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Purpose MicroRNA-936 (miR-936) was previously reported to be dysregulated and involved in the development of non-small cell lung cancer and glioma. However, the functional roles of miR-936 in epithelial ovarian cancer (EOC) remain unclear. In this study, we aimed to evaluate miR-936 expression in EOC and investigate its regulatory role in EOC cell behavior. Methods The expression of miR-936 in EOC was measured by RT-qPCR. Cell proliferation, apoptosis, migration, and invasion in vitro, as well as tumor growth in vivo, were determined by CCK-8, flow cytometry, migration and invasion assays, and xenograft models in nude mice, respectively. Bioinformatics analysis, luciferase reporter assays, RT-qPCR, and Western blot analysis were performed to investigate the relationship between miR-936 and fibroblast growth factor 2 (FGF2). Results miR-936 expression was significantly downregulated in EOC tissues and cell lines. Low miR-936 expression was found to be correlated with the tumor size, FIGO stage, and lymphatic metastasis in EOC patients. Functional experiments indicated that ectopic miR-936 expression suppressed EOC cell proliferation, migration, and invasion; promoted cell apoptosis; and decreased tumor growth in vivo. In addition, the FGF2 gene was verified to be a direct target of miR-936 in EOC cells. FGF2 expression levels were upregulated in EOC tissues and were inversely correlated with miR-936 expression. Furthermore, effects of FGF2 silencing were similar to those of miR-936 overexpression in EOC cells. Recovered FGF2 expression rescued the miR-936-induced inhibitory effects in EOC cells. Notably, miR-936 was able to deactivate the PI3K/Akt signaling pathway in EOC cells by regulating FGF2 both in vitro and in vivo. Conclusion Altogether, our findings provided initial evidence that miR-936 inhibits the aggressiveness of EOC cells in vitro and in vivo, at least partially, by targeting FGF2-mediated suppression of the PI3K/Akt pathway. Therefore, the miR-936/FGF2/PI3K/Akt pathway is a promising therapeutic target for the treatment of EOC patients.

Non-fullerene fused-ring electron acceptors boost the power conversion efficiency of organic solar cells, but they suffer from high synthetic cost and low yield. Here, we show a series of low-cost noncovalently fused-ring electron acceptors, which consist of a ladder-like core locked by noncovalent sulfur–oxygen interactions and flanked by two dicyanoindanone electron-withdrawing groups. Compared with that of similar but unfused acceptor, the presence of ladder-like structure markedly broadens the absorption to the near-infrared region. In addition, the use of intramolecular noncovalent interactions avoids the tedious synthesis of covalently fused-ring structures and markedly lowers the synthetic cost. The optimized solar cells displayed an outstanding efficiency of 13.24%. More importantly, solar cells based on these acceptors demonstrate very low non-radiative energy losses. This research demonstrates that low-cost noncovalently fused-ring electron acceptors are promising to achieve high-efficiency organic solar cells., Recently, the non-fullerene acceptors with fused rings enable high-efficiency organic solar cells but they are not ideal in terms of synthetic cost and yield. Here, Huang et al. report ‘less fused’ acceptors with non-covalent S⋅⋅⋅O interactions and solar cell efficiency of up to 13%.

To develop wide bandgap donor materials for high performance nonfullerene polymer solar cells (NF PSCs), bis(carboxylate) substituted benzo[1,2-b:4,5-b]dithiophene (BDT) weak electron acceptor (A) unit was used to polymerize with 5-alkylthiophene-2-yl-substituted BDT or 5-alkylthiothiophene-2-yl-substituted BDT donor unit to construct donor-acceptor (D-A) alternative polymers PBDT-BDTC and PBDTS-BDTC, respectively. PBDT-BDTC and PBDTS-BDTC exhibit wide bandgaps over 1.90 eV and low lying highest occupied molecular orbital (HOMO) levels below −5.50 eV. The absorption and energy levels of these two polymers match well with those of the typical low bandgap acceptor ITIC-Th, resulting in a good complementary absorption from 300 to 900 nm and a low HOMO level offset of about 0.15 eV. NF PSCs with an inverted device structure were fabricated and power conversion efficiencies (PCEs) higher than 7% were achieve. Furthermore, PBDT-BDTC based PSCs exhibit much better photovoltaic performance than PBDTS-BDTC based ones after the treatment with 0.5% 1,8-diiodooctane (DIO). The optimized devices gave a PCE of 8.32% with an open-circuit voltage (Voc) of 0.92 V, a short-circuit current density (Jsc) of 13.91 mA/cm2, and a fill factor (FF) of 65.21%, indicating that PBDT-BDTC is a promising polymer donor for NF PSCs. To the best of our knowledge, a PCE of 8.32% is the highest record for bis(carboxylate) substituted BDT based polymers.

