Amplifying Photon Upconversion in Alloyed Nanoparticles for a Near-Infrared Photodetector.

Photon upconverison has attracted a substantial amount of interest in diverse fields due to its characteristic anti-Stokes emissions. However, obtaining intense emission under low-power laser irradiation has remained a challenge. Here we report a mechanistic design of activator-sensitizer alloyed nanoparticles to achieve bright upconversion under weak infrared irradiation. This design allows a nearest sensitizer-activator separation to facilitate efficient energy transfer that results in remarkably enhanced upconversion (>2 orders of magnitude) under 0.26 W cm-2 irradiation compared to that of the Er sublattice, and the upconversion quantum yield also shows a 20-fold increase. Interestingly, the alloyed nanoparticles exhibit a gradual change in emission color with an increase in Yb3+ content, and moreover, their emission colors can be dynamically controlled by simply modulating the excitation laser power and pulse widths. Such alloyed nanoparticles show great promise for application in a near-infrared photodetector.

Extraordinary Thermal Stability and Sinter Resistance of Sub-2 nm Platinum Nanoparticles Anchored to a Carbon Support by Selenium.

Nanoparticle sintering has long been a major challenge in developing catalytic systems for use at elevated temperatures. Here we report an in situ electron microscopy study of the extraordinary sinter resistance of a catalytic system comprised of sub-2 nm Pt nanoparticles on a Se-decorated carbon support. When heated to 700 °C, the average size of the Pt nanoparticles only increased from 1.6 to 2.2 nm, while the crystal structure, together with the {111} and {100} facets, of the Pt nanoparticles was well retained. Our electron microscopy analyses suggested that the superior resistance against sintering originated from the Pt-Se interaction. Confirmed by energy-dispersive X-ray elemental mapping and electron energy loss spectra, the Se atoms surrounding the Pt nanoparticles could survive the heating. This work not only offers an understanding of the physics behind the thermal behavior of this catalytic material but also sheds light on the future development of sinter-resistant catalytic systems.

Systematic analysis on the mechanism of Zhizi-Bopi decoction against hepatitis B via network pharmacology and molecular docking.

PURPOSE: Zhizi-Bopi decoction (ZZBPD) is a classic herbal formula with wide clinical applications in treating liver diseases including hepatitis B. However, the mechanism needs to be elucidated. METHODS: Chemical components of ZZBPD were identified by ultra-high-performance liquid chromatography coupled with time-of-flight mass spectrometry (UHPLC-TOF-MS). Then we used network pharmacology to identify their potential targets. Network construction, coupled with protein-protein interaction and enrichment analysis was used to identify representative components and core targets. Finally, molecular docking simulation was conducted to further refine the drug-target interaction. RESULTS: One hundred and forty-eight active compounds were identified in ZZBPD, targeting 779 genes/proteins, among which 174 were related to hepatitis B. ZZBPD mainly influences the progression of hepatitis B through the hepatitis B pathway (hsa05161) via core anti-HBV targets (AKT1, PIK3CA, PIK3R1, SRC, TNF, MAPK1, and MAPK3). Enrichment analysis indicated that ZZBPD can also potentially regulate lipid metabolism and enhance cell survival. Molecular docking suggested that the representative active compounds can bind to the core anti-HBV targets with high affinity. CONCLUSION: The potential molecular mechanisms of ZZBPD in hepatitis B treatment were identified using network pharmacology and molecular docking approaches. The results serve as an important basis for the modernization of ZZBPD.

Controlling upconversion in emerging multilayer core-shell nanostructures: from fundamentals to frontier applications.

