Project, Design, and Use of a Pilot Plant for Nanocapsule Production

The aim of this study was to find the scale-up parameters necessary for the preparation of nanocapsules (NCs) for pharmaceutical purposes. Starting from the laboratory scale (0.06 L), we designed and assembled a pilot plant (2 L) to produce NCs with the so-called emulsification-diffusion technique. We wanted to check if classical tools adequate for the pharmaceutical industry and for industrial scale-up purposes according to well-known chemical engineering technique could be used to perform the NC preparation. Experiments were carried out by varying some operative parameters, such as the impeller speed, the agitation duration for the emulsion preparation, and the reagent concentrations. As expected, good accordance between the NC produced at the laboratory scale and at the pilot plant scale was obtained. We conclude that the pilot plant can be used to perform a scale-up study of the industrial production of NC.     

Removal of lead (II) ions from synthetic and real effluents using immobilized Pinus sylvestris sawdust: adsorption on a fixed-bed column

The purpose of this work was to evaluate the potential of Pinus sylvestris sawdust, in a continuous flow removal of lead (II) ions from synthetic and industrial aqueous effluents. The kinetic parameters obtained in a batch process were used to scale-up the process on a mini-column and to choose the breakthrough model. The column experimental data concerning the volumes treated were correlated using the bed depth service time model. These experimental data closely fitted the bed depth service time model at 10% of the breakthrough curve. The results from the bed depth service time model on the mini-column were then used to design a pilot plant adsorption unit. The performance of the pilot plant column accurately agreed with that obtained from the mini-column. The experiments carried out in a dynamic reactor allowed to bring out the influence of various parameters on the efficiency of the P. sylvestris sawdust. In addition, the process was checked for the treatment of industrial aqueous effluents on a pilot plant scale and the results were in accordance with those obtained from synthetic effluents.     

Destillation im Fein- und Hochvakuum

The distillation in the fine and high vacuum range requires not only appropriate vacuum pumps but also special apparatus and machines. The principle and the design of laboratory and industrial plants are explained. New mathematical methods are supporting laboratory and pilot testing required for process development and plant layout. An example was chosen for demonstration purposes.     

Preparation and stability of iodine/α-cyclodextrin inclusion complex

Abstract

Inclusion complexes of iodine and α-cyclodextrin were prepared using the coprecipitation method. The complexes obtained were characterized in their solid state using differential scanning calorimetry and in their liquid phase using spectrophotometry, titrimetry and electrochemistry assays. The inclusion and preparation yields were determined. The 1:1 stoichiometry ratio of the inclusion compound was estimated on the basis of the inclusion yield. After optimization of the parameters of the laboratory assays, a scale-up experiment for the complex preparation was carried out. Stability studies showed that, after 16 months preservation, the inclusion complex remained quite stable and suitable for industrial scale-up according to a number of conditions.     

Robust, functional nanocrystal solids by infilling with atomic layer deposition

Thin films of colloidal semiconductor nanocrystals (NCs) are inherently metatstable materials prone to oxidative and photothermal degradation driven by their large surface-to-volume ratios and high surface energies. (1) The fabrication of practical electronic devices based on NC solids hinges on preventing oxidation, surface diffusion, ripening, sintering, and other unwanted physicochemical changes that can plague these materials. Here we use low-temperature atomic layer deposition (ALD) to infill conductive PbSe NC solids with metal oxides to produce inorganic nanocomposites in which the NCs are locked in place and protected against oxidative and photothermal damage. Infilling NC field-effect transistors and solar cells with amorphous alumina yields devices that operate with enhanced and stable performance for at least months in air. Furthermore, ALD infilling with ZnO lowers the height of the inter-NC tunnel barrier for electron transport, yielding PbSe NC films with electron mobilities of 1 cm2 V(-1) s(-1). Our ALD technique is a versatile means to fabricate robust NC solids for optoelectronic devices.     