The expression and clinical significance of stomatin-like protein 2 (SLP-2) in ovarian tumors were investigated. A total of 280 cases of ovarian tissue specimens preserved from inpatients after surgical treatments in the Department of Oncology of Yidu Central Hospital of Weifang from April 2013 to May 2016 were collected, including 130 cases of malignant ovarian tumor tissue specimens (malignant tumor group), 75 cases of benign ovarian tumor tissue specimens (benign tumor group) and 75 cases of normal ovarian tissue specimens from bilateral ovariectomy for unilateral ovarian lesions (control group). Immunohistochemistry was used to detect the expression of SLP-2 protein in the three groups. Reverse transcription-quantitative polymerase chain reaction (RT-qPCR) was utilized to detect the relative expression of SLP-2 mRNA in the three groups, and the relationship between SLP-2 and clinicopathological parameters of the ovarian cancer patients was analyzed. The patients with ovarian cancer were divided into the SLP-2 high-expression group and the SLP-2 low-expression group according to the median of SLP-2 relative expression. The survival of patients was analyzed using the Kaplan-Meier and Cox regression model. The results of immunohistochemistry showed that the positive expression rate of SLP-2 protein in the malignant tumor group was significantly higher than that in the benign tumor and control groups (P

We designed and synthesized three PDI derivatives (PDI-II, PDI-III and PDI-IV). All these acceptor molecules have a central benzene core and the PDI units are linked to the central benzene core by an acetylene spacer. PDI-II is a linear molecule, which bears two flanked PDI units, PDI-III is a c3-symmetrical star-shaped molecule with three peripheral PDI units, and PDI-IV is a star-shaped molecule with four PDI units linked to the 1,2,4,5-positions of the central benzene core. These absorption features indicated that the PDI units in PDI-II and PDI-III are planar, whereas the PDI units in PDI-IV are twisted due to the steric crowding. Compared with the linear PDI-II, the star-shape could effectively prevent PDI-III and PDI-IV from forming large aggregates when blended with the donor polymer PBDB-T. PBDB-T:PDI-II, PBDB-T:PDI-III and PBDB-T:PDI-IV based OSCs gave power conversion efficiencies (PCEs) of 3.05%, 6.00% and 1.04%, respectively. The big differences in electron mobility and PCE for PDI-III and PDI-IV are probably due to the fact that the PDI units in PDI-III are planar and those in PDI-IV are twisted.

Two novel fused ring electron acceptors PDT and PDT-T have been designed, synthesized and used in organic solar cells. PDT comprises a central 4,10-bis(hexyloxy)-6,6,12,12-tetrakis(4-hexylphenyl)-6,12-dihydropyreno[1,2-b:6,7-b′]dithiophene (DDT) donor unit and two flanked 2-(5,6-difluoro-3-oxo-2,3-dihydro-1H-inden-1-ylidene)malononitrile acceptor units, while PDT-T has an extra thiophene bridge unit between the central donor unit and the acceptor unit. The introduction of a thiophene bridge unit can markedly broaden the absorption of acceptors and enhance the film absorption coefficient. The optical bandgaps of PDT and PDT-T are 1.59 and 1.44 eV, respectively. The photovoltaic performance of these two acceptors was investigated using PBDB-T as the electron donor. Wide photo-current responses extending to 800 nm for PDT based devices and to 900 nm for PDT-T based ones were observed. A power conversion efficiency (PCE) of 7.07% for PBDB-T:PDT based cells was obtained with a Voc of 0.96 V, Jsc of 13.48 mA cm−2 and FF of 54.0%, while the as-cast devices based on PBDB-T:PDT-T gave rise to a PCE of 11.02% with a Voc of 0.88 V, Jsc of 18.88 mA cm−2 and FF of 66.3%. These results highlight that DDT is a promising building block for constructing highly efficient fused ring acceptors and π-bridging can further boost the photovoltaic performance of the devices.

Two mutually isomeric noncovalently fused-ring electron acceptors (NC-FREAs) NOC6F-1 and NOC6F-2 containing two cyclopentadithiophene (CPDT) moieties linked at the 2,6- and 1,5-positions, respectively, of the naphthalene ring were designed and synthesized for organic solar cells (OSCs). Intramolecular noncovalent S⋯O interactions were introduced into NOC6F-1 and NOC6F-2. The tiny structural variation in NOC6F-1 and NOC6F-2 by just changing the linkage positions affects largely their molecular configuration, absorption, molecular packing, charge transport and photovoltaic performance. Compared to NOC6F-2, NOC6F-1 exhibits smaller distortions between cyclopentadithiophene and the naphthalene unit, leading to an extended conjugation and enhanced π–π stacking. NOC6F-2 exhibits a poor planarity, which restricts the electron delocalization as well as dense π–π stacking in the film form. When blended with PBDB-T, NOC6F-1 exhibits more orderly stacking along both the out-of-plane and in-plane directions than NOC6F-2. OSCs based on PBDB-T:NOC6F-2 merely showed a power conversion efficiency (PCE) of 6.74% with lower Jsc and FF values. OSCs based on NOC6F-1 achieved a higher Jsc of 17.08 mA cm−2 and an FF of 65.79%, thus leading to a significantly enhanced PCE of 10.62%. These results indicate that use of the acceptor molecules with a planar molecular backbone is an important design strategy for NC-FREAs.

