36 research outputs found
INTENTION TO USE FINGERPRINT SYSTEM IN ELECTRONICS INDUSTRY
Purpose: The aim of this study is to assist the Malaysian electronics companies in reducing the non-value added practices and in return, will minimize the cost and improves productivity with the use of the fingerprint system.
Methodology: This study uses a quantitative research approach and data were sampled from 137 front-line employees using simple random sampling technique.
Result: The empirical findings of the study confirm that perceived usefulness and perceived ease of use significantly affect the intention to use the fingerprint system. However, there was not enough evidence that relative advantage has any effect on the intention to use the system.
Implications: The study results affirmed that business organizations, especially electronic companies should transform their use of conventional attendance system to fingerprint system in improving efficiencies and effectiveness within the human resource practices
Turnover intention among manufacturing industry employees in Malaysia: an analysis using structural equation modeling (SEM)
This research paper explores the turnover intention among manufacturing industry employees in
Malaysia. Four variables were studied: role overload, role ambiguity, role conflict, and work-family
conflict. The survey results collected from 153 employees from manufacturing companies in Malaysia.
The analysis been obtained via SEM-PLS. Total four hyphotheses were tested. Positive results obtained
for role overloaded towards turnover intention. Negative results obtained for role ambiguity, role
conflict, and work-family conflict. Based on the findings all the manufacturing recognize importance of
staff retention for superior value for an organization
Experiential quality among coffee lovers: an empirical study in the Malaysian coffee outlets industry
Experiential Quality has become extremely important for coffee outlets industry due to the highly
competitive environment. The main objective of this study is to analyze the quality of the coffee outlets
to win more customers in Malaysia. This study specifically design to investigate the existing literature
on experiential quality comprising Interaction quality, Physical environment quality, Outcome quality
and Affective quality. Researcher used a self-administrated questionnaire survey with a sample size of
200 respondents from various coffee outlets in Selangor, Malaysia (One of the state with high population
in Malaysia). The Findings shows that Interaction quality, Physical environment quality, and Outcome
quality have direct effect on experimental quality among coffee lovers. Affective quality shows an
negative effect on experiential quality. Coffee is one of the global product. Coffee sold at branded coffee
outlets are niche market product. Coffee outlets industry is a classified destination of consumers with
intrinsic value of coffee. Coffee outlets offer typical coffer qualities in attractive environment to
withhold coffee lovers. This special product is consumed by middle income and higher income social
class consumers. The findings further implied coffee outlets focused at managing coffee lovers’ service
quality expectation to create and enlarge greater coffee loyalist for sustainable competitive advantage
Mono- und multivalente Wechselwirkungen zwischen Thiol- und Amin-Liganden mit Edelmetallnanopartikeln
In this thesis, the interactions between mono- and multivalent thiol and amine
ligands and noble metal nanoparticles are investigated. The multivalent
interactions are characterized by the simultaneous binding of multivalent
ligands on one entity to multivalent receptors on another one. The binding
affinities of multivalent ligands are stronger than that of monovalent ones.
So far, multivalent interactions with nanoparticles are not fully explored.
Therefore, different physico-chemical techniques are used to investigate the
interactions between mono- and multivalent ligands with nanoparticles. The
results gathered in this work are divided into four parts. In first part, the
effect of the ligand’s multivalency and the nanoparticles size on the binding
kinetics of thiol ligands on gold nanoparticles is evaluated by exchanging
monovalently bound pyrene thiol ligands bound to gold nanoparticles against
flexible mono- and multivalent thiol ligands. For this, gold nanoparticles
with diameters of 2.2±0.4 nm, 3.2±0.7 nm, and 4.4±0.9 nm are used as
substrates. The pyrene thiol is used as a fluorescent probe as well as a
stabilizer of the gold nanoparticles before the ligand exchange reaction takes
place. The effects of the ligand’s multivalency and the particles size are
evaluated by comparing the rate constants of the ligand exchange reactions. To
evaluate these effects, the experimental data have been fitted by using
various models. The results from kinetics studies are well fitted by a bi-
exponential function as well as by a second order Langmuir diffusion models.