Lanthanide-based upconversion nanomaterials have recently attracted considerable attention in both fundamental research and various frontier applications owing to their excellent photon upconversion performance and favourable physicochemical properties. In particular, the emergence of multi-layer core-shell (MLCS) nanostructures offers a versatile and powerful tool to realize well-defined matrix compositions and spatial distributions of the dopant on the nanometer length scale. In contrast to the conventional nanomaterials and commonly investigated core-shell nanoparticles, the rational design of MLCS nanostructures allows us to deliberately introduce more functional properties into an upconversion system, thus providing unprecedented opportunities for the precise manipulation of energy transfer channels, the dynamic control of upconversion processes, the fine tuning of switchable emission colours and new functional integration at a single-particle level. In this review, we present a summary and discussion on the key aspects of the recent progress in lanthanide-based MLCS nanoparticles, including the manipulation of emission and lifetime, the switchable multicolour output and the lanthanide ionic interactions on the nanoscale. Benefitting from the multifunctional and versatile luminescence properties, the MLCS nanostructures exhibit great potential in diversities of frontier applications such as three-dimensional display, upconversion laser, optical memory, anti-counterfeiting, thermometry, bioimaging, and therapy. The outlook and challenges as well as perspectives for the research in MLCS nanostructure materials are also provided. This review would be greatly helpful in exploring new structural designs of lanthanide-based materials to further manipulate the upconversion phenomenon and expand their application boundaries.

Activating Ultrahigh Thermoresponsive Upconversion in an Erbium Sublattice for Nanothermometry and Information Security.

Thermal activation of upconversion luminescence in nanocrystals opens up new opportunities in biotechnology and nanophotonics. However, it remains a daunting challenge to achieve a smart control of luminescence behavior in the thermal field with remarkable enhancement and ultrahigh sensitivity. Moreover, the physical picture involved is also debatable. Here we report a novel mechanistic design to realize an ultrasensitive thermally activated upconversion in an erbium sublattice core-shell nanostructure. By enabling a thermosensitive property into the intermediate 4I11/2 level of Er3+ through an energy-migration-mediated surface interaction, the upconverted luminescence was markedly enhanced in the thermal field together with a striking thermochromic feature under 1530 nm irradiation. Importantly, the use of non thermally coupled red and green emissions contributes to the thermal sensitivity up to 5.27% K-1, 3 times higher than that obtained by using conventional thermally coupled green emissions. We further demonstrate that the controllable surface interaction is a general approach to the thermal enhancement of upconversion for a series of lanthanide-based nanomaterials. Our findings pave a new way for the development of smart luminescent materials toward emerging applications such as noncontact nanothermometry, information security, and anticounterfeiting.

Unimolecular Nano-contrast Agent with Ultrahigh Relaxivity and Very Long Retention for Magnetic Resonance Lymphography.

Magnetic resonance (MR) imaging is very important for noninvasive lymphography. However, the present MR contrast agents still cannot supply strong enough tissue contrast and long observation window. To improve the performance of contrast agents, we introduce one-dimensional unimolecular nanoparticles with a confined and compact poly(acrylic acid) core as nanoparticulate chelates of gadolinium ions. Thus, obtained nanoparticulate T1 contrast agents give r1 relaxivity as high as 136.3 mM-1·s-1 under 3.0 T. By injection at the footpad of mice, the contrast agents provide excellent contrast enhancement of lymphatic drainage and they may arrive at popliteal lymph nodes within 30 min and reside for more than 80 h. High performance of the present contrast agent is attributed to the confined and compact core of materials that increase hydration number, intershell water diffusion, and decrease rotational motion.

[Role of TGF-ß/Smad signaling pathway in diabetic kidney disease and research progress of traditional Chinese medicine intervention].

Diabetic kidney disease is an important microvascular complication of diabetes and the leading cause of end-stage renal disease. Its pathological characteristics mainly include epithelial mesenchymal transition(EMT) in glomerulus, podocyte apoptosis and autophagy, and damage of glomerular filtration barrier. Transforming growth factor-ß(TGF-ß)/Smad signaling pathway is specifically regulated by a variety of mechanisms, and is a classic pathway involved in physiological activities such as apoptosis, proliferation and differentiation. At present, many studies have found that TGF-ß/Smad signaling pathway plays a key role in the pathogenesis of diabetic kidney disease. Traditional Chinese medicine has significant advantages in the treatment of diabetic kidney disease for its multi-component, multi-target and multi-pathway characteristics, and some traditional Chinese medicine extracts, traditional Chinese medicines and traditional Chinese medicine compound prescription improve the renal injury of diabetic kidney disease by regulating TGF-ß/Smad signaling pathway. This study clarified the mechanism of TGF-ß/Smad signaling pathway in diabetic kidney disease by expounding the relationship between the key targets of the pathway and diabetic kidney disease, and summarized the research progress of traditional Chinese medicine in the treatment of diabetic kidney disease by interfering with TGF-ß/Smad signaling pathway in recent years, to provide reference for drug research and clinical treatment of diabetic kidney disease in the future.

