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Based on the unique structure, excellent physical and mechanical properties of graphene nanosheets (GNSs), thermal decomposition method was used to modify the GNSs for preparing Ni-modified GNSs (Ni-GNSs) in this paper. Varying amounts of Ni-GNSs were added to SnAgCuRE solder alloy to synthesize composite solders. The soldering behaviors of the composite solders were studied, and the strengthening mechanism of Ni-GNSs on the SnAgCuRE lead-free solder/Cu joints was discussed. Compared with Sn2.5Ag0.7Cu0.1RE0.05Ni solder alloy joint, the interfacial IMC morphology of Ni-GNSs/SnAgCuRE composite solder joints changed from cobblestone to cobblestone and short bar, the interfacial IMC layer thickness was smaller, the IMC grains and microstructure of solder joints were refined. The addition of GNSs changed the structure of the composite solder/Cu joints, and formed a subinterface area enriched with Ni-GNSs between the interfacial IMC and the soldering seam, which helped enhance the reliability of the composite solder joints through the dispersion strengthening of solder by GNSs. Meanwhile, the fracture location of the solder joint was in the soldering seam, so strengthening the solder alloy was also beneficial to improving the strength of the solder joints. After modified by Ni, GNSs was combined with β-Sn matrix to produce a good semi-coherent interface by the bridging action of Ni, revealing a new mechanism of interface strengthening between Ni-GNSs and β-Sn matrix in Ni-GNSs/SnAgCuRE composite solder, which contributed to the improvement of shear strength of composite solder joints.

Conventional engineered surfaces for fluid manipulation are hindered by the set wettability, and thus they can only achieve spontaneous transport of single-phase fluid, namely liquid or gas. Moreover, fluid transport systems that are robust to path defects have yet to be fully explored. Here, unprecedentedly, a universal wettability switching strategy is developed for achieving programmable directional transport of both droplets and subaqueous bubbles on a dumbbell-patterned functional surface (DPFS), featuring in strong robustness, high efficiency and effective cost. By tuning the superwettability of DPFS through octadecyltrichlorosilane treatment and ultraviolet-C selective irradiation, the transport fluid can alternate between liquid and gas. The material's switchable superwettability regulates the fluid directed dynamics within the confined pattern, in which the sustaining fluid propelling relies on the surface energy difference between the starting and terminal sites. This enables the construction of multiple channels, which works synergistically with ultralow-volume-loss transport to impart the fluidic system with strong robustness against path defects. Underlying the completion of complex microfluidics tasks, spatially-selective cooling devices and subaqueous gas microreactors are successfully demonstrated. This energy-consumption-free fluid transport system opens a new avenue for on-chip programmable fluid manipulation, promoting innovative applications requiring rational control of two-phase fluid transport. This article is protected by copyright. All rights reserved.

Zinc titanate phosphors containing Eu

Allergen-specific immunotherapy (AIT) has been employed in the treatment of allergic diseases for many years. However, the effectiveness of AIT requires improvement. Substance P (SP) can interact with immune cells, modulate immune cell activity, and regulate immune reaction. The purpose of this study is to use SP as an immune regulator to enhance the therapeutic efficacy of AIT.An established mouse model of the airway allergy disorder (AAD) was employed with ovalbumin as a specific antigen. The AAD response was evaluated through established procedures. AAD mice were treated with AIT employing SP as an immune regulator. Dendritic cells were isolated from the airway tissues by magnetic cell sorting, and were analyzed by RNA sequencing (RNAseq).We observed that after sensitization with ovalbumin, mice exhibited AAD-like symptoms, serum specific IgE, and Th2 polarization. The presence of SP in the course of sensitization prevented the development of AAD. Treating mice with SP by nasal instillations induced IL-10, but not TGF-β, in dendritic cells of the airway tissues. The most differentially expressed genes (DEG) in the dendritic cells were those related to the IL-10 expression, includingActing as an immune regulator, SP promotes the therapeutic efficacy for AAD by inducing antigen specific Tr1 cells in the airway tissues.

