13 research outputs found
Synthesis and luminescent properties of aluminium oxide-titanium dioxide nanocomposites doped with different rare-earths ions
No full textAlumina-titania (Al2O3-TiO2) is one of the most useful nano-composites to host up-conversion rare-earth (UCRE) ions to prepare light emitting nano-materials or nano-phosphors. These nano-composites have received a special attention because of their excellent thermal, chemical and mechanical stability. Alumina (Al2O3) is a ceramic material with high level of strength, toughness and tribological properties. Titania (TiO2) is a wide bandgap semiconductor material that is used in different application including photocatalytic activities, solar cells, hydrogen storage and sensors.
The singly doped α- Al2O3:Yb3+ phosphor powder was successfully synthesized by solution combustion method. The structure of the phosphor powders was characterized with powder X-ray diffractometer (XRD). The XRD patterns confirmed that the phosphors crystallized in the hexagonal phases of α-Al2O3 with space group R3c and the average crystallite size was 29 nm estimated from Debye-Scherrer equation. The Fourier transform infrared (FTIR) measurements confirmed the characteristic bonds of Al-O from α-Al2O3. The particle morphology and elemental composition of the phosphors were characterized by field emission scanning electron microscope (FE-SEM) coupled with an energy dispersive x-ray spectroscopy (EDS). The phosphor powders were excited in ultraviolet (UV) region with excitation wavelength of 325 nm and the corresponding near infrared (NIR) emission was observed at 975 nm. The NIR emission was assigned to 2F5/2→2F7/2 transition of Yb3+. The bluish green emission with maxima at ~ 480 nm was observed as a result of cooperative luminescence of Yb3+ when the powders were excited in the NIR with excitation wavelength of 980 nm.
The TiO2:Er3+ nano-phosphor powder were successfully synthesized by sol-gel method at room temperature XRD confirmed that nano-phosphor has crystallized in the tetragonal phases of anatase and rutile with space groups of (see PDF full text) and (see PDF full text) , respectively. An average crystallite size of the undoped TiO2 was 26 nm. The FE-SEM confirmed nano-rods particle morphology with diameter and length of 78 ± 36 nm and 1.51 ± 0.30 μm, respectively. The FTIR revealed the characteristic bonds of Ti-O due to the presence of TiO6 in titania. The nano-phosphor powders were excited in the NIR region with excitation wavelength of 980 nm and the corresponding visible emissions were observed at 527, 564 and 665 nm. The green emission with maxima at 527 and 564 nm were assigned to (2H11/2, 4S3/2)→4I15/2 while red emission at 665 nm was assigned to 4F9/2→4I15/2 transition of Er3+ ion. The excited state absorption (ESA) mechanism of up-conversion (UC) process was discussed extensively.
The nano-composites of Al2O3-TiO2:Yb3+,Er3+ and Al2O3-TiO2:Yb3+,Tm3+ phosphor powders were successfully synthesized by sol-gel method. XRD patterns confirmed the mixed oxides of titania (TiO2) rutile phase and an early crystallization of alumina (α-Al2O3) phase. The XRD patterns were consistent with JCPDS card no. 46-1212 and 21-1272 for α-Al2O3 and TiO2 rutile phases, respectively. An average crystallite size of ~ 36 nm was estimated from Debye-Scherrer equation. FE-SEM confirmed nano-rods morphology self-assembled with spherical particles. In Yb3+-Er3+ codoped nano-composites; the powders were excited in the NIR region with excitation wavelength of 980 nm and corresponding visible emissions were observed at 523, 548 and 658 nm. The green emission with maxima at 523 and 548 nm were assigned to (2H11/2, 4S3/2)→4I15/2 while red emission at 658 nm was assigned to 4F9/2→4I15/2 transition of Er3+ ion. In Yb3+-Tm3+ codoped nano-composites; the powders were excited in NIR region with excitation wavelength of 980 nm and corresponding visible to NIR emissions were observed at 480, 650, 693 and 800 nm. The blue emission with maxima at 480 nm was assigned to 1G4→3H6, red emission with maxima at 650 and 693 nm were assigned to 1G4→3F4 and 3F3→3H6 and NIR emission with maxima at 800 nm was attributed to 3H4→3H6 transitions of Tm3+ ion. The other optical properties were investigated with the characterization techniques such as FTIR and UV-vis.National Nanoscience Postgraduate Teaching and Training Platform (NNPTTP)University of the Free Stat
Association between carotid intima-media thickness and patient outcomes in coronary artery disease in central South Africa
