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Fulltext Pseudomonas Aeruginosa and Streptococcus Pyogenes Exposed to Malaysian Trigona Honey In Vitro Demonstrated Downregulation of Virulence Factor

A Al-Kafaween M, Mohd Hilmi AB, A Nagi Al-Jamal H, A Elsahoryi N, Jaffar N, Khairi Zahri M

Iran J Biotechnol, 2020 Oct;18(4):e2542.
PMID: 34056021 DOI: 10.30498/IJB.2020.2542

Background: Honey has been known as a traditional medicine for centuries with its antibacterial properties. It is considered one of the most enduring substances used in wound management.
Objectives: This study aimed to: (i) evaluate the effects of Malaysian Trigona honey on bacterial structure and (ii) assess the anti-virulence potential of this honey by examining their impacts on the expression of selected genes (involved in stress survival and biofilm formation) in a test organism.
Materials and Methods: Trigona honey's impacts on the bacterial structure (cell morphology) and the expression profiles of select Pseudomonas Aeruginosa and Streptococcus Pyogenes genes were examined using scanning electron microscopy (SEM) and real-time PCR (RT-qPCR) analysis, respectively.
Results: SEM showed that the decreased cell density deformed, disrupted, and damaged cells for both bacteria. RT-qPCR showed that the expression of fleN, fleQ, and fleR genes of P.aeruginosa were decreased, 4.26-fold, 3.80-fold and 2.66- fold respectively. In addition, scpA, ftsY, and emm13 of S.pyogenes were decreased, 2.87-fold, 3.24-fold, and 4.65-fold respectively.
Conclusion: Our results indicate that Trigona honey may be an effective inhibitor and virulence modulator of P. aeruginosa and S. pyogenes via multiple molecular targets. This deduction needs to be investigated in vivo.

Matched MeSH terms: Microscopy, Electron, Scanning
Fulltext Developing Conductive Highly Ordered Zinc Oxide Nanorods by Acetylacetonate-Assisted Growth

A Karim SS, Takamura Y, Tue PT, Tung NT, Kazmi J, Dee CF, et al.

Materials (Basel), 2020 Mar 04;13(5).
PMID: 32143385 DOI: 10.3390/ma13051136

Highly ordered vertically grown zinc oxide nanorods (ZnO NRs) were synthesized on ZnO-coated SiO2/Si substrate using zinc acetylacetonate hydrate as a precursor via a simple hydrothermal method at 85 °C. We used 0.05 M of ZnO solution to facilitate the growth of ZnO NRs and the immersion time was varied from 0.5 to 4 h. The atomic force microscopy revealed the surface roughness of ZnO seed layer used to grow the ZnO NRs. The morphology of vertically grown ZnO NRs was observed by field emission scanning electron microscopy. X-ray diffraction examination and transmission electron microscopy confirmed that the structure of highly ordered ZnO NRs was crystalline with a strong (002) peak corresponded to ZnO hexagonal wurtzite structure. The growth of highly ordered ZnO NRs was favorable due to the continuous supply of Zn2+ ions and chelating agents properties obtained from the acetylacetonate-derived precursor during the synthesis. Two-point probe current-voltage measurement and UV-vis spectroscopy of the ZnO NRs indicated a resistivity and optical bandgap value of 0.44 Ω.cm and 3.35 eV, respectively. The photoluminescence spectrum showed a broad peak centered at 623 nm in the visible region corresponded to the oxygen vacancies from the ZnO NRs. This study demonstrates that acetylacetonate-derived precursors can be used for the production of ZnO NRs-based devices with a potential application in biosensors.

