for what is to our knowledge the first time. They represent the distribution of the optical path length over the cell, which has been measured with subwavelength accuracy. These DHM images are compared with those obtained by use of the widely used phase contrast and Nomarski differential interference contrast techniques.     

When size matters: exploring the potential of aminocyclopropenium cations as head groups in triphenylene-derived ionic liquid crystals in comparison with guanidinium and ammonium units

The influence of the size of a single ionic head group on the mesomorphic properties of hexaalkoxytriphenylenes was investigated by synthesising three derivatives with increasing head group diameter. The derivatives were investigated with optical polarising microscopy (POM), differential scanning calorimetry (DSC) and X-ray scattering (WAXS, SAXS). For the derivative with the small trimethylammonium head group, an enantiotropic mesophase was found. The derivative with the bigger tetramethylguanidine head group only showed a monotropic phase and the derivative with the largest bisdiisopropylaminocyclopropenium head group displayed no liquid crystaline properties at all.     

Gambling your way to New York: A story of expectation

Scenarios 1 and 2 assume the player only plays the one game to turn over the required 10,000. If a player had a good run in the first10,000. If a player had a good run in the first 5,000 turnover in Casino War, he or she may be inclined to switch to 3 Card Stud Poker. Likewise, if a player had a bad run in the first $5,000 turnover in 3 Card Stud Poker, he or she may be inclined to switch to Casino War. A player’s choice to switch between 3 Card Stud Poker and Casino War is dependent on his or her current bankroll and how many hands are left to play to wager the required $5,000 turnover in 3 Card Stud Poker, he or she may be inclined to switch to Casino War. A player’s choice to switch between 3 Card Stud Poker and Casino War is dependent on his or her current bankroll and how many hands are left to play to wager the required 10,000. The minimum bet for both games has always been applied. A player may choose to speed up the process by betting higher than the minimum. This may again depend on the player’s current bankroll and how many hands are left to play. In general, increasing the size of the bankroll in any casino game increases the variance and skewness. This would amount to increasing the probability of losing the initial 200 before wagering the initial200 before wagering the initial 5,000 (i.e., a greater chance of having to deposit more money into the casino account).     

Bis-Thioether-Containing Lipid Chains in Cationic Amphiphiles: Physicochemical Properties and Applications in Gene Delivery

Cationic amphiphiles featuring two thioether functions in each lipid chain of bicatenar cationic amphiphiles are reported here for the first time. The physicochemical properties and transfection abilities of these new amphiphiles were compared with those of already reported analogues featuring either (i) saturated, (ii) unsaturated or (iii) mono-thioether containing lipid chains. The homogeneity of the series of new compounds allowed to clearly underscore the effect of bis-thioether containing lipid chains. This study shows that besides previous strategies based on unsaturation or ramification, the incorporation of two thioether functions per lipid chain constitutes an original complementary alternative to tune the supramolecular properties of amphiphilic compounds. The potential of this strategy was evaluated in the context of gene delivery and report that two cationic amphiphiles (i. e. 4 a and 4 b) can be proposed as new efficient transfection reagents.     

The Influence of Martensitic Intercalations in Magnetic Shape Memory NiCoMnAl Multilayered Films

Hysteresis and transformation behavior were studied in epitaxial NiCoMnAl magnetic shape memory alloy thin films with varying number martensitic intercalations (MIs) placed in between. MIs consists of a different NiCoMnAl composition with a martensitic transformation occurring at much higher temperature than the host composition. With increasing number of intercalations, we find a decrease in hysteresis width from 17 K to 10 K. For a large difference in the layers thicknesses this is accompanied by a larger amount of residual austenite. If the thicknesses become comparable, strain coupling between them dominates the transformation process, which manifests in a shift of the hysteresis to higher temperatures, splitting of the hysteresis in sub hysteresis and a decrease in residual austenite to almost 0%. A long-range ordering of martensite and austenite regions in the shape of a 3D checker board pattern is formed at almost equal thicknesses.     

Exploration of continuous-flow benchtop NMR acquisition parameters and considerations for reaction monitoring

This study focused on fundamental data acquisition parameter selection for a benchtop nuclear magnetic resonance (NMR) system with continuous flow, applicable for reaction monitoring. The effect of flow rate on the mixing behaviors within a flow cell was observed, along with an exponential decay relationship between flow rate and the apparent spin–lattice relaxation time (T1*) of benzaldehyde. We also monitored sensitivity (as determined by signal-to-noise ratios; SNRs) under various flow rates, analyte concentrations, and temperatures of the analyte flask. Results suggest that a maximum SNR can be achieved with low to medium flow rates and higher analyte concentrations. This was consistent with data collected with parameters that promote either slow or fast data acquisition. We further consider the effect of these conditions on the analyte's residence time, T1*, and magnetic field inhomogeneity that is a product of continuous flow. Altogether, our results demonstrate how fundamental acquisition parameters can be manipulated to achieve optimal data acquisition in continuous-flow NMR systems.