No full textThesis (Master: Health Sciences: Clinical Technology)--Central University of TechnologyObjectives Atherosclerosis is responsible for significant cardiovascular morbidity and mortality. Carotid intima medial thickness (CIMT) is a useful non-invasive tool to detect atherosclerosis to diagnose cardiovascular disease. The aim of the study was to assess the correlation between pre-operative CIMT measurements and intra- and post-operative surgical outcomes in acute coronary syndrome (ACS) patients undergoing coronary artery bypass graft (CABG) surgery. Methods This retrospective analytical cohort included 89 patients diagnosed with ACS who received CABG surgery. Patients were divided into two cohorts: group 1 (normal CIMT <0.07cm) and Group 2 (abnormal CIMT ≥0.07cm). B-mode ultrasound was used to measure the CIMT in all patients. Pre-, intra- and post-operative data and complications were recorded for each patient. Results The study included 77 (86.5%) males and 12 (13.5%) females. Pre-operative mean body mass index (BMI) was significantly higher (p=0.03) in group 2 than in group 1 (29.2 kg/m2 vs 26.6 kg/m2 ). Patients in group 2 had significantly more diabetes (p=0.008), hypertension (p=0.009) and an increased NT proBNP (p=0.02) than patients in group 1. The intra-operative and post-operative outcomes between groups were comparable, with no significant differences. Conclusion The study showed no correlation between abnormal CIMT and increased adverse intra- and postoperative patient outcomes. Therefore, based on the results of this study, CIMT should not be considered a tool to predict adverse events in patients undergoing CABG surgery
Fabrication of AgCu/TiO2 nanoparticle-based sensors for selective detection of xylene vapor
No full textThe design and fabrication of innovative nanostructured materials that could display improved sensitivity,
selectivity, and rapid response/recovery characteristics still present significant scientific challenges.
Herein we report the timely selective detection of xylene vapour in benzene, toluene, ethylbenzene
(BTE) and acetone vapours at low operating temperatures using an n-type AgCu/TiO2 nanoparticlebased sensor. Switching from p-type to n-type conductivity was observed at higher AgCu loadings. The
findings showed that sensor switching was not temperature- or gas-dependent. Among the AgCu
loaded on TiO2 nanoparticles, n-type 0.5% AgCu loaded on TiO2 displayed a remarkable response
(Rg/Ra E 33.2) toward xylene vapour at 150 1C. The sensor exhibited superior selectivity
National and institutional responses – reimagined operations – pandemic disruptions and academic continuity for a global university
No full textThe 2019/2020 academic year started well with no anticipation of what was in store for the second semester and how the year would end. New students were welcomed on campus and included international students and international faculty members. It was business as usual, a beautiful and colorful fall semester that transitioned into a cold winter season. Spring arrived after a long winter season and it was off to a good start as well until the pandemic hit.
This paper reflects on how an institution with multiple sites responded to the pandemic and what the impact of those disruptions were on the core activities of a university. As a university with the largest number of international students and a footprint on every continent, the university had to coordinate its activities around the world to complete the academic year and start another one. The university is the largest private employer in the city with over 50,000 students and more than 19,000 employees. The main focus of this reflection paper is the New York city campus where the author is based and key areas of this reflections include the impact of the pandemic on international students, teaching, research and funding related issues. Activities were normalized through central command instructions and guidance that were sometimes helpful and at other times overwhelming, but the work continued and the academic year was completed. The new academic year started with minor variations on the start dates. For example, the portal campuses at Abu Dhabi started on Sunday 6th September and New York city campus started on Wednesday 2nd September, whilst the Shanghai campus started on Monday the 14th. Reflections include personal impact and experiences within the academic setting.https://www.tandfonline.com/loi/cshe20hj2022Centre for the Advancement of Scholarshi
The Effect Of Filler Localization On The Properties Of Biopolymer Blends, Recent Advances: A Review
No full textArticleIn recent times, the field of biopolymer (BP) blends has been the focus of
intensive fundamental and applied researches. Such BP combinations possess
unique properties that are different from those of the individual components.
