Intercomparison of techniques for estimation of sedimentation rate in the Sabah and Sarawak coastal waters

A total of eight sediment cores with 50 cm length were taken in the Sabah and Sarawak coastal waters using a gravity corer in 2004 to estimate sedimentation rates using four mathematical models of CIC, Shukla-CIC, CRS and ADE. The average of sedimentation rate ranged from 0.24 to 0.48 cm year^?1, which is calculated based on the vertical profile of ²¹⁰Pb_ex in sediment core. The finding also showed that the sedimentation rates derived from four models were generally shown in good agreement with similar or comparable value at some stations. However, based on statistical analysis of paired sample t-test indicated that CIC model was the most accurate, reliable and suitable technique to determine the sedimentation rate in the coastal area.     

Radioactivity of plutonium isotopes, <Superscript>137</Superscript>Cs and their ratio in sediment,seawater and biota from the east coast of Peninsular Malaysia

This study with sampling expeditions of marine sediment, seawater and biota were performed at 30 stations within Malaysian Exclusive Economic Zone (EEZ). A total of >400 samples were collected to determine the activity concentration of anthropogenic radionuclides (^239+240Pu, ¹³⁷Cs) and their activity ratio (^239+240Pu/¹³⁷Cs) in sediments, seawater and biota. The purpose of this study was to determine the concentration levels for these radionuclides and to evaluate any occurrence of radioactive contamination. Sediment cores were obtained using multicorer device, while water samples via co-precipitation techniques and biota was purchased from local fishermen. The activity concentrations of ^239+240Pu in sediment, seawater and biota were ranged 0.21–0.45 Bq/kg dry wt., 2.33–7.95 mBq/m³ and <0.008 Bq/kg fresh wt., respectively. Meanwhile, the values of ¹³⁷Cs were ranged <1.00–2.71 Bq/kg dry wt. in sediment, 3.40–5.89 Bq/m³ in seawater and <0.05–0.41 Bq/kg fresh wt. in biota, respectively. Activity ratios of ^239+240Pu to ¹³⁷Cs obtained seem to confirm that these artificial radioactivities were mainly due to global nuclear fallout.     

Seeding Molecular Rotators on a Passivated Silicon Surface

Thermally activated rotation of single molecules adsorbed on a silicon‐based surface between 77 and 150 K has been successfully achieved. This remarkable phenomenon relies on a nanoporous supramolecular network, which acts as a template to seed periodic molecule rotors on the surface. Thermal activation of rotation has been demonstrated by STM experiments and confirmed by theoretical calculations.     

Synthesis,Characterization, and Photoluminescence Properties of Silver(I) Metal‐Organic Polymers with Nanochannels Based on 2‐Sulfoterephthalic Acid and Di(pyridin‐2‐yl)amine Ligands

Two new silver(I) 3D coordination polymers, namely [Ag₃(2‐stp)(dpa)]_n ( 1 ) and {[Ag₂(2‐stp)(H₂O)]?Hdpa}_n ( 2 ) (2‐NaH₂stp=sodium 2,5‐dicarboxysulfonate, dpa=di(pyridine‐2‐yl)amine) were synthesized. The complexes were characterized by elemental analysis, FT‐IR spectra, thermogravimetric analyses (TGA), and single‐crystal X‐ray diffraction. In complex 1 , three neighboring Ag ions are bridged by N‐ and O‐atom, forming a 3D coordination network. The molecular structure of 2 is cation? anion species, forming 3D host? guest supramolecular network with the [Hdpa]⁺ cations encapsulated in the nanochannels. The photoluminescence properties of the complexes were also investigated in the solid state at room temperature.     

CH4 reforming with CO2 for syngas production over La2O3 promoted Ni catalysts supported on mesoporous nanostructured γ-A12O3

Nanostructured -y-A12O3 with high surface area and mesoporous structure was synthesized by sol-gel method and employed as catalyst support for nickel catalysts in methane reforming with carbon dioxide. The prepared samples were characterized by XRD, N2 adsorption-desorption, TPR, TPO, TPH, NH3-TPD and SEM techniques. The BET analysis showed a high surface area of 204 m2.g-1 and a narrow pore-size distribution centered at a diameter of 5.5 nm for catalyst support. The BET results revealed that addition of lanthanum oxide to aluminum oxide decreased the specific surface area. In addition, TPR results showed that addition of lanthanum oxide increased the reducibility of nickel catalyst. The catalytic evaluation results showed an increase in methane conversion with increasing lanthanum oxide to 3 mol% and further increase in lanthanum content decreased the catalytic activity. TPO analysis revealed that the coke deposition decreased with increasing lanthanum oxide to 3 mol%. SEM and TPH analyses confirmed the formation of whisker type carbon over the spent catalysts. Addition of steam and Oxide to drv reformin feed increased the methane conversion and led to carbon free ooeration in combined orocesses.     

