Fabrication of Nd3+ and Yb3+ doped NIR emitting nano fluorescent probe: A candidate for bioimaging applications.

The intentional design of rare earth doped luminescent architecture exhibits unique optical properties and it can be considered as a promising and potential probe for optical imaging applications. Calcium fluoride (CaF2) nanoparticles doped with optimum concentration of Nd3+ and Yb3+ as sensitizer and activator, respectively, were synthesized by wet precipitation method and characterized by x-ray diffraction (XRD) and photoluminescence. In spite of the fact that the energy transfer takes place from Nd3+ to Yb3+, the luminescence intensity was found to be weak due to the lattice defects generated from the doping of trivalent cations (Nd3+ and Yb3+) for divalent host cations (Ca2+). These defect centres were tailored via charge compensation approach by co-doping Na+ ion and by optimizing its concentration and heat treatment duration. CaF2 doped with 5 mol% Nd3+, 3 mol% Yb3+ and 4 mol% Na+ after heat treatment for 2 h exhibited significantly enhanced emission intensity and life time. The ex vivo fluorescence imaging experiment was done at various thickness of chicken breast tissue. The maximum theoretical depth penetration of the NIR light was calculated and the value is 14 mm. The fabricated phosphor can serve as contrast agent for deep tissue near infrared (NIR) light imaging.

NaGdF4:Yb,Er-Ag nanowire hybrid nanocomposite for multifunctional upconversion emission, optical imaging, MRI and CT imaging applications.

The effect of novel silver nanowire encapsulated NaGdF4:Yb,Er hybrid nanocomposite on the upconversion emission and bioimaging properties has been investigated. The upconvension nanomaterials were synthesised by polyol method in the presence of ethylene glycol, PVP and ethylenediamine. The NaGdF4:Yb,Er-Ag hybrid was formed with upconverting NaGdF4:Yb,Er nanoparticles of size ~ 80 nm and silver nanowires of thickness ~ 30 nm. The surface plasmon induced by the silver ion in the NaGdF4:Yb,Er-Ag nanocomposite resulted an intense upconversion green emission at 520 nm and red emission at 660 nm by NIR diode laser excitation at 980 nm wavelength. The UV-Vis-NIR spectral absorption at 440 nm and 980 nm, the intense Raman vibrational modes and the strong upconversion emission results altogether confirm the localised surface plasmon resonance effect of silver ion in the hybrid nanocomposite. MRI study of both NaGdF4:Yb,Er nanoparticle and NaGdF4:Yb,Er-Ag nanocomposite revealed the T1 relaxivities of 22.13 and 10.39 mM-1 s-1, which are larger than the commercial Gd-DOTA contrast agent of 3.08 mM-1 s-1. CT imaging NaGdF4:Yb,Er-Ag and NaGdF4:Yb,Er respectively showed the values of 53.29 HU L/g and 39.51 HU L/g, which are higher than 25.78 HU L/g of the CT contrast agent Iobitridol. The NaGdF4:Yb,Er and NaGdF4:Yb,Er-Ag respectively demonstrated a negative zeta potential of 54 mV and 55 mV, that could be useful for biological application. The in vitro cytotoxicity of the NaGdF4:Yb,Er tested in HeLa and MCF-7 cancer cell line by MTT assay demonstrated a cell viability of 90 and 80 %, respectively. But, the cell viability of NaGdF4:Yb,Er-Ag slightly decreased to 80 and 78%. The confocal microscopy imaging showed that the UCNPs are effectively up-taken inside the nucleolus of the cancer cells, and it might be useful for NIR laser-assisted phototherapy for cancer treatment. Graphical abstract.

Efficient NIR Emission from Nd, Er, and Tm Complexes with Fluorinated Selenolate Ligands.

(DME)2Ln(SeC6F5)3 (Ln = Nd, Er, Tm) can be isolated in high yield by reductive cleavage of the Se-Se bond in (SeC6F5)2 with elemental Ln in DME. All three Ln compounds are isostructural, with 8 coordinate Ln bound to four O from DME, three terminally bound Se(C6F5), and a dative bond from an arene fluoride to a fluorine at the ortho position of one selenolate. Emission measurements indicate that these compounds are bright NIR sources.