Matched MeSH terms: Microscopy, Electron, Scanning
Fulltext MODIFIED SCREEN-PRINTED ELECTRODE FOR DETERMINATION OF IMIDACLOPRID IN WATER SAMPLES: A PRELIMINARY STUDY

AZRILAWANI AHMAD, NUR ANIS ZAFIRAH ZAINORDIN, NUR AMIRA JAAFAR

UMT Journal of Undergraduate Research, 2019;1(2):41-50.
MyJurnal

A preliminary assessment of a simple and rapid electrochemical method was carried out to analyse imidacloprid (IMI) in water samples using cyclic voltammetry (CV) based on modified screen-printed gold electrode (SPGE). Self-assembled monolayer (SAM) was optimized using 11-mercaptoundecanoic acid (11-MUA) with several parameters such as scan rates, type of supporting electrolyte, and pH of the supporting electrolyte. The modified SPGE showed high suppressed current against the potential due to the formation of a monolayer on the electrode surface. Surface morphology of the electrode was analysed using Scanning Electron Microscopy (SEM) confirming that 11-MUA was present on the modified SPGE. The water samples were collected from GM Peladang, Kuala Terengganu and two locations at Universiti Malaysia Terengganu. Method detection limit was expressed as limit of detection (LOD) and limit of quantification (LOQ) for modified SPGE which were calculated at 3.784 and 12.613 mg/L in water samples, respectively. This study showed that the reduction peak current observed on the modified electrode was lower compared with oxidation peak current. Hence, gold is unsuitable for IMI detection.

Matched MeSH terms: Microscopy, Electron, Scanning
Scanning electron microscopic assessment on surface morphology of preserved human amniotic membrane after gamma sterilisation

Ab Hamid SS, Zahari NK, Yusof N, Hassan A

Cell Tissue Bank, 2014 Mar;15(1):15-24.
PMID: 23187886 DOI: 10.1007/s10561-012-9353-x

Human amniotic membrane that has been processed and sterilised by gamma irradiation is widely used as a biological dressing in surgical applications. The morphological structure of human amniotic membrane was studied under scanning electron microscopy (SEM) to assess effects of gamma radiation on human amniotic membrane following different preservation methods. The amniotic membrane was preserved by either air drying or submerged in glycerol before gamma irradiated at 15, 25 and 35 kGy. Fresh human amniotic membrane, neither preserved nor irradiated was used as the control. The surface morphology of glycerol preserved amnion was found comparable to the fresh amniotic membrane. The cells of the glycerol preserved was beautifully arranged, homogonous in size and tended to round up. The cell structure in the air dried preserved amnion seemed to be flattened and dehydrated. The effects of dehydration on intercellular channels and the microvilli on the cell surface were clearly seen at higher magnifications (10,000×). SEM revealed that the changes of the cell morphology of the glycerol preserved amnion were visible at 35 kGy while the air dried already changed at 25 kGy. Glycerol preservation method is recommended for human amniotic membrane as the cell morphological structure is maintained and radiation doses lower than 25 kGy for sterilization did not affect the appearance of the preserved amnion.

Matched MeSH terms: Microscopy, Electron, Scanning
Chondrocyte-alginate constructs with or without TGF-β1 produces superior extracellular matrix expression than monolayer cultures

Ab-Rahim S, Selvaratnam L, Raghavendran HR, Kamarul T

Mol Cell Biochem, 2013 Apr;376(1-2):11-20.
PMID: 23238871 DOI: 10.1007/s11010-012-1543-0

Tissue engineering approaches often require expansion of cell numbers in vitro to accelerate tissue regenerative processes. Although several studies have used this technique for therapeutic purposes, a major concern involving the use of isolated chondrocyte culture is the reduction of extracellular matrix (ECM) protein expressed due to the transfer of cells from the normal physiological milieu to the artificial 2D environment provided by the cell culture flasks. To overcome this issue, the use of alginate hydrogel beads as a substrate in chondrocyte cultures has been suggested. However, the resultant characteristics of cells embedded in this bead is elusive. To elucidate this, a study using chondrocytes isolated from rabbit knee articular cartilage expanded in vitro as monolayer and chondrocyte-alginate constructs was conducted. Immunohistochemical evaluation and ECM distribution was examined with or without transforming growth factor (TGF-β1) supplement to determine the ability of cells to express major chondrogenic proteins in these environments. Histological examination followed by transmission electron microscopy and scanning electron microscopy was performed to determine the morphology and the ultrastructural characteristics of these cells. Results demonstrated a significant increase in glycosaminoglycan/mg protein levels in chondrocyte cultures grown in alginate construct than in monolayer cultures. In addition, an abundance of ECM protein distribution surrounding chondrocytes cultured in alginate hydrogel was observed. In conclusion, the current study demonstrates that the use of alginate hydrogel beads in chondrocyte cultures with or without TGF-β1 supplement provided superior ECM expression than monolayer cultures.

