23 research outputs found

    Comparing the Reaction Rates of Plasmonic (Gold) and Non-Plasmonic (Palladium) Metal Particles in Photocatalytic Hydrogen Production

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    Both Pd and Au metal particles are used in photocatalytic hydrogen generation. Yet while both act as electron sink only gold is poised to respond to visible light due to its plasmonic response. In order to quantitatively gauge their relative contribution into the reaction, the photocatalytic H2 production, from Au/TiO2 and Pd/TiO2 catalysts was studied under UV and UV–Vis light. While under UV light excitation, a weak dependence on the work function of the metal is observed, under UV–Vis light, Au is found to be twice more active than Pd. Under identical UV–Vis light irradiation, the turn over frequency calculated from XPS at.% is found to be 2.8 and 1.8 s−1 for Au and Pd, respectively. The effect is far more pronounced when the rates are normalized to the number of particles of each metal. Both the semiconductor TiO2 (UV light) and the plasmonic metal (visible light) need to be excited for the enhancement to occur; visible light alone causes a negligible reaction rate. Photocurrent measurements further confirmed the difference in the photocatalytic activity under UV and UV–Vis light excitation. Moreover, because of the presence of Au particles responding to visible light the reaction rate is enhanced due to “light penetration depth” effect

    EGZOENCIMI U HRANI ZA RIBE S POSEBNIM OSVRTOM NA FITAZU: PREGLED

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    The global aquaculture industry has come under increasing pressure to optimize production efficiency while reducing environmental loadings. These new demands, which have been accompanied in certain countries by legislation, have stimulated the development of elite low output dietary formulations. Several feed manufacturers have developed diets with modified energy: protein ratios, which reduce environmental phosphorus loadings with minimum impact upon fish growth. However, problems relating to end product quality have materialized following application of these high lipid diets and it is clear that alternative strategies must be developed. In particular, there remains an urgent need to replace the expensive fishmeal component of aquafeeds. One approach might be to supplement diets with exogenous enzymes (exoenzymes) that enhance the value and utility of alternative, low grade proteins while reducing ecological impacts. This paper briefly reviews the literature relating to experimental exoenzyme aquafeeds, with specific reference to phytase.Kompletna industrija akvakulture nalazi se pod povećanim pritiskom glede optimalizacije efikasne proizvodnje, dok se u isto vrijeme smanjuju mogućnosti iskorištavanja akvatorija. Ovi, novi zahtjevi koji su u nekim zemljama povezani s legislativom, potaknuli su razvoj niskih iskorištenosti hranidbenih formulacija. Nekoliko proizvođaća razvilo je hrane s modificiranom energijom: količina bjelančevina koja smanjuje nakupljanje P a okolišu s minimalnim utjecajem na rast riba. No, problemi koji se odnose na kvalitetu gotovoga proizvoda materijalirizirani su uporabom hrana s visokim postotkom lipida i jasno je da mora biti razvijena alternativna strategija, napose stoga što ostaje urgentna potreba za zamjenu skupog ribljeg brašna kao komponente u hrani za ribe. Jedna od mogućnosti mogla bi biti dodatak egzogenih enzima (egzoenzima) koji povećavaju vrijednost i iskorištenost nisko vrijednih bjelančevina. U ovom je radu dan kratak prikaz literaturnih podataka koji se odnose na eksperimentalne hrane s egzoenzimima, s posebnim osvrtom na fitazu