Emission enhancement through Nd3+-Yb3+ energy transfer in multifunctional NaGdF4 nanocrystals.

The growing need for biomedical contrast agents has led to the current development of multi-functional materials such as lanthanide-based nanoparticles (NPs). The optical and magnetic properties these nanoparticles (NPs) possess are important to enhance current biomedical imaging techniques. To increase the optical emissions of the nanoparticles, neodymium (Nd3+) and ytterbium (Yb3+) were introduced into a magnetic host of NaGdF4. The energy transfer between Nd3+ and the Yb3+ was then investigated at multiple concentrations to determine the optimal dopant levels. The NaGdF4:Nd3+,Yb3+ nanoparticles were synthesized through a modified solvothermal method, resulting in rectangular structures, with an average side length of 17.87 ± 4.38 nm. A double dopant concentration of 10% Nd3+ and 4% Yb3+ was found to be optimal, increasing the emission intensity by 71.5% when compared to the widely used Nd3+ single dopant. Decay measurements confirm energy transfer from Nd3+ to Yb3+, with a lifetime shortening from Nd3+ 1064 nm emission and a calculated lifetime of 12.72 ms with 98% efficiency. Despite NaGdF4:Nd3+,Yb3+ NPs showing a slight decrease in their magnetic response at the expense of optimizing optical emission, as it is directly dependent on the Gd3+ concentration, a strong paramagnetic behavior was still observed. These results corroborate that NaGdF4:Nd3+,Yb3+ NPs are viable candidates for multimodal imaging.

Stokes emission in GdF3:Nd³âº nanoparticles for bioimaging probes.

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 solvothermal route to size- and phase-controlled highly luminescent NaYF4:Yb,Er up-conversion nanocrystals.

Size-controlled hexagonal- and cubic-phase NaYF4:Yb,Er nanocrystals with bright fluorescent emission were successfully synthesized via a solvothermal approach at a relatively low temperature (< 300 degrees C). A mixture of ethanol and ethylene glycol or pure ethylene glycol was used as a solvent, whereby changing the ethanol concentration. It is found that, besides reaction temperature and time, the reactant concentration is an important factor to control crystal phase. High reactant concentration, high reaction temperature, high concentration of ethanol and long reaction durations are favorable to the formation of brightly emitting hexagonal-phase nanocrystals. The effects of these reaction conditions on the size and the luminescent properties of the as-prepared nanocrystals are discussed. It is found that 30-120 nm hexagonal NaYF4:Yb,Er nanoparticles can be prepared using 0.04 M reactant concentration in 0-60% ethanol solution at 220 degrees C for 24 h.

Near infrared-emitting Er- and Yb-Er- doped CeF3 nanoparticles with no visible upconversion.

In this work, a host which interacts and enhanced energy transfer to the luminescent center such that it facilitates the infrared emission while avoiding undesired emissions was found. An intense emission at approximately 1530 nm with no other visible emissions was observed in Er- and Yb-Er- doped CeF3 nanoparticles upon excitation at approximately 975 nm. The average measured luminescence lifetimes of the approximately 1530 nm emission for heat-treated CeF3:Er and CeF3:Yb,Er nanoparticles was approximately 4.5-6.5 ms, with internal quantum efficiencies up to approximately 52-75%. These nanoparticles offer a vast range of potential applications, which include optical amplifiers, waveguides, laser materials and infrared imaging probes.

Lanthanide compounds with fluorinated aryloxide ligands: near-infrared emission from Nd, Tm, and Er.

Ln(OC(6)F(5))(3) form stable, isolable compounds with 1,2-dimethoxyethane (DME). Monomeric (DME)(2)Ln(OC(6)F(5))(3) (Ln = Nd, Er, Tm) adopt seven coordinate structures with two chelating DME and three terminal phenoxide ligands. Both (py)(4)Er(OC(6)F(5))(3) and (THF)(3)Yb(OC(6)F(5))(3) were also prepared and structurally characterized, with the latter being a mer-octahedral compound with bond lengths that are geometry dependent. Emission experiments on crystalline powders of the Nd(III), Tm(III), and Er(III) DME derivatives show that these compounds are highly emissive near-infrared sources.