Microstructures and dislocations associated with the slip band (SB) fatigue cracks were investigated in Cu single crystal and bicrystal. It is found that there are high strain localizations with abundant dislocation cells around the cracked SBs. Due to the high local strain and slip irreversibility, the lattice rotates severely leading to large misorientation and hence low- or high- angle grain boundaries could form between the neighboring cells. Moreover, the dislocation walls can serve as preferential sites for nucleation and propagation of fatigue cracks with high density of dislocations, vacancies and high strain incompatibility.

In this work, a ternary blend strategy based on PBDB-T and two small molecular acceptors (IDTT-OB and IDT-PDOT-C6) is demonstrated to simultaneously improve the photocurrent and reduce the voltage ...

In recent years, there have been intensive debates on whether healthy adults acquire new word knowledge through fast mapping (FM) by a different mechanism from explicit encoding (EE). In this study, we focused on this issue and investigated to what extent retention interval, prior knowledge (PK), and lure type modulated memory after FM and EE. Healthy young participants were asked to learn novel word-picture associations through both FM and EE. Half of the pictures were from familiar categories (i.e., high PK) and the other half were from unfamiliar categories (i.e., low PK). After 10 min and 1 wk, the participants were tested by forced-choice (FC) tasks, with lures from different categories (Experiment 1) or from the same categories of the target pictures (Experiment 2). Pseudowords were used to denote names of the novel pictures and baseline performance was controlled for each task. The results showed that in both Experiments 1 and 2, memory performance remained stable after FM, while it declined after EE from 10 min to 1 wk. Moreover, the effect of PK appeared at 10 min after FM while at 1 wk after EE in Experiment 2. PK enhanced memory of word-picture associations when the lures were from the same categories (Experiment 2), rather than from different categories (Experiment 1). These results were largely confirmed in Experiment 3 when encoding condition was manipulated as a between-subjects factor, while lure type as a within-subjects factor. The findings suggest that different from EE, FM facilitates rapid acquisition and consolidation of word-picture knowledge, and highlight that PK plays an important role in this process by enhancing access to detailed information.

We designed and synthesized two non-fullerene acceptors (CDT-TFP and C8X-TFP), which comprise a central 4H-cyclopenta[2,1-b:3,4-b′]dithiophene (CDT) as the bridge and two thiophene-fused perylene d...

A number of studies have implicated that microRNAs (miRNAs) play a critical role in the development of gestational diabetes mellitus (GDM). However, the role of miR-657 in GDM remains vague up to date. We aim to investigate the modifying effect of miR-657 on GDM, which will provide new insight into the pathogenesis of GDM and may help to identify new diagnostic or therapeutic targets for GDM. Increased expression of miR-657 but decreased expression of interleukin-37 (IL-37) was observed in patients with GDM. Besides, negative association between miR-657 and IL-37 was demonstrated in this study. miR-657 could targetedly regulate IL-37 and enhance the proliferation of mononuclear macrophages. Moreover, miR-657 promoted the generation of inflammatory cytokines (IL-6 and tumor necrosis factor-α [TNF-α]) and activation of nuclear factor κB (NF-κB) in lipopolysaccharide-induced mononuclear macrophages, while its effect was significantly inhibited when exogenous recombinant IL-37 was administrated into cells. Accordingly, dysregulation of miR-657 contributes to the pathogenesis of GDM via IL-37/NF-κB signaling axis.

Ferroelectricity and electrical conductivity are two fundamentally incompatible properties that are difficult to simultaneously achieve in a material. Here, we combine these two contradictory properties by embedding conducting SrNbO3 micro/nanopillars into a ferroelectric SrNbO3.5 (i.e., Sr2Nb2O7) thin film. The high-Tc ferroelectric SrNbO3.5 thin film is epitaxially grown on a LaAlO3 substrate by pulsed laser deposition. The conducting SrNbO3 micro/nanopillars are introduced into the film via an electron-irradiation-induced SrNbO3.5-to-SrNbO3 phase transformation triggered by a focused electron beam. The sizes and distribution of the SrNbO3 micro/nanopillars can be accurately controlled through artificial manipulation of the electron-irradiation-induced SrNbO3.5-to-SrNbO3 phase transformation. The ferroelectric SrNbO3/SrNbO3.5 thin film with an in-plane polarization exhibits an electrical conductivity in the out-of-plane direction. Such conducting ferroelectric thin films may lead to the discovery of plentiful physical phenomena and have great potential for pyroelectric, photoelectric, and multiferroic applications.

