In this study, we synthesized covalently functionalized graphene nanoplatelet (GNP) aqueous suspensions that are highly stable and environmentally friendly for use as coolants in heat transfer systems. We evaluated the heat transfer and hydrodynamic properties of these nano-coolants flowing through a horizontal stainless steel tube subjected to a uniform heat flux at its outer surface. The GNPs functionalized with clove buds using the one-pot technique. We characterized the clove-treated GNPs (CGNPs) using X-ray photoelectron spectroscopy (XPS) and transmission electron microscopy (TEM). We then dispersed the CGNPs in distilled water at three particle concentrations (0.025, 0.075 and 0.1wt%) in order to prepare the CGNP-water nanofluids (nano-coolants). We used ultraviolet-visible (UV-vis) spectroscopy to examine the stability and solubility of the CGNPs in the distilled water. There is significant enhancement in thermo-physical properties of CGNPs nanofluids relative those for distilled water. We validated our experimental set-up by comparing the friction factor and Nusselt number for distilled water obtained from experiments with those determined from empirical correlations, indeed, our experimental set-up is reliable and produces results with reasonable accuracy. We conducted heat transfer experiments for the CGNP-water nano-coolants flowing through the horizontal heated tube in fully developed turbulent condition. Our results are indeed promising since there is a significant enhancement in the Nusselt number and convective heat transfer coefficient for the CGNP-water nanofluids, with only a negligible increase in the friction factor and pumping power. More importantly, we found that there is a significant increase in the performance index, which is a positive indicator that our nanofluids have potential to substitute conventional coolants in heat transfer systems because of their overall thermal performance and energy savings benefits.
The habitats of Eurycoma longifolia Jack, a slender tree, are jungles in Malaysia and Indonesia. It belongs to the family Simaroubaceae and is a source of quassinoids with anabolic, antimalarial and cytostatic activity. In this study, conducted during 2008 in Mae Sot, Thailand, a standardized extract of E. longifolia containing three major quassinoids, eurycomanone (1), 13,21-dihydroeurycomanone (2) and 13alpha(21)-epoxyeurycomanone (3) was evaluated for antiplasmodial activity against Plasmodium falciparum and its activity has been compared with that of artemisinin, using 38 fresh parasite isolates and assessment of inhibition of schizont maturation. The IC(50), IC(90) and IC(99) values for artemisinin were 4.30, 45.48 and 310.97 microg/l, and those for the root extract from E. longifolia 14.72, 139.65 and 874.15 microg/l respectively. The GMCOC for artemisinin was 337.81 mug/l, and for the plant extract it was 807.41 microg/l. The log-concentration probit regressions were parallel. The inhibitory activity of the E. longifolia extract was higher than that expected from the three quassinoids isolated from the plant, suggesting synergism between the quassinoids or the presence of other unidentified compounds.
The plant Catharanthus roseus is a rich source of terpenoid indole alkaloids (TIA). Some of the TIA are important as antihypertensive (ajmalicine) and anticancer (vinblastine and vincristine) drugs. However, production of the latter is very low in the plant. Therefore, in vitro plant cell cultures have been considered as a potential supply of these chemicals or their precursors. Some monomeric alkaloids can be produced by plant cell cultures, but not on a level feasible for commercialization, despite extensive studies on this plant that deepened the understanding of the TIA biosynthesis and its regulation. In order to analyze the metabolites in C. roseus cell cultures, this chapter presents the method of TIA, carotenoids, and phytosterols analyses. Furthermore, an NMR-based metabolomics approach to study C. roseus cell culture is described.
Colloidal gas aphron dispersions (CGAs) can be described as a system of microbubbles suspended homogenously in a liquid matrix. This work examines the performance of CGAs in comparison to surfactant solutions for washing low levels of arsenic from an iron rich soil. Sodium Dodecyl Sulfate (SDS) and saponin, a biodegradable surfactant, obtained from Sapindus mukorossi or soapnut fruit were used for generating CGAs and solutions for soil washing. Column washing experiments were performed in down-flow and up flow modes at a soil pH of 5 and 6 using varying concentration of SDS and soapnut solutions as well as CGAs. Soapnut CGAs removed more than 70% arsenic while SDS CGAs removed up to 55% arsenic from the soil columns in the soil pH range of 5-6. CGAs and solutions showed comparable performances in all the cases. CGAs were more economical since it contains 35% of air by volume, thereby requiring less surfactant. Micellar solubilization and low pH of soapnut facilitated arsenic desorption from soil column. FT-IR analysis of effluent suggested that soapnut solution did not interact chemically with arsenic thereby facilitating the recovery of soapnut solution by precipitating the arsenic. Damage to soil was minimal arsenic confirmed by metal dissolution from soil surface and SEM micrograph.
