Synthesis of High‐Performance Pebax®‐1074/DD3R Mixed‐Matrix Membranes for CO2/CH4 Separation

This work deals with the incorporation of deca‐dodecasil 3 rhombohedral (DD3R) zeolite as an inorganic filler into the Pebax®‐1074‐based polymer matrix to enhance the performance of the pure polymeric membrane in CO₂/CH₄ separation. The membranes were fabricated with different concentrations of DD3R. Separation performances of the membranes were investigated at various feed pressures and temperatures. Scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), and differential scanning calorimetry (DSC) analysis of the prepared membranes were performed. In the best case, selectivity for CO₂/CH₄ separation was improved, while the permeability decreased. Membranes with 1 and 5 wt % DD3R were located in the acceptable region beyond the Robeson plot (1991) for CO₂/CH₄ gas pairs.     

Learning multiple experiences useful visual features for active maps localization in crowded environments

Crowded urban environments are composed of different types of dynamic and static elements. Learning and classification of features is a major task in solving the localization problem in such environments. This work presents a gradual learning methodology to learn the useful features using multiple experiences. The usefulness of an observed element is evaluated by a scoring mechanism which uses two scores – reliability and distinctiveness. The visual features thus learned are used to partition the visual map into smaller regions. The robot is efficiently localized in such a partitioned environment using two-level localization. The concept of active map (AM) is proposed here, which is a map that represents one partition of the environment in which there is a high probability of the robot existing. High-level localization is used to track the mode of the AMs using discrete Bayes filter. Low-level localization uses a bag-of-words model to retrieve images and accurately localize the robot. The pose of the robot is the one retrieved from the AM that has maximum a posteriori. Experiments have been conducted on a unique highly crowded data-set collected from Indian roads. The results support the proposed method due to speed and localization accuracy.     

Synthesis of Novel Series of Benzothieno [2,3-d] Pyrimidine Derivatives, Promising Anticancer Agents

An extension of the authors＇ previous discovery of in vitro antitumor activity of substituted thino [2,3-d] prymidine derivatives is reported. The synthesis of some new spirothino [2,3-d] prymidine （4a-f）, imidazolidin, substituted prymidinyl and substituted thiazolidine thino [2,3-d] prymidine derivatives have been described. Thirteen of the obtained compounds were selected by the NCI and evaluated for their in vitro anticancer activity. Seven of the investigated compounds, 4a, 8a, 9a, （12a, b）, 14a and 15a, displayed high anticancer activity in the primary assay. These compounds have been selected for a full anticancer screening against a 60-cell panel assay where they showed non-selective broad spectrum and promising activity against all cancer cell lines. Compounds 12a and 12b proved to be the active members in this study compared to 5-fluorouracil and cyclophosphamide as reference drugs, respectively. Compounds 12a and 12b were identified as promising lead compounds, evaluated for their in-vitro antitumor activity.     

An integrated system for hydrogen and methane production during landfill leachate treatment

The patent-pending integrated waste-to-energy system comprises both a novel biohydrogen reactor with a gravity settler (Biohydrogenator), followed by a second stage conventional anaerobic digester for the production of methane gas. This chemical-free process has been tested with a synthetic wastewater/leachate solution, and was operated at 37 °C for 45 d. The biohydrogenator (system (A), stage 1) steadily produced hydrogen with no methane during the experimental period. The maximum hydrogen yield was 400 mL H₂/g glucose with an average of 345 mL H₂/g glucose, as compared to 141 and 118 mL H₂/g glucose for two consecutive runs done in parallel using a conventional continuously stirred tank reactor (CSTR, System (B)). Decoupling of the solids retention time (SRT) from the hydraulic retention time (HRT) using the gravity settler showed a marked improvement in performance, with the maximum and average hydrogen production rates in system (A) of 22 and 19 L H₂/d, as compared with 2–7 L H₂/d in the CSTR resulting in a maximum yield of 2.8 mol H₂/mol glucose much higher than the 1.1–1.3 mol H₂/mol glucose observed in the CSTR. Furthermore, while the CSTR collapsed in 10–15 d due to biomass washout, the biohydrogenator continued stable operation for the 45 d reported here and beyond. The methane yield for the second stage in system (A) approached a maximum value of 426 mL CH₄/gCOD removed, while an overall chemical oxygen demand (COD) removal efficiency of 94% was achieved in system (A).     

Effect of organic loading on a novel hydrogen bioreactor

This study investigated the impact of six organic loading rates (OLR) ranging from 6.5 gCOD/L-d to 206 gCOD/L-d on the performance of a novel integrated biohydrogen reactor clarifier systems (IBRCSs) comprised a continuously stirred reactor (CSTR) for biological hydrogen production, followed by an uncovered gravity settler for decoupling of solids retention time (SRT) from hydraulic retention time (HRT). The system was able to maintain a high molar hydrogen yield of 2.8 mol H₂/mol glucose at OLR ranging from 6.5 to 103 gCOD/L-d, but dropped precipitously to approximately 1.2 and 1.1 mol H₂/mol glucose for the OLRs of 154 and 206 gCOD/L-d, respectively. The optimum OLR at HRT of 8 h for maximizing both hydrogen molar yield and volumetric hydrogen production was 103 gCOD/L-d. A positive statistical correlation was observed between the molar hydrogen production and the molar acetate-to-butyrate ratio. Biomass yield correlated negatively with hydrogen yield, although not linearly. Analyzing the food-to-microorganisms (F/M) data in this study and others revealed that, both molar hydrogen yields and biomass specific hydrogen rates peaked at 2.8 mol H₂/mol glucose and 2.3 L/gVSS-d at F/M ratios ranging from 4.4 to 6.4 gCOD/gVSS-d. Microbial community analysis for OLRs of 6.5 and 25.7 gCOD/L-d showed the predominance of hydrogen producers such as Clostridium acetobutyricum, Klebsiella pneumonia, Clostridium butyricum, Clostridium pasteurianum. While at extremely high OLRs of 154 and 206 gCOD/L-d, a microbial shift was clearly evident due to the coexistence of the non-hydrogen producers such as Lactococcus sp. and Pseudomonas sp.     

Tactile Rendering With Shape-Memory-Alloy Pin-Matrix

This paper presents a novel pin-matrix tactile-display device that exhibits some advantageous features for the blind: low cost, lightweight, compactness, and high portability. The prototype consists of 64 tactile pins actuated by shape memory alloys with 2.6-mm spatial resolution (Braille-like). Unlike existing devices, the full display weighs only 200 g, and its compact dimensions make it easy to carry. A technical overview of the system is presented, as well as preliminary results on shape recognition, to evaluate its performance on tactile rendering.     

Wake capturing in potential flow calculations

Summary In this paper, we present a formulation for irrotational, isentropic flows in terms of velocity components which is equivalent to the classical potential equation, except the wake is not fixed and it is captured as part of the solution with no special treatment. Preliminary numerical results are presented to validate this new approach.