Displaying publications 1 - 20 of 31 in total

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  1. A novel cultivation platform of duckweed (Lemna minor) via application of beeswax superhydrophobic coatings
    Chua MX, Cheah YT, Tan WH, Chan DJC
    Environ Res, 2023 May 01;224:115544.
    PMID: 36822535 DOI: 10.1016/j.envres.2023.115544
    Conventional establishment of laboratory cultures of duckweed Lemna minor are prepared in beakers, Erlenmeyer flasks or Schott bottles. These conventional cultivation methods limit the available surface area for growth which then causes layering of fronds that reduces the efficiency of plants in sunlight capturing. Here, acrylic sheets were spray-coated with a superhydrophobic (SHP) beeswax suspension and these coated acrylic sheets were used as a novel cultivation platform for L. minor. L. minor was grown for 7 days in conventional glass jar which acted as the control and were compared to SHP coated acrylic (SHPA) and SHP coated acrylic with aluminium mesh centrally placed (SHPAM) at similar duration and cultivation conditions. Addition of mesh was to entrap the plantlets and fixed the plantlets' position on the growing platform. The effects of cultivation platforms on growth rate and biochemical compositions of L. minor were monitored. The highest biomass growth was obtained from SHPA cultivation where the relative growth rate (RGR) was 0.0909 ± 0.014 day-1 and the RGR was 2.17 times higher than the control. Moreover, L. minor harvested from SHPA displayed the highest values in total protein content, total carbohydrates content and crude lipid percentage. The values were 156.04 ± 12.13 mg/g, 94.75 ± 9.02 mg/g and 7.09 ± 1.14% respectively. However, the control showed the highest total chlorophyll content which was 0.7733 ± 0.042 mg/g FW. Although SHPA obtained a slightly lower chlorophyll content than the control, this growing platform is still promising as it displayed the highest growth rate as well as other biochemical composition. Hence, this study proved that the proposed method that applied superhydrophobic properties in cultivation of L. minor provided a larger surface area for L. minor to grow, which then resulted in a greater biomass production while simultaneously maintaining the quality of the biochemical compositions of duckweeds.
    Matched MeSH terms: Waxes/metabolism; Waxes/pharmacology
  2. Fulltext Vacuum/compression valving (VCV) using parrafin-wax on a centrifugal microfluidic CD platform
    Al-Faqheri W, Ibrahim F, Thio TH, Moebius J, Joseph K, Arof H, et al.
    PLoS One, 2013;8(3):e58523.
    PMID: 23505528 DOI: 10.1371/journal.pone.0058523
    This paper introduces novel vacuum/compression valves (VCVs) utilizing paraffin wax. A VCV is implemented by sealing the venting channel/hole with wax plugs (for normally-closed valve), or to be sealed by wax (for normally-open valve), and is activated by localized heating on the CD surface. We demonstrate that the VCV provides the advantages of avoiding unnecessary heating of the sample/reagents in the diagnostic process, allowing for vacuum sealing of the CD, and clear separation of the paraffin wax from the sample/reagents in the microfluidic process. As a proof of concept, the microfluidic processes of liquid flow switching and liquid metering is demonstrated with the VCV. Results show that the VCV lowers the required spinning frequency to perform the microfluidic processes with high accuracy and ease of control.
    Matched MeSH terms: Waxes*
  3. Bacteria consortia enhanced hydrocarbon degradation of waxy crude oil
    Rahman RNZRA, Latip W, Adlan NA, Sabri S, Ali MSM
    Arch Microbiol, 2022 Nov 12;204(12):701.