Matched MeSH terms: Microscopy, Electron, Scanning
Fulltext Characterization of mixed xWO3(1-x)Y2O3 nanoparticle thick film for gas sensing application

Abadi MH, Hamidon MN, Shaari AH, Abdullah N, Misron N, Wagiran R

Sensors (Basel), 2010;10(5):5074-89.
PMID: 22399925 DOI: 10.3390/s100505074

Microstructural, topology, inner morphology, and gas-sensitivity of mixed xWO(3)(1-x)Y(2)O(3) nanoparticles (x = 1, 0.95, 0.9, 0.85, 0.8) thick-film semiconductor gas sensors were studied. The surface topography and inner morphological properties of the mixed powder and sensing film were characterized with X-ray diffraction (XRD), atomic force microscopy (AFM), transmission electron microscopy (TEM), and scanning electron microscopy (SEM). Also, gas sensitivity properties of the printed films were evaluated in the presence of methane (CH(4)) and butane (C(4)H(10)) at up to 500 °C operating temperature of the sensor. The results show that the doping agent can modify some structural properties and gas sensitivity of the mixed powder.

Matched MeSH terms: Microscopy, Electron, Scanning
Fulltext Novel PVDF-PVP Hollow Fiber Membrane Augmented with TiO2 Nanoparticles: Preparation, Characterization and Application for Copper Removal from Leachate

Abba MU, Man HC, Azis RS, Isma Idris A, Hazwan Hamzah M, Yunos KF, et al.

Nanomaterials (Basel), 2021 Feb 04;11(2).
PMID: 33557323 DOI: 10.3390/nano11020399

High proportion of copper has become a global challenge owing to its negative impact on the environment and public health complications. The present study focuses on the fabrication of a polyvinylidene fluoride (PVDF)-polyvinyl pyrrolidone (PVP) fiber membrane incorporated with varying loading (0, 0.5, 1.0, 1.5, and 2.0 wt%) of titanium dioxide (TiO2) nanoparticles via phase inversion technique to achieve hydrophilicity along with high selectivity for copper removal. The developed fibers were characterized based on scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX), permeability, porosity, zeta potential, and contact angle. The improved membrane (with 1.0 wt% TiO2) concentration recorded the maximum flux (223 L/m2·h) and copper rejection (98.18%). Similarly, 1.0 wt% concentration of TiO2 nanoparticles made the membrane matrix more hydrophilic with the least contact angle of 50.01°. The maximum copper adsorption capacity of 69.68 mg/g was attained at 1.0 wt% TiO2 concentration. The experimental data of adsorption capacity were best fitted to the Freundlich isotherm model with R2 value of 0.99573. The hybrid membrane developed in this study has considerably eliminated copper from leachate and the concentration of copper in the permeate was substantially reduced to 0.044 mg/L, which is below standard discharge threshold.

Matched MeSH terms: Microscopy, Electron, Scanning
Fulltext Bioremediation and Electricity Generation by Using Open and Closed Sediment Microbial Fuel Cells

