Porous chitin matrices for tissue engineering: Fabrication and in vitro cytotoxic assessment

A series of porous chitin matrices were fabricated by freezing and lyophilization of chitin gels cast from a 5% N,N-dimethylacetamide (DMAc)/lithium chloride (LiCl) solvent system. The porous chitin matrices were found to have uniform pore structure in the micron range. Scanning electron microscopy (SEM) revealed that the pore size of the porous chitin matrices varied according to the freezing method prior to lyophilization. By subjecting the chitin gels to dry-ice/acetone (−38 °C), the final porous chitin matrix gave pore dimensions measuring 200–500 μm with 69% porosity. A smaller pore dimension of 100–200 μm with 61% porosity was produced when the chitin gels were frozen by liquid nitrogen (−196 °C) and 10 μm pores with 54% porosity were produced when the gels were placed in a freezer (−20 °C) for 20 min. In comparison, lower porosity structures of ca. 10% porosity were obtained from both air-dried and critical point dried chitin gels. Furthermore, a low gel concentration (< 0.5%, w/w) also produced porous morphology by vacuum drying without any freezing and lyophilization. The resulting pore properties influenced the water uptake profile of the materials in water. These porous chitin matrices are found to be non-cytotoxic and to hold promise as potential structural scaffolds for cell growth and proliferation in vitro.     

Adaptation of an assessment system for establishing a River Physical Quality Index and testing its effectiveness with fish‐based metrics in Malaysia

This study shows how the Stream Visual Assessment Protocol Version 2 that originated from United States was readapted to formulate the River Physical Quality Index (RPQI) for Malaysia. The approach emphasizes that it is not necessary to “reinvent the wheel” as globally, there are already a range of established best practices in developed countries to emulate. The proposed RPQI protocol was tested on four eco‐hydrological zones in Kampar River for 18 months to measure and detect temporal and spatial physical impairment induced by natural and anthropogenic factors. To be relevant to the Malaysian context, local fish community structure metrics were deployed to test and validate RPQI sensitivity and effectiveness. The results showed that RPQI values were able to reflect river physical degradation and correlated strongly with most fish‐based metrics. However, the RPQI values were weakly linked to fish population abundance and evenness metrics. The results implied that species niche responses need to be considered when applied for testing river assessment system, particularly when introduced species are present. The novel insights provided herein are constructive to inform similar endeavours in other Southeast Asia tropical countries for testing river physical assessment systems with biological metrics.     

Recognition and Detection of Diabetic Retinopathy Using Densenet-65 Based Faster-RCNN

Diabetes is a metabolic disorder that results in a retinal complication called diabetic retinopathy (DR) which is one of the four main reasons for sightlessness all over the globe. DR usually has no clear symptoms before the onset, thus making disease identification a challenging task. The healthcare industry may face unfavorable consequences if the gap in identifying DR is not filled with effective automation. Thus, our objective is to develop an automatic and cost-effective method for classifying DR samples. In this work, we present a custom Faster-RCNN technique for the recognition and classification of DR lesions from retinal images. After pre-processing, we generate the annotations of the dataset which is required for model training. Then, introduce DenseNet-65 at the feature extraction level of Faster-RCNN to compute the representative set of key points. Finally, the Faster-RCNN localizes and classifies the input sample into five classes. Rigorous experiments performed on a Kaggle dataset comprising of 88,704 images show that the introduced methodology outperforms with an accuracy of 97.2%. We have compared our technique with state-of-the-art approaches to show its robustness in term of DR localization and classification. Additionally, we performed cross-dataset validation on the Kaggle and APTOS datasets and achieved remarkable results on both training and testing phases.     

A decision tree framework for shot classification of field sports videos

The Journal of Supercomputing - Automated approaches to analyze sports video content have been heavily explored in the last few decades to develop more informative and effective solutions for...     

Effect of domestic cooking methods on total phenolic content,antioxidant activity and sensory characteristics of Hericium erinaceus

This study evaluated the effect of different cooking methods (microwaving, boiling, steaming and stir-frying) on the phenolic acids and antioxidant activity in Hericium erinaceus (HE). The total phenolic content (TPC) of HE decreased after cooking and was in the order of dried (control) > stir-fried > microwaved > steamed > boiled. An increase in antioxidant activity was found in all cooked HE, albeit statistically insignificant (P > 0.05). Gallic acid was reported to be the dominant phenolic acid found in HE extracts in the range of 3.03–49.41 μg g⁻¹ dry weight. Low negative correlations were observed between 2,2-diphenyl-1-picrylhydrazyl (DPPH) and TPC as well as DPPH and gallic acid profile. Sensory data revealed that stir-fried HE received the most favourable response in colour, texture, aroma and flavour attributes. Overall, this study suggested that the method of stir-frying could be used to prepare HE for better retention of gallic acid and antioxidant activity with acceptable sensory characteristics.     

Numerical modelling of deep rolling influence over crankshaft bending and correlation with fatigue behaviour

The requirements for mechanical reliability of automotive crankshafts are continuously increasing, thus pushing the demand for an optimized processing. Nonetheless, the manufacturing‐induced residual stresses at critical sites for fatigue enhancement are not clarified in the state‐of‐the‐art on the topic. In particular, there is a lack of information on the effect of final manufacturing stages to improve the component life endurance, such as deep rolling, in the overall stress state while the component is under operational loads. This study deepens the validation of a finite element deep rolling model under development with the aid of an in‐house developed crankshaft resonance fatigue test rig. The stress state obtained from the deep rolling simulation was input as a predefined stress field for the simulation of operational conditions experimented at the test rig. Test results produced cracks at the fillet radii of the cast iron crankshafts as anticipated. Overlapping the fractography with the simulation's final stress field yielded interesting correlation with the crack morphology. This contributed with a strong indication of the model correctness. Moreover, it can be further implemented to indicate whether the process parameters such as roller force and angle are fully optimized for each particular crankshaft application.     

Heat transfer analysis on wafer annealing process in semiconductor multi-wafer furnace using CFD simulation

This study employs a three-dimensional numerical model to simulate a vertical furnace for wafer annealing process. For a conventional furnace design, it is revealed that the top 5 pieces of the stacked wafers are exposed to lower temperatures, approximately 3–5 % lower than the operating heater temperature. Temperature distribution and the heat losses from the furnace, especially on the heat dissipated through the top header and the process door of the furnace chamber, are examined. To reduce the heat losses, furnace design improvements comprised of a thicker top header and a better thermal insulated process door are recommended. With such implementations, up to 28 % and 22 % reduction of heat dissipation through the top header and the process door, respectively, could be attained. In addition, the design of the boat cover is found to influence the temperature uniformity across the stacked wafers. To attain better temperature uniformity at the top region of stacked wafers, a furnace with a full boat cover is thus recommended.

     

File migration and file replication: a symbiotic relationship

Much of the past research on file migration and file replication has examined these two resource management strategies in isolation or in an environment where they do not work together. We establish through simulation that these two strategies can be utilized simultaneously to potentially provide significant performance benefits over a system without file migration or replication. File replication can be viewed as a natural extension to file migration, and thus, we derive a dynamic file replication policy based on an established file migration heuristic: a file is migrated (or replicated) whenever a reduction in total mean response time of the file requests currently in the affected storage sites can be achieved. Through our performance model, we use simulation to establish the conditions under which our file migration/replication policies are beneficial in a distributed file system