Displaying publications 21 - 40 of 279 in total

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  1. Al-Qazaz HKh, Hassali MA, Shafie AA, Sulaiman SA, Sundram S, Morisky DE
    Diabetes Res Clin Pract, 2010 Nov;90(2):216-21.
    PMID: 20832888 DOI: 10.1016/j.diabres.2010.08.012
    AIMS:
    To translate and examine the psychometric properties of the Malaysian version of the Morisky Medication Adherence Scale (MMAS) among patients with type 2 diabetes.

    METHODS:
    A standard "forward-backward" procedure was used to translate MMAS into Malay language. It was later validated on a convenience sample of 223 type 2 diabetes outpatients between May and September 2009. Reliability was tested for internal consistency. Validity was confirmed using convergent and known group validity.

    RESULTS:
    Employing the recommended scoring method, the mean±SD of MMAS scores was 6.13±1.72. Moderate internal consistency was found (Cronbach's α=0.675), the test-retest reliability value was 0.816 (p<0.001). A positive correlation between the eight- and four-item MMAS was found (r=0.792; p<0.01). A significant relationship between MMAS categories and HbA1c categories (χ(2)=20.261; p≥0.001) was found. The MMAS sensitivity and specificity, with positive and negative predictive values were 77.61%, 45.37%, 46.84% and 76.56%, respectively.

    CONCLUSIONS:
    The findings of this validation study indicate that the Malaysian version of the MMAS is a reliable and valid measure of medication adherence which can now be used.
  2. Al-Qazaz HKh, Sulaiman SA, Hassali MA, Shafie AA, Sundram S, Al-Nuri R, et al.
    Int J Clin Pharm, 2011 Dec;33(6):1028-35.
    PMID: 22083724 DOI: 10.1007/s11096-011-9582-2
    BACKGROUND: Most of interventions that have attempted to improve medication adherence in type 2 diabetes have been educational; on the assumption that knowledge regarding diabetes might affect patients' adherence to their treatment regimen.
    OBJECTIVES: The purpose of the study was to investigate any association of knowledge and medication adherence with glycemic control in patients with type 2 diabetes mellitus. Setting The study was conducted at the Diabetes Outpatients Clinic, Hospital Pulau Pinang.
    METHODS: A cross-sectional study was conducted with a convenience sample of 540 adult patients with type 2 diabetes attending the clinic. A questionnaire including previously validated Michigan Diabetes Knowledge Test and Morisky Medication Adherence Scale was used and the patients' medical records were reviewed for haemoglobin A1C (HbA1C) levels and other disease-related information. A total of 35 (6.48%) patients were excluded after data collection due to lack of HbA1C results.
    RESULTS: Five hundred and five patients were included in the final analysis, with a mean age of 58.15 years (SD = 9.16), 50.7% males and median HbA1C of 7.6 (IQR was 6.7-8.9). The median total knowledge score was 7.0 (IQR was 5.0-10.0) while the median adherence score was 6.5 (IQR was 4.75-7.75). Significant correlations were found between the three variables (HbA1C, knowledge and adherence). A significantly higher score for knowledge and adherence (P < 0.05) was found in those patients with lower HbA1C. Higher diabetes knowledge, higher medication adherence and using mono-therapy were significant predictors of good glycemic control in the multivariate analysis.
    CONCLUSION: Patients' knowledge about diabetes is associated with better medication adherence and better glycemic control. In addition to other factors affecting medication adherence and glycemic control, healthcare providers should pay attention to knowledge about diabetes that the patients carry towards medication adherence.

    Study site: Diabetes Outpatients Clinic, Hospital Pulau Pinang, Pulau Pinang, Malaysia
  3. AlOtaibi TM, Gheith OA, Abuelmagd MM, Adel M, Alqallaf AK, Elserwy NA, et al.
    Clin Transplant, 2021 Jun;35(6):e14297.
    PMID: 33768630 DOI: 10.1111/ctr.14297
    INTRODUCTION: COVID-19 is an ongoing pandemic with high morbidity and mortality and with a reported high risk of severe disease in kidney transplant recipients (KTR).

