Lehmanmeier6231

The green, red, near-infrared and near-infrared-to-visible upconverted luminescence properties of Er3+/Yb3+ codoped Y3Ga5O12 nanocrystalline powders have been studied using laser spectroscopy. A diffuse reflectance and luminescence spectra confirm that Er3+ and Yb3+ ions occupy the Y3+ sites of the single-phase cubic nano-garnet. Very bright green and red luminescence of the Er3+ ions are detected by the naked eyes, even for a laser power as low as 15 mW, when the Yb3+ ions are excited at 970 nm. The red upconverted emission is more intense than that under direct excitation of the Er3+ ions. The power dependence and the dynamics of the near-infrared-to-green and near-infrared-to-red upconverted emissions show the existence of different two-photon energy transfer upconversion processes. The results here presented indicate that Er3+/Yb3+ codoped Y3Ga5O12 can be a good candidate as an optical nanoheater and nanothermometer in biomedicine applications in the first biological window.All-inorganic cesium lead halide (CsPbX3, X = Cl, Br, and I) perovskite quantum dots (PQDs) have great potential application due to their unique optoelectronic properties. However, poor luminescence stability caused by some inevitable factors such as light, moisture and heat always restricts their practical application. In this work, the stability of CsPbX3 (X = Cl0.5Br0.5, Br, and Br0.5I0.5) PQDs is improved by encapsulating them in stable hollow mesoporous NaYF4Yb,Tm nanoparticles (HMNPs). Compared to pristine PQDs, HMNP-PQD composites exhibit stable photoluminescence properties that can be maintained for more than 60 days under ambient atmospheric conditions. Thanks to the protection of HMNPs, the composites show much higher long-term stability in highly humid air and enhanced stability against UV light treatment compared to naked CsPbBr3 PQDs. Based on the proposed confinement effects of PQDs coordinated with the hollow mesoporous structure of NaYF4Yb/Tm, the related structural model of NaYF4Yb/Tm@PQD composites is discussed. Moreover, dual-mode luminescence can be observed in the NaYF4Yb/Tm@PQD nanocomposites under 365 nm UV light and 980 nm laser excitation, indicating that the as-designed composites have great potential for dual-mode anti-counterfeiting application. This work provides a new idea for the stabilization and application of CsPbX3 PQDs.Carbosilane ruthenium(ii) dendrimers have been complexed with conventional anti-cancer drugs. Due to its features, the presence of ruthenium within a dendrimer structure improves the anti-cancer properties of nanocomplexes containing 5-flurouracyl, methotrexate and doxorubicin. These dendrimers could be promising carriers of anti-cancer medicines. Ruthenium dendrimers that are positively charged can also enhance the cytotoxicity to cancer cells; moreover, they can form stable complexes with drugs. Results indicate that ruthenium dendrimers combined with doxorubicin and methotrexate significantly reduced the viability of leukaemia 1301 and HL-60 cancer cells.3D N, S, P-doped rice-like C-Zn4Si2O7(OH)2·H2O (C-ZnSi-N2) and rose-like C-Zn2SiO4 (C-ZnSi-CO2) are derived from reed leaves and used for application in supercapacitors. The as-prepared C-ZnSi architectures with a large number of hierarchical pores and high specific surface area from reed leaves have outstanding electrochemical performance. The obtained C-ZnSi-N2 shows 341 F g-1 at the current density of 0.5 A g-1, while the C-ZnSi-CO2 exhibits 498 F g-1, and both of the C-ZnSi materials significantly retain above 99% of their capacitance after 10 000 cycles. Furthermore, the flexible solid-state asymmetric supercapacitors (ASCs) synthesized from C-ZnSi and activated carbon (denoted as C-ZnSi-N2//AC and C-ZnSi-CO2//AC) achieve a high capacitance (405 and 194 mF cm-2 at the current density of 2 mA cm-2, respectively). Besides, the ASC devices show good cycling stability for 7300 cycles with 73% and 77% capacitance retention. The results presented in this study indicate that the N, S, P-doped C-ZnSi architectures from natural reed leaves are promising and efficient materials for manufacturing high performance supercapacitors.Quantum interference dramatically modulates electron transport that provides exciting prospects for molecular electronics. AS101 inhibitor We develop a holistic picture of quantum interference phenomena in molecular conductors based on conjugated hydrocarbons taking into account the interaction of resonances and antiresonances (AR). This interaction can result in the coalescence of resonances and ARs accompanied by a significant quantum transparency change. As such a change results from a small variation of the system parameters, it is essential for reducing power consumption in electronics. We establish that the coalescence of ARs is intimately connected with the exceptional point of an underlying non-Hermitian Hamiltonian. The coalescence of ARs cannot be explained considering only the LUMO and HOMO without orbitals beyond them. Cyclobutadiene is discussed as an example. We show that the interaction of resonances and ARs can also result in the formation of a bound state in the continuum (BIC). Our formalism accounting for separate descriptions of resonances and ARs is especially suitable for describing BICs, which can be considered as either a resonance or an AR with zero width. In particular, we show that benzene in the para-configuration possesses BICs, which can be revealed as narrow Fano resonances (FRs) in the transmission spectrum by perturbing the molecule symmetry. Any BIC can be turned into an FR by a proper change of the system parameters, but the reverse is not true. We