Studies have shown that the hippocampus plays a crucial role in associative memory. One central issue is whether the involvement of the hippocampus in associative memory remains stable or declines with the passage of time. In the majority of studies, memory performance declines with delay, confounding attempts at interpreting differences in hippocampal activation over time. To address this issue, we tried to equate behavioral performance as much as possible across time for memory of items and associations separately. After encoding words and word pairs, participants were tested for item and associative memories at four time intervals: 20-min, 1-day, 1-week, and 1-month. The results revealed that MTL activation differed over time for associative and item memories. For associative memory, the activation of the anterior hippocampus decreased from 20-min to 1-day then remained stable, whereas in the posterior hippocampus, the activation was comparable for different time intervals when old pairs were correctly retrieved. The hippocampal activation also remained stable when recombined pairs were correctly rejected. As this condition controls for familiarity of the individual items, correct performance depends only on associative memory. For item memory, hippocampal activation declined progressively from 20-min to 1-week and remained stable afterwards. By contrast, the activation in the perirhinal/entorhinal cortex increased over time irrespective of item and associative memories. Drawing on Tulving's distinction between recollection and familiarity, we interpret this pattern of results in accordance with Trace Transformation Theory, which states that as memories are transformed with time and experience, the neural structures mediating item and associative memories will vary according to the underlying representations to which the memories have been transformed.

To extend the absorption and enhance the electron mobility of fused-ring electron acceptors (FREAs), we designed and synthesized new FREAs (TTIC and TTIC-M) based on 4,9-dihydrothieno[3′,2':4,5]cyclopenta[1,2-b]thieno[2″,3'':3′,4'] cyclopenta[1′,2':4,5]thieno[2,3-d]thiophene (DTCTT) and 1,1-dicyanomethylene-3-indanone (IC). DTCTT unit possesses strong electron donating ability, which can broaden the absorption of the resulting acceptor molecule by enhanced internal charge transfer (ICT) effect. The S atoms on the fused ring structure can enhance the electron transport by intermolecular noncovalent S-S interaction. Furthermore, the introduction of a methyl group at the terminal IC unit can elevate the LUMO energy level of FREAs and afford higher open circuit voltage (Voc). As expected, TTIC and TTIC-M showed a broad absorption with the edge extending to the near-infrared (NIR) region (900 nm) and the optical band gaps of TTIC and TTIC-M is 1.40 and 1.44 eV, respectively. Devices based on PBDB-T:TTIC gave a PCE of 10.61% with an outstanding Jsc of 22.26 mA cm−2, a Voc of 0.77 V and an FF of 0.62. More noticeably, devices based on PBDB-T:TTIC-M provided a higher Voc of 0.80 V and a PCE of 11.48% with a Jsc of 20.51 mA cm−2 and an FF of 0.70. 11.48% is the best performance for polymer solar cells based on small band gap nonfullerene acceptors (

A novel propeller-shaped molecule (HPB-PDI6) with a hexaphenylbenzene (HPB) core and six peripheral PDI units was synthesized via Co2(CO)8-catalyzed cyclotrimerization and used as an acceptor for organic solar cells (OSCs). The intriguing geometry of the HPB core and the spatial repulsion of the PDI rings created a twisted three-dimensional propeller-shaped conformation for HPB-PDI6. The propeller-shaped conformation could prevent the acceptor molecules from forming large aggregates in the active layer. As expected, the PTB7-Th:HPB-PDI6 blend films show a favorable morphology as well as high and balanced charge carrier mobility. Devices based on PTB7-Th:HPB-PDI6 achieved a PCE of 6.63% with a Voc of 0.92 V, a Jsc of 15.11 mA cm−2, and an FF of 48.0%. Our results have demonstrated that the easily prepared propeller-shaped HPB-PDI6 could be a promising acceptor for high efficiency organic solar cells.

A novel 1,8-naphthalimide-based small molecular acceptor ( NI-T-C8 ) was designed and synthesized. The LUMO level of NI-T-C8 was high-lying, which would reduce the energy loss of WBG polymer PCDTBT-C12 based devices. When non-fullerene devices based on PCDTBT-C12: NI-T-C8 were spin-coated from substrates with a temperature of 30 °C, the aggregation of NI-T-C8 would lead to an unoptimized film morphology and result in a low power conversion efficiency (PCE) of 2.68%. After elevating the substrates from 30 to 45 °C, the domain size of blend films was decreased and a PCE of 3.61% with a high open circuit voltage ( V oc ) of 1.28 V was acquired, but the aggregation of NI-T-C8 for blend films fabricated in 45 °C based substrates was still influence the exciton dissociation in the active layers, lower J sc values for NI-T-C8 based devices in comparison to PC 71 BM based ones were therefore acquired. This is the first single junction organic solar cell with a PCE higher than 3% could achieve a V oc higher than 1.2 V. Our results also demonstrated that elevating the temperature of substrates could reduce the domain size of non-fullerene acceptors, which could provide a strategy to adjust the film morphology of active layer comprising easy-aggregating non-fullerene acceptor.

