Rice husk, an agricultural waste from the rice industry, can cause serious environmental pollution if not properly managed. However, rice husk ash (RHA) has been found to have many positive properties, making it a potential replacement for non-renewable peat in soilless planting. Thus, this study investigated the impact of a RHA composite substrate on the growth, photosynthetic parameters, and fruit quality of cucumber (Yuyi longxiang variety) and melon (Yutian yangjiaomi variety). The RHA, peat, vermiculite, and perlite were blended in varying proportions, with the conventional seedling substrate (peat:vermiculite:perlite = 1:1:1 volume ratio) serving as the control (CK). All plants were cultivated in barrels filled with 10L of the mixed substrates. The results from this study found that RHA 40 (RHA:peat:vermiculite:perlite = 4:4:1:1 volume ratio) significantly enhanced substrate ventilation and positively influenced the stem diameter, root activity, seedling index, chlorophyll content, net photosynthetic rate (Pn), stomatal conductance (Gs), and transpiration rate (Tr) of cucumber and melon plants. Additionally, plant planted using RHA 40, the individual fruit weight of cucumber and melon found to increase by 34.62% and 21.67%, respectively, as compared to the control. Aside from that, both cucumber and melon fruits had significantly higher sucrose, total soluble sugar, vitamin C, and soluble protein levels. This subsequently improved the activity of sucrose synthase and sucrose phosphate synthase in both cucumber and melon. In conclusion, the RHA 40 found to best promote cucumber and melon plant growth, increase plant leaf photosynthesis, and improve cucumber and melon fruit quality, making it a suitable substrate formula for cucumber and melon cultivation in place of peat.
This study marks the first-ever assessment of radiological hazards linked to the sands and rocks of Patuartek Sea Beach, situated along one of the world's longest sea beaches in Cox' Bazar of Bangladesh. Through the utilization of an HPGe detector, a comprehensive analysis of the activity concentrations of 226Ra, 232Th, and 40 K was conducted, and their activity ranged from 7 to 23 Bq/kg, 9-58 Bq/kg, and 172-340 Bq/kg, respectively, in soils, and 19-24 Bq/kg, 27-39 Bq/kg, and 340-410 Bq/kg, respectively, in rocks. Some sand samples exhibited elevated levels of 232Th, while the rock samples displayed higher levels of 40 K compared to the global average. The radiological hazard parameters were assessed, and no values surpassed the recommended limits set by several international organizations. Hence, the sands and rocks of Patuartek sea beach pose no significant radiological risk to the residents or tourists. The findings of this study provide crucial insights for the development of a radiological baseline map in the country, which is important due to the commissioning of the country's first nuclear power plant Rooppur Nuclear Power Plant. The data may also stimulate interest in the rare-earth minerals present in the area, which is important for the electronics industry, thorium-based nuclear fuel cycles.
This research investigates the strength of kenaf or epoxy composite filled with mesoporous silica and
studies the hybrid effects between mesoporous silica or kenaf in epoxy matrix. The volume of kenaf
woven mat is maintained constantly at 7.2vol%, whereas proportion of epoxy is varied with inclusion of
mesoporous silica and silicon, keeping constant the volume of the composite at 67.5cm3. The proportion
of mesoporous silica is altered from 0.5vol%, 1.0vol%, 3.0vol% and 5.0vol%, while silicon is kept
constant at 3.0vol%. A total of 11 specimens were produced, each with its distinctive composition and
mechanical strengths. Variation of fillers composition affects the mechanical strengths of the composite.
SEM analysis shows that epoxy bonds well with silicon, kenaf and mesoporous silica. Some de-bonding
among the components is observed within the composite although there is also some tearing of fibres and
impregnation of epoxy within fibre, proving that the components have good interaction and do not act
individually. Flexural test shows that mesoporous silica improves the flexural strength of the composite,
where the highest value is 35.14MPa, obtained at 5.0vol% Mesoporous Silica in Kenaf/Epoxy (SiaK/
Ep). It also improves the flexural modulus, where the highest value is 1569.48MPa, obtained at 3.0vol%
SiaK/Ep. DMA result reveals that adding mesoporous silica increases the Tg of the composite produced.
