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The extremal problem of two types of high order spectra for graphs are considered, which are called r -adjacency spectrum and t -clique spectrum, respectively. In this paper, we obtain the maximum r -adjacency spectral radius of a K r + 1 minor-free graph of order n in the case 1 ≤ r ≤ 3 , which implies the Hadwiger's conjecture is true for 1 ≤ r ≤ 3. Moreover, an upper bound of the 3-clique spectral radius of a B k -free and K 2 , l -free graph G of order n is given, where B k is the graph consisting of k triangles sharing an edge. As a corollary of this result, we obtain an upper bound of the number of the triangles for G which improves a result of Alon and Shikhelman (2016). [ABSTRACT FROM AUTHOR]

Although convolutional neural networks (CNNs) have achieved remarkable progress in weakly supervised semantic segmentation (WSSS), there are still deficiencies of object incompleteness due to the lack of receptive field and insufficient utilization of global context information of CNN. Based on the above observations, we propose a simple and effective method, WegFormer. Specifically, WegFormer captures the global context information with the Vision Transformer (ViT) as the classification network and is equipped with Deep Taylor Decomposition (DTD) principle and Soft Erase (SE) module to generate more integral pseudo labels and smooth further. However, we observe that although the generated pseudo‐labels are more complete, they intrude into the background region, that is, background incompleteness problem. The Efficient Potential Object Mining (EPOM) module we propose solves this problem well. Extensive experiments on the challenging PASCAL VOC 2012 and MS COCO 2014 demonstrate the effectiveness of WegFormer, where superior results of 71.4% and 38.3% are obtained on the PASCAL VOC 2012 and MS COCO 2014 validation sets, respectively. [ABSTRACT FROM AUTHOR]

The initial seed based on the convolutional neural network (CNN) for weakly supervised semantic segmentation always highlights the most discriminative regions but fails to identify the global target information. Methods based on transformers have been proposed successively benefiting from the advantage of capturing long-range feature representations. However, we observe a flaw regardless of the gifts based on the transformer. Given a class, the initial seeds generated based on the transformer may invade regions belonging to other classes. Inspired by the mentioned issues, we devise a simple yet effective method with multi-estimations complementary patch (MECP) strategy and adaptive conflict module (ACM), dubbed MECPformer. Given an image, we manipulate it with the MECP strategy at different epochs, and the network mines and deeply fuses the semantic information at different levels. In addition, ACM adaptively removes conflicting pixels and exploits the network self-training capability to mine potential target information. Without bells and whistles, our MECPformer has reached new state-of-the-art 72.0 % mIoU on the PASCAL VOC 2012 and 42.4 % on MS COCO 2014 dataset. The code is available at https://github.com/ChunmengLiu1/MECPformer. [ABSTRACT FROM AUTHOR]

The physical and chemical properties of nanoribbon edges are important for characterizing nanoribbons and applying them in electronic devices, sensors, and catalysts. The mechanical response of molybdenum disulfide nanoribbons, which is an important issue for their application in thin resonators, is expected to be affected by the edge structure, albeit this result is not yet being reported. In this work, the width‐dependent Young's modulus is precisely measured in single‐layer molybdenum disulfide nanoribbons with armchair edges using the developed nanomechanical measurement based on a transmission electron microscope. The Young's modulus remains constant at ≈166 GPa above 3 nm width, but is inversely proportional to the width below 3 nm, suggesting a higher bond stiffness for the armchair edges. Supporting the experimental results, the density functional theory calculations show that buckling causes electron transfer from the Mo atoms at the edges to the S atoms on both sides to increase the Coulomb attraction. [ABSTRACT FROM AUTHOR]

D. Cvetković, M. Doob and H. Sachs considered the high order eigenvalue problems of graphs. The high order eigenvalues of a graph G are solutions of the high degree homogeneous polynomial equations derived from G. We propose the adjacency tensor A (G) of a graph G and show that the high order eigenvalues of G can be regarded as eigenvalues of A (G). Some results of the spectrum of the adjacency matrix are extended to the spectrum of A (G) by using the spectral theory of nonnegative tensors. An upper bound of chromatic number is given via the spectral radius of A (G). Our upper bound is a generalization of Wilf's bound χ (G) ≤ ρ (G) + 1 (where ρ (G) is the spectral radius of the adjacency matrix of a graph G) and sharper than the bound of Wilf in some classes of graphs. A formula of the number of cliques of fixed size which involve the spectrum of A (G) is obtained. [ABSTRACT FROM AUTHOR]

