Spin-Reorientation and M?ssbauer Study of Orthoferrite TbFe0.75Mn0.25O3

The crystallographic and magnetic properties of TbFe_0.75Mn_0.25O₃ powder were characterized by x-ray diffraction (XRD), Mössbauer spectroscopy, and vibrating-sample magnetometry (VSM). The crystal structure was found to be orthorhombic (space group Pbnm) with lattice constants a ₀=5.317 Å, b ₀=5.604 Å, and c ₀=7.598 Å, respectively. Mössbauer spectra of TbFe_0.75Mn_0.25O₃ have been taken at various temperatures ranging from 4.2 to 550 K. For Mössbauer spectra, we have fitted the spectra to a model based on a random distribution of Fe and Mn ions on the octahedral sites. The magnetic hyperfine fields of the four pattern (B ₀,B ₁,B ₂,B ₃) at 4.2 K are found to be H _hf=553, 544, 535, and 527 kOe, respectively. Isomer shift at room temperature is 0.25?C0.26 mm/s, which means that the valence state of Fe ions is ferric (Fe³⁺). A sudden change in both the magnitude of magnetic hyperfine field and its slope between 150 and 220 K suggests that magnetic phase transition related to the spin ordering takes place abruptly. The Néel temperature was determined to be T _N=550±5 K. The inflection points arising from a spin reorientation in the temperature dependence of the magnetic moment is observed. Its spin-reorientation transition is 70 K lower than that of 250 K for pure TbFeO₃.     

A comparison of cross-training policies in different job shops

This research compares a set of cross-training policies represented by different numbers of cross-trained workers, additional skills per cross-trained worker, and additional machines. The policies are evaluated in job shops, represented by different efficiency losses, labour utilization, variability in processing times, and worker absenteeism. Our results show that adding one machine in each department and cross-training one or two workers from each department with one additional skill is generally sufficient to realize most of the benefits of cross-training. Cross-training is thus beneficial in most job shops, unless the cost of the minimal training and spare machines is high. Our results also show that the value of cross-training and adding machines depends very much on the environment, and it is better to spread cross-training over more workers than to train a few workers with more skills.     

Effect of millimeter waves on the microbiological and physicochemical properties of Korean rice wine <Emphasis Type="Italic">Makgeolli</Emphasis>

Millimeter waves are electric waves between 30 and 300 GHz. They are known to affect microbial growth. Here, the effects of millimeter waves on the microbiological and physicochemical properties of Makgeolli irradiated during fermentation were investigated. Millimeter waves at 60 and 70 GHz were used, and the fermentation was carried out at 30°C. The numbers of both lactic acid bacteria and yeasts have changed with similar pattern each then during the fermentation, but the effect of milimeter wave treatment was not critical as growth patterns were independent of both irradiation period and wave frequency. Furthermore, pH and total acidity did not change during fermentation. Although irradiation drastically increased sugar production during the initial stage of fermentation, the change was not frequency dependent. At the end of fermentation, the alcohol content in irradiated Makgeolli was definitely higher than that in un-irradiated Makgeolli, and the difference was frequency dependent.     

Imaging technique for quantification of oil palm fruit ripeness and oil content

We investigated a non‐destructive technique for measuring the colour of oil palm fruit (Elaeis guineensis) bunches at different stages of maturity and correlating the colour data with the oil content in the fruit bunch. A digital red, green and blue (RGB) camera was used to capture the image of palm fruits and hue histograms were then constructed from mathematically transformed RGB data. The dominant hue peaks were then correlated to the oil content of fresh fruit bunches (FFBs). The study showed that the results obtained were influenced by FFB that possessed different expressions of colour changes during the ripening process. The results obtained from colour image analyses were not satisfactory – the correlation between hue peak and FFB oil content was r = 0.7933. However, when FFB having the same ripening patterns were analysed, the correlation was very much improved with r = 0.9519. Thus, statistical evaluation showed that the digital imaging technique for determining FFB oil content can be successfully used on a homogeneous population of palms that display similar change of colour during the ripening process. Practical applications : The ability to correctly identify physiological maturity and harvest maturity of palm fruits by phenological characteristics will ensure timely harvest to avoid cutting of either under‐ and over‐ripe fruits. The Malaysian Palm Oil Board [MPOB] 1 has published an oil palm fruit grading manual outlining 16 classifications for grading FFB ripeness and quality. However, the FFB grading methods are still very subjective, i.e. depend on the judgement, experience and skill of a person. In addition, the methods do not provide quantitative information about the oil in the FFB. The method reported in this paper allows for rapid screening of FFB ripeness, and relate it to oil content in the FFB and accordingly the amount of oil that can be extracted from a consignment of FFB. Since it only takes a few seconds to capture signals, the system could be incorporated for on‐line monitoring of FFB ripeness and oil content thereof.     

Red phosphorescent organic light-emitting diodes based on the simple structure

We demonstrated that the simple layered red phosphorescent organic light-emitting diodes (OLEDs) are possible to have high efficiency, low driving voltage, stable roll-off efficiency, and pure emission color without hole injection and transport layers. We fabricated the OLEDs with a structure of ITO/CBP doped with Ir(pq)2(acac)/BPhen/Liq/Al, where the doping concentration of red dopant, Ir(pq)2(acac), was varied from 4% to 20%. As a result, the quantum efficiencies of 13.4, 11.2, 16.7, 10.8 and 9.8% were observed in devices with doping concentrations of 4, 8, 12, 16 and 20%, respectively. Despite of absence of the hole injection and transport layers, these efficiencies are superior to efficiencies of device with hole transporting layer due to direct hole injection from anode to dopant in emission layer.     