Highest Tg is obtained at 0.5vol% Mesoporous Silica in Kenaf/Epoxy modofied Silicon (SiaK/Ep-Si)
with the value of 87.54°C.
Silicon dioxide (SiO2) has been extensively studied due to their unique properties that make it desirable for many applications ranging from electronic, catalysis, pigment as well as sensors. Multitude of methods and processes are established with the ability to manipulate and control the key properties that can cater for specific applications. Stober method is a very simple and easy for up-scale production of SiO2. This paper presents the experimental study on the effect of synthesis parameter on the morphology of SiO2 synthesized via Stober method. Three parameters were investigated such as concentration of catalyst, concentration of precursor and percentage of water content. The obtained samples were characterized using scanning electron microscopy (SEM) analysis. The findings showed that the size of particles produced is dependent on the synthesis parameter. In this study, particles size ranging from 50 nm to >100 nm are easily produced. The sphere size of SiO2 can be increased by increasing the concentration of ammonia hydroxide catalyst, the concentration of TEOS, as well as the percentage of water content.
The Kodiang Formation which outcrops in Kodiang and Alor Setar areas has been well studied and documented. Various geological aspects of the limestone formation have been reported in detail including its stratigraphy, sequence startigraphy, sedimentology and paleontology. Diagenetic aspect of this rock formation, however, had not been specifically discussed before. The Kodiang limestone has undergone a complicated diagenetic history which started immediately after the sediments were laid down on the sea bed. Various diagenetic products have been identified including, early marine cement, meteoric cement, and deeper subsurface cement. The diagenetic features identified are as follows; Fibrous calcite cement, sparry and poikilotopic calcites, calcite overgrowth, dolomite, silica cements and evaporites. Close examination at outcrops shows that dolomite occurs at several levels in the sequence. Their systematic occurrences can be correlated across the area. Petrographic studies show that dolomite occurs in several modes as stratified dolomite and as non-stratified dolomite. The two dolomite groups are attributed to two phases of dolomitizations. The stratified dolomites are interpreted to have been formed early in the limestone diagenetic history. The non-stratified dolomite type is, however, attributed to dolomitization during deep burial under the control of deeper subsurface physico-chemical conditions.
Batu Kapur Kodiang yang tersingkap di Kodiang dan Alor Setar telah banyak dikaji dan didokumentasikan. Berbagai aspek geologi formasi batu kapur ini telah dilaporkan termasuk stratigrafi, startigrafi jujukan, sedimentologi dan paleontologi. Walau bagaimanapun aspek diagenesis formasi batuan ini tidak pernah dibincangkan secara khusus. Batu kapur Kodiang ini telah melalui sejarah diagenesis yang rumit yang bermula sebaik saja sedimen dimendapkan di atas permukaan dasar laut. Berbagai hasil diagenesis telah dikenal pasti termasuk penyimenan samudera awal, penyimenan meterorik dan penyimenan di bawah permukaan yang lebih dalam. Secara asas fitur-fitur yang dikenalpasti adalah seperti berikut; simen kalsit berserat, kalsit spar dan poikilotopik, tumbuhlampau kalsit, dolomit, simen silika dan evaporit. Pemeriksaan rapi pada singkapan menunjukkan dolomit hadir pada beberapa aras di dalam jujukan. Kehadirannya secara bersistematik boleh dikorelasikan pada setiap singkapan. Kajian petrografi menunjukkan dolomit wujud dalam berbagai mod yang boleh diklaskan sebagai dolomit berstrata dan dolomit tidak berstrata. Dua klas ini boleh dikaitkan dengan dua fasa pendolomitan. Dolomit berstrata ditafsirkan telah terbentuk awal di dalam sejarah diagenesis batu kapur. Dolomit tidak berstrata pula dikaitkan dengan pendolomitan semasa timbusan dalam di bawah keadaan fiziko-kimia bawah permukaan.
