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Publication
Journal: ACS Applied Materials & Interfaces
January/5/2016
Abstract
In this report, a novel nanocomposite of highly dispersed CeO2 on a TiO2 nanotube was designed and proposed as a peroxidase-like mimic. The best peroxidase-like activity was obtained for the CeO2/nanotube-TiO2 when the molar ratio of Ce/Ti was 0.1, which was much higher than that for CeO2/nanowire-TiO2, CeO2/nanorod-TiO2, or CeO2/nanoparticle-TiO2 with a similar molar ratio of Ce/Ti. Moreover, in comparison with other nanomaterial based peroxidase mimics, CeO2/nanotube-TiO2 nanocomposites exhibited higher affinity to H2O2 and 3,3',5,5'-tetramethylbenzidine (TMB). Kinetic analysis indicated that the catalytic behavior was in accordance with typical Michaelis-Menten kinetics. Ce(3+) sites were confirmed as the catalytic active sites for the catalytic reaction. The first interaction of surface CeO2 with H2O2 chemically changed the surface state of CeO2 by transforming Ce(3+) sites into surface peroxide species causing adsorbed TMB oxidation. Compared with CeO2/nanowire-TiO2, CeO2/nanorod-TiO2, and CeO2/nanoparticle-TiO2, the combination of TiO2 nanotube with CeO2 presented the highest concentration of Ce(3+) thus leading to the best peroxidase-like activity. On the basis of the high activity of CeO2/nanotube-TiO2, the reaction provides a simple method for colorimetric detection of H2O2 and glucose with the detection limits of 3.2 and 6.1 μM, respectively.
Publication
Journal: Harvard Business Review
June/2/2008
Abstract
Work fills most executives' lives to the brim, leaving insufficient time for their families, their communities, and themselves. But Wharton professor Friedman suggests that, rather than view the problem as a set of trade-offs, executives use their leadership talents to benefit all four domains at once. The idea is to design experiments--small, short-term adjustments to their daily routines--that incorporate and mutually benefit the various aspects of their lives. If an experiment works out, everyone wins--employer, employee, family, and community; if it doesn't, it simply becomes a low-cost learning opportunity. Over time, the combination of small gains and lessons learned can lead to larger-scale transformation. The "Total Leadership" process involves identifying what's important to you, identifying what's important to everyone in your life, using those insights to creatively explore possibilities for experiments, and then selecting and implementing a few at a time. Drawing on decades of experience, Friedman has distilled nine categories of experiments that offer a manageable, systematic approach to the daunting task of conceiving projects with four-way benefits. In one such experiment, an executive might raise money for a charity her company sponsors by running a marathon with her son, thus simultaneously gaining greater visibility at work, spending more time with her family, giving back to the community, and improving her health. To move toward the goal of becoming a CEO, another executive might join the board of a nonprofit agency in his neighborhood together with his wife. Friedman suspects that there are far more opportunities for simultaneous benefits than people realize. They are there for the taking. You just have to know how to look for them and then find the support and courage to pursue them.
Publication
Journal: Carcinogenesis
January/6/1984
Abstract
The roles of chloroethylene oxide (CEO) and chloroacetaldehyde (CAA) in carcinogenicity of vinyl chloride (VC) have been studied by comparing biological effects of VC exposure with those of 2,2'-dichlorodiethylether (bis(chloroethyl)ether, BCEE) as a metabolic precursor of CAA. Biological end-points investigated were covalent protein binding, nucleic acid (RNA and DNA) alkylation and the potency of the two chemicals to induce preneoplastic ATPase-deficient foci in rat liver. After exposure of rats to [1-14C]BCEE, BCEE derived radioactivity was bound to liver proteins. Analysis of hydrolysates of liver RNA and DNA gave no indication for the formation of either 7-N-(2-oxoethyl)guanine, 1,N6-ethenoadenine or 3,N4-ethenocytosine residues within the nucleic acids. After application of VC, BCEE or chloroethanol [CE), also a precursor of CAA) to young rats, only animals exposed to VC developed preneoplastic hepatocellular ATPase-deficient foci. From these investigations it is concluded, that CEO (which is not formed during metabolism of BCEE and CE), not CAA, is the ultimate carcinogenic principle in VC carcinogenicity.
