Structure and Dissolution of l-Leucine-Coated Salbutamol Sulphate Aerosol Particles

L-Leucine formed different crystalline coatings on salbutamol sulphate aerosol particles depending on the saturation conditions of L-leucine. The work emphasizes a careful characterization of powders where structural compartments such as crystal size and particle coating may affect the performance of drug when administered. The sublimation of L-leucine from the aerosol particles took place 90°C lower temperature than the bulk L-leucine which was attributed to result from the sublimation of L-leucine from nano-sized crystalline domains. The dissolution slowed down and initial dissolution rate decreased with increasing L-leucine content. Decreasing crystalline domains to nano-scale improve heat and mass transfer which was observed as the lowered decomposition temperature of the drug salbutamol sulphate and the sublimation temperature of surface material L-leucine as well as the altered dissolution characteristics of the drug. The structure of the coated drug particles was studied by means of thermal analysis techniques (DSC and TG), and the dissolution of salbutamol sulphate was studied as an on-line measurement in a diffusion cell.     

In Situ Probing the Crystallization Kinetics in Gas-Quenching-Assisted Coating of Perovskite Films

The pursuit of commercializing perovskite photovoltaics is driving the development of various scalable perovskite crystallization techniques. Among them, gas quenching is a promising crystallization approach for high-throughput deposition of perovskite films. However, the perovskite films prepared by gas-quenching assisted blade coating are susceptible to the formation of pinholes and frequently show inferior crystallinity if the interplay between film coating, film drying, and crystallization kinetics is not fully optimized. That arguably requires a thorough understanding of how single processing steps influence the crystallization kinetics of printed perovskite films. Here, in situ optical spectroscopies are integrated into a doctor-blading setup that allows to real-time monitor film formation during the gas-quenching process. It is found that the essential role of gas quenching treatment is in achieving a smooth and compact perovskite film by controlling the nucleation rate. Moreover, with the assistance of phase-field simulations, the role of excessive methylammonium iodide is revealed to increase grain size by accelerating the crystal growth rate. These results show a tailored control of crystal growth rate is critical to achieving optimal film quality, leading to fully printed solar cells with a champion power conversion efficiency of 19.50% and mini solar modules with 15.28% efficiency are achieved.     

Seed enhancement: getting seeds restoration‐ready

Seed enhancement technologies such as seed priming and seed coating, developed by the agricultural seed industry, are standard procedures for the majority of crop and horticultural seeds. However, such technologies are only just being evaluated for native plant seeds despite the potential benefits of such treatments for improving restoration effectiveness. Key approaches applicable to native seed include: (1) seed priming, where seeds are hydrated under controlled conditions, and (2) seed coating, in which external materials and compounds are applied onto seeds through a diversity of treatments. These technologies are commonly employed to accelerate and synchronize germination and to improve seed vigor, seedling emergence, establishment, and to facilitate mechanized seed delivery to site, through standardizing seed size and shape. Seed enhancement technologies have now been tested on native seeds to overcome logistical and ecological barriers in restoration. However, further research is needed to extend the application of seed enhancements to a broader array of species, ecosystems, and regions as well as to evaluate new and innovative approaches such as the incorporation of beneficial soil microorganisms and plant growth regulators in the coatings. As techniques in native seed enhancement develop, these approaches need to be capable of being scaled‐up to provide the tonnages of seed required for global restoration.     

Studies on the Polymorphism of l-Glutamic Acid

The β-crystal formation of l-glutamic acid in the seeded solution was investigated; and it was found that the growth rate of the seed crystals in a-axis direction was nearly as large as that of the α-crystal, but the growth rate in b- and c-axes was little recognized. The activation energy of the crystallization process of the β-crystal in a-axis direction was calculated from the growth rate constants determined at various temperatures, and 6~7 kcal/mol was obtained. On the assumption that the crystallization of β-crystal growth was controlled by the diffusional operation, the thickness of the laminar film was calculated from the growth rate constant and the estimated value of the diffusional constant. The calculated value of the thickness was much greater than the value reported by Nernst; therefore, the crystallization process should be controlled by the surface reaction. The co-existence of a small quantity of amino acids caused a great reduction in the growth rate of the β-crystal.     

