A process to produce calcium phosphate biomaterial was done using an organic based diethylhexyl phosphoric acid (DEHPA) as its starting material. The gel obtained from this reaction was used to study calcium phosphate transformation using in-situ XRD with temperature ranges from room temperature to 1300 o C. The results obtained from this analysis show the following phase transformation sequence gel > β-Ca2P2O7 > β-TCP + HA > α-TCP + HA. β-Ca2P2O7 was formed at 400 o C and the sample when heated up to 1000 o C, peaks of β- TCP and HA appeared showing the transformation of the β-Ca2P2O7 phase. When the sample was heated up further to 1200 o C, β-TCP transformed into α-TCP.
Two new species, Phlegmariurus iminii Kiew (Lycopodiaceae) from limestone karst and P. monticola Kiew from montane habitats, are described from Peninsular Malaysia and a new combination is made for Phlegmariurus pinifolius (Trevis.) Kiew. Phlegmariurus iminii, known from a single hill threatened by quarrying, is Critically Endangered; while P. monticola and P. pinifolius that are relatively widespread are of Least Concern.
Bandgap tuning of a mixed organic cation perovskite is demonstrated via chemical vapor deposition process. The optical and electrical properties of the mixed organic cation perovskite can be manipulated by varying the growth time. A slight shift of the absorption band to shorter wavelengths is demonstrated with increasing growth time, which results in the increment of the current density. Hence, based on the optimized growth time, our device exhibits an efficiency of 15.86% with negligible current hysteresis.
Cellulose nanocrystals, a class of fascinating bio-based nanoscale materials, have received a tremendous amount of interest both in industry and academia owing to its unique structural features and impressive physicochemical properties such as biocompatibility, biodegradability, renewability, low density, adaptable surface chemistry, optical transparency, and improved mechanical properties. This nanomaterial is a promising candidate for applications in fields such as biomedical, pharmaceuticals, electronics, barrier films, nanocomposites, membranes, supercapacitors, etc. New resources, new extraction procedures, and new treatments are currently under development to satisfy the increasing demand of manufacturing new types of cellulose nanocrystals-based materials on an industrial scale. Therefore, this review addresses the recent progress in the production methodologies of cellulose nanocrystals, covering principal cellulose resources and the main processes used for its isolation. A critical and analytical examination of the shortcomings of various approaches employed so far is made. Additionally, structural organization of cellulose and nomenclature of cellulose nanomaterials have also been discussed for beginners in this field.
Precipitated calcium carbonate fillers were loaded into the lumen of bleached mixed tropical hardwood pulp using polyethylenimine (PEI) and alum. Our results indicated that the addition of (PEI) increased the degree of loading of precipitated calcium carbonate (PCC) into the lumen of fibers. The degree of loading also increased with the addition of alum together with PEI. The mechanical strengths of the produced lumen loaded paper increased with the addition of PEI and alum. Meanwhile the mechanical strength without alum had slightly increased the mechanical strengths of the paper. Electron micrographs revealed that the PCC fillers were successfully loaded into the lumen of the fibers.
Miocene larger benthic foraminifera have been discovered from a limestone unit of the Kalumpang Formation. The limestone is exposed at the Teck Guan Quarry, Tawau, southeast Sabah. The Kalumpang Formation consists predominantly of interbedded mudstone and sandstone (graywacke), conglomerate, limestone, marl, chert and volcanic rocks. Five limestone samples have been collected and processed for petrographic analysis and identification of larger benthic foraminifera. The limestone is classified as packstone and mudstone. A total of seventeen species of larger benthic foraminifera have been identified. The foraminifera are divided into two assemblages namely Assemblage I and Assemblage II. Assemblage I is characterized by the presence of Lepidocyclina (Nephrolepidina) parva, Operculina sp. and Lepidocyclina (Eulepidina) formosa. This assemblage is an indicative of Aquitanian to Burdigalian in age (Early Miocene). Assembalge II comprises of Lepidocyclina (Nephrolepidina) sumatrensis, Lepidocyclina (Nephrolepidina) angulosa, Lepidocyclina (Nephrolepidina) ferreroi Lepidocyclina sp., Miogypsina sp., Katacycloclypeus annulatus, Katacyloclypeus martini, Cycloclypeus carpenteri, Cycloclypeus indopacificus, Cycloclypeus sp., Flosculinella bontangensis, Operculina complanata, Amphistegina bowdenensis and Amphistegina sp. This assemblage is an indicative of Langhian to Serravallian age (Middle Miocene). The foraminiferal assemblages suggest that the depositional environment was a warm tropical shallow-marine at the fore-reef shelf zone.