The complex symbiotic relationship between inflammation, the gut microbiota, and the central nervous system (CNS) has become a pivotal focus of contemporary biomedical research. Inflammation, as a physiological defense mechanism, plays a dual role as both a protective and pathological factor, and is intricately associated with gut microbiota homeostasis, often termed the "second brain." The gut brain axis (GBA) exemplifies this multifaceted interaction, where gut health exerts significantly regulatory effects on CNS functions. Antibacterial therapies represent both promising and challenging strategies for modulating inflammation and gut microbiota composition to confer CNS benefits. However, while such therapies may exert positive modulatory effects on the gut microbiota, they also carry the potential to disrupt microbial equilibrium, potentially exacerbating neurological dysfunction. Recent advances have provided critical insights into the therapeutic implications of antibacterial interventions; nevertheless, the application of these therapies in the context of CNS health warrants a judicious and evidence-based approach. As research progresses, deeper investigation into the microbial–neural interface is essential to fully realize the potential of therapies targeting inflammation and the gut microbiota for CNS health. Future efforts should focus on refining antibacterial interventions to modulate the gut microbiota while minimizing disruption to microbial balance, thereby reducing risks and enhancing efficacy in CNS-related conditions. In conclusion, despite challenges, a more comprehensive understanding of the GBA, along with precise modulation through targeted antibacterial therapies, offers significant promise for advancing CNS disorder treatment. Continued research in this area will lead to innovative interventions and improved patient outcomes. [Display omitted] • This review explores the intricate relationship between gut microbiota and CNS health. • The dual role of antibacterial therapies in infection control and neuroinflammation modulation is analyzed. • Key insights into the impact of gut microbiota on neurodegenerative diseases are presented. • The article examines the risks and benefits of antibiotics on CNS functions and gut microbiota balance. • Future therapeutic strategies leveraging the gut-brain axis for CNS disorder treatment are discussed. [ABSTRACT FROM AUTHOR]

Generating initial seeds is an important step in weakly supervised semantic segmentation (WSSS). Our approach concentrates on generating and refining initial seeds. The convolutional neural networks (CNNs)–based initial seeds focus only on the most discriminative regions and lack global information about the target. The Vision Transformer (ViT)–based approach can capture long-range feature dependencies due to the unique advantage of the self-attention mechanism. Still, we find that it suffers from distractor object leakage and background leakage problems. Based on these observations, we propose PCSformer, which improves the model's ability to extract features through a Pair-wise Cross-scale (PC) strategy and solves the problem of distractor object leakage by further extracting potential target features through Sub-Prototypes (SP) mining. In addition, the proposed Conflict Self-Elimination (CSE) module further alleviates the background leakage problem. We validate our approach on the widely adopted Pascal VOC 2012 and MS COCO 2014, and extensive experiments demonstrate our superior performance. Furthermore, our method proves to be competitive for WSSS in medical images and challenging scenarios involving deformable and cluttered scenes. Additionally, we extend the PCSformer to weakly supervised object localization tasks, further highlighting its scalability and versatility. The code is available at https://github.com/ChunmengLiu1/PCSformer. [ABSTRACT FROM AUTHOR]

Graphene nanoribbon is an attractive material for nano-electronic devices, as their electrical transport performance can be controlled by their edge structures. However, in most cases, the electrical transport has been investigated only for graphene nanoribbons fabricated on a substrate, which hinders the appearance of intrinsic electrical transport due to screening effects. In this study, we developed special devices based on silicon chips for transmission electron microscopy to observe a monolayer graphene nanoribbon suspended between two gold electrodes. Moreover, with the development of an in-situ transmission electron microscopy holder, the current–voltage characteristics were achieved simultaneously with observing and modifying the structure. We found that the current–voltage characteristics differed between 1.5 nm-wide graphene nanoribbons with armchair and zigzag edge structures. The energy gap of the zigzag edge was more than two-fold larger than that of the armchair edge and exhibited an abrupt jump above a critical bias voltage in the differential conductance curve. Thus, our in-situ transmission electron microscopy method is promising for elucidating the structural dependence of electrical conduction in two-dimensional materials. [ABSTRACT FROM AUTHOR]