    AIM: We aimed to report the largest number of COVID-19-positive cases in KTR in a single center and to discuss their demographics, management, and evolution.

    METHODS: We enrolled all the two thousand KTR followed up in our center in Kuwait and collected the data of all COVID-19-positive KTR (104) from the start of the outbreak till the end of July 2020 and have reported the clinical features, management details, and both patient and graft outcomes.

    RESULTS: Out of the one hundred and four cases reported, most of them were males aged 49.3 ± 14.7 years. Eighty-two of them needed hospitalization, of which thirty-one were managed in the intensive care unit (ICU). Main comorbidities among these patients were hypertension in 64.4%, diabetes in 51%, and ischemic heart disease in 20.2%. Management strategies included anticoagulation in 56.7%, withdrawal of antimetabolites in 54.8%, calcineurin inhibitor (CNI) withdrawal in 33.7%, the addition of antibiotics in 57.7%, Tocilizumab in 8.7%, and antivirals in 16.3%. During a follow-up of 30 days, the reported number of acute kidney injury (AKI) was 28.7%, respiratory failure requiring oxygen therapy 46.2%, and overall mortality rate was 10.6% with hospital mortality of 13.4% including an ICU mortality rate of 35.5%.

    CONCLUSION: Better outcome of COVID-19-positive KTR in our cohort during this unremitting stage could be due to the younger age of patients and early optimized management of anticoagulation, modification of immunosuppression, and prompt treatment of secondary bacterial infections. Mild cases can successfully be managed at home without any change in immunosuppression.

