MyMedR

Displaying all 12 publications

Abstract:

Sort:

Fulltext 4E analysis of a two-stage refrigeration system through surrogate models based on response surface methods and hybrid grey wolf optimizer

Ahmed R, Mahadzir S, Mota-Babiloni A, Al-Amin M, Usmani AY, Ashraf Rana Z, et al.

PLoS One, 2023;18(2):e0272160.
PMID: 36735732 DOI: 10.1371/journal.pone.0272160

Refrigeration systems are complex, non-linear, multi-modal, and multi-dimensional. However, traditional methods are based on a trial and error process to optimize these systems, and a global optimum operating point cannot be guaranteed. Therefore, this work aims to study a two-stage vapor compression refrigeration system (VCRS) through a novel and robust hybrid multi-objective grey wolf optimizer (HMOGWO) algorithm. The system is modeled using response surface methods (RSM) to investigate the impacts of design variables on the set responses. Firstly, the interaction between the system components and their cycle behavior is analyzed by building four surrogate models using RSM. The model fit statistics indicate that they are statistically significant and agree with the design data. Three conflicting scenarios in bi-objective optimization are built focusing on the overall system following the Technique for Order of Preference by Similarity to Ideal Solution (TOPSIS) and Linear Programming Technique for Multidimensional Analysis of Preference (LINMAP) decision-making methods. The optimal solutions indicate that for the first to third scenarios, the exergetic efficiency (EE) and capital expenditure (CAPEX) are optimized by 33.4% and 7.5%, and the EE and operational expenditure (OPEX) are improved by 27.4% and 19.0%. The EE and global warming potential (GWP) are also optimized by 27.2% and 19.1%, where the proposed HMOGWO outperforms the MOGWO and NSGA-II. Finally, the K-means clustering technique is applied for Pareto characterization. Based on the research outcomes, the combined RSM and HMOGWO techniques have proved an excellent solution to simulate and optimize two-stage VCRS.

Matched MeSH terms: Refrigeration*
Comparison of two newly suggested power, refrigeration, and hydrogen production, for moving towards sustainability schemes using improved solar-powered evolutionary algorithm optimization

Hai T, Abd El-Salam NM, Kh TI, Chaturvedi R, El-Shafai W, Farhang B

Chemosphere, 2023 Sep;336:139160.
PMID: 37327820 DOI: 10.1016/j.chemosphere.2023.139160

In the third millennium, developing countries will confront significant environmental problems such as ozone depletion, global warming, the shortage of fossil resources, and greenhouse gas emissions. This research looked at a multigenerational system that can generate clean hydrogen, fresh water, electricity, heat, and cooling. The system's components include Rankine and Brayton cycles, an Organic Rankine Cycle (ORC), flash desalination, an Alkaline electrolyzer, and a solar heliostat. The proposed process has been compared for two different start-up modes with a combustion chamber and solar heliostat to compare renewable and fossil fuel sources. This research evaluated various characteristics, including turbine pressure, system efficiency, solar radiation, and isentropic efficiency. The energy and exergy efficiency of the proposed system were obtained at around 78.93% and 47.56%, respectively. Exergy study revealed that heat exchangers and alkaline electrolyzers had the greatest exergy destruction rates, at 78.93% and 47.56%, respectively. The suggested system produces 0.04663 kg/s of hydrogen. Results indicate that at the best operational conditions, the exergetic efficiency, power, and hydrogen generation of 56%, 6000 kW, and 1.28 kg/s is reached, respectively. Also, With a 15% improvement in the Brayton cycle's isentropic efficacy, the quantity of hydrogen produced increases from 0.040 kg/s to 0.0520 kg/s.

Matched MeSH terms: Refrigeration*
Fulltext A scaling law for distinct electrocaloric cooling performance in low-dimensional organic, relaxor and anti-ferroelectrics