Publication
Journal: ACS Nano
November/12/2012
Abstract
In this work, we explore the catalytic application of atomically monodisperse, thiolate-protected Au(25)(SR)(18) (where R = CH(2)CH(2)Ph) nanoclusters supported on oxides for CO oxidation. The solution phase nanoclusters were directly deposited onto various oxide supports (including TiO(2), CeO(2), and Fe(2)O(3)), and the as-prepared catalysts were evaluated for the CO oxidation reaction in a fixed bed reactor. The supports exhibited a strong effect, and the Au(25)(SR)(18)/CeO(2) catalyst was found to be much more active than the others. Interestingly, O(2) pretreatment of the catalyst at 150 °C for 1.5 h significantly enhanced the catalytic activity. Since this pretreatment temperature is well below the thiolate desorption temperature (~200 °C), the thiolate ligands should remain on the Au(25) cluster surface, indicating that the CO oxidation reaction is catalyzed by intact Au(25)(SR)(18)/CeO(2). We further found that increasing the O(2) pretreatment temperature to 250 °C (above the thiolate desorption temperature) did not lead to any further increase in activity at all reaction temperatures from room temperature to 100 °C. These results are in striking contrast with the common thought that surface thiolates must be removed-as is often done in the literature work-before the catalyst can exert high catalytic activity. The 150 °C O(2)-pretreated Au(25)(SR)(18)/CeO(2) catalyst offers ~94% CO conversion at 80 °C and ~100% conversion at 100 °C. The effect of water vapor on the catalytic performance is also investigated. Our results imply that the perimeter sites of the interface of Au(25)(SR)(18)/CeO(2) should be the active centers. The intact structure of the Au(25)(SR)(18) catalyst in the CO oxidation process allows one to gain mechanistic insight into the catalytic reaction.
Publication
Journal: Journal of the American Chemical Society
February/28/2010
Abstract
A novel inverse CeO(2)/CuO catalyst for preferential oxidation of CO in H(2)-rich stream (CO-PROX) has been developed on the basis of a hypothesis extracted from previous work of the group (JACS 2007, 129, 12064). Possible separation of the two competing oxidation reactions involved in the process (of CO and H(2), respectively) is the key to modulation of overall CO-PROX activity and is based on involvement of different sites as most active ones for each of the two reactions. Achievement of large size CuO particles and adequate CeO(2)-CuO interfacial configurations in the inverse catalyst apparently allows appreciable enhancement of the catalytic properties of this kind of system for CO-PROX, constituting an interesting alternative to classic direct configurations so far explored for this process. Reasons for such behavior are analyzed on the basis of operando-XRD, -XAFS, and -DRIFTS studies.
Publication
Journal: Scientific Reports
September/7/2019
Abstract
Non-alcoholic fatty liver disease (NAFLD) is the most common cause of chronic liver disease worldwide, ranging from steatosis to non-alcoholic steatohepatitis (NASH). Recently, cerium oxide nanoparticles (CeO2NPs) have emerged as a new antioxidant agent with hepatoprotective properties in experimental liver disease. The aim of the current investigation was to elucidate whether CeO2NPs display beneficial effects in an experimental model of NAFLD.Therefore, fifteen Wistar rats were subjected to a methionine and choline deficient diet (MCDD) for 6 weeks and intravenously treated with CeO2NP or vehicle during the weeks three and four of the diet. The effect of CeO2NPs on serum biochemistry, hepatic steatosis, inflammation, fatty acid content and expression of reactive oxygen species (ROS) and lipid metabolism related genes was assessed. MCDD fed rats showed increased inflammation, enhanced hepatic lipid accumulation of both saturated and unsaturated fatty acids (FAs) and overexpression of genes related to fatty liver and ROS metabolism. Treatment with CeO2NPs was able to reduce the size and content of hepatocyte lipid droplets, the hepatic concentration of triglyceride- and cholesterol ester-derived FAs and the expression of several genes involved in cytokine, adipokine and chemokine signaling pathways. These findings suggest that CeO2NPs could be of beneficial value in NAFLD.