The structure-dependent electronic properties of suspended graphene nanoribbon (GNR) have still been important issues. However, these properties have been rarely investigated experimentally due to technical difficulties to produce high-quality suspended GNRs and the identification of atomic structures. Here, we report the electronic properties of suspended GNRs by in situ transmission electron microscopy observations to simultaneously obtain the structural information while measuring the current-voltage (I-V) curves. The suspended GNRs could be obtained by convergent electron beam nanosculpting after careful cleaning by current annealing. The I-V curves were measured for GNRs with a mixture of both zigzag and armchair edges (MGNR) with widths of 3.7 to 1.9 nm and also zigzag edge GNRs (ZGNR) with widths of 1.7 to 1.2 nm. The I-V curves for the ZGNRs were different from those of the MGNRs, as follows. (1) The ZGNRs showed a sharp increase at the threshold voltage in differential conductance-voltage curves. (2) The band gaps measured for ZGNRs were smaller than the band gaps calculated using the GW approximation. (3) The threshold voltage increased with the GNR length. These findings support magnetic-insulator and nonmagnetic-metal nonequilibrium phase transitions as theoretically predicted. Narrow and short ZGNR represents the potential for further nanosized switching devices. Image 1 [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • Eu2+ ions occupy Ba2+, Ca2+(1) and Ca2+(2) sites in Ca 6 BaP 4 O 17 compound. • The energy transfer from E u B a 2 + to E u C a 2 + is mainly due to dipole-dipole interaction. • The energy migration between donors E u B a 2 + is weak even in high doping range. • The emission color is tunable at different doping concentrations and temperatures. • Ca 6 BaP 4 O 17 : Eu2+ materials have potential optical thermometric applications. Abstract Single Eu2+ doped Ca 6 BaP 4 O 17 materials are demonstrated to show potential optical thermometric applications with doping concentration-dependent luminescence and temperature-sensitive luminescence. Eu2+ ions occupy three types of lattice sites based on the results of Rietveld refinements, VUV–UV–vis (vacuum ultraviolet – ultraviolet – visible) luminescence spectra and time-resolved emission spectra. Due to site occupation and energy transfer, the emission color of Eu2+ doped Ca 6 BaP 4 O 17 materials is tunable with the variation of the doping concentration of Eu2+. Then the energy transfer mechanism is analyzed using Inokuti-Hirayama, Yokota-Tanimoto, and Burshteĭn models, respectively. Because of the different thermal behaviors of Eu2+ luminescence in Ba2+, Ca2+(1) and Ca2+(2) sites, Ca 6 BaP 4 O 17 : Eu2+ phosphors appear obvious emission intensity evolutions with the increase of temperature, accompanying with the change of emission color under excitation at 300 and 400 nm, respectively. It indicates that Eu2+ doped Ca 6 BaP 4 O 17 phosphors possess temperature sensitive luminescence characteristics. The temperature-dependent ratiometric emission intensity and the temperature recycle measurements verify the possibility of optical thermometric applications of Ca 6 BaP 4 O 17 : Eu2+ phosphors. [ABSTRACT FROM AUTHOR]

A series of Ce 3+ doped and Ce 3+ -Eu 2+ co-doped Ba 2 MgSi 2 O 7 phosphors was prepared via a high-temperature solid-state reaction technique. The photoluminescence properties, which include synchrotron radiation VUV-UV excitation spectra, emission spectra and concentration effect, thermal stability of Ce 3+ are investigated. Hence the energies of the crystal field split 5d excited states of Ce 3+ are determined. Due to spectral overlap, the energy transfer from sensitizer Ce 3+ to activator Eu 2+ in Ba 2 MgSi 2 O 7 :Ce 3+ , Eu 2+ occurs, and the mechanism is demonstrated to be an electric dipole−dipole interaction. [ABSTRACT FROM AUTHOR]