Improved photovoltaic performances by post-deposition acidic treatments on tetrapod shaped colloidal nanocrystal solids

The ligand exchange reaction with pyridine is the standard procedure for the integration of colloidal semiconductor nanocrystals (NCs) in photovoltaic devices; however, for large sized and irregularly shaped branched NCs, such as CdSe@CdTe tetrapods, this procedure can lead to a considerable waste of materials and the aggregation of NCs in the colloidal solution, therefore resulting in the formation of an inhomogeneous film and low device performances. Here, we report on alternative post-deposition treatments with carboxylic acids on films of CdSe@CdTe tetrapod shaped NCs. This approach guarantees the removal of the insulating surfactant, necessary to obtain good charge transport among NCs, while preserving the film integrity. We perform a complete characterization of the nanocrystalline films treated with different carboxylic acids and demonstrate the successful integration of such films in photovoltaic devices, showing a doubled efficiency with respect to the standard ligand exchange procedure. Our approach represents a general route towards the development of NC based devices with improved performances and minimized waste of material.     

Nonvolatile Memory Characteristics of NMOSFET With Ag Nanocrystals Synthesized via a Thermal Decomposition Process for Uniform Device Distribution

This paper presents nonvolatile memory characteristics using Ag nanocrystals (NCs) formed by a thermal decomposition and size-selective precipitation technique for Flash memory application. In the NC formation process, the size of NCs and the space NC-to-NC were precisely controlled by a size-selective precipitation technique and the length of the self-assembled monolayer surrounding the NCs, respectively. The size and density of the Ag NCs synthesized were typically 3-5 nm and , respectively. Due to the regularly distributed Ag NCs with high density, uniform memory characteristics and high program efficiency were achieved from NMOSFETs embedded with the Ag NCs, which were fabricated by the gate-last process.     

Power of experimental design studies for the validation of pharmaceutical processes: case study of a multilayer tablet manufacturing process

Experimental design studies (EDS) are already widely used in the pharmaceutical industry for drug formulation or process optimization. Rare are the situations in which this methodology is applied for validation purposes. The power of this statistical tool, key element of a global validation strategy, is demonstrated for a multilayer tablet manufacturing process. Applied to the Geomatrix® system generally composed of one compression and three granulation processes, time and strictness gains are non-negligible. Experimental design studies are not used in this work for modeling. Introduced at each important step of the process development, they allow for the evaluation of process ruggedness at pilot scale and specifications for full production. A demonstration of the complete control of key process parameters is given, identified throughout preliminary studies.     

Particle size separation via soil washing to obtain volume reduction.

A pilot-plant study was performed using a soil washing pilot plant originally designed by the Environmental Protection Agency (EPA) to demonstrate scale-up and potential full-scale remediation. This pilot plant named VORCE (Volume Reduction/Chemical Extraction) was modified to meet the specific requirements for treatment of the Formerly Utilized Sites Remedial Action Program (FUSRAP) and a Department of Energy site soils. After a series of tests on clean soils to develop operating parameters and system performance, the machine was used to treat soils, one contaminated with Thorium-232 and the other with Cesium-137. All indicate that soil washing is very promising for volume reduction treatment. In addition, cost data was generated and is given herein.     

Capillary electrophoresis, mass spectrometry, and UV-visible absorption studies on electrolyte-induced fractionation of gold nanoclusters

We describe a novel and simple electrolyte-induced fractionation method to separate a polydisperse water-soluble gold nanocluster (Au NC) product. Different particle sizes of Au NC fractions can be easily centrifuged down as a function of the electrolyte concentration or lipophilicity of the solution. The changes in the absorption characteristic of the Au NC fractions under different electrolyte/ethanol conditions demonstrate the change in particle size distribution of the Au NC. Small gold nanoclusters, Au10, Au11, Au12, and Au15, were separated from the Au10-Au50 polydisperse Au NC product under various phosphate/ethanol conditions. The core size separation of Au NC was evaluated by their migration trends in capillary zone electrophoresis, UV-visible absorption, and mass spectra. The electrolyte-induced fractionation not only provides a convenient method to separate small Au NC mixture but also assists in the study of the photophysical properties of smaller Au NCs that are present with the larger Au NCs in a polydisperse Au NC product.     

