The efficacy of all-trans retinoic acid (ATRA) for the treatment of chronic myeloid leukemia (CML) has been reported to be limited both as single-drug treatment or in combination with other drugs. ...Our previous study demonstrated that sphingosine 1-phosphate attenuated the effects of ATRA on human colon cancer cells by blocking the expression of retinoic acid receptor beta. The aim of the present study was to investigate whether the ATRA-dependent proliferation inhibition of K562 cells was regulated by sphingosine kinases (SphKs). The results of cell proliferation assay and reverse transcription-PCR demonstrated that ATRA may exert synergistic effects with the SphK1 inhibitor SKI 5C or the pan-SphK inhibitor SKI II to inhibit the proliferation of K562 cells and upregulate the expression levels of the ATRA-inducible enzyme cytochrome P450 26A1 (CYP26A1). Knocking down the expression of SphK1 or SphK2 in K562 cells by small interfering RNA enhanced the inhibitory effects of ATRA and induced the expression of CYP26A1. Crude asterosaponins, which abrogated the expression of SphK2, also enhanced the effects of ATRA on K562 cells. In conclusion, the results of the present study demonstrated that SphKs may be involved in the regulation of the sensitivity of CML cells to ATRA.
This letter proposes a differential en/decoding scheme for multiple-input multiple-output (MIMO) communication links with distributed transmit antennas, in which neither the transmitter nor the ...receiver knows channel knowledge. The proposed scheme is based on the layered differential space-time codes we present. Simulation results show that the bit error rate (BER) performance is nonidentical in different channel propagation delay cases. The optimum delay time for two transmit antennas system, for example, is about 0.6T s (where T s denotes symbol period) when the links achieve better performance.
To design nonlinear optical (NLO) materials, we focused on combinations of d10 metal cation (Cd2+)-based chloride and morpholine molecules to form organic–inorganic hybrids. The O of morpholine ...containing lone-pair electrons can be integrated with Cd2+ by a ligand-to-metal charge transfer (LMCT) strategy to build acentric structures benefiting from the second-order Jahn–Teller effect. Introduction of the high-electronegativity chlorine can make polyhedrons of acentric crystals more distorted and conducive to a strong second harmonic generation (SHG) response. Therefore, (Morpholinium)2Cd2Cl6 crystals were constructed and synthesized by a solvent evaporation method. (Morpholinium)2Cd2Cl6 belongs to the orthorhombic P212121 space group and shows a one-dimensional (1D) structure with distorted CdCl6 and CdCl4O2 octahedrons. The short cutoff edge of (Morpholinium)2Cd2Cl6 was determined to be about 230 nm. The SHG response of (Morpholinium)2Cd2Cl6 exhibited an intensity of approximately 0.73 × KDP as estimated by the powder second harmonic generation technique. Furthermore, related theoretical calculations were performed to study the relationship of the band structure, refractive anisotropy, electronic state, and nonlinear optical response. Besides, (Morpholinium)2Cd2Cl6 showed relatively good thermal stability. This work can serve as a guide for the design and synthesis of new large NLO hybrid crystals with d10 transition metals.
Organic–inorganic hybrid Pb-halide perovskites have attracted tremendous interest due to their potential application in photovoltaic and optoelectronic fields. However, the toxicity and poor ...stability of Pb-halide perovskites have become key bottlenecks toward their future commercialization and industrialization. Therefore, in this work, two novel hybrid lead-free perovskite nonlinear optical (NLO) crystals (2-AMP)2BiX7·H2O (X = Cl, Br) with high stability were successfully synthesized. Both the crystals belong to the orthorhombic P212121 space group, displaying a zero-dimensional perovskite structure. The thermal, environmental, and solvent atmospheric stabilities were comprehensively investigated, with high thermal stability up to 170 °C and high environmental and high solvent atmospheric stability observed for (2-AMP)2BiBr7·H2O. First-principles calculations were carried out to study the relationship of the structure and properties. A large birefringence of 0.1368@1064 nm was determined for (2-AMP)2BiBr7·H2O, which was derived from the strong aeolotropic conjugated π-electron distribution of planar 2-aminomethylpyridium. A second-harmonic generation (SHG) effect that was 0.25 and 0.32 times that of KH2PO4 (KDP) was measured for (2-AMP)2BiCl7·H2O and (2-AMP)2BiBr7·H2O, respectively, and the stronger SHG response of bromide was attributed to the larger distortions of {BiBr6} octahedrons. This work may offer new guidance for exploration of low toxicity and high stability of perovskite NLO materials.
