Tunable concentration-dependent upconversion and downconversion luminescence in NaYF4: Yb3+, Er3+@ NaYF4: Yb3+, Nd3+ core-shell nanocrystals for a dual-mode anti-counterfeiting imaging application.

Lanthanide-doped luminescent nanocrystals display both upconversion luminescence (UCL) and downconversion luminescence (DCL) properties, which offer potential applications in the second near-infrared window (NIR-II) images and biology sensors. Both UCL and DCL are sensitive to concentrations of activators. However, few works reveal the mechanism of concentration-dependent UCL and DCL. Herein, we synthesize core-shell upconversion nanocrystals (UCNCs) NaYF4: Yb3+(20%), Er3+ (2%)@NaYF4: Yb3+ (x%), Nd3+ (y%) with varying concentration of Nd and Yb ions. The UCL and DCL spectra are recorded under excitation of 980 nm and 808 nm lasers. The results indicate that the luminescence of core-shell UCNCs is influenced by the non-radiative rate between activators (Yb3+ and Nd3+) and the back energy transfer rate from Er3+ ions to activators. UCL tends to be obtained at a relatively low concentration of Yb3+ and Nd3+ ions (about 5%), whereas NIR emission tends to be obtained at a relatively high concentration of Yb3+ and Nd3+ ions (not higher than 20%). Dual-mode anti-counterfeiting imaging is successfully fabricated using core-shell UCNCs, which can be detected and distinguished by visible and infrared detectors. The visible versus infrared brightness of dual-mode anti-counterfeiting imaging can be tuned by varying the concentration of activators (Yb3+, Nd3+). Our work demonstrates concentration-dependent UCL and DCL in core-shell UCNCs, which provides reference to obtain NIR emission in the NIR-II region and adds encrypted dimensions for anti-counterfeiting patterns in the field of file encryption.

Early acute fat embolism syndrome caused by femoral fracture: A case report.

BACKGROUND: Fat embolism syndrome (FES) is a rare complication caused by the presence of fat particles in the microcirculation, which usually occurs within 12-72 h after trauma. At present, there have been few cases of fat embolism presenting within 3 h after trauma. Here, we report a case of femoral fracture complicated with an acute fat embolism caused by a car accident. CASE SUMMARY: A 29-year-old woman with pain, swelling and limited movement of her left lower limb after a car accident was taken by ambulance to our hospital. X-ray examination showed fracture of the middle and lower part of the left femur and fracture of the base of the left fifth metatarsal bone. She was hospitalized and admitted to the orthopedic ward. After the attending doctor performed tibial tubercle bone traction, the patient became confused, followed by respiratory distress. Finally, she was transferred to the intensive care unit. After nearly a month of treatment in the intensive care unit, the patient's cognitive function gradually recovered over 6 mo. CONCLUSION: For patients with early traumatic fractures, young emergency physicians and orthopedics should be aware of the possibility of FES.

Multi-wavelength pumped upconversion enhancement induced by Cu2-xS plasmonic nanoparticles in NaYF4@Cu2-xS core-shell structure.

Cu2-xS nanoparticles (NPs) demonstrate unique tunable localized surface plasmon resonance (LSPR) and nonlinear optical properties, which are promising materials for photoelectric and display devices. In this work, we present highly improved upconversion luminescence (UCL) in the NaYF4:Yb3+, Er3+@NaYF4:Yb3+, Nd3+@Cu2-xS core-shell structure. The UCL enhancement is systemically studied under excitation of multi-wavelengths 808, 980, and 1540 nm, due to the broadband nature of Cu2-xS LSPR. Two different mechanisms synergistically contribute to the UCL enhancement, namely, the LSPR effect and two-photon effect, which lead to the extraordinary power dependence of UCL. UCL enhancement as high as 12-fold is achieved in the core-shell upconversion NPs (UCNPs). The core-shell NPs are printed on a paper substrate using a nano-printing technique, displaying different colors irradiated by different near-infrared light, and have potential applications in anti-counterfeiting, encryption, and display fields. These findings provide a method to design and optimize luminescent materials and demonstrate potential applications of plasmonic semiconductors and UCNPs.

