For the bulk self-assembly of traditional diblock copolymers (di-BCPs), lamellar structures only occur when two constituents have similar volume fractions (
) and two alternating layers tend to have ...similar thicknesses. Highly asymmetric lamellar (A-LAM) structures, in which the thickness of one layer is several times higher than the other, are hardly formed in di-BCPs, while they have potential applications in nanolithography. In this work, A-LAM structures with different dimensions were constructed using a type of simple linear di-BCP, polystyrene-
-poly(4-vinylpyridine)propane-1-sulfonate (PS-
-PVPS) with the polyzwitterionic block PVPS in minority. The origin of the A-LAM structure was ascribed to the electrostatic crosslinking and confirmed by doping PS-
-PVPS block copolymers (BCPs) with
-butyl pyridinium methane sulfonate (BPMS). The morphology of compositionally asymmetric PS-
-PVPS BCPs changed from A-LAM to cylindrical structures upon salt-doping,
the phase behavior of common BCPs was recovered. In addition, the morphologies of PS-
-PVPS BCPs with similar molecular weights but varied compositions were also studied, and only two kinds of structures (lamellar or ill-defined spherical structure) were observed when the volume fraction of PVPS (
) was less than 0.5, and the composition range for the formation of the lamellar structure was found to be
≥ 0.188.
Norfloxacin (NOR) is applied clinically to treat keratitis. However, NOR has brought severe side-effects for human corneal epithelium (HCEP) due to overdose and potential toxicity. In this study, two ...in vitro experimental models including monolayer HCEP cells and tissue-engineered human corneal epithelium (TE-HCEP) were used to explore the cytotoxicity and its related mechanisms. The HCEP cells treated with NOR at concentrations from 0.1875 to 3.0 mg/mL displayed abnormal morphology, declined viability, and increased plasma membrane permeability. Moreover, 0.75 mg/mL NOR induced chromatin condensation, S phase arrest, phosphatidylserine externalization, and formation of apoptotic body through activation of caspase-2/−8/−9/−3, downregulation of Bcl-2 and Bcl-xL, upregulation of Bad and Bax, mitochondrial transmembrane potential disruption and release of cytochrome c and apoptosis inducing factor into cytosol, whereas 1.5 mg/mL and 3.0 mg/mL NOR upregulated the expressions of receptor-interacting protein kinase 1 (RIPK1), RIPK3 and mixed lineage kinase domain-like (MLKL) together with inactivation of caspase-2/−8. Furthermore, 0.1875–3.0 mg/mL NOR destroyed the multilayer structure of TE-HCEP model due to a dose-dependent cytotoxicity, which validated the above results. Overall, low-dose (0.1875–0.75 mg/mL) NOR induced apoptosis through mitochondrion-dependent and death receptor-mediated pathways, and high-dose (1.5–3.0 mg/mL) NOR triggered necroptosis via RIPK1-RIPK3-MLKL cascade in HCEP cells.
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•Norfloxacin (NOR) showed dose- and time-dependent cytotoxic effects on human corneal epithelial cells.•Low-dose (0.1875-0.75 mg/mL) NOR induced apoptosis through mitochondrion-dependent and death receptor-mediated pathways.•High-dose (1.5-3.0 mg/mL) NOR triggered necroptosis via RIPK1-RIPK3-MLKL cascade.
Block copolymer single crystals (BCPSCs) have attracted widespread attentions due to their unique two‐dimensional (2D) structure, good controllability, and great potential applications in recent ...years. In this paper, the morphology, surface structure of BCPSCs and the related influencing factors are reviewed. We also summarize the studies of 2D crystalline assemblies of block copolymers (BCPs) driven by crystallization and intermolecular π–π interaction. Moreover, the functionalization and properties of BCPSCs and 2D crystalline assemblies of BCPs are introduced. Finally, we put forward some unsolved problems in this field.