Pulse compression of a single-frequency Q-switched fiber laser based on the cascaded four-wave mixing effect.

A pulse compressing technology of single-frequency Q-switched laser based on the cascaded four-wave mixing (CFWM) effect is demonstrated theoretically and experimentally, for the first time to the best of our knowledge. A theoretical model of the pulse compression is established through deconstructing the pulse duration evolution in the high-order Stokes and anti-Stokes lights of CFWM. A pulse compression ratio of (2|m|+1)1/2 is quantificationally obtained with m corresponding to the order number of the CFWM light. Utilizing dual-wavelength (DW) single-frequency Q-switched laser injected into a highly nonlinear fiber (HNLF), the pulse compression and the spectral broadening phenomenon are observed simultaneously. As the order number of the CFWM light increases from 0-order to 3-order, the pulse duration has reduced from 115 ns to 47 ns with a compression ratio of 2.45, which is essentially consistent with the theoretical analysis. The pulse compressing technique by CFWM is conducive to promoting the performance development of the single-frequency Q-switched laser, which can improve the system precision in the Lidar, trace gas detection, and high-precision ranging. Furthermore, this technology based on time-frequency transformation dynamics may be generally applicable to other single-frequency pulsed fiber lasers.

Over-20-octaves-bandwidth ultralow-intensity-noise 1064-nm single-frequency fiber laser based on a comprehensive all-optical technique.

An over-20-octaves-bandwidth ultralow-intensity-noise 1064-nm single-frequency fiber laser (SFFL) is demonstrated based on a comprehensive all-optical technique. With a joint action of booster optical amplifier (BOA) and reflective Yb-doped fiber amplifier (RYDFA), two-fold optical gain saturation effects, respectively occurring in the media of semiconductor and fiber, have been synthetically leveraged. Benefiting from the gain dynamics in complementary time scales, i.e., nanosecond-order carrier lifetime in BOA and millisecond-order upper-level lifetime in RYDFA, the relative intensity noise (RIN) is reduced to -150 dB/Hz from 0.2 kHz to 350 MHz, which exceeds 20-octaves bandwidth. Remarkably, a maximum suppressing ratio of >54 dB is obtained, and the RIN in the range of 0.09-10 GHz reaches -161 dB/Hz which is only 2.3 dB above the shot-noise limit. This broad-bandwidth ultralow-intensity-noise SFFL can serve as an important building block for squeezed light generation, space laser communication, space gravitational wave detection, etc.

All-fiber mode-locked gigahertz femtosecond laser at 1610 nm using a self-developed long-wavelength gain fiber.

We report a compact all-fiber passively mode-locked ultrafast laser with a fundamental repetition rate of 1.6 GHz that uses a self-developed long-wavelength active fiber, i.e., a fluoro-sulfo-phosphate-based Er3+/Yb3+ co-doped fiber (only 6.2 cm in length). This active fiber can provide a net gain coefficient of 0.6 dB/cm at 1610 nm. The high-repetition-rate all-fiber mode-locked laser operates at a low pump power of only approximately 90 mW. The mode-locked pulse train has a period of 625 ps and a 3 dB bandwidth of 7.0 nm, which can support a transform-limited pulse width of 390 fs.

Nanomedicine Directs Neuronal Differentiation of Neural Stem Cells via Silencing Long Noncoding RNA for Stroke Therapy.

