Short communication: Comparison of 3 solid digesta passage markers in dairy cows.

This study investigated the usefulness of acid-detergent fiber-bound (15)N [acid detergent insoluble (ADI)-(15)N] as a solid digesta passage marker in dairy cows compared with chromium (Cr) and ytterbium (Yb) (as labeled fiber or forage, respectively). Intrinsically (ADI-(15)N) or extrinsically (Cr, Yb) labeled alfalfa hay was pulse-dosed intraruminally to 7 lactating dairy cows. Following marker administration, spot fecal samples were collected for up to 72 h for marker analyses. Urine and milk samples were also collected and analyzed for Yb and Cr. Fecal marker excretion data were processed using 2-compartment mathematical age-dependent/age-independent (Gn→G1) models. The rate of passage of the marker in the first, age-dependent compartment tended to be slower for Yb compared with Cr and ADI-(15)N, which resulted in a trend for longer mean retention time (MRT) in this compartment when Yb was used as a marker (19.0 h) compared with Cr and ADI-(15)N (14.5 and 13.9h, respectively). The rate constant of marker disappearance for the second or age-independent compartment tended to be greater for Yb compared with Cr and ADI-(15)N, which led to a shorter MRT of Yb in this compartment (15.6) versus ADI-(15)N (32.1) and Cr (24.8h). The cumulative MRT was greater for ADI-(15)N versus Cr and Yb (46.0, 39.3, and 34.4h, respectively). Total MRT of marker tended to be greater for ADI-(15)N than for Yb (46.6 vs. 36.6h, respectively). Urine and milk analyses data suggested no measurable losses of Yb along the digestive tract, but about 0.79% of Cr dosed intraruminally was secreted or excreted in milk and urine in the 48-h period following marker administration. Collectively, this study confirmed previous observations that ADI-(15)N can be used reliably as a solid digesta passage marker for ruminants, producing pre-duodenal and total-tract retention times similar to that of Cr-labeled fiber. Retention time in the age-independent compartment was underestimated when Yb was used as a marker, emphasizing the need to process forages to isolate fiber before labeling with Yb.

Near-infrared to near-infrared upconverting NaYF4:Yb3+,Tm3+ nanoparticles-aptamer-Au nanorods light resonance energy transfer system for the detection of mercuric(II) ions in solution.

A new luminescence resonant energy transfer (LRET) system has been designed that utilizes near-infrared (NIR)-to-NIR upconversion lanthanide nanophosphors (UCNPs) as the donor, and Au nanorods (Au NRs) as the acceptor. The UCNPs were excited by a near-infrared (980 nm) wavelength and also emitted at a near-infrared wavelength (804 nm) using an inexpensive infrared continuous wave laser diode. The Au NRs showed a high absorption band around 806 nm, which provided large spectral overlap between the donor and the acceptor. Hg(2+) ions were added to an aqueous solution containing the UCNPs and Au NRs that were modified with a Hg(2+) aptamer. Then, a sandwich-type LRET system was developed for the detection of Hg(2+) ions that had high sensitivity and selectivity in the NIR region. The method was successfully applied to the sensing of Hg(2+) ions in water and human serum samples.

High relaxivity and stability of a hydroxyquinolinate-based tripodal monoaquagadolinium complex for use as a bimodal MRI/optical imaging agent.

An octadentate ligand based on triazacyclononane and 8-hydroxyquinolinate/phenolate binding units leads to very soluble, highly stable lanthanide complexes. The monoaquagadolinium complex shows a high relaxivity as a result of the unusually long rotational correlation time, fast water exchange rate, and slow electronic relaxation. The ligand also acts as sensitizer of the near-IR luminescence emission of the Yb and Nd ions. It appears as an excellent candidate for use as a bimodal imaging agent.

Monte Carlo characterization of a new Yb-169 high dose rate source for brachytherapy application.

