Proučavanje luminescencije uzbudom naviše u nanokristalima BaTiO3: Ho3+

Visible up-conversion emissions at 435, 545, 580, 675 and 690 nm and 437, 547, 575 and 675 nm have been obtained from BaTiO3 doped with 4 % Ho3+ ions in two different forms of the prepared samples, powder and thin film, under 808 nm laser diode excitation emissions. Combined with the energy level structure of Ho3+ ions and the kinetics of the visible emissions, the up-conversion mechanism has been analyzed and explained. The blue, green and red emissions of both samples have been attributed to the ground state-directed transition from 5F1, 5S2 and 5F5 states, respectively, which are populated through excited state absorption on 808 nm excitation. Nano-structure pure barium titanate and doped with different concentrations of Ho3+ ions in the form of powder and thin films have been prepared by so-gel technique, using barium acetate (Ba(CH3CHOO)2) and titanium isopropoxide (Ti((CH3)2CHO)4) as precursors. The thin films were prepared by spin-coating sol-gel method. The as-grown thin film and powders were found to be amorphous, which crystallized to the tetragonal phase after synthesization at 750 °C in air for 30 minutes. The crystallite size of thin film and powder samples both doped with 4 % Ho3+ ions, were found to be equal to 11 and 16 nm, respectively.Uzbudom laserskom diodom na 808 nm postigli smo emisije u vidljivom području na 435, 545, 580, 675 i 690 nm, te na 437, 547, 575 and 675 nm, u BaTiO3 punjenom s 4 % Ho3+ iona u uzorcima dvaju oblika, prahu i tankom sloju. Uzimajući u obzir stanja iona Ho3+ i kinetiku emisije fotona, analizirali smo i objasnili mehanizam uzbude naviše. Emisije oba uzorka u plavom, zelenom i crvenom području pripisuju se prijelazima u osnovno stanje sa stanja 5F1, 5S2 odn. 5F5 koja se pune apsorpcijom fotona 808 nm u višim stanjima Ho3+ iona. Metodom sol-gel pripremili smo nanostrukturni čist barijum titanat i barijum titanat punjen s dvjema koncentracijama Ho3+ iona, kao prah i kao tanke slojeve. Rabili smo barijum acetat (Ba(CH3CHOO)2) i titanijev izopropoksid (Ti((CH3)2CHO)4) za njihovu pripremu. Tanke smo slojeve dobivali centrifugiranjem sol-gela. Svježe pripremljeni tanki slojevi i prah su amorfni, ali se kristaliziraju zagrijavanjem na 750 ◦C u zraku tijekom 30 minuta. Veličina kristalita u tankom sloju i prahu, svaki punjen s 4 % Ho3+ iona, iznosi 11 odn. 16 nm

Proučavanje luminescencije uzbudom naviše u nanokristalima BaTiO3: Ho3+

Visible up-conversion emissions at 435, 545, 580, 675 and 690 nm and 437, 547, 575 and 675 nm have been obtained from BaTiO3 doped with 4 % Ho3+ ions in two different forms of the prepared samples, powder and thin film, under 808 nm laser diode excitation emissions. Combined with the energy level structure of Ho3+ ions and the kinetics of the visible emissions, the up-conversion mechanism has been analyzed and explained. The blue, green and red emissions of both samples have been attributed to the ground state-directed transition from 5F1, 5S2 and 5F5 states, respectively, which are populated through excited state absorption on 808 nm excitation. Nano-structure pure barium titanate and doped with different concentrations of Ho3+ ions in the form of powder and thin films have been prepared by so-gel technique, using barium acetate (Ba(CH3CHOO)2) and titanium isopropoxide (Ti((CH3)2CHO)4) as precursors. The thin films were prepared by spin-coating sol-gel method. The as-grown thin film and powders were found to be amorphous, which crystallized to the tetragonal phase after synthesization at 750 °C in air for 30 minutes. The crystallite size of thin film and powder samples both doped with 4 % Ho3+ ions, were found to be equal to 11 and 16 nm, respectively.Uzbudom laserskom diodom na 808 nm postigli smo emisije u vidljivom području na 435, 545, 580, 675 i 690 nm, te na 437, 547, 575 and 675 nm, u BaTiO3 punjenom s 4 % Ho3+ iona u uzorcima dvaju oblika, prahu i tankom sloju. Uzimajući u obzir stanja iona Ho3+ i kinetiku emisije fotona, analizirali smo i objasnili mehanizam uzbude naviše. Emisije oba uzorka u plavom, zelenom i crvenom području pripisuju se prijelazima u osnovno stanje sa stanja 5F1, 5S2 odn. 5F5 koja se pune apsorpcijom fotona 808 nm u višim stanjima Ho3+ iona. Metodom sol-gel pripremili smo nanostrukturni čist barijum titanat i barijum titanat punjen s dvjema koncentracijama Ho3+ iona, kao prah i kao tanke slojeve. Rabili smo barijum acetat (Ba(CH3CHOO)2) i titanijev izopropoksid (Ti((CH3)2CHO)4) za njihovu pripremu. Tanke smo slojeve dobivali centrifugiranjem sol-gela. Svježe pripremljeni tanki slojevi i prah su amorfni, ali se kristaliziraju zagrijavanjem na 750 ◦C u zraku tijekom 30 minuta. Veličina kristalita u tankom sloju i prahu, svaki punjen s 4 % Ho3+ iona, iznosi 11 odn. 16 nm