Publication
Journal: Zygote
September/18/2005
Abstract
As an important biological messenger, nitric oxide (NO) exhibits a wide range of effects during physiological and pathophysiological processes, including mammalian oocyte meiotic maturation. The present study investigated whether NO derived from two nitric oxide synthase (NOS) isoforms, inducible NOS (iNOS) or endothelial NOS (eNOS), is involved in the meiotic maturation of porcine oocytes. Meanwhile, the cumulus cells' function in meiotic maturation and their interaction with oocyte development and degeneration were also investigated using cumulus-enclosed oocytes (CEOs) and denuded oocytes (DOs). Different inhibitors for NOS were supplemented to the medium. Cumulus expansion, cumulus cell DNA fragmentation and oocyte meiotic resumption were evaluated 48 h after incubation. Aminoguanidine (AG), a selective inhibitor for iNOS, suppressed cumulus expansion and inhibited CEOs to resume meiosis (p < 0.05), but did not inhibit cumulus cell DNA fragmentation. Both Nomega-nitro-L-arginine (L-NNA) and Nomega-nitro-L-arginine methyl ester (L-NAME), inhibitors for both iNOS and eNOS, delayed cumulus expansion, inhibited cumulus cell DNA fragmentation and inhibited CEOs to resume meiosis. Such effects were not seen in DOs. These results indicate that iNOS-derived NO is necessary for cumulus expansion and meiotic maturation by mediating the function of the surrounding cumulus cells, and eNOS-derived NO is also involved in porcine meiotic maturation.
Publication
Journal: Journal of Hazardous Materials
March/31/2014
Abstract
Arsenic contaminated natural water is commonly used as drinking water source in some districts of Asia. To meet the increasingly strict drinking water standards, exploration of efficient arsenic removal methods is highly desired. In this study, hierarchically porous CeO₂-ZrO₂ nanospheres were synthesized, and their suitability as arsenic sorbents was examined. The CeO₂-ZrO₂ hollow nanospheres showed an adsorption capacity of 27.1 and 9.2 mg g(-1) for As(V) and As(III), respectively, at an equilibrium arsenic concentration of 0.01 mg L(-1) (the standard for drinking water) under neutral conditions, indicating a high arsenic removal performance of the adsorbent at low arsenic concentrations. Such a great arsenic adsorption capacity was attributed to the high surface hydroxyl density and presence of hierarchically porous network in the hollow nanospheres. The analysis of Fourier transformed infrared spectra and X-ray photoelectron spectroscopy demonstrated that the adsorption of arsenic on the CeO₂-ZrO₂ nanospheres was completed through the formation of a surface complex by substituting hydroxyl with arsenic species. In addition, the CeO₂-ZrO₂ nanospheres were able to remove over 97% arsenic in real underground water with initial arsenic concentration of 0.376 mg L(-1) to meet the guideline limit of arsenic in drinking water regulated by the World Health Organization without any pre-treatment and/or pH adjustment.
Publication
Journal: Journal of Health Organization and Management
December/5/2012
Abstract
OBJECTIVE
In many countries leadership theories and leadership development programs in healthcare have been dominated by individualistic and heroic approaches that focus on developing the skills and competencies of health professionals. Alternative approaches have been proffered but mainly in the form of post-heroic and distributed forms of leadership. The notion of "hybridity" has emerged to challenge the assumptions of distributed leadership. The paper seeks to explore how the concept of hybridity can be used to re-theorize leadership in healthcare as it relates to clinician managers (or hybrid-professional managers).
METHODS
The theoretical developments are explored and empirical material is presented from research in Australian public hospitals to support the case for the existence of hybridized forms of leadership in healthcare. The paper discusses whether hybridity needs re-theorizing to adequately account for clinician leadership. It contributes to debates surrounding the role of clinician leadership in healthcare reform particularly in relation to those doctors who occupy management positions at the division or unit levels as distinct to CEOs. The study uses qualitative research, i.e. interactive interviews to present accounts of how healthcare professionals describe leadership. It undertakes both deductive and inductive theme analysis of the interview material.
RESULTS
There is support for hybridized configurations of leadership in interview materials of healthcare professionals but other aspects were also noted that cannot be explained by this approach alone.
CONCLUSIONS
The paper is the first to examine the concept of hybridity in the context of clinician leadership. Many approaches to leadership in healthcare fail to address the complexity of leadership within the ranks of clinician managers and thus are unable to deal adequately with the role of leadership in healthcare reform and change.
