Two-chamber Setup Research Articles

Investigations on the dustiness of binary acetaminophen - lactose monohydrate powder blends

In this study, binary powder blends of acetaminophen (ACAM) and α-lactose monohydrate (LM) at different mixing ratios, with fine, medium-size, and coarse particles are investigated with a new two-chamber setup (TCS) to assess dustiness. The TCS consists of an emission and a detection chamber, allowing plain diffusive or convective particle transport. The aim is to compare the diffusive transport of ACAM with binary blends of ACAM and LM at different particle sizes and similar apparent density. Fine ACAM exhibits significantly higher dust emissions compared to medium and coarse ACAM. With increasing LM portion in the blends, ACAM dust emissions decrease. The blend of fine ACAM and coarse LM shows the highest dust emission, while the blend of coarse ACAM and fine LM reveals the lowest emissions. The TCS offers precise, reproducible measurements with good repeatability, making it beneficial for laboratory and industrial applications, even with small powder quantities.

An Investigation on the Relationship between Dust Emission and Air Flow as Well as Particle Size with a Novel Containment Two-Chamber Setup.

In the present study with a novel two-chamber setup (TCS) for dustiness investigations, the relationship between pressure differences as well as air velocities and the resulting dust emissions is investigated. The dust emissions of six particle size fractions of acetaminophen at pressure differences between 0 and 12 Pa are examined. The results show that both simulated and measured air velocities increase with increasing pressure difference. Dust emissions decrease significantly with increasing pressure difference and air velocity. Fine particles cause higher dust emissions than coarse particles. A high goodness of fit is obtained with exponential and quadratic functions to describe the relationship between pressure difference and dust emission, indicating that even moderate increases in pressure may lead to a reduction in the emission. Average air velocities within the TCS simulated with Computational Fluid Dynamics are between 0.09 and 0.37 m/s, whereas those measured experimentally are between 0.09 and 0.41 m/s, both ranges corresponding to the recommended values for effective particle separation in containment systems. These results underline the ability of the novel TCS to control pressure and airflow, which is essential for reliable dust emission measurements and thus provide support for further scientific and industrial applications.

Oxygen Permeation Measurement of LaCrO3-based Interconnect Embedded in Real SOFCs

A method for evaluating the oxygen permeation flux through LaCrO3-based interconnects embedded in real solid oxide fuel cells (SOFCs) is proposed. The interconnect of the cell was placed in a two-chamber setup (fuel | interconnect | air), and the oxygen permeation flux was successfully determined by quantifying the amount of water vapor generated at the fuel side due to the permeation of oxygen from the air side to the fuel side. Using the proposed method, the oxygen permeation fluxes through the interconnects of the cells before and after 20,000 h of continuous operation were compared to examine the long-term stability of the LaCrO3-based interconnects. No significant difference was observed in the oxygen permeation flux before and after continuous operation, indicating that the LaCrO3-based interconnects have excellent chemical and thermal stability. In addition, the effect of oxygen permeation on energy conversion efficiency was investigated by calculating the Nernst loss. The calculations showed that oxygen permeation has almost no effect on the energy conversion efficiency.

Prediction of Bleeding via Simulation of Hydrodynamics in Centrifugal Partition Chromatography

Centrifugal Partition Chromatography (CPC) utilizes a two-phase liquid–liquid system as mobile and stationary phases. During operation, the latter continuously drains out of the rotor, despite it being in fact stationary, leading to decreasing separation efficiency over time, a phenomenon still poorly understood today because neither simulations nor extensive experimental investigations have addressed this so-called bleeding. With the model presented in this study, the underlying hydrodynamics are discussed in detail. This model can simulate bleeding over 60 s and is verified experimentally for different operating points (volumetric flow rates of 5, 12, and 20 mL⋅min−1) of the Centrifugal Partition Chromatograph utilizing an aqueous–organic phase system. We simulated two interconnected chambers at the rotor inlet and analyzed the loss of the stationary phase over time. The results of the simulated second chamber are closely aligned with the experimental validation results. Thus, the prediction of bleeding utilizing the simulation of hydrodynamics was successful. Moreover, we highlighted the benefits of the two-chamber setup modeled in this study compared to single-chamber models.