To save test time and cost, spreading area method and wetting balance method were used to study the wetting characteristics of Ni-GNSs/SnAgCuRE composite solder under different parameters and explore the correlation between spreadability and wetting driving force of the composite solder. The results showed that the composite solder had good spreadability on the Cu substrate under 270–280 °C and water-clean flux, and they had good wetting adaptability to Cu wire under the tin bath temperature of 270–280 °C, dipping time of 6 s and dipping speed of 20 mm/s. The results satisfied the requirements of production in micro-connection field. The dynamic spreading processes of Ni-GNSs/SnAgCuRE composite solder consisted of three stages: initial slow shrinkage, rapid expansion and gradual equilibrium. Added appropriate amount of Ni-GNSs into the solder alloy, they adsorbed on the surface of Ag3Sn particles to form a precursor film at the three-phase interface, which was conducive to spread. The correlation equation between spreadability and wetting driving force of composite solder was established. According to the spreading area of the composite solder on the Cu substrate, the wetting driving force and wetting balance of the immersion wetting processes could be analyzed and vice versa.

This polymer microstructure expands more available application, which is a milestone for the development of micro-electro-mechanical system devices towards intelligence and multifunction. Poor interface bonding between the polymer and Si or metal is a particular problem, which restricts the application and promotion of polymer materials. In this study, a transition strengthening layer is proposed to obtain a highly stable polymer microstructure by enhancing the interfacial adhesion strength. The transition strengthening layer is activated by a pushpin-like nano/microstructure array with micromachining technology. Given its good graphical qualities and compatibility, epoxy negative photoresist SU-8 is applied to evaluate the strengthened capabilities of the pushpin-like nano/microstructure array. The microstructure of SU-8 is prepared by the same processes, and then the adhesion strength between the SU-8 microstructure and various activated substrates is tested by the thrust tester. It was determined that SU-8 with an activated pushpin-like microstructure array possessed a highly stable adhesion ability, and its adhesion strength increased from 6.51 MPa to 15.42 MPa. With its ultrahigh stable adhesion ability, it has been applied in fabricating three typical microstructures (hollow square microstructure, gradually increasing adjacent periodic microstructure, and slender strip microstructures) and large-area SU-8 microstructures to evaluate the feasibility of the transition strengthening layer and repeatability and universality of the microfabrication processes. The drifting and gluing phenomenon are avoided by this method compared with the traditional design. The proposed pushpin-like nano/microstructure array is promising in enhancing the stability of polymer microstructures with a substrate.

To meet the diversified development of electronics, it is essential to develop 3D metal microstructures with high performance. However, 3D thick silver forming is still a challenge due to high internal stresses and various defects. Here we proposed a method for the thick Ag electrodeposition with low-stress and high chemical stability for 3D Ag-based microstructures. We carried out systematic studies through electrochemical measurements, morphological characterization, micro-texture analysis, internal and stability examination. The results show that the nucleation mechanism of electroplating Ag is transformed from progressive nucleation to instantaneous nucleation through the coordinated control of current density and temperature. Higher temperature and lower deposition potential are preferred to form the large-grained crystallization. Additionally, the external parameters for fabricating Ag coating were optimized, and the correlation between micro-texture and internal stress was also verified. The feasibility of thick Ag preparation process was demonstrated by extending the electroplating time, showing excellent performance. Finally, 3D Ag micropillar arrays with the height of 577 μm and the high aspect ratio close to 3 were fabricated by MEMS processing techniques, displaying satisfied 3D forming ability. This work presents a new approach for manufacturing the 3D Ag microstructures and lays foundation for the multi-functionalization Ag-based devices.

Palladium film hydrogen sensor based on suspended micro hotplate has been fabricated to operate at elevated temperature with low power consumption. Below 150 °C, the response of the sensor to H2 is represented by an increase in resistance. At higher temperature, the phenomenon of resistance reduction appears when it comes into contact with H2. We have researched the reasons for this phenomenon and proposed that the sensitive mechanism is the redox reaction of Pd film on the suspended structure. The suspended substrate can affect the temperature at which redox of the Pd film occurs, and be sensitive to the changes of the surrounding gas stream. When the working temperature is 400 °C, the magnitude of response (S) changes to −0.4% within 2 s for 200 ppm H2, and S changes to −3% within 10 s for 4000 ppm H2. This micro hotplate based hydrogen sensor can control the range of operating temperature according to the performance requirements.