Surface Layering and Supersaturation for Top‐Down Nanostructural Development during Spin Coating of Polymer/Fullerene Thin Films

This study provides new evidence on a long postulated mechanism of phase separation in a polymer/fullerene mixture during spin coating for controlled nanodomains of oriented crystallization and heterojunctions that favor applications in polymer solar cells (PSCs). The simultaneous nanoscale phase separation and crystallization during spin coating of the mixture are traced using in situ grazing‐incidence small‐ and wide‐angle X‐ray scattering. Combined with the complimentary results from time‐resolved optical reflectance spectroscopy, transient stratification of the liquid film during the transition from the flow‐ to evaporation‐dominated stage of spin coating is disclosed; the vertical liquid–liquid phase separation incubates a supersaturated skin layer where fullerene aggregation and polymer crystallization occur and develop concomitantly. Shortly after the transition, the near‐surface structural development is largely pinned, leaving the solvent‐rich bottom layer to diminish via solvent diffusion and evaporation through the thickened skin layer that finally condenses into the spin‐coated film upon solvent depletion. The shear‐enhanced surface layering and supersaturation for the surface‐down nanostructural development are unexpected in all the existing structural models for PSCs. The mechanistic understanding of coupled vertical phase separation and local nanosegregation provides new insights and alternative strategy to the morphology control of spin‐cast PSC active layers in particular and various solution‐processed polymeric films in general.     

Highly Elastic Binder for Improved Cyclability of Nickel‐Rich Layered Cathode Materials in Lithium‐Ion Batteries

Nickel‐rich layered cathode materials are predominantly used for lithium‐ion batteries intended for electric vehicles owing to their high specific capacities and minimal use of high‐cost cobalt. The intrinsic drawbacks of nickel‐rich layered cathode materials with regard to cycle life and safety have largely been addressed by doping and by applying surface coatings. Here, it is reported that a highly elastic binder, namely spandex, can overcome the problems of nickel‐rich layered cathode materials and improve their electrochemical properties drastically. The high elasticity of spandex allows it to uniformly coat LiNi_0.8Co_0.1Mn_0.1O₂ particles via shear force during slurry mixing to protect the particles from undesired interfacial reactions during cycling. The uniform coating of spandex, together with its hydrogen bonding interaction with LiNi_0.8Co_0.1Mn_0.1O₂, leads to enhanced particle‐to‐particle interaction, which has multiple advantages, such as high loading capability, superior rate and cycling performance, and low binder content. This study highlights the promise of elastic binders to meet the ever‐challenging criteria with respect to nickel‐rich cathode materials in cells targeting electric vehicles.     

Thermodynamic Aspects of Cathode Coatings for Lithium‐Ion Batteries

Metal oxide cathode coatings are capable of scavenging the hydrofluoric acid (HF) (present in LiPF₆‐based electrolytes) and improving the electrochemical performance of Li‐ion batteries. Here, a first‐principles thermodynamic framework is introduced for designing cathode coatings that consists of four elements: i) HF‐scavenging enthalpies, ii) volumetric and iii) gravimetric HF‐scavenging capacities of the oxides, and iv) cyclable Li loss into coating components. 81 HF‐scavenging reactions involving binary s‐, p‐ and d‐block metal oxides and fluorides are enumerated and these materials are screened to find promising coatings based on attributes (i‐iv). The screen successfully produces known effective coating materials (e.g., Al₂O₃ and MgO), providing a validation of our framework. Using this design strategy, promising coating materials, such as trivalent oxides of d‐block transition metals Sc, Ti, V, Cr, Mn and Y, are predicted. Finally, a new protection mechanism that successful coating materials could provide by scavenging the wide bandgap and low Li ion conductivity LiF precipitates from the cathode surfaces is suggested.     

Growth of Collagen Fibril Seeds from Embryonic Tendon: Fractured Fibril Ends Nucleate New Tip Growth

Collagen fibrils are the principal tensile element of vertebrate tissues where they occur in the extracellular matrix as spatially organised arrays. A major challenge is to understand how the mechanisms of nucleation, growth and remodelling yield fibrils of tissue-specific diameter and length. Here we have developed a seeding system whereby collagen fibrils were isolated from avian embryonic tendon and added to purified collagen solution, in order to characterise fibril surface nucleation and growth mechanisms. Fragmentation of tendon in liquid nitrogen followed by Dounce homogenisation generated fibril length fragments. Most (> 94%) of the fractured ends of fibrils, which show an abrupt square profile, were found to act as nucleation sites for further growth by molecular accretion. The mechanism of this nucleation and growth process was investigated by transmission electron microscopy, atomic force microscopy and scanning transmission electron microscopy mass mapping. Typically, a single growth spur occurred on the N-terminal end of seed fibrils whilst twin spurs frequently formed on the C-terminal end before merging into a single tip projection. The surface nucleation and growth process generated a smoothly tapered tip that achieved maximum diameter when the axial extension reached ∼ 13 μm. Lateral growth also occurred along the entire length of all seed fibrils that contained tip projections. The data support a model of collagen fibril growth in which the broken ends of fibrils are nucleation sites for propagation in opposite axial directions. The observed fibril growth behaviour has direct relevance to tendon matrix remodelling and repair processes that might involve rupture of collagen fibrils.     