  4. AlThuwaynee OF, Kim SW, Najemaden MA, Aydda A, Balogun AL, Fayyadh MM, et al.
    Environ Sci Pollut Res Int, 2021 Aug;28(32):43544-43566.
    PMID: 33834339 DOI: 10.1007/s11356-021-13255-4
    This study investigates uncertainty in machine learning that can occur when there is significant variance in the prediction importance level of the independent variables, especially when the ROC fails to reflect the unbalanced effect of prediction variables. A variable drop-off loop function, based on the concept of early termination for reduction of model capacity, regularization, and generalization control, was tested. A susceptibility index for airborne particulate matter of less than 10 μm diameter (PM10) was modeled using monthly maximum values and spectral bands and indices from Landsat 8 imagery, and Open Street Maps were used to prepare a range of independent variables. Probability and classification index maps were prepared using extreme-gradient boosting (XGBOOST) and random forest (RF) algorithms. These were assessed against utility criteria such as a confusion matrix of overall accuracy, quantity of variables, processing delay, degree of overfitting, importance distribution, and area under the receiver operating characteristic curve (ROC).
  5. Alfadl AA, Hassali MA, Ibrahim MI
    Res Social Adm Pharm, 2013 May-Jun;9(3):302-10.
    PMID: 22835708 DOI: 10.1016/j.sapharm.2012.05.002
    The counterfeit drug trade has become widespread and has developed into a substantial threat to both the public's health and the pharmaceutical industry.
  6. Alfaleh MA, Fahmy O, Al-Rabia MW, Abourehab MAS, Ahmed OAA, Fahmy UA, et al.
    Sci Rep, 2022 Nov 14;12(1):19446.
    PMID: 36376469 DOI: 10.1038/s41598-022-24151-3
    As a hydroxymethylglutaryl coenzyme A (HMG-CoA) reductase inhibitor, Fluvastatin (FLV) is used for reducing low-density lipoprotein (LDL) cholesterol as well as to prevent cardiovascular problems. FLV showed cell line cytotoxicity and antitumor effect. Melittin (MEL) exhibits antineoplastic activity and is known to be promising as a therapeutic option for cancer patients. The aim of this work was to investigate the combination of FLV with MEL loaded hybrid formula of phospholipid (PL) with alpha lipoic acid (ALA) nanoparticles to maximize anticancer tendencies. This study examines the optimization of the prepared formulation in order to minimize nanoparticles size and maximize zeta potential to potentiate cytotoxic potentialities in colon cancer cells (Caco2), cell viability, cell cycle analysis and annexin V were tested. In addition to biological markers as P53, Bax, bcl2 and Caspase 3 evaluation The combination involving FLV PL ALA MEL showed enhanced cytotoxic potentiality (IC50 = 9.242 ± 0.35 µg/mL), about twofold lower, compared to the raw FLV (IC50 = 21.74 ± 0.82 µg/mL). According to studies analyzing cell cycle, optimized FLV PL ALA MEL was found to inhibit Caco2 colon cancer cells more significantly than other therapeutic treatments, wherein a higher number of cells were found to accumulate over G2/M and pre-G1 phases, whereas G0/G1/S phases witnessed the accumulation of a lower number of cells. The optimized formulation may pave the way for a novel and more efficacious treatment for colon cancer.
  7. Algaifi HA, Mustafa Mohamed A, Alsuhaibani E, Shahidan S, Alrshoudi F, Huseien GF, et al.
    Polymers (Basel), 2021 Aug 16;13(16).
    PMID: 34451289 DOI: 10.3390/polym13162750
    Although free-cement-based alkali-activated paste, mortar, and concrete have been recognised as sustainable and environmental-friendly materials, a considerable amount of effort is still being channeled to ascertain the best binary or ternary binders that would satisfy the requirements of strength and durability as well as environmental aspects. In this study, the mechanical properties of alkali-activated mortar (AAM) made with binary binders, involving fly ash (FA) and granulated blast-furnace slag (GBFS) as well as bottle glass waste nano-silica powder (BGWNP), were opti-mised using both experimentally and optimisation modelling through three scenarios. In the first scenario, the addition of BGWNP varied from 5% to 20%, while FA and GBFS were kept constant (30:70). In the second and third scenarios, BGWNP (5-20%) was added as the partial replacement of FA and GBFS, separately. The results show that the combination of binary binders (FA and GBFS) and BGWNP increased AAM's strength compared to that of the control mixture for all scenarios. In addition, the findings also demonstrated that the replacement of FA by BGWNP was the most significant, while the effect of GBFS replacement by BGWNP was less significant. In particular, the highest improvement in compressive strength was recorded when FA, GBFS, and BGWNP were 61.6%, 30%, and 8.4%, respectively. Furthermore, the results of ANOVA (p values < 0.0001 and high F-values) as well as several statistical validation methods (R > 0.9, RAE < 0.1, RSE < 0.013, and RRSE < 0.116) confirmed that all the models were robust, reliable, and significant. Similarly, the data variation was found to be less than 5%, and the difference between the predicted R2 and adj. R2 was very small (<0.2), thus confirming that the proposed non-linear quadratic equations had the capability to predict for further observation. In conclusion, the use of BGWNP in AAM could act as a beneficial and sustainable strategy, not only to address environmental issues (e.g., landfill) but to also enhance strength properties.
  8. Ali MA, Ismail R, Choon TS, Yoon YK, Wei AC, Pandian S, et al.
    Acta Pol Pharm, 2011 May-Jun;68(3):343-8.
    PMID: 21648188
    A series of novel 3-(substituted phenyl)-6,7-dimethoxy-3a,4-dihydro-3H-indeno[1,2-c]isoxazole analogues were synthesized by the reaction of 5,6-dimethoxy-2-[(E)-1-phenylmethylidene]-1-indanone with hydroxylamine hydrochloride. The title compounds were tested for their in vitro anti-HIV activity. Among the compounds, (4g) showed a promising anti-HIV activity in the in vitro testing against IIIB and ROD strains. The IC50 of both IIIB and ROD were found to be 9.05 microM and > 125 microM, respectively.
  9. Ali MS, Kamarudin SK, Masdar MS, Mohamed A
    ScientificWorldJournal, 2014;2014:103709.
    PMID: 25478581 DOI: 10.1155/2014/103709
    Power electronics and fuel cell technologies play an important role in the field of renewable energy. The demand for fuel cells will increase as fuel cells become the main power source for portable applications. In this application, a high-efficiency converter is an essential requirement and a key parameter of the overall system. This is because the size, cost, efficiency, and reliability of the overall system for portable applications primarily depend on the converter. Therefore, the selection of an appropriate converter topology is an important and fundamental aspect of designing a fuel cell system for portable applications as the converter alone plays a major role in determining the overall performance of the system. This paper presents a review of power electronics applications in fuel cell systems, which include various topology combinations of DC converters and AC inverters and which are primarily used in fuel cell systems for portable or stand-alone applications. This paper also reviews the switching techniques used in power conditioning for fuel cell systems. Finally, this paper addresses the current problem encountered with DC converters and AC inverter.
  10. Alkadhimi A, Dawood OT, Hassali MA
    Pharm Pract (Granada), 2020 12 12;18(4):2095.
    PMID: 33343772 DOI: 10.18549/PharmPract.2020.4.2095
    Objective: This study aimed to understand the dispensing practice of antibiotics in community pharmacy in Iraq, in addition to explore the community pharmacists' perception about dispensing antibiotics without prescription.

