There is increasing interest in rare earth (RE) doped nanoparticles (NPs) due to their sharp absorption and photoluminescence (PL) in the near infrared (NIR) spectral region. These NIR based ...nanoparticles (NPs) could allow biological imaging at substantial depths with enhanced contrast and high spatial resolution due to the absence of auto fluorescence in biological samples under infrared excitation. Here, we present the highly efficient infrared photoluminescence in GdF₃:Nd(3+) nanoparticles under 800 nm excitation within the hydrodynamic size limitations for bio-applications. The downconversion (Stokes emission) absolute quantum yields (QY) in powder, polymaleic anhydride-alt-1-octadicene (PMAO) coated powder and colloidal solutions have been investigated. QY measurements have revealed that downconversion (Stokes emission) QYs of approximately 5 ± 2 nm sized GdF₃:1% Nd(3+) colloidal NPs are 2000 times higher than those of efficient upconversion (UC) particles NaYF₄:20% Er/2% Yb of the same size. Furthermore, the utility of these NIR emitting nanoparticles for bioimaging probes has been demonstrated by confocal imaging and spectroscopic study.
A new radial time projection chamber based on Gas Electron Multiplier amplification layers was developed for the BONuS12 experiment in Hall B at Jefferson Lab. This device represents a significant ...evolutionary development over similar devices constructed for previous experiments, including cylindrical amplification layers constructed from single continuous GEM foils with less than 1% dead area. Particular attention had been paid to producing excellent geometric uniformity of all electrodes, including the very thin metalized polyester film of the cylindrical cathode. This manuscript describes the design, construction, and performance of this new detector.
An assessment of liquefaction potential for the Kathmandu Valley considering seasonal variability of the groundwater table has been conducted. To gain deeper understanding seven historical ...liquefaction records located adjacent to borehole datapoints (published in SAFER/GEO-591) were used to compare two methods for the estimation of liquefaction potential. Standard Penetration Test (SPT) blowcount data from 75 boreholes inform the new liquefaction potential maps. Various scenarios were modelled, i.e., seasonal variation of the groundwater table and peak ground acceleration. Ordinary kriging, implemented in ArcGIS, was used to prepare maps at urban scale. Liquefaction potential calculations using the methodology from (Sonmez, Environ Geol 44:862–871, 2003) provided a good match to the historical liquefaction records in the region. Seasonal variation of the groundwater table is shown to have a significant effect on the spatial distribution of calculated liquefaction potential across the valley. The less than anticipated liquefaction manifestations due to the Gorkha earthquake are possibly due to the seasonal water table level.
Using the integrating sphere technique the absolute quantum yield measurements of the visible emission bands at 550, 650 and 750nm in Yb/Ho doped M2O2S (M=Y, Gd, La) upconversion phosphor have been ...reported for the first time. Observations show that the 750nm emission in La2O2S doped with 1mol% each of Yb and Ho yield the highest efficiency of 0.12% followed by green emission which is 0.065% with 9.5% Yb and 0.5% Ho in the same host. The red emission in La2O2S, Y2O2S are nearly 6 times weaker than green emission, whereas in Gd2O2S it is 14 times less efficient making Gd2O2S doped with 4.5mol% Yb and 0.5mol% Ho as the most efficient single color green upconvertor among all three host compositions studied.
► Upconversion efficiency of YbHo doped metal oxysulphide was measured for the first time. ► 756nm emission band shows the highest efficiency in all phosphors under 980nm excitation. ► Gd2O2S:Yb(4.5%)/Ho(0.5%) shows the best green upconversion efficiency. ► Green upconversion efficiency shows increasing tendency with Yb/Ho ratio in YOS and LOS.
In mild climatic conditions, residential houses are often ventilated by windows on a single exterior wall. The resulting airflow in single-sided naturally ventilated spaces is complex due to the ...involvement of buoyancy and wind driven forces that can reinforce, or restrict, the buoyancy-driven flow. The consequence of these effects on indoor flow-fields, and particularly convective heat transfer on the floor, needs examination. To understand the influence of wind conditions, this work utilized computational fluid dynamics to examine the flow in, and heat transfer from the floor of, a single-sided partly open air-filled cubical enclosure. The results indicate that both the indoor flow-field and convective heat transfer at the floor are strongly influenced by the outside wind conditions. As such, there is a significant scope to improve the relationships used to estimate the convective heat transfer from the floor of naturally ventilated buildings by including the effect of outdoor wind conditions.
Removal of phosphate from wastewater is necessary for the safety of public health and environmental protection. The present study used an easily available and affordable biosorbent obtained from the ...pomegranate peel for the excision of phosphate from water. The biosorption behavior of raw pomegranate peel powder (RPGPP) was found negligible. The RPGPP was further saponified with Ca(OH).sub.2 followed by Fe(III) loading to obtain Fe(III)-loaded pomegranate peels (Fe(III)-PGPP), which was then employed for the phosphate uptake. Fourier transform infrared spectroscopy (FTIR), energy dispersive X-ray (EDX) spectroscopy, scanning electron microscopy (SEM), and X-ray diffraction (XRD) were used to characterize the biosorbent. The batch adsorption test was used to evaluate the adsorption viability of biosorbents for removing phosphate from aqueous solution. Fe(III)-PGPP was determined to have a pH.sub.PZC of 5.40. The experimental data were best explained by the Langmuir isotherm and pseudo-second-order kinetic model. Fe(III)-PGPP had the largest phosphate biosorption capacity of 99.30 mg g.sup.-1 at the optimum pH of 3.0 and 2.5 hours of contact time. From the results obtained, Fe(III)-PGPP adsorbent can be regarded as an effective and cost-efficient material for the treatment of phosphate-anion-contaminated water. Keywords wastewater treatment, phosphate, biomass, pomegranate peel, biosorbent
Secondary electron yields of (110) copper surfaces, covered with either carbon, nitrogen, or their dioxides, have been studied by employing combined first principles methods for the material ...properties and Monte Carlo simulations for electron transport. Furthermore, by studying electron transport inside the Cu system and modeling the power loss taking account of the inelastic electron scattering within the material, changes in the thermal energy of the system have been modeled. The physical reasons behind the increase and decrease of the yield for each system from an electronic perspective are discussed. In agreement with results observed in studies of secondary electron emission, it is shown that the formation of C
2
and N
2
monolayers reduce the secondary electron yields, while CO
2
and NO
2
increase the yield significantly. It is demonstrated that in the case of C
2
and N
2
formation, changes in the surface electronic barrier reduce the probability of electron escape from the Cu surface, resulting in lower secondary electron emission. Formation of CO
2
and NO
2
, on the other hand, reduce the electronic barrier effects. In addition, due to weak bonding of the CO
2
layer with the Cu host, the surface provides an additional source of secondary electrons resulting in higher electronic emission yield. Moreover, the NO
2
adsorbate creates a surface electric field that changes the surface electron energy and increases the electron escape probability. Additionally, it is verified that thermal change in the system is negligible and so during secondary electron emission measurements, negligible (if any) surface adsorption or desorption could occur.
A total of 11 multidrug-resistant
clinical isolates were obtained in Nepal. Four of these isolates harbored genes encoding one or more carbapenemases (DIM-1, NDM-1, and/or VIM-2), and five harbored ...genes encoding a 16S rRNA methyltransferase (RmtB4 or RmtF2). A novel RmtF variant, RmtF2, had a substitution (K65E) compared with the same gene in RmtF. To our knowledge, this is the first report describing carbapenemase- and 16S rRNA methyltransferase-coproducing
clinical isolates in Nepal.
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