A series of Ba 2-x Eu x MgSi 2 O 7 phosphors was prepared by a solid-state reaction method at high temperature. The theoretical density of the optimal Ba 1.93 Eu 0.07 MgSi 2 O 7 material was calculated from the Rietveld refinement result. Eu L 3 -edge X-ray absorption near edge structure (XANES) spectrum was measured to confirm the valence of Eu ions in Ba 2 MgSi 2 O 7 . The X-ray excited radioluminescence and the thermoluminescence after β-ray irradiation were investigated based on the VUV-vis photoluminescence. The light yield of the optimal Ba 1.93 Eu 0.07 MgSi 2 O 7 sample under X-ray excitation was estimated to be ~29,000±6000 photons/M eV. So the temperature-dependent luminescence properties of this sample under X-ray and 344 nm excitation were further studied, and the charge traps in the scintillation process were discussed through thermoluminescence spectra. The high scintillation intensity together with an appropriate intrinsic decay time and its non-hygroscopicity endow the further optimized phosphor Ba 1.93 Eu 0.07 MgSi 2 O 7 a promising scintillation material for X-ray detection. [ABSTRACT FROM AUTHOR]

In this work, we first investigatethe relationship between temperatureand lattice parameters by means of Rietveld refinement and then demonstrateits impact on the luminescence peak position of Eu2+inSr8(Si4O12)Cl8. It isfound that with increases in temperature, lattice expansion takesplace without significant distortion of the coordination around Eu2+. As a result, the crystal field splitting of the Eu2+5d state decreases. At the same time, with the experimentaldata of the full width at half-maximum of Eu2+emissionat different temperatures and the infrared spectrum, the effectivephonon frequency is evaluated and the main vibration motions are determinedusing first-principles calculation. Due to the high light yield underX-ray excitation and the excellent thermal stability of luminescenceintensity and decay, a further optimized sample Sr7.7Eu0.3(Si4O12)Cl8could be apotential scintillation material. [ABSTRACT FROM AUTHOR]

Abstract: The lithium-containing lanthanum-oxycarbonate-like borate, Li0.6La2O2.25(BO3)0.7, has been synthesized by solid-state reactions and was found to be isostructural with the type II lanthanum-oxycarbonate La2O2(CO3). The new compound, lithium-containing lanthanum-oxycarbonate-like borate Li0.6La2O2.25(BO3)0.7 has been synthesized and its structure characterized by the Rietveld method using powder X-ray diffraction data. It crystallizes in space group P63/mmc with lattice parameters of a=b=4.03396(3)Å, c=16.5863(2)Å, V=233.746(4)Å3. The mechanism of the lithium incorporation in the borate is that four Li+ cations replace one (B2O)4+ group, i.e. Li0.6La2O2.25(BO3)0.7 can be described as Li2x La2O1.5+2.5x (BO3)1−x , x=0.3 and the lithium incorporation stabilized the type II borate. The luminescent properties of Li0.6La2O2.25(BO3)0.7 doped with Eu3+ were studied, indicating a potential application in white light emitting diodes (WLEDs). [Copyright &y& Elsevier]

[Display omitted] • We observed gradual cleansing process of GNRs by improving contact resistance. • Suspended GNR was cleaned on atomic scale with the current density of 2–5 × 1012 A/m2. • The temperature for cleaning was calculated to be ∼ 700 K by finite element method. • Cleaned monolayer GNR could withstand the current density of 5.1 × 1012 A/m2. • Cleaned bilayer GNR stood current density up to 1.7 × 1013 A/m2 due to closed edges. Graphene nanoribbons (GNRs) are expected in nanodevices and sensors but are degraded by contaminants that adsorb firmly on the surface during the transfer and lithography processes. Current annealing appears to be the most appropriate cleaning method, but its effects have not been quantitatively clarified. To this end, the cleaning processes of suspended monolayer GNRs were observed by in situ transmission electron microscopy. The gradual cleaning processes, which were successfully observed by improving the contact resistance at graphene-metal interface, showed that the GNRs was cleaned on the atomic scale in the current density range of 2.0–5.0 × 1012 A/m2. The corresponding temperature was estimated to be ∼ 700 K by finite element method. To be surprised, clean monolayer and bilayer GNRs withstood current densities of 5.1 × 1012 A/m2 and 1.7 × 1013 A/m2 (current-carrying capacities), respectively, which values were approximately three orders of magnitude higher than those of typical metals. The higher current-carrying capacity of bilayer GNR can be attributed to the formation of closed edges. This study shows that the electrical current is effective for cleaning GNR and boosting the current-carrying capacity. [ABSTRACT FROM AUTHOR]

