MyMedR

Displaying all 8 publications

Abstract:

Sort:

Sequential ultrasound-microwave assisted acid extraction (UMAE) of pectin from pomelo peels

Liew SQ, Ngoh GC, Yusoff R, Teoh WH

Int J Biol Macromol, 2016 Dec;93(Pt A):426-435.
PMID: 27565298 DOI: 10.1016/j.ijbiomac.2016.08.065

This study aims to optimize sequential ultrasound-microwave assisted extraction (UMAE) on pomelo peel using citric acid. The effects of pH, sonication time, microwave power and irradiation time on the yield and the degree of esterification (DE) of pectin were investigated. Under optimized conditions of pH 1.80, 27.52min sonication followed by 6.40min microwave irradiation at 643.44W, the yield and the DE value of pectin obtained was respectively at 38.00% and 56.88%. Based upon optimized UMAE condition, the pectin from microwave-ultrasound assisted extraction (MUAE), ultrasound assisted extraction (UAE) and microwave assisted extraction (MAE) were studied. The yield of pectin adopting the UMAE was higher than all other techniques in the order of UMAE>MUAE>MAE>UAE. The pectin's galacturonic acid content obtained from combined extraction technique is higher than that obtained from sole extraction technique and the pectin gel produced from various techniques exhibited a pseudoplastic behaviour. The morphological structures of pectin extracted from MUAE and MAE closely resemble each other. The extracted pectin from UMAE with smaller and more regular surface differs greatly from that of UAE. This has substantiated the highest pectin yield of 36.33% from UMAE and further signified their compatibility and potentiality in pectin extraction.
Fulltext Effect of single-dose dexmedetomidine on postoperative recovery after ambulatory ureteroscopy and ureteric stenting: a double blind randomized controlled study

Shariffuddin II, Teoh WH, Wahab S, Wang CY

BMC Anesthesiol, 2018 01 05;18(1):3.
PMID: 29304735 DOI: 10.1186/s12871-017-0464-6

BACKGROUND: Ambulatory surgery has recently gain popularity, as it is a good method of optimizinghospital resources utilization. To support ambulatory surgery, anaesthetic goals nowrevolve around patients' early recovery with minimal pain and nausea, expedientdischarge home and prompt resumption of activities of daily living. In this study, weevaluated the effect of a single pre-induction dose of dexmedetomidine on anaestheticrequirements, postoperative pain and clinical recovery after ambulatory ureteroscopy andureteric stenting under general anaesthesia.
METHODS: Sixty patients were randomised to receive IV dexmedetomidine 0.5 μg.kg-1 (Group DEX, n = 30) or IV saline (Group P, n = 30). General anaesthesia was maintained with Sevoflurane: oxygen: air, titrated to BIS 40-60. Pain intensity, sedation, rescue analgesics, nausea/vomiting and resumption of daily activities were recorded at 1 h, and postoperative day (POD) 1-5.
RESULTS: Group DEX patients had significant reduction in sevoflurane minimum alveolar concentration (MAC), mean (SD) DEX vs. Placebo 0.6 (0.2) vs. 0.9 (0.1), p = 0.037; reduced postoperative resting pain at 1 h (VAS 0-10) (mean (SD) 1.00 (1.84) vs. 2.63 (2.78), p = 0.004), POD 1 (mean (SD) 1.50 (1.48) vs. 2.87 (2.72), p = 0.002), POD 2 (0.53 (0.97) vs. 1.73 (1.96), p = 0.001) and POD 3 (0.30 (0.75) vs. 0.89 (1.49), p = 0.001). DEX patients also had less pain on movement POD 1 (3.00 (2.12) vs. 4.30 (3.10), p = 0.043) and POD 2 (2.10 (1.98) vs. 3.10 (2.46), p = 0.040), with higher resumption of daily activities by 48 h compared to placebo, 87% vs. 63%, p = 0.04.
CONCLUSIONS: We conclude that a single dose of dexmedetomidine was a useful adjuvant in reducing MAC and postoperative pain (at 1 h and POD 1-3), facilitating faster return to daily activities by 48 h.
TRIAL REGISTRATION: The Australian New Zealand Clinical Trials Registry (ANZCTR), ACTRN12617001120369 , 31st July 2017, retrospectively registered.
Fulltext Rutin extraction from female Carica papaya Linn. using ultrasound and microwave-assisted extractive methods: Optimization and extraction efficiencies

Chew SK, Teoh WH, Hong SL, Yusoff R

Heliyon, 2023 Oct;9(10):e20260.
PMID: 37810831 DOI: 10.1016/j.heliyon.2023.e20260