The strong adhesion of thermally conductive silicone encapsulants on highly integrated electronic devices can avoid external damages and lead to an improved long-term reliability, which is critical ...for their commercial application. However, due to their low surface energy and chemical reactivity, the self-adhesive ability of silicone encapsulants to substrates need to be explored further. Here, we developed epoxy and alkoxy groups-bifunctionalized tetramethylcyclotetrasiloxane (D4H-MSEP) and boron-modified polydimethylsiloxane (PDMS-B), which were synthesized and utilized as synergistic adhesion promoters to provide two-component addition-cured liquid silicone rubber (LSR) with a good self-adhesion ability for applications in electronic packaging at moderate temperatures. The chemical structures of D4H-MSEP and PDMS-B were characterized by Fourier transform infrared spectroscopy. The mass percentage of PDMS-B to D4H-MSEP, the adhesion promoters content and the curing temperature on the adhesion strength of LSR towards substrates were systematically investigated. In detail, the LSR with 2.0 wt% D4H-MSEP and 0.6 wt% PDMS-B exhibited a lap-shear strength of 1.12 MPa towards Al plates when curing at 80 °C, and the cohesive failure was also observed. The LSR presented a thermal conductivity of 1.59 W m−1 K−1 and good fluidity, which provided a sufficient heat dissipation ability and fluidity for potting applications with 85.7 wt% loading of spherical α-Al2O3. Importantly, 85 °C and 85% relative humidity durability testing demonstrated LSR with a good encapsulation capacity in long-term processes. This strategy endows LSR with a good self-adhesive ability at moderate temperatures, making it a promising material requiring long-term reliability in the encapsulation of temperature-sensitive electronic devices.
Adult neurogenesis plays a vital role in maintaining cognitive functions in mammals and human beings. Mobilization of hippocampal neurogenesis has been regarded as a promising therapeutic approach to ...restore injured neurons in neurodegenerative diseases including Alzheimer's disease (AD). Icarisid II (ICS II), an active ingredient derived from Epimedii Folium, has been reported to exhibit multiple neuroprotective effects. In the present study, we investigated the effects of ICS II on the proliferation and differentiation of neural stem cells (NSCs) and amyloid precusor protein (APP)‐overexpressing NSCs (APP‐NSCs) in vitro. Our results demonstrated that ICS II dose‐dependently suppressed apoptosis and elevated viability of APP‐NSCs. ICS II (1 μM) potently promoted proliferation and neuronal differentiation of NSCs and APP‐NSCs. ICS II (1 μM) significantly upregulated Wnt‐3a expression, increased the phosphorylation of glycogen synthase kinase‐3β and enhanced the nuclear transfer of β‐catenin. Moreover, ICS II also promoted astrocytes to secrete Wnt‐3a, which positively modulates Wnt/β‐catenin signaling pathway. These findings demonstrate that ICS II promotes NSCs proliferation and neuronal differentiation partly by activating the Wnt/β‐catenin signaling pathway.
Diclofenac sodium (DFS), a nonsteroidal anti-inflammatory drug, is frequently used in ophthalmology, but it causes negative effects on corneas. The mechanisms underlying the toxicities to corneas ...remains unclear. The present study was designed to assess the cytotoxicity of DFS to human corneal epithelial (HCEP) cells in vitro and further investigate its related mechanisms. The HCEP cells were treated with DFS at different concentrations ranging from 0.003 125% to 0.1%. DFS showed a dose- and time-dependent cytotoxicity to HCEP cells including abnormal morphology and declined viability. The 0.05% DFS-treated HCEP cells presented cell cycle arrest at S phase, reactive oxygen species (ROS) overproduction, and positive staining of phosphorylated H2AX, suggesting that DFS caused ROS-mediated DNA damage. The upregulation of p53 expression, formation of apoptotic body, phosphatidylserine externalization, and DNA ladder demonstrated that the p53-dependent apoptosis pathway was involved in the cytotoxicity of DFS. Furthermore, DFS activated caspase-8, caspase-9, and caspase-3 altered the expression levels of Bcl-2 family proteins including tBid, Bax, and Bcl-2, as well as increased poly(ADP-ribose) polymerase (PARP) cleavage. DFS also induced ΔΨm disruption, resulting in the release of cytochrome c and apoptosis-inducing factor into the cytoplasm. Additionally, the DFS-induced apoptosis was alleviated by p53 inhibitor. Taken together, DFS triggered p53-dependent apoptosis in HCEP cells via ROS-mediated crosstalk between the extrinsic and intrinsic pathways.