Simple sequence repeats in Haemophilus influenzae.

Simple sequence repeat (SSRs) of DNA are subject to high rates of mutation and are important mediators of adaptation in Haemophilus influenzae. Previous studies of the Rd KW20 genome identified the primacy of tetranucleotide SSRs in mediating phase variation (the rapid reversible switching of gene expression) of surface exposed structures such as lipopolysaccharide. The recent sequencing of the genomes of multiple strains of H. influenzae allowed the comparison of the SSRs (repeat units of one to nine nucleotides in length) in detail across four complete H. influenzae genomes and then comparison with a further 12 genomes when they became available. The SSR loci were broadly classified into three groups: (1) those that did not vary; (2) those for which some variation between strains was observed but this could not be linked to variation of gene expression; and (3) those that both varied and were located in regions consistent with mediating phase variable gene expression. Comparative analysis of 988 SSR associated loci confirmed that tetranucleotide repeats were the major mediators of phase variation and extended the repertoire of known tetranucleotide SSR loci by identifying ten previously uncharacterised tetranucleotide SSR loci with the potential to mediate phase variation which were unequally distributed across the H. influenzae pan-genome. Further, analysis of non-tetranucleotide SSR in the 16 strains revealed a number of mononucleotide, dinucleotide, pentanucleotide, heptanucleotide, and octanucleotide SSRs which were consistent with these tracts mediating phase variation. This study substantiates previous findings as to the important role that tetranucleotide SSRs play in H. influenzae biology. Two Brazilian isolates showed the most variation in their complement of SSRs suggesting the possibility of geographic and phenotypic influences on SSR distribution.

Under-reporting of road traffic injuries to the police: results from two data sources in urban India.

OBJECTIVE: To report the magnitude of under-reporting of road traffic injury (RTI) to the police from population-based and hospital-based data in the urban population of Hyderabad, India. METHODS: In a cross-sectional population-based survey, 10 459 participants aged 5-49 years (94.3% participation), selected using three-stage systematic cluster sampling, recalled the reporting of non-fatal RTIs to the police in the preceding 12 months and fatal RTIs in the preceding 3 years. In addition, 781 consecutive RTI cases presenting to the emergency department of five hospitals provided information on RTI reporting to the police. RESULTS: In the population-based study, of those who had non-fatal RTIs and sought outpatient or inpatient services, 2.3% (95% 1.1% to 3.5%) and 17.2% (95% CI 3.5% to 30.9%), respectively, reported the RTI to the police. Of the non-fatal consecutive RTI cases presenting to emergency departments, 24.6% (95% CI 21.3% to 27.8%) reported the RTI to the police. In the population-based study, 77.8% (95% CI 65.1% to 90.5%) of the fatal RTIs were reported to the police, and of the consecutive fatal RTI cases presenting to emergency departments, 98.1% (95% CI 95.5% to 100%) were reported to the police. The major reasons cited for not reporting RTIs to the police were "not necessary to report" and "hit and run case". CONCLUSIONS: As road safety policies are based on police data in India, these studies highlight serious limitations in estimating the true magnitude of RTIs from these data, indicating the need for better methods for such estimation.

Incidence and burden of road traffic injuries in urban India.