Green extractive methods accompanied by resource conservation through process optimization are important in working towards sustainable processes. In the present paper, rutin was extracted from the leaf of female Carica papaya Linn using microwave-assisted extraction (MAE), ultrasound-assisted extraction (UAE), sequential microwave ultrasound-assisted extraction (MUAE), and sequential ultrasound microwave-assisted extraction (UMAE) methods. Subsequently, the effect of extraction parameters on rutin yield were analyzed and compared. In addition, the extraction efficiency and energy consumption of the extraction processes were measured and discussed. In the present study, solid-liquid (S/L) ratio was determined to be the most significant extraction variable. Under optimized conditions, MUAE and UMAE were determined to yield the highest amount of rutin extracted at 18.46 ± 0.64 mg/g and 18.43 ± 0.81 mg/g, respectively. However, MUAE was determined to be the least resource efficient method as it consumed the highest amount of energy due to its relatively long extraction time. UAE was determined to be the most efficient in resource utilization as it required the least amount of energy for every mg/g of yield extracted, while the yield obtained was, nonetheless, comparatively high. The optimal condition obtained for UAE was 20 min of ultrasonic extraction time (TU), 20 % of ethanol mixture concentration (C), 710 μm of particle size (S), and 1:650 wt/wt of solid-liquid (S/L) ratio (R).
Ambu® AuraGain™ versus LMA Supreme™ Second Seal™: a randomised controlled trial comparing oropharyngeal leak pressures and gastric drain functionality in spontaneously breathing patients

Shariffuddin II, Teoh WH, Tang E, Hashim N, Loh PS

Anaesth Intensive Care, 2017 03;45(2):244-250.
PMID: 28267947 DOI: 10.1177/0310057X1704500215

Newer second generation supraglottic airway devices may perform differently in vivo due to material and design modifications. We compared performance characteristics of the Ambu® AuraGain™ and LMA Supreme™ Second Seal™ in 100 spontaneously breathing anaesthetised patients in this randomised controlled study. We studied oropharyngeal leak pressures (OLP) (primary outcome) and secondarily, ease of insertion, success rates, haemodynamic response, time to insertion, and complications of usage. We found no significant difference in OLP between the AuraGain versus the LMA Supreme, mean (standard deviation, SD) 24.1 (7.4) versus 23.6 (6.2) cmH2O, P=0.720. First-attempt placement rates of the AuraGain were comparable to the LMA Supreme, 43/50 (86%) versus 39/50 (78%), P=0.906, with an overall 98% insertion success rate for the AuraGain and 88% for the LMA Supreme after three attempts, P=0.112. However, the AuraGain was deemed subjectively harder to insert, with only 24/50 (48%) versus 37/50 (74%) of AuraGain insertions being scored 1 = easy (on a 5 point scale), P=0.013, and also took longer to insert, 33.4 (SD 10.9) versus 27.3 (SD 11.4) seconds, P=0.010. The AuraGain needed a smaller volume of air (16.4 [SD 6.8] versus 23.0 [SD 7.4] ml, P <0.001) to attain intracuff pressures of 60 cmH2O, facilitated more successful gastric tube insertion (100% versus 90.9%, P=0.046), and had significantly decreased sore throat incidence (10% versus 38%, P=0.020). One AuraGain and six LMA Supremes failed to be placed within the stipulated 120 seconds trial definition of 'success'; these patients had risk factors for failed supraglottic insertion. In conclusion, both devices had similar OLPs and performed satisfactorily. However, the AuraGain resulted in less postoperative sore throat despite being harder to and taking longer to, insert.
Subcritical water extraction of low methoxyl pectin from pomelo (Citrus grandis (L.) Osbeck) peels

Liew SQ, Teoh WH, Tan CK, Yusoff R, Ngoh GC

Int J Biol Macromol, 2018 Sep;116:128-135.
PMID: 29738869 DOI: 10.1016/j.ijbiomac.2018.05.013

Low methoxyl (LM) pectin was extracted from pomelo peels using subcritical water in a dynamic mode. The effects of pressure and temperature were analyzed through a face-centred central composite design. Extraction yield and the rate of extraction were found to be predominantly influenced by temperature. Optimization of the subcritical water extraction (SWE) yielded an optimized operating condition of 120°C and 30bar with a predicted pectin yield of 18.8%. The corresponding experimental yield was 19.6%, which is in close agreement with the predicted data. The pectin obtained from the optimized condition was further analyzed for its physicochemical properties. The kinetics of the SWE was also evaluated whereby the one-site kinetic desorption model was found to be in good agreement with experimental data (R2>0.94).
Recent Advances in the Application of Inorganic Salt Pretreatment for Transforming Lignocellulosic Biomass into Reducing Sugars

Loow YL, Wu TY, Tan KA, Lim YS, Siow LF, Jahim JM, et al.