Hole transport layer selection toward efficient colloidal PbS quantum dot solar cells.

The effect of energy level alignment between the hole transport layer (HTL) and active layer in PbS quantum dot (QD) solar cells was investigated. Here, a great variation in device performance was observed when employing different hole transporting materials. Devices using HTLs that could not block electrons only show poor device behaviors, while those employing wide band-gap hole transporting materials with shallow lowest unoccupied molecular orbital (LUMO) energies to block electrons exhibit reduced dark currents as well as enhanced device efficiencies. A power conversion efficiency of 4.4% was obtained by utilizing Poly-TPD as the HTL due to the optimized energy level alignment. These improvements were realized by preventing current leakage and consequent counter diode formation. The efficiency can be further improved to 4.9% by inserting EDT-treated PbS QD film (PbS-EDT) hole transporting materials with higher hole mobility as well as suitable energy levels that can increase the collection efficiency.

The disseminated intravascular coagulation score is a novel predictor for portal vein thrombosis in cirrhotic patients with hepatitis B.

BACKGROUND: The development of portal vein thrombosis (PVT) in cirrhotic patients has not been fully elucidated. The disseminated intravascular coagulation (DIC) score, which is based on readily available and relatively inexpensive coagulation parameters, including platelet count, fibrin-related markers, prothrombin time and fibrinogen, has not been reported regarding PVT development in cirrhotic patients to date. We aimed to evaluate the prognostic value of the DIC score in predicting PVT development in cirrhotic patients with hepatitis B. MATERIAL AND METHODS: A total of 109 cirrhotic patients with hepatitis B were included. Clinical data, laboratory tests and imaging were collected from the patients at baseline and every three months after enrollment. All patients were followed until the study endpoint (either occurrence of PVT or 12months after baseline). We measured routine laboratory parameters and conducted imaging examinations in cirrhotic patients and evaluated the prognostic value of the DIC score as a novel predictor for PVT in patients with cirrhosis. We also compared the effectiveness of the DIC score with other common coagulation and hemodynamic parameters. RESULTS: Among the 109 patients, 14 (12.8%) developed PVT. At the study endpoint, significant increases in D-dimer, Child-Pugh score and DIC score (all P<0.001) and significantly reduced portal flow velocity (P<0.001) were noted in the PVT group. Among the selected factors, the DIC score had the largest area under the curve (AUC) (0.845), followed by the Child-Pugh score (0.778), D-dimer (0.732), and portal vein velocity (0.709). CONCLUSION: Among the selected factors, the DIC score showed non-significantly higher diagnostic performance in predicting the PVT development in cirrhotic patients compared with other factors. A validation cohort of the study is needed in the near future.

Enhanced rare earth photoluminescence in inverse opal photonic crystals and its application for pH sensing.

Concentration quenching effects of identical rare earth (RE) activator ions and energy transfer (ET) between different RE ions often compromise the photoluminescence (PL) quantum efficiency in RE based luminescence materials. Here, we demonstrate that in NaGd(WO4)2:Tb(3+), Eu(3+) inverse opal photonic crystals (IOPCs), the suppression of the emission line located in the photonic stop band (PSB) and a dramatic increase of the lifetimes of Eu(3+) and Tb(3+) ions are observed. More interestingly, the concentration quenching among Eu(3+) ions and ET from Tb(3+) to Eu(3+) is significantly relieved owing to the periodic empty cavity structure of IOPCs. As a consequence, the luminescent quantum efficiency (QE) of the NaGd(WO4)2:Tb(3+), Eu(3+) IOPCs increases ∼2 times more than that of crushed NaGd(WO4)2:Tb(3+), Eu(3+) powder. In addition, a reusable pH sensor with good linear response (pH 5-10) has been designed based on the high surface-to-volume ratio, high connectivity, and enhanced luminescence of NaGd(WO4)2:Tb(3+), Eu(3+)IOPCs, which could be applied to the dynamical detection of pH value.

Remarkable enhancement of upconversion luminescence on 2-D anodic aluminum oxide photonic crystals.