Abbas SZ, Rafatullah M, Khan MA, Siddiqui MR

Front Microbiol, 2018;9:3348.
PMID: 30692985 DOI: 10.3389/fmicb.2018.03348

The industrial contamination of marine sediments with mercury, silver, and zinc in Penang, Malaysia was studied with bio-remediation coupled with power generation using membrane less open (aerated) and closed (non-aerated) sediment microbial fuel cells (SMFCs). The prototype for this SMFC is very similar to a natural aquatic environment because it is not stimulated externally and an oxygen sparger is inserted in the cathode chamber to create the aerobic environment in the open SMFC and no oxygen supplied in the closed SMFC. The open and closed SMFCs were showed the maximum voltage generation 300.5 mV (77.75 mW/m2) and 202.7 mV (45.04 (mW/m2), respectively. The cyclic voltammetry showed the oxidation peak in open SMFCs at +1.9 μA and reduction peak at -0.3 μA but in closed SMFCs oxidation and reduction peaks were noted at +1.5 μA and -1.0 μA, respectively. The overall impedance (anode, cathode and solution) of closed SMFCs was higher than open SMFCs. The charge transfer impedance showed that the rates of substrate oxidation and reduction were very low in the closed SMFCs than open SMFCs. The Nyquist arc indicated that O2 act as electron acceptor in the open SMFCs and CO2 in the closed SMFCs. The highest remediation efficiency of toxic metals [Hg (II) ions, Zn (II) ions, and Ag (I) ions] in the open SMFCs were 95.03%, 86.69%, and 83.65% in closed SMFCs were 69.53%, 66.57%, and 65.33%, respectively, observed during 60-80 days. The scanning electron microscope and 16S rRNA analysis showed diverse exoelectrogenic community in the open SMFCs and closed SMFCs. The results demonstrated that open SMFCs could be employed for the power generation and bioremediation of pollutants.

Matched MeSH terms: Microscopy, Electron, Scanning
Fulltext Effect of surface roughness on accumulation of Streptococcus mutans in nanofilled tooth coloured restorative materials

Abd Rahman, R., Mohamad, D., Ab Ghani, Z., Hasan, H., Abdullah, N.A.

Malaysian Journal of Microscopy, 2015;11(1):16-21.
MyJurnal

The objective of the study was to asses the adhesion of Streptococcus mutans on nanofilled and microfilled composite resin and glass ionomer cement restorative materials. Glass ionomer cements; KetacTM N100 (nanofilled) and Fuji IITM LC (microfilled) and composite resins; FiltekTM Z350 (nanofilled) and FiltekTM Z250 (microhybrid) were packed in acrylic mould of 2 mm thickness and 5 mm diameter. All samples were light-cured and polished with Sof-Lex discs. All materials were cultured with the exponential phase of S. mutans cultivation. Surface roughness values were assessed using Atomic Force Microscope (AFM, Ambios, USA) at time intervals (7hrs, 24 hrs, 7 days, 14 days and 21 days). The morphology of S. mutans on materials was observed after 24 hour incubation of S. mutan on materials under Scanning Electron Microscope (SEM, Quanta FEG 450). Within groups, results showed that both nanofilled materials had lower surface roughness and less adhesion of S. mutans compared to microfilled materials. This study would enhance the clinical knowledge especially in aesthetic area and improve the longevity of the dental restoration.

Matched MeSH terms: Microscopy, Electron, Scanning
Fulltext In vitro ultramorphological assessment of apoptosis induced by zerumbone on (HeLa)

Abdel Wahab SI, Abdul AB, Alzubairi AS, Mohamed Elhassan M, Mohan S

J Biomed Biotechnol, 2009;2009:769568.
PMID: 19343171 DOI: 10.1155/2009/769568

Zerumbone (ZER), a potential anticancer compound, isolated from the fresh rhizomes of Zingiber zerumbet. In this investigation, the cytotoxic properties of ZER were evaluated, on cancer cells of human cervix (HeLa), breast and ovary, and normal cells of Chinese Hamster ovary, using MTT assay. Apoptogenic effects of ZER on HeLa were studied using fluorescence microscopy (AO/PI double staining), scanning and transmission electron microscopy (SEM and TEM), and colorimetric assay of the apoptosis promoter enzyme, caspase-3. The results of MTT assay showed that ZER has less effect on normal cells compared to cancer cells. The lowest IC(50) of ZER was observed on HeLa cells. Cytological observations showed nuclear and chromatin condensation, cell shrinkage, multinucleation, abnormalities of mitochondrial cristae, membrane blebbing, holes, cytoplasmic extrusions and formation of apoptotic bodies as confirmed collectively by double staining of AO/PI, SEM and TEM. Statistical analysis (two-tailed t-test) of differential counting of 200 cells under fluorescence microscope revealed significant difference in apoptotic cells populations between treated and untreated HeLa cells. In addition, ZER has increased the cellular level of caspase-3 on the treated HeLa cells. It could be concluded that ZER was able to produce distinctive morphological features of cell death that corresponds to apoptosis.

