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Latex allergy diagnosis: in vivo and in vitro standardization of a natural rubber latex extract

Turjanmaa K, Palosuo T, Alenius H, Leynadier F, Autegarden JE, André C, et al.

Allergy, 1997 Jan;52(1):41-50.
PMID: 9062628

For the diagnosis of IgE-mediated (immediate) hypersensitivity to natural rubber latex (NRL), skin prick testing with extracts of latex gloves has been widely used, but such extracts are difficult to standardize. The present study aimed to produce on an industrial scale an NRL extract from freshly collected NRL and to evaluate, calibrate, and standardize the extract by both in vivo and in vitro testing. The source material, latex of the rubber tree, Hevea brasiliensis (clone RRIM 600), was frozen immediately after collection in Malaysia and shipped in dry ice to Stallergènes SA, France. Protein and allergen profiles were analyzed by sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE), immunoblotting, isoelectric focusing (IEF), crossed immunoelectrophoresis (CIE), and crossed radioimmunoelectrophoresis (CRIE). Allergen quantification was effected by RAST inhibition. The capacity of the preparation to elicit immediate hypersensitivity reactions in vivo was measured by skin prick testing in 46 latex-allergic patients and 76 nonallergic control subjects. SDS-PAGE and immunoblot profiles of the extract and an NRL standard (E8) provided by the US Food and Drug Administration were almost identical, disclosing several distinct IgE-binding proteins with apparent molecular weights of 14, 20, 27, 30, and 45 kDa, conforming to reported molecular weights of several significant NRL allergens. An arbitrary index of reactivity (IR) of 100 was assigned to the extract at 1:200 dilution (w/v), having a protein content of 22 micrograms/ml. Skin prick testing of latex-allergic patients and controls using the extract at 100 IR revealed 93% sensitivity, 100% specificity, 100% negative predictive value, and 96% positive predictive value. In conclusion, a skin prick test reagent for diagnosis of type I NRL allergy was successfully standardized. The reagent was demonstrated to contain most, if not all, of the currently known clinically significant NRL allergens, and it showed high sensitivity and specificity.

Matched MeSH terms: Rubber/administration & dosage; Rubber/analysis; Rubber/standards*
Fulltext Effect of high silica loading on uncured properties of epoxidised natural rubber compounds

Mazlina, M.K., Che Su, M.S.

ASM Science Journal, 2012;6(1):31-37.
MyJurnal

A 'green tyre' concept has the advantage of low rolling resistance, improved wet grip and enhanced handling. It has been reported that 3% decrease in rolling resistance is equivalent to 1% fuel saving, thus giving the 'green tyre' economic benefits and customer satisfaction. In this study, epoxidised natural rubber (ENR) compounds containing various loading of silica filler were prepared. The processibility and viscoelastic properties were investigated using the rubber processing analyser and Mooney viscometer. Results showed that the properties were adversely affected by the poor dispersion of silica as supported by the bound rubber measurement. In addition, a reversion in the cure behaviour was also observed as the curing temperature was increased to 170ºC.

Matched MeSH terms: Rubber
Fulltext Effect of epoxidized natural rubber on mechanical properties of epoxy reinforced kenaf fibre composites

Abu Bakar, M.A., Ahmad, S., Kuntjoro, W.

Pertanika Journal of Science & Technology, 2012;20(1):129-137.
MyJurnal

Kenaf fibre that is known as Hibiscus cannabinus, L. family Malvaceae is an herbaceous plant that can be grown under a wide range of weather conditions. The uses of kenaf fibres as a reinforcement material in the polymeric matrix have been widely investigated. It is known that epoxy has a disadvantage of brittleness and exhibits low toughness. In this research, liquid epoxidized natural rubber (LENR) was introduced to the epoxy to increase its toughness. Kenaf fibres, with five different fibre loadings of 5%, 10%, 15%, 20% and 25% by weight, were used to reinforce the epoxy resins (with and without addition of epoxidized natural rubber) as the matrices. The flexural strength, flexural modulus and fracture toughness of the rubber toughened epoxy reinforced kenaf fibre composites were investigated. The results showed that the addition of liquid epoxidized natural rubber (LENR) had improved the flexural modulus, flexural strength and fracture toughness by 48%, 30%, and 1.15% respectively at 20% fibre loading. The fractured surfaces of these composites were investigated by using scanning electron microscopic (SEM) technique to determine the interfacial bonding between the matrix and the fibre reinforcement.