Coulomb interactions for mediator-enhanced sensitized triplet-triplet annihilation upconversion in solution.

Sensitized triplet-triplet annihilation upconversion offers an attractive possibility to replace a high-energy photon by two photons with lower energy through the combination of a light-harvesting triplet sensitizer and an annihilator for the formation of a fluorescent singlet state. Typically, high annihilator concentrations are required to achieve an efficient initial energy transfer and as a direct consequence the most highly energetic emission is often not detectable due to intrinsic reabsorption by the annihilator itself. Herein, we demonstrate that the addition of a charge-adapted mediator drastically improves the energy transfer efficiency at low annihilator concentrations via an energy transfer cascade. Inspired by molecular dyads and recent developments in nanocrystal-sensitized upconversion, our system exploits a concept to minimize intrinsic filter effects, while boosting the upconversion quantum yield in solution. A sensitizer-annihilator combination consisting of a ruthenium-based complex and 9,10-diphenylanthracene (DPA) is explored as model system and a sulfonated pyrene serves as mediator. The impact of opposite charges between sensitizer and mediator - to induce coulombic attraction and subsequently result in accelerated energy transfer rate constants - is analyzed in detail by different spectroscopic methods. Ion pairing and the resulting static energy transfer in both directions is a minor process, resulting in an improved overall performance. Finally, the more intense upconverted emission in the presence of the mediator is used to drive two catalytic photoreactions in a two-chamber setup, illustrating the advantages of our approach, in particular for photoreactions requiring oxygen that would interfere with the upconversion system.

Carbonylative Transformations Using a DMAP-Based Pd-Catalyst through Ex Situ CO Generation.

A phosphine-free, efficient protocol for aminocarbonylation and carbonylative Suzuki-Miyaura coupling has been developed using a novel palladium complex, [PdII(DMAP)2(OAc)2]. The complex was successfully synthesized using a stoichiometric reaction between PdII(OAc)2 and DMAP in acetone at room temperature and characterized using single-crystal X-ray analysis. Only 5 mol % catalyst loading was sufficient for effective carbonylative transformations. "Chloroform-COware" chemistry was utilized for safe and facile insertion of the carbonyl unit using chloroform as an inexpensive CO source in a two-chamber setup. Various value-added pharmaceutically relevant compounds such as CX-516, CX-546, and farampator were synthesized using the technique. Furthermore, the commercially designed COware was engineered to COware-RB setup for sequential one-pot synthesis of indenoisoquinolines (topoisomerase I inhibitors).

A Novel Two-Chamber Setup for Containment Investigations with Special Focus on the Dustiness of Pharmaceutical Powders Depending on the Airflow.

In the present study, it was shown that a newly developed two-chamber setup (TCS) for containment investigations consisting of an emission and a detection chamber may serve to predict the dustiness of HPAPIs in a sealed system at different flow conditions. These flow conditions include the plain diffusive transport and the diffusive transport with the oppositely directed convective flow of airborne particles of the safe surrogate substance acetaminophen (ACAM). A linear correlation was found between an atomized amount of up to 400 mg of ACAM and the resulting dust emissions. The dust emission was reduced significantly by an oppositely directed convective flow. The results from the examinations, using either atomized ACAM or smoke for the determination of the evacuation time of the detection chamber, indicated that both methods are comparable. Furthermore, computational fluid dynamics (CFD) simulations were performed to determine the evacuation time. A time period of 9 min was sufficient for a reproducible evacuation and a reliable detection of most airborne ACAM particles within the detection chamber. CFD simulations were also carried out to simulate the air velocity resulting from various pressure differences and to visualize the flow of the airborne particles within the detection chamber.

