Advanced Materials Research Vol. 925

Abstract: In this study, the dependence of gamma-ray absorption coefficient on the particulate matter sizes of steel slag, iron fillings and steel balls incorporated concrete were examined. The contents of these fillers in concrete mix was kept constant to 35 wt. %. Only the filler particle size was varied during the tests. The particle size ranged from 0.2mm to 1mm for steel slags and the iron fillings and from 2.5mm to 10mm for the steel balls.The concrete samples were assessed for their anti-radiation attenuation coefficient properties. The attenuation measurements were performed using gamma spectrometer of NaI (Tl) detector. The utilized radiation source was Cs137 radioactive element with photon energy of o.662 MeV. The results showed that gamma-ray attenuation coefficient was inversely proportional to the filler particulate matter size. Likewise the mean free paths for the tested samples were obtained. Maximum linear attenuation coefficient of 1.102±0.263cm-1 was attained for the iron filling.The iron balls and the steel slags showed much inferior values. The concrete incorporates iron filings afforded the best shielding effect. The density, microstructure, homogeneity and particulate distribution of the concrete samples were examined and evaluated using different metallographic, microscopic and measurement facilities.

Abstract: Aligned ZnO nanorods were synthesized on a polyethylene naphthalate (PEN) substrates using a chemical bath deposition method. The growth temperature and precursor concentration were 95 °C and 0.025 M, respectively. The effects of growth duration (2 h to 8 h) on the optical and structural properties of the obtained ZnO nanorods on seed layer ZnO/PEN substrate were then investigated using X-ray diffraction, field-emission scanning electron microscopy (FESEM), and photoluminescence (PL) spectroscopy at room temperature. The high intensity of (002) peak compared with (100) and (101) in the X-ray diffraction (XRD) pattern demonstrated that the ZnO nanorods grown for 6.5 h had more vertical higher crystal quality than the samples grown for other durations. The average diameter of ZnO nanorods grown on PEN substrates increased from 19 nm to 45 nm with increased growth duration from 2 h to 8 h, respectively.

Abstract: Zinc sulfide (ZnS) has been reported to act as a photocatalyts to reduce water to hydrogen. However, ZnS could not work under visible light irradiation due to its large band gap energy. In order to improve the performance of ZnS, Ga and Sn were doped to ZnS. The series of Ga (0.1),Sn (x)-ZnS with various amounts of Sn (x) was prepared by hydrothermal method. XRD patterns suggested that the addition of Ga might reduce the crystallinity of ZnS, suggesting that Ga might inhibit the crystal growth or agglomeration of ZnS. On the other hand addition of Sn did not much affect the structure of the Ga (0.1)-ZnS. The DR UU-visible spectra confirmed the red shift of the absorption edge with the addition of Ga due to the reduced band gap energy, while the addition of Sn did not much shift the absorption edge of the Ga (0.1)-ZnS to longer wavelength. FESEM images showed that all the prepared samples have sphere-shaped particles and no remarkable change was observed with the addition of Ga or Sn. The photocatalytic hydrogen production from water was carried out at room temperature in the presence of sacrificial agent under visible light irradiation. While ZnS did not show activity under visible light, all the prepared Ga (0.1)-ZnS and Ga (0.1),Sn (x)-ZnS samples exhibited photocatalytic activity for hydrogen production. The highest hydrogen production was achieved on Ga (0.1),Sn (0.01)-ZnS, which activity was ca. three times higher than that of the single doped Ga (0.1)-ZnS. This study clearly showed that Sn acted as a good co-dopant to increase the photocatalytic activity of Ga (0.1)-ZnS for hydrogen production from water under visible light irradiation.

Abstract: This study is concerned on evaluation of laminated composites of aluminium (Al) sheet and floral foam (FF) under flexural and compression test. Effect of different layers of Al/FF laminated composites was evaluated. Epoxy and hardener was used as the adhesive to bind the surface between the Al sheet and FF. The information on the functional group that exists in FF during the formation of the foam was verified by Fourier Transform Infrared Spectroscopy (FTIR) analysis. From flexural and compression test, the mechanical properties decreased with the increasing number of layers of Al/FF laminated composites. The load cannot be distributed uniformly across the composite layer thus results in failure. Optical Microscope (OM) was used to see the adhesion between the layers of Al/FF laminated composites. One layer (1L) of Al/FF shows good adhesion while for four layer (4L) of the composites show phase separation and the excess adhesive around the interface. This shows that the adhesion between the layers also contribute to the failure of the laminated composite. FTIR analysis shows that the FF consists of amine group (at 3587.95 cm^-1), alcohol group (at 3305.35 cm^-1) and alkyl group (>900 cm^-1) which is the main functional group found in polyurethane foam.

Abstract: Nitrous oxide is generally emitted from industry through fossil fuel combustion thus giving adverse effect to human health and environments. Catalytic converter is the common method used to neutralize this hazardous gas but the high cost of precious metals had limited its application. Nanotitania could neutralize nitrous oxide by the photocatalytic phenomenon and the material is effective as it has small band gap energy and large surface area. In this study, we produced both anatase and rutile crystalline phase nanotitania from a local titanium mineral as the starting material. A significant improvement to the properties of our nanotitania is due to the present of naturally doped neodymium and zirconium ions that are present in the titanium mineral. This make the band gaps for both anatase and rutile to be smaller and effective in photocatalytic process. Three different nanotitania formulations, pure anatase, pure rutile and mixed rutile and anatase phases, were tried in the study and the results showed that all these three formulations were able to neutralize the nitrous oxide within a very short duration. Comparative study was then performed with a blank sample and the result shows there is still significant amount of nitrous oxide present after the 2 hours run.

