Displaying publications 21 - 40 of 50 in total

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  1. Fernando HV, Chan LL, Dang N, Santhanes D, Banneheke H, Nalliah S, et al.
    Pharm Dev Technol, 2019 Mar;24(3):348-356.
    PMID: 29799300 DOI: 10.1080/10837450.2018.1481430
    Microporous polymeric matrices prepared from poly(ɛ-caprolactone) [PCL] were evaluated for controlled vaginal delivery of the antiprotozoal agent (tinidazole) in the treatment of the sexually transmitted infection, trichomoniasis. The matrices were produced by rapidly cooling co-solutions of PCL and tinidazole in acetone to -80 °C to induce crystallisation and hardening of the polymer. Tinidazole incorporation in the matrices increased from 1.4 to 3.9% (w/w), when the drug concentration in the starting PCL solution was raised from 10 to 20% (w/w), giving rise to drug loading efficiencies up to 20%. Rapid 'burst release' of 30% of the tinidazole content was recorded over 24 h when the PCL matrices were immersed in simulated vaginal fluid. Gradual drug release occurred over the next 6 days resulting in delivery of around 50% of the tinidazole load by day 7 with the released drug retaining antiprotozoal activity at levels almost 50% that of the 'non-formulated' drug in solution form. Basic modelling predicted that the concentration of tinidazole released into vaginal fluid in vivo from a PCL matrix in the form of an intravaginal ring would exceed the minimum inhibitory concentration against Trichomonas vaginalis. These findings recommend further investigation of PCL matrices as intravaginal devices for controlled delivery of antiprotozoal agents in the treatment and prevention of sexually transmitted infections.
  2. Tan XJ, Cheor WL, Lim LL, Ab Rahman KS, Bakrin IH
    Diagnostics (Basel), 2022 Dec 09;12(12).
    PMID: 36553119 DOI: 10.3390/diagnostics12123111
    Artificial intelligence (AI), a rousing advancement disrupting a wide spectrum of applications with remarkable betterment, has continued to gain momentum over the past decades. Within breast imaging, AI, especially machine learning and deep learning, honed with unlimited cross-data/case referencing, has found great utility encompassing four facets: screening and detection, diagnosis, disease monitoring, and data management as a whole. Over the years, breast cancer has been the apex of the cancer cumulative risk ranking for women across the six continents, existing in variegated forms and offering a complicated context in medical decisions. Realizing the ever-increasing demand for quality healthcare, contemporary AI has been envisioned to make great strides in clinical data management and perception, with the capability to detect indeterminate significance, predict prognostication, and correlate available data into a meaningful clinical endpoint. Here, the authors captured the review works over the past decades, focusing on AI in breast imaging, and systematized the included works into one usable document, which is termed an umbrella review. The present study aims to provide a panoramic view of how AI is poised to enhance breast imaging procedures. Evidence-based scientometric analysis was performed in accordance with the Preferred Reporting Items for Systematic reviews and Meta-Analyses (PRISMA) guideline, resulting in 71 included review works. This study aims to synthesize, collate, and correlate the included review works, thereby identifying the patterns, trends, quality, and types of the included works, captured by the structured search strategy. The present study is intended to serve as a "one-stop center" synthesis and provide a holistic bird's eye view to readers, ranging from newcomers to existing researchers and relevant stakeholders, on the topic of interest.
  3. Tan CS, Bandak DB, Habeebur-Rahman SP, Tan LT, Lim LLA
    Virol J, 2023 Aug 07;20(1):176.
    PMID: 37550752 DOI: 10.1186/s12985-023-02133-9
    SARS-CoV-2 is a zoonotic betacoronavirus that was first reported at the dawn of 2019 in Wuhan, China and has since spread globally, causing an ongoing pandemic. Anthroponotic transmission was reported early, with confirmed infections reported in 26 species to date, including dogs and cats. However, there is a paucity of reports on the transmission of SARS-CoV-2 to companion animals, and thus, we aimed to estimate the seroprevalence of SARS-CoV-2 in dogs and cats in Sarawak, Malaysia. From August 2022 to 2023, we screened plasma samples of 172 companion animals in Sarawak, Malaysia, using a species-independent surrogate virus neutralization test. Our findings revealed the presence of neutralizing antibodies of SARS-CoV-2 in 24.5% (27/110) of dogs and 24.2% (15/62) of cats. To the best of our knowledge, this is the first report of the seroprevalence of SARS-CoV-2 in companion animals in Malaysia. Our findings emphasize the need for pet owners to distance themselves from their pets when unwell, and a strategy must be in place to monitor SARS-CoV-2 in companion animals to assess the potential impact of the virus on companion animals.
  4. Tan T, Ong WS, Rajasekaran T, Nee Koo K, Chan LL, Poon D, et al.
    PLoS One, 2016;11(5):e0156008.
    PMID: 27231951 DOI: 10.1371/journal.pone.0156008
    PURPOSE: Elderly cancer patients are at increased risk for malnutrition. We aim to identify comprehensive geriatric assessment (CGA) based clinical factors associated with increased nutritional risk and develop a clinical scoring system to identify nutritional risk in elderly cancer patients.