Matched MeSH terms: Rubber
Fulltext Vulcanisation and coagulant dipping of epoxidised natural rubber latex

Dazylah Darji, Ma'zam Md Said

Pertanika Journal of Science & Technology, 2010;18(2):-.
MyJurnal

Epoxidised Natural Rubber (ENR) is now a commercially available polymer produced by chemical modification of natural rubber. Currently, three types of ENR are commercially available, and these are ENR 10, ENR 25, and ENR 50 with 10%, 25%, and 50% mol epoxidation, respectively. Studies on prevulcanisation of ENR 50 and postvulcanisation of the latex films were carried out. The objective of this study was to develop ENR 50 that could be dipped easily in coagulant dipping solution to produce dipped products. Several attempts were made by compounding prevulcanised ENR 50 at various sulphur levels ranging from 0.5 to 3.0 pphr. Using suitable coagulant dipping systems, ENR 50 film could be formed despite the high contents of non-ionic surfactant. It was found that the tensile strength of prevulcanised ENR 50 film decreased with the increase in the sulphur level. The results show that as level of sulphur increased, M300 also increased to an optimum value of 1.5 pphr of sulphur. For the postvulcanised ENR 50 film, however, the tensile strength increased and then decreased with the increasing sulphur level. Meanwhile M300 increased with the increasing postvulcanization time and sulphur level. The postvulcanisation of ENR 50 film seems to be a more effective way of increasing tensile properties than by prevulcanisation of ENR 50.

Matched MeSH terms: Rubber
Fulltext Detection of pipeline intelligent gauge jammed in pipeline by neutron device

Md Fakarudin Ab Rahman, Ismail Mustapha, Nor Pa’iza Mohd Hasan, Ibrahim, Pairu

Jurnal Sains Nuklear Malaysia, 2012;24(2):35-41.
MyJurnal

In industrial plants such as electricity generating, petroleum, chemical and petrochemical plants, pipelines are used extensively to transport liquid from one location to another. In radiation vulcanization of natural rubber latex (RVNRL) plants, pipelines are also used to transport latex to storage tank. During one of its maintenance activities, a pipeline intelligent gauge (PIG) that was used to monitor pipe integrity jammed inside the pipe causing interruption to its operation or loading activities. Sealed source technology was utilized to determine the location of jammed PIG in the pipeline. Fast neutrons from a 50 mCi Americium Beryllium (AmBe241), with energy range between 0.5 to11 MeV, were used for the study. Helium 3 (He3) detector was used to detect slow neutrons having a range of energy of 30 eV- 0.5 MeV. The investigation was carried out using neutron backscatter technique scanner. By adopting back-scattered technique, the location of jammed PIG in the pipeline has been successfully determined.

Matched MeSH terms: Rubber
Fulltext Some remarks on diurnal radon concentration at various locations in Peninsular Malaysia

Ahmad Saat, Zaini Hamzah, Zaharidah Abu Bakar, Zuraidah A. Munir, Siti Mariam Sumari, Misbah Hassan

Journal of Nuclear and Related Technologies, 2010;2010(1):49-57.
MyJurnal

A study was carried out to determine short term diurnal radon concentration at five locations in Malaysia. Two locations (KG & AP) are former tin mining areas that has been converted to housing area and training centre respectively, one a relatively new city (SA), that was formerly a rubber and oil palm plantation area, one older cities (KB) and one housing complex by the sea (LP). The study was carried out in 2005, 2006 and 2007 using a diffused-junction photodiode sensor continuous radon monitor. The monitor is recognized by the USEPA. In each location, measurements were carried out on at least ten sites. Former tin mining areas of KG and AP shows up to seven times higher indoor average than the average in the other three locations. However the indoor average in all locations is still below the action level of 4 pCiL-1. For outdoor, the former tin mining areas average concentration was higher than the global average of 0.4 pCiL-1. For the twenty four hours temporal variation the trend indicated that former tin mining areas concentration are always higher, and at time up to six fold higher. The hourly variation of all locations follows an identical trend of high concentration during early to late morning and drop in the afternoon till evening. The outdoor twenty four hour temporal average of former tin mining areas is consistently higher than the outdoor global average of 0.4 pCiL-1. The strong correlation between indoor and outdoor concentration at AP, indicates that indoor radon might originates from outdoor environment. The study was also extended to estimate the effective dose (mSvyr-1) of Rn-222 to the public.