    Methods: A qualitative design was conducted on community pharmacists in Baghdad, Iraq. Pharmacists were selected conveniently from different gender, age group, pharmacy type and years of experience. Face-to-face semi-structure interview was used with all the pharmacists to get in-depth understanding about their dispensing practice of antibiotics without prescription in community pharmacy. The data was coded and classified for thematic analysis.

    Results: This study found that dispensing of antibiotics without prescription was a common practice in community pharmacy. Pharmacists' perception towards dispensing antibiotics without prescription was associated with the medical condition, safety and efficacy of antibiotics, patients request antibiotics by name, emergency cases, regular customer, promotions from pharmaceutical companies, saving time and cost, brand medications, and poor healthcare services. In addition, there were inadequate knowledge about antibiotic resistance and lack of awareness about antibiotic stewardship leading to inappropriate dispensing practice.

    Conclusions: Community pharmacists have poor perception towards dispensing antibiotics without prescription. Educational interventions about antibiotics use focusing on community pharmacists are needed. This will help to optimize the practice of dispensing of antibiotics in the community. In addition, training programs about antibiotic resistance are important to enhance pharmacists' understanding about antibiotic stewardship.

  11. Alkubati SA, Al-Sayaghi KM, Salameh B, Halboup AM, Ahmed WAM, J Alkuwaisi M, et al.
    J Multidiscip Healthc, 2024;17:689-699.
    PMID: 38370607 DOI: 10.2147/JMDH.S452935
    BACKGROUND: Depression has a negative impact on the health outcomes of hemodialysis (HD) patients, including decreased quality of life and increased morbidity and mortality rates. Therefore, this study aimed to determine the prevalence of depression and its associated factors among HD patients in Hodeida city, Yemen.

    METHODS: A cross-sectional study involving 200 HD patients at the Dialysis Center in Hodeida was conducted from February to May 2022. Data on depression were collected using the 9-item Patient Health Questionnaire (PHQ-9). Association of sociodemographic characteristics of patients with depression were assessed using chi-square, subsequently by multivariable logistic regression. Statistical significance was set at P-values <0.05.

    RESULTS: The response rate was 98% (200/204). Depression was prevalent among 63% of HD patients at the Dialysis Center in Hodeida city. Sex was significantly associated with depression, where female patients were more frequently depressed than males (82.4% vs 56.4%, P < 0.001). In addition, employment status and medical insurance were significantly associated with depression, where unemployed patients were more frequently depressed than employed patients (67.6% vs 52.5%, P = 0.041) and patients with medical insurance were less frequently depressed than their counterparts (47.1% vs 66.3%, P = 0.035).

    CONCLUSION: Depression is highly prevalent among HD patients in Hodeida city. Female sex, unemployment and lack of medical insurance are predictors of depression among HD patients. These findings emphasize the urgent need for targeted interventions.

    IMPLICATIONS FOR PRACTICE: Depression is common among HD patients, so that, psychiatric physicians and nurses are increasingly needed in HD centers to implement mental health assessment of patients for depression signs and symptoms to help in early diagnosis and management of depression in order to improve patients' quality of life and preventing negative outcomes.

  12. Alsharqi M, Huckstep OJ, Lapidaire W, Williamson W, Mohamed A, Tan CMJ, et al.
    Echocardiography, 2021 Aug;38(8):1319-1326.
    PMID: 34185918 DOI: 10.1111/echo.15149
    AIMS: To investigate the left ventricular response to exercise in young adults with hypertension, and identify whether this response can be predicted from changes in left atrial function at rest.