J Agric Food Chem, 2015 Sep 30;63(38):8349-63.
PMID: 26325225 DOI: 10.1021/acs.jafc.5b01813

Currently, the transformation of lignocellulosic biomass into value-added products such as reducing sugars is garnering attention worldwide. However, efficient hydrolysis is usually hindered by the recalcitrant structure of the biomass. Many pretreatment technologies have been developed to overcome the recalcitrance of lignocellulose such that the components can be reutilized more effectively to enhance sugar recovery. Among all of the utilized pretreatment methods, inorganic salt pretreatment represents a more novel method and offers comparable sugar recovery with the potential for reducing costs. The use of inorganic salt also shows improved performance when it is integrated with other pretreatment technologies. Hence, this paper is aimed to provide a detailed overview of the current situation for lignocellulosic biomass and its physicochemical characteristics. Furthermore, this review discusses some recent studies using inorganic salt for pretreating biomass and the mechanisms involved during the process. Finally, some prospects and challenges using inorganic salt are highlighted.
Fulltext Clinical performance of the LMA Protector™ airway in moderately obese patients

Shariffuddin II, Chaw SH, Ng LW, Lim CH, Zainal Abidin MF, Wan Zakaria WA, et al.

BMC Anesthesiol, 2020 07 31;20(1):184.
PMID: 32736516 DOI: 10.1186/s12871-020-01100-z

BACKGROUND: The 4th National Audit Project of The Royal College of Anaesthetists and The Difficult Airway Society (NAP4) reported a higher incidence of supraglottic airway device (SAD) related pulmonary aspiration in obese patients especially with the first-generation SADs. The latest single-use SAD, the Protector™ provides a functional separation of the respiratory and digestive tracts and its laryngeal cuff with two ports allowing additional suction in tandem with the insertion of a gastric tube. The laryngeal cuff of LMA Protector™ allows a large catchment reservoir in the event of gastric content aspiration.
METHODS: We evaluated the performance characteristics of the LMA Protector™ in 30 unparalysed, moderately obese patients. First attempt insertion rate, time for insertion, oropharyngeal leak pressure (OLP), and incidence of complications were recorded.
RESULTS: We found high first and second attempt insertion rates of 28(93%) and 1(33%) respectively, with one failed attempt where no capnography trace could be detected, presumably from a downfolded device tip. The LMA Protector™ was inserted rapidly in 21.0(4.0) seconds and demonstrated high OLP of 31.8(5.4) cmH2O. Fibreoptic assessment showed a clear view of vocal cords in 93%. The incidence of blood staining on removal of device was 48%, postoperative sore throat 27%, dysphagia 10% and dysphonia 20% (all self-limiting, resolving a few hours postoperatively).
CONCLUSIONS: We conclude that the LMA Protector™ was associated with easy, expedient first attempt insertion success, demonstrating high oropharyngeal pressures and good anatomical position in the moderately obese population, with relatively low postoperative airway morbidity.
TRIAL REGISTRATION: Australian New Zealand Clinical Trials Registry, ACTRN12617001152314 . Registered 7 August 2017.
Deep eutectic solvent and inorganic salt pretreatment of lignocellulosic biomass for improving xylose recovery

Loow YL, Wu TY, Yang GH, Ang LY, New EK, Siow LF, et al.

Bioresour Technol, 2018 Feb;249:818-825.
PMID: 29136937 DOI: 10.1016/j.biortech.2017.07.165

Deep eutectic solvents (DESs) have received considerable attention in recent years due to their low cost, low toxicity, and biodegradable properties. In this study, a sequential pretreatment comprising of a DES (choline chloride:urea in a ratio of 1:2) and divalent inorganic salt (CuCl2) was evaluated, with the aim of recovering xylose from oil palm fronds (OPF). At a solid-to-liquid ratio of 1:10 (w/v), DES alone was ineffective in promoting xylose extraction from OPF. However, a combination of DES (120°C, 4h) and 0.4mol/L of CuCl2 (120°C, 30min) resulted in a pretreatment hydrolysate containing 14.76g/L of xylose, remarkably yielding 25% more xylose than the CuCl2-only pretreatment (11.87g/L). Characterization studies such as FE-SEM, BET, XRD, and FTIR confirmed the delignification of OPF when DES was implemented. Thus, the use of this integrated pretreatment system enabled xylose recoveries which were comparable with other traditional pretreatments.