    PATIENTS AND METHODS: CGA data was collected from 249 Asian patients aged 70 years or older. Nutritional risk was assessed based on the Nutrition Screening Initiative (NSI) checklist. Univariate and multivariate logistic regression analyses were applied to assess the association between patient clinical factors together with domains within the CGA and moderate to high nutritional risk. Goodness of fit was assessed using Hosmer-Lemeshow test. Discrimination ability was assessed based on the area under the receiver operating characteristics curve (AUC). Internal validation was performed using simulated datasets via bootstrapping.

    RESULTS: Among the 249 patients, 184 (74%) had moderate to high nutritional risk. Multivariate logistic regression analysis identified stage 3-4 disease (Odds Ratio [OR] 2.54; 95% CI, 1.14-5.69), ECOG performance status of 2-4 (OR 3.04; 95% CI, 1.57-5.88), presence of depression (OR 5.99; 95% CI, 1.99-18.02) and haemoglobin levels <12 g/dL (OR 3.00; 95% CI 1.54-5.84) as significant independent factors associated with moderate to high nutritional risk. The model achieved good calibration (Hosmer-Lemeshow test's p = 0.17) and discrimination (AUC = 0.80). It retained good calibration and discrimination (bias-corrected AUC = 0.79) under internal validation.

    CONCLUSION: Having advanced stage of cancer, poor performance status, depression and anaemia were found to be predictors of moderate to high nutritional risk. Early identification of patients with these risk factors will allow for nutritional interventions that may improve treatment tolerance, quality of life and survival outcomes.

  5. Yong YK, Wen NCM, Yeo GEC, Chew ZX, Chan LL, Md Zain NZ, et al.
    PMID: 34574752 DOI: 10.3390/ijerph18189828
    Several bacterial species cause post-operative infections, which has been a critical health concern among hospital patients. Our study in this direction is a much-needed exploratory study that was carried out at the National Heart Institute (IJN) of Malaysia to examine the virulence properties of causative bacteria obtained from postoperative patients. The bacterial isolates and data were provided by the IJN. Antibiotic resistance gene patterns, and the ability to form biofilm were investigated for 127 isolates. Klebsiella pneumoniae (36.2%) was the most common isolate collected, which was followed by Pseudomonas aeruginosa (26%), Staphylococcus aureus (23.6%), Streptococcus spp. (8.7%) and Acinetobacter baumannii (5.5%). There were 49 isolates that showed the presence of multidrug resistance genes. The mecA gene was surprisingly found in methicillin-susceptible S. aureus (MSSA), which also carried the ermA gene from those erythromycin-susceptible strains. The phenotypic antibiotic resistance profiles varied greatly between isolates. Findings from the biofilm assay revealed that 44 of the 127 isolates demonstrated the ability to produce biofilms. Our findings provide insights into the possibility of some of these bacteria surviving under antibiotic stress, and some antibiotic resistance genes being silenced.
  6. Chan LL, Toh HC, Jaikwang K, Loo EM, Wong JH, Liew YK, et al.
    Acta Trop, 2022 Feb 16.
    PMID: 35182491 DOI: 10.1016/j.actatropica.2022.106372
    Pathogenic Acanthamoeba species are the causative agents of Acanthamoeba keratitis and granulomatous amoebic encephalitis. Members of this amoeba genus are ubiquitous in the environments. In Malaysia, most environmental studies performed to date have targeted the detection and characterisation of Acanthamoeba sp. in different water sources, dust and soil samples collected near human habitats. However, no local study has yet to examine these amoebae in a forest, an isolated terrestrial environment, where human activity is relatively scarce. Further, there are also limited studies to investigate the same globally. The current study reported the isolation, morphological and genotypic characterisations of eleven Acanthamoeba sp. isolated from soils of the Payeh Maga Highland forest, Sarawak, Malaysia. Morphological analysis revealed that nine isolates belonged to Group II, whereas two isolates belonged to Group III as defined by the criteria of Pussard and Pons. The phylogenetic analysis based on complete 18S rRNA gene sequences showed that the isolates belonged to the rare T1 (six isolates), T6 (two isolates) and T13 (three isolates) genotypes. To the best of our knowledge, this is the first report about the detection of T6 Acanthamoeba sp. in this country. Overall, the current findings have enriched the knowledge pertaining to the occurrence, morphological and genotypic characteristics of Acanthamoeba sp. in an isolated terrestrial environment of Malaysia.
  7. Look ML, Tan SB, Hong LL, Ng CG, Yee HA, Lim LY, et al.
    BMJ Support Palliat Care, 2021 Dec;11(4):433-439.
    PMID: 32788274 DOI: 10.1136/bmjspcare-2020-002382
    CONTEXT: There has been increasing evidence of the role of mindfulness-based interventions in improving various health conditions. However, the evidence for the use of mindfulness in the palliative care setting is still lacking.