However, most polyester polymers are thermodynamically immiscible because
of their poor interactions. In the past, a third component, known as a welldefined
diblock or triblock copolymer, whose chemical structure is identical to
that of the main components, was usually used as a compatibilizer in order to
emulsify the interfacial phase, decreasing the interfacial tension and refining
the phase size. Currently, nanofillers are used to improve the phase morphologies
of immiscible BP blends. The main advantage of using nanofillers, when
compared to copolymers, is that the former can simultaneous act as nanoreinforcements
and compatibilizers. In this review, the addition of nanofillers
as the third component in the BP blend systems are reported in relation to
their morphologies, barrier properties, shape memory, thermal, and mechanical
properties. The effects of selectively localized nanofillers on the properties
of the BP blends are also explored, with the aim of establishing the relationships
between the localization of the fillers and the overall properties of the BP
blends. Furthermore, the effect of the processing techniques on the localization
of the nanofillers/BP blend is also reported. The review article discusses recent
progress from 2014 up to 2019 on filler localization of BP blend
nanocomposites
The effect of filler localization on the properties of biopolymer blends, recent advances: A review
No full textIdentifying critical HR competencies for post-pandemic HR professionals
No full textThe COVID-19 pandemic brought unprecedented changes to the workplace, forcing organisations to adapt quickly to remote work, flexible arrangements, and digitalisation. Human Resource (HR) professionals played a significant role in managing these transitions, ensuring employee well-being, and implementing new workplace policies and procedures. However, there is scant research on the competencies required by HR professionals to navigate the post-pandemic work environment successfully. This study aims to identify the critical HR competencies needed for HR professionals to thrive in the post-pandemic era. To address the research objective, a qualitative research approach was employed, which involved semi-structured interviews conducted online and face-to-face with nine HR professionals who participated in the study. The data were analysed using thematic analysis. The findings provide insights for HR professionals and organisations to develop effective HR practices and successfully support the transition to the post-pandemic work environment. Six themes emerged from the study: the Role of HR in the Post-Pandemic Work Environment, HR Competencies in the Post-Pandemic Work Environment, the Evolution of Critical HR Competencies in the Post-Pandemic Era, Challenges Faced by HR Professionals, Future-Proofing HR Competencies and Roles, and Professional Development. Given the limited existing studies on HR competencies in the post-pandemic period, further research is recommended in this area
Pursuing organisational excellence as a key driver in achieving organizational learning
No full textThesis (MPhil)--Stellenbosch University, 2012.ENGLISH ABSTRACT: Volatility, globalisation, turbulence and constant change are some of the challenges facing
the business environment today. Companies have proposed and tested many strategies to
cope with the unpredictable world of business. In this thesis, a project by an anonymous
South African company (The Company) to respond by improving organisational excellence is
analysed and evaluated against its success in fostering organisational learning.
The Company initiated a project in which Lean Manufacturing, Six Sigma and Clear
Leadership Engagement were combined in search of operational excellence.
In Chapter 1, the context is set out. The research question is formulated as follows: to what
extent does organisational learning depend on organisational excellence?
Chapter 2 discusses and defines key process concepts. These are: Lean Manufacturing, Six
Sigma, Lean Six Sigma and Clear Leadership Engagement Models. The chapter also outlines
the key practices and the shortcomings of each process.
Chapter 3 discusses and defines the conceptual building blocks of the thesis. These are the
notions of organisational learning and learning organisation. Tools used to diagnose whether
an organisation is learning are introduced together with an Organisational Learning model to
be used to assess the relationship between Organisational Learning and Operational
Excellence.
Chapter 4 focuses on the project of the Company – the Operational Excellence “journey”.
How the journey was conceived, the players were involved and steps taken to drive it are
described.
In Chapter 5, the combination of Lean Six Sigma, Lean Manufacturing and the engagement
models that the Company used, is assessed. The chapter attempts to unravel the reasons
behind this combination and determine how this combination worked in practice. It is through
this chapter that an attempt is made to explain the logic of this unusual combination. Other
businesses have implemented different forms of improvement in isolation, but it is rare to
find a company that combines operational improvement methodologies with an engagement
model.
In Chapter 6, all the theories and empirical evidence come together. In this chapter, the
relationship between Pursuing Operational Excellence (POE) and Organisational Learning is
tested. The author uses the seven salient characteristics of learning organisations, distilled by
the researcher, to prove the positive relationship between Organisational Learning and
Operational Excellence. Through this chapter, the researcher answers the question whether a
positive link exists between POE and Organisational Learning.
It was clear from the research that there is indeed a positive link between POE and
Organisational Learning. What the research could not determine is the degree or the rate of
learning linked to POE, or what percentage of learning the organisation achieved over a
period of time.AFRIKAANSE OPSOMMING: Volatiliteit, globalisering, turbulensie en konstante verandering is ‘n uitdaging waarmee die
sake-omgewing deesdae te doen kry. Baie strategieë is voorgestel en getoets deur
maatskappye ten einde by te bly in die onvoorspelbare sake-wêreld. In hierdie tesis word ‘n
projek wat in ‘n anonieme Suid-Afrikaanse maatskappy (The Company) uitgevoer is om op
die uitdagings te reageer, by wyse van ‘n dryf na operasionele uitnemendheid, geanaliseer en
geëvalueer aan die hand van die mate waarin sodanige aksies organisatoriese leer bevorder
het.