Abstract: Effect of filler loading on tensile properties, swelling behavior, and XRD characteristic of R-HDPE/tyre dust (TD) composites and R-HDPE/chicken feather fibers (CFF) composites were studied. The both composites were prepared with Brabender Plasticorder at 160°C and rotor speed of 50 rpm. The R-HDPE/TD composites gave a greater value of tensile strength, and swelling behavior resistance compared to R-HDPE/CFF composites. X-ray diffraction analysis shows the R-HDPE/TD composites have lower value of interparticle spacing (d) than R-HDPE/CFF composites. This indicated better interaction between tyre dust and R-HDPE matrix. Keywords: Chicken feather fiber, recycled high density polyethylene, tyre dust

Abstract: Gracilaria sp. is one of macroalgae that contain high amount of sugar especially galactose. This galactose can be fermented into bioethanol by galactose-consuming microbes similar to the widely known ethanol production by yeast S.cerevisae. Hence the main objective of this study is to isolate galactose consuming microbes which capable of fermenting galactose into bioethanol. For this purpose, microbes-containing sample from seaweed culture were grown on galactose agar and tested for their survival as well as ethanol production capability. Seven isolated microbes belong to fungi and bacteria species were tested for their capability in fermenting galactose to produce ethanol. The concentrations of ethanol that have been produced by isolated microbes were analyzed by dichromate method whereas the consumption of galactose was determined by Dinitrosalicyclic acid (DNS) method. It was found that ethanol production resulted from fermentation by S1, S2, S3 and S4 were 0.80% (w/v), 0.74% (w/v), 0.81% (w/v) and 0.85% (w/v) respectively. Identification of these strains, as well as optimization of their ethanol fermentation are undergoing in our laboratory.

Abstract: Cadmium is one of the most toxic metals affecting man, animals, and plants. It is considered one of the priority pollutants, its excretion from the body is very low, and it has synergistic toxicity with other metals. Therefore, cadmium from surface water and wastewater where the cadmium level is high must be treated. This work was done to study the biosorption of Cd (II) from water using Moringa oleifera leaves, as a natural, low cost biosorbent, and environmentally friendly without any modification. The dosage and the particle size of the natural biosorbent were studied as well as the concentration of Cd (II), and pH. The synthetic water with initial turbidity of 200 NTU was used and the Cd (II) concentration was 1ppm, and 3ppm. Different dosages of Moringa oleifera leaves powder of (0.10 to 10 g/L) were added with different particle size of Moringa oleifera leaves (<125, <250, <500, and >500 μm) at room temperature. The AAS was used to measure the residual Cd (II) in the supernatant after treatment with Moringa oleifera leaves powder. It was observed that the removal of Cd (II) was increased by increasing the natural biosorbent dosage, while the particle size and the pH has no effect on the removal efficiency. Therefore, it is concluded that the Moringa oleifera leaves powder can be used as a natural biosorbent without any chemical modification and can be used directly after grinding without sieving to different sizes. The best removal of 1ppm, and 3ppm Cd (II) was at dosage of 8g/L, and 10g/L from fresh grinded leaves, respectively.

Abstract: Herein we report the first example of benzene-1,3,5-tricarboxamide bearing hydrophobic aminododecane side chains (1) which spontaneously forms supramolecular network by a hydrogen bonding interaction. The compound 1 was synthesized by Schotten-Baumann reaction of 1,3,5-benzenetricarbonyl trichloride and 1-aminododecane in the presence of N,N-diisopropylethylamine. Nuclear Magnetic Resonance (NMR), Mass Spectrometry (MS), and Fourier Transform Infrared (FTIR) spectroscopies have proved the successful synthesis of 1 in 93% as white powder solid. The supramolecular organization was successfully utilized for sensing of nitrate anions by deformation of the hydrogen bonding to form inactive nitroso groups.

Abstract: Gold nanoparticles (AuNPs) having particle size less than 10 nm can exhibit enhancement of surface area to give high activity such as in catalytic reaction. However, it is hard to synthesize AuNPs with small particle size due to the strong agglomeration. Herein we report that channels of mesoporous silica synthesized via the template sol-gel synthesis can be used to prepare AuNPs by calcination method. Mesoporous silica with an interpore distance of 4.1 nm was successfully fabricated as transparent thin film by using an amphiphilic trinuclear gold (I) pyrazolate complex as a template for the sol-gel synthesis. Upon calcination at 450 °C for 3 h, silica film nanocomposites showed red-shifting of surface plasmon resonance (SPR) bands from 518 (AuNPs from the bulk) to 544 nm owing to decreasing of the average particle size. The formation of AuNPs was also supported by the appearance of diffraction peaks of d₁₁₁ at 2θ = 38.20° having a cubic phase. Moreover, transmission electron microscope (TEM) images and X-ray diffraction (XRD) peaks also showed smaller and more homogenous distribution of AuNPs.