    OBJECTIVES: The objective of our study was to determine the efficacy of a single session of 20 min mindful breathing in alleviating multiple symptoms in palliative care.

    METHODS: Adult palliative care in patients with at least one symptom scoring ≥5/10 based on the Edmonton Symptom Assessment Scale (ESAS) were recruited from September 2018 to December 2018. Recruited patients were randomly assigned to either 20 min mindful breathing and standard care or standard care alone.

    RESULTS: Forty patients were randomly assigned to standard care plus a 20 min mindful breathing session (n=20) or standard care alone (n=20). There was statistically significant reduction of total ESAS score in the mindful breathing group compared with the control group at minute 20 (U=98, n 1 = n 2 = 20, mean rank 1 = 15.4, mean rank 2 = 25.6, median reduction 1 = 6.5, median reduction 2 = 1.5, z=-2.763, r=0.3, p=0.005).

    CONCLUSION: Our results provided evidence that a single session of 20 min mindful breathing was effective in reducing multiple symptoms rapidly for palliative care patients.

  8. Dong X, Xu S, Liu Y, Wang A, Saripan MI, Li L, et al.
    Cancer Imaging, 2020 Aug 01;20(1):53.
    PMID: 32738913 DOI: 10.1186/s40644-020-00331-0
    BACKGROUND: Convolutional neural networks (CNNs) have been extensively applied to two-dimensional (2D) medical image segmentation, yielding excellent performance. However, their application to three-dimensional (3D) nodule segmentation remains a challenge.

    METHODS: In this study, we propose a multi-view secondary input residual (MV-SIR) convolutional neural network model for 3D lung nodule segmentation using the Lung Image Database Consortium and Image Database Resource Initiative (LIDC-IDRI) dataset of chest computed tomography (CT) images. Lung nodule cubes are prepared from the sample CT images. Further, from the axial, coronal, and sagittal perspectives, multi-view patches are generated with randomly selected voxels in the lung nodule cubes as centers. Our model consists of six submodels, which enable learning of 3D lung nodules sliced into three views of features; each submodel extracts voxel heterogeneity and shape heterogeneity features. We convert the segmentation of 3D lung nodules into voxel classification by inputting the multi-view patches into the model and determine whether the voxel points belong to the nodule. The structure of the secondary input residual submodel comprises a residual block followed by a secondary input module. We integrate the six submodels to classify whether voxel points belong to nodules, and then reconstruct the segmentation image.

    RESULTS: The results of tests conducted using our model and comparison with other existing CNN models indicate that the MV-SIR model achieves excellent results in the 3D segmentation of pulmonary nodules, with a Dice coefficient of 0.926 and an average surface distance of 0.072.

    CONCLUSION: our MV-SIR model can accurately perform 3D segmentation of lung nodules with the same segmentation accuracy as the U-net model.