Polyacrylamide (PAM), a commonly used organic synthetic flocculant, is known to have high reduction in turbidity treatment. However, PAM is not readily degradable. In this paper, pectin as a biopolymeric flocculant is used. The objectives are (i) to determine the characteristics of both flocculants (ii) to optimize the treatment processes of both flocculants in synthetic turbid waste water. The results obtained indicated that pectin has a lower average molecular weight at 1.63 x 10(5) and PAM at 6.00 x 10(7). However, the thermal degradation results showed that the onset temperature for pectin is at 165.58 degrees C, while the highest onset temperature obtained for PAM is at 235.39 degrees C. The optimum treatment conditions for the biopolymeric flocculant for flocculating activity was at pH 3, cation concentration at 0.55 mM, and pectin concentration at 3 mg/L. In contrast, PAM was at pH 4, cation concentration >0.05 mM and PAM concentration between 13 and 30 mg/L.
Objectives: This study describes the clinical outcomes and therapeutic drug monitoring (TDM) following posaconazole suspension pre-emptive therapy in lung transplant (LTx) recipients.
Methods: This was a single-centre, retrospective cohort study evaluating posaconazole suspension pre-emptive therapy in LTx recipients between January 2009 and December 2015.
Results: Forty-two LTx recipients were prescribed posaconazole suspension pre-emptively. Aspergillus fumigatus was the most commonly isolated fungal organism. Of the patients receiving posaconazole suspension as the initial antifungal post-LTx, 93% had eradication of colonization at 6 months after commencing therapy. In contrast, only 61% had eradication of fungal colonization when posaconazole suspension was administered following initial therapy with voriconazole. Posaconazole suspension appeared to be well tolerated, although one case was curtailed following concern about abnormal liver function and another due to nausea/vomiting. TDM was performed in 37 patients. The initial median (IQR) trough plasma concentration ( C min ) following 400 mg twice-daily posaconazole suspension was 0.78 (0.46-1.19) mg/L. Doses beyond 800 mg daily did not appear to result in a higher median C min.
Conclusions: Early initiation of posaconazole suspension pre-emptive therapy in LTx recipients appears to be well tolerated and may potentially afford favourable clinical outcomes.
In this paper, Polyimide/Montmorillonite Nanocomposites (PI/MMT NCs), based on aromatic diamine (4-Aminophenyl sulfone) (APS) and aromatic dianhydride (3,3',4,4'-benzophenonetetracarboxylic dianhydride) (BTDA) were prepared using in situ polymerization and solution-dispersion techniques. The prepared PI/MMT NCs films were characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), transmission electron microscopy (TEM) and thermogravimetric analysis (TGA). The XRD results showed that at the content of 1.0 wt % Organo Montmorillonite (OMMT) for two techniques and 3.0 wt % OMMT for the in situ polymerization technique, the OMMT was well-intercalated, exfoliated and dispersed into polyimide matrix. The OMMT agglomerated when its amount exceeded 10 wt % and 3.0 wt % for solution-dispersion and in situ polymerization techniques respectively. These results were confirmed by the TEM images of the prepared PI/MMT NCs. The TGA thermograms indicated that thermal stability of prepared PI/MMT NCs were increased with the increase of loading that, the effect is higher for the samples prepared by in situ polymerization technique.