Buyers can manage product quality sourced from suppliers in three ways: they can improve the quality incoming from suppliers directly by investing in suppliers to improve a process/product, they can improve the incoming quality indirectly by incentivizing supplier quality†improvement efforts, and/or they can control the quality outgoing to subsequent processes by inspecting incoming units. In this study, we study a buyer's use of these three instruments—investment, incentives, and inspection—to manage the sourced quality. To do so, we consider a general relationship between the buyer's direct investment effort and supplier's quality†improvement effort, allowing them to be complementary, substitutable, or additive in their quality†improvement effects. For situations in which the buyer and the supplier decide their efforts simultaneously with contractible internal†failure events, we identify three types of strategies: the investment†based strategy (focusing on the buyer's investment effort) for strongly substitutable efforts, the inspection†based strategy (focusing on inspection) for strongly complementary efforts, and the integrative strategy (emphasizing all three instruments) for additive efforts. If buyer†investment commitment is possible, then the inspection†based strategy in which both parties defect in their efforts will be replaced by a collaboration†based strategy in which both parties exert high efforts to improve quality. Contracting upon external failures (in addition to internal failures) does not change this strategy pattern; however, when combined with buyer†effort commitment, such a contract achieves the first†best result.

Vinylene ( V )- and ethynylene ( E )-bridged perylene diimide dimers ( PDI-V and PDI-E ) were designed, synthesized and used as nonfullerene acceptors for polymer solar cells. Our researches revealed that the linkage between two PDI units has a great impact on the molecular geometry, the optical properties, the blend film morphology, the molecular packing orientation, and the photovoltaic performance. Computational calculations via density functional theory (DFT) showed that PDI-E and PDI-V possessed planar and twisted geometric structures, respectively. TEM investigations showed that PTB7-Th : PDI-V based blend film exhibited a uniform morphology with small domain size and PTB7-Th : PDI-E based one showed apparent phase separation with large domain size. GIWAXS results revealed that the PDI-V can influence PTB7-Th to take on a face-on orientation, which is beneficial for vertical charge transport to increase J sc . A PCE of 4.51% with a V oc of 0.76 V, a J sc of 10.03 mA cm −2 , and an FF of 0.59 was obtained for PSCs based on PTB7-Th : PDI-V , which is almost two times higher than that of PTB7-Th : PDI-E based devices, which showed a PCE of 2.66%, a V oc of 0.66 V, a J sc of 7.33 mA cm −2 , and an FF of 0.55. These results help to gain deeper insight into the design of new nonfullerene small molecular acceptors for high efficiency PSCs.

This data contains additional data related to the article “Influence of Substrate Temperature on the Film Morphology and Photovoltaic Performance of Non-fullerene Organic Solar Cells” (Jicheng Zhang et al., In press) [1]. Data include measurement and characterization instruments and condition, detail condition to fabricate norfullerene solar cell devices, hole-only and electron-only devices. Detail condition about how to control the film morphology of devices via tuning the temperature of substrates was also displayed. More information and more convincing data about the change of film morphology for active layers fabricated from different temperature, which is attached to the research article of “Influence of Substrate Temperature on the Film Morphology and Photovoltaic Performance of Non-fullerene Organic Solar Cells” was given.

Gas diffusion in multi-scale fuel cell porous media such as gas diffusion layer, microporous layer and catalyst layer affects the power performance of proton exchange membrane fuel cells. The effective gas diffusivity is one of the key parameters for gas diffusion in multi-scale fuel cell porous media, which has attracted broad interests from science and engineering. A new analytical model is presented and solved for gas diffusion in fuel cell porous media based on fractal geometry. Due to its multi-scale characteristics and existence of microscale and nanoscale pores in most fuel cell porous media, both molecular and Knudsen diffusion mechanisms are taken into account. An expression for the effective gas diffusivity of multi-scale porous media is derived, expressed in terms of bulk diffusion, pore structure as well as the Knudsen number. The proposed fractal model is validated by comparison with available experimental data and empirical correlations. The model shows that the effective gas diffusivity increases with increase of porosity and pore fractal dimension, while it decreases with increased tortuosity fractal dimension. It is believed that the current work may shed light on the gas diffusion mechanism in fuel cell porous media.

Conjugated polymers with three components, P1-1 and P1-2, were prepared by one-pot Stille polymerization. The two-component polymer P1-0 is only composed of a 5-fluoro-6-alkyloxybenzothiadiazole (AFBT) acceptor unit and a thiophene donor unit, while the three-component polymers P1-1 and P1-2 contain 10% and 20% 5,6-difluorobenzothiadiazole (DFBT), respectively, as the third component. The incorporation of the third component, 5,6-difluorobenzothiadiazole, makes the side chains discretely distributed in the polymer backbones, which can enhance the π–π stacking of polymers in film, markedly increase the hole mobility of active layers, and improve the power-conversion efficiency (PCE) of devices. Influence of the third component on the morphology of active layer was also studied by X-ray diffraction (XRD), resonant soft X-ray scattering (R-SoXS), and transmission electron microscopy (TEM) experiments. P1-1/PC71BM-based PSCs gave a high PCE up to 7.25%, whereas similarly fabricated devices for P1-0/PC71BM onl...