In modern society, the investigation of highly efficient photoluminescent bulk materials with excitation-induced tunable multicolor luminescence and multiexciton generation (MEG) is of great ...significance to information security and the application of optoelectronic devices. In this study, two bulk Cu-based halide crystals of (C4H10NO)4Cu2Br5·Br and (C4H10NO)4Cu2I5·I·H2O, respectively, with one-dimensional structures were grown by a solvent evaporation method. Unexpectedly, (C4H10NO)4Cu2I5·I·H2O displayed excitation-induced tunable dual-color luminescence; one band is a brilliant green-yellow emission centered at 547 nm with a high photoluminescence quantum yield (PLQY) of up to 169.67%, and the other is a red emission at 695 nm with a PLQY of 75.76%. Just as importantly, (C4H10NO)4Cu2Br5·Br exhibits a strong broadband green-yellow emission at 561 nm under broad band excitation ranging from 252 to 350 nm, a long PL decay lifetime of 106.9 μs, and an ultrahigh PLQY of 198.22%. These materials represent the first two examples of 1D bulk crystals and Cu(I)-based halides that have a PLQY exceeding 100%. Combining the unusual luminescence characteristics with theoretical calculations reveals that MEG contributes to the green-yellow emission with ultrahigh PLQY > 100%, and that the red emission can be ascribed to Cu2I53– cluster-centered emission. Additionally, an information encryption method was designed based on the Morse Code. The high luminescence characteristics of LED devices fabricated using the (C4H10NO)4Cu2Br5·Br and (C4H10NO)4Cu2I5·I·H2O crystals appear to lead to promising applications in solid-state lighting. This work extends the catalog of high-performance luminescent materials and also promotes application prospects of low-dimensional copper-based halides in optoelectronics.
Introducing electronegative species into organic constituents was considered to be one effective strategy for adjusting crystal symmetry and designing new nonlinear optical (NLO) materials. By ...substitution of C4 in piperidine (C5H11N) with electronegative oxygen, organic morpholine (C4H9NO) was easily obtained. Therefore, to design NLO crystals, we focused on combinations of stereochemically active lone-pair (SCALP) cation (Pb2+)-based chloride and bromide with morpholine molecules. In this work, two lead halide hybrid perovskite (C4H10NO)PbX3 (X = Cl, Br, abbreviated as MPbCl3 and MPbBr3, respectively) single crystals with moderate nonlinear optical properties were synthesized by a slow evaporation method. The two title crystals belong to orthorhombic space group P212121 with one-dimensional (1D) chainlike perovskite structures. Theoretical calculations revealed that the second harmonic generation (SHG) responses mainly originate from distorted {PbX6} octahedrons of the inorganic framework. Remarkably, moderate phase-matching SHG effects of about 0.70 and 0.81 times KH2PO4, large birefringences of 0.098 and 0.111 at 1064 nm, and large laser damage thresholds (LDTs) of 19.94 and 46.82 MW/cm2 were estimated for MPbCl3 and MPbBr3, respectively. This work provides a novel strategy for new purpose-designed hybrid NLO crystals by adjustment and modulation of chemical modification.