    PMID: 36370212 DOI: 10.1007/s00203-022-03316-8
    Waxy crude oil is a problem to the oil and gas industry because wax deposition in pipelines reduces the quality of the crude oil. Currently, the industry uses chemicals to solve the problem but it is not environmentally friendly. As an alternative, the biodegradation approach is one of the options. Previously eleven thermophilic bacteria were isolated and exhibited high ability to degrade hydrocarbon up to 70% of waxy crude oil. However, despite the successful study on these single bacteria strains, it is believed that biodegradation of paraffin wax requires more than a single species. Five consortia were developed based on the biodegradation efficiency of 11 bacterial strains. Consortium 3 showed the highest biodegradation (77.77%) with more long-chain alkane degraded throughout the incubation compared to other consortia. Enhancement of hydrocarbon degradation was observed for all consortia especially in long chain alkane (C18-C40). Consortium 3 exhibited higher alkane monooxygenase, alcohol dehydrogenase, lipase, and esterase activities. Moreover, the dominant bacteria in the consortia were determined by denaturing gradient gel electrophoresis (DGGE), which showed the domination of genera Geobacillus, Parageobacillus, and Anoxybacillus. It can be concluded that the bacterial consortia showed higher biodegradation and improved degrading more long-chain hydrocarbon compared to a single isolate.
    Matched MeSH terms: Waxes/metabolism
  4. Synergistic interactions between lecithin and fruit wax in oleogel formation
    Okuro PK, Tavernier I, Bin Sintang MD, Skirtach AG, Vicente AA, Dewettinck K, et al.
    Food Funct, 2018 Mar 01;9(3):1755-1767.
    PMID: 29508864 DOI: 10.1039/c7fo01775h
    In this study, the effect of lecithin (LEC) on the crystallization and gelation of fruit wax (FW) with sunflower oil was researched. A synergistic effect on the gel strength was observed at FW : LEC ratios of 75 : 25 and 50 : 50, compared to the corresponding single component formulations (100 : 0 and 0 : 100). Even below the critical gelling concentration (Cg) of FW, the addition of lecithin enabled gel formation. Lecithin affected the thermal behavior of the structure by delaying both crystallization and gel formation. The phospholipid acted as a crystal habit modifier changing the microstructure of the oleogel, as was observed by polarized light microscopy. Cryo-scanning electron microscopy revealed a similar platelet-like arrangement for both FW as a single oleogelator and FW in combination with LEC. However, a denser structure could be observed in the FW : LEC oleogelator mixture. Both the oil-binding capacity and the thixotropic recovery were enhanced upon lecithin addition. These improvements were attributed to the hydrogen bonding between FW and LEC, as suggested by Raman spectroscopy. We hypothesized that lecithin alters the molecular assembly properties of the FW due to the interactions between the polar moieties of the oleogelators, which consequently impacts the hydrophobic tail (re)arrangement in gelator-gelator and solvent-gelator interactions. The lipid crystal engineering approach followed here offered prospects of obtaining harder self-standing structures at a lower oleogelator concentration. These synergistic interactions provide an opportunity to reduce the wax concentration and, as such, the waxy mouthfeel without compromising the oleogel properties.
    Matched MeSH terms: Waxes/chemistry*
  5. Fulltext A review on plant importance, biotechnological aspects, and cultivation challenges of jojoba plant
    Al-Obaidi JR, Halabi MF, AlKhalifah NS, Asanar S, Al-Soqeer AA, Attia MF
    Biol Res, 2017 Aug 24;50(1):25.
    PMID: 28838321 DOI: 10.1186/s40659-017-0131-x
    Jojoba is considered a promising oil crop and is cultivated for diverse purposes in many countries. The jojoba seed produces unique high-quality oil with a wide range of applications such as medical and industrial-related products. The plant also has potential value in combatting desertification and land degradation in dry and semi-dry areas. Although the plant is known for its high-temperature and high-salinity tolerance growth ability, issues such as its male-biased ratio, relatively late flowering and seed production time hamper the cultivation of this plant. The development of efficient biotechnological platforms for better cultivation and an improved production cycle is a necessity for farmers cultivating the plant. In the last 20 years, many efforts have been made for in vitro cultivation of jojoba by applying different molecular biology techniques. However, there is a lot of work to be done in order to reach satisfactory results that help to overcome cultivation problems. This review presents a historical overview, the medical and industrial importance of the jojoba plant, agronomy aspects and nutrient requirements for the plant's cultivation, and the role of recent biotechnology and molecular biology findings in jojoba research.