PURPOSE: The objective was to characterize a new Yb-169 high dose rate source for brachytherapy application. METHODS: Monte Carlo simulations were performed using the MCNP5 F6 energy deposition tallies placed around the Yb-169 source at different radial distances in both air-vacuum and water environments. The calculations were based on a spherical water phantom with a radius of 50 cm. The output from the simulations was converted into radial dose rate distribution in polar coordinates surrounding the brachytherapy source. RESULTS: The results from Monte Carlo simulations were used to calculate the AAPM Task Group 43 dosimetric parameters: Anisotropy function, radial dose function, air kerma strength, and dose rate constant. The results indicate a dose rate constant of 1.12 +/- 0.04 cGy h(-1) U(-1), anisotropy function ranging from 0.44 to 1.00 for radial distances of 0.5-10 cm and polar angles of 0 degrees-180 degrees. CONCLUSIONS: The data from the Yb-169 HDR source, Model M42, presented in this study show that this source compares favorably with another source of Yb-169, Model 4140, already approved for brachytherapy treatment.

Antibacterial effects of a monoporphyrinato ytterbium(III) complex and its free components on Staphylococcus aureus as determined by stop-flow microcalorimetry.

The antibacterial effect of Yb3+, the free porphyrin base 5,10,15,20-tetrakis(4-methoxyphenyl)porphyrin (H2TMP; 1), and the corresponding Yb3+ porphyrinato complex [Yb(III)(TMP)(H2O)3]+ Cl- (Yb(TMP); 2) towards Staphylococcus aureus was investigated by stop-flow microcalorimetry. By analyzing the obtained metabolic thermogenic curves, crucial parameters such as rate constant of bacterial growth (k), half inhibitory concentration (IC50), and generation time (t(G)) were determined. The antibacterial activities of the three compounds tested was 2>1>Yb3+, with an IC50 value of 273 mg/l for complex 2. The Yb3+ porphyrinato complex is proposed to benefit from synergetic effects of Yb3+ and the free porphyrin 1.

Kinetics-mediate fabrication of multi-model bioimaging lanthanide nanoplates with controllable surface roughness for blood brain barrier transportation.

Effective delivery of imaging agents or therapeutics to the brain has remained elusive due to the poor blood-brain barrier (BBB) permeability, resulting in the apparent risks of inefficient diagnosis and therapeutic agents for brain disease. Herein, we report on the surface roughness mediated BBB transportation for the first time. The lanthanide-based core/shell/shell structured NaYF4:Yb,Er@NaGdF4:Yb@NaNdF4:Yb nanoplates with controllable surface roughness and multi-model bioimaging features were synthesized and used to evaluate the surface roughness dependent BBB permeability without any surface bio-functionalization. By controlling the kinetics of the shell coating process, the hexagon-disc, multi-petals and six-petals nanoplates with different surface roughness can be obtained. Comparing with the NPs with less Ra and receptor-conjugated NPs, the obtained six-petals nanoplates with highest roughness exhibit excellent performance in BBB transportation and tumor targeting, which lay solid foundation for the diagnosis and the therapy of brain tumor.

Monte Carlo characterization of an ytterbium-169 high dose rate brachytherapy source with analysis of statistical uncertainty.

An ytterbium-169 high dose rate brachytherapy source, distinguished by an intensity-weighted average photon energy of 92.7 keV and a 32.015 +/- 0.009 day half-life, is characterized in terms of the updated AAPM Task Group Report No. 43 specifications using the MCNP5 Monte Carlo computer code. In accordance with these specifications, the investigation included Monte Carlo simulations both in water and air with the in-air photon spectrum filtered to remove low-energy photons below 10 keV. TG-43 dosimetric data including S(K), D(r, lamda), lambda, gL(r), F(r, lamda), phi an(r), and phi(an) were calculated and statistical uncertainties in these parameters were derived and calculated in the appendix.

Effects of Yb concentration on the spectroscopic properties of Yb: Y3Al5O12.

Yb:YAG single crystals with Yb doping concentration 5.4, 16.3, 27.1, 53.6, and 100 at.% were grown by the Czochralski process. The effects of Yb concentration on the absorption spectra (190-1100 nm), fluorescence spectra under 940 nm and X-ray excitation were studied. The concentration quenching of fluorescence was observed when the Yb doping concentration reaches to as high as 27.1at.% for Yb:YAG. Under 940 nm excitation, the influence of the self-absorption at 969 and 1029 nm on the fluorescence spectra is not evident when the Yb doping concentration is as high as 27.1at.%. However, it can greatly change the shape of fluorescence spectra of Yb:YAG when the Yb doping concentration reaches to above 53.6 at.%.

Rare earth elements in core marine sediments of coastal East Malaysia by instrumental neutron activation analysis.