Lanthanide-doped upconversion nanoparticles (UCNPs) are attracting extensive attention due to their unique physical properties and great application potential. However, the lower luminescence quantum yield/strength is still an obstacle for real application. Local field modulation is a promising method to highly enhance the upconversion luminescence (UCL) of the UCNPs. In this work, a novel kind of two-dimensional photonic crystal (2D-PC), anodic aluminum oxides (AAOs), was explored to improve the UCL of NaYF4:Yb(3+),Er(3+) nanoplates (NPs). An optimum enhancement factor (EF) of 65-fold was obtained for the overall intensity of Er(3+) under 980 nm excitation, and 130-fold for the red emission. Systematic studies indicate that UCL enhancement mainly originates from the enlargement of the excitation field by scattering and reflection of AAO PCs. It should also be highlighted that the modulation of 2D-PC on the UCL of NaYF4:Yb(3+),Er(3+) NPs demonstrates weak size-dependent and thickness-dependent behavior, which is well consistent with the stimulated electromagnetic field distribution by the finite difference time domain (FDTD) method.

Observation of Considerable Upconversion Enhancement Induced by Cu2-xS Plasmon Nanoparticles.

Localized surface plasmon resonances (LSPRs) are achieved in heavily doped semiconductor nanoparticles (NPs) with appreciable free carrier concentrations. In this paper, we present the photonic, electric, and photoelectric properties of plasmonic Cu2-xS NPs/films and the utilization of LSPRs generated from semiconductor NPs as near-infrared antennas to enhance the upconversion luminescence (UCL) of NaYF4:Yb(3+),Er(3+) NPs. Our results suggest that the LSPRs in Cu2-xS NPs originate from ligand-confined carriers and that a heat treatment resulted in the decomposition of ligands and oxidation of Cu2-xS NPs; these effects led to a decrease of the Cu(2+)/Cu(+) ratio, which in turn resulted in the broadening, decrease in intensity, and red-shift of the LSPRs. In the presence of a MoO3 spacer, the UCL intensity of NaYF4:Yb(3+),Er(3+) NPs was substantially improved and exhibited extraordinary power-dependent behavior because of the energy band structure of the Cu2-xS semiconductor. These findings provide insights into the nature of LSPR in semiconductors and their interaction with nearby emitters and highlight the possible application of LSPR in photonic and photoelectric devices.

Plasmon-Enhanced Upconversion Luminescence on Vertically Aligned Gold Nanorod Monolayer Supercrystals.

Upconversion nanophosphor is attracting worldwide interests owing to its unique optical properties and great application potentials. However, it is still a great challenge to effectively improve the efficiency/strength of upconversion nanophosphor. Plasmonic modulation is a promising way to solve this bottleneck. In this work, we present a simple yet versatile concept on magnifying upconversion luminescence of NaYF4:Yb(3+), Er(3+) nanocrystals through local field manipulation of surface plasmon. Gold nanorods were directionally assembled into a vertically aligned monolayer supercrystals over large areas. The FDTD simulation indicates that the electromagnetic field strength |E|(2) can be improved about 113 folds at the hot spots of monolayer supercrystals. After optimization, on the surface of the vertically aligned monolayer supercrystals, the overall upconversion luminescence intensity of NaYF4:Yb(3+), Er(3+) under 980 nm excitation was improved more than 35 fold.

Paper-based upconversion fluorescence resonance energy transfer biosensor for sensitive detection of multiple cancer biomarkers.

A paper-based upconversion fluorescence resonance energy transfer assay device is proposed for sensitive detection of CEA. The device is fabricated on a normal filter paper with simple nano-printing method. Upconversion nanoparticles tagged with specific antibodies are printed to the test zones on the test paper, followed by the introduction of assay antigen. Upconversion fluorescence measurements are directly conducted on the test zones after the antigen-to-antibody reactions. Furthermore, a multi-channel test paper for simultaneous detection of multiple cancer biomarkers was established by the same method and obtained positive results. The device showed high anti-interfere, stability, reproducible and low detection limit (0.89 ng/mL), moreover it is very easy to fabricate and operate, which is a promising prospect for a clinical point-of-care test.