Based on the self-built corpus, Disgrace is compared with Coetzee’s other 11 novels with AntConc to generate keyword list and the data reveals that "dogs", as an important keyword, makes a great contribution to theme construction of Disgrace and has a relationship of co-occurrence and isomorphism with man. Dogs are the objects of Lurie’ gaze, and with anti-gaze, he achieves empathy between man and dogs, clarifies the identity of dogs as companion species of human beings, showing the isomorphism between them. Lurie’s becoming dog-man, which is, in essence, a kind of deterritorialization, breaking through the species boundary between humans and animals and demonstrates the animal rights.

With the development of microelectronics, power density continues to rise, which has put forward higher requirements for the thermal management. At present, the microchannel heat sinks have been investigated as an efficient way for heat dissipation for a long time. However, the optimization of microchannel heat sink is always concentrated on two-dimensional plane structure. In this paper, we proposed a hierarchical microchannel heat sink for heat transfer enhancement. Taking micro pin fin as an example, we designed three different hierarchical pin fins, and the model with the best performance is obtained through simulation under the Reynolds number from 1500 to 5500. The hierarchical heat sink shows better heat transfer performance than traditional heat sink, which is attributed to the flow field reconstruction with no significant increase in pressure drop. Typically, when the upper size (Wp1) of hierarchical pin fin increases to 375 μ m , the maximum Nusselt number reaches 21 with the thermal performance factor up to 1.03 under the Reynolds number of 5500. Experimentally, three sizes of pin fins have been prepared and examined, and the results show that the heat loads exceeding 700 W/cm2 can be dissipated with the maximum temperature rise of 52 K, which is well matched with the simulation results. Anyway, the proposed in this work shows great potential in heat dissipation of electronics.

As chemical sensors are in great demand for portable and wearable analytical applications, it is highly desirable to develop an all-solid-state ion-selective electrode (ISE) and reference electrode (RE) platform with simplicity and stability. Here we propose a wearable sensor platform with a new type of all-solid-state ISE based on a gold nanodendrite (AuND) array electrode as the solid contact and a poly(vinyl acetate)/inorganic salt (PVA/KCl) membrane-coated all-solid-state RE. A simple and controllable method was developed to fabricate the AuNDs on a microwell array patterned chip by one-step electrodeposition without additional processing. For the first time, the AuND electrodes with different real surface area and double layer capacitance were developed as solid contact of the Na+-ISE to investigate the relationship between performance of the ISE and surface area. As-prepared AuND-ISE with larger surface area (∼7.23 cm2) exhibited enhanced potential stability compared to those with smaller surface ar...

Flexible mechanosensors with a high sensitivity and fast response speed may advance the wearable and implantable applications of healthcare devices, such as real-time heart rate, pulse, and respiration monitoring. In this paper, we introduce a novel flexible electronic eardrum (EE) based on single-walled carbon nanotubes, poly-ethylene, and poly-dimethylsiloxane with micro-structured pyramid arrays. The EE device shows a high sensitivity, high signal-to-noise ratio (approximately 55 dB), and fast response time (76.9 μs) in detecting and recording sound within a frequency domain of 20–13,000 Hz. The mechanism for sound detection is investigated and the sensitivity is determined using the micro-structure, thickness, and strain state. We also demonstrated that the device is able to distinguish human voices. This unprecedented performance of the flexible electronic eardrum has implications for many applications such as implantable acoustical bioelectronics and personal voice recognition.

In conventional discontinuous deformation analysis (DDA), the procedure called open–close iteration is adopted to enforce the contact condition, which needs to repeatedly fix and remove the...

OBJECTIVE: To investigate the diagnosis and evaluation methods of nasal bone fractures after nasal trauma, and the guiding significance of three-dimensional CT imaging technology for its treatment. METHOD: A total of 255 patients with nasal bone fractures were randomly selected from our hospital. All patients underwent CT scan of the nasal bones and reconstructed on a computer system. The reconstructed CT images were observed, measured and evaluated. Analyze the morphological characteristics of nasal bone fractures and evaluate the involvement of other facial structures. RESULT: Among 255 patients with nasal trauma, there were traumatic nasal bone fractures, including 71 cases(27.8%) with simple nasal bone fractures, 143 cases(56.1%) with traumatic nasal septum deviation, and 41 cases(16.1%) with other fractures. External nasal fracture classification: type Ⅰ(unilateral nasal bone or maxillary frontal fracture) 91 cases(35.7%), type Ⅱ(bilateral nasal bone or fracture) 21 cases(8.2%), type Ⅲ(with trauma Nasal septum deviation) 143 cases(56.1%). A total of 214 patients(83.9%) underwent surgical treatment, and underwent nasal endoscopic reduction of nasal bone fractures under local anesthesia, and 77 patients(30.2%) underwent nasal septum surgery. CONCLUSION: CT three-dimensional imaging technology can clearly display the location of the nasal bone fracture, the shape of the fracture line, the number of fragments formed by the fracture, and quantitative analysis of the deformity caused by it, which plays an important role in its diagnosis and treatment.

