On‐Chip Self‐Assembly of a Smart Hybrid Nanocomposite for Antitumoral Applications

A hybrid nanocomposite comprised by porous silicon nanoparticles and a stimuli responsive polymeric material, polyethylene glycol‐block‐poly(L‐histidine), is spontaneously formed by nanoprecipitation in a flow‐focusing microfluidic chip. The nanocomposite presents a novel hybrid compound micelle structure with a great robustness for therapeutic applications. Therefore, the nanocomposite is developed and tested as a “smart” multistage drug delivery system (MDDS) in response to some of the current problems that cancer treatment presents. Based on the stimuli‐responsive behavior of the nanocomposite, a chemotherapeutic agent is successfully loaded into the nanosystem and released upon changes in the pH‐values. The nanocomposite demonstrates enhanced stability in plasma, narrow size distribution, improved surface smoothness, and high cytocompatibility. Furthermore, the nanocomposite presents reduced nanoparticle internalization by phagocytic macrophage cells and pH‐dependent cell growth inhibition capacity. Overall, the developed hybrid nanocomposite shows very promising features for its further development as a “smart” pH‐responsive MDDS.     

Efficient speckle-free laser marking using a spatial light modulator

An approach for laser marking surfaces using a liquid–crystal-based spatial light modulator (LC-SLM) for beam patterning and manipulation is presented, designed to avoid the speckle interference problem which is a typical drawback of current SLM-based laser marking processes. In our approach, the LC-SLM is used to generate complex two-dimensional micropatterns (e.g., 20 × 20 datamatrices) with overall dimensions of < 320 by 320 μm. The micropatterns are generated in a series of 16 steps, using a Fresnel zone lens (FZL) combined with a computer-generated hologram (CGH); for each step the whole kinoform (FZL + CGH) is spatially shifted off-axis by a different amount of pixels to build-up the required pattern. In comparison with other SLM-based laser marking approaches already reported in the literature, our method not only eliminates (or at least significantly reduces) unwanted speckle interference but also reduces the laser power required for marking.     

Controlled oxidation of iron nanoparticles in chemical vapour synthesis

Enteric-coated formulations can delay the release of drugs until they have passed through the stomach. However, high concentration of drugs caused by rapidly released in the small intestine leads to the intestinal damage, and frequent administration would increase the probability of missing medication and reduce the patient compliance. To solve the above-mentioned problems, aspirin-loaded enteric-coated sustained-release nanoparticles with core–shell structure were prepared via one-step method using coaxial electrospray in this study. Eudragit L100-55 as pH-sensitive polymer and Eudragit RS as sustained-release polymer were used for the outer coating and inner core of the nanoparticles, respectively. The maximum loading capacity of nanoparticles was 23.66 % by changing the flow rate ratio of outer/inner solutions, and the entrapment efficiency was nearly 100 %. Nanoparticles with core–shell structure were observed via fluorescence microscope and transmission electron microscope. And pH-sensitive and sustained drug release profiles were observed in the media with different pH values (1.2 and 6.8). In addition, mild cytotoxicity in vitro was detected, and the nanoparticles could be taken up by Caco-2 cells within 1.0 h in cellular uptake study. These results indicate that prepared enteric-coated sustained-release nanoparticles would be a more safety and effective carrier for oral drug delivery.     

2,4,6‐Triarylphosphinines versus 2,4,6‐Triarylpyridines: An Investigation of the Differences in Reactivity between Structurally Related Aromatic Phosphorus and Nitrogen Heterocycles

The novel atropisomeric pyridine derivative rac‐ 10 has been synthesized and structurally characterized. In contrast to its phosphorus analogue 3 , axially chiral 10 has a considerably lower rotational barrier as estimated by DFT calculations. However, the presence of the two enantiomers could be confirmed by means of chiral analytical HPLC analysis and by protonation experiments with a chiral acid. Compound rac‐ 10 could be further dehydrogenated by treatment with DDQ to the benzo(h)quinoline derivative rac‐ 12 . This conversion failed for the phosphorus analogue rac‐ 3 . Interestingly, although 2,4,6‐triarylphosphinines undergo facile C? H activation with [Cp*IrCl₂]₂ in the presence of NaOAc, this reaction does not proceed with the corresponding pyridine derivatives. On the other hand, the latter ones can be selectively ortho‐metalated with Pd(OAc)₂, leading to acetate‐bridged dimeric species, which could be unambiguously confirmed by means of X‐ray crystal structure analysis. The treatment of phosphinines with Pd(OAc)₂ led instead to the formation of the unusual cofacial oxidative coupling products 16 and 17 , which consist of a phosphorus‐containing cage structure.     