Matched MeSH terms: Microscopy, Electron, Scanning
Zerumbone induces apoptosis in T-acute lymphoblastic leukemia cells

Abdelwahab SI, Abdul AB, Mohan S, Taha MM, Syam S, Ibrahim MY, et al.

Leuk. Res., 2011 Feb;35(2):268-71.
PMID: 20708800 DOI: 10.1016/j.leukres.2010.07.025

Zerumbone (ZER) is a potential anticancer natural compound, isolated from Zingiber zerumbet Smith. In this investigation, the anticancer properties of ZER were evaluated on cancer cells of T-acute lymphoblastic leukemia, CEM-ss. The results showed that ZER has cytotoxic effect against CEM-ss cells with an IC(50) of 8.4 ± 1.9 μg/ml (coefficient of variation < 30%). Comparatively, 5-fluorouracil (positive control), imposed an inhibitory effect on CEM-ss cells with an IC(50) of 1.94 ± 0.06 μg/ml. Scanning electron microscopy (SEM) results revealed abnormalities such as membrane blebbing, holes and cytoplasmic extrusions, all of which are characteristics of apoptosis. In addition, ZER has increased the number of TUNEL-positive stain and the cellular level of caspase-3, the hallmarks of apoptosis, on treated CEM-ss cells. It could be concluded that, ZER was able to produce apoptosis on T-acute lymphoblastic leukemia, CEM-ss. The current findings suggest that ZER might be helpful for improving the usefulness of anticancer agents in the therapy of leukemia.

Matched MeSH terms: Microscopy, Electron, Scanning
Fulltext Enhancement of Viscoelastic and Electrical Properties of Magnetorheological Elastomers with Nanosized Ni-Mg Cobalt-Ferrites as Fillers

Abdul Aziz SA, Mazlan SA, Ubaidillah U, Shabdin MK, Yunus NA, Nordin NA, et al.

Materials (Basel), 2019 Oct 28;12(21).
PMID: 31661837 DOI: 10.3390/ma12213531

Carbon-based particles, such as graphite and graphene, have been widely used as a filler in magnetorheological elastomer (MRE) fabrication in order to obtain electrical properties of the material. However, these kinds of fillers normally require a very high concentration of particles to enhance the conductivity property. Therefore, in this study, the nanosized Ni-Mg cobalt ferrite is introduced as a filler to soften MRE and, at the same time, improve magnetic, rheological, and conductivity properties. Three types of MRE samples without and with different compositions of Mg, namely Co0.5Ni0.2Mg0.3Fe2O4 (A1) and Co0.5Ni0.1Mg0.4Fe2O4 (A2), are fabricated. The characterization related to the micrograph, magnetic, and rheological properties of the MRE samples are analyzed using scanning electron microscopy (SEM), vibrating sample magnetometer (VSM), and the rheometer. Meanwhile, the effect of the nanosized Ni-Mg cobalt ferrites on the electrical resistance property is investigated and compared with the different Mg compositions. It is shown that the storage modulus of the MRE sample with the nanosized Ni-Mg cobalt ferrites is 43% higher than that of the MRE sample without the nanomaterials. In addition, it is demonstrated that MREs with the nanosized Ni-Mg cobalt ferrites exhibit relatively low electrical resistance at the on-state as compared to the off-state condition, because MRE with a higher Mg composition shows lower electrical resistance when higher current flow occurs through the materials. This salient property of the proposed MRE can be effectively and potentially used as an actuator to control the viscoelastic property of the magnetic field or sensors to measure the strain of the flexible structures by the electrical resistance signal.

Matched MeSH terms: Microscopy, Electron, Scanning
Fulltext Wear of rotary instruments: a pilot study

Abdul Aziz, A., Abu Kasim, N.H., Ramasindarum, C., Mohamad Yusof, M.Y.P., Paiizi, M., Ahmad, R.

