Optimization of a one-step direct process for biodiesel production from blended sewage sludge

Biodiesel production from blended sewage sludge (BSS) by a one-step direct process was investigated, and optimal conditions for this process were determined. The one-step direct process comprises extraction of lipids from BSS and simultaneous transesterification of these lipids with methanol. Among the organic solvents evaluated, pure methanol showed higher biodiesel yields compared with other solvents or solvent mixtures. The optimum conditions determined included 10 mL of methanol/g-BSS, 0.7% (g/g-BSS) of H₂SO₄, 60 °C, 4 h of reaction time and 300 rpm of agitation speed. Under these conditions, biodiesel yield was 3.1% (g-biodiesel/g-BSS), which was 63.2% higher than that obtained under initial conditions, and 24.0%-63.2% higher than those obtained in previous studies.     

Effect of Interfacial Adhesion on the Mechanical Properties of Organic/Inorganic Hybrid Nanolaminates

Two different kinds of organic polyelectrolyte (PE)/inorganic silicate nanolaminates carrying dissimilar interfacial adhesion between the organic and the inorganic layers were prepared using the layer-by-layer self-assembly. To investigate the mechanical behavior of the prepared hybrid films, apparent modulus (E′), hardness (H), and crack length were measured by depth-sensing nanoindentation as well as a microVickers experiment. The fracture toughness of the hybrid films was then calculated based on the measured mechanical values. In the case of forming strong interfacial adhesion between the organic and the inorganic layers (A series), the fracture toughness and the crack resistance of hybrid multilayer films were significantly improved as a result of the redistribution of stress concentration and the dissipation of fracture energy by the plasticity of organic PE layers. On the other hand, samples with relatively low interfacial adhesion between the organic and the inorganic layers (T series) had little effect on the improvement of fracture toughness of the hybrid films.     

Development of banana peel jelly and its antioxidant and textural properties

The principal objectives of this study were to develop a functional jelly product that possesses antioxidant activity and contains dietary fiber, utilizing banana peel, a common banana byproduct, and to evaluate its physicochemical and antioxidant properties to verify the maintenance of its antioxidant property even after cooking for jelly-production. The jelly was produced under the identical conditions of cooking time, temperature, and sugar contents with ordinary jellies, except the addition of banana peel powder (BPP). The hardness, chewiness, and springiness of the produced jellies increased with addition of supplementary banana peel powder. Antioxidant activities of BPP and the produced banana peel jellies were compared through 1,1-diphenyl-2-picrylhydrazyl (DPPH) assay, 2,2′-azino-bis(3-ethylbenzo thiazoline, 6-sulphonic acid) (ABTS) radical scavenging test, and nitrite scavenging activity assay. The antioxidant activities also remained in the jelly after cooking during jelly production. The textural properties, the contents of total dietary fiber, phenolics, and flavonoids, and the antioxidant activities of the jellies were correlated positively with the amount of BPP added for the jellies.     

Effects of the Domain Size on Local d33 in Tetragonal (Na0.53 K0.45Li0.02)(Nb0.8Ta0.2)O3 Ceramics

Lead‐free (Na_0.53K_0.45Li_0.02)(Nb_0.8Ta_0.2)O₃ (NKLNT) was prepared using a conventional cold‐pressing method. A commercial piezoresponse force microscope (PFM) was applied to observe the domain structures of NKLNT ceramics. The typical configuration of the ferroelectric domain was analyzed in abnormal grains with grain sizes that exceeded 40 μm, where tetragonal 90° domains are predominant. The local piezoresponse hysteresis loops were characterized and studied as a function of the domain width (dw) in the range 300–1000 nm. It was found that the amplitude signals increased and the coercive field reduced significantly with a decrease in the domain size. Finally, the local longitudinal piezoelectric coefficient (d₃₃) increased as the domain size decreased.     