Local Field Modulation Induced Three-Order Upconversion Enhancement: Combining Surface Plasmon Effect and Photonic Crystal Effect.

A 2D surface plasmon photonic crystal (SPPC) is achieved by implanting gold nanorods onto the periodic surface apertures of the poly(methyl methacrylate) (PMMA) opal photonic crystals. On the surface of the SPPC, the overall upconversion luminescence intensity of NaYF4 :Yb(3+) , Er(3+) under 980 nm excitation is improved more than 10(3) fold. The device is easily shifted to a transparent flexible substrate, applied to flexible displays.

Highly Efficient LiYF4:Yb(3+), Er(3+) Upconversion Single Crystal under Solar Cell Spectrum Excitation and Photovoltaic Application.

Luminescent upconversion is a promising way to harvest near-infrared (NIR) sunlight and transforms it into visible light that can be directly absorbed by active materials of solar cells and improve their power conversion efficiency (PCE). However, it is still a great challenge to effectively improve the PCE of solar cells with the assistance of upconversion. In this work, we demonstrate the application of the transparent LiYF4:Yb(3+), Er(3+) single crystal as an independent luminescent upconverter to improve the PCE of perovskite solar cells. The LiYF4:Yb(3+), Er(3+) single crystal is prepared by an improved Bridgman method, and its internal quantum efficiency approached to 5.72% under 6.2 W cm(-2) 980 nm excitation. The power-dependent upconversion luminescence indicated that under the excitation of simulated sunlight the (4)F(9/2)-(4)I(15/2) red emission originally results from the cooperation of a 1540 nm photon and a 980 nm photon. Furthermore, when the single crystal is placed in front of the perovskite solar cells, the PCE is enhanced by 7.9% under the irradiation of simulated sunlight by 7-8 solar constants. This work implies the upconverter not only can serve as proof of principle for improving PCE of solar cells but also is helpful to practical application.

Efficacy and safety of anticoagulation therapy with different doses of enoxaparin for portal vein thrombosis in cirrhotic patients with hepatitis B.

BACKGROUND: Patients with cirrhosis have a high incidence of portal vein thrombosis (PVT), and optimal management of PVT in cirrhotic patients remains unclear. Currently, there is no paper on optimal doses of enoxaparin for the management of PVT with cirrhosis. AIMS: To evaluate the efficacy and safety of anticoagulation therapy with different doses of enoxaparin for PVT in cirrhotic patients with hepatitis B. MATERIALS AND METHODS: Sixty-five patients with hepatitis B-related cirrhosis and acute PVT were treated by different doses of enoxaparin. All the patients were assigned randomly to two groups: one group received enoxaparin 1 mg/kg subcutaneously every 12 h and the other group received enoxaparin 1.5 mg/kg subcutaneously every 24 h. Clinical, biochemical evaluation, Doppler ultrasound, and contrast-enhanced computed tomography were performed during the anticoagulation treatment. RESULTS: Of the 65 patients, 51 patients (78.5%) achieved complete/partial recanalization of PVT after 6 months of anticoagulation therapy. Child-Pugh scores were lower in the 51 patients who achieved complete/partial recanalization than those of the 14 nonresponders (P<0.01). No patients showed variceal bleeding during anticoagulation therapy in the two groups. The rates of nonvariceal bleeding with the use of 1.5 mg/kg every 24 h (23.5%) were higher than those with the use of 1 mg/kg every 12 h (6.4%). CONCLUSION: Anticoagulation therapy with different doses of enoxaparin for PVT in hepatitis B patients with cirrhosis is efficient and safe, and 1 mg/kg enoxaparin subcutaneously every 12 h is a better anticoagulation regimen in the treatment of PVT in cirrhotic patients.

von Willebrand factor as a novel noninvasive predictor of portal hypertension and esophageal varices in hepatitis B patients with cirrhosis.