    Matched MeSH terms: Waxes*
  6. Fulltext Optimization of natural lipstick formulation based on pitaya (Hylocereus polyrhizus) seed oil using D-optimal mixture experimental design
    Kamairudin N, Gani SS, Masoumi HR, Hashim P
    Molecules, 2014;19(10):16672-83.
    PMID: 25325152 DOI: 10.3390/molecules191016672
    The D-optimal mixture experimental design was employed to optimize the melting point of natural lipstick based on pitaya (Hylocereus polyrhizus) seed oil. The influence of the main lipstick components-pitaya seed oil (10%-25% w/w), virgin coconut oil (25%-45% w/w), beeswax (5%-25% w/w), candelilla wax (1%-5% w/w) and carnauba wax (1%-5% w/w)-were investigated with respect to the melting point properties of the lipstick formulation. The D-optimal mixture experimental design was applied to optimize the properties of lipstick by focusing on the melting point with respect to the above influencing components. The D-optimal mixture design analysis showed that the variation in the response (melting point) could be depicted as a quadratic function of the main components of the lipstick. The best combination of each significant factor determined by the D-optimal mixture design was established to be pitaya seed oil (25% w/w), virgin coconut oil (37% w/w), beeswax (17% w/w), candelilla wax (2% w/w) and carnauba wax (2% w/w). With respect to these factors, the 46.0 °C melting point property was observed experimentally, similar to the theoretical prediction of 46.5 °C. Carnauba wax is the most influential factor on this response (melting point) with its function being with respect to heat endurance. The quadratic polynomial model sufficiently fit the experimental data.
    Matched MeSH terms: Waxes/chemistry*
  7. Kinetics of enzymatic synthesis of liquid wax ester from oleic acid and oleyl alcohol
    Radzi SM, Mohamad R, Basri M, Salleh AB, Ariff A, Rahman MB, et al.
    J Oleo Sci, 2010;59(3):127-34.
    PMID: 20124754
    The kinetics of wax ester synthesis from oleic acid and oleyl alcohol using immobilized lipase from Candida antartica as catalyst was studied with different types of impeller (Rushton turbine and AL-hydrofoil) to create different mixing conditions in 2l stirred tank reactor. The effects of catalyst concentration, reaction temperature, and impeller tip speed on the synthesis were also evaluated. Rushton turbine impeller exhibited highest conversion rate at lower impeller tip speed as compared to AL-hydrofoil impeller. A second-order reversible kinetic model from single progress curve for the prediction of fractional conversion at given reaction time was proposed and the corresponding kinetic parameter values were calculated by non-linear regression method. The results from the simulation using the proposed model showed satisfactory agreement with the experimental data. Activation energy shows a value of 21.77 Kcal/mol. The thermodynamic parameters of the process, enthalpy and entropy, were 21.15 Kcal/mol and 52.07 cal/mol.K, respectively.
    Matched MeSH terms: Waxes/metabolism*
  8. Gamma irradiation of corn starches with different amylose-to-amylopectin ratio
    Chung KH, Othman Z, Lee JS
    J Food Sci Technol, 2015 Oct;52(10):6218-29.
    PMID: 26396368 DOI: 10.1007/s13197-014-1700-4
    Corn starches with different amylose-to-amylopectin ratio (waxy, normal, Hylon V, and Hylon VII) were treated with five doses of gamma irradiation (1, 5, 10, 25, and 50 kGy). The effects of gamma irradiation on the physicochemical properties of starch samples were investigated. Waxy samples showed an increase of amylose-like fractions when irradiated at 10 kGy. The reduction in apparent amylose content increased with amylose content when underwent irradiation at 25 and 50 kGy. Low amylose starches lost their pasting ability when irradiated at 25 and 50 kGy. Results from thermal behavior and pasting profile suggested that low level of cross-linking occurred in Hylon VII samples irradiated at 5 kGy. Severe reduction in pasting properties, gelatinization temperatures and relative crystallinity with increasing irradiation intensity revealed that waxy samples were affected more by gamma irradiation; this also indicated amylopectin was the starch fraction most affected by gamma irradiation. Alteration level was portrayed differently when different kind of physicochemical properties were investigated, in which the pasting properties and crystallinity of starches were more immensely influenced by gamma irradiation while thermal behavior was less affected. Despite the irradiation level, the morphology and crystal pattern of starch granules were found remain unchanged by irradiation.