Sludge settleability detection using automated SV30 measurement and comparisons of feature extraction methods

The need for automation and measurement technologies to detect the process state has been a driving force in the development of various measurements at wastewater treatment plants. While the number of applications of automation & measurement technologies to the field is increasing, there have only been a few cases where they have been applied to the area of sludge settling. It is not easy to develop an automated operation support system for the detection of sludge settleability due to its site-specific characteristics. To automate the human operator’s daily test and diagnosis work on sludge settling, an on-line SV30 measurement was developed and an automated detection algorithm on settleability was developed that imitated heuristics to detect settleability faults. The automated SV30 measurement is based on automatic pumping with a predefined schedule, the image capture of the settling test with a digital camera, and an analysis of the images to detect the settled sludge height. To detect settleability faults such as deflocculation and bulking from these images, two feature extraction methods were used and their performance was evaluated.     

Effects of Cr and Fe Addition on Microstructure and Tensile Properties of Ti–6Al–4V Prepared by Direct Energy Deposition

The effects of Cr and Fe addition on the mechanical properties of Ti–6Al–4V alloys prepared by direct energy deposition were investigated. As the Cr and Fe concentrations were increased from 0 to 2 mass%, the tensile strength increased because of the fine-grained equiaxed prior β phase and martensite. An excellent combination of strength and ductility was obtained in these alloys. When the Cr and Fe concentrations were increased to 4 mass%, extremely fine-grained martensitic structures with poor ductility were obtained. In addition, Fe-added Ti–6Al–4V resulted in a partially melted Ti–6Al–4V powder because of the large difference between the melting temperatures of the Fe eutectic phase (Ti–33Fe) and the Ti–6Al–4V powder, which induced the formation of a thick liquid layer surrounding Ti–6Al–4V. The ductility of Fe-added Ti–6Al–4V was thus poorer than that of Cr-added Ti–6Al–4V.     

Design of an energy saving oil cooler system using hot gas

According to the development of machine tools to higher speed and multi axes, thermal error which is known to account for about 70% of the total error of machine tools is becoming a serious issue. To reduce thermal error, the heat generating parts of machine tools are cooled down by direct contact with a cooling medium. The medium in most cases is oil, thus, the cooling device is called oil cooler. In this study, an oil cooler system employing hot gas bypass method was developed to improve the performance including energy efficiency of the oil coolers used for ultra-precision machine tools. Through tests, the developed system exhibited high temperature control accuracy of ±0.1°C, and less energy consumption than conventional on/off type (equipped with heater for preventing excessive cooling) by about 45%. The proposed oil cooler system is applicable to semiconductor process, ultra-precision injection molds, as well as ultra-precision machine tools to improve product quality and energy efficiency of production facilities.     

Polymeric calcium phosphate cements incorporated with poly‐γ‐glutamic acid: Comparative study of poly‐γ‐glutamic acid and citric acid

Polymeric calcium phosphate cements (PCPC) derived from biodegradable poly‐γ‐glutamic acid (γ‐PGA) were prepared in an attempt to improve the mechanical strength of calcium phosphate cement (CPC). The characteristics of the PCPCs were compared with those of cement incorporated with citric acid. The diametral tensile and compressive strengths of the CPC incorporated with γ‐PGA were significantly higher than that of cement incorporated with citric acid at equivalent concentrations (P < 0.05). The maximal diametral tensile and compressive strengths of the CPC incubated for 1 week in physiological saline solution were approximately 18.0 and 50.0 MPa, respectively. However, the initial setting time of the PCPC was slower than that of CPC incorporated with citric acid. The formation of ionic complexes between calcium ions and γ‐PGA was observed using FTIR spectroscopy. Hydroxyapatite (HA) formation was retarded by γ‐PGA incorporation according to scanning electronic microscopy (SEM) and powder X‐ray diffraction (XRD) observations. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Numerical prediction of airfoil characteristics in a transonic droplet-laden air flow

A transonic airfoil moving in an air–water droplet two-phase flow is investigated numerically to study the effect of droplet size and volume fraction. The droplets we consider are in the size 1–100 μm and the volume fraction is in 0.01%–10%. A compressible two-fluid model is solved by the WAF-HLL scheme developed earlier by the authors which includes drag force, heat transfer, phase change, and droplet fragmentation of the droplets. The numerical results show that the droplet breakup layer can be extended to a later distance as large as about 60% of a chord length at the trailing edge. Also the droplets have made the shock wave dissolved in compression waves and the airfoil performance seriously deteriorated.