Abstract: To improve the infrared emission of Yb3+ ions doped in the garnet host Y3Al5O12 (YAG) single crystal through the energy transfer from Ce3+ to Yb3+ ions, the 〈111〉-oriented YAG:Ce3+, YAG:Yb3+, YAG:(Ce3+, Yb3+) and Yb3Al5O12:Ce3+ (YbAG:Ce3+) single crystals were grown using the Czochralski Method, respectively. The excitation and emission spectra of these garnet single crystals were characterized. In YAG:Ce3+ crystal, the yellow emission of Ce3+ ions present, but it was completely extinguished in YAG:(Ce3+, Yb3+) crystal and YbAG:Ce3+ crystal. However, the characteristic absorption bands of Ce3+ still existed in the excitation spectrum of Yb3+ ions, which showed that the energy absorbed by Ce3+ ions can be transferred to Yb3+ ions for its infrared emission. [Copyright &y& Elsevier]

The first bis(imino)carbazolate pincer ligand supported mononuclear Ga(I) compound LGa: (3) was synthesized and fully characterized. Oxidation of 3 with elemental selenium afforded the dinuclear Ga(III) compound [LGa(μ-Se)]2 (4) bearing two bridging Se atoms. Ligand substitution of Cr(CO)6 with 3 under UV light irradiation afforded the gallylene-chromium complex LGa: → Cr(CO)5 (5). In addition, the attempted synthesis of the aluminium analogue LAl: through reduction of LAlI2 (7) only led to isolation of the dinuclear Al(III) compound (LAlI)2 (8), most probably formed through the C–C coupling of two imino radicals. [ABSTRACT FROM AUTHOR]

Background: Cardiovascular disease (CVD) is a chronic disease with a serious prognosis, and obesity is a risk factor for CVD. Lipid accumulation product index (LAP) is a new indicator of obesity, waist circumference, and triglycerides were included in the formula, but its association with CVD is inconsistent. Therefore, this study researched the effect of LAP levels on CVD. Methods: This prospective cohort study was based on the Kailuan cohort. A total of 95,981 participants who completed the first physical examination in 2006 and had no history of CVD or LAP absence were included. The participants were divided into four groups according to the LAP quartile (Q1 - Q4). Up until December 31, 2022, incidence density was calculated for each group. The hazard ratio (HR) and 95% confidence interval (CI) of CVD in each group were calculated by the Cox proportional hazards model. Results: During a median follow-up period of 15.95 years, 9925 incident CVD events occurred (2123 myocardial infarction and 8096 stroke). There were differences in potential confounders among the four groups (P < 0.001). The incidence density and 95% CI of CVD in Q1-Q4 groups were 4.76(4.54, 5.00), 6 0.50(6.24, 6.77), 8.13(7.84, 8.44) and 9.34(9.02, 9.67), respectively. There were significant differences in the survival curves among the four groups by log-rank test (P < 0.001). After adjusting for potential confounders, Cox proportional hazards model results showed that compared with the Q1 group, the HR and 95% CI of CVD in the Q2, Q3, and Q4 groups were1.15(1.08, 1.23), 1.29(1.21, 1.38) and 1.39(1.30, 1.49), respectively. The HR and 95%CI of myocardial infarction were 1.28(1.10, 1.49), 1.71(1.47, 1.98) and 1.92(1.64, 2.23), respectively. The HR and 95%CI of stroke were 1.11 (1.03, 1.19), 1.20 (1.12, 1.29) and 1.28 (1.19, 1.38), respectively. After subgroup analysis by gender, there was no significant interaction (P = 0.169), and the relationship between LAP and CVD in different genders was consistent with the main results. After subgroup analysis by age, there was a significant interaction (P = 0.007), and the association between LAP and CVD in different age groups was consistent with the main results. After subgroup analysis by BMI, there was no significant interaction (P = 0.506), and the association between LAP and CVD in different BMI groups was consistent with the main results. The results remained robust after sensitivity analyses. For each unit increase in ln(LAP), the HR and 95%CI of CVD were 4.07 (3.92, 4.23). Conclusion: This study demonstrated that the risk of CVD increased with the increase of LAP level. The risk of CVD in group Q2 - Q4 was 1.15, 1.29, and 1.39 times higher than that in group Q1, respectively. Clinical trial registration number: ChiCTR2000029767 [ABSTRACT FROM AUTHOR]