Shi Y, Huang L, Soh AK, Weng GJ, Liu S, Redfern SAT

Sci Rep, 2017 09 11;7(1):11111.
PMID: 28894256 DOI: 10.1038/s41598-017-11633-y

Electrocaloric (EC) materials show promise in eco-friendly solid-state refrigeration and integrable on-chip thermal management. While direct measurement of EC thin-films still remains challenging, a generic theoretical framework for quantifying the cooling properties of rich EC materials including normal-, relaxor-, organic- and anti-ferroelectrics is imperative for exploiting new flexible and room-temperature cooling alternatives. Here, we present a versatile theory that combines Master equation with Maxwell relations and analytically relates the macroscopic cooling responses in EC materials with the intrinsic diffuseness of phase transitions and correlation characteristics. Under increased electric fields, both EC entropy and adiabatic temperature changes increase quadratically initially, followed by further linear growth and eventual gradual saturation. The upper bound of entropy change (∆Smax) is limited by distinct correlation volumes (V cr ) and transition diffuseness. The linearity between V cr and the transition diffuseness is emphasized, while ∆Smax = 300 kJ/(K.m3) is obtained for Pb0.8Ba0.2ZrO3. The ∆Smax in antiferroelectric Pb0.95Zr0.05TiO3, Pb0.8Ba0.2ZrO3 and polymeric ferroelectrics scales proportionally with V cr-2.2, owing to the one-dimensional structural constraint on lattice-scale depolarization dynamics; whereas ∆Smax in relaxor and normal ferroelectrics scales as ∆Smax ~ V cr-0.37, which tallies with a dipolar interaction exponent of 2/3 in EC materials and the well-proven fractional dimensionality of 2.5 for ferroelectric domain walls.

Matched MeSH terms: Refrigeration
Growth of Chrysomya megacephala (Fabricius) maggots in a morgue cooler

Thevan K, Ahmad AH, Rawi CS, Singh B

J Forensic Sci, 2010 Nov;55(6):1656-8.
PMID: 20579228 DOI: 10.1111/j.1556-4029.2010.01485.x

In estimating the postmortem interval (PMI) using maggots obtained during autopsy, the forensic entomologist makes decisions regarding the effects of low-temperature storage of the body on the insects. In this case report, a corpse was found in an abandoned house in the residential area of Bukit Mertajam, Penang, Malaysia. The maggots were found to be alive inside the mouth of the deceased although the corpse had been in the morgue cooler for 12 days. The maggots were reared and identified as Chrysomya megacephala (Fabricius). The emerged adult flies were kept as a stock colony, and the duration of development under the indoor fluctuating temperature regime was studied. The total duration of developmental process of this species was 9.5 ± 0.5 days, and the PMI estimated was 3.2 ± 0.6 days. This case report demonstrates the survival of Ch. megacephala maggots for 12 days and their growth inside the morgue cooler.

Matched MeSH terms: Refrigeration*
Growth of Bifidobacterium longum BB536 in medida (fermented cereal porridge) and their survival during refrigerated storage

Kabeir BM, Abd-Aziz S, Muhammad K, Shuhaimi M, Yazid AM

Lett Appl Microbiol, 2005;41(2):125-31.
PMID: 16033508

To develop medida, a Sudanese fermented thin porridge as a probiotic dietary adjunct with high total solids.

Matched MeSH terms: Refrigeration*
Fulltext Immunogenicity and protective efficacy of a live, oral cholera vaccine formulation stored outside-the-cold-chain for 140 days

Xian TH, Sinniah K, Yean CY, Krishnamoorthy V, Bahari MB, Ravichandran M, et al.