Two-dimensional Vesicle dynamics under shear flow: effect of confinement

Dynamics of a single vesicle under shear flow between two parallel plates is studied using two-dimensional lattice-Boltzmann simulations. We first present how we adapted the lattice-Boltzmann method to simulate vesicle dynamics, using an approach known from the immersed boundary method. The fluid flow is computed on an Eulerian regular fixed mesh while the location of the vesicle membrane is tracked by a Lagrangian moving mesh. As benchmarking tests, the known vesicle equilibrium shapes in a fluid at rest are found and the dynamical behavior of a vesicle under simple shear flow is being reproduced. Further, we focus on investigating the effect of the confinement on the dynamics, a question that has received little attention so far. In particular, we study how the vesicle steady inclination angle in the tank-treading regime depends on the degree of confinement. The influence of the confinement on the effective viscosity of the composite fluid is also analyzed. At a given reduced volume (the swelling degree) of a vesicle we find that both the inclination angle, and the membrane tank-treading velocity decrease with increasing confinement. At sufficiently large degree of confinement the tank-treading velocity exhibits a non-monotonous dependence on the reduced volume and the effective viscosity shows a nonlinear behavior.Comment: 12 pages, 8 figure

Agricultural land-use change and disappearance of farmlands in Kaduna Metropolis-Nigeria

This study assessed agricultural land-use change in Kaduna metropolis. This study combined the use of remote sensing and geographic  information system (GIS) application to ascertain the rate of agriculturalland-use change from 1980 to 2012 in the study area. The four imageries (Landsat MSS 1980, Landsat TM 1990, Landsat ETM+ 2005 and Nigeria Sat X 2012) used were classified and compared to understand the rate and extent of agricultural land-use change during the different periods. The  findings revealed that the study area experienced a significant reduction inagricultural land and these leads to continued disappearance of farmlands. Lastly, the decrease in agricultural lands leads to loss of livelihood, reduction in food supply and increase poverty. This has raised so many concerns about the sustainability of Urban and Peri Urban Agriculture (UPA) production in the study area whereby the small scale farmers are the most affected.Key Words: Land-Use, Urban, Farmers, Remote Sensing, Geographic Information System (GIS) and Kaduna, Nigeri

New heat treatment to prepare high quality polycrystalline and single crystal MgB2 in single process

We report here on a new heat treatment to prepare both dense polycrystalline and single crystal MgB2 high quality samples in one single process. Resistivity measurements for polycrystalline part of the sample gives a residual resistivity ratio RRR=16.6 and a very low normal state resistivity rho(40K)= 0.28 microOhmcm. Both SEM and SQUID study on polycrystals reveal the high quality, dense character and well coupling of grain boundaries. On the other hand, the high quality single crystals have a unique shape that resembles the hexagonal crystal structure. SQUID measurements reveals very weak flux pinning character implying our single crystals to be very clean. In this study, we conclude that heat treatment is playing a major rule on the characteristics of both polycrystalline and single crystal MgB2. Samples are thoroughly characterized by x-ray, resistivity, dc SQUID and SEM

Ramanovi i fotoluminescentni spektri čistih i kositrom obogaćenih tankih slojeva CdS pripremljenih prskanjem i pirolizom