Ann Dent, 2011;18(1):1-7.
MyJurnal

The aim of this study was to assess the wear of tungsten carbide burs and round rotary diamond instruments through measurements of rake angle and visual observations respectively under a field emission scanning electron microscope. Sixty short and long head pear-shaped tungsten carbide burs and 18 round rotary diamond instruments that had been used to complete < 5, > 5 and > 10 cavity preparations (n=10/group) were selected from the 3rd and 4th year dental students, Faculty of Dentistry, University of Malaya. There were two control groups consisting of long and short tungsten carbide burs of ten each. Two-way ANOVA was used to analyse the rake angle data. The data from the two control groups were collectively analysed following multiple paired t-test (p>.05) which showed no significant difference between the two types of tungsten carbide bur (short and long head). The mean rake angle of the control group was significantly higher (p < .05) compared to the < 5, > 5 and > 10 cavity preparation groups. The rake angle of the > 10 cavity preparation group was significantly lower than the other two test groups (p < .05). Round rotary diamond instruments in the < 5 cavity preparation group showed intact diamond particles with distinct cutting facets comparable to the control group. However, diamonds instruments in the > 5 and > 10 cavity preparation groups showed blunt diamond particles. In conclusion, wear of tungsten carbide burs and round rotary diamond instruments were evident after repeated use. Wear was more pronounced when instruments were used to prepare more than ten cavities.

Matched MeSH terms: Microscopy, Electron, Scanning
Fulltext Influence of scaler tip design on root surface roughness, tooth substance loss and patients' pain perception: an in vitro and a randomised clinical trial

Abdul Hayei NA, Yahya NA, Safii SH, Saub R, Vaithilingam RD, Baharuddin NA

BMC Oral Health, 2021 03 31;21(1):169.
PMID: 33789646 DOI: 10.1186/s12903-021-01540-0

BACKGROUND: The influence of scaler tip design on root surface roughness, tooth substance loss and patients' pain perception is investigated.
METHODS: This article was divided into the following parts: Part 1 Surface roughness and substance loss: an in vitro study, which involves intact extracted teeth sectioned and treated using a piezoelectric ultrasonic device (PM200 EMS Piezon, Switzerland) with a conventional scaler tip (FS-407) and a Perio Slim (PS) scaler tip (Perio Slim DS-016A). All sectioned samples for tooth surface roughness (n = 20) and tooth substance loss (n = 46) analyses were measured and compared using a 3D surface texture analyser and scanning electron microscope (SEM) respectively, at baseline and following scaling. Part 2 Pain Perception: a clinical study, which was a split mouth study design including 30 participants with gingivitis and/or mild chronic periodontitis; treated with supra-gingival scaling from teeth #13 to #23. Subjects were randomised to group A or group B. Group A was treated first with PS scaler tips, whereas group B was treated first with conventional scaler tips. Pain perception was recorded using the visual analogue scale (VAS).
RESULTS: In vitro study: both scaler tips caused significant reduction in root substance roughness after scaling (p 0.05) was observed. The PS scaler tip caused statistically significantly less root substance loss (p

Matched MeSH terms: Microscopy, Electron, Scanning
Production and characterization of the defatted oil palm shell nanoparticles

Abdul Khalil HPS, Md. Sohrab Hossain, Nur Amiranajwa AS, Nurul Fazita MR, Mohamad Haafiz MK, Suraya N, et al.

Sains Malaysiana, 2016;45:833-839.

This present study was conducted to produce defatted oil palm shell (OPS) nanoparticles. Wherein, the OPS nanoparticles
were defatted by solvent extraction method. Several analytical methods including transmission electron microscope (TEM),
X-ray diffraction (XRD), particle size analyzer, scanning electron microscope (SEM), SEM energy dispersive X-ray (SEM-EDX)
and thermal gravimetric analyzer (TGA) were used to characterize the untreated and defatted OPS nanoparticles. It was
found that 75.3% OPS particles were converted into nanoparticles during ball milling. The obtained OPS nanoparticles had
smaller surface area with angular, irregular and crushed shapes under SEM view. The defatted OPS nanoparticles did not
show any agglomeration during TEM observation. However, the untreated OPS nanoparticles had higher decomposition
temperature as compared to the defatted OPS nanoparticles. Based on the characterization results of the OPS nanoparticles,
it is evident that the defatted OPS nanoparticles has the potentiality to be used as filler in biocomposites