Even though microalgal biomass is leading the third generation biofuel research, significant effort is required to establish an economically viable commercial-scale microalgal biofuel production system. Whilst a significant amount of work has been reported on large-scale cultivation of microalgae using photo-bioreactors and pond systems, research focus on establishing high performance downstream dewatering operations for large-scale processing under optimal economy is limited. The enormous amount of energy and associated cost required for dewatering large-volume microalgal cultures has been the primary hindrance to the development of the needed biomass quantity for industrial-scale microalgal biofuels production. The extremely dilute nature of large-volume microalgal suspension and the small size of microalgae cells in suspension create a significant processing cost during dewatering and this has raised major concerns towards the economic success of commercial-scale microalgal biofuel production as an alternative to conventional petroleum fuels. This article reports an effective framework to assess the performance of different dewatering technologies as the basis to establish an effective two-stage dewatering system. Bioflocculation coupled with tangential flow filtration (TFF) emerged a promising technique with total energy input of 0.041 kWh, 0.05 kg CO2 emissions and a cost of $ 0.0043 for producing 1 kg of microalgae biomass. A streamlined process for operational analysis of two-stage microalgae dewatering technique, encompassing energy input, carbon dioxide emission, and process cost, is presented.
The purpose of this study is to determine whether isolated suspension mouse peripheral mononucleated blood cells have the potential to differentiate into two distinct types of cells, i.e., osteoblasts and osteoclasts.
Unilamellar liposomes composed of dipalmitoylphosphatidylcholine (DPPC) were prepared by the reverse-phase
evaporation method and extrusion through a polycarbonate membrane filter. Liposomes at 0.7 mg/mL lipid concentration
in deionized water were exposed to gamma irradiation at a dose in the range 0.5 to 25 kGy. Gamma irradiation of
liposomes resulted in the degradation of DPPC lipids into free fatty acids, lysophosphatidylcholine and 1,2-palmitoylphosphatidic
acid (DPPA). The effect of gamma irradiation towards the physical stability of liposomes was investigated
by means of dynamic light scattering (DLS), transmission electron microscopy (TEM) and zeta potential analysis. From
the DLS analysis, no significant changes were observed in the hydrodynamic size of liposomes. TEM images indicate that
the liposomes surface became smoother and rounder as higher irradiation doses were applied. Zeta potential analysis
showed that gamma irradiation of DPPC liposomes at radiation doses as low as 0.5 kGy resulted in a drastic rise in the
magnitude of the zeta potential. The results also demonstrate that gamma irradiation of liposomes suspension enhanced
the overall stability of liposomes. Hence, it can be concluded that gamma irradiation on DPPC liposomes may potentially
produce liposomes with higher stability.
Citrus canker caused by Xanthomonas citri subsp. citri is a disease affecting the yield and fruit quality of lime (Citrus aurantiifolia). This research investigated endophytic bacteria obtained from six healthy Citrus spp. to inhibit the pathogen and to control citrus canker on lime plants. Numbers of the endophytic bacteria isolated from C. aurantifolia, C. hystrix, C. maxima, C. nobilis, C. reticulata and C. sinensis were 28, 25, 29, 42, 12 and 34 isolates, respectively. The selected endophytic bacteria that were effective against X. citri subsp. citri were Bacillus amyloliquefaciens LE109, B. subtilis LE24 and B. tequilensis PO80. The optimum culture medium for an antagonistic effect on the pathogen in B. amyloliquefaciens LE109 and B. tequilensis PO80 was yeast extract peptone dextrose broth, and in B. subtilis LE24 was modified soluble starch broth. To control citrus canker in lime, young expanded leaves of lime plants were aseptically punctured and inoculated with 30 μl of bacterial suspension of the pathogen (108 CFU/ml in 0.85% NaCl) per punctured location. After the pathogenic inoculation for 24 h, the leaves were then inoculated with 30 μl of the selected endophytic bacteria (108 CFU/ml in 0.85% NaCl), and treated with 30 μl of the culture media containing bioactive compounds produced by the selected endophytic bacteria. The leaves inoculated with cell suspensions of B. amyloliquefaciens LE109 or B. subtilis LE24 could completely control citrus canker. However, the leaves inoculated with B. tequilensis PO80 displayed 10% disease incidence. Additionally, the leaves treated with the crude bioactive compounds of B. amyloliquefaciens LE109 or B. subtilis LE24 could completely control citrus canker. Notably, the leaves treated with the crude bioactive compounds of B. tequilensis PO80 displayed 5% disease incidence. The results of this study showed that the Bacillus strains play important roles in the biocontrol of citrus canker in lime.