    EGZOENCIMI U HRANI ZA RIBE S POSEBNIM OSVRTOM NA FITAZU: PREGLED

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    The global aquaculture industry has come under increasing pressure to optimize production efficiency while reducing environmental loadings. These new demands, which have been accompanied in certain countries by legislation, have stimulated the development of elite low output dietary formulations. Several feed manufacturers have developed diets with modified energy: protein ratios, which reduce environmental phosphorus loadings with minimum impact upon fish growth. However, problems relating to end product quality have materialized following application of these high lipid diets and it is clear that alternative strategies must be developed. In particular, there remains an urgent need to replace the expensive fishmeal component of aquafeeds. One approach might be to supplement diets with exogenous enzymes (exoenzymes) that enhance the value and utility of alternative, low grade proteins while reducing ecological impacts. This paper briefly reviews the literature relating to experimental exoenzyme aquafeeds, with specific reference to phytase.Kompletna industrija akvakulture nalazi se pod povećanim pritiskom glede optimalizacije efikasne proizvodnje, dok se u isto vrijeme smanjuju mogućnosti iskorištavanja akvatorija. Ovi, novi zahtjevi koji su u nekim zemljama povezani s legislativom, potaknuli su razvoj niskih iskorištenosti hranidbenih formulacija. Nekoliko proizvođaća razvilo je hrane s modificiranom energijom: količina bjelančevina koja smanjuje nakupljanje P a okolišu s minimalnim utjecajem na rast riba. No, problemi koji se odnose na kvalitetu gotovoga proizvoda materijalirizirani su uporabom hrana s visokim postotkom lipida i jasno je da mora biti razvijena alternativna strategija, napose stoga što ostaje urgentna potreba za zamjenu skupog ribljeg brašna kao komponente u hrani za ribe. Jedna od mogućnosti mogla bi biti dodatak egzogenih enzima (egzoenzima) koji povećavaju vrijednost i iskorištenost nisko vrijednih bjelančevina. U ovom je radu dan kratak prikaz literaturnih podataka koji se odnose na eksperimentalne hrane s egzoenzimima, s posebnim osvrtom na fitazu

    PROBAVNI SUSTAV KOŠTUNJAČA PERSORBIRA MIKROČESTICE

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    The ability of the teleost gut to absorb microparticulate material was examined following rectal intubation (3.5 g kg -1 ) of commercial grade cornstarch (≈21 mm diameter), or potato starch (≈43 mm diameter). Tissue samples were taken from the mid - and hind-gut of control and treated fish 18 h postintubation. Collected samples were processed using standard plastic and staining protocols and resultant photomicrographs examined by computer-assisted image analysis. Cornstarch particles (8-14 mm), were observed to pass from gut lumen to the lamina propria via a paracellular or persorptive route only. No evidence for the like passage of potato starch was found.Mogućnost probavnog sustava koštunjavičastih vrsta riba da apsorbiraju sitne čestice pojedinih tvari bila je istraživana s pomoću rektalne intubacije (3, 5 g kg -1 ) komercijalnoga škroba kukuruza (promjera ≈21 mm) i škroba krumpira (promjera ≈ 43 mm). Uzorci tkiva uzeti su iz srednjeg i stražnjeg dijela crijeva kontrolne i tretirane skupine riba, i to 18 sati nakon intubacije. Sakupljeni su uzorci spremljeni u standardne plastike i obojeni prema protokolu, te fotomikrografski snimljeni na računalu. Čestice škroba kukuruza (8-14 mm) zapažene su da iz lumena crijeva prolaze u laminu propriju samo paracelularnim ili persorptivnim putem. No, nije zapažen prolazak čestica škroba krumpira

    PROBAVNI SUSTAV KOŠTUNJAČA PERSORBIRA MIKROČESTICE

    Get PDF
    The ability of the teleost gut to absorb microparticulate material was examined following rectal intubation (3.5 g kg -1 ) of commercial grade cornstarch (≈21 mm diameter), or potato starch (≈43 mm diameter). Tissue samples were taken from the mid - and hind-gut of control and treated fish 18 h postintubation. Collected samples were processed using standard plastic and staining protocols and resultant photomicrographs examined by computer-assisted image analysis. Cornstarch particles (8-14 mm), were observed to pass from gut lumen to the lamina propria via a paracellular or persorptive route only. No evidence for the like passage of potato starch was found.Mogućnost probavnog sustava koštunjavičastih vrsta riba da apsorbiraju sitne čestice pojedinih tvari bila je istraživana s pomoću rektalne intubacije (3, 5 g kg -1 ) komercijalnoga škroba kukuruza (promjera ≈21 mm) i škroba krumpira (promjera ≈ 43 mm). Uzorci tkiva uzeti su iz srednjeg i stražnjeg dijela crijeva kontrolne i tretirane skupine riba, i to 18 sati nakon intubacije. Sakupljeni su uzorci spremljeni u standardne plastike i obojeni prema protokolu, te fotomikrografski snimljeni na računalu. Čestice škroba kukuruza (8-14 mm) zapažene su da iz lumena crijeva prolaze u laminu propriju samo paracelularnim ili persorptivnim putem. No, nije zapažen prolazak čestica škroba krumpira

    The Influence of Employee-Centered and Organizational Communication on Employee Resistance to Change: A Study at Rabigh Refinery in Saudi Arabia