However, only a bi-exponential fit function can reasonably explain the
processes occurring with the ligand exchange process. Systematic
investigations reveal a significant enhancement of the reaction rates of di-
and trivalent ligands compared to the monovalent ones. This is attributed to a
distinct multivalency effect. In contrast, the exchange rates of the trivalent
ligands are similar or even lower than those of the divalent ones. This is
explained by steric hindrance of bulky trivalent ligands. In addition, it is
also observed that the rate constants increase with the particle size. The
results are used to derive structural information on the binding of the mono-
and multivalent ligands to the nanoparticles surface. Furthermore, it turns
out, that gold particles larger than 4 nm in diameter aggregate during the
ligand exchange reaction, likely because the non-bulky incoming alkyl thiol
ligands do not provide sufficient steric stabilization. In the second part of
this work, the binding of rigid aromatic thiols on gold nanoparticles of
2.2±0.4 nm, 3.2±0.7 nm, and 4.4±0.9 nm is investigated. The pyrene thiol bound
on gold nanoparticles is exchanged by 4-toluenethiol or 3,4-toluenedithiol.
During the exchange reaction, the particles aggregate immediately after the
addition of the aromatic rigid thiol ligands. This clearly shows that flexible
alkyl thiol ligands provide sufficient steric stabilization for the gold
nanoparticles than the rigid aromatic thiol ligands. In the third part, the
binding of mono- and multivalent alkyl thiol ligands on silver nanoparticles
with 4.6±2.0 nm diameter is studied, wherein the same alkyl thiol ligands
which are also used in the experiments on gold nanoparticles are used. Silver
particles stabilized by pyrene thiol ligands are synthesized and the thiol
ligands are exchanged by the mono- and multivalent alkyl thiol ligands. During
the exchange process partial precipitation of the particles occurs as a
consequence of severe aggregation. The results on the silver nanoparticles are
compared to those obtained from gold nanoparticles of a similar size (4.4±0.9
nm) during the exchange of pyrene thiol against mono- and multivalent alkyl
thiol ligands. The exchange rates of pyrene thiol with di- and trivalent
ligands are similar for silver and gold nanoparticles. In case of the
monovalent ligands, initially, the exchange rate on silver nanoparticles seems
to be faster than on gold nanoparticles. In last part of this work, the
influence of the presence of mono-, di-, and trivalent alkyl amine ligands on
the nucleation and growth of platinum and silver nanoparticles is
investigated. Here, for the first time mono- and multivalent amine ligands are
used to control the formation of platinum and silver nanoparticles using
platinum (II) acetylacetonate and silver (II) acetylacetonate as precursors,
respectively. Platinum and silver nanoparticles are prepared by one-step
processes at 200 °C and 120 °C, respectively, in order to investigate the
influence of the amine ligands on the formation of nanoparticles.
Additionally, procedures are applied, where the reaction temperature is
stepwise increased between 160 and 200 °C in the case of platinum and between
80 and 120 °C for silver. The multivalency effects of the ligands on the
formation of platinum particles are investigated by using TEM measurements.
The platinum particles prepared at 200 °C in the presence of monovalent
ligands are rather polydisperse and have a non-spherical shape, whereas the
di- and trivalent ligands cause the growth of monodisperse and spherical
particles. In contrast, platinum particles prepared by stepwise increasing the
temperature have a spherical shape independent on the ligand multivalency and
the reaction temperature. The influence of the ligand’s multivalency on the
formation, growth, and stability of silver particles is investigated by TEM
and UV-Vis measurements. The size distributions of the silver particles
prepared by a one-step process are wider than those of the particles prepared
by a stepwise process. This is because faster nucleation and growth processes
take place and as a consequence, nucleation and growth are not well separated
if the particles are prepared by a one-step process at high temperature
instead of a stepwise process at lower temperatures.In dieser Arbeit werden die Wechselwirkungen zwischen mono- und multivalenten
Thiol- und Amin-Liganden und Edelmetall-Nanopartikeln untersucht.