demonstrate that BICs are related to such chemical concepts as non-bonding orbitals, radicals, and diradicals. Our analytical results within the Hückel formalism are closely reproduced by ab initio simulations. Therefore, experimentally revealing these phenomena looks quite probable.Changes in the structural dynamics of double stranded (ds)DNA upon ligand binding have been linked to the mechanism of allostery without conformational change, but direct experimental evidence remains elusive. To address this, a combination of steady state infrared (IR) absorption spectroscopy and ultrafast temperature jump IR absorption measurements has been used to quantify the extent of fast (∼100 ns) fluctuations in (ds)DNA·Hoechst 33258 complexes at a range of temperatures. Exploiting the direct link between vibrational band intensities and base stacking shows that the absolute magnitude of the change in absorbance caused by fast structural fluctuations following the temperature jump is only weakly dependent on the starting temperature of the sample. The observed fast dynamics are some two orders of magnitude faster than strand separation and associated with all points along the 10-base pair duplex d(GCATATATCC). Binding the Hoechst 33258 ligand causes a small but consistent reduction in the extent of these fast fluctuations of base pairs located outside of the ligand binding region. These observations point to a ligand-induced reduction in the flexibility of the dsDNA near the binding site, consistent with an estimated allosteric propagation length of 15 Å, about 5 base pairs, which agrees well with both molecular simulation and coarse-grained statistical mechanics models of allostery leading to cooperative ligand binding.Laser-induced breakdown spectroscopy (LIBS) combined with the random forest (RF) algorithm was proposed to predict three pollution indexes (geo-accumulation index, enrichment factor, and potential ecological risk index) of the Cu element in atmospheric sedimentation samples to evaluate the pollution risk. To begin with, the LIBS spectra of 15 atmospheric sedimentation samples from different locations were collected and the copper element was identified using the National Institute of Standards and Technology (NIST) database. Then, the influence of different spectral pretreatment methods (MSC, WT and D1st) on the predictive performance of the RF was discussed according to the calibration set with the determination coefficient (Rc2) and mean relative error (MREC) as evaluation indexes. Next, in order to obtain a better RF calibration model, a variable importance (VI) measurement was applied to select input variables from LIBS spectral data based on the optimal spectral pretreatment method, and the optimal variaout complicated sample preparation to provide a basis for pollution prevention and control measures.3D printing of a stiff and lubricative hydrogel-based meniscus substitute has been challenging since printability and stiffness compromise each other. In this work, based on an upgraded self-thickening and self-strengthening strategy, a unique multiple H-bonding monomer N-acryloylsemicarbazide (NASC) is firstly copolymerized with a super-hydrophilic monomer carboxybetaine acrylamide (CBAA) in dimethyl sulfoxide (DMSO)/H2O to form a soft poly(NASC-co-CBAA) gel, in which PCBAA serves to weaken the H-bonding interaction and avoid hydrophobic phase separation. The poly(NASC-co-CBAA) gel is then loaded with concentrated NASC and CBAA, followed by heating to form a thickening sol ink, which is printed into different objects that are further photoirradiated to initiate the copolymerization of entrapped NASC and CBAA, resulting in the formation of a high performance hydrogel with a Young's modulus of 10.98 MPa, tensile strength of 1.87 MPa and tearing energy of 5333 J m-2 after DMSO is completely replaced with water, due to the re-establishment of NASC H-bonds. Importantly, PCBAA affords high lubricity in printed hydrogels. The printed PNASC-PCBAA meniscus substitute can substitute rabbit's native meniscus and ameliorate the cartilage surface wear within a set 12-week time window, portending great potential as a meniscal substitute and other soft-supporting tissue scaffolds.A novel activity-based Cu2+ fluorescent probe featuring multidentate binding sites was synthesized. It functions through chelation with Cu2+, which in turn specifically triggers hydrolysis of the probe to release a near-infrared emission with AIE + ESIPT properties. The probe was found to be capable of ratiometric imaging of Cu2+ in living HeLa cells.Biphasic calcium phosphate (BCP) granules are osteoconductive biomaterials used in clinics to favor bone reconstruction. Yet, poor cohesivity, injectability and mechanical properties restrain their use as bone fillers. In this study, we incorporated BCP granules into in situ forming silanized hyaluronic acid (Si-HA) and hydroxypropylmethylcellulose (Si-HPMC) hydrogels. Hydrogel composites were shown to be easily injectable (F less then 30 N), with fast hardening properties ( less then 5 min), and similar mechanical properties (E∼ 60 kPa). In vivo, both hydrogels were well tolerated by the host, but showed different biodegradability with Si-HA gels being partially degraded after 21d, while Si-HPMC gels remained stable. Both composites were easily injected into critical size rabbit defects and remained cohesive. After 4 weeks, Si-HPMC/BCP led to poor bone healing due to a lack of degradation. Conversely, Si-HA/BCP composites were fully degraded and beneficially influenced bone regeneration by increasing the space available for bone ingrowth, and by accelerating BCP granules turnover.