Breakdown of volume scaling in Auger recombination in CdSe/CdS heteronanocrystals: the role of the core-shell interface

Spatial confinement of electronic excitations in semiconductor nanocrystals (NCs) results in a significant enhancement of nonradiative Auger recombination (AR), such that AR processes can easily dominate the decay of multiexcitons. AR is especially detrimental to lasing applications of NCs, as optical gain in these structures explicitly relies on emission from multiexciton states. In standard NCs, AR rates scale linearly with inverse NC volume. Here, we investigate multiexciton dynamics in hetero-NCs composed of CdSe cores and CdS shells of tunable thickness. We observe a dramatic decrease in the AR rates at the initial stage of shell growth, which cannot be explained by traditional volume scaling alone. Rather, fluorescence-line-narrowing studies indicate that the suppression of AR correlates with the formation of an alloy layer at the core-shell interface suggesting that this effect derives primarily from the "smoothing" of the confinement potential associated with interfacial alloying. These data highlight the importance of NC interfacial structure in the AR process and provide general guidelines for the development of new nanostructures with suppressed AR for future lasing applications.     

A new route to size and population control of silver clusters on colloidal TiO₂ nanocrystals

Formation of hybrid Ag-TiO(2) nanocrystals (NCs) in which Ag clusters are uniformly deposited on individual TiO(2) NC surface has been achieved by using hydrophobic surfactant-capped TiO(2) NCs in combination with a photodeposition technique. The population of Ag clusters on the individual TiO(2) NC surface can be controlled by the degree of hydrophobicity (e.g., the number of vacant sites) on the TiO(2) NC surface while their size may be altered simply by varying irradiation time. A reversible change in color of the resulting hybrid Ag-TiO(2) NCs is induced by alternating UV light and visible-light illumination; however, the size and population of Ag clusters on TiO(2) NCs are almost unchanged. Furthermore, these materials also exhibit much higher photocatalytic performance as compared to that of Ag supported on commercial TiO(2)-P25.     

Power of Experimental Design Studies for the Validation of Pharmaceutical Processes: Case Study of a Multilayer Tablet Manufacturing Process

ABSTRACT

Experimental design studies (EDS) are already widely used in the pharmaceutical industry for drug formulation or process optimization. Rare are the situations in which this methodology is applied for validation purposes. The power of this statistical tool, key element of a global validation strategy, is demonstrated for a multilayer tablet manufacturing process. Applied to the Geomatrix® system generally composed of one compression and three granulation processes, time and strictness gains are non-negligible. Experimental design studies are not used in this work for modeling. Introduced at each important step of the process development, they allow for the evaluation of process ruggedness at pilot scale and specifications for full production. A demonstration of the complete control of key process parameters is given, identified throughout preliminary studies.     

C2 用于声化学研究的大功率超声系统的研制

根据声化学反应的特殊要求，我们研制了上前用于声化学研究的大功率超声系统，由参数可调节的超声发生器配合不同频率的换能器工作，并用它组合成杯式幅杆结构声化学反应器，解决了有关声化学设备的一些技术问题。为声化学技术从实验室规模向工业应用过渡做了必要的准备。     

Hybrid nanocomposites based on luminescent colloidal nanocrystals in poly(methyl methacrylate): spectroscopical and morphological studies

We report on preparation process and optical characterization of a nanocomposite material obtained dispersing colloidal semiconductor nanocrystals (NCs), namely CdS and CdSe@ZnS core-shell system in poly(methyl methacrylate) (PMMA). Such method allows a large flexibility on nanocrystal materials and on the choice of the polymer characteristics. Nanocomposite thin films were extensively investigated by means optical and morphological techniques. The effects on NC composition, concentration, size, and surface chemistry on the spectroscopical and structural behaviour of the nanocomposite properties were studied. The NC size dependent optical properties of the nanocomposites are mainly accounted by the NC composition and size, while the morphology of the films is explained on the base of the NC surface characteristics and their concentration in the nanocomposites.     

A NONLINEAR POPULATION BALANCE APPROACH TO WET BALL MILL SCALE-UP DESIGN

Recent research has shown that population balance models hold considerable promise as a basis for accurate ball mill scale-up from laboratory batch grinding tests. Researchers at the University of Utah have developed and tested a scale-up approach based on linear population balance models which when used with an “experimental linearization” procedure (referred to as a similar fineness testing) produces accurate predictions of mill dimensions and product size distributions for commerical mills.