As a wide band gap semiconductor, gallium nitride (GaN) has high breakdown voltage, excellent structural stability and mechanical properties, giving it unique advantages in applications such as high ...frequency, high power, and high temperature. As a result, it has broad application prospects in optoelectronics and microelectronics. However, the lack of high‐quality, large‐size GaN crystal substrates severely limit the improvement of electronic device performance. To solve this problem, liquid phase growth of GaN has attracted much attention because it can produce higher quality GaN crystals compared to traditional vapor phase growth methods. This review introduces two main methods of liquid phase growth of GaN: the flux method and ammonothermal method, as well as their advantages and challenges. It reviews the research history and recent advances of these two methods, including the effects of different solvents and mineralizers on the growth quality and performance of GaN crystals, as well as various technical improvements. This review aims to outline the principles, characteristics, and development trends of liquid phase growth of GaN, to provide more inspiration for future research on liquid phase growth, and to achieve further breakthroughs in its development and commercial application.
The flux and ammonothermal methods are capable of the growth of large size, high quality GaN crystals, which are the main methods of liquid phase growth. The research progress of these two growth methods in terms of chemical additives and growth process is summarised, and their application prospects in industrial production are discussed.
A novel organic-inorganic hybrid crystal, (C5H12NO)H2PO4 (4-(Hpd)H2PO4), has been synthesized by evaporation method under ambient atmosphere. Based on structure analysis, the compound crystalizes in ...the polar space group P21 with the parameters a = 8.6074 (6) Å, b = 6.3134 (4) Å and c = 9.0934 (7) Å. By the hydrogen bonds, 4-(Hpd)+ cation and (H2PO4)- anion were aligned to form an alternatively intercalated three-dimensional framework. Physical properties including thermal performance, linear and nonlinear optical characteristics were identified. On the basis of the results, a high and broad transmittance has been exhibited at the ultraviolet region and the optical band gaps is proved about 3.71 eV for 4-(Hpd)H2PO4 crystal. PL presented an obvious emission peak with the position at 450 nm. SHG response has been demonstrated and the intensity is about 0.15 time that of KDP. In particular, First-principle density functional theory (DFT) calculation was performed to get insight into the correlations between optical properties and electronic structure. The results reveal that the interactions of 4-(Hpd)+ cations and (H2PO4)- anions are associated with the high transmittance and SHG.
•A novel NLO (C5H12NO)H2PO4 crystal has been synthesized by solution evaporation method.•The alternatively intercalated framework is mainly attributed to hydrogen bonds around 4-(Hpd)+ and (H2PO4)- groups.•An obvious SHG effect has been displayed for 4-(Hpd)H2PO4 crystal with high linear transmittance.•Optical performances of 4-(Hpd)H2PO4 are correlated with the interactions of 4-(Hpd)+ and (H2PO4)- groups.
To design nonlinear optical (NLO) materials, we focused on combinations of d
metal cation (Cd
)-based chloride and morpholine molecules to form organic-inorganic hybrids. The O of morpholine ...containing lone-pair electrons can be integrated with Cd
by a ligand-to-metal charge transfer (LMCT) strategy to build acentric structures benefiting from the second-order Jahn-Teller effect. Introduction of the high-electronegativity chlorine can make polyhedrons of acentric crystals more distorted and conducive to a strong second harmonic generation (SHG) response. Therefore, (Morpholinium)
Cd
Cl
crystals were constructed and synthesized by a solvent evaporation method. (Morpholinium)
Cd
Cl
belongs to the orthorhombic
2
2
2
space group and shows a one-dimensional (1D) structure with distorted CdCl
and CdCl
O
octahedrons. The short cutoff edge of (Morpholinium)
Cd
Cl
was determined to be about 230 nm. The SHG response of (Morpholinium)
Cd
Cl
exhibited an intensity of approximately 0.73 × KDP as estimated by the powder second harmonic generation technique. Furthermore, related theoretical calculations were performed to study the relationship of the band structure, refractive anisotropy, electronic state, and nonlinear optical response. Besides, (Morpholinium)
Cd
Cl
showed relatively good thermal stability. This work can serve as a guide for the design and synthesis of new large NLO hybrid crystals with d
transition metals.
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