Diversity And Distribution Of Pteriidae (Mollusca : Bivalvia) In Malaysian Waters [QL430.7.S915 C51 2007 f rb].

Kajian terhadap diversiti and taburan tiram Pteriidae di perairan Malaysia telah dilakukan di 9 lokasi yang merangkumi Selat Melaka (6 lokasi), Laut China Selatan (2 lokasi) dan Laut Sulawesi (1 lokasi). A study on the diversity and distribution of Pteriidae oysters in Malaysian waters has been conducted at 9 locations which covered the Straits of Malacca (6 locations), the South China Sea (2 locations) and the Sulawesi Sea (1 location)

Urea And Uric Acid Adsorption By Nanoporous Biomaterials

Kelemahan hemodialisis zaman ini telah menjadi punca penyelidikan dan pembangunan beberapa prototaip ginjal buatan mudah alih. Komponen utama model mudah alih ini (berbanding hemodialisis) ialah sistem dialisat tertutup. Secara tipikalnya, model-model ini biasanya menggunakan karbon teraktif sebagai bahan penjerap. Penggunaan bahan penjerap yang lebih unggul, jumlah dialisat yang diperlukan untuk penyingkiran toksin uremik boleh dikurangkan dan dikitar semula. Motivasi utama bagi penyelidikan ini ialah kekurangan pemilihan bahan untuk bahan penjerap dalam model-model ini. Oleh itu, objektif projek ini ialah sintesis dan penilaian tiga jenis biobahan berliang nano yang baru, iaitu gentian karbon teraktif berongga (ACF), silika berliang meso (MS) dan hidroksiapatit berliang meso, dengan sasaran untuk penyingkiran konstituen utama toksin uremik, iaitu urea dan asid urik. ACF telah diperolehi melalui kaedah pengaktifan asid dengan menggunakan asid-asid yang berbeza; asid bukan organic sulfurik, nitrik dan fosforik; asid organik asetik dan sitrik. MS dan HAp telah disintesis melalui kaedah templat lembut dengan surfaktan Pluronics. Keputusan awal penjerapan urea telah menunjukkan bahawa MS dengan kumpulan berfungsi amina dan ACF terawat asid sulfuric adalah sangat baik (550 mg/g) berbanding dengan karbon teraktif komersil (CAC). Ujian kinetik penjerapan urea telah mendedahkan mekanisma penjerapan urea oleh ACF (jerapan fizikal) dan MS (jerapan kimia). MS amina dan diamina menjerap lebih daripada 30 molekul per nm2 (jerapan kimia yang kuat) berbanding MS biasa, CAC dan pelbagai ACF, yang telah menjerap kurang daripada 10 molekul per nm2 (jerapan fizikal). Faktor-faktor utama yang mempengaruhi kapasiti jerapan ialah keliangan dan kimia permukaan yang sesuai, yang mana kedua-duanya dipunyai oleh MS amina dan diamina. Kebolehubahan permukaan berfungsi bagi MS merupakan asas untuk ujian jerapan urik asid seterusnya. Satu hipotesis peningkatan jerapan asid urik oleh MS terfungsi amina merupakan melalui tindak balas kimia asid-amina. Jerapan asid urik oleh MS tidak mengikut keluk jerapan teori. Analisa yang mendalam dengan menggunakan aplikasi MATLAB menunjukkan bahawa MS telah menjalani jerapan dan nyahrepan serentak, dengan kadar jerapan permulaan setinggi 20.3 mg/g/s berbanding gel silica dengan kadar jerapan hanya 0.39 mg/g/s. Sebagai kesimpulan, secara keseluruhannya, keputusan jerapan urea dan asid urik MS dan ACF lebih baik berbanding CAC dan gel silika komersil. ________________________________________________________________________________________________________________________ The limitations of the present hemodialysis have led towards the research and development of several wearable artificial kidney prototypes. The most important component of the miniaturised model is the closed-system dialysate, achieved through the utilisation of solid activated carbon as adsorbents. With the application of superior alternative adsorbents, the amount of dialysate required could be reduced due to efficient regeneration. The main motivation for this project is the lack of adsorbent materials selection. Thus, this project aims to synthesise and evaluate three emerging nanoporous biomaterials, i.e. hollow activated carbon fibre (ACF), mesoporous silica (MS) and mesoporous hydroxyapatite (HAp), targeting major uremic toxin constituent urea and uric acid. ACF was obtained though the acid activation route, with variation in acid used; inorganic acids sulphuric, nitric and phosphoric; organic acids acetic and citric. MS and HAp was synthesised through soft templating route using Pluronics surfactant. Results show that amine functionalised MS and sulphuric acid treated ACF performed well in the preliminary urea adsorption capacity evaluation (550 mg/g), as compared to the control commercial activated carbon (CAC) (350 mg/g). Subsequent urea kinetics study revealed better understanding of urea adsorption mechanism by ACF and MS, whereby ACF and MS operate through physisorption and chemisorption respectively. Amine and diamine MS adsorbed more than 30 molecules per nm2 (strong chemisorption interaction) compared to bare MS, CAC and various ACF, which adsorbed less than 10 molecules per nm2 (physisorption). The most important factors which govern adsorption capacity are porosity and suitable surface chemistry, both which are possessed by amine and diamine MS. The flexibility of surface functionalisation of MS is the basis of subsequent uric acid adsorption kinetics test. Amine functionalised MS is hypothesised to improve uric acid adsorption through acid-amine reaction. Uric acid adsorption by MS did not follow theoretical adsorption curve. Further analysis using MATLAB curve fit revealed that MS underwent simultaneous adsorption-desorption, with initial adsorption rates as high as 20.3 mg/g/s compared to commercial silica gel, with initial adsorption rate of 0.39 mg/g/s. As a conclusion, on a whole, MS and ACF performed better than the benchmarked CAC and commercial silica gel in terms of urea and uric acid adsorption