Transplantation of neural stem cells (NSCs) is a promising treatment paradigm to replace lost neurons and reconstruct the damaged neural circuit after ischemic stroke. However, most transplanted NSCs often differentiate into astrocytes rather than functional neurons, and the poor neuronal differentiation adversely affects the therapeutic outcome of NSCs and limits their clinical translation for stroke therapy. Herein, a theranostic nanomedicine is developed to codeliver superparamagnetic iron oxide nanoparticles (SPIO) and small interfering RNA/antisense oligonucleotides (siRNA/ASO) against Pnky long noncoding RNA (lncRNA) into NSCs. This nanomedicine not only directs neuronal differentiation of NSCs through silencing the Pnky lncRNA but also allows an in vivo tracking of NSCs with magnetic resonance imaging. The enhanced neuronal differentiation of NSCs significantly improved the structural and functional recovery of the damaged brain after a stroke. The results demonstrate the great potential of the multifunctional nanomedicine targeting lncRNA to enhance stem cell-based therapies for a stroke.

Differentiation between high-grade gliomas and solitary brain metastases: a comparison of five diffusion-weighted MRI models.

BACKGROUND: To compare the diagnostic performance of neurite orientation dispersion and density imaging (NODDI), mean apparent propagator magnetic resonance imaging (MAP-MRI), diffusion kurtosis imaging (DKI), diffusion tensor imaging (DTI) and diffusion-weighted imaging (DWI) in distinguishing high-grade gliomas (HGGs) from solitary brain metastases (SBMs). METHODS: Patients with previously untreated, histopathologically confirmed HGGs (n = 20) or SBMs (n = 21) appearing as a solitary and contrast-enhancing lesion on structural MRI were prospectively recruited to undergo diffusion-weighted MRI. DWI data were obtained using a q-space Cartesian grid sampling procedure and were processed to generate parametric maps by fitting the NODDI, MAP-MRI, DKI, DTI and DWI models. The diffusion metrics of the contrast-enhancing tumor and peritumoral edema were measured. Differences in the diffusion metrics were compared between HGGs and SBMs, followed by receiver operating characteristic (ROC) analysis and the Hanley and McNeill test to determine their diagnostic performances. RESULTS: NODDI-based isotropic volume fraction (Viso) and orientation dispersion index (ODI); MAP-MRI-based mean-squared displacement (MSD) and q-space inverse variance (QIV); DKI-generated radial, mean diffusivity and fractional anisotropy (RDk, MDk and FAk); and DTI-generated radial, mean diffusivity and fractional anisotropy (RD, MD and FA) of the contrast-enhancing tumor were significantly different between HGGs and SBMs (p < 0.05). The best single discriminative parameters of each model were Viso, MSD, RDk and RD for NODDI, MAP-MRI, DKI and DTI, respectively. The AUC of Viso (0.871) was significantly higher than that of MSD (0.736), RDk (0.760) and RD (0.733) (p < 0.05). CONCLUSION: NODDI outperforms MAP-MRI, DKI, DTI and DWI in differentiating between HGGs and SBMs. NODDI-based Viso has the highest performance.

The feasibility of laparoscopic TSME preserving the left colic artery and superior rectal artery for upper rectal cancer.

BACKGROUND: Laparoscopic tumor-specific mesorectal excision (TSME) preserving the left colic artery and superior rectal artery is still a technically challenging procedure. We conducted this study to demonstrate the feasibility of this procedure for upper rectal cancer. METHODS: A total of 184 patients with upper rectal cancer were retrospectively analyzed in our cancer center between April 2010 and April 2017. These patients were treated with either laparoscopic TSME (n = 46) or laparoscopic total mesorectal excision (TME) (n = 138). In the TSME group, the left colonic artery and superior rectal artery were preserved while they were not in the TME group. RESULTS: The operation time in the TSME group was longer than that in the TME group (218.56 ± 35.85 min vs. 201.13 ± 42.65 min, P = 0.004). Furthermore, the number of resected lymph nodes in the TSME group was greater than that in the TME group (19.43 ± 9.46 vs. 18.03 ± 7.43, P = 0.024). The blood loss between the TSME and TME groups was not significant. No mortality occurred in either the TSME or TME groups. One patient in the TME group underwent conversion to laparotomy. The total postoperative complication rates in the TSME and TME groups were 8.7% and 17.4%, respectively. There was no difference in severe complications between the two groups (anastomotic leakage and stenosis). CONCLUSIONS: Laparoscopic TSME preserving the left colic artery and superior rectal artery can be safely conducted for upper rectal cancer.