  9. Fernandez-Orozco R, Li L, Harflett C, Shewry PR, Ward JL
    J Agric Food Chem, 2010 Sep 08;58(17):9341-52.
    PMID: 20707366 DOI: 10.1021/jf102017s
    Phenolic acid content and composition have been determined in 26 wheat genotypes grown in Hungary over three consecutive years and at three additional locations (France, United Kingdom, and Poland) during the third year. Fractions comprising free, soluble conjugated, and bound phenolic acids were analyzed using HPLC with measurements being made for individual phenolic acids in each fraction. Statistically significant differences in phenolic acid content occurred across the different growing locations with the average total phenolic acid content being highest in the genotypes grown in Hungary. The growth year in Hungary also had a large impact, especially on the free and conjugated phenolic acid contents. Certain genotypes were more resistant to environmental impacts than others. Of the genotypes with high levels of total phenolic acids, Lynx, Riband, Tommi, and Cadenza were most stable with respect to their total contents, whereas Valoris, Herzog, and Malacca, also high in phenolic acid content, were least stable. Of the three fractions analyzed, the free and conjugated phenolic acids were most variable and were also susceptible to the effect of environment, whereas bound phenolic acids, which comprised the greatest proportion of the total phenolic acids, were the most stable.
  10. Attah AO, Sanggari A, Li LI, Nik Him NAII, Ismail AH, Meor Termizi FH
    Parasitol Res, 2023 Jan;122(1):1-10.
    PMID: 36434314 DOI: 10.1007/s00436-022-07731-0
    There has been increasing interest in the study of Blastocystis in the last two decades. Many studies have been carried out in human and animal hosts including environmental sources, but there is little or no information on the occurrence of Blastocystis in water sources worldwide. Therefore, this study aimed at assessing the occurrence of Blastocystis in water sources across the world from 2005 to 2022, noting the method of detection and the distribution of the subtypes from various water sources. A literature search was performed on internet-based databases including Google search, PubMed, Scopus, and Web of Science. Upon application of the criteria for inclusion, 25 articles revealing the occurrence of Blastocystis in water sources in 15 countries were included in the review. Blastocystis occurrence varies across water sources ranging from 0% in a drinking water source in Venezuela to 100% in rivers; well water, stored water, and fishpond in Nepal and Malaysia; and fountain water, irrigation water, and rainwater in Italy, Spain, and Thailand. The occurrence of the parasite was significantly associated with the coliform count, temperature, conductivity, dissolved oxygen, turbidity, total dissolved solids, and chemical oxygen demand. A total of 11 Blastocystis subtypes were identified in water sources worldwide, namely, ST1-ST8, ST10, ST23, and ST26 in which ST1 and ST3 were the most prevalent subtypes. Considering the importance of Blastocystis as a waterborne parasite, the subtype distribution and morphological distinction in water sources need to be carried out using molecular and electron microscopic techniques. Existing studies have covered only about 10% of the world's countries.
  11. Bao X, Huo G, Li L, Cao X, Liu Y, Lakshmipriya T, et al.
    J Anal Methods Chem, 2019;2019:5676159.
    PMID: 31827972 DOI: 10.1155/2019/5676159
    Gestational hypertension is one of the complicated disorders during pregnancy; it causes the significant risks, such as placental abruption, neonatal deaths, and maternal deaths. Hypertension is also responsible for the metabolic and cardiovascular issues to the mother after the years of pregnancy. Identifying and treating gestational hypertension during pregnancy by a suitable biomarker is mandatory for the healthy mother and foetus development. Cortisol has been found as a steroid hormone that is secreted by the adrenal gland and plays a pivotal role in gestational hypertension. A normal circulating level of cortisol is involved in the regulation of blood pressure, and it is necessary to monitor the changes in the level of cortisol during pregnancy. In this work, aptamer-based colorimetric assay is demonstrated as a model with gold nanorod to quantify the level of cortisol using the coordinated aggregation (at 500 mM of NaCl) and dispersion (with 10 μM of aptamer), evidenced by the scanning electron microscopy observation and UV-visible spectroscopy analysis. This colorimetric assay is an easier visual detection and reached the limit of detection of cortisol at 0.25 mg/mL. This method is reliable to identify the condition of gestational hypertension during the pregnancy period.
  12. Xu G, You D, Wong L, Duan D, Kong F, Zhang X, et al.
    Eur J Endocrinol, 2019 Apr;180(4):243-255.
    PMID: 30668524 DOI: 10.1530/EJE-18-0792
    Objective: Previous studies have shown sex-specific differences in all-cause and CHD mortality in type 2 diabetes. We performed a systematic review and meta-analysis to provide a global picture of the estimated influence of type 2 diabetes on the risk of all-cause and CHD mortality in women vs men.