Unsteady Flow in Centrifugal Pump at Design and Off-Design Conditions

Ph.DDOCTOR OF PHILOSOPH

High particulate organic carbon export during the decline of a vast diatom bloom in the Atlantic sector of the Southern Ocean

Carbon fixation by phytoplankton plays a key role in the uptake of atmospheric CO2 in the Southern Ocean. Yet, it still remains unclear how efficiently the particulate organic carbon (POC) is exported and transferred from ocean surface waters to depth during phytoplankton blooms. In addition, little is known about the processes that control the flux attenuation within the upper twilight zone. Here, we present results of downward POC and particulate organic nitrogen fluxes during the decline of a vast diatom bloom in the Atlantic sector of the Southern Ocean in summer 2012. We used thorium-234 (234Th) as a particle tracer in combination with drifting sediment traps (ST). Their simultaneous use evidenced a sustained high export rate of 234Th at 100 m depth in the weeks prior to and during the sampling period. The entire study area, of approximately 8000 km2, showed similar vertical export fluxes in spite of the heterogeneity in phytoplankton standing stocks and productivity, indicating a decoupling between production and export. The POC fluxes at 100 m were high, averaging 26±15 mmol C m−2 d−1, although the strength of the biological pump was generally low. Only <20% of the daily primary production reached 100 m, presumably due to an active recycling of carbon and nutrients. Pigment analyses indicated that direct sinking of diatoms likely caused the high POC transfer efficiencies (~60%) observed between 100 and 300 m, although faecal pellets and transport of POC linked to zooplankton vertical migration might have also contributed to downward fluxes

Importance of deep mixing and silicic acid in regulating phytoplankton biomass and community in the iron-limited Antarctic Polar Front region in summer