The Semantan Formation which is Middle to Upper Triassic age, comprises a rapidly alternating sequence of carbonaceous shale, siltstone and rhyolite tuff with a few lenses of chert, conglomerate and recrystallised limestone. The shale and tuff make up the bulk of the sequence. Jaafar Ahmad (1976) was introduced the formation name of the rock sequence in Karak-Temerloh area, but the similar sequence (in term of lithology, paleontology and structural pattern) found in the other areas were given different names. After an extensive study, the following formations or part of them, may be include in the Semantan Formation; Raub Series (Scrivenor 1911); Calcareous Formation (Richardson 1939); Calcareous Series (Richardson 1947); Younger arenaceous Series (Alexander 1956); Raub Group (Alexander 1959); Jengka Pass Formation (Ichikawa et al. 1966); Kerdau Formation (Burton 1973a); part of Jelai Formation (Burton 1973a); Gemas Formation (Lum 1977); Jurong Formation (Burton 1973a); Pahang Volcanic Series (Hutchison 1973c).
Formasi Semantan merupakan jujukan batuan sedimen yang berusia Trias Tengah - Akhir di Jalur Tengah Semenanjung Malaysia. Jujukan ini terdiri daripada selang lapis batuan syal berkarbon, batu lodak, dan batu pasir yang kebanyakannya bertuf, serta terdapat kekanta konglomerat, batu kapur dan rijang dalam selang lapis ini. Syal adalah unit yang paling dominan dalam formasi ini. Jaafar Ahmad (1976) menamakan jujukan ini untuk kawasan Karak - Temerloh, tetapi jujukan yang serupa (dari segi litologi, paleontologi dan gaya struktur) juga ditemui di kawasan lain, tetapi dipanggil dengan nama lain. Dari hasil kajian menyeluruh yang telah dijalankan, didapati nama-nama unit batuan berikut atau sebahagian daripadanya mungkin merupakan penamaan yang serupa untuk Formasi Semantan, iaitu Siri Raub (Scrivenor 1911), Formasi Berkapur (Richardson 1939), Siri Berkapur (Richardson 1947), Siri Arenit Muda (Alexander 1958), sebahagian Kumpulan Raub (Alexander 1959), Formasi Jengka Pass (Ichikawa et al. 1966), Formasi Kerdau (Burton 1973a), sebahagian Formasi Jelai (Burton 1973a), Formasi Gemas (Lum 1977), Formasi Jurong (Burton 1973a) dan Siri Volkano Pahang (Hutchison 1973).
To evaluate the correlation of the intragranular textures on the physical properties of coarse aggregates, four aggregates samples consisting of three granitoid sources and one limestone have been studied. The role played by intragranular textures (mineral assembladge, grain size and grain boundaries) in influencing the physical properties are potentially significant to the fact that such textural variation may complicate the aggregate strength. This study indicates that the aggregates exhibited variation in textural habits. The granitoid aggregates, which is rich with silicate composition has typical heterogranular textures of porphyritic and equigranular grain structures. Whereas the limestone aggregate comprises of bioclast and peloid allochems cemented by micrite and spar. The granitoid aggregates showed better dispersed characters and had extremely interlocking crystal boundaries which have more physical strength compared to a carbonate aggregate.
Addition of chemical binders such as lime and cement improves the strength and stiffness
of fine grained soils. However, the treated soils exhibit brittle stress-strain behaviour.
Inclusion of randomly oriented discrete fibers in the soil-binder mixture changes its brittle
behaviour into ductile behaviour. Most synthetic fibers, however, tend to get entangled
and cannot be easily separated from one another. Therefore, it is difficult to realize soilbinder-
fiber mixtures in which the fibers are distributed uniformly throughout the mass.
This issue has been an impediment in the utilization of the positive modification in the
behaviours of soils and soil-binder mixtures by the fibers. The present study aims to address
the limitations in using fibers as soil reinforcement. Further, it also aims to investigate
the use of synthetic mesh or net elements as an alternative type of soil reinforcement.
The paper presents the experimental study on a fine grained soil. Lime has been chosen
as the binder due to its low cost and the scarcity of fiber reinforced soil studies in which
lime has been used as a binder. The main experimental program is a series of unconfined
compression tests on samples prepared using untreated soil, soil-reinforcement mixture,
soil-lime mixture, and soil-lime-reinforcement mixture. The lime treated samples were
cured up to 120 days at laboratory temperature. The results demonstrate the combinational
effects of lime and discrete reinforcement
elements on the behaviour and mechanical
properties of the soil. The performances of
the fiber and mesh element reinforcements
have also been compared.