    METHODS: A total of 127 adults aged 18-40 years who completed clinical blood pressure assessment and echocardiography phenotyping at rest and during cardiopulmonary exercise testing, were included. Measurements were compared between participants with suboptimal blood pressure ≥120/80mm Hg (n = 68) and optimal blood pressure <120/80mm Hg (n = 59). Left ventricular systolic function during exercise was obtained from an apical four chamber view, while resting left atrial function was assessed from apical four and two chamber views.

    RESULTS: Participants with suboptimal blood pressure had higher left ventricular mass (p = 0.031) and reduced mitral E velocity (p = 0.02) at rest but no other cardiac differences. During exercise, their rise in left ventricular ejection fraction was reduced (p = 0.001) and they had higher left ventricular end diastolic and systolic volumes (p = 0.001 and p = 0.001, respectively). Resting cardiac size predicted left ventricular volumes during exercise but only left atrial booster pump function predicted the left ventricular ejection fraction response ( β = .29, p = 0.011). This association persisted after adjustment for age, sex, body mass index, and mean arterial pressure.

    CONCLUSION: Young adults with suboptimal blood pressure have a reduced left ventricular systolic response to exercise, which can be predicted by their left atrial booster pump function at rest. Echocardiographic measures of left atrial function may provide an early marker of functionally relevant, subclinical, cardiac remodelling in young adults with hypertension.

  13. Alsharqi M, Lapidaire W, Iturria-Medina Y, Xiong Z, Williamson W, Mohamed A, et al.
    Eur Heart J Imaging Methods Pract, 2023 Sep;1(2):qyad029.
    PMID: 37818310 DOI: 10.1093/ehjimp/qyad029
    AIMS: Accurate staging of hypertension-related cardiac changes, before the development of significant left ventricular hypertrophy, could help guide early prevention advice. We evaluated whether a novel semi-supervised machine learning approach could generate a clinically meaningful summary score of cardiac remodelling in hypertension.

    METHODS AND RESULTS: A contrastive trajectories inference approach was applied to data collected from three UK studies of young adults. Low-dimensional variance was identified in 66 echocardiography variables from participants with hypertension (systolic ≥160 mmHg) relative to a normotensive group (systolic < 120 mmHg) using a contrasted principal component analysis. A minimum spanning tree was constructed to derive a normalized score for each individual reflecting extent of cardiac remodelling between zero (health) and one (disease). Model stability and clinical interpretability were evaluated as well as modifiability in response to a 16-week exercise intervention. A total of 411 young adults (29 ± 6 years) were included in the analysis, and, after contrastive dimensionality reduction, 21 variables characterized >80% of data variance. Repeated scores for an individual in cross-validation were stable (root mean squared deviation = 0.1 ± 0.002) with good differentiation of normotensive and hypertensive individuals (area under the receiver operating characteristics 0.98). The derived score followed expected hypertension-related patterns in individual cardiac parameters at baseline and reduced after exercise, proportional to intervention compliance (P = 0.04) and improvement in ventilatory threshold (P = 0.01).

    CONCLUSION: A quantitative score that summarizes hypertension-related cardiac remodelling in young adults can be generated from a computational model. This score might allow more personalized early prevention advice, but further evaluation of clinical applicability is required.