A modified 360° netting vein bionic structure is proposed to improve the thermal properties of the composite. The influence of the fillers’ distributed configuration on the composite thermal conductivity is analyzed with finite element method to optimize the filling ratio, filling angle and distributed form. With the purity and prewetting processes, the surface roughness and wetting property of SiC nano-fiber (SiCnf) is improved. By adjusting the magnetic stirrer speed, the viscosity of Polyimide (PI) and filling ratio, a configuration of SiCnf in vertical direction is achieved for transferring heat and relieving stress effectively. Cu pillar serving as the main vein is fabricated with photography and electroplating. The thermal conductivity increases more than 40 times comparing with the pure PI. After mechanical loading test, fillers and Cu pillar are still reliable. Thus, this design has potential for transferring heat and relieving stress, just liking leaf vein system.

Constructing a novel molecular architecture and creating far-red/near-infrared (FR/NIR) fluorophores with aggregation-enhanced emission (AEE) and solution film-forming ability is of particular interest but has been so far unreported. Here we linked two butterfly-shaped 3,7-bis(alkoxyphenylbenzothiadiazol)phenothiazines by an alkyl spacer to form a pair of conjoined donor–acceptor butterflies (SP6) as FR/NIR electroluminescent emitters. SP6 was found to be a multifunctional dye exhibiting AEE characteristics and reversible mechanofluorochromism, and significantly, a good quality film with strong deep-red emission could be formed by spin-coating the solution. The simplest solution-processed device (ITO/PEDOT:PSS/SP6/CsF/Al) emitted NIR light of 683 nm with a peak external quantum efficiency (EQE) of 0.57% and a CIE coordinate (0.68, 0.31). When the hole-transporting PVK layer was introduced, the still simple solution-processed device (ITO/PEDOT:PSS/PVK/SP6/CsF/Al) emitted FR light of 659 nm with a remarkably increased EQE of 1.82% and a CIE coordinate (0.65, 0.34). The low efficiency roll-offs and high radiative exciton ratios breaking through the theoretical limit signified that the rational modification and integration of the existing EL emitters could develop promising solution-processable EL materials having an inherent light-emitting mechanism.

In this paper, we have synthesized our simple twisting arylvinyl anthracene derivatives, 9-styrylanthracene ( ASB ), 9,10-bis(styryl)anthracene ( SB ), 9-(2-(naph- thalen-1-yl)vinyl)anthracene ( ASN ) and 9,10-bis((naphthalen-1-yl)vinyl)anthracene ( SN ), to demonstrate the effect of skeleton symmetry on optical and optoelectronic properties. The results showed that SB and SN are weak emission with the fluorescence quantum yields ( Φ ) of ca. 7% but ASB and ASN are highly fluorescent ( Φ ≈50%) in THF solution, although they all exhibit high solid-state fluorescence efficiencies (22~50%). Grinding could induce about 20 nm of spectral shift of ASB and ASN crystalline fluorescence, but SB and SN crystals hardly exhibit mechano- fluorochromic behavior. Furthermore, the evaporated films of SB and SN are fragile due to re-crystallization soon, but those of ASB and ASN are stable and could be used as the bulk emissive layer exhibiting commendable electroluminescent performances. This finding indicates that the geometric structures of conjugated skeletons could influence the electronic and aggregate structure of organic luminogens, and then alter their optical and optoelectronic properties.