En prens

The properties of slag-silica fume ternary blended mortar with quarry dust

High carbon emissions of manufactured Portland cement in the concrete industry have incurred several interests in reducing the use of Portland cement by partially replacing it with supplementary cementitious materials. Most of which, are by-products from other manufacturing industries. Hence, the main purpose of this study is to investigate the effects of different combinations of ternary blended mortars incorporating supplementary cementitious materials such as Ground Granulated Blast Furnace Slag (GGBS) and Densified Silica Fume (DSF). In this study, mortars were prepared with 100% quarry dust and GGBS was replaced with DSF at 2% step increments up to 16% at a w/b ratio of 0.24. At the same time OPC content was fixed at 50%. The compressive and flexural strength, drying shrinkage, and porosity of mortars were all tested. The results indicated that the increasing DSF content increases; GGBS reduces the superplasticizer dosage for the desired workability of the mortar. The utilization GGBS and DSF has improved the performances ternary blended mortar incorporating quarry dust as a fine aggregate in terms of mechanical strength, drying shrinkage and total porosity tested. The high strength ternary blended mortar incorporating GGBS and DSF exhibited optimum mechanical and durability performance at the OPC:GGBS:DSF ratio of 50:38:12

Controls of primary production in two phytoplankton blooms in the Antarctic Circumpolar Current

Versión del edito

Oxygenated volatile organic carbon in the western Pacific convective center : ocean cycling, air–sea gas exchange and atmospheric transport

© The Author(s), 2017. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Atmospheric Chemistry and Physics 17 (2017): 10837–10854, doi:10.5194/acp-17-10837-2017.A suite of oxygenated volatile organic compounds (OVOCs – acetaldehyde, acetone, propanal, butanal and butanone) were measured concurrently in the surface water and atmosphere of the South China Sea and Sulu Sea in November 2011. A strong correlation was observed between all OVOC concentrations in the surface seawater along the entire cruise track, except for acetaldehyde, suggesting similar sources and sinks in the surface ocean. Additionally, several phytoplankton groups, such as haptophytes or pelagophytes, were also correlated to all OVOCs, indicating that phytoplankton may be an important source of marine OVOCs in the South China and Sulu seas. Humic- and protein-like fluorescent dissolved organic matter (FDOM) components seemed to be additional precursors for butanone and acetaldehyde. The measurement-inferred OVOC fluxes generally showed an uptake of atmospheric OVOCs by the ocean for all gases, except for butanal. A few important exceptions were found along the Borneo coast, where OVOC fluxes from the ocean to the atmosphere were inferred. The atmospheric OVOC mixing ratios over the northern coast of Borneo were relatively high compared with literature values, suggesting that this coastal region is a local hotspot for atmospheric OVOCs. The calculated amount of OVOCs entrained into the ocean seemed to be an important source of OVOCs to the surface ocean. When the fluxes were out of the ocean, marine OVOCs were found to be enough to control the locally measured OVOC distribution in the atmosphere. Based on our model calculations, at least 0.4 ppb of marine-derived acetone and butanone can reach the upper troposphere, where they may have an important influence on hydrogen oxide radical formation over the western Pacific Ocean.This work was supported by the EU project SHIVA under grant agreement no. FP7-ENV- 2007-1-226224 and by the BMBF grants SHIVA-Sonne (FKZ: 03G0218A). Astrid Bracher and Wee Cheah were funded via the HGF Young Investigator Group PHYTOOPTICS (VH-NG-300) from the Helmholtz Association through the President. Astrid Bracher’s contribution was also partly funded by ESRIN/ESA within the SEOM (Scientific Exploration of operational missions) – Sentinel for Science Synergy (SY-4Sci Synergy) program via the project SynSenPFT. Additional funding for Cathleen Schlundt, Christa A. Marandino and Sinikka T. Lennartz came from the Helmholtz Young Investigator Group of Christa A. Marandino, TRASE-EC (VH-NG-819), from the Helmholtz Association through the President’s Initiative and Networking Fund and the GEOMAR Helmholtz-Zentrum für Ozeanforschung Kiel