Matched MeSH terms: Rubber
Fulltext Free-Radical Photopolymerization of Acrylonitrile Grafted onto Epoxidized Natural Rubber

Whba R, Su'ait MS, Tian Khoon L, Ibrahim S, Mohamed NS, Ahmad A

Polymers (Basel), 2021 Feb 23;13(4).
PMID: 33672185 DOI: 10.3390/polym13040660

The exploitation of epoxidized natural rubber (ENR) in electrochemical applications is approaching its limits because of its poor thermo-mechanical properties. These properties could be improved by chemical and/or physical modification, including grafting and/or crosslinking techniques. In this work, acrylonitrile (ACN) has been successfully grafted onto ENR- 25 by a radical photopolymerization technique. The effect of (ACN to ENR) mole ratios on chemical structure and interaction, thermo-mechanical behaviour and that related to the viscoelastic properties of the polymer was investigated. The existence of the -C≡N functional group at the end-product of ACN-g-ENR is confirmed by infrared (FT-IR) and nuclear magnetic resonance (NMR) analyses. An enhanced grafting efficiency (~57%) was obtained after ACN was grafted onto the isoprene unit of ENR- 25 and showing a significant improvement in thermal stability and dielectric properties. The viscoelastic behaviour of the sample analysis showed an increase of storage modulus up to 150 × 103 MPa and the temperature of glass transition (Tg) was between -40 and 10 °C. The loss modulus, relaxation process, and tan delta were also described. Overall, the ACN-g-ENR shows a distinctive improvement in characteristics compared to ENR and can be widely used in many applications where natural rubber is used but improved thermal and mechanical properties are required. Likewise, it may also be used in electronic applications, for example, as a polymer electrolyte in batteries or supercapacitor.

Matched MeSH terms: Rubber
Fulltext I-Tag: Patients stretcher innovation as a solution to injured patients mobilization

Kim Sooi Law, Noor Khairiah A. Karim, Noor Khairiah A. Karim, Nor Samsinar Abu Talib, Norhaliza Abd Hamid, Nur Arzuar Abdul Rahim, et al.

Jurnal Inovasi Malaysia, 2020;3(2):100-107.
MyJurnal

The paramedic team of Advanced Medical and Dental Institute (IPPT), Universiti Sains Malaysia (USM) is often involved in providing medical assistance for various activities organised by the university such as during PIMPIN siswa outdoor training and sport events. Paramedics often faced difficulty in saving injured patients as the current stretcher is rather heavy (5.8 kg) and is not able to be folded to a smaller size. To overcome this problem, i-TAG, a stretcher made of durable two-layer canvas cloth with the size of 170.0 cm x 74.0 cm and equipped with 10 user-friendly rubber handle, has been invented. The upper part of the stretcher has a zip to insert the spinal board if the victim has spinal and head injuries. The i-TAG is also very light with only 1.2 kg in weight, easy to be folded and stored in emergency bags, and can be easily carried by paramedics. The i-TAG innovative product has a positive impact on health and safety services. Using i-TAG, the task to carry patients or injured victims becomes easier, faster, saves energy and subsequently increases the efficacy of the rescue and medical aid tasks by paramedics.

Matched MeSH terms: Rubber
Effects of Running Surface Stiffness on Three-Segment Foot Kinematics Responses with Different Shod Conditions

Abdul Yamin NAA, Basaruddin KS, Salleh AF, Salim MS, Wan Muhamad WZA

Appl Bionics Biomech, 2021;2021:8842591.
PMID: 33603827 DOI: 10.1155/2021/8842591