We give a Brualdi-type Z-eigenvalue inclusion set of tensors, and prove that it is tighter than the inclusion set given by G. Wang, G. L. Zhou, and L. Caccetta [Discrete Contin. Dyn. Syst. Ser. B, 2017, 22: 187–198] in a special case. We also give an inclusion set for lk,s-singular values of rectangular tensors. [ABSTRACT FROM AUTHOR]

Comprehensive Summary: Müller's hydrocarbon and its analogues are classical examples of Kekulé diradicaloids and have gained great attention. However, because of their high reactivities, their isolation and structural characterizations are still challenging. Herein, we report the isolation of two bis‐BN‐based analogues of Müller's hydrocarbon (1 and 2) as crystalline solids in moderate yields. Experimental results and theoretical studies demonstrated that compound 1 possessing the terminal 1,3,2‐diazaboryl groups is an open‐shell singlet diradicaloid, which is in contrast to the closed‐shell singlet ground states of the bis‐BN‐based analogues of Thiele's and Chichibabin's hydrocarbons with the same terminal groups, illustrating the strong influence of the central linkers on the ground state. Additionally, the replacement of the terminal 1,3,2‐diazaboryl groups in 1 with the bis(2,4,6‐triisopropylphenyl)boryl groups affords 2 with higher diradical character and a smaller singlet‐triplet energy gap. [ABSTRACT FROM AUTHOR]

A series of Ln-doped KSrPO4 (Ln = Ce3+, Eu3+, Eu2+, Pr3+) phosphors are prepared through a high-temperature solid-state method. The KSrPO4 compound is confirmed to possess a β-K2SO4 structure with the Pnma group by Rietveld refinement, and the temperature-dependent lattice parameters are investigated with the powder X-ray diffraction results at different temperatures. Ce3+ and Eu3+ ions are introduced to probe the crystal field strength (CFS) and the lanthanide site symmetry by using VUV-UV-vis spectroscopy. The temperature-dependent luminescence properties of KSrPO4: Ce3+/Eu2+ exhibit an excellent thermal stability of Ce3+/Eu2+ luminescence. Based on the VUV-UV-vis spectra of Ce3+ and Eu3+ doped KSrPO4, the vacuum referred binding energy (VRBE) scheme is constructed to understand the redox properties of Eu, the 5d energy levels of Pr3+ and the thermal quenching characteristics of Ce3+ and Eu2+ luminescence. [ABSTRACT FROM AUTHOR]

The new compound Li0.6La2O2.25(BO3)0.7 and its Eu3+-doped analog are synthesized by solid state reaction of stoichiometric mixtures of H3BO3, Li2CO3, and Ln2O3 (Ln: La, Eu; 1040-1070 °C, 8 h). [ABSTRACT FROM AUTHOR]

Ca3La3(1-x)Ce3x(BO3)5 (x = 0, 0.01, 0.04, 0.10, 0.30, 0.50) phosphors are synthesized by solid state reaction of CaCO3, H3BO3, CeO2, and La2O3 (CO atmosphere, 1100 °C, 10 h). [ABSTRACT FROM AUTHOR]

The heaviest pnictogen-dipyrromethenes DPMPnCl2 (Pn = Sb, 3; Bi 4), which are direct analogues of boron-dipyrromethene (BODIPY), have been readily prepared and isolated as crystalline solids. Both compounds display green photoluminescence with small full widths at half maximum in toluene. Moreover, the reduction of 3 with sodium metal afforded the cyclic dicoordinate stibinidene 5. [ABSTRACT FROM AUTHOR]