BMC Immunol, 2020 05 25;21(1):29.
PMID: 32450807 DOI: 10.1186/s12865-020-00360-1

BACKGROUND: Cholera, an acute watery diarrhoeal disease caused by Vibrio cholerae serogroup O1 and O139 across the continents. Replacing the existing WHO licensed killed multiple-dose oral cholera vaccines that demand 'cold chain supply' at 2-8 °C with a live, single-dose and cold chain-free vaccine would relieve the significant bottlenecks and cost determinants in cholera vaccination campaigns. In this direction, a prototype cold chain-free live attenuated cholera vaccine formulation (LACV) was developed against the toxigenic wild-type (WT) V. cholerae O139 serogroup. LACV was found stable and retained its viability (5 × 106 CFU/mL), purity and potency at room temperature (25 °C ± 2 °C, and 60% ± 5% relative humidity) for 140 days in contrast to all the existing WHO licensed cold-chain supply (2-8 °C) dependent killed oral cholera vaccines.
RESULTS: The LACV was evaluated for its colonization potential, reactogenicity, immunogenicity and protective efficacy in animal models after its storage at room temperature for 140 days. In suckling mice colonization assay, the LACV recorded the highest recovery of (7.2 × 107 CFU/mL) compared to those of unformulated VCUSM14P (5.6 × 107 CFU/mL) and the WT O139 strain (3.5 × 107 CFU/mL). The LACV showed no reactogenicity even at an inoculation dose of 104-106 CFU/mL in a rabbit ileal loop model. The rabbits vaccinated with the LACV or unformulated VCUSM14P survived a challenge with WT O139 and showed no signs of diarrhoea or death in the reversible intestinal tie adult rabbit diarrhoea (RITARD) model. Vaccinated rabbits recorded a 275-fold increase in anti-CT IgG and a 15-fold increase in anti-CT IgA antibodies compared to those of rabbits vaccinated with unformulated VCUSM14P. Vibriocidal antibodies were increased by 31-fold with the LACV and 14-fold with unformulated VCUSM14P.
CONCLUSION: The vaccine formulation mimics a natural infection, is non-reactogenic and highly immunogenic in vivo and protects animals from lethal wild-type V. cholerae O139 challenge. The single dose LACV formulation was found to be stable at room temperature (25 ± 2 °C) for 140 days and it would result in significant cost savings during mass cholera vaccination campaigns.

Matched MeSH terms: Refrigeration/methods
Fulltext Knowledge on immunisation among nurses in Malaysia

Lidwina Edwin Amir

Malaysian Journal of Medicine and Health Sciences, 2019;15(104):21-21.
MyJurnal

Introduction: The National Immunization Program in Malaysia began in the 1950s and was integrated into the Ma-ternal and Child Health Program. Administrative data showed that coverage for all vaccinations was more than 95% except for measles vaccination. Despite the high coverage, there were clusters of outbreaks of vaccine preventable diseases. One of the reasons is the increasing phenomena of vaccines refusals following the rapid spread of negative perception and concerns through social media. Nurses as front liners play an important role to communicate on vac-cine safety and adverse events (AEFI). A survey was conducted to identify the level of knowledge among nurses who deal with immunisation programme. Methods: Nurses from all states attending a National seminar on immunisation communication in Putrajaya were asked to answer a Digital online questionnaire. They were asked to answer 12 questions on knowledge of vaccines, immunization schedule and cold chain management. Results: A total of 74% (429) of the seminar participants responded to the questionnaire, of which 85% were from the government sector and 15% from private. Findings showed that although about 75% of the nurses had formal training on immunisation, 50% had lack of knowledge about vaccination schedule for defaulters and 63.2% (268) had knowledge gaps related to questions on vaccines and handling of vaccines. Conclusion: In view of the knowledge gap from this survey, there is a need for ongoing training for the nurses and evaluation by supervisors on the knowledge and practices among nurses.

Matched MeSH terms: Refrigeration
Viability and activity of bifidobacteria during refrigerated storage of yoghurt containing Mangifera pajang fibrous polysaccharides

Al-Sheraji SH, Ismail A, Manap MY, Mustafa S, Yusof RM

J Food Sci, 2012 Nov;77(11):M624-30.
PMID: 23106104 DOI: 10.1111/j.1750-3841.2012.02955.x

The viability and activity of Bifidobacterium pseudocatenulatum G4, B. longum BB 536 and yoghurt cultures (Lactobacillus delbrueckii ssp. bulgaricus and Streptococcus thermophilus) were studied in yoghurt containing 0.75% Mangefira pajang fibrous polysaccharides (MPFP) and inulin. Growth of probiotic organisms, their proteolytic activities, the production of short chain fatty acids (lactic, acetic and propionic) and the pH of the yoghurt samples were determined during refrigerated storage at 4 °C for 28 d. B. pseudocatenulatum G4 and B. longum BB 536 showed better growth and activity in the presence of MPFP and inulin, which significantly increased the production of short chain fatty acids as well as the proteolytic activity of these organisms.