Objective: The aim of this study was to investigate the effects of surface stiffness on multisegment foot kinematics and temporal parameters during running.
Methods: Eighteen male subjects ran on three different surfaces (i.e., concrete, artificial grass, and rubber) in both heeled running shoes (HS) and minimal running shoes (MS). Both these shoes had dissimilar sole profiles. The heeled shoes had a higher sole at the heel, a thick base, and arch support, whereas the minimal shoes had a flat base sole. Indeed, the studied biomechanical parameters responded differently in the different footwear during running. Subjects ran in recreational mode speed while 3D foot kinematics (i.e., joint rotation and peak medial longitudinal arch (MLA) angle) were determined using a motion capture system (Qualysis, Gothenburg, Sweden). Information on stance time and plantar fascia strain (PFS) was also collected.
Results: Running on different surface stiffness was found to significantly affect the peak MLA angles and stance times for both HS and MS conditions. However, the results showed that the joint rotation angles were not sensitive to surface stiffness. Also, PFS showed no relationship with surface stiffness, as the results were varied as the surface stiffness was changed.
Conclusion: The surface stiffness significantly contributed towards the effects of peak MLA angle and stance time. These findings may enhance the understanding of biomechanical responses on various running surfaces stiffness in different shoe conditions.

Matched MeSH terms: Rubber
Fulltext Performance Evaluation of Modified Rubberized Concrete Exposed to Aggressive Environments

M Mhaya A, Baghban MH, Faridmehr I, Huseien GF, Abidin ARZ, Ismail M

Materials (Basel), 2021 Apr 11;14(8).
PMID: 33920340 DOI: 10.3390/ma14081900

Recycling of the waste rubber tire crumbs (WRTCs) for the concretes production generated renewed interest worldwide. The insertion of such waste as a substitute for the natural aggregates in the concretes is an emergent trend for sustainable development towards building materials. Meanwhile, the enhanced resistance of the concrete structures against aggressive environments is important for durability, cost-saving, and sustainability. In this view, this research evaluated the performance of several modified rubberized concretes by exposing them to aggressive environments i.e., acid, and sulphate attacks, elevated temperatures. These concrete (12 batches) were made by replacing the cement and natural aggregate with an appropriate amount of the granulated blast furnace slag (GBFS) and WRTCs, respectively. The proposed mix designs' performance was evaluated by several measures, including the residual compressive strength (CS), weight loss, ultrasonic pulse velocity (UPV), microstructures, etc. Besides, by using the available experimental test database, an optimized artificial neural network (ANN) combined with the particle swarm optimization (PSO) was developed to estimate the residual CS of modified rubberized concrete after immersion one year in MgSO4 and H2SO4 solutions. The results indicated that modified rubberized concrete prepared by 5 to 20% WRTCs as a substitute to natural aggregate, provided lower CS and weight lose expose to sulphate and acid attacks compared to control specimen prepared by ordinary Portland cement (OPC). Although the CS were slightly declined at the elevated temperature, these proposed mix designs have a high potential for a wide variety of concrete industrial applications, especially in acid and sulphate risk.

Matched MeSH terms: Rubber
Characteristics and performance of aerobic granular sludge treating rubber wastewater at different hydraulic retention time

Rosman NH, Nor Anuar A, Chelliapan S, Md Din MF, Ujang Z

Bioresour Technol, 2014 Jun;161:155-61.
PMID: 24704837 DOI: 10.1016/j.biortech.2014.03.047

The influence of hydraulic retention time (HRT, 24, 12, and 6h) on the physical characteristics of granules and performance of a sequencing batch reactor (SBR) treating rubber wastewater was investigated. Results showed larger granular sludge formation at HRT of 6h with a mean size of 2.0±0.1mm, sludge volume index of 20.1mLg(-1), settling velocity of 61mh(-1), density of 78.2gL(-1) and integrity coefficient of 9.54. Scanning electron microscope analyses revealed different morphology of microorganisms and structural features of granules when operated at various HRT. The results also demonstrated that up to 98.4% COD reduction was achieved when the reactor was operated at low HRT (6h). Around 92.7% and 89.5% removal efficiency was noted for ammonia and total nitrogen in the granular SBR system during the treatment of rubber wastewater.