Nicotinamide adenine dinucleotide hydrogen regeneration in a microbial electrosynthesis system by Enterobacter aerogenes

Costly cofactors such as nicotinamide adenine dinucleotide hydrogen (NADH) are essential to have high activity in many redox enzymatic processes. Cofactor regeneration methods have been suggested to improve the economic aspects of the system. Here, we introduce a microbial electrosynthesis process to regenerate NADH in a two-chamber set-up with Enterobacter aerogenes biofilm as the bio-cathode. The effects of several important factors on the regeneration efficiency were studied and the highest NADH regeneration yield was achieved equal to 65 % at the potential of −1.5 V and the initial NAD+ concentration of 1 mM after 8 h of operation. The regenerated cofactor was highly enzymatically active (93 ± 4 %) which was a great merit of the process. Studying the kinetics of regeneration revealed that the electron transfer rate to the biofilm was the limiting factor. We tried to remove the limitation through co-culturing Pseudomonas aeruginosa and producing more electrochemical active compounds in the biofilm. Although, this modification was not effective for the regeneration yield, it showed that the external potential implicitly influenced the regeneration process by changing the internal microbial cell metabolic fluxes. Finally, it can be concluded that the microbial electrosynthesis is a promising green process for NADH regeneration.

Biotin-NeutrAvidin Mediated Immobilization of Polymer Micro- and Nanoparticles on T Lymphocytes.

Cells are powerful carriers that can help to improve the delivery of nanomedicines. One approach to use cells as carriers is to immobilize the nanoparticulate cargo on the cell surface. While a plethora of chemical conjugation strategies are available to bind nanoparticles to cell surfaces, only relatively little is known about the effects of particle size and cell type on the surface immobilization of nanoparticles. This study investigates the biotin-NeutrAvidin mediated immobilization of model polymer nanoparticles with sizes ranging from 40 nm to 1 μm on two different T cell lines, viz., human Jurkat cells as well as mouse SJL/PLP7 T cells, which are of potential interest for drug delivery across the blood-brain barrier. The nanoparticle cell surface immobilization and the particle surface concentration and distribution were analyzed by flow cytometry and confocal microscopy. The functional properties of nanoparticle-modified SJL/PLP7 T cells were assessed in an ICAM-1 binding assay as well as in a two-chamber setup in which the migration of the particle-modified T cells across an in vitro model of the blood-brain barrier was studied. The results of these experiments highlight the effects of particle size and cell line on the surface immobilization of nanoparticles on living cells.

A Convenient Multigram Synthesis of DABSO Using Sodium Sulfite as SO2 Source

A convenient synthesis of DABCO·(SO2)2 (abbreviated as DABSO) is reported. Using a two-chamber setup, sulfur dioxide is generated in one chamber and consumed in the other. This closed system overcomes safety issues related to working with toxic SO2 gas. Pressure build-up is avoided by gradually generating the gas using sodium sulfite as precursor. Moreover, only near-stoichiometric amounts of SO2 are required for this protocol. The use of anhydrous solvents is not necessary, and every step is performed at room temperature. A scale-up was carried out on a 10 g scale which, after overnight drying, resulted in a quantitative yield.

Comparison of Coronal Leakage in Tooth Preparation with Two Single File Systems and Three Obturation Techniques.

Aims and Objectives:Root canal preparation and obturation are of great importance in endodontics. Its purpose is to eliminate pulpal and periradicular disease. The aim of this study was to compare coronal bacterial microleakage in prepared root canals using Neoniti A1 and Reciproc files that obturated with lateral compaction, single cone gutta-percha, and hybrid (tapered cone/lateral compaction) methods.Materials and Methods:In this ex vivo study, a total of 110 single-rooted mandibular first premolars were choose and randomly divided into two study groups A and B (each 45) that one group was prepared with Reciproc and another with Neoniti A1 and negative and positive control groups (each 10). Each group divided into three subgroups of 15 each and obturated using a single cone, lateral compaction, and hybrid (tapered cone/lateral compaction) techniques. For evaluation of coronal leakage, “two-chamber setup” was used. The solution of enterococcus faecalis culture was injected in the upper chamber and incubated. If the bacteria pass through the canal and obturation materials, the lower chamber becomes turbid. TSB medium in the lower chamber (apex) were investigated every day in terms of occurrence of turbidity, and the duration of occurrence of leakage was recorded. The data were analyzed using Chi-square test.Results:Data analysis showed that in each group the difference in percentages between subgroups was statistically significant (P = 0.003). So that the highest and the lowest amount of leakage in both groups were related to lateral compaction and hybrid techniques, respectively.Conclusion:Under the conditions of this study, independent of the instrument used for canal preparation, hybrid method and then single-cone technique, however, were more effective in the prevention of coronal leakage than lateral condensation technique.