Matched MeSH terms: Refrigeration/methods
Development of a dry-reagent-based nucleic acid-sensing platform by coupling thermostabilised LATE-PCR assay to an oligonucleotide-modified lateral flow biosensor

Ang GY, Yu CY, Chan KG, Singh KK, Chan Yean Y

J Microbiol Methods, 2015 Nov;118:99-105.
PMID: 26342435 DOI: 10.1016/j.mimet.2015.08.024

In this study, we report for the first time the development of a dry-reagent-based nucleic acid-sensing platform by combining a thermostabilised linear-after-the-exponential (LATE)-PCR assay with a one-step, hybridisation-based nucleic acid lateral flow biosensor. The nucleic acid-sensing platform was designed to overcome the need for stringent temperature control during transportation or storage of reagents and reduces the dependency on skilled personnel by decreasing the overall assay complexity and hands-on time. The platform was developed using toxigenic Vibrio cholerae as the model organism due to the bacterium's propensity to cause epidemic and pandemic cholera. The biosensor generates result which can be visualised with the naked eyes and the limit of detection was found to be 1pg of pure genomic DNA and 10CFU/ml of toxigenic V. cholerae. The dry-reagent-based nucleic acid-sensing platform was challenged with 95 toxigenic V. cholerae, 7 non-toxigenic V. cholerae and 66 other bacterial strains in spiked stool sample and complete agreement was observed when the results were compared to that of monosialoganglioside (GM1)-ELISA. Heat-stability of the thermostabilised LATE-PCR reaction mixes at different storage temperatures (4-56°C) was investigated for up to 90days. The dry-reagent-based genosensing platform with ready-to-use assay components provides an alternative method for sequence-specific detection of nucleic acid without any cold chain restriction that is associated with conventional molecular amplification techniques.

Matched MeSH terms: Refrigeration
A prospective study of mycobacterial viability in refrigerated, unpreserved sputum batched for up to 8 weeks

Rashid Ali MR, Parameswaran U, William T, Bird E, Wilkes CS, Lee WK, et al.

Int J Tuberc Lung Dis, 2015 May;19(5):620-1.
PMID: 25868033 DOI: 10.5588/ijtld.14.0938
Matched MeSH terms: Refrigeration
Fulltext Recovery of poliovirus from cut surface of stored fresh papaya fruit

Lee ASC, Yap KL

Southeast Asian J. Trop. Med. Public Health, 1999 Jun;30(2):280-3.
PMID: 10774695

Poliovirus kept on the cut surfaces of fully ripe papaya cubes placed in an ice box showed a sharp and significant reduction in the recovery of infectious virus about 15 minutes after exposure. Thereafter, a very gradual decrease ensued and infectious residual virus was detected up to the end of the 6-hour exposure period. Papaya cubes washed or kept overnight before virus inoculation, and from less ripe fruits produced a similar survival pattern. A very small proportion of the inoculum was recovered from the mashed content of the inoculated papaya cubes thus suggesting that most of the non-recovered virus particles were inactivated. The results suggest that the importance of poliovirus-contaminated cut papayas as a transmission vehicle for the virus is greatly reduced by the rapid decline in the infectivity of a large proportion of the virus soon after contamination. Nevertheless, the potential to transmit remains as a small residual pool of infectious poliovirus is able to survive for a relatively long period.

Matched MeSH terms: Refrigeration
Repeated dose toxicity evaluation of a cold chain-free, live, attenuated oral cholera vaccine in Sprague Dawley rats

Xian TH, Parasuraman S, Sinniah K, Ravichandran M, Prabhakaran G

Vaccine, 2019 01 29;37(5):711-720.
PMID: 30630696 DOI: 10.1016/j.vaccine.2018.12.027

The repeated dose toxicity of a prototype cold chain-free, live, attenuated oral cholera vaccine containing 5 × 106 CFU/mL of the VCUSM14P strain was evaluated in Sprague Dawley (SD) rats (single dose administered daily for 30 days) to ascertain its safety for clinical use. Repeated dose toxicity studies for cholera vaccines in the literature have administered 2 or 3 fixed doses at 7, 14, 21 or 69 day intervals. The present study reports an evaluation of 30 repeated doses of cholera vaccine administered at three different concentrations (Group II (1.25 × 106 CFU), Group III (2.5 × 106 CFU) and Group IV (5 × 106 CFU)) in SD rats. The liquid vaccine was administered orally to the rats with the respective dose every day, and normal saline was administered to the control group (Group I). No significant difference (P > 0.05) was observed in the body weights and biochemical parameters of the rats after 15 and 30 repeated doses compared to those of the control group. However, compared to those of Group I, a significant increase (P 

Matched MeSH terms: Refrigeration

Filters

Please provide feedback to Administrator (afdal@afpm.org.my)

External Links