Authors
Publication
(16626437; CEO; 10.1111/j.1442-9071.2006.01178.x)
Journal: Clinical and Experimental Ophthalmology
June/11/2006
Abstract
Racemose haemangioma of the retina is a rare, usually unilateral developmental abnormality: an arteriovenous communication with variable alterations in capillary and arteriolar networks. Herein a case of a 57-year-old man with a vitreous and subretinal haemorrhage in the left eye is described.
Publication
Journal: Avian Diseases
March/2/2011
Abstract
Two types of live attenuated vaccines have been used worldwide for the control of infectious laryngotracheitis virus (ILTV): 1) chicken embryo origin (CEO) vaccines; and 2) tissue culture origin vaccines (TCO). However, the disease persists in spite of extensive use of vaccination, particularly in areas of intense broiler production. Among the factors that may influence the efficiency of ILTV live attenuated vaccines is a possible interference of Newcastle Disease virus (NDV) and infectious bronchitis virus (IBV) vaccines with the protection induced by ILTV vaccines. The protection induced by CEO and TCO vaccines was evaluated when administered at 14 days of age alone or in combination with the B1 type strain of NDV (B1) and/or the Arkansas (ARK) and Massachusetts (MASS) serotypes of IBV vaccines. Two weeks after vaccination (28 days of age), the chickens were challenged with a virulent ILTV field strain (63140 isolate, group V genotype). Protection was evaluated at 5 and 7 days postchallenge by scoring clinical signs and quantifying the challenge virus load in the trachea using real-time PCR (qPCR). In addition, the viral load of the vaccine viruses (ILTV, NDV, and IBV) was quantified 3 and 5 days postvaccination also using qPCR. The results of this study indicate that the NDV (B1) and IBV (ARK) vaccines and a multivalent vaccine constituted by NDV (B1) and IBV (ARK and MASS) did not interfere with the protection induced by the CEO ILTV vaccine. However, the NDV (BI) and the multivalent (B1/MASS/ARK) vaccines interfered with the protection induced by the TCO vaccine (P < 0.05). Either in combination or by themselves, the NDV and IBV vaccines decreased the tracheal replication of the TCO vaccine and the protection induced by this vaccine, since the ILTV-vaccinated and -challenged chickens displayed significantly more severe clinical signs and ILTV load (P < 0.05) than chickens vaccinated with the TCO vaccine alone. Although NDV and IBV challenges were not performed, the antibody responses elicited by NDV and/or the IBV vaccinations were significantly reduced (P < 0.05) when applied in combination with the CEO vaccine.
Publication
Journal: Microbial Pathogenesis
September/8/2019
Abstract
In this study, the antimicrobial effects of cumin essential oil (CEO) and its mechanism of action through scanning electron microscopy (SEM) against Escherichia coli and Listeria innocua were investigated. The SEM images were taken at 0, 12 and 24 h at the minimum inhibitory concentration (MIC). The chemical composition of CEO was identified through gas chromatography/mass spectrometry (GC-MS). The antimicrobial effects of CEO were evaluated by the methods of Kirby-Bauer, well diffusion agar, microdilution broth and minimum bactericidal/fungicidal concentration (MBC/MFC). Antioxidant activity was examined by the methods of β-carotene/linoleic acid inhibition and 2,2-diphenyl-1-picrylhydrazyl. Total phenol content (TPC) was measured by Folin-Ciocalteu method. The subsequent analysis of CEO through GC-MS revealed that cuminal (28.28%) was the major compound of CEO. CEO showed a high TPC of 89.45 ± 0.78 mg GAE/g. The free radical scavenging activity of CEO (based on IC50) was equal to 9.10 ± 0.63 μg mL-1. In addition, CEO showed a remarkably high inhibitory effect (63%) on β-carotene bleaching via neutralizing hydroperoxides, which are responsible for the oxidation of highly unsaturated β-carotene. The antimicrobial effect increased as a function of essential oil concentration. However, there were no inhibitory effects on E. coli at 5 mg mL-1. The electron micrographs demonstrated that CEO caused an increase in the permeabilization of the cells and disrupted the membrane integrity.