Based on the experimentally synthesized dye JZ145 , we designed a series of novel D-A-π-A dyes SPL201-SPL211 with different π-conjugated bridges and a new auxiliary withdrawing group for highly efficient dye-sensitized solar cells (DSSCs) using density functional theory (DFT) and time-dependent DFT(TDDFT). The molecular structures, energy levels, absorption spectra, light-harvesting efficiency (LHE), driving force of injection(ΔG inj ) and regeneration(ΔG reg ) , electron dipole moment (μ normal ) and lifetime of the first excited state(τ) were all scrutinized in details. Results reveal that the additional withdrawing group A2 and the π-conjugated group di-η-hexyl-substituted cyclopentadithiophene (CPDT) are more promising functional groups for the organic dyes with D-A-π-A structure. We further designed SPL212 and SPL213 by employing indoline group as donor, the above screened functional groups as π-conjugated bridge and additional withdrawing group, biscarbodithiolic acid and dicyanovinyl sulfonic acid groups as acceptor group. We found that SPL212 exhibits not only a higher molar extinction coefficient with an increment of 30.8%, larger excited state lifetime and an obvious redshift of 201 nm but also a broader absorption spectrum covering the entire visible range even up to near-IR of 1200 nm compared to JZ145 . So, SPL212 can be used as a promising candidate for DSSCs. In addition, the results also prove that biscarbodithiolic acid may be more favorable than dicyanovinylsulfonic acid as acceptor group in DSSCs. [ABSTRACT FROM AUTHOR]

Tb 3+ activated LaPO 4 nano-phosphors have been prepared by a hydrothermal method. Luminescence spectra in VUV–vis range as well as fluorescence decays were studied for bulk and nano-phosphors. Bulk sample exhibits a relatively fast decay time. The 5 D 3 emissions from Tb 3+ ions increase under X-ray excitation in comparison with that under ultraviolet light excitation. X-ray absorption near-edge structure (XANES) was employed to study the chemical environment and energy transfer efficiency to optical emission. XANES results across different element absorption edges indicate that the chemical environment does not change significantly, only oxygen contributes to luminescence negatively. [ABSTRACT FROM AUTHOR]

A series of Mn 2+ doped Ba 2 MgSi 2 O 7 phosphors with a nominal formula Ba 2 Mg 1− x Mn x Si 2 O 7 ( x = 0.01–0.13) were prepared by a high-temperature solid-state reaction technique. Their VUV–vis photoluminescence spectra, fluorescence decay curves, and low-voltage cathodoluminescence spectra were measured and discussed in detail. The results confirm that the Mn 2+ ions enter into the four-coordinated Mg 2+ site in Ba 2 MgSi 2 O 7 host lattice. The main electron-vibrational interaction (EVI) parameters (such as Huang–Rhys factor, effective phonon energy and position of the zero-phonon line) were evaluated from the experimental spectra. Furthermore, the concentration and the temperature dependence of the emission intensity and the luminescence decays of Ba 2 MgSi 2 O 7 :Mn 2+ were investigated, accordingly the schematic energy levels for Mn 2+ in Ba 2 MgSi 2 O 7 were proposed. Due to the high emission intensity under low-voltage electron beam excitation, a further optimized sample Ba 2 Mg 0.95 Mn 0.05 Si 2 O 7 can be considered as a promising green phosphor for field emission displays (FEDs). [ABSTRACT FROM AUTHOR]

Comprehensive Summary: Both dipyrromethene complexes and radicals of heavier main group elements have been of high interest. However, cationic germanium radicals and dipyrromethene‐based radicals of heavier main group elements are still escaped to be isolated. Herein, we report the isolation and full characterization of a neutral Ge(I)‐masked dipyrromethene‐based radical 3 and the first cationic Ge(III)‐centered radical 5·+ as stable crystalline solids. 3 behaves as a germanium(I) radical in its reaction with diphenyl disulfide to form the Ge—S bond, although X‐ray crystallographic, EPR spectroscopic, computational studies revealed that the unpaired electron of 3 is mainly delocalized over the C9N2Ge backbone and the allylic radical character is also significant in 3. In contrast to 3, the spin density of 5·+ is mainly localized at the Ge center with minor contribution from the dipyrromethene ligand. Moreover, reduction of 5·+ with potassium graphite quantitatively regenerates 5, illustrating a reversible one‐electron redox pair. [ABSTRACT FROM AUTHOR]