Charakteristisch für die multivalenten Wechselwirkungen ist die zeitgleiche
Bindung multivalenter Liganden einer Spezies an multivalente Rezeptoren einer
anderen Spezies. Dabei ist die Bindungsenergie der multivalenten Bindung
größer, als die Summe der einzelnen, monovalenten Bindungen. Die Untersuchung
des Multivalenzeffektes erfolgt mittels verschiedener physikalisch-chemischer
Techniken mit dem Ziel, das grundlegende Verständnis der Wechselwirkungen
zwischen multivalenten Liganden und Nanopartikeln zu verbessern. Die
Ergebnisse dieser Arbeiten sind in vier Teilen zusammengefasst. Im ersten Teil
werden der Einfluss der Multivalenz der Liganden sowie der Größe der
Nanopartikel auf die Bindungskinetik von Thiol-Liganden auf Goldnanopartikel
anhand des Austausches von monovalent gebundenen Pyren-Thiol-Liganden gegen
flexible mono- und multivalente Alkyl-Thiol-Liganden untersucht. Dazu werden
Gold-Nanopartikel mit einem Druchmesser von 2.2±0.4 nm, 3.2±0.7 nm und 4.4±0.9
nm als Substrat verwendet. Die Pyren-Thiol-Liganden dienen als fluoreszierende
Sonden und zur Stabilisierung der Goldnanopartikel vor dem Ligandenaustausch.
Die Auswirkungen der Multivalenz der Liganden und der Partikelgröße werden
durch den Vergleich der Geschwindigkeitskonstanten der Liganden-Austausch-
Reaktionen ermittelt. Um diese besser beurteilen zu können, wurden die
erhaltenen Ergebnisse mit verschiedenen Modellen angepasst. Es stellte sich
heraus, dass sich die Daten aus den Kinetik-Versuchen mit einer
biexponentiellen Funktion und einem Langmuir-Diffusions-Modell zweiter Ordnung
grundsätzlich annähnern lassen. Zur Anwendung kam jedoch ausschließlich das
biexponentielle Modell, da dieses die ablaufenden Prozesse korrekt beschreibt.
Systematische Untersuchungen zeigen eine deutliche Erhöhung der
Reaktionsgeschwindigkeit di- und trivalenter Liganden im Vergleich zu den
monovalenten Liganden. Dies ist auf einen deutlichen Multivalenzeffekt
zurückzuführen. Im Gegensatz dazu ist die Austauschgeschwindigkeit der
trivalenten Liganden ähnlich oder gar niedriger als die der divalenten
Liganden. Dies wird durch die sterische Hinderung der sterisch anspruchsvollen
trivalenten Liganden erklärt. Darüber hinaus wird beobachtet, dass die
Geschwindigkeitskonstanten mit zunehmender Teilchengröße steigen. Die
erhaltenen Resultate werden dazu genutzt, Informationen über die Struktur der
Bindung der mono- und multivalenten Liganden an die Nanopartikel-Oberfläche
abzuleiten. Darüber hinaus hat sich gezeigt, dass Gold-Partikel mit einem
Durchmesser von mehr als 4 nm während des Ligandenaustausches aggregieren.
Dies ist wahrscheinlich auf die unzureichende sterische Stabilisierung durch
die Alkyl-Thiol-Liganden zurückzuführen. Im zweiten Teil wird die Bindung von
starren, aromatischen Thiolen an Goldnanopartikel mit einem Durchmesser von
2.2±0.4 nm, 3.2±0.7 nm und 4.4±0.9 nm untersucht. Die an die Partikel
gebundenen Pyren-Thiol-Liganden werden gegen 4-Toluolthiol und
3,4-Toluoldithiol substituiert. Während des Ligandenaustausches aggregieren
die Teilchen unmittelbar nach der Zugabe der aromatischen Thiole. Dies ist
möglicherweis auf eine unzulängliche sterische Stabilisierung der Goldpartikel
durch die starren, aromatischen Thiol-Liganden zurückzuführen. Es wird
deutlich, dass die flexiblen Alkyl-Thiol-Liganden im Vergleich zu den starren,
aromatischen Thiolen eine stärkere Stabilisierung der Goldnanopartikel
gewährleisten. Im dritten Abschnitt wird die Bindung von mono- und
multivalenten Alkyl-Thiol-Liganden an Silber-Nanopartikel mit 4.6±2.0 nm
Durchmesser untersucht, wobei die gleichen Liganden, die auch in den Versuchen
mit den Gold-Nanopartikeln genutzt wurden, zum Einsatz kommen. Durch Pyren-
Thiol-Liganden stabilisierte Silberpartikel werden synthetisiert und
anschließend die Pyren-Liganden gegen mono- und multivalente Alkyl-Thiol-
Liganden substituiert. Im Zuge dieses Austauschprozesses fallen die Partikel
teilweise aus, was eine Folge ausgeprägter Aggregationsprozesse ist. Die
erhaltenen Ergebnisse zu Silber-Nanopartikeln werden mit den Ergebnissen zum
Ligandenaustausch von Pyren-Thiol-Liganden gegen mono- und multivalente Alkyl-
Thiol-Liganden an Gold-Nanopartikel gleicher Größe verglichen. Die
Austauschgeschwindigkeit von Pyren-Thiolen gegen di- und trivalente Liganden
liegen im Fall von Gold- wie Silber-Nanopartikeln in derselben Größenordnung.
