Anisotropic transport of microalgae Chlorella vulgaris in microfluidic channel

In this work, we study the regional dependence of transport behavior of microalgae Chlorella vulgaris inside microfluidic channel on applied fluid flow rate. The microalgae are treated as spherical naturally buoyant particles. Deviation from the normal diffusion or Brownian transport is characterized based on the scaling behavior of the mean square displacement(MSD) of the particle trajectories by resolving the displacements in the streamwise(flow) and perpendicular directions.The channel is divided into three different flow regions, namely center region of the channel and two near-wall boundaries and the particle motions are analyzed at different flow rates. We use the scaled Brownian motion to model the transitional characteristics in the scaling behavior of the MSDs. We find that there exist anisotropic anomalous transports in all the three flow regions with mixed sub-diffusive, normal and super-diffusive behavior in both longitudinal and transverse directions.     

Flexural behavior of reinforced-concrete sandwich composites

An experimental investigation was carried out to examine the flexural behavior of rectangular sandwich composites and to determine appropriate structural applications for such constructions. The sandwich cores were composed of nonpermeated, expanded aluminum honeycomb and the facings consisted of concrete mortar. Appropriate theories that predict the behavior of such composites were presented and compared to experimental data. All specimens had facing thicknesses of 1 in., core thicknesses of 1 in., 2 in. and 3 in.; core-cell size of 1/8 in. and 3/8 in.; while four different core foil gages were considered for each cell size. The lower facing was either plain concrete mortar or reinforced with steel wires. The large cell-size specimen displayed better bond characteristics and produced better and more stable experimental data. Reasonable agreement was found between the observed and computed flexural stresses. The deflections at midspan were in good agreement with the theoretically predicted deflections in all of the specimens, with or without reinforcement. Regardless of cell size, density, core thickness or reinforcement, the observed midspan and quarterspan deflections of the top facing were approximately twice the deflections at the corresponding locations on the lower facing. The ultimate loads increased as the core thickness and the core density increased. The influence of flexural rigidity of the core can be neglected.     

Effect of axial loads on concrete-mortar sandwich composites

Experimental investigations were conducted to examine the behavior of concrete sandwich composites under compressive and tensile loads. The sandwich cores were composed of nonpermeated, expanded aluminum honeycomb and the facings consisted of concrete mortar. Appropriate theories that predict the behavior of such composites were presented and compared with experimental data. All specimens had facing thicknesses of 1 in. (25.4 mm), core thicknesses of 1, 2 and 3 in. (25.4, 50.8 and 76.2 mm); core-cell size of 1/8 and 3/8 in. (3.2 and 9.5 mm); while four different core foil gages were considered for each size. The facings were either plain concrete mortar or reinforced with steel wires. The large-core-cell-size specimen displayed better bond characteristics and produced more consistent experimental data. The ultimate strengths of both compressive and tensile specimens were not affected by the core-cell size, core thickness, or core density. Axial compressive loads were carried by the facing area while tensile loads were by the reinforcements in the facings. The buckling waves were developed due to the wrinkling of the facings. The buckling waves in the two facings were independent of each other and the overall wave pattern was antisymmetrical.     

Plasmonic Colloidosomes as Three‐Dimensional SERS Platforms with Enhanced Surface Area for Multiphase Sub‐Microliter Toxin Sensing

Colloidosomes are robust microcapsules attractive for molecular sensing because of their characteristic micron size, large specific surface area, and dual‐phase stability. However, current colloidosome sensors are limited to qualitative fluorogenic receptor‐based detection, which restrict their applicability to a narrow range of molecules. Here, we introduce plasmonic colloidosome constructed from Ag nanocubes as an emulsion‐based 3D SERS platform. The colloidosomes exhibit excellent mechanical robustness, flexible size tunability, versatility to merge, and ultrasensitivity in SERS quantitation of food/industrial toxins down to sub‐femtomole levels. Using just 0.5 μL of sample volumes, our plasmonic colloidosomes exhibit >3000‐fold higher SERS sensitivity over conventional suspension platform. Notably, we demonstrate the first high‐throughput multiplex molecular sensing across multiple liquid phases.     