A study was carried out on the concentration of REEs (Dy, Sm, Eu,Yb, Lu, La and Ce) that are present in the core marine sediments of East Malaysia from three locations at South China Sea and one location each at Sulu Sea and Sulawesi Sea. The sediment samples were collected at a depth of between 49 and 109 m, dried, and crushed to powdery form. The entire core sediments prepared for Instrumental Neutron Activation Analysis (INAA) were weighted approximately 0.0500 g to 0.1000 g for short irradiation and 0.1500 g to 0.2000 g for long irradiation. The samples were irradiated with a thermal neutron flux of 4.0×10(12) cm(-2) s(-1) in a TRIGA Mark II research reactor operated at 750 kW. Blank samples and standard reference materials SL-1 were also irradiated for calibration and quality control purposes. It was found that the concentration of REEs varies in the range from 0.11 to 36.84 mg/kg. The chondrite-normalized REEs for different stations suggest that all the REEs are from similar origins. There was no significant REEs contamination as the enrichment factors normalized for Fe fall in the range of 0.42-2.82.

Strong visible cooperative up-conversion emission in ZrO2:Yb3+ nanocrystals.

Blue, green, and red emission was observed under infrared excitation in ZrO2:Yb3+ nanocrystals prepared by the sol-gel process. The structural characterization was performed by using XRD and HRTEM, suggesting that the crystalline phase of the nanoparticles is controlled by the active ion concentration being mainly tetragonal for 2 mol% of dopant and mainly monoclinic for 0.5 mol%. The blue emission was explained in terms of the cooperative deexcitation of an Yb-Yb pair, while the green and red bands were associated with the up-conversion of traces of Er ion. The number of photons involved in the luminescence process is analyzed in order to confirm that cooperative emission is produced by the interaction of an Yb pair and that the green and red emission are the results of energy transfer between Yb-Er ions. The high efficiency of all bands is explained in terms of the high surface area of the nanoparticles.

Optical spectroscopy of Yb(3)Al(5)O(12) single crystal.

Yb(3)Al(5)O(12) single crystal has been grown by Czochralski (CZ) method. The absorption spectrum was investigated at low temperature and the electronic energy levels for (2)F(5/2) multiplet of Yb(3+) in YbAG was proposed. The up-conversion emission of the crystal under 940 nm diode pumping and the X-ray excited luminescence (XEL) features of the crystal were also studied.

[Determination of ten trace rare earth elements in the sample by atomic emission spectrometry].

This paper describes the determination of trace La, Ce, Pr, Nd, Sm, Gd, Tb, Dy, Yb and Lu in the sample, using carbon powder, potassium sulfate, barium sulfate, strontium sulfate, and scandium chloride as buffer, by atomic emission spectrometry (AES). Scandium was selected as internal standard line. Sample separation and chemical treatment were not required. The sample was directly loaded into ordinary electrode. The method is simple, rapid and accurate. The determination requirement and influence factors were studied. A new method was developed for the determination of ten rare earth elements, for which the detection limit is smaller than 0.030%, and the range of the recovery is 94%-105%. The results of these elements in standard sample are in agreement with certified values, and the RSD is smaller than 5% (n = 9). The method has been applied to the determination of ten rare earth elements with satisfactory results.

Determination of radionuclides in samples of middle-aged and older human femurs.

The paper presents the studies of the presence of gamma isotopes and (90)Sr in 19 middle-to old-aged human femur samples. The samples were taken up during routine orthopedic operations in 2012. The aim of the paper was determination of some radionuclides in human bones and estimation of radiation dose created by (90)Sr and (90)Y (in bones). The (137)Cs, (40)K, (226)Ra, (228)Th, (234)Th and (210)Pb isotopes were determined by gamma spectrometry. The above mentioned radionuclide contents were in the ranges: (137)Cs (0.04-1.45); (40)K (13-86); (226)Ra (1-21.5); (228)Th (1.4-40.2); (234)Th (0.4-5.7); (210)Pb (0.7-8.4) Bq/kg d.w. (90)Sr was assayed based on radiometric measurement of ingrown (90)Y. The (90)Sr content was in the range 0.27-1.85 Bq/kg d.w. Measurements of concentration of (90)Sr and (90)Y in bones were used to estimation of health risk by calculation of radiation dose. Adsorbed doses ranged from 2.7 · 10(-7) to 1.9 · 10(-6) Gy/y for (90)Sr and from 1.2 · 10(-6) to 8.3 · 10(-7) Gy/y for (90)Y.