A study of the major Arthropoda taxa of invertebrates recolonizing Saraca roots occurring on various substrates and under various water velocities was carried out in the upper reaches of the Gombak River. The sites for the recolonization experiments were selected in the fast and slow flowing sections of rocks and boulders, sand and gravel and mud and silt biotopes. The Hydropsychidae and the Nemouridae were the pioneer recolonizers of Saraea roots in the fast flowing sections of the stream whereas the Ptilodactylidae and the Caenidae were the pioneer recolonizers in the slow flowing sections of the stream.
Suatu kajian telah dijalankan bagi menentukan takson utama invertebrata Arthropoda yang mengkoloni semula akar Saraca yang didapati pada pelbagai substrat dan pada kelajuan air yang berbeza di bahagian hulu Sungai Gombak. Tapak-tapak untuk ujikaji pengkolonian-semula telah dipilih pada bahagian laju dan perlahan biotop batuan besar dan sederhana, pasir dan batuan kecil, dan lumpur dan kelodak. Hydropsychidae dan Nemouridae adalah pengkoloni perintis pada akar Saraca di bahagian aliran laju sungai sementara Ptilodactylidae dan Caeflidae adalah pengkoloni perintis di bahagian aliran perlahan sungai itu.
In this study TiO2 films have been prepared using two different techniques i.e. sol-gel and electron gun evaporation (e-gun) techniques. The films were annealed at 300, 350 and 400oC in air. The microstructure study using field emission scanning electron microscope and x-ray diffractometer showed nanometer grains size and only the film prepared by sol-gel and annealed at 400oC has anatase phase while others are amorphous. To study the effect of the films (as buffer layer) onto the dielectric bolometer Ba0.6Sr 0.4TiO3 as distance sensor, sensors with the configuration of Al/BST/TiO2/RuO2/SiO2/Si were built. Two different measurements i.e. with and without infrared source were carried out to measure the sensitivity and repeatability of the sensors. The sensors which contained sol-gel TiO2 films gave reading for both type of measurements, indicating that the sensor can act as active and passive sensors. However, the sensors which contained e-gun TiO2 films only gave responses when the IR source was used, indicating that they can only act as passive sensors. The most sensitive sensor was TiO2 film prepared by sol gel and annealed at 350oC. In general sensors which contained TiO2 films prepared by sol gel showed good repeatability.
Bottom-contact pentacene OTFTs are fabricated using cross-linked poly(vinyl alcohol) (PVA) insulator and its reliability characteristics are analyzed. The hysteresis of the OTFTs is mainly caused by the electrons that are injected from the gate electrode to the cross-linked PVA insulator. To block the injection of electrons, plasma-enhanced chemical vapor deposition (PECVD) SiO2 layer is inserted between the gate electrode and the cross-linked PVA layer, so that the minimum hysteresis can be obtained. In addition, the effects of the gate bias stress as a function of time is investigated to examine the long-term reliability of the device during the operation.
Thin films of barium strontium titanate (Ba0.6Sr0.4TiO3) perovskite system are promising candidates for microelectronic devices that can be integrated with semiconductor technology. Ba0.6Sr0.4TiO3 thin films have been prepared onto BST/TiO2/RuO2/SiO2/Si substrate using the spin coating and sol-gel process. Then the samples were subsequently annealed at 600oC, 650oC and 700oC for 60 minutes in air. The microstructure and dielectric properties show that the crystallization improved as the annealing temperature was increased. All of the films have nanometer grain size. The average grain size of the films increased as the temperature was increased. The dielectric constant and ac conductivity of the films also increased as the average grain size increased. These results showed that the microstructure and dielectric properties depend on the annealing temperature.