Since wet ball mill grinding kinetics are often highly nonlinear and the similar fineness procedure required to apply the linear model can be somewhat tedious experimentally, the development of a scale-up approach based on a nonlinear model which is experimentally simpler to use is desirable. In the current paper an approach involving an empirical nonlinear kinetic model and a distributed volume model for material transport is evolved. The approach Is tested by predicting mill performance for a variety of materials (limestone, quartz, iron ore concentrate) in pilot and commercial scale mills (up to 14ft. in diameter) based on data obtained in a 10 inch diameter batch ball mill.     

C2用于声化学研究的大功率超声系统的研制

根据声化学反应的特殊要求，我们研制了用于声化学研究的大功率超声系统，由参数可调节的超声发生器配合不同频率的换能器工作，并用它组合成杯式变幅杆结构声化学反应器。解决了有关声化学设备的一些技术问题，为声化学技术从实验室规模向工业应用过渡做了必要的准备     

High-shear granulation of high-molecular weight hypromellose: effects of scale-up and process parameters on flow and compaction properties

Context: Knowledge of the effects of high-shear granulation process parameters and scale-up on the properties of the produced granules is essential for formulators who face challenges regarding poor flow and compaction during development of modified release tablets based on high-molecular weight hypromellose (hydroxypropylmethylcellulose (HPMC)) polymers. Almost none of the existing studies deal with realistic industrial formulation.

Objective: The aim was to investigate the effects of scale-up and critical process parameters (CPPs) of high-shear granulation on the quality attributes of the granules, particularly in terms of the flow and compaction, using a realistic industrial formulation based on HPMC K100M polymer.

Methods: The flow properties were determined using flow time, Carr index, tablet mass, and crushing strength variations. The compaction properties were quantified using the ‘out-of-die’ Heckel and modified Walker models, as well as the tensile strength profile and elastic recovery. High-shear granulation was performed at different scales: 4?L, 300?L, and 600?L.

Results and conclusion: The scale itself had larger effects on the granule properties than the CPPs, which demonstrated high robustness of formulation on the individual scale level. Nevertheless, to achieve the desired flow and compaction, the values of the CPPs need to be precisely selected to fine-tune the process conditions. The best flow was achieved at high volumes of water addition, where larger and more spherical granules were obtained. The CPPs showed negligible influence on the compaction with no practical implications, however, the volume of water addition volume was identified as having the largest effects on compaction.     

Shape-controlled synthesis of metal nanocrystals–multiwalled carbon nanotubes hybrid structures via electrodeposition

We have exploited a method for the synthesis of metal nanocrystals (NCs) with distinct geometries on multiwalled carbon nanotubes (MWCNTs) by employing the electrodeposition technique at room-temperature. The method has been demonstrated for the Cu NCs–MWCNTs hybrid structures. The shape of the Cu NCs on MWCNTs has been effectively manipulated by simply tuning the applied potential. The present work provides an alternative approach for the large scale synthesis of shape-controlled metal or/and alloy NCs–MWCNTs hybrid structures for a wide range of applications.     

Air stable, photosensitive, phase pure iron pyrite nanocrystal thin films for photovoltaic application

Iron pyrite (FeS(2)) is a naturally abundant and nontoxic photovoltaic material that can potentially make devices as efficient as silicon-based ones; however existing iron pyrite photovoltaic devices contain thermodynamically unstable FeS(2) film surfaces that lead to low open circuit voltages. We report the rational synthesis of phase pure, highly crystalline cubic FeS(2) nanocrystals (NCs) using a trioctylphosphine oxide (TOPO) assisted hot-injection method. The synthesized pyrite NC films have excellent air stability over one year. In contrast, obvious surface decomposition was observed on the surface of FeS(2) NCs synthesized without TOPO. A high carrier mobility of 80 cm(2)/(V s) and a strong photoconductivity were observed for the first time for pyrite films at room temperature. Our results indicate that TOPO passivates both iron and sulfur atoms on FeS(2) NC surfaces, efficiently inhibiting surface decomposition.