Red-fleshed dragon fruit (Hylocereus polyrhizus [Weber] Britton & Rose) is a newly introduced and potential crop in the Malaysian fruit industry. Besides its nutritious value, the fruit is being promoted as a health crop throughout Southeast Asia. In April of 2007, a new disease was observed in major plantations of H. polyrhizus throughout five states (Kelantan, Melaka, Negeri Sembilan, Penang, and Perak) in Malaysia with 41 and 25% disease incidence and severity, respectively. Stems of H. polyrhizus showed spots or small, circular, faint pink-to-beige necrotic lesions that generally coalesced as symptoms progressed. Symptom margins of diseased stem samples were surface sterilized with a 70% alcohol swab, cut into small blocks (1.5 × 1.5 × 1.5 cm), soaked in 1% sodium hypochlorite (NaOCI) for 3 min, and rinsed in several changes of sterile distilled water (each 1 min). The surface-sterilized tissues were placed onto potato dextrose agar (PDA) and incubated under alternating 12-h daylight and black light for 7 days. A fungus was consistently isolated from the stems of symptomatic H. polyrhizus and identified as Curvularia lunata (Wakker) Beodijn (1-3) that showed pale brown multicelled conidia (phragmoconidia; three to five celled) that formed apically through a pore (poroconidia) in sympodially, elongating, geniculated conidiophores. Conidia are relatively fusiform, cylindrical, or slightly curved, with one of the central cells being larger and darker (26.15 ± 0.05 μm). All 25 isolates of C. lunata obtained from diseased H. polyrhizus are deposited at the Culture Collection Unit, Universiti Sains Malaysia and available on request. Isolates were tested for pathogenicity by injecting conidial suspensions (1 × 106 conidia/ml) and pricking colonized toothpicks on 25 healthy H. polyrhizus stems. Controls were treated with sterile distilled water and noncolonized toothpicks. All inoculated plants and controls were placed in a greenhouse with day and night temperatures of 30 to 35°C and 23 to 30°C, respectively. Development of external symptoms on inoculated plants was observed continuously every 2 days for 2 weeks. Two weeks after inoculation, all plants inoculated with all isolates of C. lunata developed stem lesions similar to those observed in the field. No symptoms were observed on the control plants and all remained healthy. C. lunata was reisolated from 88% of the inoculated stems, completing Koch's postulates. The pathogenicity test was repeated with the same results. To our knowledge, this is the first report of C. lunata causing a disease on H. polyrhizus. References: (1) M. B. Ellis. Dematiaceous Hyphomycetes. Commonwealth Mycological Institute, Kew, Surrey, England, 1971. (2) R. R. Nelson and F. A. Hassis. Mycologia 56:316, 1964. (3) C. V. Subramanian. Fungi Imperfecti from Madras V. Curvularia. Proc. Indian Acad. Sci. 38:27, 1955.