Im Fall der monovalenten Liganden scheint die Austauschgeschwindigkeit der
Liganden, die an Silberpartikel gebunden sind, höher zu sein als für
Goldnanopartikel. Im letzten Teil dieser Arbeit wird der Einfluss von mono-,
di- und trivalenten Alkyl-Amin-Liganden auf die Nukleation und das Wachstum
von Platin- und Silber-Nanopartikel untersucht. Zum ersten Mal wurden mono-
und multivalente Amin-Liganden verwendet, um die Bildung der Platin- und
Silber-Nanopartikel aus den Vorstufen Platin(II)acetylacetonat bzw.
Silber(II)acetylacetonat zu steuern. Um den Einfluss der Amin-Liganden auf die
Partikelbildung zu untersuchen, werden Platin- und Silber-Nanopartikel zum
einen durch ein einstufiges Verfahren bei 200 °C für Platin beziehungsweise
120 °C für Silber dargestellt. Zum anderen erfolgt die Synthese der Partikel
durch ein Verfahren, bei dem die Reaktionstemperatur schrittweise zwischen 160
und 200 °C im Fall von Platin bzw. 80 und 120 °C im Fall von Silber erhöht
wird. Die Auswirkungen des Multivalenz-Effektes der Liganden auf die Bildung
von Platinpartikel wird vor allem durch TEM-Experimente untersucht. Die bei
200 °C in Gegenwart monovalenter Liganden dargestellten Platin-Nanopartikel
weisen eine nicht-sphärische Form auf, wohingegen die mittels di- und
trivalenten Liganden synthetisierten Partikel sphärisch sind. Im Gegensatz
dazu führt die Synthesemethode mit einem schrittweisen Anstieg der Temperatur
zu sphärischen Partikeln, unabhängig von der Wahl des Liganden. Der Einfluss
der Valenz der Liganden auf die Bildung, das Wachstum und die Stabilität der
Silber-Partikel wird mittels dem TEM- und UV-Vis-Messungen untersucht. Die
Größenverteilung der Silberpartikel aus dem einstufigen Syntheseprozess ist
breiter als die der Teilchen, die durch ein stufenweises Verfahren hergestellt
worden sind. Der Grund hierfür liegt in den schnelleren Nukleations- und
Wachstumsprozessen im Fall des einstufigen Prozesses bei hohen Temperaturen,
die keine deutliche Trennung von Nukleation und Wachstum zulassen
Polymer Nanoparticles: Synthesis and Applications
Polymer nanoparticles (PNPs) are generally formed by the spontaneous self-assembly of polymers that vary size from 1 to 1000 nm [...