The thermal effect of diode pumped solid-state laser (DPSSL) has always been a main problem limiting the further improvement of laser performance. In this paper, based on the special heat load distribution of the laser crystal of diode partially end-pumped slab (Innoslab) laser, a multi-stage manifold rectangular microchannel heat sink (MCHS) with high thermal conductivity path (HTCP) is designed. The multi-stage manifold provides the MCHS more fluid-solid heat transfer area near the heat gathering area, while the HTCP provides a path for heat transmission from pump end to the body of MCHS. According to simulation calculation, the highest temperature of laser crystal has been reduced by nearly 50? due to the addition of HTCP. Then the MCHS is fabricated by MEMS technology and the laser crystal is replaced by simulated heat source. Compared with the MCHS without the HTCP, the thermal resistance of the MCHS with HTCP is reduced by 6.4%, which proves the effectiveness of HTCP in heat dissipation of Innoslab laser crystal.

A hybrid assembly of cationic methylene blue (MB) with calcium niobate (Ca2Nb3O10–) nanosheets was fabricated by electrostatic self-assembly deposition (ESD) method. The obtained MB–Ca2Nb3O10 nanocomposites were characterized by a variety of analytical techniques such as XRD, FTIR, SEM and TG–DTA. Interlayer spacings determined from XRD patterns reveal that MB+ cation form an inclined monolayer arrangement with its long molecular axis being tilted approximately 46° against Ca2Nb3O10– nanosheets. The intercalated MB cations showed a fine diffusion-controlled electrochemical redox process and exhibited excellent electrocatalytic activity towards ascorbic acid (AA) oxidation in neutral media. Differential pulse voltammetry studies demonstrated that the intercalation nanocomposite detects AA linearly over a concentration range of 1.0 × 10−4 M to 8.3 × 10−3 M with the detection limit of 4.6 × 10−5 M at a signal-to-noise ratio of 3.

The torsion angle and distance between the donor (D) and the acceptor (A) are two important factors in determining the photoluminescence and electroluminescence properties of twisted D–A type organic molecules. Here, two new D–A compounds, 2-(10-butyl-10H-phenothiazin-3-yl)-5-phenyl-1,3,4-oxadiazole (PO) and 2-(4-(10-butyl-10H-phenothiazin-3-yl)phenyl)-5-phenyl-1,3,4-oxadiazole (PPO), were designed and synthesized to tune the torsion angle and distance between D and A moieties, and their photophysical and electroluminescence properties were investigated. The D–A type molecule PO has a planar conformation, whereas the D–π–A type molecule PPO has a twisted conformation because of the insertion of the phenyl bridge between the donor and the acceptor. Therefore, the charge transfer (CT) of PPO is much stronger than that of PO, and the singlet exciton yield of PPO may be higher than that of PO. On the other hand, the introduction of a phenyl unit can also improve the photoluminescence quantum efficiency (doped film ΦPL ≈ 70%). As a result, the PPO-doped device showed better device performance than PO. The device based on PPO as an emitter exhibited stable and high luminous efficiency (15.2 cd A−1, corresponding to an external quantum efficiency of 5.4%), which is increased by about 1.05 fold as compared to the device based on PO as an emitter (luminous efficiency 7.4 cd A−1 and external quantum efficiency 2.9%).

Objectives Accumulating evidence demonstrated that the long noncoding RNA (lncRNA) HOTAIR (Hox transcript antisense intergenic RNA) plays key role in renal cell carcinoma (RCC) malignancy, while microRNA-124 (miR-124) is a tumour suppressor in RCC. The aim of this work was to assess the biological function of HOTAIR and to explore underlying mechanism involved in HOTAIR/miR-124/alpha-2, 8-sialyltransferase 4 (ST8SIA4) axis-regulated progression in RCC. Materials and methods Real-time PCR analyses and western blots were performed to the levels of HOTAIR, miR-124 and ST8SIA4 expression in human RCC tissues and RCC cell lines (ACHN and 786-O). Bioinformatics analysis and dual-luciferase reporter assay were used to illustrate relationship between HOTAIR and miR-124 in RCC. Colony formation assays, EdU assays, Ki67 assays and apoptosis assays were taken to evaluate cell proliferation. Tumour xenograft was created to explore the functions of HOTAIR and ST8SIA4 in tumorigenesis in vivo. Migration assays, invasion assays and cell adhesion assays and were also taken to analyse the carcinoma progression. Results In this study, HOTAIR level was confirmed to be significantly upregulated in RCC samples and RCC cell lines compared with those in the paired adjacent tissues and normal renal cell line. Overexpression of HOTAIR promoted the capability of proliferation, migration and invasion in RCC cell lines. HOTAIR directly bound to miR-124, while miR-124 mediated the expression of ST8SIA4 in RCC cell lines. ST8SIA4 was upregulated in RCC tissues and RCC cell lines. Ectopic expression of ST8SIA4 modulated the proliferation, migration and invasion of RCC cells. Further results indicated that HOTAIR promoted the proliferation and metastasis as a competing endogenous RNA to regulate ST8SIA4 expression by sponging miR-124 in RCC. Conclusions Our results demonstrated that HOTAIR mediated RCC progression in part through miR-124/ST8SIA4 axis, which functioned as a new prognostic biomarker in RCC.