  14. Alwany AB, Youssef GM, Samir OM, Algradee MA, A Yahya NA, Swillam MA, et al.
    Sci Rep, 2023 Jun 26;13(1):10314.
    PMID: 37365289 DOI: 10.1038/s41598-023-37563-6
    ZnS quantum dots (QDs) were fabricated using the co-precipitation technique with no capping agent. The effects of different annealing temperatures (non-annealed, 240 °C and 340 °C for 2 h) on the structural and optical characteristics of ZnS QDs are reported. The samples were examined by XRD, TEM, PL, FTIR, and UV-Vis. An increase in annealing temperature led to an increase in the dot size and a lowering of the energy band gap (EG). The average crystallite size, D of ZnS was between 4.4 and 5.6 nm. The ZnS QDs showed a band gap of 3.75, 3.74 and 3.72 eV for non-annealed, 240 °C, and 340 °C annealed samples. The reflection spectra increased in the visible light and decreased in UV region with an increase in annealing temperature. This work showed that the band gap and size of ZnS QDs could be tuned by varying the annealing temperature.
  15. Amjad Z, Maryam I, Munir M, Salman M, Baraka MA, Mustafa ZU, et al.
    Vaccines (Basel), 2023 Apr 27;11(5).
    PMID: 37243008 DOI: 10.3390/vaccines11050904
    COVID-19 vaccine hesitancy continues to be a widespread problem in Pakistan due to various conspiracy beliefs, myths and misconceptions. Since the hemodialysis population is at a higher risk of contracting infections, we sought to investigate the current COVID-19 immunization status and reasons for any vaccine hesitancy among these patients in Pakistan. This cross-sectional study was conducted among maintenance hemodialysis patients at six hospitals in the Punjab Province of Pakistan. Data were collected anonymously using a questionnaire. A total of 399 hemodialysis patients took part in the survey, the majority of them were male (56%) and aged 45-64 years. A calculated 62.4% of the patients reported receiving at least one dose of the COVID-19 vaccine. Of those vaccinated (249), 73.5% had received two doses and 16.9% had received a booster dose. The most common reasons for vaccination were "being aware they were at high risk" (89.6%), "fear of getting infected" (89.2%) and "willingness to fight against COVID-19-pandemic" (83.9%). Of the 150 patients who had not yet been vaccinated, only 10 showed a willingness to take the COVID-19 vaccine. The major reasons for refusal included "COVID-19 is not a real problem" (75%), the "corona vaccine is a conspiracy (72.1%)" and "I don't need the vaccine" (60.7%). Our study revealed that only 62% patients receiving hemodialysis were partially or completely vaccinated against COVID-19. Consequently, there is a need to initiate aggressive approaches to educate this high-risk population in order to address their concerns with vaccine safety and efficacy as well as correct current myths and misconceptions to improve the COVID-19 immunization status in this population.
  16. Ancrenaz M, Sollmann R, Meijaard E, Hearn AJ, Ross J, Samejima H, et al.
    Sci Rep, 2014;4:4024.
    PMID: 24526001 DOI: 10.1038/srep04024
    The orangutan is the world's largest arboreal mammal, and images of the red ape moving through the tropical forest canopy symbolise its typical arboreal behaviour. Records of terrestrial behaviour are scarce and often associated with habitat disturbance. We conducted a large-scale species-level analysis of ground-based camera-trapping data to evaluate the extent to which Bornean orangutans Pongo pygmaeus come down from the trees to travel terrestrially, and whether they are indeed forced to the ground primarily by anthropogenic forest disturbances. Although the degree of forest disturbance and canopy gap size influenced terrestriality, orangutans were recorded on the ground as frequently in heavily degraded habitats as in primary forests. Furthermore, all age-sex classes were recorded on the ground (flanged males more often). This suggests that terrestrial locomotion is part of the Bornean orangutan's natural behavioural repertoire to a much greater extent than previously thought, and is only modified by habitat disturbance. The capacity of orangutans to come down from the trees may increase their ability to cope with at least smaller-scale forest fragmentation, and to cross moderately open spaces in mosaic landscapes, although the extent of this versatility remains to be investigated.
  17. Anka MS, Hassan L, Adzhar A, Khairani-Bejo S, Mohamad RB, Zainal MA
    BMC Vet Res, 2013;9:230.
    PMID: 24246015 DOI: 10.1186/1746-6148-9-230
    Bovine brucellosis is an important disease affecting cattle characterised by abortion, still birth, reduced milk production, weak foetus and infertility in both males and females. There is wide distribution of the disease among cattle and several wildlife species. Bovine brucellosis is commonly caused by B. abortus and very occasionally B. melitensis and B. suis. The distribution of bovine brucellosis in cattle has not been described in Malaysia. In this paper we describe the distribution, pattern and trend of bovine brucellosis in Peninsular Malaysia between 2000 and 2008 based on serological data obtained from nationwide B. abortus serosurveillance activities in cattle populations.
  18. Ardyani T, Mohamed A, Abu Bakar S, Sagisaka M, Umetsu Y, Hafiz Mamat M, et al.
    Carbohydr Polym, 2020 Jan 15;228:115376.
    PMID: 31635739 DOI: 10.1016/j.carbpol.2019.115376
    The effect of incorporating common dodecyl anionic and cationic surfactants such as dodecyltrimethylammonium bromide (DTAB), dodecylethyldimethylammonium bromide (DDAB), and sodium dodecylsulfate (SDS) in nanocomposites of reduced graphene oxide and nanocellulose are described. The stabilization and electrical properties of the nanocomoposites of reduced graphene oxide (RGO) and nanofibrillated kenaf cellulose (NFC) were characterized using four-point probe electrical conductivity measurements. Raman spectroscopy, field emission scanning electron microscopy, and high-resolution transmission electron microscopy were used to investigate dispersion morphology and the quality of RGO inside the NFC matrices. Small-angle neutron scattering (SANS) was used to study the aggregation behavior of the aqueous surfactant systems and RGO dispersions. The cationic surfactant DTAB proved to be the best choice for stabilization of RGO in NFC, giving enhanced electrical conductivity five orders of magnitude higher than the neat NFC. The results highlight the effects of hydrophilic surfactant moieties on the structure, stability and properties of RGO/NFC composites.
  19. Ardyani T, Mohamed A, Bakar SA, Sagisaka M, Umetsu Y, Mamat MH, et al.
    J Colloid Interface Sci, 2019 Jun 01;545:184-194.
    PMID: 30878784 DOI: 10.1016/j.jcis.2019.03.012
    HYPOTHESIS: The compatibility of surfactants and graphene surfaces can be improved by increasing the number of aromatic groups in the surfactants. Including aniline in the structure may improve the compatibility between surfactant and graphene further still. Surfactants can be modified by incorporating aromatic groups in the hydrophobic chains or hydrophilic headgroups. Therefore, it is of interest to investigate the effects of employing anilinium based surfactants to disperse graphene nanoplatelets (GNPs) in natural rubber latex (NRL) for the fabrication of electrically conductive nanocomposites.