Controlled Synthesis of Platinum and Silver Nanoparticles Using Multivalent Ligands
Here, the controlled formation of platinum nanoparticles (PtNPs) and silver nanoparticles (AgNPs) using amine-functionalized multivalent ligands are reported. The effects of reaction temperature and ligand multivalency on the growth kinetics, size, and shape of PtNPs and AgNPs were systematically studied by performing a stepwise and a one-step process. PtNPs and AgNPs were prepared in the presence of amine ligands using platinum (II) acetylacetonate and silver (I) acetylacetonate, respectively. The effects of ligands and temperature on the formation of PtNPs were studied using a transmission electron microscope (TEM). For the characterization of AgNPs, additionally, ultraviolet-visible (UV-Vis) absorption was employed. The TEM measurements revealed that PtNPs prepared at different temperatures (160–200 °C, in a stepwise process) are monodispersed and of spherical shape regardless of the ligand multivalency or reaction temperature. In the preparation of PtNPs by the one-step process, ligands affect the shape of the PtNPs, which can be explained by the affinity of the ligands. The TEM and UV-Vis absorption studies on the formation of AgNPs with mono-, di-, and trivalent ligands showed narrower size distributions, while increasing the temperature from 80 °C to 120 °C and with a trivalent ligand in a one-step process
Novel cyclic tetraselenides of mannose: synthesis and mechanistic studies
In this Letter, we disclose the synthesis of novel cyclic tetraselenides starting from mannose which are very unusual and rare and have been synthesised for the first time. The structures are confirmed by X-ray analysis. The reactivity of the reagent tetraethylammonium tetraselenotungstate, has been compared with the well-known selenium transfer reagents and . A tentative reaction mechanism has been proposed
Synthesis of Water-Dispersed Sulfobetaine Methacrylate–Iron Oxide Nanoparticle-Coated Graphene Composite by Free Radical Polymerization
Research on the synthesis of water-soluble polymers has accelerated in recent years, as they are employed in many bio-applications. Herein, the synthesis of poly[2-(methacryloyloxy)ethyl]dimethyl-(3-sulfopropyl)ammonium hydroxide (PSB) by free radical polymerization in a sonication bath is described. PSB and iron oxide nanoparticles (IONPs) were simultaneously stabilized on the graphene surface. Graphene surfaces with PSB (GPSB) and graphene surfaces with PSB and IONPs (GPSBI) were prepared. Since PSB is a water-soluble polymer, the hydrophobic nature of graphene surfaces converts to hydrophilic nature. Subsequently, the prepared graphene composites, GPSB and GPSBI, were well-dispersed in water. The preparation of GPSB and GPSBI was confirmed by X-ray diffraction, Raman spectroscopy, field emission scanning electron microscopy, transmission electron microscopy, X-ray photoelectron spectroscopy, and thermogravimetric analysis. The impacts of PSB and IONPs on the graphene surfaces were studied systematically
Amphiphilic Fluorinated Block Copolymer Synthesized by RAFT Polymerization for Graphene Dispersions
Despite the superior properties of graphene, the strong π–π interactions among pristine graphenes yielding massive aggregation impede industrial applications. For non-covalent functionalization of highly-ordered pyrolytic graphite (HOPG), poly(2,2,2-trifluoroethyl methacrylate)-block-poly(4-vinyl pyridine) (PTFEMA-b-PVP) block copolymers were prepared by reversible addition-fragmentation chain transfer (RAFT) polymerization and used as polymeric dispersants in liquid phase exfoliation assisted by ultrasonication. The HOPG graphene concentrations were found to be 0.260–0.385 mg/mL in methanolic graphene dispersions stabilized with 10 wt % (relative to HOPG) PTFEMA-b-PVP block copolymers after one week. Raman and atomic force microscopy (AFM) analyses revealed that HOPG could not be completely exfoliated during the sonication. However, on-line turbidity results confirmed that the dispersion stability of HOPG in the presence of the block copolymer lasted for one week and that longer PTFEMA and PVP blocks led to better graphene dispersibility. Force–distance (F–d) analyses of AFM showed that PVP block is a good graphene-philic block while PTFEMA is methanol-philic
Controlled Synthesis of Platinum and Silver Nanoparticles Using Multivalent Ligands
Here, the controlled formation of platinum nanoparticles (PtNPs) and silver nanoparticles (AgNPs) using amine-functionalized multivalent ligands are reported. The effects of reaction temperature and ligand multivalency on the growth kinetics, size, and shape of PtNPs and AgNPs were systematically studied by performing a stepwise and a one-step process. PtNPs and AgNPs were prepared in the presence of amine ligands using platinum (II) acetylacetonate and silver (I) acetylacetonate, respectively. The effects of ligands and temperature on the formation of PtNPs were studied using a transmission electron microscope (TEM). For the characterization of AgNPs, additionally, ultraviolet-visible (UV-Vis) absorption was employed. The TEM measurements revealed that PtNPs prepared at different temperatures (160–200 °C, in a stepwise process) are monodispersed and of spherical shape regardless of the ligand multivalency or reaction temperature. In the preparation of PtNPs by the one-step process, ligands affect the shape of the PtNPs, which can be explained by the affinity of the ligands. The TEM and UV-Vis absorption studies on the formation of AgNPs with mono-, di-, and trivalent ligands showed narrower size distributions, while increasing the temperature from 80 °C to 120 °C and with a trivalent ligand in a one-step process