    Matched MeSH terms: Waxes
  9. Fulltext Granuloma formation and loss of tooth vitality following the use of bone wax in third molar surgery: rep ort of a case
    Raman, Rajeswary, Yap, Hsiao Fern
    Archives of Orofacial Sciences, 2014;9(1):1-3.
    MyJurnal
    In the present case, granuloma formation and loss of tooth vitality following the use of bone wax in third molar surgery in a 16 - year- old male patient were reported. Endodontic and surgical treatments were carried out on the patient. As foreign body granulomatous reaction to bone wax is not uncommon in the literature review, alternative haemostatic agents should be taken into consideration to avoid any potential complications and untoward effects of using bone wax for haemorrhage control in surgical procedures.
    Matched MeSH terms: Waxes
  10. Fulltext Fast Melt Cocoa Butter Tablet: Effect of Waxes, Starch, and PEG 6000 on Physical Properties of the Preparation
    Liew KB, Ming LC, Goh BH, Peh KK
    Molecules, 2022 May 13;27(10).
    PMID: 35630605 DOI: 10.3390/molecules27103128
    A fast melt tablet (FMT) is well regarded as an alternative delivery system that might help resolve a patient's non-compliance issue. The main objective of this study was to develop a cocoa butter-based FMT. Additives, namely 5-15% of PEG 6000, beeswax, paraffin wax, and corn starch, were incorporated into the cocoa butter-based FMT to study the effects of these additives with the physical characteristic of a cocoa butter FMT. An optimum-based formulation was chosen according to the desired hardness and disintegration time and the taste masking property achieved with the model drug-dapoxetine. The analysis demonstrated that incorporating beeswax (15%) and paraffin wax (15%) could prolong the disintegration time by at least two-fold. On the contrary, the presence of corn starch was found to cause an increase in the hardness and reduction of the disintegration time. The disintegration mechanism might be presumed due to the synergistic effect of starch swelling and cocoa butter melting. The hardness value and in vitro disintegration time of the optimum formulation were recorded at 2.93 ± 0.22 kg and 151.67 ± 6.98 s. In terms of dissolution, 80% of dapoxetine was released within 30 min and the dissolution profile was comparable to the innovator product. The formulation was palatable and stable for at least 1 year. The exposure of the FMT formulation at 30 °C for 12 months was reported to be stable. Along with the sound palatability profile and high drug load capacity, the current formulation possesses the desired characteristics to be scaled up and marketed.
    Matched MeSH terms: Waxes
  11. Comparison of estimation capabilities of response surface methodology (RSM) with artificial neural network (ANN) in lipase-catalyzed synthesis of palm-based wax ester
    Basri M, Rahman RN, Ebrahimpour A, Salleh AB, Gunawan ER, Rahman MB
    BMC Biotechnol, 2007;7:53.
    PMID: 17760990
    Wax esters are important ingredients in cosmetics, pharmaceuticals, lubricants and other chemical industries due to their excellent wetting property. Since the naturally occurring wax esters are expensive and scarce, these esters can be produced by enzymatic alcoholysis of vegetable oils. In an enzymatic reaction, study on modeling and optimization of the reaction system to increase the efficiency of the process is very important. The classical method of optimization involves varying one parameter at a time that ignores the combined interactions between physicochemical parameters. RSM is one of the most popular techniques used for optimization of chemical and biochemical processes and ANNs are powerful and flexible tools that are well suited to modeling biochemical processes.