Rambutan (Nephelium lappaceum L.) is among the tropical fruit grown in Malaysia and the demand for export rose in 2011. A fruit rot was observed between August and December 2011 from several areas in the states of Pulau Pinang and Perak, Malaysia. The symptoms initially appeared as light brown, water-soaked lesions that developed first in the pericarp and pulp, later enlarging and becoming dark brown. Greyish brown mycelia were observed on infected areas that turned yellowish at later stages of infection. Gliocephalotrichum bacillisporum was isolated from infected fruit by surface sterilization techniques. Conidia were mass-transferred onto potato dexstrose agar (PDA) plates and incubated at 27 ± 1°C. Tissue pieces (5 × 5 mm) excised from the margins between infected and healthy areas were then surface sterilized in 1% sodium hypochlorite for 3 to 5 min before being rinsed with distilled water, plated on PDA, and incubated at 27 ± 1°C for 7 days. Ten isolates of G. bacillisporum were obtained. Colonies on PDA were initially white before turning yellow with a feathery appearance. Microscopic characteristics on carnation leaf agar (CLA) consisted of hyaline conidia that were slightly ellipsoid to bacilliform with rounded apex ranging from 6.0 to 8.5 μm long and 2.0 to 2.5 μm wide. Conidiophores (70 to 130 μm long) were mostly single arising from large hypha approximately 13 to 16 μm. The conidiogenous structures were mostly quadriverticillate with dense, short, penicillate branches. The phialides were cylindrical and finger-like. Chlamydospores were present singly, in groups of 2 to 4, or in occasionally branched short chains and were brown in color with thick walls ranging from 11 to 13 μm. The cultural and morphological characteristics of G. bacillisporum isolates in the present study were very similar to previously published descriptions (1) except the conidiophores formed without sterile stipe extensions. All the G. bacillisporum isolates were deposited in culture collection at the Plant Pathology Lab, University Sains Malaysia, Penang. Molecular identification was accomplished from the ITS regions using ITS1 and ITS2 primers, and the β-tubulin gene using Bt2a and Bt2b primers (2). BLAST results from the ITS regions showed a 98 to 99% similarity with sequences of G. bacillisporum isolates reported in GenBank. Accession numbers of G. bacillisporum ITS regions: JX484850, JX484852, JX484853, JX484856, JX484858, JX484860, JX484862, JX484866, JX484867, and JX484868. The identity of G. bacillisporum isolates infecting rambutan was further confirmed by β-tubulin sequences (KC683909, KC683911, KC683912, KC683916, KC683919, KC683920, KC683923, KC683926, and KC683927), which showed 92 to 95% similarity with sequences of G. bacillisporum. Pathogenicity tests were also performed using mycelial plug (5 mm) and sprayed conidial suspensions (20 μl suspension of 106 conidia/ml) prepared from 7-day-old cultures. Inoculated fruits were incubated at 27 ± 1°C and after 10 days, similar rotting symptoms appeared on the fruit surface. The pathogen was reisolated from fruit rot lesions, thus fulfilling Koch's postulates, and tests were repeated twice. To our knowledge, this is the first report of G. bacillisporum causing fruit rot of rambutan (N. lappaceum L.) in Malaysia. References: (1) C. Decock et al. Mycologia 98:488, 2006. (2) N. L. Glass and G. C. Donaldson. Appl. Environ Microbiol. 61:1323, 1995.
Mangosteen (Garcinia mangostana L.) is a tropical evergreen tree that produces one of the most prized tropical fruits, commonly known as the "Queen of the Fruits.″ Mangosteen has the potential to occupy a rapidly expanding niche market in Hawaii. In October 2009, a disease was observed that produced brown leaf spots and blotches surrounded by bright yellow halos at a mangosteen orchard located in Hakalau, Hawaii (19° 53' 49″ N, 155° 7' 35″ W). Recently transplanted 10+ year old trees were 95 to 100% infected. Pieces of infected leaves and stems were surface-sterilized, plated on potato dextrose agar (PDA), and incubated at 24°C ± 1°C for 21 days. The fungus growing on PDA was pale buff with sparse aerial mycelium and acervuli containing black, slimy spore masses. Single spore isolates were used for the morphological characteristics and molecular analysis. Conidia were 5-celled. Apical and basal cells were hyaline; the three median cells were umber to olivaceous. Conidia (n = 50) were 24.3 ± 0.2 × 7.5 ± 0.1 μm, with apical appendages, typically three, averaging 24.3 ± 0.4 μm long, and a basal appendage averaging 6.7 ± 0.2 μm long. DNA sequences were obtained from the β-tubulin gene and the internal transcribed spacer (ITS1 