Publication
Journal: Nanoscale
October/26/2015
Abstract
Controllable surface properties of nanocerias are desired for various catalytic processes. There is a lack of efficient approaches to adjust the surface properties of ceria to date. Herein, a redox chemical etching method was developed to controllably engineer the surface properties of ceria nanorods. Ascorbic acid and hydrogen peroxide were used to perform the redox chemical etching process, resulting in a rough surface and/or pores on the surface of ceria nanorods. Increasing the etching cycles induced a steady increase of the specific surface area, oxygen vacancies and surface Ce(3+) fractions. As a result, the etched nanorods delivered enhanced catalytic activity for CO oxidation, compared to the non-etched ceria nanorods. Our method provides a novel and facile approach to continuously adjust the surface properties of ceria for practical applications.
Publication
Journal: Zygote
May/23/2001
Abstract
This study was carried out to compare the possible role of a secreted paracrine factor versus that of a gap-junction-transmitted signal in mediating meiotic induction in isolated mouse oocytes from PMSG-primed, immature mice. In the first set of experiments, oocyte-cumulus cell complexes (OCC) were pretreated for 3 h with 2 mM dbcAMP or FSH, washed, and the oocytes then cultured for 17-18 h in 40 microl drops containing either 300 microM dbcAMP or 4 mM hypoxanthine (HX). Each set of pretreated oocytes was cultured under three different conditions: (1) intact cumulus-cell-enclosed oocytes (CEO); (2) denuded oocytes (DO), cultured alone after removal of cumulus cells; and (3) co-cultured cumulus cells and oocytes (CC/DO), where the cumulus cells were removed in the same drop with a mouth-operated pipette and cultured alongside the oocytes. When pretreated with high dbcAMP or FSH, maturation was stimulated in CEO when cultured in either inhibitor (by 41.4-53.7%). Pretreatment failed to affect the maturation rate in DO. DO maturation was not altered appreciably by co-cultured cumulus cells when arrest was maintained with dbcAMP. However, an increase in maturation of 21-23% was observed in CC/DO in the HX-containing cultures that was not dependent on prior treatment with a meiosis-inducing stimulus. When DO were co-cultured with intact, FSH-treated OCC, there was no evidence of a positive factor secreted by the stimulated complexes, despite the fact that oocytes within the OCC were induced to resume maturation. In a second series of experiments the gap junction inhibitor, 18alpha-glycyrrhetinic acid (GA), was utilised. An initial experiment determined that GA dose-dependently blocked OCC metabolic coupling (0.2% coupling at 10 microM compared with 13.6% in controls). When HX-arrested CEO and DO were cultured for 17-18 h in medium containing increasing concentrations of GA, meiotic maturation was induced in CEO but not DO, suggesting that the cumulus cells provided a positive stimulus in the absence of functional gap junctional communication. No effect of GA was seen in dbcAMP-arrested oocytes. A kinetics experiment showed that when CEO were cultured in dbcAMP +/- FSH, meiotic induction was initiated after 3 h and germinal vesicle breakdown reached 60% by 6 h. When GA was added to the cultures at different times after the initiation of culture (0, 2, 3, 4 and 5 h), meiotic induction was immediately blocked. In addition, measurement of OCC coupling revealed that no reduction in coupling occurred during this induction period in the absence of GA. It is concluded that cumulus cells can secrete a positive factor, but that this is normally overridden by inhibitory influences transmitted through the gap junction pathway in intact complexes. Furthermore, upon exposure of complexes to a meiosis-inducing stimulus, a positive gap-junction-mediated signal now predominates to trigger germinal vesicle breakdown, and this signal is utilised throughout the induction period.
Authors
Publication
Journal: ACS Applied Materials & Interfaces
April/6/2015
Abstract
We report a room-temperature NH3 gas sensor with high response and great long-term stability, including CeO2 NPs conformally coated by cross-linked PANI hydrogel. Such core-shell nanocomposites were prepared by in situ polymerization with different weight ratios of CeO2 NPs and aniline. At room temperature, the nanohybrids showed enhanced response (6.5 to 50 ppm of NH3), which could be attributed to p-n junctions formed by the intimate contact between these two materials. Moreover, the stability was discussed in terms of phytic acid working as a gelator, which helped the PANI sheath accommodate itself and enhance the mechanical strength and chemical stability of the sensors by avoiding "swelling effect" in high relative humidity. The sensors maintained its sensing characteristic (response of ca. 6.5 to 50 ppm of NH3) in 15 days. Herein, the obtained results could help to accelerate the development of ammonia gas sensor.