BACKGROUND: The scale of road traffic injuries (RTIs) in India is uncertain because of limitations in the availability and reliability of incidence data. OBJECTIVE: To report these data for Hyderabad city in southern India. METHODS: In a cross-sectional population-based survey, 10 459 participants aged 5-49 years (94.3% participation), selected using three-stage systematic cluster sampling, were interviewed. Participants recalled RTIs in the preceding 3 months and RTI-related death and disability in the household in the preceding 3 years. RTI was defined as an injury resulting from a road traffic crash irrespective of the severity. RESULTS: The age/sex-adjusted annual incidence of non-fatal RTI requiring a recovery period of < or =7, 8-29, and > or =30 days was 13% (95% CI 12.6% to 13.4%), 5.8% (95% CI 5.5% to 6.0%), and 1.2% (95% CI 1.1% to 1.4%), respectively. The overall adjusted rate for non-fatal RTI was 20.7% (95% CI 20.0% to 21.3%). The relative risk of RTI requiring a recovery period of >7 days was significantly higher in the third per capita monthly income quartile (1.24 (95% CI 1.12 to 1.37); p<0.05). The incidence of non-fatal RTI was highest in pedestrians, motorized two-wheeled vehicle users, and cyclists: 6.4, 6.3, and 5.1/100 persons/year, respectively. Annual RTI mortality and disability rates were 38.2 (95% CI 17.5 to 58.8) and 35.1 (95% CI 12.4 to 57.7) per 100,000 population, respectively. CONCLUSIONS: There is a high burden of RTI in this urban population. With the recent attention focused on RTI by the Government of India, these findings may assist in planning appropriate initiatives to reduce the RTI burden.

Spectroscopic studies of solvothermally derived LaF3:Nd nanocrystals.

LaF3:Nd (0.5-10.7 mol%) nanocrystals were solvothermally synthesized and their optical properties were studied. Judd-Ofelt parameterization of the absorption spectra gave a radiative decay time of 846 micros for the 4F3/2 excited state to the four emission channels. Measured fluorescence decay curves for 5 different Nd3+ concentrations were fit with double exponential functions. The decrease in fluorescence decay time shows that concentration quenching is appreciable as the Nd3+ concentration increases. The 0.5 mol% Nd3+ concentration shows a decay time of 800 micros and a radiative quantum efficiency of 95%. For all dopant concentrations, heat-treatment (800 degrees C, 2 h) substantially increased the emission intensity by 2 to 3-orders of magnitude. This emission intensity increase is attributed to reduction in hydroxyls and homogenization of the Nd3+ coordination environment through improved crystalline perfection of the LaF3:Nd lattice.

Spectral analysis of Er(3+)-, Er(3+)/Yb(3+)- and Er(3+)/Tm(3+)/Yb(3+)-doped TeO(2)-ZnO-WO(3)-TiO(2)-Na(2)O glasses.

In this paper, we present the spectroscopic properties of Er(3+)-, Er(3+)/Yb(3+)- and Er(3+)/Tm(3+)/Yb(3+)-doped novel tellurite glasses. From the measured absorption spectra, Judd-Ofelt (JO) intensity parameters (Ω(2), Ω(4) and Ω(6)) have been evaluated for the Er(3+)-doped glass. With 980 nm excitation three strong upconversion emission bands centered at 505, 520 and 630 nm were observed for both Er(3+)- and Er(3+)/Yb(3+)-codoped glasses and the characteristic near-infrared emission bands were spectrally centered at 1.535 µm. The near-infrared spectra of Er(3+)- and Er(3+)/Yb(3+)-doped glasses have shown full width at half-maxima (FWHM) around 100 nm and 120 nm for the erbium [Formula: see text] transition, respectively. The measured maximum decay times of the [Formula: see text] transition (at wavelength 1.535 µm) are about 7.24 ms and 7.68 ms for 1.0Er(3+) and 1.0Er(3+)/ 2Yb(3+) (mol%)-codoped glasses, respectively. The maximum stimulated emission cross sections for the [Formula: see text] transition of Er(3+) and Er(3+)/Yb(3+) are 8.64 × 10(-21) and 6.78 × 10(-21) cm(2). From 1Er(3+)/ 1Tm(3+)/ 2Yb(3+) (mol%)-codoped glass, broad near-infrared emission bands centered at 1510 nm ([Formula: see text]) and 1637 nm ([Formula: see text]) with full width at half-maxima (FWHM) around 52 nm and 60 nm, respectively, were observed. These glasses with broad near-infrared emissions should have potential applications in tunable lasers and broadband optical amplification at low-loss telecommunication windows.

Spectral analysis of RE(3+) (RE = Er, Nd, Pr and Ho):GeO(2)-B(2)O(3)-ZnO-LiF glasses.