Dual-Shelled RbLi(Li3 SiO4 )2 :Eu2+ @Al2 O3 @ODTMS Phosphor as a Stable Green Emitter for High-Power LED Backlights.

The stability of luminescent materials is a key factor for the practical application in white light-emitting diodes (LEDs). Poor chemical stability of narrow-band green-emitting RbLi(Li3 SiO4 )2 :Eu2+ (RLSO:Eu2+ ) phosphor hinders their further commercialization even if they have excellent stability against thermal quenching. Herein, we propose an efficient protection scheme by combining the surface coating of amorphous Al2 O3 and hydrophobic modification by octadecyltrimethoxysilane (ODTMS) to construct the moisture-resistant dual-shelled RLSO:Eu2+ @Al2 O3 @ODTMS composite. The growth mechanisms of both the Al2 O3 inorganic layer and the silane organic layer on the phosphor surface are investigated. The results remarkably improve the water-stability of this narrow-band green emitter. The evaluation of the white LED by employing this composite as the green component demonstrates that RLSO:Eu2+ @Al2 O3 @ODTMS is a promising candidate for the high-performance display backlights, and this dual-shelled strategy provides an alternative method to improve the moisture-resistant property of humidity-sensitive phosphors.

Site-Selective Occupancy of Eu2+ Toward Blue-Light-Excited Red Emission in a Rb3 YSi2 O7 :Eu Phosphor.

Establishing an effective design principle in solid-state materials for a blue-light-excited Eu2+ -doped red-emitting oxide-based phosphors remains one of the significant challenges for white light-emitting diodes (WLEDs). Selective occupation of Eu2+ in inorganic polyhedra with small coordination numbers results in broad-band red emission as a result of enhanced crystal-field splitting of 5d levels. Rb3 YSi2 O7 :Eu exhibits a broad emission band at λmax =622 nm under 450 nm excitation, and structural analysis and DFT calculations support the concept that Eu2+ ions preferably occupy RbO6 and YO6 polyhedra and show the characteristic red emission band of Eu2+ . The excellent thermal quenching resistance, high color-rendering index Ra (93), and low CCT (4013 K) of the WLEDs clearly demonstrate that site engineering of rare-earth phosphors is an effective strategy to target tailored optical performance.

[Study on the Photoelectric Performance Indicators of Medical Electronic Endoscope].

OBJECTIVE: To establish a method for measuring the photoelectric performance index (luminance response characteristic and luminance tolerance) of medical electronic endoscope. METHODS: Based on the clinical application and product features of medical electronic endoscope, the umbrella grayscale test chart and the adjustable gray scale test chart are designed and made from two aspects of distribution and density differential. RESULTS: The influence of gray scale arrangement, background illumination intensity and illumination spectrum on photoelectric performance measurement of electronic endoscope is verified by test. CONCLUSIONS: It is a reference for the design analysis, evaluation and modification of electronic endoscope product photoelectric part, whether it is suitable for fast detection of umbels and more accurate gray scale test chart.

Tuning of near-infrared-to-near-infrared luminescence from one-photon to two-photon anti-Stokes shift in Ca3Ga2- xCrxGe3O12 via varying Cr3+ content.

Near-infrared-to-near-infrared (NIR-to-NIR) anti-Stokes luminescence from Cr3+ singly doped Ca3Ga2Ge3O12 (CGGG) occurs under the excitation of an 808 nm diode laser. The anti-Stokes processes vary from one photon to two photon, depending on the Cr3+ content (x) in Ca3Ga2-xCrxGe3O12. The results suggest that phonon-assisted anti-Stokes excitation and cooperative energy transfer are involved in the observed upconversion (UC) processes of CGGG:Cr3+. The relevant Cr3+-doping-concentration-dependent NIR-to-NIR anti-Stokes luminescent mechanism, either one-photon or two-photon UC, is investigated. Such an observation on modulating the UC process via varying the doping concentration is helpful in broadening the understanding of UC phenomena.