    Matched MeSH terms: Waxes/metabolism; Waxes/chemistry*
  12. Fulltext Influence of exposure time to coffee on color stability of selected composite resin veneers
    Thiyab, Amar M., Mahmood, Nik Zarina N., Hassan, Mohamed Ibrahim A.
    Compendium of Oral Science, 2016;3(1):9-16.
    MyJurnal
    Objectives: The aim of the study is to evaluate the effect of the time and instant coffee solution on the color stability of three types of composite resin based veneer systems. Materials and Methods: 24 composite resin veneer samples were selected and divided into three groups: two groups of prefabricated veneers (Edelweiss, Ultradent Inc™ (EDL) and Componeer, Coltène/ Whaledent AGTM (CMP)) and one group of laboratory made (Nexco, Ivoclar Vivadent (NEX)) veneer system were tested (n=8). Specimens were prepared and stored in staining solution (instant coffee) and assessed color changes with Minolta spectrophotometer every three days for a period of 27 days, after which color differences (ΔE*) were calculated. Data collection and analysis was done using one-way ANOVA and Student’s t-test (α=0.05). Results: One-way ANOVA revealed a significant difference in color stability between the two veneer systems. NEX group veneer system exhibited the highest color stability (ΔE*= 0.73 ± 0.5) as compared to prefabricated veneer groups (EDL 10.07 ± 5.15, CMP 7.41 ± 4.64) with p value
    Matched MeSH terms: Waxes
  13. Fulltext Diabetic hidden gem: high amylose content in Sabah’s traditional rice germplasm [Abstract]
    Tyng CF, Fui LF, Abdul Latip M, Kumar V
    Malaysian Journal of Medicine and Health Sciences, 2019;15(106):17.
    MyJurnal
    ABSTRACTS FOR THE 1ST INTERNATIONAL BORNEO HEALTHCARE AND PUBLIC HEALTH CONFERENCE AND 4TH BORNEO TROPICAL MEDICINE AND INFECTIOUS DISEASE CONGRESS. New Frontiers in Health: Expecting the Unexpected. Held at the Faculty of Medicine and Health Sciences, Universiti Malaysia Sabah, Kota Kinabalu, Sabah, Malaysia. 3rd-5th September 2019
    Introduction: Rice is classified as waxy, very low, low, intermediate and high based on its amylose content (AC). Most people prefer to consume intermediate AC rice because of its texture which tends to appear in between low (moist and sticky) and high (dry and less tender). Although rice with high AC appears dry and less tender, it usually possesses a low glycemic index (GI) i.e. a slower increase in blood glucose level after the consumption of food. Consequently, people with diabetes are recommended to eat low and intermediate GI foods. Although, rice is generally categorised as a high GI staple food there are some exceptions to it. For example, the premium Basmati aromatic rice possesses a low GI and is recommended for diabetic patients. The study aimed to identify Sabah’s traditional rice germplasm with low GI via AC that may be used as a replacement to commercial rice varieties.
    Methods: A total of 110 traditional rice samples were obtained from rice fields located in the Tuaran and Kota Belud districts of Sabah. The AC in each sample was determined via I:KI method (ISO AACC-6647).
    Results: We found that 46 (41.8%), 51 (46.4%), 7 (6.4%) and 6 (5.5%) Sabah’s traditional rice samples possess high, intermediate, low and very low AC, respectively. The intermediate AC type is predominant in Sabah’s traditional rice germplasm as it is the preferred rice texture by the general population. We have identified 46 rice germplasm with high AC type (i.e. with low GI value). The AC content in these is comparable to the Basmati rice and may be suitable candidates for diabetic patients.
    Conclusion: The present study showed Sabah’s traditional rice germplasm has the potential to be promoted as a low GI rice cultivar based on AC for diabetic patients in order to prevent spikes in blood glucose levels while still enjoying the staple food
    Matched MeSH terms: Waxes
  14. Effects of Crude Palm Oil and Crude Palm Kernel Oil Upon Wax Inhibition
    Ragunathan T, Husin H, Wood CD
    ACS Omega, 2020 Aug 11;5(31):19342-19349.