Thin films of CdS, pure and enriched with different concentrations of tin up to 6%, were prepared by the spray pyrolysis technique. All samples were prepared at the deposition temperature of 420 ◦C. The XRD diagnostic data of the investigated samples revealed the polycrystalline nature of the as-deposited samples. The main characteristic peaks of CdS appeared in both pure and enriched films prepared by all used methods. The enrichment of Sn has no effect on positions of the characteristic peaks. The observed effect of Sn enrichment is the change in peak broadening which increases with the increase of Sn concentration. The thickness values ranged from 0.65 up to 1.15 µm. The samples of pure CdS show a sharp absorption edge at about 2.43 eV. The absorption coefficient α of the investigated samples was calculated from transmission and reflection spectra. Photoluminescence measurements show red emission band of the as-deposited samples, which was quenched by Sn incorporation. This band is ascribed to the excess of Cd which was checked by the energy dispersive X-ray (EDX) spectrometry. Raman spectra of samples with different concentrations of Sn were studied. They show remarkable increase of intensity when increasing the film thickness and decreasing the Sn concentration.Metodom prskanja i pirolize pripremali smo čiste i do 6% kositrom obogaćene tanke slojeve CdS. Sve uzorke smo pripremali na temperaturi polaganja od 420 ◦C. XRD spektri ispitivanih uzoraka pokazuju polikristaliničnu strukturu. Glavni karakteristični vrhovi CdS vide se i u čistim i u obogaćenim uzorcima pripremljenim primijenjenim metodama. Obogaćenje kositrom nema utjecaja na položaje karakterističnih vrhova. Međutim, javlja se proširenje vrhova koje se povećava pri povećanim koncentracijama kositra. Izmjerene i izračunate debljine slojeva su u skladu. Debljine slojeva bile su između 0.65 i 1.15 µm. Uzorci CdS pokazuju oštar apsorpcijski rub na oko 2.43 eV. Apsorpcijske koeficijente α ispitivanih uzoraka smo izveli iz transmisijskih i refleksijskih spektara. Mjerenja fotoluminescencije pokazuju crvenu emisijsku vrpcu koja trne dodavanjem kositra. Ta se vrpca tumači viškom Cd što smo potvrdili disperzivnom rendgenskom spektrometrijom (EDX). Proučavali smo i Ramanove spektre uzoraka s raznim koncentracijama kositra. Oni pokazuju snažan porast intenziteta za slojeve veće debljine i manje koncentracije kositra

Ramanovi i fotoluminescentni spektri čistih i kositrom obogaćenih tankih slojeva CdS pripremljenih prskanjem i pirolizom

Thin films of CdS, pure and enriched with different concentrations of tin up to 6%, were prepared by the spray pyrolysis technique. All samples were prepared at the deposition temperature of 420 ◦C. The XRD diagnostic data of the investigated samples revealed the polycrystalline nature of the as-deposited samples. The main characteristic peaks of CdS appeared in both pure and enriched films prepared by all used methods. The enrichment of Sn has no effect on positions of the characteristic peaks. The observed effect of Sn enrichment is the change in peak broadening which increases with the increase of Sn concentration. The thickness values ranged from 0.65 up to 1.15 µm. The samples of pure CdS show a sharp absorption edge at about 2.43 eV. The absorption coefficient α of the investigated samples was calculated from transmission and reflection spectra. Photoluminescence measurements show red emission band of the as-deposited samples, which was quenched by Sn incorporation. This band is ascribed to the excess of Cd which was checked by the energy dispersive X-ray (EDX) spectrometry. Raman spectra of samples with different concentrations of Sn were studied. They show remarkable increase of intensity when increasing the film thickness and decreasing the Sn concentration.Metodom prskanja i pirolize pripremali smo čiste i do 6% kositrom obogaćene tanke slojeve CdS. Sve uzorke smo pripremali na temperaturi polaganja od 420 ◦C. XRD spektri ispitivanih uzoraka pokazuju polikristaliničnu strukturu. Glavni karakteristični vrhovi CdS vide se i u čistim i u obogaćenim uzorcima pripremljenim primijenjenim metodama. Obogaćenje kositrom nema utjecaja na položaje karakterističnih vrhova. Međutim, javlja se proširenje vrhova koje se povećava pri povećanim koncentracijama kositra. Izmjerene i izračunate debljine slojeva su u skladu. Debljine slojeva bile su između 0.65 i 1.15 µm. Uzorci CdS pokazuju oštar apsorpcijski rub na oko 2.43 eV. Apsorpcijske koeficijente α ispitivanih uzoraka smo izveli iz transmisijskih i refleksijskih spektara. Mjerenja fotoluminescencije pokazuju crvenu emisijsku vrpcu koja trne dodavanjem kositra. Ta se vrpca tumači viškom Cd što smo potvrdili disperzivnom rendgenskom spektrometrijom (EDX). Proučavali smo i Ramanove spektre uzoraka s raznim koncentracijama kositra. Oni pokazuju snažan porast intenziteta za slojeve veće debljine i manje koncentracije kositra