    Methods: We systematically searched PubMed, EMBASE and Web of Science for studies published from their starting dates to Aug 7, 2018. The sex-specific hazard ratios (HRs) and their pooled ratio (women vs men) of all-cause and CHD mortality associated with type 2 diabetes were obtained through an inverse variance-weighted random-effects meta-analysis. Subgroup analyses were used to explore the potential sources of heterogeneity.

    Results: The 35 analyzed prospective cohort studies included 2 314 292 individuals, among whom 254 038 all-cause deaths occurred. The pooled women vs men ratio of the HRs for all-cause and CHD mortality were 1.17 (95% CI: 1.12-1.23, I2 = 81.6%) and 1.97 (95% CI: 1.49-2.61, I2 = 86.4%), respectively. The pooled estimate of the HR for all-cause mortality was approximately 1.30 in articles in which the duration of follow-up was longer than 10 years and 1.10 in articles in which the duration of follow-up was less than 10 years. The pooled HRs for all-cause mortality in patients with type 2 diabetes was 2.33 (95% CI: 2.02-2.69) in women and 1.91 (95% CI: 1.72-2.12) in men, compared with their healthy counterparts.

    Conclusions: The effect of diabetes on all-cause and CHD mortality is approximately 17 and 97% greater, respectively, for women than for men.