and ITS2) and 5.8S regions of the rDNA to confirm the identification. The morphological descriptions and measurements were similar to P. virgatula (Kleb.) Steyaert (1). Although sequence data of the ITS region (GenBank Accession No. JN542546) supports the identity of the fungus as P. virgatula, the taxonomy of this genus remains confused since there are only a few type cultures, so it is impossible to use sequences in GenBank to reliably clarify species names (2). To confirm pathogenicity, six leaves of two 3-year-old seedlings were inoculated. Seven-day-old cultures grown on 10% V8 agar at 24°C under continuous fluorescent lighting were used for inoculations. The inoculum consisted of spore suspensions in sterile distilled water adjusted to 6 × 105 conidia/ml. Using a fine haired paint brush, the inoculum was brushed onto the youngest leaves, while sterile distilled water was used as the control. The plants were incubated in a clear plastic bag placed on the laboratory bench at 24°C for 48 hours, then placed on a greenhouse bench and observed weekly for symptoms. After 14 days, leaf spots ranging in size from pinpoint to 5.4 mm in diameter with a distinctive yellow halo were present. Within 35 days, the leaf spots enlarged to leaf blotches ranging in size from 11.5 × 13.3 mm up to 28.3 × 34.6 mm with brown centers and a distinctive yellow halo identical to the field symptoms. A Pestalotiopsis sp. identical to that used to inoculate the seedlings was recovered from the leaf spots and blotches, confirming Koch's postulates. The experiment was repeated twice. Pestalotiopsis leaf blight has been reported in other countries growing mangosteen, including Thailand, Malaysia, and North Queensland, Australia (3). However, to our knowledge, this is the first report of a Pestalotiopsis sp. causing a disease on mangosteen in Hawaii. Although this disease is considered a minor problem in the literature (3), effective management practices should be established to avoid potential production losses. References: (1) E. F. Guba. Monograph of Pestalotia and Monochaetia. Harvard University Press, Cambridge, MA. 1961. (2) S. S. N. Maharachchikumbura et al. Fungal Div. 50:167, 2011. (3) R. C. Ploetz. Diseases of Tropical Fruit Crops. CABI Publishing. Wallingford, Oxfordshire, UK, 2003.
In December 2008, infected leaves of Trichosanthes cucumerina were observed on commercial cucurbit farms located in Pontian, Johor (south of West Malaysia). Bright yellow and small necrotic lesions were observed on the adaxial surface of the leaves, whereas sporangiophores were observed on pale yellowish brown-to-brown lesions on the abaxial surface. The length and width of the sporangia ranged from 19 to 36 μm (28.6) and 11 to 23 μm (17.6), respectively. The length of the sporangiophores ranged from 310 to 450 μm, with an average length of 380 μm. The pathogen was identified as Pseudoperonospora cubensis on the basis of the morphological criteria described by Palti and Cohen (2). To confirm the morphological findings, DNA was extracted from symptomatic tissue and the internal transcribed spacer (ITS) region was PCR amplified using primers ITS5-P2 and ITS4 (3). The appropriate-sized amplicon was gel excised and column purified and then submitted for direct sequencing. The resulting 802 bp amplified ITS region was 100% identical to published P. cubensis sequences (GenBank Accession Nos. EU876603, EU876584, and AY198306). This sequence was deposited with NCBI GenBank under the Accession No. GU233293. In this study, pathogenicity tests were conducted using detached leaf disc assays (1) and a P. cubensis isolate obtained from T. cucumerina. For this purpose, leaf discs were excised from 6- to 8-week-old leaves of T. cucumerina using a 20-mm cork borer. Five leaf discs were placed with their abaxial surface facing upward on moist filter paper in petri dishes. Each of four leaf discs was inoculated with four 10-μl droplets of a 1 × 105 per ml sporangial suspension, whereas the fifth disc was inoculated with water droplets and served as a control. Three replications were completed. The leaf discs were placed in darkness at 14 ± 2°C for 24 h and subsequently incubated with a 12-h photoperiod. After 10 days, sporulation was observed on the sporangia-inoculated leaf discs with similar morphological features to the initial field samples. To our knowledge, this is the first report of P. cubensis causing downy mildew of T. cucumerina in Malaysia. References: (1) A. Lebeda and M. P. Widrlechner. J. Plant Dis. Prot. 110:337, 2003. (2) J. Palti and Y. Cohen. Phytoparasitica 8:109, 1980. (3) H. Voglmayr and O. Constantinescu. Mycol. Res. 112:487, 2008.