Matched MeSH terms: Microscopy, Electron, Scanning
Effects of changes in chemical and structural characteristic of ammonia fibre expansion (AFEX) pretreated oil palm empty fruit bunch fibre on enzymatic saccharification and fermentability for biohydrogen

Abdul PM, Jahim JM, Harun S, Markom M, Lutpi NA, Hassan O, et al.

Bioresour Technol, 2016 Jul;211:200-8.
PMID: 27017130 DOI: 10.1016/j.biortech.2016.02.135

Oil palm empty fruit bunch (OPEFB) fibre is widely available in Southeast Asian countries and found to have 60% (w/w) sugar components. OPEFB was pretreated using the ammonia fibre expansion (AFEX) method and characterised physically by the Fourier transform infrared spectroscopy, X-ray diffraction and scanning electron microscopy. The results show that there were significant structural changes in OPEFB after the pretreatment step, and the sugar yield after enzymatic hydrolysis using a cocktail of Cellic Ctec2® and Cellic Htec2® increased from 0.15gg(-1) of OPEFB in the raw untreated OPEFB sample to 0.53gg(-1) of OPEFB in AFEX-pretreated OPEFB (i.e. almost a fourfold increase in sugar conversion), which enhances the economic value of OPEFB. A biohydrogen fermentability test of this hydrolysate was carried out using a locally isolated bacterium, Enterobacter sp. KBH6958. The biohydrogen yield after 72h of fermentation was 1.68mol H2 per mol sugar. Butyrate, ethanol, and acetate were the major metabolites.

Matched MeSH terms: Microscopy, Electron, Scanning
Fulltext Extraction and Characterization of Cellulose Nanocrystals from Tea Leaf Waste Fibers

Abdul Rahman NH, Chieng BW, Ibrahim NA, Abdul Rahman N

Polymers (Basel), 2017 Nov 07;9(11).
PMID: 30965890 DOI: 10.3390/polym9110588

The aim was to explore the utilization of tea leaf waste fibers (TLWF) as a source for the production of cellulose nanocrystals (CNC). TLWF was first treated with alkaline, followed by bleaching before being hydrolyzed with concentrated sulfuric acid. The materials attained after each step of chemical treatments were characterized and their chemical compositions were studied. The structure analysis was examined by Fourier transform infrared (FTIR) spectroscopy and X-ray diffraction (XRD). From FTIR analysis, two peaks at 1716 and 1207 cm-1-which represent C=O stretching and C⁻O stretching, respectively-disappeared in the spectra after the alkaline and bleaching treatments indicated that hemicellulose and lignin were almost entirely discarded from the fiber. The surface morphology of TLWF before and after chemical treatments was investigated by scanning electron microscopy (SEM) while the dimension of CNC was determined by transmission electron microscopy (TEM). The extraction of CNC increased the surface roughness and the crystallinity index of fiber from 41.5% to 83.1%. Morphological characterization from TEM revealed the appearance of needle-like shaped CNCs with average diameter of 7.97 nm. The promising results from all the analyses justify TLWF as a principal source of natural materials which can produce CNC.

Matched MeSH terms: Microscopy, Electron, Scanning
Fulltext Carnauba Wax/Halloysite Nanotube with Improved Anti-Wetting and Permeability of Hydrophobic PVDF Membrane via DCMD

AbdulKadir WAFW, Ahmad AL, Boon Seng O

Membranes (Basel), 2021 Mar 23;11(3).
PMID: 33807017 DOI: 10.3390/membranes11030228