Unusual anti-thermal degradation of bismuth NIR luminescence in bismuth doped lithium tantalum silicate laser glasses.

For application of bismuth laser glasses in either fiber amplifier or laser, their performance stability in long run should be understood especially in extreme conditions. However, so far, there are few reports on it. Here, we found, after the cycle experiments on heating and cooling, that the proper increase of lithium content in lithium tantalum silicate laser glass can lead to unusual anti-thermal degradation of bismuth NIR luminescence, which completely differs from the scenario in germanate glass. FTIR, 29Si MAS NMR spectra, absorption and dynamic photoluminescence spectra are employed to unravel how this happens. The results illustrate that it should be due to the decrease of polymerization of silicate glass network, which in turn allows the regeneration at 250°C, and therefore, the content increase of bismuth NIR emission centers. In the meanwhile, we noticed though Bi luminescence can be thermally quenched its peak does not shift along with temperature, which seldom appears in laser materials. The unique property might guarantee the unshift of Bi fiber laser wavelength once such glass was made into fiber devices even as the environmental temperature changes. The role of lithium is discussed in the evolution of glass structures, the suppression of glass heterogeneity, and the thermal stability of Bi luminescence, and it should be helpful to design homogeneous silicate laser glass with outstanding thermal stability.

Constructing Interfacial Energy Transfer for Photon Up- and Down-Conversion from Lanthanides in a Core-Shell Nanostructure.

We report a new mechanistic strategy for controlling and modifying the photon emission of lanthanides in a core-shell nanostructure by using interfacial energy transfer. By taking advantage of this mechanism with Gd(3+) as the energy donor, we have realized efficient up- and down-converted emissions from a series of lanthanide emitters (Eu(3+) , Tb(3+) , Dy(3+) , and Sm(3+) ) in these core-shell nanoparticles, which do not need a migratory host sublattice. Moreover, we have demonstrated that the Gd(3+) -mediated interfacial energy transfer, in contrast to energy migration, is the leading process contributing to the photon emission of lanthanide dopants for the NaGdF4 @NaGdF4 core-shell system. Our finding suggests a new direction for research into better control of energy transfer at the nanometer length scale, which would help to stimulate new concepts for designing and improving photon emission of the lanthanide-based luminescent materials.

Homogeneity of bismuth-distribution in bismuth-doped alkali germanate laser glasses towards superbroad fiber amplifiers.

Compared to rare-earth doped glasses, bismuth-doped glasses hold promise for super-broadband near-infrared (NIR) photoemission and potential applications in optical amplification. However, optically active bismuth centers are extremely sensitive to the properties of the surrounding matrix, and also to processing conditions. This is strongly complicating the exploitation of this class of materials, because functional devices require a very delicate adjustment of the redox state of the bismuth species, and its distribution throughout the bulk of the material. It also largely limits some of the conventional processing routes for glass fiber, which start from gas phase deposition and may require very high processing temperature. Here, we investigate the influence of melting time and alkali addition on bismuth-related NIR photoluminescence from melt-derived germanate glasses. We show that the effect of melting time on bismuth-related absorption and NIR photoemission is primarily through bismuth volatilization. Adding alkali oxides as fluxing agents, the melt viscosity can be lowered to reduce either the glass melting temperature, or the melting time, or both. At the same time, however, alkali addition also leads to increasing mean-field basicity, what may reduce the intensity of bismuth-related NIR emission. Preferentially using Li2O over Na2O or K2O presents the best trade-off between those above factors, because its local effect may be adverse to the generally assumed trend of the negative influence of more basic matrix composition. This observation provides an important guideline for the design of melt-derived Bi-doped glasses with efficient NIR photoemission and high optical homogeneity.