This paper reports on the absorption, visible and near-infrared luminescence properties of Er(3+), Nd(3+), Pr(3+) and Ho(3+)-doped alkali fluoride zinc boro germanate glasses. The x-ray diffraction (XRD) and differential thermal analysis (DTA) profiles of the host glass have been carried out, to confirm its structure and thermal stability. From the measured absorption spectra, Judd-Ofelt (JO) intensity parameters (Ω(2), Ω(4) and Ω(6)) have been calculated for all the studied ions. For Pr(3+) and Ho(3+)-doped glasses, upconversion emission spectra have also been measured. Decay curves were measured for the visible emissions of Er(3+), Pr(3+) and Ho(3+) ions at 547 nm (Er(3+): green), 604 nm and 641 nm (Pr(3+): orange and red) and 658 nm (Ho(3+): red), respectively. The near-infrared emission spectra of Er(3+)/Yb(3+) and Nd(3+)-doped glasses have shown full width at half maximum (FWHM) around 95 nm (for the [Formula: see text] transition) and 63 nm (for the [Formula: see text] transition), respectively. The measured maximum decay times of [Formula: see text] transition (at wavelength 1.51 µm) are about 5.72 ms and 6.14 ms for 1.0Er(3+) and 1.0Er(3+)/ 2Yb(3+) (mol%)-codoped glasses, respectively. The maximum stimulated emission cross sections for [Formula: see text] transition of Er(3+) and Er(3+)/Yb(3+) are 5.447 × 10(-21) cm(2) and 4.540 × 10(-21) cm(2). These glasses with better thermal stability, bright visible emissions and broad near-infrared emissions should have potential applications in broadly tunable laser sources, interesting optical luminescent materials and broadband optical amplification in low-loss telecommunication windows.

Patterns of road traffic injuries in a vulnerable population in Hyderabad, India.

OBJECTIVE: To describe patterns of road traffic injuries (RTI) in a vulnerable population-pedestrians and users of motorized two-wheeled vehicles (MTVs)-in Hyderabad, India. METHODS: 4019 pedestrians and 4183 MTV drivers provided information on the most recent road traffic crash (RTC) irrespective of the level of injury in the last one year for 17 454 and 17 242 household members, respectively. Crashes in which any household member was involved as a pedestrian or MTV user were analysed. RESULTS: Involvement in an RTC as a pedestrian or MTV user was reported for 1513 (4.4%, 95% CI 4.2 to 4.6%) people in the last one year. In these crashes, the person involved was an MTV user in 1264 (83.5%), aged 21-40 years in 973 (64.3%), and male in 1202 (79.4%). Six (0.4%) people died in RTCs and the cause was collision with a vehicle/person in 1133 (75%) crashes. Among the 1306 people who were injured and survived, 174 (13.3%) were treated as inpatients, 38 (2.9%) could not return fully to routine daily activities, 630 (48.2%) took leave from their regular occupation, and 13 (1%) lost their jobs following injury. Using a three month recall period, the annual incidence per 100 000 population of RTC as a pedestrian or MTV user was 2288 and of non-fatal RTI was 1931, and that of fatal RTI using one year recall period was 17.3 in this population. CONCLUSIONS: These findings on how RTI are caused, their type, and outcomes in pedestrians and MTV users can assist in identifying interventions to improve road safety for this vulnerable population in India, and can also be useful for monitoring the effectiveness of such interventions.

Pneumonia due to Trichosporon beigelii infection in HIV positive patient--a case report.

Pulmonary infection due to Trichosporon beigelii is uncommon. A case of Pneumonia in a 28 year old male patient with positive HIV status, secondary to Trichosporon beigelii is reported.

Has treatment for childhood gastroenteritis changed?

Because so many children with gastroenteritis in our area were being treated with drugs, which are potentially harmful, we assessed the extent of treatment before admission to hospital of 288 children. Sixty four had been treated: 45 with antibiotic, antidiarrhoeal, or antiemetic drugs and 34 had been given glucose-electrolyte solution, 15 of those had also been given drugs; 119 had had no treatment. Since 1979 there has been a decrease in the use of drugs for gastroenteritis, but glucose-electrolyte mixtures are still underused.