Spatial and temporal variations in silica concentration were determined at various rivers and tributaries in the Linggi River Basin, which has been highly polluted due to urban, industrial and agricultural wastes. The silica content measured as reactive silicate in the whole Linggi River Basin ranged from 1.4 to 26.3 mg/L. A clear seasonal variation in silica was noted especially in the major rivers with higher concentration during dry months and lower concentration during the wet months. The concentration was found to decrease as the water flooded downstream. The large drainage area with granite dominated lithology and high denudation especially in the upper catchment is attributed for high silica content in the water of Linggi River Basin.
Infiltration caused by rainfall will lead to the changes of moisture content and soil pore water pressure or matric suction of the soil. These changes indicate the behavior of the soil especially during wetting and drying process. This paper presents the experimental test result of rain water infiltration into soil column for two samples of soils. The main objectives were to study the effect of rainfall intensity and duration of soil infiltration process for the forest soil and to compare its result to the gravelly sand. Infiltration experimental in this study involved three main components; water supply system, soil column and instrumentations, including percolation collection system. This study uses two types of tensiometers; 5 and 10 cm long. The results of TDR and tensiometers which were used to obtained moisture content and matric suction, respectively, shows that the system was successfully developed. For the forest soil, the result showed that moisture content of the top section is higher compared with the other sections. On the other hand, for gravelly sand, the moisture content in middle section is higher compared with the top and bottom section of the soil. Meanwhile, matric suction for both soils dropped during rainfall and gradually increases towards drying process. Other than that the comparison of soil matric suction between 5 and 10 cm tensiometers shows significant results for gravelly sand compared to forest soil.
Dry sliding wear of polyester hybrid composites containing carboxylic functionalized multi-walled carbon nanotubes (cNT) and microparticles, silica (Si02) was studied at different sliding distances. An attempt has been made to produce uniform dispersion of nano- and micro- particles in the test samples by ultrasonication. The tribological properties of the hybrid composites were performed by using pin-on-disc (POD) tester against grey cast iron countersurface. The dry sliding wear tests were carried out under pressure-velocity (pv) condition of 0.4 MPa and 4 m/s for total sliding distance of 28800 m and at an interval of every sliding distance of 3600 m, wear properties and behavior were studied. The samples containing 10 wt.% silica (microparticles) with and without CNT always show increase in coefficient of friction at the expense of wear rate. However, samples containing only ci'rr have the lowest wear rate with the increase in coefficient of friction. Sliding distance studies also provide the information on wear rates which were ever changing at different sliding distances whereas average coefficient of friction did not vary throughout the tests. SEM observations of wear surfaces showed different wear morphologies when reinforcement (cNT or Si02) incorporated into the composites either alone or in combination.
The mechanical properties of fractured rock mass are largely dependent on the fracture structure under the coupling of freeze-thaw cycles and large temperature difference. Based on the traditional macroscopic continuum theory, the thermal and mechanical model and the corresponding theories ignore the material internal structure characteristics, which add difficulty in describing the mesoscopic thermal and mechanical behavior of the fractured rock mass among different phases. In order to uncover the inherent relationship and laws among the internal crack development, structural change and the physical and mechanical properties of rock under strong cold and frost weathering in cold area, typical granite and sandstone in cold region were analyzed in laboratory tests. The SEM scanning technology was introduced to record the microstructural change of rock samples subject to freeze-thaw cycles and large temperature difference. Association rules between the microstructure and the physical mechanical properties of rock mass were analyzed. The results indicated that, with the increase of the cyclic number, the macroscopic physical and mechanical indexes and the microscopic fracture index of granite and sandstone continuously and gradually deteriorate. The width of original micro crack continues to expand and extend and new local micro cracks are generated and continue to expand. The fracture area and width of the rock increase and the strength of the rock is continuously damaged. In particular, the strength and elastic modulus of granite decrease by 20.2% and 33.36%, respectively; the strength and elastic modulus of sandstone decrease by 33.4% and 36.43%, respectively.