The host sensitized near-infrared (NIR) emitting phosphor Sr2CaMoO6:Yb3+ was fabricated by the solid state reaction method. The structural refinement and Raman spectra elucidate that Yb3+ ions preferentially occupy Ca2+ sites. The phosphor can harvest ultraviolet (UV)-blue photons and exhibits intense NIR emission at around 1012 nm with full-width-at-half-maximum of 1635 cm-1. Moreover, the absolute NIR photoluminesence quantum yield (PLQY) is estimated to be about 9%. The Sr2CaMoO6:Yb3+ phosphor may be a promising luminescence downshifting material for improving the spectral response of solar cells in the UV region. (© 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [ABSTRACT FROM AUTHOR]

Two radical cations of bis-BN-based analogues of Thiele's hydrocarbons were facilely synthesized, fully characterized, and theoretically investigated. One-electron oxidation leads to the reduced bond length alternation and NICS values of the central C4N2 rings, suggesting the decreasing antiaromatic character. The spin density of the radical cations is significantly delocalized over the central linkers with a small contribution from two terminal N-heterocyclic boryl units. [ABSTRACT FROM AUTHOR]

An intense reddish-orange phosphor, Gd2MoO6:Sm3+, was developed by solid state chemistry. The photoluminescence excitation and emission spectra, concentration effect are investigated. The results show an efficient energy transfer from MoO66- group to Sm3+ occurs and Sm3+ ion emits an intense reddish-orange light with high color purity and an excellent reproduction quality of optical properties. These results demonstrate that Sm3+ ion with low 4f-4f absorption efficiency in near ultraviolet region can play a role of activator in narrow reddish-orange emitting phosphor potentially useful in ∼370 nm GaN-based light emitting diode through efficient energy feeding by charge transfer absorption of MoO66- group. [ABSTRACT FROM AUTHOR]

Ce 3+ , Pr 3+ singly doped and Ce 3+ –Pr 3+ doubly doped LaBSiO 5 phosphors were prepared by a high-temperature solid state reaction route. The synchrotron radiation VUV–UV excitation spectra of Ce 3+ and Pr 3+ were measured and the luminescence properties were discussed. The band gap of host compound LaBSiO 5 was estimated from the VUV excitation spectrum of sample activated with Gd 3+ . Furthermore, the influence of temperature on luminescence of Ce 3+ was discussed and the activation energy for thermal quenching was evaluated. The occurrence of energy transfer from excited 5d states of Pr 3+ to Ce 3+ was confirmed by the emission spectra of co-doped samples La 0.99− x Pr x Ce 0.01 BSiO 5 and La 0.995− x Pr 0.005 Ce x BSiO 5 with different x values. [ABSTRACT FROM AUTHOR]

• Cubic and square antiprism sublattice transformation of rare-earth clusters. • Coupling of electrostatic and hybridization induced strain controlled the clusters. • Promising approach for up and down-conversion photoluminescence tuning. The clustering of trivalent lanthanide-doped fluorite was divided into four stages. Characters of the first three stage discrete clusters were studied by the density functional theory (DFT) based first principles calculation in the work. The results revealed the relative stabilities of first stage C 4v and C 3v were intimately correlated with that of the second and third stage clusters. The more stable C 4v with interstitial F i − at the nearest site would stabilize the second cubic sublattice centers and C 3v with F i − at next nearest site for the third square antiprism clusters. The lattice mismatch and projected density of states (pDOS) results indicated that coupling of electrostatic, strain, bonding and hybridization among F i −, RE3+ and surrounded lattice anions controlled the site occupation and the correlations. The clusters and clustering features could be modulated and utilized to tune up- and down-conversion photoluminescence for designing of new lanthanide-doped fluorite materials. [ABSTRACT FROM AUTHOR]