Publication
Journal: Vaccine
December/23/2009
Abstract
Two different regions of the infected cell protein 4 (ICP4) gene of infectious laryngotracheitis virus (ILTV) were amplified and sequenced for characterization of field isolates and tissue culture-origin (TCO) and chicken embryo-origin (CEO) vaccine strains. Phylogenetic analysis of the two regions showed differences in nucleotide and amino acid sequences between field isolates and attenuated vaccines. The PCR-RFLP results were identical to those obtained by DNA sequencing and validated their use to differentiate ILTV strains. The approach using the sequencing of the two fragments of the ICP4 gene showed to be an efficient and practical procedure to differentiate between field isolates and vaccine strains of ILTV.
Publication
Journal: Journal of Colloid and Interface Science
May/24/2007
Abstract
Cerium oxide (CeO(2)) nanoparticles were prepared sonochemically, by using cerium nitrate and azodicarbonamide as starting materials, and ethylenediamine or tetraalkylammonium hydroxide as additives. The additives have a strong effect on the particle size and particle size distribution. CeO(2) nanoparticles with small particle size and narrow particle size distribution are obtained with the addition of additives; while highly agglomerated CeO(2) nanoparticles are obtained in the absence of additives. Monodispersed CeO(2) nanoparticles with a mean particle size of ca. 3.3 nm are obtained when tetramethylammonium hydroxide (TMAOH) is used as the additive and the molar ratio of cerium nitrate/azodicarbonamine/TMAOH is 1/1/1. Blue shifts of the absorption peak and the absorption edges of the products are observed in the UV-Vis absorption spectra as a result of the quantum size effect. The samples have been characterized using powder XRD, TEM, DLS, and absorption spectra.
Publication
Journal: Chemical Record
April/25/2019
Abstract
Among different metallic nanoparticles, sliver nanoparticles (Ag NPs) are one of the most essential and fascinating nanomaterials. Importantly, among the metal based nanoparticles, Ag NPs play a key role in various fields such as biomedicine, biosensors, catalysis, pharmaceuticals, nanoscience and nanotechnology, particularly in nanomedicine. A main concern about the chemical synthesis of Ag NPs is the production of hazardous chemicals and toxic wastes. To overcome this problem, many research studies have been carried out on the green synthesis of Ag NPs using green sources such as plant extracts, microorganisms and some biopolymers without formation of hazardous wastes. Among green sources, plants could be remarkably valuable to exploring the biosynthesis of Ag NPs. In this review, the green synthesis of Ag-based nanocatalysts such as Ag NPs, AgPd NPs, Au-Ag NPs, Ag/AgPd NPs, Ag/Cu NPs, Ag@AgCl NPs, Au-Ag@AgCl nanocomposite, Ag-Cr-AC nanocomposite and Ag NPs immobilized on various supports such as Natrolite zeolite, bone, ZnO, seashell, hazelnut shell, almond shell, SnO2 , perlite, ZrO2 , TiO2 , α-Al2 O3 , CeO2 , reduced graphene oxide (rGO), h-Fe2 O3 @SiO2 , and Fe3 O4 using numerous plant extracts as reducing and stabilizing agents in the absence of hazardous surfactant and capping agents has been focused. This work describes the state of the art and future challenges in the biosynthesis of Ag-based nanocatalysts. The fact about the application of living plants in metal nanoparticle (MNPs) industry is that it is a more economical and efficient biosynthesis biosynthetic procedure. In addition, the catalytic activities of the synthesized, Ag-based recyclable nanocatalysts using various plant extracts in several chemical reactions such as oxidation, reduction, coupling, cycloaddition, cyanation, epoxidation, hydration, degradation and hydrogenation reactions have bben extensively discussed.
