Analysis of Influence of Network Structure, Knowledge Stock and Absorptive Capacity on Network Innovation Achievements

AbstractIn the increasingly fierce competition and increasingly volatile environment today, the important position of innovation has been widely accepted by theorists and business enterprise resources. Based on the domestic and foreign relevant research, we discusses the influence of network structure, knowledge stock and absorptive capacity on the network innovation achievements, constructs the theoretical relation model and an empirical analysis by using 124 enterprises of Xi’an high-tech industrial parks as the object, the result of the research indicates that, the network structure and knowledge stock to absorptive capacity have a positive impact on role, and both can also influence innovation performance through absorbing ability, absorptive capacity played a certain role of intermediary; Meanwhile, the network structure and the knowledge accumulation play an directly positive promoting role to the innovation performance

Functional Molecular Magnetic Materials Based on Transition Metal Complexes, Organocyanide Radicals and Metal Organic Frameworks

Molecule-based functional magnetic materials are of great interest due to their promising potential applications in new generation of electronic devices. Single molecule magnets (SMMs) and spin-crossover (SCO) moieties are two important categories of molecular materials that exhibit magnetic bistability. Solid state assemblies of these molecules combined with other functional moieties, such as tetracyanoquinodimethane (TCNQ) and metal organic frameworks (MOFs) can result in an enhancement of the original properties and/or coexistence/synergistic interactions of more than one functionality. The goal of the research in this dissertation was to explore ways to manipulate solid state structures and physical properties of SMMs and SCO building blocks by (1) manipulating supramolecular interactions between TCNQ and SCO/SMM units and (2) using crystalline MOFs platforms for nanostructuring SMMs for potential applications in electronic devices. Two types of molecular magnetic bistability, SMM properties (in [Coᶦᶦ(Fctp)₂](TCNQ)₂ (1)) and SCO (in [Coᶦᶦ(Fctp)₂](TCNQ)₂·MeCN (2) and [Coᶦᶦ(Fctp)₂](TCNQF)₂·MeCN (3)), have been achieved with the same transition metal complex, [Coᶦᶦ(Fctp)₂]²⁺, by using the two TCNQ radicals, TCNQ·⁻ and TCNQF·⁻. Single crystal structures and theoretical computational studies reveal that the supramolecular interactions play important roles in the tuning of the magnetic properties. A mixed-stacked of partially charged TCNQ (electron acceptor) and the phenothiazinyl (PTZ, electron donor) group on the SCO molecule ([Co(PTZ-tpy)₂]²⁺) were achieved in the compound [Co(PTZ-tpy)₂]₂(TCNQ)₄.₅·2.5MeCN (6) by introducing charge transfer interactions between conducting and SCO building blocks. The temperature dependent solid state structures as well as the magnetic and conducting properties were compared to the non-SCO Zn analogues, [Zn(PTZtpy)₂]₂(TCNQ)₄.₅·2.5MeCN (7) which revealed synergistic behavior of SCO and electron transfer between different TCNQ stacks as well as the semiconducting properties. The results demonstrate that introducing supramolecular interactions is a promising way to manipulate solid state structure as well as to realize interesting synergistic effects between different functionalities. Finally, the installation of octahedral Coᶦᶦsingle SMM sites in the mesoporous MOF, UMCM-1, was achieved via post synthetic ion exchange reactions. Detailed studies of magnetization relaxation processes of the installed Coᶦᶦ SMMs moieties were performed. The results indicate that the undesired Raman and direct relaxation processes were suppressed by using the mesoporous MOF as a platform for the SMMs assembly

Formation of a Fast Charge Transfer Channel in Quasi-2D Perovskite Solar Cells through External Electric Field Modulation

