Estimation of sedimentation rates using 210Pb and 210Po at the coastal water of Sabah, Malaysia

Sediment cores were obtained from Teluk Brunei, Sipitang, Teluk Kimanis, Kota Kinabalu and Kuala Penyu at the coastal water of Sabah and analyzed for ²¹⁰Pb and ²¹⁰Po to estimate the sedimentation rates. The calculated sedimentation rates of ²¹⁰Pb and ²¹⁰Po varied from 0.003 to 0.049 cm/y and 0.74 to 8.77 cm/y, respectively. The highest sedimentation rates were determined for ²¹⁰Pb and ²¹⁰Po at stations located at Sipitang (mean: 0.027 cm/y) and Teluk Kimanis (mean: 5.53 cm/y), respectively. The sedimentation rate estimated for ²¹⁰Pb is not fully reliable because the activity of ²²⁶Ra was higher than that of ²¹⁰Pb and bioturbation was active at the sampling stations.     

The Role of Internal Droplet Size on Emulsion Stability and the Extraction Performance of Kraft Lignin Removal from Pulping Wastewater in Emulsion Liquid Membrane Process

It has been discovered that the size of internal droplets in primary emulsion determines emulsion dispersion and stability in emulsion liquid membrane (ELM) process for removal of lignin from pulping wastewater. Generally, primary emulsion contains kerosene, Aliquat 336, sodium bicarbonate, as well as Span 80 as diluent, carrier, internal phase, and surfactant, respectively. Hence, this study had looked into the parameters, including concentration of surfactant, carrier, and stripping agent; emulsification speed and time; as well as agitation speed and time. As a result, the diameter of the smallest droplets (1.4 µm) was formed with maximum lignin extraction (95%), minimum swelling (5%) at 3% (w/v) surfactant concentration, 12,000 rpm of emulsification within 5 minutes, 0.01 M of Aliquat 336, 0.1 M of NaHCO_3, and 250 rpm of extraction within 10 minutes.     

Preparation,Functionality, and Application of Metal Oxide‐coated Noble Metal Nanoparticles

With their remarkable properties and wide‐ranging applications, nanostructures of noble metals and metal oxides have been receiving significantly increased attention in recent years. The desire to combine the properties of these two functional materials for specific applications has naturally prompted research in the design and synthesis of novel nanocomposites, consisting of both noble metal and metal‐oxide components. In this review, particular attention is given to core–shell type metal oxide‐coated noble metal nanostructures (i.e., metal@oxide), which display potential utility in applications, including photothermal therapy, catalytic conversions, photocatalysis, molecular sensing, and photovoltaics. Emerging research directions and areas are envisioned at the end to solicit more attention and work in this regard.

     

Palladium nanoclusters supported on propylurea-modified siliceous mesocellular foam for coupling and hydrogenation reactions

This paper describes the synthesis, characterization and applications of palladium (Pd) nanoparticles supported on siliceous mesocellular foam (MCF). Pd nanoparticles of 2-3 nm and 4-6 nm were used in reactions involving molecular hydrogen (such as hydrogenation of double bonds and reductive amination), transfer hydrogenation of ketones and epoxides, and coupling reactions (such as Heck and Suzuki reactions). They successfully catalyzed all these reactions with excellent yield and selectivity. This heterogeneous catalyst was easily recovered by filtration, and recycled several times without any significant loss in activity and selectivity. The palladium leaching in the reactions was determined to be much less than the FDA-approved limit of 5 ppm. Furthermore, the catalyst can be stored and handled under normal atmospheric conditions. This immobilized catalyst allows for ease of recovery/reuse and minimization of waste generation, which are of great interest in the development of green chemical processes.     

Ramanujan's Eisenstein series and powers of Dedekind's eta-function

In this article, we use the theory of elliptic functions toconstruct theta function identities which are equivalent toMacdonald's identities for A₂, B₂ and G₂. Using these identities,we express, for d = 8, 10 or 14, certain theta functions inthe form ^d()F(P, Q, R), where () is Dedekind's eta-function,and F(P, Q, R) is a polynomial in Ramanujan's Eisenstein seriesP, Q and R. We also derive identities in the case when d = 26.These lead to a new expression for ²⁶(). This work generalizesthe results for d = 1 and d = 3 which were given by Ramanujanon page 369 of ‘The Lost Notebook’.