In this report we have evaluated radiation effective dose received by patients during ECG-gated CCTA examinations based on gender, heart rate, tube voltage protocol and body mass index (BMI). A total of 1,824 patients were retrospectively recruited (1,139 men and 685 women) and they were divided into Group 1 (CCTA with calcium scoring), Group 2 (CCTA without calcium scoring) and Group 3 (only calcium scoring), where the association between gender, heart rate, tube voltage protocol and body mass index (BMI) were analysed. Examinations were performed using a retrospective ECG-gated CCTA protocol and the effective doses were calculated from the dose length product with a conversion coefficient of 0.026 mSv.mGy-1cm-1. No significant differences were observed in the mean effective dose between gender in all groups. The mean estimated dose was significantly higher when the heart rate was lower in Group 1 (p
The stability of the limestone cliff at Gunung Kandu, Gopeng, Perak, Malaysia was assessed based on the Slope Mass
Rating (SMR) system on 53 cross sections of the Gunung Kandu hill slopes. The slopes of Gunung Kandu were identified
as class I (very good) to IV (poor). The kinematic analysis showed that 12 out of 53 hill slopes of Gunung Kandu were
identified as having potential wedge, planar and toppling failures. The assessment showed that the stability of the western
flanks can be classified as stable to unstable with the probability of failure from 0.2 to 0.6. The stability of the eastern and
southern flanks range from very stable to partially stable with the probability of failure from 0.0 to 0.4. While the stability
of northern flanks are from very stable to stable with the probability of failure of 0.0 - 0.2. This systematic approach
offers a practical method especially for large area of rock slope stability assessment and the results from probability of
failure values will help engineers to design adequate mitigation measures.
Present research concerns the TL signal stored in chalk of the variety commercially available for writing on blackboards. Samples of this have been subjected to x-ray irradiation, the key dosimetric parameters investigated including dose and energy response, sensitivity, fading and glow curve analysis. Three types of chalk have been investigated, each in five different colours. The samples were annealed at 323 K prior to irradiation. For all three chalk types and all five colours, the dose response has been found linear over the investigated dose range, 0-9 Gy. Regardless of type or colour, photoelectric energy dependency is apparent at the low energy end down to the lowest investigated accelerating potential of 30 kV. Crayola (Yellow) has shown the greatest TL sensitivity, thus selection has been made to limit further analysis to this medium alone, specifically in respect of glow curve and fading study. In addition, elemental compositional and structural change characterizations were made for the same medium, utilizing Energy Dispersive X-Ray (EDX) and Raman spectroscopy, respectively.
A single sample from the logged section at eastern side of Gua Panjang limestone hill, southwest of Kampung Kubang
Rasa Village, Merapoh, has yielded 5 very important conodont species. They are Hindeodus parvus erectus, Hindeodus
parvus parvus, Hindeodus latidentatus latidentatus, Hindeodus latidentatus praeparvus, Hindeodus postparvus, Hindeodus
eurypge and Isarcicella staeschi. These Early Triassic conodonts were obtained in a bioclastic dolostone sample, located
2.5 m above bioclastic grainstone which yielded Late Permian foraminifera. The conodonts found were given Conodont
Alteration Index (CAI) scale of 5, consistent with the heating of Main Range granitoid during Indosinian Orogeny.
Limestone harbouring basal Triassic conodonts in Gua Panjang is interpreted to be deposited in an open shallow marine
shelf environment.
The durability of natural and treated clay soil stabilized with lime and alkaline activation (AA) affected by environmental factors (hot and humid) was determined in this study. Investigation and evaluation on the strength of the soil, moisture content, and volume change of the specimen were determined at each curing period (7, 28, and 90 days) based on the weather conditions. An unconfined compressive strength (UCS) of the specimen at three different wetting/drying cycles (one, three, and five cycles) was determined. The findings show that the strength of the treated specimens fluctuated with increment and decrement strength (one and three cycles) in the range of 1.41 to 1.88 MPa (lime) and 2.64 to 8.29 MPa (AA), while for five cycles with a curing period of 90 days the decrement was in the range of 1.62 to 1.25 MPa and 6.06 to 5.89 MPa for lime and AA, respectively. The decrement percentage for treated samples that were subjected to five cycles of wetting and drying in 90 days was found to be 20.38% (lime) and 38.64% (AA), respectively. Therefore, it can be summarized that wetting/drying cycles have a significant influence on the durability, strength, and the volume changes of the specimens.
Microwave assisted wet precipitation method was used to synthesize calcium deficient strontium doped β-tricalcium phosphate (Sr-βTCP) with a chemical formula of Ca2.96-xSrx(PO4)2. Sr-βTCP was reacted with monocalcium phosphate monohydrate [Ca(H2PO4)2.H2O, MCPM] in presence of water to furnish corresponding Sr containing brushite cement (Sr-Brc). The samples were characterized by using X-ray diffractometry (XRD), Fourier transform infrared spectroscopy (FTIR) and field emission scanning electron microscopy (FESEM). Strontium content in the prepared samples was determined by using inductively coupled plasma optical emission spectrometry (ICP-OES). The effect of Sr2+ions on the structural, mechanical, setting properties and drug release of the cement is reported. Incorporation of Sr2+ions improved the injectability, setting time and mechanical properties of the Brc. The release profiles of antibiotics incorporated in Brc and Sr-Brc confirmed that the Sr incorporation into the Brc results in the efficient release of the antibiotics from the cement.