OBJECTIVE: At present, there is no perfect noninvasive method to assess portal hypertension and esophageal varices. Early predicting esophageal varices can provide evidence for managing cirrhotic patients. We aimed to further investigate von Willebrand factor (vWF) as a noninvasive predictor of portal hypertension, especially of esophageal varices. MATERIAL AND METHODS: A total of 60 hepatitis B patients with cirrhosis and 45 healthy subjects were enrolled in this study. Levels of six markers were examined. All patients underwent hepatic venous pressure gradient (HVPG) and esophagogastroduodenoscopy. We evaluated the performance of six factors for diagnosis of portal hypertension and esophageal varices. The vWF levels in liver tissues were observed by immunohistochemistry. Correlations between the level of vWF in liver tissues and HVPG and between levels of vWF in tissues and plasma were examined. RESULTS: Cutoff values of plasma vWF (1510.5 mU/mL and 1701 mU/mL) showed high positive predictive value (PPV, 90.2% and 87.5%) in predicting clinically significant portal hypertension and severe portal hypertension. Cutoff values of vWF (1414 mU/ml and 1990 mU/mL, PPV 90.3% and 86.3%, respectively) were provided to detect the presence and degree of esophageal varices. Linear correlations were observed between levels of vWF in liver tissues and HVPG (r(2) = 0.552, p < 0.001) and between the level of vWF in liver tissues and in plasma (r(2) = 0.461, p < 0.001). CONCLUSION: The vWF is a noninvasive predictor of portal hypertension and esophageal varices in hepatitis B patients with cirrhosis. Increased levels of vWF in liver tissues may induce the elevated plasma vWF levels, but molecular mechanism is needed for further study.

Plasmonic enhancement of the upconversion fluorescence in YVO4:Yb³âº, Er³âº nanocrystals based on the porous Ag film.

The upconversion luminescence (UCL) enhancement based on the surface plasmonic resonance (SPR) of noble metals is a promising way to improve UCL efficiency. However, it is still a challenge to achieve stable and effective UCL enhancement. Here, we present the preparation of the porous Ag/YVO4:Yb(3+), Er(3+) composite film via a simple double annealing method. It is exciting to observe that a maximum 36-fold ((2)H11/2-(4)I15/2) and 30-fold ((4)S3/2-(4)I15/2) UCL enhancement in the porous Ag/YVO4:Yb(3+), Er(3+) composite film, attributed to the effective coupling between SPR and the excitation light by adjusting the SPR peak to the excitation wavelength, controlling the effective coupling distance and improving the scattering-absorption ratio. Furthermore, the enhancement factor strongly depended on the excitation power and the Er(3+) concentration.

Highly improved upconversion luminescence in NaGd(WO4)2:Yb³âº/Tm³âº inverse opal photonic crystals.

The upconversion luminescence (UCL) of rare earth (RE) ions doped nanomaterials has attracted extensive interest because of its wide and great potential applications. However, the lower UCL efficiency is still an obstacle for real applications. Photonic modulation is a novel way to improve the efficiency of UCL. In this work, NaGd(WO4)2:Yb(3+)/Tm(3+) inverse opal photonic crystals (IOPCs) were fabricated through the polymethylmethacrylate (PMMA) template and the modification of the IOPC structure on the emission spectra and dynamics of Tm(3+) ions was systemically studied. It is interesting to observe that in the IOPCs, the high-order UCL (1)D2-(3)H6/(3)F4 was relatively enhanced. At the same time, the local thermal effect induced by laser irradiation was suppressed. Furthermore, the overall intensity ratio of visible UCL to near-infrared (NIR) down-conversion luminescence (DCL) was 2.8-8 times improved than that of the grinded reference (REF) and independent of the photonic stop band (PSB). The studies on UCL dynamics indicated that the nonradiative transition rate of Tm(3+) was considerably suppressed. The facts above indicated that in the IOPCs the UCL efficiency of Tm(3+) was largely improved due to the periodic macroporous structure.

Upconversion luminescence enhancement of Yb(3+), Nd(3+) sensitized NaYF4 core-shell nanocrystals on Ag grating films.