Reaction analysis on Yb(3+) and DNA based on quantum dots: The design of a fluorescent reversible off-on mode.

Even though various strategies have reported for DNA detection, development of a simple, time-saving and specific fluorescent sensing platform still remains a desired goal. In this work, a quantum dots (QDs) based fluorescent reversible "off-on" mode was developed for sensitively recognition of herring sperm DNA (hsDNA). Firstly, in the "turn off" stage, the fluorescence of glutathione (GSH) capped CdTe QDs could be effectively quenched by ytterbium ion (Yb(3+)) was due to the occurrence of the electron transfer between Yb(3+) and the photoexcited QDs. And then, in the following "turn on" stage, with the effective binding reaction of Yb(3+) to hsDNA, the fluorescence intensity of GSH-capped CdTe QDs enhanced. Under the optimal conditions, the linear range of fluorescence versus the concentration of hsDNA was 0.010-12 µg/mL, and the detection limit was 3.033 ng/mL. In addition, the reaction mechanism among GSH-capped CdTe QDs, Yb(3+) and hsDNA were investigated by fluorescence spectroscopy, UV-vis spectrophotometry, fluorescence lifetime measurement and viscosity measurements. This analytical fluorescent reversible "off-on" pattern offered a way with good sensitivity and selectivity for the detection of hsDNA.

Rare earth elements as nonabsorbable fecal markers in studies of iron absorption.

The use of rare earth elements as nonabsorbable fecal markers for studies of iron absorption from sources labeled extrinsically with stable isotopes was evaluated. On 3 successive days 13 healthy fasting adults were given different stable isotopes of iron with samarium, ytterbium, or dysprosium. On day 1, three meals were given with 57Fe (1 mg per meal) plus samarium (0.33 mg per meal); on day 2, identical meals (taken with a calcium supplement to reduce iron bioavailability) were given with equivalent amounts of 58Fe-labeled iron and ytterbium; on day 3, a well-absorbed reference dose of 54Fe (3 mg) was given with 1 mg Dy. A complete fecal collection was carried out for 5-9 d and each stool was analyzed for rare earth elements by inductively coupled plasma-mass spectrometry and iron isotopes by thermal ionization quadrupole mass spectrometry. Mean recovery of rare earth elements was 101%, indicating that they are totally unabsorbed. The excretory pattern of the iron isotopes and the rare earth elements was very similar; the correlation coefficients between samarium and 57Fe, ytterbium and 58Fe, and dysprosium and 54Fe were 0.992, 0.989, and 0.988, respectively (P < 0.001). Iron absorption was calculated as the difference between isotope dose and fecal excretion. Mean (+/-SEM) iron absorption was 16.7 +/- 2.4%, 4.3 +/- 1.6%, and 40.3 +/- 3.1% on days 1-3, respectively. Predicted values estimated from the first 4 d of pooled feces, using the rare earth element recovery data to produce corrected figures for unabsorbed isotope, were in close agreement: 19.1 +/- 2.1%, 4.6 +/- 1.7%, and 40.8 +/- 3.1%, respectively (P < 0.001). With the diet of medium iron bioavailability and with the highly bioavailable reference dose it was possible to predict iron absorption accurately from only one or two stools, provided that they were sufficiently enriched with isotope and a rare earth element.

Monte Carlo aided room scatter corrections in the air-kerma strength standardization of 169Yb and 60Co brachytherapy sources.

For accurate evaluation of air-kerma strength, S(k), of 169Yb and 60Co brachytherapy sources, the present study reports Monte Carlo (MC) based corrections for (1) room scatter, and (2) departure from constant room scatter for rooms of various sizes. Correction for exponential attenuation of effective primary in air is also reported for the above sources. Values of S(k) per contained mCi, S(k)/A(c) predicted by MC calculations for 169Yb source (model X1267) with and without Ti K x-rays are 1.302 +/- 0.03% (this value is in excellent agreement with the published value reported by Piermattei et al) and 1.260 +/- 0.03% cGy cm2 h(-1) mCi(-1) respectively, and in the case of Cathetron 60Co source the value of S(k)/A(c) is 11.015 +/- 0.01% cGy cm2 h(-1) mCi(-1). It is observed that depending upon the position of the source with respect to the surrounding concrete scattering surfaces and set of d values, the assumption of constant room scatter has resulted in overestimation of S(k) that varied between 0.30% and 1.5% for the 169Yb source and only between 0.10% and 0.20% for the 60Co source.