The Company het ‘n projek geloods waarin Lean Manufacturing, Six Sigma en Clear
Leadership Engagement gekombineer is op soek na operasionele uitnemendheid.
In Hoofstuk 1 word die konteks uiteengesit en die navorsingsvraag geformuleer as die vraag
in watter mate organisatoriese leer deur operasionele uitnemendheid bepaal word.
In Hoofstuk 2 word die kern prosesbegrippe bespreek en gedefinieer. Dit is: Lean
Manufacturing, Six Sigma, Lean Six Sigma en Clear Leadership Engagement models. Die
hoofstuk gee ook ’n oorsig oor die hoofpraktyke en tekortkominge van elke model.
Hoofstuk 3 bespreek die konseptuele basis van die navorsing. Dit is die konsepte:
Organisatoriese Leer en Lerende Organisasie. Instrumente om te diagnoseer of ’n organisasie
leer, word voorgestel, asook ’n model van Organisatoriese Leer wat gebruik sal word om die
verband tussen Organisatoriese Leer en Operasionele Uitmuntendheid te bepaal.
Hoofstuk 4 fokus op die projek wat The Company onderneem het. In hierdie hoofstuk word
die “reis” na operasionele uitnemendheid beskryf; hoe dit ontstaan het, die rolspelers wat
betrokke was en die stappe wat op die reis geneem is.
In Hoofstuk 5 beoordeel die kombinasie van Lean Six Sigma, Lean Manufacturing en die
engagement modelle wat deur die Company gebruik is. Die hoofstuk probeer ontrafel wat die
motivering vir hierdie kombinasie is en hoe dit in die praktyk uitgewerk het. In die hoofstuk
word gepoog om die logika van hierdie ongewone kombinasie te peil. Ander ondernemings
het verskillende vorms van verbetering in isolasie geïmplementeer, maar dit is selde dat ’n
mens ’n maatskappy vind wat operasionele verbeteringsmetodologieë kombineer met ’n
engagement model.
In Hoofstuk 6 kom al die teorieë en empiriese gegewens bymekaar. Dit is in hierdie hoofstuk
waar die verhouding tussen die nastrewing van Operasionele Uitnemendheid en
Organisatoriese Leer getoets word. Die navorser gebruik die sewe kenmerke van Lerende
Organisasies wat tevore geïdentifiseer is om ’n positiewe verband tussen Organisatoriese
Leer en Operasionele Uitnemendheid aan te toon.
Uit die navorsing was dit duidelik dat daar ’n positiewe verband is tussen die nastrewing van
Operasionele Uitnemendheid en Organisatoriese Leer. Maar, wat die navorsing nie kon
beantwoord nie, is die graad of spoed van leer wat met die nastrewing van Operasionele
Uitnemendheid verbind kan word, of watter persentasie leer die organisasie oor ’n gegewe
tydperk bereik het.Master
Structural, Magnetic, and Electron Spin Resonance Properties of Nickel Nanoferrites Synthesized by High‐Energy Ball Milling
No full textNanocrystalline NiFe2O4 was synthesized using high‐energy ball milling. The effect of milling time on structural and magnetic properties was investigated. X‐ray diffraction results revealed a progressive transformation from mixed NiO–Fe2O3 precursor phases to a single‐phase cubic spinel NiFe2O4 structure with crystallite sizes ranging from 33.64 to 41.17 nm. The scanning electron microscopy showed small grains attaching to big grains for 1 h milled sample. The big grains disappear with increasing milling time. Homogeneous nanoparticles, spherically shaped and agglomerated nanoparticles, were observed for samples that were milled for 5, 10, and 15 h. Energy‐dispersive X‐ray spectroscopy confirmed the presence of all expected elements. The nature of M–H loops for all the samples shows soft ferromagnetic behavior. The Electron spin resonace (ESR) results revealed the reduction of resonance field with increasing milling time. The g‐values increased with milling time. The obtained high g‐values make NiFe2O4 oxides suitable for applications in high‐frequency devices. The spin–spin (τ1) relaxation time decreased with increasing milling, time while the spin–lattice (τ2) showed improvement