Publication
Journal: Food Chemistry
August/21/2016
Abstract
The encapsulation by spray drying method of coriander essential oil (CEO) in various materials (chitosan, alginate, chitosan/alginate, chitosan/inulin) was studied. The viscoelastic properties of the oil-in-water (O/W) emulsions and the characteristics of CEO-loaded microcapsules like morphology, moisture, wettability, solubility, flowability properties, swelling and release mechanisms were investigated. The chitosan microcapsules had a brain-like structure while the alginate and chitosan/alginate microcapsules are spherical with a smooth surface. The Compressibility Index (CI=29.09-32.25%) and Hausner Ratio (HR=1.38-1.44) values showed that all the microcapsules prepared correspond to the "poor" flowability powders group. The chitosan microcapsules exhibited the maximum release rate at pH 2.5 while the alginate microcapsules exhibited the maximum release rate at pH 6.5. Kinetics and mechanism of CEO release were studied using various mathematical models such as, zero order, first order, Higuchi model and Peppas model. The diffusional exponent (n) values of Peppas equation explains a non Fickian transport mechanism and diffusion or diffusion-swelling controlled process.
Publication
Journal: Biology of Reproduction
July/7/1997
Abstract
This study was conducted to investigate 1) the capacity of in vitro-matured (IVM) marmoset oocytes to be fertilized and to support embryonic development in vitro and 2) oocyte meiotic maturation in relation to in vivo FSH administration, follicle size, and oocyte-cumulus cell status. Pairs of ovaries were collected on Day 4 of the follicular phase from adult females receiving either 1) human FSH (3 IU; n = 5) or 2) control (saline; n = 5) daily for 4 days. Antral follicles were excised from ovaries and separated into classes according to size: class 1 (660-840 microm), class 2 >> 840-1000 microm), class 3 >> 1000-1400 microm), and class 4 >> 1400 microm). A total of 823 partially naked and cumulus-enclosed oocytes (CEOs) were released from follicles and cultured in vitro. Cumulus cells remaining after 22 h were removed, metaphase II (MII) oocytes were inseminated with epididymal sperm, and resulting embryos were cultured until developmental arrest. Fluorescence microscopy was used to assess oocyte meiotic and embryo developmental progression. Oocyte germinal vesicle breakdown (GVB)- and MII-competencies increased significantly with follicular size (p < 0.01 and p < 0.0001, respectively), although they were independent of oocyte-cumulus cell associations. After 24 and 32 h in vitro, 69% and 93%, respectively, of CEOs with MII competence had completed meiotic maturation, and the rate of nuclear maturation increased progressively with follicle size (p < 0.01) and with the association of cumulus cells (p < 0.01). In vivo FSH priming slightly improved oocyte GVB- and MII-competencies (p < 0.01 and p < 0.05, respectively) and decreased the time required to achieve MII (p < 0.01). IVM oocytes from all follicle sizes fertilized (78-92%) in vitro, with 27% developing to morula- and 4% to blastocyst-stage embryos. This study demonstrates for the first time that IVM New World primate oocytes are able to support advanced preimplantation embryonic development in vitro. Oocyte meiotic competence and the time course of nuclear maturation are profoundly influenced by their follicular origin, and marginally by FSH treatment.
Publication
Journal: Sensors
August/12/2017
Abstract
We investigated selective detection of the target volatile organic compounds (VOCs) nonanal, n-decane, and acetoin for lung cancer-related VOCs, and acetone and methyl i-butyl ketone for diabetes-related VOCs, in humid air with simulated VOC contamination (total concentration: 300 μg/m³). We used six "grain boundary-response type" sensors, including four commercially available sensors (TGS 2600, 2610, 2610, and 2620) and two Pt, Pd, and Au-loaded SnO₂ sensors (Pt, Pd, Au/SnO₂), and two "bulk-response type" sensors, including Zr-doped CeO₂ (CeZr10), i.e., eight sensors in total. We then analyzed their sensor signals using principal component analysis (PCA). Although the six "grain boundary-response type" sensors were found to be insufficient for selective detection of the target gases in humid air, the addition of two "bulk-response type" sensors improved the selectivity, even with simulated VOC contamination. To further improve the discrimination, we selected appropriate sensors from the eight sensors based on the PCA results. The selectivity to each target gas was maintained and was not affected by contamination.