Siliceous mesoporous molecular sieve (Si-MCM-41) material with highly ordered hexagonal pore arrangement was synthesized at 373 K for 8-days duration by hydrothermal method, dried at 393 K and calcined at 823 K in N2 atmosphere. The calcined Si-MCM-41 was later functionalized with 10-50 wt. % monoethanolamine (MEA) by impregnation method and dried in vacuum at 343 K. The MEA-Si-MCM-41 samples were characterized for their physicochemical properties with FTIR, XRD, TGA, HRTEM, FESEM, BET and elemental analysis. XRD results showed that the intensity of the characteristic peaks of Si-MCM-41 reduces with increasing loading of MEA indicating that the MEA molecules are loaded in the pores as well as on the surface of Si-MCM-41. The appearance of FTIR peaks corresponding to N-H, C-N and C-H bonds suggested that Si-MCM-41 has been functionalized with MEA. The presence of Si-O-Si peaks in FTIR spectra of MEA-Si-MCM-41 samples indicates that the hexagonal pore arrangement remains intact and this is supported by HRTEM images. FESEM images show that MEA-Si-MCM-41 samples became agglomerated with increase loading of MEA. TGA analyses show that the MEA-Si-MCM-41 samples are thermally stable up to 528 K. N2 adsorption-desorption isotherms show that the textural properties of Si-MCM-41 material slowly change from a mesoporous material to non-porous material as the MEA loading increases due to pore filling effect during functionalization with MEA. Detection of N, C and H by elemental analysis confirms the presence of MEA in MEA-Si-MCM-41 samples.
This paper describes the preparation, characterisation, and potential application of flexible palm oil-based polyurethane foam (PUF) as a support for iron-silica (Fe-Si) adsorbent. Fe-Si/polyurethane composite (Fe-Si/PUC) was prepared by impregnating Fe-Si adsorbent onto the surface of PUF by using a novel immersion-drying method. Morphological analysis of Fe-Si/PUC proved that Fe-Si was successfully impregnated onto the surface of PUF. Compression test and thermogravimetric analysis were carried out to determine the flexibility and thermal stability of Fe-Si/PUC, respectively. The Fe-Si/PUC removed 90.0% of 10 ppm methylene blue (MB) from aqueous solution in 60 min. The reusability study showed that Fe-Si/PUC removed 55.9% of MB on the seventh cycle. Hence, the synthesis of Fe-Si/PUC opens up a new path of implementing palm oil-based PUF to assist in the recovery of an adsorbent for environmental clean-up. The mechanism of physical interaction during the impregnation of Fe-Si adsorbent onto PUF was proposed in this paper.
This study was conducted to determine the influence of the oil palm boiler ash (OPBA) reinforcement on the microstructural, physical, mechanical and thermal properties of epoxy polymer composites. The chemical composition analysis of OPBA revealed that it contains about 55 wt.% of SiO2 along with other metallic oxides and elements. The surface morphology of OPBA showed angular and irregular shapes with porous structures. The influence of OPBA as a reinforcement in epoxy composite was studied with varying filler loadings (10-50 wt.%) and different particle sizes (50-150 μm). The result showed that the incorporation of OPBA in composites has improved the physical, mechanical and thermal properties of the epoxy matrix. The highest physical and mechanical properties of fabricated composites were attained with 30 wt.% loading and size of 50 μm. Also, thermal stability and the percentage of char residue of the composite increased with increasing filler loading. Furthermore, the contact angle of OPBA reinforced epoxy composites increased with the increase of filler loading. The lowest value of the contact angle was obtained at 30 wt.% of filler loading with the OPBA particle size of 50 μm. The finding of this study reveals that the OPBA has the potential to be used as reinforcement or filler as well as an alternative of silica-based inorganic fillers used in the enhancement of mechanical, physical and thermal properties of the epoxy polymer composite.