Quasi-2D perovskites solar cells exhibit excellent environmental stability, but relatively low photovoltaic properties, compared with 3D perovskites solar cells. However, charge transport and extraction in quasi-2D perovskite solar cells are still limited by the inevitable quantum well effect, resulting in low power conversion efficiency (PCE). To date, most efforts concentrate on crystal orientation and favorable alignment during materials and films processing. In this paper, we demonstrated that the quasi-2D perovskite [(BA)2(MA)3Pb4I13 (n = 4)] solar cells show an optimized device performance through forming a fast charge transfer channel among 2D quantum wells through external electric field modulation, with appropriate modulation bias and time after the device has been fabricated. Essentially, ions will move directionally due to local polarization in quasi-2D perovskite solar cells under the action of electric field modulation. More importantly, the mobile ions function as a dopant to de-passivate the defects when releasing at grain boundaries, while decreasing built-in potential by applying forward modulation bias with proper modulation time. The capacitance-voltage characteristics indicate that electric field modulation can decrease the charge accumulation and improve the charge collection in quasi-2D perovskite solar cells. Photoluminescence (PL) studies confirm that the non-radiative recombination is reduced by electric field modulation, leading to enhanced charge transfer. Our work indicates that external electric field modulation is an effective method to form a fast charge transfer channel among 2D quantum wells, leading to enhanced charge transfer and charge collection through local polarization toward developing high–performance quasi-2D perovskite devices

Structural distortions of the spin-crossover material [Co(pyterpy)2](TCNQ)2 mediated by supramolecular interactions.

The incorporation of TCNQ˙− (7,7,8,8-tetracyanoquinodimethane) radicals as counterions for the spin-crossover material [Co(pyterpy)2](TCNQ)2·solvent (pyterpy = 4′-(4′′′-pyridyl)-2,2′:6′,2′′-terpyridine) leads to structural distortions of the [Co(pyterpy)2]2+ spin-crossover cation as compared to [Co(pyterpy)2](PF6)2. Variable temperature structural and magnetic studies indicate that the supramolecular π-stacking interactions between the terminal pyridyl groups and TCNQ radicals play a crucial role in the spin-crossover properties

Miniature multimodal endoscopic probe based on double-clad fiber

International audienceOptical coherence tomography (OCT) can obtain light scattering properties with a high resolution, while photoacoustic imaging (PAI) is ideal for mapping optical absorbers in biological tissues, and ultrasound (US) could penetrate deeply into tissues and provide elastically structural information. It is attractive and challenging to integrate these three imaging modalities into a miniature probe, through which, both optical absorption and scattering information of tissues as well as deep-tissue structure can be obtained. Here, we present a novel side-view probe integrating PAI, OCT and US imaging based on double-clad fiber which is used as a common optical path for PAI (light delivery) and OCT (light delivery/detection), and a 40 MHz unfocused ultrasound transducer for PAI (photoacoustic detection) and US (ultrasound transmission/receiving) with an overall diameter of 1.0 mm. Experiments were conducted to demonstrate the capabilities of the integrated multimodal imaging probe, which is suitable for endoscopic imaging and intravascular imaging

The solid component within part-solid nodules: 3-dimensional quantification, correlation with the malignant grade of nonmucinous pulmonary adenocarcinomas, and comparisons with 2-dimentional measures and semantic features in low-dose computed tomography