Highly efficient red phosphorescent organic light-emitting devices using iridium(III) complexes based on 2-(biphenyl-3-yl)quinoline derived ligands

Red phosphorescent emitters were synthesized based on Ir(III) phenylquinoline complexes for applications to OLEDs. Ir(III) complexes 1-3 were based on 2-(biphenyl-3-yl)-quinoline units connected to various phenyl groups such as 5-phenyl, 5-(4-fluorophenyl), and 6-phenyl groups. The EL efficiencies were quite sensitive to the structural features of the dopants in the emitting layers. In particular, a high-efficiency red OLED was fabricated using complex 1 as the dopant in the emitting layer. This OLED showed a maximum luminance, luminous efficiency, power efficiency, external quantum efficiency and CIE(x,y) coordinates of 21,600 cd/m2 at 16 V, 11.80 cd/A at 20 mA/cm2, 3.57 Im/W at 20 mA/cm2, 10.90% at 20 mA/cm2, and (x = 0.63, y = 0.32) at 12 V, respectively.     

Efficient triplet exciton confinement of blue- and white-organic light emitting diodes using a new host material

We have demonstrated lower driving voltage and efficient blue phosphorescent organic light emitting diodes (PHOLEDs) using iridium(III) bis[(4,6-di-fluoropheny)-pyridinato-N,C2] picolinate (Flrpic) doped in new host material 9-(4-(triphenylsilyl)phenyl)-9H-carbazole (SPC) and 2,2',2"-(1,3,5-benzenetryl)tris(1-phenyl)-1H-benzimidazol (TPBi) as double-emitting layer (D-EML) system. The D-EML was employed to have good electron transportability and exciton confinement. Additionally, we fabricated white organic light-emitting diode (WOLED) using a phosphorescent red emitter; bis(2-phenylquinolinato)-acetylacetonate iridium III (Ir(pq)2acac) doped in SPC and TPBi as D-EML. The properties of white device exhibited a maximum luminous efficiency of 19.03 cd/A, a maximum external quantum efficiency of 9.91%, and a maximum power efficiency of 12.30 lm/W. It also showed white emission with CIE(x,y) coordinates of (x = 0.38, y = 0.37) at 8 V.     

Mhc class I and non-class I gene organization in the proximal H2-M region of the mouse

A bacterial artificial chromosome (BAC) contig was constructed across the proximal part of the H2-M region from the major histocompatibility complex (Mhc) of mouse strain 129 (H2bc). The contig is composed of 28 clones that span approximately 1 megabasepair (Mb), from H2-T1 to Mog, and contains three H2-T genes and 18 H2-M genes. We report the fine mapping of the H2-M class I gene cluster, which includes the previously reported M4-M6, the M1 family, the M10 family, and four additional class I genes. All but two of the H2-M class I genes are conserved among haplotypes H2k, H2b, and H2bc, and only two genes are found in polymorphic HindIII fragments. Six evolutionarily conserved non-class I genes were mapped to a 180 kilobase interval in the distal part of the class I region in mouse, and their order Znf173-Rfb30-Tctex5-Tctex6- Tctex4-Mog was found conserved between human and mouse. In this Znf173-Mog interval, three mouse class I genes, M6, M4, and M5, which are conserved among haplotypes, occupy the same map position as the human HLA-A class I cluster, which varies among haplotypes and is diverged in sequence from the mouse genes. These results further support the view that class I gene diverge and evolve independently between species.     

Pyridine/isoquinoline-carbazole containing bipolar host materials for green phosphorescent organic light-emitting diodes

We demonstrated the electroluminescent properties of bipolar host materials such as 9-(3-(6-methylpyridin-2-yl)phenyl)-9H-carbazole (Czpmpy), 9-(6-phenylpyridin-2-yl)-9H-carbazole (Czppy), and 9-(3-(isoquinolin-1-yl)phenyl)-9H-carbazole (Czpiq). Particularly, by using host (Czpiq) and dopant (bis[2-(1,1',2',1"-terphen-3-yl)pyridinato-C,N]iridium(III) (tphpy),2Ir(acac)) as the emitting layer, a green phosphorescent OLED was fabricated, showing a maximum luminance of 12780 cd/m2 at 10 V, maximum luminous efficiency of 45.0 cd/A, power efficiency of 47.1 Im/W, maximum external quantum efficiency of 12.3%, and CIE x, y coordinates of (0.34, 0.58) at 8 V.     

Tertiary hierarchically structured TiO2 for CdS quantum-dot-sensitized solar cells

A tertiary hierarchically structured mesoporous spherical TiO₂ (with a diameter of 1190 ± 60 nm) was synthesized by combining the sol–gel and the subsequent solvothermal treatment, and applied to CdS quantum-dot-sensitized solar cells (QDSSCs). This mesoporous spherical (MS) TiO₂ offers a high surface area (76.02 m² g⁻¹), a high internal reflectance in the visible region and a pore accessibility. A conversion efficiency of 1.9% was achieved by CdS QDSSCs composed of the MS TiO₂ photoanode, which corresponds to ∼58% improvement as compared with the values obtained from the conventional devices made with 20-nm-sized nanocrystalline TiO₂ under AM 1.5 illumination of 100 mW cm⁻². Thus, the MS TiO₂ can be a promising candidate for the photoanode material of QDSSCs.