Influence of Polymer Seed Coatings, Soil Raking, and Time of Sowing on Seedling Performance in Post-Mining Restoration

This study represents part of a broader investigation into novel seed broadcasting methodologies as a means to optimize rehabilitation techniques following sand mining. Specifically, the study investigated the use of polymer seed coatings, time of sowing application, and in situ raking of the topsoil to optimize seedling recruitment to site. For polymer seed coatings, an ex situ trial was undertaken to evaluate seed coating effects on seedling emergence. Results demonstrated that seed coatings did not significantly inhibit maximum emergence percentage of 10 Banksia woodland species (out of 11 evaluated), but coated seeds from four species were on average 2–6 days slower to emerge than noncoated seeds. Seed coatings were found to have a greater effect in situ, with more coated seeds emerging than noncoated seeds. Topsoil raking (following seed sowing) and time of sowing were found to have the greatest impact on seedling emergence, with higher emergence following topsoil raking (5‐ to 90‐fold increase) and sowing in May (late autumn) (1.4‐ to 12‐fold increase) rather than in July (mid‐winter). The implications for mining rehabilitation are discussed, and areas for further research are considered.     

Immobilization of invertase in polyvinyl alcohol coatings

A possibility of invertase immobilization in the polyvinyl alcohol coating formed directly on the electrode surface from water solution of polyvinyl alcohol and boric acid was being investigated. Conditions for obtaining the polymeric coating at the constant potential and at the constant current were compared. In order to obtain the polymeric coatings with a marked enzyme activity optimal conditions were found.     

Development and Application of a Process Window for Achieving High-Quality Coating in a Fluidized Bed Coating Process

Next to the coating formulation, process conditions play important roles in determining coating quality. This study aims to develop an operational window that separates layering from agglomeration regimes and, furthermore, the one that leads to the best coating quality in a fluidized bed coater. The bed relative humidity and the droplet size of the coating aerosol were predicted using a set of engineering models. The coating quality was characterized using a quantitative image analysis method, which measures the coating thickness distribution, the total porosity, and the pore size in the coating. The layering regime can be achieved by performing the coating process at a certain excess of the viscous Stokes number (ΔSt _v). This excess is dependent on the given bed relative humidity and droplet size. The higher the bed relative humidity, the higher is the ΔSt _v required to keep the process in the layering regime. Further, it is shown that using bed relative humidity and droplet size alone is not enough to obtain constant coating quality. The changes in bed relative humidity and droplet size have been identified to correlate to the fractional area of particles sprayed per unit of time. This parameter can effectively serve as an additional parameter to be considered for a better control on the coating quality. High coating quality is shown to be achieved by performing the process close to saturation and spraying droplets small enough to obtain high spraying rate, but not too small to cause incomplete coverage of the core particles.     

Siloxane-based biocatalytic films and paints for use as reactive coatings

We have developed a new methodology for preparing films and paints suitable for use as biocatalytic coatings. The hydrolytic enzymes pronase and alpha-chymotrypsin were immobilized by either sol-gel entrapment or by covalent attachment into a polydimethylsiloxane (PDMS) matrix and cast into thin films or incorporated into an oil-based paint formulation. All of the coatings retained enzymatic activity and adhered to several different materials. The enzymatic films and paints also exhibited higher thermostability than enzyme free in solution or covalently attached to the outer surface of PDMS. A porous membrane based on a PDMS-immobilized enzyme was also prepared by an immersion precipitation process. Protein adsorption measurements showed that the enzyme-containing films and paints adsorbed less protein than enzyme-free controls, and that protein adsorption decreased with increasing proteolytic activity of the coating. These coatings thus provide the means to apply a stable enzymatic surface to a wide range of materials, and may be generally useful as biocatalytic paints and films.     