Herein, the use of a 2D soft template system composed of hundred-nanometer-thick water/ethanol mixed layers sandwiched by lamellar bilayer membranes of a self-assembled amphiphilic molecule to produce ultrathin polyprrole (PPy) with a uniform thickness as thin as 3.8 nm and with large dimensions (>2 μm(2)) is presented. The obtained PPy nanosheets exhibit regioregularity with ordered chain alignment where the polymer chains in the nanosheets produced are well aligned with a clear interchain spacing as confirmed by small-angle X-ray scattering measurement. The molecular-level-thick PPy nanosheets exhibit extremely high conductivity up to 1330 S m(-1), thanks to the ordered alignment of polymer chains in the nanosheets, and a high transparency in both the visible region (transmittance >99%) and near-infrared region (transmittance >93%).

To investigate the possibility and anatomy landmark of the frontal beak approach of endoscopic frontal sinusotomy to the frontal sinus lesions.(1)Twenty cases of frozen cadaveric head underwent spiral computed tomography scans. Then data were transferred into the Mimics image workstation to reorganize CT images in the coronal, sagittal, and axial planes. The anatomic parameters related to surgical approach points were measured, such as the distance between vertical plate of the middle turbinate and lamina papyracea and the thickness of the frontal beak. (2) 3D visual model of the frontal cell and the drainage way of the frontal sinus was produced with the application of Sinuses Trachea I software. (3)The endoscopic frontal sinus surgery were performed on 20 cases of subjects (objects)to find out the anatomy landmarks of the frontal beak approach, measure the parameters such as the distance between middle turbinate and lamina papyracea, and evaluate the potential surgical complications during operation.(1)The frontal beak is a white bony arcs located at the attachment point of middle turbinate front inserted to the skull base. Its position was relatively constant, before frontal sinus above. (2)The distance between the middle turbinate vertical plate and lamina papyracea was (7. 61 ± 1. 34) mm. The thickness of the frontal beak in surgical approach was (3. 27 ± 0. 91) mm. (3) 3D visual structure of the frontal sinus and its ventilation pathway: the shape of unilateral frontal sinus looked like the cone, which was transited by the drainage pathway of the frontal sinus. The front part of the frontal sinus ostium is surrounded by the frontal beak. The upper part the frontal beak connected to the floor of the frontal sinus. (4) Frontal beak can be used as an landmark of frontal beak approach in the endoscopic frontal sinus surgery. But the lateral view of frontal sinus still was limited in the operation.The endoscopic frontal sinus surgery with the approach of the frontal beak is easy to operate and learn. In this area between the double "L", the operation is safe.

Flexibility method is a commonly used method to determine fracture toughness. In the experiment, it is necessary to prepare specimens with different crack lengths and other exactly same conditions, and carry out a large number of repeated experimental works. Given the above problems, this paper develops a flexibility determination method based on numerical simulation method to calculate the stress intensity factor and fracture toughness of concrete specimens. The results of the test example show that the use of the numerical simulation experiment method is practically feasible and effective to obtain the relation curve between the flexibility C and the crack length a of the concrete specimens and further get the stress strength factor and the fracture toughness under the ultimate load.

This paper examines the relationship between monetary policy and the stock market based on data from two stock indices in China - the Shanghai Composite Index and Shenzhen Composite Index. The result shows only unanticipated monetary policy can affect the stock return significantly. Based on anticipated effects, we examine whether monetary policy has asymmetric effects on the stock market by using a linear model with a dummy variable and a modified Markov–switching model respectively. Our empirical results support existing evidence for developed markets, suggesting that monetary policy has a significant impact on stock returns in bear–market periods, whereas the impact is weak and insignificant in bull–market periods. Given this, we surmise that investor sentiments and borrowing constraints are the main causes of the asymmetric effects found.