Lithium migration in a two-chamber set-up as treatment against expansion due to alkali–silica reaction

Alkali–silica reaction (ASR) affects numerous concrete structures worldwide. However, the intervention options for ASR in existing structures are limited. Lithium is proposed to suppress expansion. In this paper, an investigation on two-chamber lithium migration as treatment against ASR is presented. First, the influence of different levels of ASR development on lithium migration is studied. Results show that ASR development, if not followed by enough crack formation, hinders migration due to increase in resistivity. Second, the effects of different treatments, such as sodium and potassium removal, lithium migration (combined with the associated sodium and potassium removal) and lithium diffusion, on ASR expansion were evaluated. Lithium migration led to the lowest post-treatment expansion levels.

Synthesis of 3D silicon with tailored nanostructure: Influence of morphology on the electrochemical properties

Within this work, monodisperse porous silicon nanospheres have been derived from monodisperse silica nanospheres via two different magnesiothermic reduction routes, namely (i) magnesiothermic reduction using a two-chamber set-up, and (ii) magnesiothermic reduction using NaCl as heat scavenger. Both methods allow a size- and shape-preserving preparation of mesoporous silicon. Crystalline silicon with a particle size of 56nm and a specific surface area of 198m2g−1 and amorphous silicon with a particle size of 35nm and a specific surface area of 623m2g−1 are synthesized using the two chamber and salt assisted routes, respectively. TEM micrographs confirm enhanced porous character of silicon from NaCl assisted route. An unstable electrochemical performance of the crystalline silicon is found, whereas the amorphous Si presents a stable electrochemical behavior.

Direct trans-Selective Ruthenium-Catalyzed Reduction of Alkynes in Two-Chamber Reactors and Continuous Flow

An efficient trans-selective hydrogenation of alkynes under low hydrogen pressure and low reaction temperatures is reported, applying a commercially available ruthenium hydride complex. The developed reaction conditions, which tolerate a variety of functional groups, are carried out in a two-chamber setup with ex situ generated hydrogen. The reaction setup is highly suitable for deuterium labeling. The trans-selective hydrogenation was extrapolated to a transfer hydrogenation protocol, employing a packed bed immobilized ruthenium hydride catalyst in continuous flow with a retention time of only 10 min.

Workaholic ferrets: Does a two-chamber consumer demand study give insight in the preferences of laboratory ferrets (Mustela putorius furo)?

Although provision of environmental enrichment is an effective tool to refine laboratory animal experiments, it is currently unknown which enrichments ferrets prefer. This study aimed to assess the suitability of a closed economy, two-chamber consumer demand set-up to determine ferrets’ preferences for selected enrichments. Twelve female ferrets were housed in a set-up consisting of a home and enrichment chamber (EC) connected by a weighted door. The maximum weights the ferrets pushed for food (MPPfood) and an empty chamber (MPPempty) were determined to evaluate the maximum push capacity of the animals and as a control. Although the ferrets pushed significantly more for food (1325±213g) than for the empty chamber (1169±193g), the weight difference was minor (MPPempty was 89±13% of MPPfood). To evaluate the ferrets’ underlying motivation to push for the empty chamber, a second study was performed in which MPPempty was tested in seven alternative set-ups. The first three set-ups included adapted versions of the standard design (set-up A1, A2 and A3), intended to determine the functional value of the empty chamber. The four other set-ups (set-up B0, B1, B3, B4) aimed to evaluate the attractiveness of the door elements by allowing the ferrets to choose whether or not to use the weighted door to enter EC. Results demonstrated no significant differences in MPPempty between the A-set-ups, indicating that the value of the empty chamber could not be reduced by adapting the set-up. MPPempty reduced when allowing the ferrets free access to EC, demonstrating that the empty chamber had reinforcing properties. Nevertheless, the ferrets were still motivated to use the weighted door despite being granted free access to EC, indicating that the door also has reinforcing properties. The ferrets decreased the use of the weighted door most when, in a set-up with free access to EC, the nest box in the home cage (53±22% of MPPfood) was replaced by a manipulable plastic bucket (26±13% of MPPfood). These results indicate that availability of items in the home chamber may influence the results, which should be taken into account when designing motivation studies similar to the one performed in this study. The lack of differences between MPPfood and MPPempty furthermore demonstrates that the two-chamber set-up is not suitable for evaluating the ferrets’ motivation for enrichments, thus necessitating other alternatives, such as a three- or multi-chamber consumer demand study, to be explored.