Trypsin crystallization by membrane-based techniques

To grow protein crystals is not an easy task; moreover, if we need to grow protein crystals with controlled shape, size, and size distribution, depending on their application, the mission becomes even harder. Membrane crystallization has been recognized as an interesting tool for growing protein crystals with enhanced crystallization kinetics, both in static and in forced solution flow configuration, without detrimental effects on crystal quality. In the present work, we have studied the membrane crystallization process of benzamidine inhibited trypsin from bovine pancreas (BPT), with ammonium sulphate (dissolved in Tris-HCl buffer, 0.1 M, pH 8.5), as precipitant agent. We have demonstrated that, by using the membrane crystallization technique, BPT crystals can be obtained in 24-48 h, in static configuration, and in 4-7 days, in a forced solution flow system, depending on the experimental conditions. Furthermore, the kinetics of BPT crystallization have been modulated, to control the morphological characteristics of the crystals produced, by an accurate selection of the operative parameters involved in the process. The active membrane surface and the flow rate of extraction solvent in quiescent configuration, and the solution velocity in forced convection solution experiments, were the parameters investigated. In this respect, membrane crystallization techniques have been assessed as an interesting way for growing proteins, and more specifically enzyme crystals, with high control on the final properties of the crystalline material produced, with potential fundamental implication in the field of structural biology and biotechnology.     

Beta irradiation may induce stereoselectivity in the crystallization of optical isomers

A novel approach has been introduced to detect the manifestation of symmetry breaking weak interactions at molecular level. In the racemic conglomerate crystallization of D, L-sodium-ammonium tartrate the effect of³²P irradiation was studied by measuring the weight and optical purity of the crystalline phase as well as the size distribution of the crystallites. The high number of independent experiments (over 1000) permitted statistical analysis of the results. The following observations have been made:

1. Beta irradiation influences the crystallization process, irradiated samples yield more crystalline material.
2. The effect involves presumably crystal seed formation because from the irradiated solutions more and smaller crystallites are formed.
3. The presence of beta particles induces stereoselective crystallization, the crystalline phase shows optical activity characteristic of the “unnatural” L-isomer.
4. The above changes are attributed to the beta irradiation as the magnitude of the effects depends on the amount of added radioactivity. Optically active contaminants are highly unlikely sources of the differences between irradiated and control series.
5. In the absence of³²P the tartrate enantiomers have equal probability to form crystals, i.e., the contribution of mixing of weak interaction into the electromagnetic one is not measurable in this system.

     

Polymer Solar Cells with Efficiency >10% Enabled via a Facile Solution‐Processed Al‐Doped ZnO Electron Transporting Layer

A facile and low‐temperature (125 °C) solution‐processed Al‐doped ZnO (AZO) buffer layer functioning very effectively as electron accepting/hole blocking layer for a wide range of polymer:fullerene bulk heterojunction systems, yielding power conversion efficiency in excess of 10% (8%) on glass (plastic) substrates is described. The ammonia‐treatment of the aqueous AZO nanoparticle solution produces compact, crystalline, and smooth thin films, which retain the aluminum doping, and eliminates/reduces the native defects by nitrogen incorporation, making them good electron transporters and energetically matched with the fullerene acceptor. It is demonstrated that highly efficient solar cells can be achieved without the need for additional surface chemical modifications of the buffer layer, which is a common requirement for many metal oxide buffer layers to yield efficient solar cells. Also highly efficient solar cells are achieved with thick AZO films (>50 nm), highlighting the suitability of this material for roll‐to‐roll coating. Preliminary results on the applicability of AZO as electron injection layer in F8BT‐based polymer light emitting diode are also presented.     

Aerosol‐Jet‐Assisted Thin‐Film Growth of CH3NH3PbI3 Perovskites—A Means to Achieve High Quality,Defect‐Free Films for Efficient Solar Cells

A high level of automation is desirable to facilitate the lab‐to‐fab process transfer of the emerging perovskite‐based solar technology. Here, an automated aerosol‐jet printing technique is introduced for precisely controlling the thin‐film perovskite growth in a planar heterojunction p–i–n solar cell device structure. The roles of some of the user defined parameters from a computer‐aided design file are studied for the reproducible fabrication of pure CH₃NH₃PbI₃ thin films under near ambient conditions. Preliminary power conversion efficiencies up to 15.4% are achieved when such films are incorporated in a poly(3,4‐ethylenedioxythiophene):polystyrene sulfonate‐perovskite‐phenyl‐C71‐butyric acid methyl ester type device format. It is further shown that the deposition of atomized materials in the form of a gaseous mist helps to form a highly uniform and PbI₂ residue‐free CH₃NH₃PbI₃ film and offers advantages over the conventional two‐step solution approach by avoiding the detrimental solid–liquid interface induced perovskite crystallization. Ultimately, by integrating full 3D motion control, the fabrication of perovskite layers directly on a 3D curved surface becomes possible. This work suggests that 3D automation with aerosol‐jet printing, once fully optimized, could form a universal platform for the lab‐to‐fab process transfer of solution‐based perovskite photovoltaics and steer development of new design strategies for numerous embedded structural power applications.     