The dispersion of hyperaccumulators used in the phytoremediation process has caused environmental concerns because of their heavy metal (HM) richness. It is important to reduce the environmental risks and prevent the HM to reenter the ecological cycle and thereby the human food web. In this work, supercritical water gasification (SCWG) technology was used to convert Sedum plumbizincicola into hydrogen (H2) gas and to immobilize HMs into biochar. The H2 production correlated with temperature ranging from 380 to 440 ℃ with the highest H2 yield of 2.74 mol/kg at 440 ℃. The free-radical reaction and steam reforming reaction at high temperatures were likely to be the mechanism behind the H2 production. The analyses of bio-oil by the Gas Chromatography-Mass Spectrometer (GC-MS) and Nuclear magnetic resonance spectroscopy (NMR) illustrated that the aromatic compounds, oxygenated compounds, and phenols were degraded into H2-rich gases. The increase of temperature enhanced the HM immobilization efficiency (>99.2 % immobilization), which was probably due to the quickly formed biochar that helped adsorb HMs. Then those HMs were chemically converted into stable forms through complexation with inorganic components on biochar, e.g., silicates, SiO2, and Al2O3. Consequently, the SCWG process was demonstrated as a promising approach for dispersing hyperaccumulators by immobilizing the hazardous HMs into biochar and simultaneously producing value-added H2-rich gases.
Fast and efficient separation remains a big challenge in high performance liquid chromatography (HPLC). The need for higher efficiency and resolution in separation is constantly in demand. To achieve that, columns developed are rapidly moving towards having smaller particle sizes and internal diameters (i.d.). However, these parameters will lead to high back-pressure in the system and will burden the pumps of the HPLC instrument. To address this limitation, monolithic columns, especially silica-based monolithic columns have been introduced. These columns are being widely investigated for fast and efficient separation of a wide range of molecules. The present article describes the current methods developed to enhance the column efficiency of particle packed columns and how silica monolithic columns can act as an alternative in overcoming the low permeability of particle packed columns. The fundamental processes behind the fabrication of the monolith including the starting materials and the silica sol-gel process will be discussed. Different monolith derivatization and end-capping processes will be further elaborated and followed by highlights of the performance such monolithic columns in key applications in different fields with various types of matrices.
Glass ionomer cement (GIC) has theunique fluoride release property and able to formionic bond with tooth structure. However, the brittleness of the material results in low hardness. In the present study, a new approach in utilization of local waste materials as fillers for improvement of hardness of GIC is reported.The synthesized wollastonite and mine-silica by-product were individually incorporated into commercial GIC and the Vickers hardness were evaluated. The results shown that the incorporation of 1 % wollastonite into GIC gave ~ 6% increment in hardness compared to the control GIC (66.53H ±7.37 versus 62.66HV±2.98)but not for themine-silica. Thus, wollastonite could be a potential material to be utilized as fillersin dental restorative composite
Compartmented Fluidized Bed Gasifier (CFBG), consisting of two compartments - the combustorand gasifier, uses air blown instead of pure oxygen for syngas production in bubbling fluidization mode, eliminating the need of air separation unit, and reducing the capital cost, thus distinguishes it from other traditional ones. Fluidization quality is a determining factor in the CFBG to guarantee its well-lifted behaviour. Previous study, without solid circulation at ambient conditions, brought to the fore the necessity of considering the effect of the minimum allowable effective diameter. The study was then performed in the CFBG cold physical model of 0.66m overall diameter (effective diameter for combustor and gasifier is 0.413m and 0.257m) to investigate the fluidization quality and compare it with the results obtained from the previous cold model of about 1.36 times smaller, but with the same compartmented ratio of 65:35. Different inert particles (river sand, quartz sand and alumina) were used, over a range of aspect ratios, for the aforementioned objective. The results showed that the fluidization quality in the gasifier has not been achieved and the degradation of fluidization quality in the combustor is still observed, notwithstanding the fact that the condition of the minimum allowable effective diameter has been met. The reduction of distributor free area, to increase the distributor pressure drop, showed a marginal effect on the quality. The effect of the minimum allowable effective diameter on fluidization quality in CFBG as well as the interplay of geometric and operational parameters require further studies be carried out. The fluidization quality of the binary mixture is also currently under investigation.