Matched MeSH terms: Rubber
Fulltext Studies on Leaf Venation in Selected Taxa of the Genus Ficus L. (Moraceae) in Peninsular Malaysia

Badron UH, Talip N, Mohamad AL, Affenddi AE, Juhari AA

Trop Life Sci Res, 2014 Dec;25(2):111-25.
PMID: 27073603 MyJurnal

A study on the variation of leaf venation patterns was conducted on 21 taxa of the genus Ficus in Peninsular Malaysia. The results showed the existence of eight leaf venation patterns based on veinlets, the ultimate marginal and areolar venation. The majority of species, such as F. annulata, F. benghalensis, F. benjamina, F. deltoidea var. angustifolia, F. deltoidea var. kunstleri, F. depressa, F. elastica, F. hispida, F. microcarpa, F. religiosa, F. tinctoria, F. ucinata and F. vasculosa, show tri-veinlets. The others exhibit the following: bi-veinlets in F. aurata and F. heteropleura; uni-veinlets in F. lepicarpa, F. schwarzii and F. superba; and simple veinlets in F. aurantiacea and F. fulva. F. sagittata presents no veinlets for areolar venation. The presence of tracheid or swollen veins at the centre of the lamina and the presence of cystolith cells and trichomes are common anatomical characteristics that could assist in group classification of the studied species. Variations in leaf venation patterns are not only valuable in identifying a taxon group, but can also be used to differentiate between species in the genus Ficus.

Matched MeSH terms: Rubber
Precipitation of Hevea brasiliensis latex proteins with trichloroacetic acid and phosphotungstic acid in preparation for the Lowry protein assay

Yeang HY, Yusof F, Abdullah L

Anal Biochem, 1995 Mar 20;226(1):35-43.
PMID: 7785777

Many proteins derived from the latex of Hevea brasiliensis that remain soluble in trichloroacetic acid (TCA) can be precipitated by phosphotungstic acid (PTA). A combination of 5% TCA and 0.2% PTA precipitates a wide range of proteins effectively even when they are present in low concentrations (below 1 microgram ml-1). In addition to its protein purification function, acid precipitation also increases the sensitivity of the subsequent protein assay by allowing the test sample to be concentrated. Another advantage of protein precipitation by TCA and PTA is that very small amounts of protein (of the order of 10 micrograms) can be repeatably recovered without the use of precipitate-bulking agents such as sodium deoxycholate. This general procedure of protein purification and concentration is simple and rapid, but the use of PTA may not be fully compatible with the Bradford protein assay. A modified Lowry microassay is described which enables about 3 micrograms ml-1 to be quantitated at the photometric absorbance of 0.05. When used in conjunction with protein concentration by precipitating with TCA/PTA, approximately 0.4 microgram ml-1 protein present in 6 ml of solution can be assayed.

Matched MeSH terms: Rubber/analysis
Fulltext A practical model for endodontic radiography teaching

Che Ab Aziz, Z.A.

Ann Dent, 2008;15(2):67-70.
MyJurnal

Aim: To manufacture a clinical simulation apparatus for the undergraduates' endodontic radiography teaching Objectives: • To provide a model for teaching of parallax method using Kelly's forcep • To provide a model for undergraduates to practice radiographic localization employing parallax method. • To allow students to practice taking radiographs in a way that simulates the clinical situations with a good diagnostic quality Methods: Impressions of a dentate arch (maxillary and mandibullary) were used to form a stone cast. A section of the cast, in the area where the natural teeth were to be placed, is sectioned and removed. Three maxillary extracted teeth (canine, first and second premolar) were selected and mounted with acrylic resin at the sectioned area. The resin was cured in a light box. The arches were mounted in a phantom head with a placement of rubber cheek. The first premolar was isolated with rubber dam. The intraoral holder (Kelly's forcep) was attached to a robotic arm. The students were taught the correct angulations of the x-ray cone for the paralleling technique and parallax method using Kelly's forcep during root canal treatment. Results: All students managed to complete the exercise and were considered competent when they produced acceptable quality of radiographs. Conclusion: The model described was improvised from a model that has been used during the past 2 years for undergraduates' endodontic courses. It has been well accepted as it simulates the clinical situation more closely than was possible previously.

Matched MeSH terms: Rubber; Rubber Dams
Fulltext Engineering characterisation of epoxidized natural rubber-modified hot-mix asphalt

Al-Mansob RA, Ismail A, Yusoff NI, Rahmat RA, Borhan MN, Albrka SI, et al.