Technical note: an algebraic method for calculating fecal output from a pulse dose of an external marker.

Fecal output estimates derived from a one-compartment, Gamma-2, age-dependent model were compared with estimates derived algebraically by computing the area under the marker excretion curve for lambs given a pulse dose of ytterbium-labeled forage. Lambs were fed one of four diets (as-fed basis): 100% alfalfa hay, 100% prairie hay, 50:50 alfalfa:sorghum grain, and 50:50 prairie hay:sorghum grain. For the one-compartment model, fecal output was calculated as the dose of Yb (micrograms) divided by the initial concentration in the compartment (micrograms of Yb/gram of DM) multiplied by the age-dependent rate constant (hours-1). For the algebraic method, fecal output was calculated as the dose of Yb divided by the area under the marker excretion curve ([micrograms of Yb/gram of fecal DM].hours), both with the full complement of fecal samples and with fecal samples collected at 12-h intervals. Fecal output estimated by the three methods did not differ (P > .15) from measured fecal output (total collection). Marker retention time calculated from the one-compartment, age-dependent model was numerically greater (P > .10) than retention time calculated algebraically (sum of concentration x time divided by sum of concentrations weighted for collection interval) for lambs fed all four diets. These results suggest that the area under the marker excretion curve generated from a pulse dose of Yb-labeled forage will provide estimates of fecal output that do not differ from those calculated from a one-compartment, age-dependent model.

Changes in forage quality, ingestive mastication, and digesta kinetics resulting from switchgrass maturity.

Five maturities of switchgrass hay harvested at 14-d intervals (vegetative through 20% heading) were fed to Hereford steers (297 kg) in a 5 x 5 Latin square. Relationships with switchgrass maturity were negative and quadratic (P < .05) for DMI and cubic (P < .05) for digestible DMI. Declines in apparent digestibilities of DM, ADF, and cellulose were cubic (P < .05), whereas these were quadratic (P < .05) for NDF, hemicellulose, and CP. Whole masticates from the least, mid, and most mature hays showed linear (P < .05) declines in DM concentration and IVDMD with increasing maturity, whereas NDF concentrations increased linearly (P < .05). Mean retention time of gastrointestinal DM increased linearly (P < .01) from 64 to 94 h from the least to the most mature hay, and the associated rate of passage declined linearly (P < .01) from 3.3 to 2.1%/h. Sieving of masticate DM showed a reduced proportion of large particles (> or = 2.8 mm) and an increased proportion of small particles (< or = .5 mm) with advancing forage maturity. More than 94% of the sieved fecal DM passed a 1.0-mm sieve, but particle sizes showed the same relationship with forage maturity as noted for masticate DM. This occurred despite the comminution from the rumination and digestive processes.

Real-time monitoring of Yb vapor density using an extended cavity violet diode laser.

Based on laser absorption spectroscopy (LAS), we developed a vapor density monitor for controlling the vaporization rate of Yb using a tunable diode laser. The laser source consisted of an extended cavity violet diode laser which has an emission wavelength of 398.8 nm coincident with the Yb absorption transition line, 6s(2) 1S(0)-6s6p 1P(1). The light emitted from the diode laser was transmitted across an atomic vapor column generated by heating the Yb metal, while the laser frequency was scanned across the atomic transition line. By comparing the amount of incident light to the amount of light transmitted after the light passed through the vapor column, the vapor density was determined using the Beer's law. From the experimental results, we demonstrated that the diode-laser-based LAS operated successfully for the real-time monitoring of the Yb vapor density.

[Spectral interferences of rare earth elements observed with a high resolution inductively coupled plasma atomic emission spectrometer. V. Spectral interferences of lutetium, thulium, yttrium and ytterbium as matrices].

The spectral interferences of Lu, Tm, Y and Yb (100 microns.mL-1, separately) as matrices on the other REEs (1 or 5 microns.mL-1) were observed with a high resolution ICP-AES with a grating of 3,600 grooves.mm-1. Totally 66 analytical lines of 15 REEs were selected as the prominent lines for spectral interference studies. The "Q" values and "the true detection limit" were calculated for the selected prominent lines with the exist of the four matrix elements. The obtained information is useful in the selection of the best analytical lines for the determination of REEs in the other REEs' matrices.