CH_4 reforming with CO_2 for syngas production over La_2O_3 promoted Ni catalysts supported on mesoporous nanostructured γ-Al_2O_3

Nanostructured γ-Al2O3 with high surface area and mesoporous structure was synthesized by sol-gel method and employed as catalyst support for nickel catalysts in methane reforming with carbon dioxide. The prepared samples were characterized by XRD, N2adsorption-desorption,TPR, TPO, TPH, NH3-TPD and SEM techniques. The BET analysis showed a high surface area of 204 m2 g-1and a narrow pore-size distribution centered at a diameter of 5.5 nm for catalyst support. The BET results revealed that addition of lanthanum oxide to aluminum oxide decreased the specific surface area. In addition, TPR results showed that addition of lanthanum oxide increased the reducibility of nickel catalyst. The catalytic evaluation results showed an increase in methane conversion with increasing lanthanum oxide to 3 mol% and further increase in lanthanum content decreased the catalytic activity. TPO analysis revealed that the coke deposition decreased with increasing lanthanum oxide to 3 mol%. SEM and TPH analyses confirmed the formation of whisker type carbon over the spent catalysts. Addition of steam and O2 to dry reforming feed increased the methane conversion and led to carbon free operation in combined processes.     

New Polydentate Trimethylsilyl Chalcogenide Reagents for the Assembly of Polyferrocenyl Architectures

A series of polychalcogenotrimethylsilane complexes Ar(CH₂ESiMe₃)_n, (Ar=aryl; E=S, Se; n=2, 3, and 4) can be prepared from the corresponding polyorganobromide and M[ESiMe₃] (M=Na, Li). These represent the first examples of the incorporation of such a large number of reactive ?ESiMe₃ moieties onto an organic molecular framework. They are shown to be convenient reagents for the preparation of the polyferrocenylseleno‐ and thioesters from ferrocenoyl chloride. The synthesis, structures, and spectroscopic properties of the new silyl chalcogen complexes 1,4‐(Me₃SiECH₂)₂(C₆Me₄) (E=S, 1 ; E=Se, 2 ), 1,3,5‐(Me₃SiECH₂)₃(C₆Me₃) (E=S, 3 ; E=Se, 4 ) and 1,2,4,5‐(Me₃SiECH₂)₄(C₆H₂) (E=S, 5 ; E=Se, 6 ) and the polyferrocenyl chalcogenoesters [1,4‐{FcC(O)ECH₂}₂(C₆Me₄)] (E=S, 7 ; E=Se, 8 ), [1,3,5‐{FcC(O)ECH₂}₃(C₆Me₃)] (E=S, 9 ; E=Se, 10 ) and [1,2,4,5‐{FcC(O)ECH₂}₄(C₆H₂)] (E=S, 11 illustrated; E=Se, 12 ) are reported. The new polysilylated reagents and polyferrocenyl chalcogenoesters have been characterized by multinuclear NMR spectroscopy (¹H, ¹³C, ⁷⁷Se), electrospray ionization mass spectrometry and, for complexes 1 , 2 , 3 , 4 , 7 , 8 , and 11 , single‐crystal X‐ray diffraction. The cyclic voltammograms of complexes 7 – 11 are presented.     

A new alkylated benzoquinone from rhizomes of Iris kumaonensis

A novel alkylated unsaturated p-benzoquinone designated as 3-[(z)-12'-heptadecenyl]-2-hydroxy-5-methoxy-1,4-benzoquinone was isolated from hexane extract of the rhizomes of Iris kumaonensis and it's structure was confirmed by extensive spectroscopic analysis, IR, MS, HREIMS, 1D, 2D NMR and comparison with the literature data of known compounds.