    PMID: 32803027 DOI: 10.1021/acsomega.0c00753
    The ever-increasing demand for the finite source of oil has led oil production companies to produce and transport the produced crude oil as efficiently and economically as possible. One of the major concerns especially in waters like the South China Sea is the deposition of wax on the walls of the pipeline or wellbore, constricting and hindering the hydrocarbon flow. This is due to the low seabed temperatures, which can be below the wax appearance temperature (WAT), leading to the deposition of wax out of waxy crude oil through the molecular dispersion mechanism. Currently, many prevention and remedy methods are in place to overcome the problem, but most of the additives possess environmental threat, as most of the chemical solutions used are toxic, nonorganic, and costly. Hence, this paper aims to provide some insights into the effect of palm oil derivatives such as crude palm oil (CPO) and crude palm kernel oil (CPKO) on wax inhibition. The effect of aging time (i.e., immersion time) was also evaluated. A comparison was made between paraffin inhibition efficiency results (PIE %) obtained by CPO, CPKO, poly(ethylene-co-vinyl acetate) (EVA), and triethanolamine (TEA). It was observed that the average efficiency of 81.67% was obtained when 1% CPO was added to heavy crude oil. The wax inhibition performance reached a plateau after 1.5 h of aging time for all of the investigated samples.
    Matched MeSH terms: Waxes
  15. Fulltext Utilisation of palm – based and beeswax coating on the postharvest-life of guava (Psidium guajava L.) during ambient and chilled storage
    Ruzaina, I., Norizzah, A.R., Halimahton Zahrah, M.S., Cheow, C.S., Adi, M.S., Noorakmar, A.W., et al.
    International Food Research Journal, 2013;20(1):265-274.
    MyJurnal
    Guava is a climacteric fruit which has high nutritional content. It is a highly perishable fruit, undergoes rapid postharvest ripening in a few days under ambient condition. This paper aims to determine the effect of palm stearin and palm kernel olein blends on maintaining the quality of guava during storage. Two different coating formulations of palm stearin (PS) and palm kernel olein (PKOo) blends (1:1 and 3:2) were analysed for their slip melting point (SMP), cohesiveness, viscosity and density. Beeswax was used as a commercial coating for comparison whiles the uncoated guava was used as control. These coatings were applied onto guavas by hand-wipe technique using a sponge. Guavas were dried in corrugated fibre board boxes and stored in an air-conditioned room maintained at 20°C while a chiller maintained at 10°C was used for chilled temperature. Coating pick up, thickness and surface area were measured while guava properties were analysed for coating effect on weight loss, O2 and CO2 gases, firmness and glossiness during storage at ambient temperature (20°C) for 21 days and chilled temperature (10ºC) for 30 days. Microstructure analysis was conducted within 2 days of coating at ambient temperature (20ºC). The results obtained indicated that 1:1 PSPKOo blends had higher cohesiveness compared to beeswax. Both PSPKOo blends significantly (p
    Matched MeSH terms: Waxes
  16. Fulltext The Effect of Cavity Design on Fracture Resistance and Failure Pattern in Monolithic Zirconia Partial Coverage Restorations - An In vitro Study
    Harsha MS, Praffulla M, Babu MR, Leneena G, Krishna TS, Divya G
    J Clin Diagn Res, 2017 May;11(5):ZC45-ZC48.
    PMID: 28658906 DOI: 10.7860/JCDR/2017/25305.9856
    INTRODUCTION: Cavity preparations of posterior teeth have been frequently associated with decreased fracture strength of the teeth. Choosing the correct indirect restoration and the cavity design when restoring the posterior teeth i.e., premolars was difficult as it involves aesthetic, biomechanical and anatomical considerations.

    AIM: To evaluate the fracture resistance and failure pattern of three different cavity designs restored with monolithic zirconia.