To explore the influence of fluoro substitution position and number on optical, electrochemical and photovoltaic properties, three novel donor-acceptor (D-A) alternative copolymers (PHF, PFH and PFF) were synthesized by Stille polycondensation of 2,3-diphenyl-5,8-di(thiophen-2-yl)quinoxaline (DTQx) acceptor unit and indacenodithiophene (IDT) donor unit. As films, PHF and PFF comprising two fluoro substituents on the lateral phenyl groups displayed a broad absorption ranging from 350 to 700 nm; whereas PFH containing two fluorine atoms on the polymer main chain exhibited a slightly narrower absorption ranging from 350 to 650 nm. In addition, fluoro substitution on the polymer main chain can lower the HOMO level of the resulted polymers. As expected, PFH and PFF possess deeper HOMO energy level than PHF. Polymer solar cells (PSCs) were fabricated with these three polymers as donor materials and PC71BM as acceptor material. PHF based PSCs gave a power conversion efficiency (PCE) of 7.2% with a Voc of 0.84 V, a Jsc of 12.46 mA/cm2 and an FF of 0.69. And PFH based PSCs showed a PCE of 6.19% with a Voc of 0.93 V, a Jsc of 9.57 mA/cm2 and an FF 0.70. However, a PCE of only 2.9% with a Voc of 0.92 V, a Jsc of 4.61 mA/cm2 and an FF of 0.68 was obtained for PFF based PSCs. Transmission electron microscopy (TEM) and resonant soft X-ray scattering (R-SoXS) studies indicated that the introduction of four fluorine atoms at each repeating unit can spoil the morphology of active layer. These results highlight the importance of fluorination position and number to the performance of PSCs.

Martensitic transformation and deformation twinning are investigated in Ti-24Nb-4Zr-8Sn (wt. %) alloy with in situ tensile deformation in scanning and transmission electron microscopes. Deformation-induced β to α″ martensitic transformation occurs at a stress plateau stage of ∼200 MPa and deformation twinning takes place subsequently at later strain hardening stage. In situ transmission electron microscopy observations combined with finite element method calculation reveal that three deformation mechanisms, α″ martensitic transformation, {112} β deformation twinning and kinks of α″ lamellae, are activated with the increase of applied stress/strain. Among them, deformation-induced β to α″ phase transformation dominates the early-stage deformation. As the stress increasing, {112} β deformation twinning is activated and becomes the dominating deformation mechanism afterward. Interactions between dislocation slips and martensite/twin lamellae are likely responsible for the strain hardening. After the deformation over the ultimate tensile strength, slip bands initiate and become the major deformation mechanism during necking until fracture.

A novel medium band gap copolymer ( PBO ) based on benzodithiophene (BDT) and benzoxadiazole (BOz) was synthesized and applied in polymer solar cells (PSCs). The introduction of two alkylthio side chains onto the BDT unit can endow the resulting polymer ( PBO ) with good solubility in solutions and good crystallinity in the solid state. The low HOMO level of −5.52 eV and the broad absorption ranging from 350 to 700 nm make PBO a promising donor material for PSCs. Power conversion efficiency higher than 7% has been achieved for devices using PBO as the donor material and PC 71 BM or ITIC as the acceptor material.

Novel polymers comprising a 3-fluoro-5-alkylthiophenyl benzodithiophene donor unit and a 5-fluoro-6-alkoxy (or alkylthio)-2,1,3-benzothiadiazole (BT) acceptor unit were synthesized. Both POF and PSF possess low HOMO and LUMO energy levels due to the incorporation of fluorine atoms. Additionally, alkoxy and alkylthio substitution on the BT unit also had a great influence on the molecular packing and the energy level of the resulting polymers. The introduction of the alkylthio side chains on the BT unit of PSF led to a significant downshift of the HOMO energy level in comparison to that of POF with an alkoxy substituent due to the weaker electron-donating properties of the sulfur atom than that of oxygen. However, the steric hindrance caused by the large sulfur atoms resulted in reduced planarity of the backbone of PSF, which might influence the charge transport and the morphology of the blend film. As a result, POF based NF-PSCs exhibited a PCE of 7.28%, with a Voc of 0.86 V, a Jsc of 14.9 mA cm−2, and an FF of 0.47, while a low PCE of 1.55% with a Voc of 0.95 V, a Jsc of 5.6 mA cm−2, and an FF of 0.29 was obtained for PSF based non-fullerene polymer solar cells (NF-PSCs). Therefore, the side chain engineering of the donor polymer is crucial for maximizing both Jsc and Voc values to achieve high performance polymer solar cells.

For the first time, a hyperbranched polymer acceptor, HP-PDI, was designed, synthesized and applied in polymer solar cells (PSCs). Devices based on HP-PDI showed a power conversion efficiency of 2.15%, which is 14 times higher than that of devices based on the small molecular acceptor SM-PDI. The hyperbranched structure can effectively suppress the aggregation of PDI molecules preventing them from forming large domains. Our preliminary results have demonstrated that high efficiency PSCs could be achieved by using a hyperbranched polymer acceptor.