Abstract Background There is no consensus on 3-dimensional (3D) quantification method for solid component within part-solid nodules (PSNs). This study aimed to find the optimal attenuation threshold for the 3D solid component proportion in low-dose computed tomography (LDCT), namely the consolidation/tumor ratio of volume (CTRV), basing on its correlation with the malignant grade of nonmucinous pulmonary adenocarcinomas (PAs) according to the 5th edition of World Health Organization classification. Then we tested the ability of CTRV to predict high-risk nonmucinous PAs in PSNs, and compare its performance with 2-dimensional (2D) measures and semantic features. Methods A total of 313 consecutive patients with 326 PSNs, who underwent LDCT within one month before surgery and were pathologically diagnosed with nonmucinous PAs, were retrospectively enrolled and were divided into training and testing cohorts according to scanners. The CTRV were automatically generated by setting a series of attenuation thresholds from − 400 to 50 HU with an interval of 50 HU. The Spearman’s correlation was used to evaluate the correlation between the malignant grade of nonmucinous PAs and semantic, 2D, and 3D features in the training cohort. The semantic, 2D, and 3D models to predict high-risk nonmucinous PAs were constructed using multivariable logistic regression and validated in the testing cohort. The diagnostic performance of these models was evaluated by the area under curve (AUC) of receiver operating characteristic curve. Results The CTRV at attenuation threshold of -250 HU (CTRV− 250HU) showed the highest correlation coefficient among all attenuation thresholds (r = 0.655, P < 0.001), which was significantly higher than semantic, 2D, and other 3D features (all P < 0.001). The AUCs of CTRV− 250HU to predict high-risk nonmucinous PAs were 0.890 (0.843–0.927) in the training cohort and 0.832 (0.737–0.904) in the testing cohort, which outperformed 2D and semantic models (all P < 0.05). Conclusions The optimal attenuation threshold was − 250 HU for solid component volumetry in LDCT, and the derived CTRV− 250HU might be valuable for the risk stratification and management of PSNs in lung cancer screening

A cobalt(ii) spin-crossover compound with partially charged TCNQ radicals and an anomalous conducting behavior

A spin-crossover conductor with partially charged TCNQ exhibits a high room temperature conductivity and an anomaly in conductivity.</p

Structure and thermodynamics of water adsorption in NU-1500-Cr

Metal-organic frameworks (MOFs) are a class of materials with diverse chemical and structural properties, and have been shown to effectively adsorb various types of guest molecules. The mechanism of water adsorption in NU-1500-Cr, a high-performance atmospheric water harvesting MOF, is investigated using a combination of molecular dynamics simulations and infrared spectroscopy. Calculations of thermodynamic and dynamical properties of water as a function of relative humidity allow for following the adsorption process from the initial hydration stage to complete filling of the MOF pores. Initial hydration begins at the water molecules that saturate the open Cr3+ sites of the framework, which is then followed by the formation of water chains that extend along the channels connecting the hexagonal pores of the framework. Water present in these channels gradually coalesces and fills the hexagonal pores sequentially after the channels are completely hydrated. The development of hydrogen-bond networks inside the MOF pores as a function of relative humidity is characterized at the molecular level using experimental and computational infrared spectroscopy. A detailed analysis of the OH-stretch vibrational band indicates that the low-frequency tail stems from strongly polarized hydrogen-bonded water molecules, suggesting the presence of some structural disorder in the experimental samples. Strategies for designing efficient water harvesting MOFs are also proposed based on the mechanism of water adsorption in NU-1500-Cr

Regenerable Sorbent with a High Capacity for Elemental Mercury Removal and Recycling from the Simulated Flue Gas at a Low Temperature

To remove and recycle elemental mercury from flue gas, a serial of Ce–Mn binary metal oxides was prepared and tested as the regenerable sorbents for mercury capture. Ce_0.5Mn_0.5O_<i>y</i> showed the best performance at 100 °C (about 5.6 mg g^–1 adsorption capacity), and Ce–Mn binary metal oxides could adsorb more elemental mercury than MnO_<i>y</i>. Furthermore, it was found that captured mercury can be released from the sorbent in the form of elemental mercury by heating to 350 °C. Meanwhile, the sorbent can be regenerated and repeatedly used. Powder X-ray diffractometer (PXRD), transmission electron microscopy (TEM), hydrogen temperature-programmed reduction (H₂-TPR), ammonia temperature-programmed desorption (NH₃-TPD), X-ray photoelectron spectroscopy (XPS), and nitrogen adsorption methods were employed to characterize the sorbents. A model based on mercury temperature-programmed desorption (Hg-TPD) data was built to calculate mercury desorption activation energy from the sorbent. Additionally, the impacts of the temperature and flue gas components on the adsorption capacity were investigated. NO had negligible impact on mercury adsorption, while the presence of SO₂ slightly inhibited the capability of sorbents for mercury capture. The results indicated that Ce–Mn binary metal oxides are a promising sorbent for the mercury removal and recycling from flue gas