On May 9, 2013, symptoms reminiscent of bacterial leaf streak (BLS) caused by Xanthomonas oryzae pv. oryzicola were observed on rice plants at the panicle emergence stage at Musenyi, Gihanga, and Rugombo fields in Burundi. Affected leaves showed water-soaked translucent lesions and yellow-brown to black streaks, sometimes with visible exudates on leaf surfaces. Symptomatic leaves were ground in sterile water and the suspensions obtained were subjected to a multiplex PCR assay diagnostic for X. oryzae pathovars (3). Three DNA fragments (331, 691, and 945 bp) corresponding to X. oryzae pv. oryzicola were observed after agarose gel electrophoresis. Single bacterial colonies were then isolated from surface-sterilized, infected leaves after grinding in sterile water and plating of 10-fold dilutions of the cell suspension on semi-selective PSA medium (4). After incubation at 28°C for 5 days, each of four independent cultures yielded single yellow, mucoid Xanthomonas-like colonies (named Bur_1, Bur_2, Bur_6, and Bur_7) that resembled the positive control strain MAI10 (1). These strains originated from Musenyi (Bur_1), Gihanga (Bur_2), and Rugumbo (Bur_6 and Bur_7). Multiplex PCR assays on the four putative X. oryzae pv. oryzicola strains yielded the three diagnostic DNA fragments mentioned above. All strains were further analyzed by sequence analysis of portions of the gyrB gene using the universal primers gyrB1-F and gyrB1-R for PCR amplification (5). The 762-bp DNA fragment was identical to gyrB sequences from the Asian X. oryzae pv. oryzicola strains BLS256 (Philippines), ICMP 12013 (China), LMG 797 and NCPPB 2921 (both Malaysia), and from the African strain MAI3 (Mali) (2). The partial nucleotide sequence of the gyrB gene of Bur_1 was submitted to GenBank (Accession No. KJ801400). Pathogenicity tests were performed on greenhouse-grown 4-week-old rice plants of the cvs. Nipponbare, Azucena, IRBB 1, IRBB 2, IRBB 3, IRBB 7, FKR 14, PNA64F4-56, TCS 10, Gigante, and Adny 11. Bacterial cultures were grown overnight in PSA medium and re-suspended in sterile water (1 × 108 CFU/ml). Plants were inoculated with bacterial suspensions either by spraying or by leaf infiltration (1). For spray inoculation, four plants per accession and strain were used while three leaves per plant and four plants per accession and strain were inoculated by tissue infiltration. After 15 days of incubation in a BSL-3 containment facility (27 ± 1°C with a 12-h photoperiod), the spray-inoculated plants showed water-soaked lesions with yellow exudates identical to those seen in the field. For syringe-infiltrated leaves, the same symptoms were observed at the infiltrated leaf area. Re-isolation of bacteria from symptomatic leaves yielded colonies with the typical Xanthomonas morphology that were confirmed by multiplex PCR to be X. oryzae pv. oryzicola, thus fulfilling Koch's postulates. Bur_1 has been deposited in the Collection Française de Bactéries Phytopathogènes as strain CFBP 8170 ( http://www.angers-nantes.inra.fr/cfbp/ ). To our knowledge, this is the first report of X. oryzae pv. oryzicola causing bacterial leaf streak on rice in Burundi. Further surveys will help to assess its importance in the country. References: (1) C. Gonzalez et al., Mol. Plant Microbe Interact. 20:534, 2007. (2) A. Hajri et al. Mol. Plant Pathol. 13:288, 2012. (3) J. M. Lang et al. Plant Dis. 94:311, 2010. (4) L. Poulin et al. Plant Dis. 98:1423, 2014. (5) J. M. Young et al. Syst. Appl. Microbiol. 31:366, 2008.