  13. Huang L, Liu Z, Li H, Wang Y, Li Y, Zhu Y, et al.
    Geohealth, 2020 Jul 07.
    PMID: 32838101 DOI: 10.1029/2020GH000272
    The outbreak of COVID-19 in China has led to massive lockdowns in order to reduce the spread of the epidemic and control human-to-human transmission. Subsequent reductions in various anthropogenic activities have led to improved air quality during the lockdown. In this study, we apply a widely used exposure-response function to estimate the short-term health impacts associated with PM2.5 changes over the Yangtze River Delta (YRD) region due to COVID-19 lockdown. Concentrations of PM2.5 during lockdown period reduced by 22.9% to 54.0% compared to pre-lockdown level. Estimated PM2.5-related daily premature mortality during lockdown period is 895 (95% confidential interval: 637-1081), which is 43.3% lower than pre-lockdown period and 46.5% lower compared with averages of 2017-2019. According to our calculation, total number of avoided premature death associated PM2.5 reduction during the lockdown is estimated to be 42.4 thousand over the YRD region, with Shanghai, Wenzhou, Suzhou (Jiangsu province), Nanjing, and Nantong being the top five cities with largest health benefits. Avoided premature mortality is mostly contributed by reduced death associated with stroke (16.9 thousand, accounting for 40.0%), ischemic heart disease (14.0 thousand, 33.2%) and chronic obstructive pulmonary disease (7.6 thousand, 18.0%). Our calculations do not support or advocate any idea that pandemics produce a positive note to community health. We simply present health benefits from air pollution improvement due to large emission reductions from lowered human and industrial activities. Our results show that continuous efforts to improve air quality are essential to protect public health, especially over city-clusters with dense population.
  14. Huang L, Zhu Y, Liu H, Wang Y, Allen DT, Chel Gee Ooi M, et al.
    Environ Int, 2023 Jan;171:107710.
    PMID: 36566719 DOI: 10.1016/j.envint.2022.107710
    In recent years, ozone pollution in China has been shown to increase in frequency and persistence despite the concentrations of fine particulate matter (PM2.5) decreasing steadily. Open crop straw burning (OCSB) activities are extensive in China and emit large amounts of trace gases during a short period that could lead to elevated ozone concentrations. This study addresses the impacts of OCSB emissions on ground-level ozone concentration and the associated health impact in China. Total VOCs and NOx emissions from OCSB in 2018 were 798.8 Gg and 80.6 Gg, respectively, with high emissions in Northeast China (31.7%) and North China (23.7%). Based on simulations conducted for 2018, OCSB emissions are estimated to contribute up to 0.95 µg/m3 increase in annual averaged maximum daily 8-hour (MDA8) ozone and up to 1.35 µg/m3 for the ozone season average. The significant impact of OCSB emissions on ozone is mainly characterized by localized and episodic (e.g., daily) changes in ozone concentration, up to 20 µg/m3 in North China and Yangtze River Delta region and even more in Northeast China during the burning season. With the implementation of straw burning bans, VOCs and NOx emissions from OCSB dropped substantially by 46.9%, particularly over YRD (76%) and North China (60%). Consequently, reduced OCSB emissions result in an overall decrease in annual averaged MDA8 ozone, and reductions in monthly MDA8 ozone could be over 10 µg/m3 in North China. The number of avoided premature death due to reduced OCSB emissions (considering both PM2.5 and ozone) is estimated to be 6120 (95% Confidence Interval: 5320-6800), with most health benefits gained over east and central China. Our results illustrate the effectiveness of straw burning bans in reducing ozone concentrations at annual and national scales and the substantial ozone impacts from OCSB events at localized and episodic scales.
  15. Liao T, Li XR, Fan L, Zhang B, Zheng WM, Hua JJ, et al.
    Front Microbiol, 2024;15:1433127.
    PMID: 39234548 DOI: 10.3389/fmicb.2024.1433127
    Kombucha, a fermented tea prepared with a symbiotic culture of bacteria and yeast (SCOBY), offers a unique and unpredictable home-brewed fermentation process. Therefore, the need for a controlled kombucha fermentation process has become evident, which requiring a thorough understanding of the microbial composition and its relationship with the metabolites produced. In this study, we investigated the dynamics of microbial communities and metabolites over a 12-day fermentation period of a conventional kombucha-making process. Our findings revealed similarities between the microbial communities in the early (0-2 days) and late (10-12 days) fermentation periods, supporting the principle of back-slopping fermentation. Untargeted metabolite analysis unveiled the presence of harmful biogenic amines in the produced kombucha, with concentrations increasing progressively throughout fermentation, albeit showing relatively lower abundance on days 8 and 12. Additionally, a contrasting trend between ethanol and caffeine content was observed. Canonical correspondence analysis highlighted strong positive correlations between specific bacterial/yeast strains and identified metabolites. In conclusion, our study sheds light on the microbial and metabolite dynamics of kombucha fermentation, emphasizing the importance of microbial control and quality assurance measures in the production process.
  16. Gobe GC, Ng KL, Small DM, Vesey DA, Johnson DW, Samaratunga H, et al.
    Biochem Biophys Res Commun, 2016 Apr 22;473(1):47-53.
    PMID: 26995091 DOI: 10.1016/j.bbrc.2016.03.048