An integrated approach to supply chain risk analysis

Despite the increasing attention that supply chain risk management is receiving by both researchers and practitioners, companies still lack a risk culture. Moreover, risk management approaches are either too general or require pieces of information not regularly recorded by organisations. This work develops a risk identification and analysis methodology that integrates widely adopted supply chain and risk management tools. In particular, process analysis is performed by means of the standard framework provided by the Supply Chain Operations Reference Model, the risk identification and analysis tasks are accomplished by applying the Risk Breakdown Structure and the Risk Breakdown Matrix, and the effects of risk occurrence on activities are assessed by indicators that are already measured by companies in order to monitor their performances. In such a way, the framework contributes to increase companies' awareness and communication about risk, which are essential components of the management of modern supply chains. A base case has been developed by applying the proposed approach to a hypothetical manufacturing supply chain. An in-depth validation will be carried out to improve the methodology and further demonstrate its benefits and limitations. Future research will extend the framework to include the understanding of the multiple effects of risky events on different processe

The prevalence and spectrum of atypical glandular cells in Dubai hospital: A local experience

Objective : This study was undertaken to analyze the prevalence and spectrum of atypical glandular cells to investigate its clinical significance in our population. Study design : A 5 year retrospective review of atypical glandular cells diagnosed on ThinPrep pap test was performed. AGC were reported in 40 patients, who underwent colposcopy- directed biopsy, endocervical curettage and endometrial curettage to determine the cytological and histological correlations of AGC. Results : The prevalence of AGC was 0.2% out of 19836 patients. The patients age ranged from 29 to 81 years (mean age 49.4 years). Significant lesions were defined as Squamous Intraepithelial lesion (SIL), adenocarcinoma in situ (AIS) or invasive carcinoma. This included 2 invasive squamous cell carcinoma of the cervix, 2 high grade squamous intraepithelial lesions, 2 AIS, 5 adenocarcinoma of the cervix, two of which had low grade and high grade squamous intraepithelial lesions one of which was consistent with metastastic colonic carcinoma and 5 endometrial adenocarcinoma, one of which was suspicious of breast carcinoma. The chi-square value was significant at 99% confidence interval. Conclusion : AGC were associated with clinically significant lesions in 40% of our cases.. Significant endocervical glandular lesions occurred in younger women whereas the older women had endometrial lesions.. Patients with AGC should be followed up for a substantial period despite initial negative histological findings

Maternal serum CA-125 repeated measurement during pregnancy and how to use as a prognostic factor of first trimester pregnancy outcome

Background: The aim of this study was to estimate the prognostic efficacy of repeated measurement of maternal serum CA125 in first trimester threatened miscarriage.Methods: Prospective case control study was conducted in the outpatient clinic. 100 pregnant women were divided into 50 women with normal course of pregnancy, and the other 50 were subdivided into 25 pregnant women with lower abdominal pain without vaginal bleeding and 25 presented with minimal vaginal bleeding. Repeated measuring of serum CA125 was done for each case on the 5th, 10th weeks of gestation.Results: Findings of this study suggested the possibility of using serum CA-125 for determining the prognosis of first trimester threatened miscarriage with cut-off value of CA125 38.25 U/ml on the 5th week of gestation and 53 U/ml on the 10th week of gestation in patients presented with pain only but in patients presented with minimal vaginal bleeding the cut-off value of CA125 on the 5th week of gestation become 45.6 U/ml and 68 U/ml on the 10th week of gestation.Conclusions: CA125, on its own, can discriminate between continued and non-continued pregnancy.