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Publication
Journal: Meat Science
July/8/2019
Abstract
The effect of coriander essential oil (CEO) at concentrations of 0.075-0.150 μL/g on pH, color, lipid oxidation (TBARS), residual nitrite concentration and microbial growth of cooked pork sausages produced with different levels of sodium nitrite (0, 50 and 100 mg/kg) was investigated. Artificial neural networks modeling and the multi-response optimization were used to determine the optimal combinations of process parameters and storage time. Reduced concentration of sodium nitrite (60 mg/kg) in combination with 0.12 μL/g of CEO resulted in satisfying redness (a* approx. 11.1) and improved oxidative (TBARS approx. 0.12 mg MDA/kg) and microbial stability (total plate count - TPC approx. 2.50 Log CFU/g) of cooked pork sausages during refrigerated storage. Therefore, the results of this paper revealed significant antioxidative and antimicrobial activity of CEO, and consequently its high potential of utilization in processing of cooked pork sausages with enhanced quality and shelf-life.
Publication
Journal: International Journal of Biological Macromolecules
November/19/2015
Abstract
Active biodegradable films from chitosan containing 10% to 30% w/w of citronella essential oil (CEO) and cedarwood oil (CWO) were developed by casting and solvent-evaporation method, and their physical, mechanical and thermal properties were investigated. Possible interactions between the chitosan chains and the essential oils were confirmed using Fourier-transform infrared spectroscopy (FTIR). Various amounts of CEO or CWO had significant effects on the films' mechanical properties, with the exception of 10% of CEO, which did not significantly affect the tensile strength of the films. The incorporation of the two tested oils provoked a remarkable reduction in the water-vapor permeability properties, with a decrease of about 63% when 30% CEO was added in chitosan films. Thermogravimetric analysis showed that degradation temperatures of the films containing CEO and CWO improved only slightly in comparison to control films without essential oils. FTIR spectra analysis provided some insights on the possible interactions between chitosan and the two essential oils used. This study suggests that active films can be developed by including CEO and CWO in a chitosan matrix. Such films can provide new formulation options for packaging industries in developing active packaging with potential food-technology applications.
Publication
Journal: Nanomaterials
March/12/2019
Abstract
The main objective of this work is the catalyst optimization of Fe₂O₃-, Co₃O₄-, NiO- and/or PdO- (transition element oxides-TEO) functionalized CeO₂ nanoparticles to maximize the conversion of asphaltenes under isothermal conditions at low temperatures (<250 °C) during steam injection processes. Adsorption isotherms and the subsequent steam decomposition process of asphaltenes for evaluating the catalysis were performed through batch adsorption experiments and thermogravimetric analyses coupled to Fourier-transform infrared spectroscopy (FTIR), respectively. The adsorption isotherms and the catalytic behavior were described by the solid-liquid equilibrium (SLE) model and isothermal model, respectively. Initially, three pairs of metal oxide combinations at a mass fraction of 1% of loading of CeNi1Pd1, CeCo1Pd1, and CeFe1Pd1 nanoparticles were evaluated based on the adsorption and catalytic activity, showing better results for the CeNi1Pd1 due to the Lewis acidity changes. Posteriorly, a simplex-centroid mixture design of experiments (SCMD) of three components was employed to optimize the metal oxides concentration (Ni and Pd) onto the CeO₂ surface by varying the oxides concentration for mass fractions from 0.0% to 2.0% to maximize the asphaltene conversion at low temperatures. Results showed that by incorporating mono-elemental and bi-elemental oxides onto CeO₂ nanoparticles, both adsorption and isothermal conversion of asphaltenes decrease in the order CeNi1Pd1 > CePd2 > CeNi0.66Pd0.66 > CeNi2 > CePd1 > CeNi1 > CeO₂. It is worth mentioning that bi-elemental nanoparticles reduced the gasification temperature of asphaltenes in a larger degree than mono-elemental nanoparticles at a fixed amount of adsorbed asphaltenes of 0.02 mg·m-2, confirming the synergistic effects between Pd and Fe, Co, and Ni. Further, optimized nanoparticles (CeNi0.89Pd1.1) have the best performance by obtaining 100% asphaltenes conversion in less than 90 min at 220 °C while reducing 80% the activation energy.
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