    Apoptosis repressor with caspase recruitment domain (ARC), an endogenous inhibitor of apoptosis, is upregulated in a number of human cancers, thereby conferring drug resistance and giving a rationale for the inhibition of ARC to overcome drug resistance. Our hypothesis was that ARC would be similarly upregulated and targetable for therapy in renal cell carcinoma (RCC). Expression of ARC was assessed in 85 human RCC samples and paired non-neoplastic kidney by qPCR and immunohistochemistry, as well as in four RCC cell lines by qPCR, Western immunoblot and confocal microscopy. Contrary to expectations, ARC was significantly decreased in the majority of clear cell RCC and in three (ACHN, Caki-1 and 786-0) of the four RCC cell lines compared with the HK-2 non-cancerous human proximal tubular epithelial cell line. Inhibition of ARC with shRNA in the RCC cell line (SN12K1) that had shown increased ARC expression conferred resistance to Sunitinib, and upregulated interleukin-6 (IL-6) and vascular endothelial growth factor (VEGF). We therefore propose that decreased ARC, particularly in clear cell RCC, confers resistance to targeted therapy through restoration of tyrosine kinase-independent alternate angiogenesis pathways. Although the results are contrary to expectations from other cancer studies, they were confirmed here with multiple analytical methods. We believe the highly heterogeneous nature of cancers like RCC predicate that expression patterns of molecules must be interpreted in relation to respective matched non-neoplastic regions. In the current study, this procedure indicated that ARC is decreased in RCC.
  17. Yi X, Yin S, Huang L, Li H, Wang Y, Wang Q, et al.
    Sci Total Environ, 2021 Jun 01;771:144644.
    PMID: 33736175 DOI: 10.1016/j.scitotenv.2020.144644
    Chlorine radical plays an important role in the formation of ozone and secondary aerosols in the troposphere. It is hence important to develop comprehensive emissions inventory of chlorine precursors in order to enhance our understanding of the role of chlorine chemistry in ozone and secondary pollution issues. Based on a bottom-up methodology, this study presents a comprehensive emission inventory for major atomic chlorine precursors in the Yangtze River Delta (YRD) region of China for the year 2017. Four primary chlorine precursors are considered in this study: hydrogen chloride (HCl), fine particulate chloride (Cl-) (Cl- in PM2.5), chlorine gas (Cl2), and hypochlorous acid (HClO) with emissions estimated for twelve source categories. The total emissions of these four species in the YRD region are estimated to be 20,424 t, 15,719 t, 1556 and 9331 t, respectively. The emissions of HCl are substantial, with major emissions from biomass burning and coal combustion, together accounting for 68% of the total HCl emissions. Fine particulate Cl- is mainly emitted from industrial processing, biomass burning and waste incineration. The emissions of Cl2 and HClO are mainly associated with usage of chlorine-containing disinfectants, for example, water treatment, wastewater treatment, and swimming pools. Emissions of each chlorine precursor are spatially allocated based on the characteristics of individual source category. This study provides important basic dataset for further studies with respect to the effects of chlorine chemistry on the formation of air pollution complex in the YRD region.
  18. Li L, An J, Zhou M, Qiao L, Zhu S, Yan R, et al.
    Environ Sci Technol, 2018 Dec 18;52(24):14216-14227.
    PMID: 30288976 DOI: 10.1021/acs.est.8b01211
    An integrated source apportionment methodology is developed by amalgamating the receptor-oriented model (ROM) and source-oriented numerical simulations (SOM) together to eliminate the weaknesses of individual SA methods. This approach attempts to apportion and dissect the PM2.5 sources in the Yangtze River Delta region during winter. First, three ROM models (CMB, PMF, ME2) are applied and compared for the preliminary SA results, with information from PM2.5 sampling and lab analysis during the winter seasons. The detailed source category contribution of SOM to PM2.5 is further simulated using the WRF-CAMx model. The two pieces of information from both ROM and SOM are then stitched together to give a comprehensive information on the PM2.5 sources over the region. With the integrated approach, the detailed contributing sources of the ambient PM2.5 at different receptors including rural and urban, coastal and in-land, northern and southern receptors are analyzed. The results are compared with previous data and shows good agreement. This integrative approach is more comprehensive and is able to produce a more profound and detailed understanding between the sources and receptors, compared with single models.
  19. Zheng Y, Ooi MCG, Juneng L, Wee HB, Latif MT, Nadzir MSM, et al.
    Sci Total Environ, 2023 Nov 25;901:166430.
    PMID: 37607626 DOI: 10.1016/j.scitotenv.2023.166430
    Climate change is thought to influence the composition of atmospheric air, but little is known about the direct relationship between these variables, especially in a hot tropical climate like that of Malaysia. This work summarizes and analyzes the climate state and air quality of Peninsular Malaysia based on selected ground-based observations of the temperature, precipitation, relative humidity, wind speed, wind direction and concentrations of PM10, O3, CO, NO2, and SO2 over the last 20 years (2000-2019). The relationship between the climate state and air quality is analyzed using the Pearson correlation and canonical correlation analysis (CCA) methods is employed to predict the degree of change in the future air quality under different warming scenarios. It is found that the Peninsular Malaysia mainly experienced strong precipitation in the central and mountainous regions, while air pollutants are primarily concentrated in densely populated areas. Throughout the period of study (interannual, monthly, and diurnal time series analyses), Peninsular Malaysia became warmer and drier, with a significant increase in temperature (+4.2 %), decrease in the relative humidity (-4.5 %), and greater fluctuation in precipitation amount. The pollution conditions have worsened; there has been an increase in the PM10 (+16.4 %), O3 (+39.5 %), and NO2 (+2.1 %) concentration over the last 20 years. However, the amount of SO2 (-53.6 %) and CO (-20.6 %) decreased significantly. The analysis of the monthly variation shows a strong bimodality of the PM10 and O3 concentrations that corresponds to the monsoon transition. Intensive diurnal fluctuations and correlations are observed for all the variables in this study. According to the CCA, the air quality factors are strongly correlated with meteorological factors; in particular, the CO, O3, and PM10 concentrations interact strongly with the air temperature. These findings show that the future air quality in Peninsular Malaysia has high possibility to deteriorate under warming condition.
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