Polarization property characterization of the microwave (MW) field with high speed and resolution is vitally beneficial as the circularly-polarized MW field plays an important role in the development of quantum technologies and satellite communication technologies. In this work, we propose a scheme to detect the axial ratio of the MW field with optical diffraction limit resolution with a nitrogen vacancy (NV) center in diamond. Firstly, the idea of polarization selective detection of the MW magnetic field is carried out using a single NV center implanted in a type-IIa CVD diamond with a confocal microscope system achieving a sensitivity of 1.7 &mu, T/ Hz . Then, high speed wide-field characterization of the MW magnetic field at the submillimeter scale is realized by combining wide-field microscopy and ensemble NV centers inherent in a general CVD diamond. The precision axial ratio can be detected by measuring the magnitudes of two counter-rotating circularly-polarized MW magnetic fields. The wide-field detection of the axial ratio and strength parameters of microwave fields enables high speed testing of small-scale microwave devices.

In order to explore the modification effect of carbonization time on nano-MgO-modified cement soil, unconfined compressive strength tests of nano-MgO-modified cement soil with carbonization times of 0 h, 6 h, 1 d, 2 d and 4 d were carried out. A method for normalizing the stress–strain curve was proposed, and the influence of nano-MgO content and carbonization time was investigated from the three aspects of compressive strength, peak strain and energy dissipation. The test results show the following: (1) The compressive strength of the modified cement soil can be significantly improved by adding 1.0% nano-MgO and after 1 d carbonization. (2) Under the same nano-MgO content, the peak strain of the modified cement soil after 2 d carbonization reaches the maximum, which can significantly increase its ductility. However, the nano-MgO content has little influence on the peak strain of the modified cement soil. (3) Under the same nano-MgO content, the energy dissipation rate of the modified cement soil after 1 d carbonization reaches the maximum, which can better resist the damage of external load.

Non-fused ring electron acceptors with varied substituents were developed to construct efficient organic solar cells (OSCs). Out-of-plane rigid substituents such as 2-methylphenyl, 2-tert-butylphenyl and diphenylamine were introduced to the central benzene unit to improve the solubility of non-fused ring acceptors and noncovalent interactions such as O⋯S and N⋯S were used to enhance the planarity of molecular backbones. Blend films based on PBDB-T and these acceptors displayed better morphology without oversized aggregates formed. As-cast devices based on SM1, SM2 and SM3 exhibited power conversion efficiencies of 5.96%, 6.43% and 6.80%, respectively.

Two simple dithienosilole unit (DTS)-based nonfused small molecular acceptors (SiOC2C6–4F and SiOC2C6–4Cl) using two DTS moieties linked alkoxyl substituted benzene ring as the central core (D) and bis(5,6-difluro-3-oxo-2,3-dihydro-1H-indene-2,1-diylidene)dimalononitrile or bis(5,6-dichloro-3-oxo-2,3-dihydro-1H-indene-2,1-diylidene)dimalononitrile as the end groups have been synthesized. The optical, electrochemical properties and device photovoltaic performance of these two molecules were investigated in detail. DFT results indicates S⋯O interactions involving alkoxyl groups of benzyl rings and thienyl S atoms of DTS can act as conformational “locks” to enhance molecular planarity. when the polymer PBDB-T was chosen as the donor, the PBDB-T:SiOC2C6–4F-based device provided a high PCE of 9.68% with a Voc of 0.90 V, a Jsc of 17.02 mA/cm2 and an FF of 63.00%, while the PBDB-T:SiOC2C6–4Cl-based device exhibited a PCE of 11.29% with a Voc of 0.87V, a Jsc of 20.35 mA/cm2 and an FF of 63.73%, which is so far the best performance reported for organic photovoltaic using silole-based small-molecule acceptors.

A series of PDI-based small molecular acceptors (FPDI-I, FPDI-II, F2PDI-I and F2PDI-II) using 9H-fluorene as the central core and two PDI units or two PDI dimer units (PDI2) as the terminal groups have been synthesized. The optical, electrochemical and photovoltaic properties of these four acceptors have been systematically investigated. These acceptors exhibit twisted structures mainly due to the dihedral angles between the central fluorene core and the two terminal PDI units. The twisted molecular structures can effectively prevent the acceptor molecules from forming oversized aggregates. The two terminal fused PDI dimer units in F2PDI-I and F2PDI-II can enhance their molar absorption coefficients. Using PBDB-T as the donor polymer, F2PDI-I and F2PDI-II based devices exhibit higher and more balanced charge mobilities. As a result, organic solar cells (OSCs) based on PBDB-T:F2PDI-I give the best device performance with a power conversion efficiency (PCE) of 6.82%, a Voc of 0.90 V, a Jsc of 11.32 mA cm−2 and an FF of 66.65%.