PLoS One, 2017;12(2):e0171648.
PMID: 28182724 DOI: 10.1371/journal.pone.0171648

Road distress results in high maintenance costs. However, increased understandings of asphalt behaviour and properties coupled with technological developments have allowed paving technologists to examine the benefits of introducing additives and modifiers. As a result, polymers have become extremely popular as modifiers to improve the performance of the asphalt mix. This study investigates the performance characteristics of epoxidized natural rubber (ENR)-modified hot-mix asphalt. Tests were conducted using ENR-asphalt mixes prepared using the wet process. Mechanical testing on the ENR-asphalt mixes showed that the resilient modulus of the mixes was greatly affected by testing temperature and frequency. On the other hand, although rutting performance decreased at high temperatures because of the increased elasticity of the ENR-asphalt mixes, fatigue performance improved at intermediate temperatures as compared to the base mix. However, durability tests indicated that the ENR-asphalt mixes were slightly susceptible to the presence of moisture. In conclusion, the performance of asphalt pavement can be enhanced by incorporating ENR as a modifier to counter major road distress.

Matched MeSH terms: Rubber/chemistry*
Fulltext Large-scale collection of full-length cDNA and transcriptome analysis in Hevea brasiliensis

Makita Y, Ng KK, Veera Singham G, Kawashima M, Hirakawa H, Sato S, et al.

DNA Res, 2017 Apr 01;24(2):159-167.
PMID: 28431015 DOI: 10.1093/dnares/dsw056

Natural rubber has unique physical properties that cannot be replaced by products from other latex-producing plants or petrochemically produced synthetic rubbers. Rubber from Hevea brasiliensis is the main commercial source for this natural rubber that has a cis-polyisoprene configuration. For sustainable production of enough rubber to meet demand elucidation of the molecular mechanisms involved in the production of latex is vital. To this end, we firstly constructed rubber full-length cDNA libraries of RRIM 600 cultivar and sequenced around 20,000 clones by the Sanger method and over 15,000 contigs by Illumina sequencer. With these data, we updated around 5,500 gene structures and newly annotated around 9,500 transcription start sites. Second, to elucidate the rubber biosynthetic pathways and their transcriptional regulation, we carried out tissue- and cultivar-specific RNA-Seq analysis. By using our recently published genome sequence, we confirmed the expression patterns of the rubber biosynthetic genes. Our data suggest that the cytoplasmic mevalonate (MVA) pathway is the main route for isoprenoid biosynthesis in latex production. In addition to the well-studied polymerization factors, we suggest that rubber elongation factor 8 (REF8) is a candidate factor in cis-polyisoprene biosynthesis. We have also identified 39 transcription factors that may be key regulators in latex production. Expression profile analysis using two additional cultivars, RRIM 901 and PB 350, via an RNA-Seq approach revealed possible expression differences between a high latex-yielding cultivar and a disease-resistant cultivar.

Matched MeSH terms: Rubber/metabolism*
Liquefaction of kenaf (Hibiscus cannabinus L.) core for wood laminating adhesive

Juhaida MF, Paridah MT, Mohd Hilmi M, Sarani Z, Jalaluddin H, Mohamad Zaki AR

Bioresour Technol, 2010 Feb;101(4):1355-60.
PMID: 19833509 DOI: 10.1016/j.biortech.2009.09.048

A study was carried out to produce polyurethane (PU) as a wood laminating adhesive from liquefied kenaf core (LKC) polyols by reacting it with toluene-2,4-diisocyanate (TDI) and 1,4-butanediol (BDO). The LKC polyurethane (LKCPU) adhesive has a molecular weight (MW) of 2666, viscosity of 5370 mPa s, and solids content of 86.9%. The average shear strength of the rubberwood (RW) bonded with LKCPU adhesive was 2.9 MPa. Most of the sheared specimens experienced a total adhesive failure. The formation of air bubbles through the liberation of carbon dioxide was observed to reduce the adhesive penetration and bonding strength which was obviously seen on the sheared specimens. The percentage of catalyst used can be varied based on the usage and working time needed. Nonetheless, the physical properties of LKCPU produced in this work had shown good potential as edge-bonding adhesive.