Metal nanoparticles prepared by exsolution at the surface of perovskite oxides have been recently shown to enable new dimensions in catalysis and energy conversion and storage technologies owing to their socketed, well-anchored structure. Here we show that contrary to general belief, exsolved particles do not necessarily re-dissolve back into the underlying perovskite upon oxidation. Instead, they may remain pinned to their initial locations, allowing one to subject them to further chemical transformations to alter their composition, structure and functionality dramatically, while preserving their initial spatial arrangement. We refer to this concept as chemistry at a point and illustrate it by tracking individual nanoparticles throughout various chemical transformations. We demonstrate its remarkable practical utility by preparing a nanostructured earth abundant metal catalyst which rivals platinum on a weight basis over hundreds of hours of operation. Our concept enables the design of compositionally diverse confined oxide particles with superior stability and catalytic reactivity.
A study was carried out to optimize the deacidification process for noni (Morinda citrifolia L.) extract using packed column of calcium carbonate. The experiments were based on a 3-level factorial design to study the optimum process of deacidification for M. citrifolia extract. The M. citrifolia extract was treated with CaCO3 packed in different column diameter (20, 25 and 30 mm), height of calcium carbonate (0, 0.5 and 1 cm) and feed rate (10, 30 and 50 ml/min). Physico-chemical characteristics which include pH, titratable acidity, turbidity, total polyphenol content and total soluble solids were measured. Results showed that only pH, titratable acidity and turbidity could be well represented using statistical models. For pH, only the effect of height of CaCO3 was found to be significant. While for titratable acidity and turbidity, effects of diameter column and height of CaCO3 were significant. The optimum conditions for the deacidification of M. citrifolia extract was by using a column diameter of 30 mm, CaCO3 height of 1 cm, and a feed rate of 50 ml/min.
Despite the many attractive potential uses of ceramic materials as humidity sensors, some unavoidable drawbacks, including toxicity, poor biocompatibility, long response and recovery times, low sensitivity and high hysteresis have stymied the use of these materials in advanced applications. Therefore, in present investigation, we developed a capacitive humidity sensor using lead-free Ca,Mg,Fe,Ti-Oxide (CMFTO)-based electro-ceramics with perovskite structures synthesized by solid-state step-sintering. This technique helps maintain the submicron size porous morphology of the developed lead-free CMFTO electro-ceramics while providing enhanced water physisorption behaviour. In comparison with conventional capacitive humidity sensors, the presented CMFTO-based humidity sensor shows a high sensitivity of up to 3000% compared to other materials, even at lower signal frequency. The best also shows a rapid response (14.5 s) and recovery (34.27 s), and very low hysteresis (3.2%) in a 33%-95% relative humidity range which are much lower values than those of existing conventional sensors. Therefore, CMFTO nano-electro-ceramics appear to be very promising materials for fabricating high-performance capacitive humidity sensors.
Perovskite solar cells based on series of inorganic cesium lead bromide and iodide mixture, CsPbBr3-xI x , where x varies between 0, 0.1, 0.2, and 0.3 molar ratio were synthesized by two step-sequential deposition at ambient condition to design the variations of wide band gap light absorbers. A device with high overall photoconversion efficiency of 3.98 % was obtained when small amount of iodide (CsPbBr2.9I0.1) was used as the perovskite and spiro-OMeTAD as the hole transport material (HTM). We investigated the origin of variation in open circuit voltage, Voc which was shown to be mainly dependent on two factors, which are the band gap of the perovskite and the work function of the HTM. An increment in Voc was observed for the device with larger perovskite band gap, while keeping the electron and hole extraction contacts the same. Besides, the usage of bilayer P3HT/MoO3 with deeper HOMO level as HTM instead of spiro-OMeTAD, thus increased the Voc from 1.16 V to 1.3 V for CsPbBr3 solar cell, although the photocurrent is lowered due to charge extraction issues. The stability studies confirmed that the addition of small amount of iodide into the CsPbBr3 is necessarily to stabilize the cell performance over time.
2D perovskites is one of the proposed strategies to enhance the moisture resistance, since the larger organic cations can act as a natural barrier. Nevertheless, 2D perovskites hinder the charge transport in certain directions, reducing the solar cell power conversion efficiency. A nanostructured mixed-dimensionality approach is presented to overcome the charge transport limitation, obtaining power conversion efficiencies over 9%.