Two donor-acceptor alternative copolymers ( P1 and P2 ) with carbazole group as the donor unit and 2,3-diphenylquinoxaline group as the acceptor unit were designed and synthesized by Suzuki polycondensation reaction. Alkoxy groups were linked to meta-position or para-position of phenyl rings, which were attached on the 2,3-position of quinoxaline group to investigate the effect of the alkoxy position at phenyl rings on the resulting polymer optical, electrochemical and photovoltaic properties. GIWAXS experiments revealed that para-substituted polymer P2 possesses closer packing properties in the solid state. The absorption spectra of para -substituted polymer P2 also displayed larger red-shift than that of meta-substituted polymer P1 when it went from solution to the film, which was beneficial to improve the hole mobilities and short circuit current density ( J sc ). When used as the donor materials, devices based on P2:PC 71 BM exhibited a PCE of 3.33%, which was obviously higher than that based on P1:PC 71 BM. Our results revealed that the slightly structure change of polymer has a significant influence on the photovoltaic properties of polymer solar cells and adopting para-substituted phenyl ring as the side groups gave superior photovoltaic performance in donor materials based on carbazole and quinoxaline.

Three novel copolymers ( PTTAFBT-C0 , PTTAFBT-C1 and PTTAFBT-C2 ) based on thieno[3,2- b ]thiophene and 5-alkoxy-6-fluorobenzo-[ c ][1,2,5]thiadiazole (AFBT) bearing branched alkoxy chains with varied branching positions are synthesized. The influences of the bifurcation positions on intermolecular stacking, charge mobility, film morphology and photovoltaic performance are systematically investigated. 2D-GIWAXS analyses of the optimized polymer:PC 71 BM blend films exhibit the crystallinity increases from PTTAFBT-C0 to PTTAFBT-C1 and PTTAFBT-C2 is more prone to form the edge-on orientation than PTTAFBT-C1 , which result in a dramatic difference in film morphologies. TEM image of PTTAFBT-C1 :PC 71 BM blend films exhibits a suitable morphology with favorable interpenetrating networks, which is in favor of high performance. The best PCE of 5.67% with a device configuration of ITO/PEDOT: PSS/ PTTAFBT-C1 :PC 71 BM/LiF/Al under AM 1.5G solar radiation (100 mW cm −2 ) is achieved. These results indicate that higher PCE can be obtained by adjusting the bifurcation points of the branched side chains away from the polymer backbone.

Gas transport properties in micro and nano-scale porous media are of significance for low-permeability reservoirs. Gas slippage and gas molecular diffusion in micro- and nano-pores take important effect on the gas permeability of porous media. Therefore, gas effective permeability of micro and nano-scale porous media over the entire Knudsen regime is presented by a fractal model. The analytical expression for gas effective permeability with Klinkenberg effect which is a function of structural parameters of porous media (porosity, fractal dimensions and pore diameter) and gas property (mean free path of gas molecule) is derived based on the microflow model and fractal capillary model. In order to further address the local flow field characteristics, numerical simulations are also performed on a fractal Sierpinski carpet. The fractal model is validated by comparison with available experimental results, and the effect of gas slippage on the gas permeability is discussed also. The present results indicate that gas effective permeability with slippage effect increases with the increase of fractal dimension for pore size distribution and decreases as the fractal dimension for tortuosity increases. And the gas slip factor increases with the decrease of pore size, it can be also increased by increased fractal dimension for pore size distribution under fixed maximum pore size and porosity. The current fractal model can characterize the multi-scale microstructures in porous media, and every parameter in the proposed gas effective permeability model has specific physical meaning.

The branching structures and bifurcation flows in human lung are crucial factors for the functioning of the respiratory system. In this paper, both steady and unsteady flow in a symmetrical bronchial tree have been investigated, and the global and local transport properties are explored by fractal geometry and computational fluid dynamics method, respectively. Firstly, total flow properties for steady laminar flow and pulsatile flow in a fractal tree-like network are derived, and the global fluid dynamics behavior under volume constrain is discussed accordingly. And then, a mathematical model is developed for the steady and unsteady gas flow as well as gas-particle two-phase flow in a four-generation bifurcation in order to study the local transport characteristics of bronchial tree. The results indicate that the critical successive diameter ratio for the first few generations is below the prediction of Murray’s law while small airways follow Murray’s law. It has been also shown that the asymmetrical and non-uniform flow distribution can be realized through a symmetric branching structure with increased Reynolds number. The asymmetric ratio is found to be scaled with the Reynolds number as χ ∼ Re 0.00124 in the steady respiratory condition. The effect of Reynolds number and respiratory frequency on the flow distribution and particle deposit efficiency are studied for different respiratory conditions, which show that the particle deposit efficiency can be increased with increased Stokes number. The present work is important for the morphology of the bronchial tree and understanding the physical mechanism of the bifurcation flow.

A thermo-cleavable fullerene derivative was used as an interfacial engineering material in planar perovskite solar cells. The modified TiO2 surface shows exceptional resistance against polar solvent washing and the perovskite film grown on it was of high quality with less pinholes. Consequently, high performance devices without hysteresis have been achieved.