An Air-Tolerant Approach to the Carbonylative Suzuki–Miyaura Coupling: Applications in Isotope Labeling

Carbonylative Suzuki-Miyaura coupling conditions have been developed that proceed without the exclusion of oxygen and in the presence of nondegassed and nondried solvents. By adapting the method to a two-chamber setup, the direct handling of carbon monoxide, produced from stable CO precursors, is avoided. The protocol afforded the desired benzophenones with excellent functional group tolerance and in good yields. Substituting the CO precursor, in the CO-producing chamber, with its carbon-13 labeled version generated the corresponding carbon-13 labeled benzophenones. Finally, the developed system was applied in the synthesis and isotope labeling of two pharmaceuticals, nordazepam and Tricor.

Electrode materials for potentiometric hydrogen sensors

Due to their relatively high sensitivity, improved long-term stability, possibilities for miniaturization and low cost products, mixed potential solid electrolyte sensors can be competitive for the in situ measurement of hydrogen trace concentrations in oxygen containing gases. Their response behavior in non-equilibrated oxygen containing gas mixtures is mainly determined by the catalytic activity of the measuring electrode and depends strongly on preparation and measuring conditions. In this work the sensitivity of electrodes made of composites (Au/MeO) has been investigated in hydrogen containing gases in the concentration range φ(H 2) = 0…800 vol.-ppm using a two-chamber setup with Pt-air reference. Electrodes made of Au/Nb 2O 5 composites show the highest sensitivities of up to 20 mV/vol.-ppm at φ(H 2) = 10 vol.-ppm and the lowest catalytic activity for hydrogen oxidation. Selected composite materials were tested additionally in self-heated solid electrolyte sensors with both electrodes exposed to the same atmosphere (gas-symmetrical sensor).

Cell cultures as tools in biopharmacy

A survey is given on a few selected cell culture models that are used for transport studies. They are characterised for growth, transcellular electrical resistance and cytoarchitecture. The importance of standardisation in view of their use as transport models is documented. Their potential for studies on passive permeation and P-glycoprotein-mediated transport is explored and related to published data. Transport studies are presented that were performed in a two-chamber set-up, the Costar ® “vertical diffusion system”. A series of non-homologous compounds showed similar permeability data ( P app) in the different cell cultures. The origin of the cell type had no remarkable influence on passive transcellular permeation. MDCK cells, an epithelial cell line of canine kidney origin, are perfectly suited to screen for passive permeation. They have low expression of transporter proteins and low metabolic activity. In general, they probably represent the best-known epithelial cell line with respect to genetics as well as lipid and protein composition. MDCK cells are easy to handle. Transport experiments can be done between 7 and 14 days after seeding, when the stationary growth phase is reached. To screen for P-glycoprotein substrates, efflux and uptake studies were performed with mdr1-transfected MDCK cells (MDR1-MDCK) in a one-chamber system in the presence or absence of verapamil or cyclosporin A as inhibitor. Evidence is presented why the transfected cells, which express large amounts of P-glycoprotein, are not suitable for two-chamber transport studies.