Measurement of two solvation regimes in water-ethanol mixtures using x-ray compton scattering

Water-ethanol mixtures exhibit interesting anomalies in their macroscopic properties. Despite a lot of research, the origin of the anomalies and the microscopic structure itself is still far from completely known. We have utilized the synchrotron x-ray Compton scattering technique to elucidate the structure of aqueous ethanol from a new experimental perspective. The technique is uniquely sensitive to the local molecular geometries at the angstrom and subangstrom scales. The experiments reveal two distinct mixing regimes in terms of geometry: the dilute 5 mol % and the concentrated >15 mol % regimes. By comparing with pure liquids, the former regime is characterized by an intramolecular and the latter by an intermolecular change. The findings bring new light to evaluating the hypothesis of formation of clathratelike structures at the dilute concentrations.     

Environmental protection of inkjet-printed Ag conductors

Electrically conductive silver nanoparticle ink patterns were fabricated using the inkjet printing method. Two different polymer films were used as the substrate materials. The patterns were exposed to humidity and salt fog and the electrical performance (sheet resistance and RF performance) as well as mechanical endurance (adhesion) were measured before and after the environmental tests. The electrical properties of the printed structures remained good in all the measurable samples. The adhesion between the ink and a substrate material appeared to be a greater challenge in harsh environments. Protection capabilities of one dip coated and one hot laminated barrier materials were evaluated during the environmental tests. The results showed that there is a need for environmental protection in printed electronics. Especially the laminated barrier films can offer a potential solution for shielding printed electronics in harsh environments as they can provide good mechanical protection, and can easily be integrated in roll-to-roll process.     

Scintillation effects on total fade distributions forEarth-satellite links

Scintillation effects on the cumulative fade distributions for Earth-satellite links are considered. Two combination methods for scintillation and attenuation distributions are compared using filtered and unfiltered 11.2 GHz beacon measurements from Austin, TX, on a 5.8° elevation path. A combination method based on the assumption of independent scintillation and attenuation phenomena is proposed. Attenuation and total fade distributions at 19.8 and 29.7 GHz from Kirkkonummi, Finland, on a 12.7° elevation path, are presented for a summer period. The effects of attenuation and scintillation are also calculated using meteorological data from several radiosonde stations. The calculations show that the relative significance of the scintillation is smaller at frequencies from 20 to 50 GHz than at 12 GHz     

Optimal virtual element patterns for adaptive arrays

A major problem in the use of small arrays is the perturbation in the element patterns due to mutual coupling and diffraction effects. The element patterns differ from each other and need to be corrected in order to obtain an array pattern that is close to the desired one. A matrix method can be used to correct the element patterns by modifying the original input/output weights to corresponding weights for corrected elements and vice versa. In this paper the main goal of the array correction is the maximal identity of the element patterns. In addition to identical element patterns the corrected array is characterized by uniform element spacing, which can be chosen to differ significantly from the element spacing in the real array making the corrected array more like a pure virtual array. For the array correction the linear least square error method has been used. To show the applicability of the virtual array, this method is applied to a typical beam scan case, and also over a frequency band.     

Influence of ethanol on lipid membranes: from lateral pressure profiles to dynamics and partitioning

We have combined experiments with atomic-scale molecular dynamics simulations to consider the influence of ethanol on a variety of lipid membrane properties. We first employed isothermal titration calorimetry together with the solvent-null method to study the partitioning of ethanol molecules into saturated and unsaturated membrane systems. The results show that ethanol partitioning is considerably more favorable in unsaturated bilayers, which are characterized by their more disordered nature compared to their saturated counterparts. Simulation studies at varying ethanol concentrations propose that the partitioning of ethanol depends on its concentration, implying that the partitioning is a nonideal process. To gain further insight into the permeation of alcohols and their influence on lipid dynamics, we also employed molecular dynamics simulations to quantify kinetic events associated with the permeation of alcohols across a membrane, and to characterize the rotational and lateral diffusion of lipids and alcohols in these systems. The simulation results are in agreement with available experimental data and further show that alcohols have a small but non-vanishing effect on the dynamics of lipids in a membrane. The influence of ethanol on the lateral pressure profile of a lipid bilayer is found to be prominent: ethanol reduces the tension at the membrane-water interface and reduces the peaks in the lateral pressure profile close to the membrane-water interface. The changes in the lateral pressure profile are several hundred atmospheres. This supports the hypothesis that anesthetics may act by changing the lateral pressure profile exerted on proteins embedded in membranes.     

Simple model for the growth behaviour of mixed lecithin-bile salt micelles

Mixed lecithin-bile salt micelles are known to have a cylindrical or worm-like structure. We investigated their shape, length, flexibility and cross-sectional structure using small-angle neutron scattering (SANS). A broad range of sample compositions was studied varying both the total amphiphile concentration and the molar ratio of bile salt (sodium taurochenodeoxycholate, NaTCDC) to lecithin (egg yolk phosphatidylcholine, EYL). The length of the micelles was quantitatively linked to the micellar composition by introducing a simple model. The model takes into account the partitioning of lecithin and bile salt between the bulk, cylindrical parts and the end caps of the micelles. The model also sheds light on the organization of the micelles, both in their cylindrical regions and end caps.