    EXPERIMENTS: New graphene-philic surfactants carrying aromatic moieties in the hydrophilic headgroups and hydrophobic tails were synthesized by swapping the traditional sodium counterion with anilinium. 1H NMR spectroscopy was used to characterize the surfactants. These custom-made surfactants were used to assist the dispersion of GNPs in natural rubber latex matrices for the preparation of conductive nanocomposites. The properties of nanocomposites with the new anilinium surfactants were compared with commercial sodium surfactant sodium dodecylsulfate (SDS), sodium dodecylbenzenesulfonate (SDBS), and the previously synthesized aromatic tri-chain sodium surfactant TC3Ph3 (sodium 1,5-dioxo-1,5-bis(3-phenylpropoxy)-3-((3phenylpropoxy)carbonyl) pentane-2-sulfonate). Structural properties of the nanocomposites were studied using Raman spectroscopy, field emission scanning electron microscopy (FESEM), and high-resolution transmission electron microscopy (HRTEM). Electrical conductivity measurements and Zeta potential measurements were used to assess the relationships between total number of aromatic groups in the surfactant molecular structure and nanocomposite properties. The self-assembly structure of surfactants in aqueous systems and GNP dispersions was assessed using small-angle neutron scattering (SANS).

    FINDINGS: Among these different surfactants, the anilinium version of TC3Ph3 namely TC3Ph3-AN (anilinium 1,5-dioxo-1,5-bis(3-phenylpropoxy)-3-((3phenylpropoxy)carbonyl) pentane-2-sulfonate) was shown to be highly efficient for dispersing GNPs in the NRL matrices, increasing electrical conductivity eleven orders of magnitude higher than the neat rubber latex. Comparisons between the sodium and anilinium surfactants show significant differences in the final properties of the nanocomposites. In general, the strategy of increasing the number of surfactant-borne aromatic groups by incorporating anilinium ions in surfactant headgroups appears to be effective.

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