Matched MeSH terms: Rubber/chemistry
Optimization study of ethanolic fermentation from oil palm trunk, rubberwood and mixed hardwood hydrolysates using Saccharomyces cerevisiae

Chin KL, H'ng PS, Wong LJ, Tey BT, Paridah MT

Bioresour Technol, 2010 May;101(9):3287-91.
PMID: 20056407 DOI: 10.1016/j.biortech.2009.12.036

Ethanolic fermentation using Saccharomyces cerevisiae was carried out on three types of hydrolysates produced from lignocelulosic biomass which are commonly found in Malaysia such as oil palm trunk, rubberwood and mixed hardwood. The effect of fermentation temperature and pH of hydrolysate was evaluated to optimize the fermentation efficiency which defined as maximum ethanol yield in minimum fermentation time. The fermentation process using different temperature of 25 degrees Celsius, 30 degrees Celsius and 40 degrees Celsius were performed on the prepared fermentation medium adjusted to pH 4, pH 6 and pH 7, respectively. Results showed that the fermentation time was significantly reduced with the increase of temperature but an adverse reduction in ethanol yield was observed using temperature of 40 degrees Celsius. As the pH of hydrolysate became more acidic, the ethanol yield increased. Optimum fermentation efficiency for ethanolic fermentation of lignocellulosic hydrolysates using S. cerevisiae can be obtained using 33.2 degrees Celsius and pH 5.3.

Matched MeSH terms: Rubber/metabolism*
FTIR spectra of plasticized grafted natural rubber-LiCF3SO3 electrolytes

Kumutha K, Alias Y

Spectrochim Acta A Mol Biomol Spectrosc, 2006 May 15;64(2):442-7.
PMID: 16530471

Chemical modification of natural rubber (NR) has frequently been attempted to improve the performance in specific application. 30% poly(methyl metacrylate) (PMMA) grafted into NR (MG30) has been explored as a potential candidate for polymer electrolytes. The complexation effect of salt and plasticizer in polymer host electrolytes had been investigated using FTIR. The carbonyl stretch of MG30 locates at 1729 cm-1, with the addition of lithium trimethanesulfonate (LiCF3SO3) salt, new band evolves at lower frequency region at 1643-1645 cm-1. The nondegenerate vibrational mode of nus(SO3) of salted electrolytes appearing at 1031-1034 cm-1 comes from 'free' trimethanesulfonate anions and the 1040-1046 cm-1 absorption from the monodentate ion paired with triflates. These indicate MG30-salt interaction. When MG30 and ethylene carbonate (EC) formed film, the CH3 asymmetric bend of MG30 appearing at 1447cm-1 is shifted to 1449 cm-1 in the EC-polymer complex. The CO stretching at 1729 cm-1 also shifted to 1728 cm-1. Hence, the EC-MG30 system is complexed to each other. EC-LiCF3SO3 interactions are indicated by the shifting of CO bending band of EC from 718 cm-1 being shifted to 720 cm-1 in the complex. In Li+-EC interaction where the ring breathing region at 897 cm-1 in EC has shifted to 899 cm-1 in EC-salt spectrum. The band appearing at 1643-1645 cm-1 due to the coordination of Li+

Matched MeSH terms: Rubber/chemistry*
Upgrading producer gas quality from rubber wood gasification in a radio frequency tar thermocatalytic treatment reactor

Anis S, Zainal ZA

Bioresour Technol, 2013 Dec;150:328-37.
PMID: 24185417 DOI: 10.1016/j.biortech.2013.10.010

This study focused on improving the producer gas quality using radio frequency (RF) tar thermocatalytic treatment reactor. The producer gas containing tar, particles and water was directly passed at a particular flow rate into the RF reactor at various temperatures for catalytic and thermal treatments. Thermal treatment generates higher heating value of 5.76 MJ Nm(-3) at 1200°C. Catalytic treatments using both dolomite and Y-zeolite provide high tar and particles conversion efficiencies of about 97% on average. The result also showed that light poly-aromatic hydrocarbons especially naphthalene and aromatic compounds particularly benzene and toluene were still found even at higher reaction temperatures. Low energy intensive RF tar thermocatalytic treatment was found to be effective for upgrading the producer gas quality to meet the end user requirements and increasing its energy content.

Matched MeSH terms: Rubber/chemistry*

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