    MATERIALS AND METHODS: Human maxillary premolars atraumatically extracted for orthodontic reasons were chosen. A total of 40 teeth were selected and divided into four groups (n=10). Group I-Sound teeth (control with no preparation). Group II-MOD Inlay, Group III-Partial Onlay, Group IV-Complete Onlay. Restorations were fabricated with monolithic partially sintered zirconia CAD (SAGEMAX- NexxZr). All the 30 samples were cemented using Multilink Automix (Ivoclar) and subjected to fracture resistance testing using Universal Testing Machine (UTM) (Instron) with a steel ball of 3.5 mm diameter at crosshead speed of 0.5 mm/minute. Stereomicroscope was used to evaluate the modes of failure of the fractured specimen. Fracture resistance was tested using parametric one way ANOVA test, unpaired t-test and Tukey test. Fracture patterns were assessed using non-parametric Chi-square test.

    RESULTS: Group IV (Complete Onlay) presented highest fracture resistance and showed statistical significant difference. Group II (MOD Inlay) and Group III (Partial Onlay) showed significantly lower values than the Group I (Sound teeth). However, Groups I, II and III presented no significant difference from each other. Coming to the modes of failure, Group II (MOD Inlay) and Group III (Partial Onlay) presented mixed type of failures; Group IV (Complete Onlay) demonstrated 70% Type I failures.

    CONCLUSION: Of the three cavity designs evaluated, Complete Onlay had shown a significant increase in the fracture resistance than the Sound teeth.

    Matched MeSH terms: Waxes
  17. Fulltext Fluid-solid phase transition of n-alkane mixtures: Coarse-grained molecular dynamics simulations and diffusion-ordered spectroscopy nuclear magnetic resonance
    Shahruddin S, Jiménez-Serratos G, Britovsek GJP, Matar OK, Müller EA
    Sci Rep, 2019 Jan 30;9(1):1002.
    PMID: 30700804 DOI: 10.1038/s41598-018-37799-7
    Wax appearance temperature (WAT), defined as the temperature at which the first solid paraffin crystal appears in a crude oil, is one of the key flow assurance indicators in the oil industry. Although there are several commonly-used experimental techniques to determine WAT, none provides unambiguous molecular-level information to characterize the phase transition between the homogeneous fluid and the underlying solid phase. Molecular Dynamics (MD) simulations employing the statistical associating fluid theory (SAFT) force field are used to interrogate the incipient solidification states of models for long-chain alkanes cooled from a melt to an arrested state. We monitor the phase change of pure long chain n-alkanes: tetracosane (C24H50) and triacontane (C30H62), and an 8-component surrogate n-alkane mixture (C12-C33) built upon the compositional information of a waxy crude. Comparison to Diffusion Ordered Spectroscopy Nuclear Magnetic Resonance (DOSY NMR) results allows the assessment of the limitations of the coarse-grained models proposed. We show that upon approach to freezing, the heavier components restrict their motion first while the lighter ones retain their mobility and help fluidize the mixture. We further demonstrate that upon sub-cooling of long n-alkane fluids and mixtures, a discontinuity arises in the slope of the self-diffusion coefficient with decreasing temperature, which can be employed as a marker for the appearance of an arrested state commensurate with conventional WAT measurements.
    Matched MeSH terms: Waxes
  18. Fulltext Characterization of rice bran wax policosanol and its nanoemulsion formulation
    Ishaka A, Umar Imam M, Mahamud R, Zuki AB, Maznah I
    Int J Nanomedicine, 2014;9:2261-9.
    PMID: 24872689 DOI: 10.2147/IJN.S56999
    Policosanol, a mixture of long-chain alcohols found in animal and plant waxes, has several biological effects; however, it has a bioavailability of less than 10%. Therefore, there is a need to improve its bioavailability, and one of the ways of doing this is by nanoemulsion formulation. Different droplet size distributions are usually achieved when emulsions are formed, which solely depends on the preparation method used. Mostly, emulsions are intended for better delivery with maintenance of the characteristics and properties of the leading components. In this study, policosanol was extracted from rice bran wax, its composition was determined by gas chromatography mass spectrophotometry, nanoemulsion was made, and the physical stability characteristics were determined. The results showed that policosanol nanoemulsion has a nanosize particle distribution below 100 nm (92.56-94.52 nm), with optimum charge distribution (-55.8 to -45.12 mV), pH (6.79-6.92) and refractive index (1.50); these were monitored and found to be stable for 8 weeks. The stability of policosanol nanoemulsion confers the potential to withstand long storage times.