The hydrophobic membranes have been widely explored to meet the membrane characteristics for the membrane distillation (MD) process. Inorganic metal oxide nanoparticles have been used to improve the membrane hydrophobicity, but limited studies have used nano clay particles. This study introduces halloysite nanotube (HNT) as an alternative material to synthesis a hydrophobic poly(vinylidene fluoride) (PVDF)-HNT membrane. The PVDF membranes were fabricated using functionalized HNTs (e.g., carnauba wax and 1H,1H,2H,2H-perfluorooctyl-trichlorosilane (FOTS)). The results were determined by Fourier transform infrared-attenuated total reflection, scanning electron microscope, goniometer and porometer to determine the desired hydrophobic membrane for direct contact membrane distillation (DCMD). The addition of FOTS-HNT (fs-HNT) and carnauba wax-HNT (fw-HNT) in the PVDF membrane enhanced the water contact angle (CA) to 127° and 137°, respectively. The presence of fw-HNT in the PVDF membrane exhibited higher liquid entry pressure (LEP) (2.64 bar) compared to fs-HNT in the membrane matrix (1.44 bar). The PVDF/fw-HNT membrane (Pfw-HNT) obtained the highest flux of 7.24 L/m2h with 99.9% salt removal. A stable permeability in the Pfw-HNT membrane was obtained throughout 16 h of DCMD. The incorporation of fw-HNT in the PVDF membrane had improved the anti-wetting properties and the membrane performance with the anti-fouling effect.

Matched MeSH terms: Microscopy, Electron, Scanning
Fulltext Effects of salivary pH on coating durability of two different aesthetic archwire coatings under a simulated intraoral environment

Abdulkader YC, Kamaruddin AF, Mydin RBSMN

Saudi Dent J, 2020 Sep;32(6):306-313.
PMID: 32874071 DOI: 10.1016/j.sdentj.2019.09.010

Objectives: This study compared the effects of normal salivary pH, and acidic pH found in patients with poor oral hygiene, on the durability of aesthetic archwire coated with epoxy resin and polytetrafluoroethylene (PTFE).
Methods: The posterior parts of the archwires were sectioned into 20 mm segments (N = 102) and divided among six groups. Four groups were treated with different pH levels and two served as controls. The specimens were immersed in individual test tubes containing 10 ml of artificial saliva adjusted to a pH of 6.75 or 3.5. The tubes were sealed and stored in a 37 °C water bath for 28 days. After 28 days, the specimens were ligated to brackets embedded in an acrylic block and subjected to mechanical stress using an electronic toothbrush for 210 s. The specimens were photographed, and images were measured for coating loss using AutoCAD® software. Surface morphology was observed using a scanning electron microscope (SEM).
Results: Significant coating loss (p 

Matched MeSH terms: Microscopy, Electron, Scanning
Response surface methodology analysis of the photocatalytic removal of Methylene Blue using bismuth vanadate prepared via polyol route

Abdullah AH, Moey HJ, Yusof NA

J Environ Sci (China), 2012;24(9):1694-701.
PMID: 23520879

Visible-light driven photocatalyst bismuth vanadate (BiVO4) photocatalyst was synthesized by the polyol route using ethylene glycol. The precipitate was washed, dried and calcined at 450 degrees C for 3 hr. The sample was characterized by X-ray diffractometry (XRD), field emission scanning electron microscopy (FE-SEM), zeta potential, surface area (BET method) and band gap energy via diffuse reflectance spectroscopy (DRS). The synthesized BiVO4 has a monoclinic phase with a surface area of 4.3 m2/g and a band gap energy of 2.46 eV. A majority of the particles were in the range of 90-130 nm as obtained from the particle size distribution histrogram. The efficiency of the sample as a visible-light driven photocatalyst was examined by photodegrading Methylene Blue (MB). The effects of some operational photodegradation parameters such as mass loading, initial dye concentration and pH were also examined. Experimental design methodology was applied by response surface modeling and optimization of the removal of MB. The multivariate experimental design was employed to develop a quadratic model as a functional relationship between the percentage removal of MB and three experimental factors (BiVO4 loading, MB initial concentration and pH). The percentage removal of MB approached 67.21% under optimized conditions. In addition, a satisfactory goodness-of-fit was achieved between the,predictive and the experimental results.

Matched MeSH terms: Microscopy, Electron, Scanning

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