Effect of tetracycline base crystallization on the conditions properties of the powders and drug forms obtained. The development of directed crystallization procedures for tetracycline base]

The study of the process of tetracycline base crystallization showed that with an increase in the rate of pH, temperature and mixed rotation changes, the specific surface of the crystalline precipitate increased with a simultaneous decrease in the bulk weight, looseness and volume density of the powder. The residual content of tetracycline in the mother solution decreased. The level of the effect of various parameters on the final results was different.     

Adhesion,Vitality and Osteogenic Differentiation Capacity of Adipose Derived Stem Cells Seeded on Nitinol Nanoparticle Coatings

Autologous cells can be used for a bioactivation of osteoimplants to enhance osseointegration. In this regard, adipose derived stem cells (ASCs) offer interesting perspectives in implantology because they are fast and easy to isolate. However, not all materials licensed for bone implants are equally suited for cell adhesion. Surface modifications are under investigation to promote cytocompatibility and cell growth. The presented study focused on influences of a Nitinol-nanoparticle coating on ASCs. Possible toxic effects as well as influences on the osteogenic differentiation potential of ASCs were evaluated by viability assays, scanning electron microscopy, immunofluorescence and alizarin red staining. It was previously shown that Nitinol-nanoparticles exert no cell toxic effects to ASCs either in soluble form or as surface coating. Here we could demonstrate that a Nitinol-nanoparticle surface coating enhances cell adherence and growth on Nitinol-surfaces. No negative influence on the osteogenic differentiation was observed. Nitinol-nanoparticle coatings offer new possibilities in implantology research regarding bioactivation by autologous ASCs, respectively enhancement of surface attraction to cells.     

Effect of W–TiO2 composite to control microbiologically influenced corrosion on galvanized steel

Microorganisms tend to colonize on solid metal/alloy surface in natural environment leading to loss of utility. Microbiologically influenced corrosion or biocorrosion usually increases the corrosion rate of steel articles due to the presence of bacteria that accelerates the anodic and/or cathodic corrosion reaction rate without any significant change in the corrosion mechanism. An attempt was made in the present study to protect hot-dip galvanized steel from such attack of biocorrosion by means of chemically modifying the zinc coating. W–TiO₂ composite was synthesized and incorporated into the zinc bath during the hot-dipping process. The surface morphology and elemental composition of the hot-dip galvanized coupons were analyzed by scanning electron microscopy and energy dispersive X-ray spectroscopy. The antifouling characteristics of the coatings were analyzed in three different solutions including distilled water, seawater, and seawater containing biofilm scrapings under immersed conditions. Apart from electrochemical studies, the biocidal effect of the composite was evaluated by analyzing the extent of bacterial growth due to the presence and absence of the composite based on the analysis of total extracellular polymeric substance and total biomass using microtiter plate assay. The biofilm-forming bacteria formed on the surface of the coatings was cultured on Zobell Marine Agar plates and studied. The composite was found to be effective in controlling the growth of bacteria and formation of biofilm thereafter.     

Following the Morphology Formation In Situ in Printed Active Layers for Organic Solar Cells

The device performance of organic polymer:fullerene bulk heterojunction solar cells strongly depends on the interpenetrating network of the involved donor and acceptor materials in the active layer. Since morphology formation depends on the conditions of film preparation, the final morphology varies for different deposition methods. In order to understand and optimize industrial coating processes and, therefore, the performance of the solar cells produced, a deeper understanding of structure formation is important. In situ measurements of slot‐die printed polymer:fullerene active layers are presented that reveal insights into the evolution of the structure. Polymer crystallization and ordering is monitored by in situ grazing incidence wide angle X‐ray scattering (GIWAXS), and in situ grazing incidence small‐angle X‐ray scattering (GISAXS). The development of the morphology exhibits five stages independent of the drying conditions. Two growth rates are observed, an initial slow formation of poly(3‐hexylthiophene‐2,5‐diyl) crystallites in well‐aligned edge‐on orientation followed by a rapid crystal growth. By combining the GIWAXS and GISAXS measurements, a five‐stage growth and assembly process is found and described in detail along with a proposed model of the structural evolution. The findings are an important step in tailoring the assembly process.