Crude Cellulase from Oil Palm Empty Fruit Bunch by Trichoderma asperellum UPM1 and Aspergillus fumigatus UPM2 for Fermentable Sugars Production

Cellulase is an enzyme that converts the polymer structure of polysaccharides into fermentable sugars. The high market demand for this enzyme together with the variety of applications in the industry has brought the research on cellulase into focus. In this study, crude cellulase was produced from oil palm empty fruit bunch (OPEFB) pretreated with 2 % NaOH with autoclave, which was composed of 59.7 % cellulose, 21.6 % hemicellulose, and 12.3 % lignin using Trichoderma asperellum UPM1 and Aspergillus fumigatus UPM2. Approximately 0.8 U/ml of FPase, 24.7 U/ml of CMCase and 5.0 U/ml of β-glucosidase were produced by T. asperellum UPM1 at a temperature of 35 °C and at an initial pH of 7.0. A 1.7 U/ml of FPase, 24.2 U/ml of CMCase, and 1.1 U/ml of β-glucosidase were produced by A. fumigatus UPM2 at a temperature of 45 °C and at initial pH of 6.0. The crude cellulase was best produced at 1 % of substrate concentration for both T. asperellum UPM1 and A. fumigatus UPM2. The hydrolysis percentage of pretreated OPEFB using 5 % of crude cellulase concentration from T. asperellum UPM1 and A. fumigatus UPM2 were 3.33 % and 19.11 %, with the reducing sugars concentration of 1.47 and 8.63 g/l, respectively.     

ZIF‐Induced d‐Band Modification in a Bimetallic Nanocatalyst: Achieving Over 44 % Efficiency in the Ambient Nitrogen Reduction Reaction

The electrochemical nitrogen reduction reaction (NRR) offers a sustainable solution towards ammonia production but suffers poor reaction performance owing to preferential catalyst–H formation and the consequential hydrogen evolution reaction (HER). Now, the Pt/Au electrocatalyst d‐band structure is electronically modified using zeolitic imidazole framework (ZIF) to achieve a Faradaic efficiency (FE) of >44 % with high ammonia yield rate of >161 μg mg_cat^?1 h^?1 under ambient conditions. The strategy lowers electrocatalyst d‐band position to weaken H adsorption and concurrently creates electron‐deficient sites to kinetically drive NRR by promoting catalyst–N₂ interaction. The ZIF coating on the electrocatalyst doubles as a hydrophobic layer to suppress HER, further improving FE by >44‐fold compared to without ZIF (ca. 1 %). The Pt/Au‐N_ZIF interaction is key to enable strong N₂ adsorption over H atom.     

Online Flowing Colloidosomes for Sequential Multi-analyte High-Throughput SERS Analysis

3D plasmonic colloidosomes are superior SERS sensors owing to their high sensitivity and excellent tolerance to laser misalignment. Herein, we incorporate plasmonic colloidosomes in a microfluidic channel for online SERS detection. Our method resolves the poor signal reproducibility and inter-sample contamination in the existing online SERS platforms. Our flow system offers rapid and continuous online detection of 20 samples in less than 5 min with excellent signal reproducibility. The isolated colloidosomes prevent cross-sample and channel contamination, allowing accurate quantification of samples over a concentration range of five orders of magnitude. Our system demonstrates high-resolution multiplex detection with fully preserved signal and Raman features of individual analytes in a mixture. High-throughput multi-assay analysis is performed, which highlights that our system is capable of rapid identification and quantification of a sequence of samples containing various analytes and concentrations.     

Expulsion of bovine serum albumin from the air/water interface by a sparingly soluble lecithin lipid

Dynamic surface tensiometry, ellipsometry, and infrared reflection-absorption spectroscopy (IRRAS) were used to study the dynamic adsorption and surface tensions of dilauroylphosphatidylcholine (DLPC) in the presence of bovine serum albumin (BSA). Results show that the equilibrium adsorbed layers consist mostly of DLPC, which can produce dynamic surface tensions (1 mN/m) as low as the more successful lung surfactant replacement formulations. When the aqueous surface expands and contracts sinusoidally, BSA can coadsorb and lead to slightly higher dynamic surface tensions than when DLPC is alone. Similar results were obtained with BSA and sodium myristate [McClellan and Franses, Colloids Surf. B 30 (2003) 1]. Expulsion of the BSA in the layer by DLPC can take from 5 to 15 min, depending on relative concentrations and history of solute addition. This is shown by tensiometry measurements on mixtures, and also by injecting aqueous DLPC underneath adsorbed BSA layers and probing the surface layer with ellipsometry and IRRAS. Albumin layers from buffer solutions aged up to 30 h can be expelled by DLPC. In pure water, there is an initial enhancement in protein adsorption after the DLPC is injected. This can be explained by the hypothesis that DLPC molecules bind with BSA molecules to form a hydrophobic lipoprotein complex, which is more hydrophobic than the protein itself. Since DLPC produces lower surface energy than BSA and--being slightly soluble--adsorbs to the surface by a molecular mechanism, it fulfills the thermodynamic and dynamic requirements for expelling the BSA from the surface. The results have implications for minimizing lung surfactant inhibition by serum proteins, as it occurs in the cases of adult or acute respiratory distress syndrome.