Nanostructured lipid carriers (NLCs) loaded with lopinavir (LPV) were prepared by the high-shear homogenization method. The LPV-NLCs formulations were freeze-dried using trehalose as a cryoprotectant. In vitro release studies in simulated gastric fluid (pH 1.2) and simulated intestinal fluid (pH 6.8) showed a burst release. The optimized freeze-dried formulation (LPV-NLC-7-Tres) had a particle size (PS), polydispersity index (PdI), zeta potential (ZP) and % entrapment efficiency (%EE) of 286.8 ± 1.3 nm, 0.413 ± 0.017, -48.6 ± 0.89 mV and 88.31 ± 2.04%, respectively. The optimized formulation observed by transmission and scanning electron microscopes showed a spherical shape. Differential scanning calorimetry study revealed the absence of chemical interaction between the drug and lipids. In vitro cellular uptake study using Caco-2 cell line showed a higher LPV uptake from LPV-NLC-7-Tres formulation compared to the free LPV-suspension. The 6-month stability study showed a minimum rise of ~40 nm in PS, while no significant changes in PdI, ZP and drug content of the LPV-NLC-7-Tres formulation stored at 5 °C ± 3 °C. The bioavailability of LPV following oral administration of LPV-NLC-7-Tres in male Wistar rats was found 6.98-fold higher than the LPV-suspension. In conclusion, the nanostructure lipid carriers are potential carriers for improving the oral bioavailability of lopinavir.
The demand for carbon dioxide (CO2) gas detection is increasing nowadays. However, its fast detection at room temperature (RT) is a major challenge. Graphene is found to be the most promising sensing material for RT detection, owing to its high surface area and electrical conductivity. In this work, we report a highly edge functionalized chemically synthesized reduced graphene oxide (rGO) thin films to achieve fast sensing response for CO2 gas at room temperature. The high amount of edge functional groups is prominent for the sorption of CO2 molecules. Initially, rGO is synthesized by reduction of GO using ascorbic acid (AA) as a reducing agent. Three different concentrations of rGO are prepared using three AA concentrations (25, 50, and 100 mg) to optimize the material properties such as functional groups and conductivity. Thin films of three different AA reduced rGO suspensions (AArGO25, AArGO50, AArGO100) are developed and later analyzed using standard FTIR, XRD, Raman, XPS, TEM, SEM, and four-point probe measurement techniques. We find that the highest edge functionality is achieved by the AArGO25 sample with a conductivity of ~1389 S/cm. The functionalized AArGO25 gas sensor shows recordable high sensing properties (response and recovery time) with good repeatability for CO2 at room temperature at 500 ppm and 50 ppm. Short response and recovery time of ~26 s and ~10 s, respectively, are achieved for 500 ppm CO2 gas with the sensitivity of ~50 Hz/µg. We believe that a highly functionalized AArGO CO2 gas sensor could be applicable for enhanced oil recovery, industrial and domestic safety applications.
Grain size spectrum and textural parameters for the fluvial sediment bed in seven tropical rivers of Kelantan, Malaysia are presented in this article. The samples were collected from six tributaries to the main Sungai Kelantan spanning approximately 248 km stretch of water streams. Sand or gravel dominated river was identified for each river using the sediment composition analysis. Textural pattern shows complicated profiles of mean size and no consistent decreasing grain size and gradation parameter were observed towards the downstream flow. Most of the samples fall under the category of either very poorly sorted or poorly sorted and has very platykurtic kurtosis distributions. CM diagram (C=one percentile in microns and M = median grain size in microns) suggested that the deposition of fine-grained sediment for samples with median grain size d50 <1 mm are either by rolling, rolling and saltation or saltation and suspension.
This study aimed to improve the colloidal stability of yttria-stabilized tetragonal zirconia polycrystalline (Y-TZP)
suspension through colloidal processing to obtain highly translucent Y-TZP. Agglomeration is often the main complication
in the processing of nanosized Y-TZP as it deteriorates mechanical and optical properties. Thus, colloidal processing
is necessary to mitigate the agglomeration in Y-TZP. The colloidal stability of Y-TZP suspension plays a key role for the
success of colloidal processing. In this study, colloidal processing was conducted at several stages, namely, dispersant
addition, pH adjustment and sedimentation. Changes in particle size and zeta potential at various stages were recorded.
The suspensions were then slip-casted to form green bodies. Green bodies were sintered and characterized for density
and translucency. The results showed that dispersant addition followed by pH adjustment effectively dispersed soft
agglomerates by introducing electrosteric stabilization, whereas sedimentation successfully segregated hard agglomerates
and contributed excellent colloidal stability. With high colloidal stability, the translucency of Y-TZP was improved by
approximately 30%. This study demonstrated different colloidal processing stages and proved that high colloidal stability
and fine particle size are vital to produce highly translucent Y-TZP.