    Matched MeSH terms: Waxes/chemistry*
  19. Thermoplastic starch/beeswax blend: Characterization on thermal mechanical and moisture absorption properties
    Diyana ZN, Jumaidin R, Selamat MZ, Suan MSM
    Int J Biol Macromol, 2021 Nov 01;190:224-232.
    PMID: 34481857 DOI: 10.1016/j.ijbiomac.2021.08.201
    Cassava starch has acquired many attentions owing to its ability to be developed as thermoplastic cassava starch (TPCS) where it can be obtained in low cost, making it to be one of alternatives to substitute petroleum-based plastic. An attempt was made to investigate the thermal, mechanical and moisture absorption properties of thermoplastic cassava starch blending with beeswax (TPCS-BW) fabricated using hot moulding compression method in the range of beeswax loading from 0, 2.5, 5 to 10 wt%. Addition of beeswax has significantly reduced tensile strength, elongation and flexural strength while improving tensile modulus and flexural modulus until 5 wt% beeswax. Incorporation of 10 wt% beeswax has successfully produced the lowest value of moisture absorption and water solubility among the bio-composite which might be attributed to the beeswax's hydrophobic properties in improving water barrier of the TPCS-BW bio-composite. Furthermore, the addition of beeswax resulted in the appearance of irregular and rough fractured surface. Meanwhile, fourier transform infrared (FT-IR) spectroscopy presented that incorporation of beeswax in the mixture has considerably improve hydrogen bonding of blends indicating good interaction between starch and beeswax. Hence, beeswax with an appropriate loading value able to improve the functional properties of TPCS-BW bio-composite.
    Matched MeSH terms: Waxes/chemistry*
  20. Fulltext Carnauba Wax/Halloysite Nanotube with Improved Anti-Wetting and Permeability of Hydrophobic PVDF Membrane via DCMD
    AbdulKadir WAFW, Ahmad AL, Boon Seng O
    Membranes (Basel), 2021 Mar 23;11(3).
    PMID: 33807017 DOI: 10.3390/membranes11030228
    The hydrophobic membranes have been widely explored to meet the membrane characteristics for the membrane distillation (MD) process. Inorganic metal oxide nanoparticles have been used to improve the membrane hydrophobicity, but limited studies have used nano clay particles. This study introduces halloysite nanotube (HNT) as an alternative material to synthesis a hydrophobic poly(vinylidene fluoride) (PVDF)-HNT membrane. The PVDF membranes were fabricated using functionalized HNTs (e.g., carnauba wax and 1H,1H,2H,2H-perfluorooctyl-trichlorosilane (FOTS)). The results were determined by Fourier transform infrared-attenuated total reflection, scanning electron microscope, goniometer and porometer to determine the desired hydrophobic membrane for direct contact membrane distillation (DCMD). The addition of FOTS-HNT (fs-HNT) and carnauba wax-HNT (fw-HNT) in the PVDF membrane enhanced the water contact angle (CA) to 127° and 137°, respectively. The presence of fw-HNT in the PVDF membrane exhibited higher liquid entry pressure (LEP) (2.64 bar) compared to fs-HNT in the membrane matrix (1.44 bar). The PVDF/fw-HNT membrane (Pfw-HNT) obtained the highest flux of 7.24 L/m2h with 99.9% salt removal. A stable permeability in the Pfw-HNT membrane was obtained throughout 16 h of DCMD. The incorporation of fw-HNT in the PVDF membrane had improved the anti-wetting properties and the membrane performance with the anti-fouling effect.
    Matched MeSH terms: Waxes
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