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    The objective of the study was to determine the influence of employee–centered and organizational communication on employee resistance to change. This study was held at the Rabigh Refinery in Saudi Arabia. Furthermore, this study also tried to determine if the relationship between the variables is moderated by personality. The study was conducted amongst the employees of Rabigh Refinery industrial organizations at Rabigh City in Saudi Arabia (N=302). Considering the importance of understanding change processes and factors that contribute to successful change nowadays, it is valuable to increase insight into the factors that determine resistance to change. Moreover, since resistance to change is the most frequently cited implementation problem encountered by management when introducing change, especially understanding the factors that determine employee resistance to change is valuable, and for the purpose of data analysis and hypotheses testing, several statistical methods, such as hierarchical multiple regressions analysis and hierarchical regression analysis was utilized to understand the dimensionality of the variables. The findings resulted in acceptance of the study hypotheses formulated. Factors like employee involvement, employee benefits, career development and organizational communication significantly influenced the resistance to change. In addition, the relationship between variables and personality was tested. The findings also showed that two of the personality traits (extraversion and conscientiousness) moderated the relationships between employee involvement, benefits, career development, communication and resistance to change. Based on the research findings, theoretical implications are discussed. Limitations and suggestions for future research are also highlighted. Hence, with limited literature on the area of resistance to change in industrial organizations, the findings have, to some extent, contributed to the understanding of the concept and further enhanced the knowledge in this area, especially in Saudi Arabia and other Arab countries

    Evaluating the quality and storage stability of fish burgers during frozen storage

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    In an attempt to initiate seafood biotechnology in the Sultanate of Oman, Middle East, using underutilized fish, fish burgers from two different formulas were developed and the quality and storage stability were evaluated during storage at -20°C for 3 months. Quality and storage stability were evaluated through total aerobic and coliform bacterial count, peroxide value, protein solubility, and color. Total aerobic bacteria were reduced significantly (P < 0.05) by 84% and 97% of the initial load in formulas 1 and 2, respectively, whereas coliforms were completely destroyed in both formulas at the end of storage. Peroxide value increased (P < 0.05) but did not reach detectable levels of rancidity. Salt-soluble protein content decreased remarkably during the storage period. The L value showed good stability during storage, keeping products bright for 3 months. Fish burgers from both formulas were acceptable for 3 months at -20°C. Storage stability was rationalized by the effectiveness of freezing, and antimicrobial and antioxidant properties of food additives. In an attempt to initiate seafood biotechnology in the Sultanate of Oman, Middle East, using underutilized fish, fish burgers from two different formulas were developed and the quality and storage stability were evaluated during storage at -20°C for 3 months. Quality and storage stability were evaluated through total aerobic and coliform bacterial count, peroxide value, protein solubility, and color. Total aerobic bacteria were reduced significantly (P < 0.05) by 84% and 97% of the initial load in formulas 1 and 2, respectively, whereas coliforms were completely destroyed in both formulas at the end of storage. Peroxide value increased (P < 0.05) but did not reach detectable levels of rancidity. Salt-soluble protein content decreased remarkably during the storage period. The L value showed good stability during storage, keeping products bright for 3 months. Fish burgers from both formulas were acceptable for 3 months at -20°C. Storage stability was rationalized by the effectiveness of freezing, and antimicrobial and antioxidant properties of food additives

    Different Method Estimations of the Three Parameters of Exponentiated Gompertz Distribution

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    This article discusses the maximum likelihood, least squares, weighted least squares, and percentiles estimates of three parameters of an exponentiated Gompertz distribution based on complete sample. By using the mean square error through Monte Carlo simulation, this study compares the performances of estimates. Real data set is used as an example of the methods of estimations for the three parameters of exponentiated Gompertz distribution

    Organizational change resistance: A review of employees’ reactions in Rabigh Refinery in Saudi Arabia

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    Generally, organization experiences stress and difficulties in dealing with change. However, introducing and coping with change is inevitable in today’s global competition. Any organizational change may encounter many difficulties and challenges, especially when the change is actually executed. One of the challenges is due to employees’ resistance. Some of the resistance are logical and supported with rational reasons, but in some other cases the change is turndown with irrational justifications. This present paper provides review on employees’ reactions toward organizational changes. A special focus was made to highlight two types of reactions, which are: (1) passive and (2) active resistance. This paper also highlights prominent reasons why the employees resist and recommends steps to be taken to minimize negative effects while undertaking any organizational change process
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