Here, we report the wavelength-dependent and angle-dependent upconversion luminescence (UCL) enhancement of NaYF4:Yb(3+),Tm(3+)@NaYF4:Yb(3+),Nd(3+) core-shell nanocrystals (NCs) resulting from Ag grating structures, which provides a novel insight for improving UCL.

Self-assembly and modified luminescence properties of NaY(MoO4)2:Tb³âº, Eu³âº inverse opals.

Three-dimensional (3D) inverse opal photonic crystals can not only modulate the emissions of the inserted emitters, they also have the advantage of a large surface to volume ratio, which permits their use in noninvasive fluorescence detection. In this work, novel NaY(MoO4)2:Eu(3+) and NaY(MoO4)2:Tb(3+), Eu(3+) inverse opals were synthesized using a polymethylmethacrylate (PMMA) template by the sol-gel method. It was observed that the photoluminescence (PL) intensity and spontaneous decay rates (SDRs) of the inverse opals were suppressed, in contrast to the corresponding ground reference (REF) samples, due to the modulation of the effective refractive index (n(eff)). The concentration quenching of Eu(3+) and energy transfer from Tb(3+) to Eu(3+) were suppressed, due to the periodic empty cavity structure of the inverse opals.

Efficient energy transfer from inserted CdTe quantum dots to YVO4:Eu³âº inverse opals: a novel strategy to improve and expand visible excitation of rare earth ions.

Rare earth (RE)-based phosphors demonstrate sharp emission lines, long lifetimes and high luminescence quantum yields; thus, they have been employed in various photoelectric devices, such as light-emitting diodes (LEDs) and solar spectral converters. However, their applications are largely confined by their narrow excitation bands and small absorption cross sections of 4f-4f transitions. In this paper, we demonstrate a novel strategy to improve and expand the visible excitation bands of Eu(3+) ions through the interface energy transfer (ET) from CdTe quantum dots (QDs) to YVO4:Eu(3+) inverse opal photonic crystals (IOPCs). The significant effects observed in the CdTe QDs/YVO4:Eu(3+) IOPCs composites were that the excitation of Eu(3+) ions was continuously extended from 450 to 590 nm and that the emission intensity of the (5)D0-(7)FJ transitions was enhanced ∼20-fold, corresponding to the intrinsic (7)F1-(5)D1 excitation at 538 nm. Furthermore, in the IOPC network, the ET efficiency from the QDs to YVO4:Eu(3+) was greatly improved because of the suppression of energy migration among the CdTe QDs, which gave an optimum ET efficiency as high as 47%. Besides, the modulation of photonic stop bands (PSBs) on the radiative transition rates of the QDs and Eu(3+) ions was studied, which showed that the decay lifetime constants for Eu(3+) ions were independent of PSBs, while those of QDs demonstrated a suppression in the PSBs. Their physical nature was explained theoretically.

Ag-SiO2-Er2O3 nanocomposites: highly effective upconversion luminescence at high power excitation and high temperature.

Rare Earth (RE) activated upconversion phosphors (UCPs), have demonstrated significant application potentials in some front fields, including solar energy conversion and bio-application. However, some bottleneck problems should be overcame, such as the lower upconversion efficiency, narrower excitation band, concentration-quenching and temperature-quenching. To solve these problems, the Ag-SiO2-Er2O3 nanocomposites were fabricated, in which the upconversion luminescence (UCL) of Er2O3 was white broadband. Through the interaction of Er2O3 with surface plasmon (SP) of silver nanoparticles (SNPs), the threshold power for generating broadbands was suppressed largely in contrast to the Er2O3 nanoparticles (NPs), while the UCL brightness was enhanced remarkably, ranging from several to 10(4) times, which strongly depended on the power density of excitation light. At excitation power density of 1.50 W/mm(2) of 980 nm light, the UCL intensity of Ag-SiO2-Er2O3 is 40-folds than the well-known NaYF4:Yb(3+),Er(3+) commercial powders. And more, it is also interesting to observe that the composites demonstrate two excitation bands extending of 780-980 nm, highly improved UCL with elevated temperature and excitation power density. The UCL mechanism related to UCL enhancement was carefully studied.