Due to their low cost and high efficiency, polymer/nanocrystal hybrid solar cells (HSCs) have attracted much attention in recent years. In this work, water-soluble hybrid materials consisting of ...amphiphilic block copolymers (ABCPs) and cadmium telluride nanocrystals (CdTe NCs) were used as the active layer to fabricate the HSCs via aqueous processing. The ABCPs composed of poly(3-hexylthiophene) (P3HT) and poly(acrylic acid) (PAA) self-assembled into ordered nanostructured micelles which then transformed to nanowires by comicellization with P3HT additives. Furthermore, after annealing, the hybrid materials formed an interpenetrating network which resulted in a maximum power conversion efficiency of 4.8% in the HSCs. The properties of the hybrid materials and the film morphology were studied and correlated to the device performance. The results illustrate how the inclusion of ABCPs for directed assembly and homo-P3HT for charge transport and light absorption improves device performance. The aqueous-processed HSCs based on the ABCPs and NCs offer an effective method for the fabrication of efficient solar cells.
Poly(vinylidene difluoride)/organically modified montmorillonite (PVDF/OMMT) composite nanofibers were prepared by electrospinning the solution of PVDF/OMMT precursor in DMF. Wide-angle X-ray ...diffraction (WAXD) and transmission electron microscopy (TEM) show that in the bulk of the PVDF/OMMT precursor OMMT platelets are homogeneously dispersed in PVDF and can be both intercalated and exfoliated. It is found that the diameter of the PVDF/OMMT composite nanofibers is smaller than that of the neat PVDF fibers because the lower viscosity of PVDF/OMMT solution, which is attributed to the possible adsorption of PVDF chains on OMMT layers and thus reduction in number of entanglement. The crystal structure of the composite nanofibers was investigated using WAXD and Fourier transform infrared (FT-IR) and compared with that of thin film samples. The results show that the nonpolar α phase is completely absent in the electrospun PVDF/OMMT composite nanofibers, whereas it is still present in the neat PVDF electrospun fibers and in the thin films of PVDF/OMMT nanocomposites. The cooperative effect between electrospinning and nanoclay on formation of polar β and γ crystalline phases in PVDF is discussed. The IR result reveals that electrospinning induces formation of long trans conformation, whereas OMMT platelets can retard relaxation of PVDF chains and stabilize such conformation due to the possible interaction between the PVDF chains and OMMT layers. This cooperative effect leads to extinction of nonpolar α phase and enhances the polar β and γ phases in the electrospun PVDF/OMMT composite nanofibers.
Brain abscesses, a severe infectious disease of the CNS, are usually caused by a variety of different pathogens, which include Streptococcus intermedius (S. intermedius). Pulmonary arteriovenous ...fistulas (PAVFs), characterized by abnormal direct communication between pulmonary artery and vein, are a rare underlying cause of brain abscesses.
The patient was a previous healthy 55-year-old man who presented with 5 days of headache and fever. Cerebral magnetic resonance imaging (MRI) suggested a brain abscess. Thoracic CT scan and angiography demonstrated PAVFs. Aiding by metagenomic next-generation sequencing (mNGS) of the cerebrospinal fluid (CSF) sample which identified S. intermedius as the causative pathogen, the patient was switched to the single therapy of large dose of penicillin G and was cured precisely and economically.
It is an alternative way to perform mNGS to identify causative pathogens in patients with brain abscesses especially when the results of traditional bacterial culture were negative. Further thoracic CT or pulmonary angiography should also be undertaken to rule out PAVFs as the potential cause of brain abscess if the patient without any known premorbid history.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
In this work, the advanced all solid-state block copolymer electrolytes (SBCPEs) for lithium-ion batteries with double conductive phases, poly(ethylene oxide)-
-poly(trimethyl-
...-((2-(dimethylamino)ethyl methacrylate)-7-propyl)-ammonium bis(trifluoromethanesulfonyl) imide) (PEO-
-PDM-dTFSI)/LiTFSI, were fabricated, in which the charged PDM-dTFSI block contained double quaternary ammonium cations and the PEO block was doped with LiTFSI. The disordered (DIS) and ordered lamellae (LAM) phase structures were achieved by adjusting the composition of the block copolymer and the doping ratio
. In addition, the presence of the hard PDM-dTFSI block and the formation of the LAM phase structure resulted in a good mechanical strength of the solid PEO-
-PDM-dTFSI/LiTFSI electrolyte, and it could maintain a high level of 10
Pa at 100 °C, which was around 10,000 times stronger than that of the PEO/LiTFSI electrolyte. Based on the good mechanical and electrochemical properties, the PEO-
-PDM-dTFSI/LiTFSI SBCPE exhibited excellent long-term galvanostatic cycle performance, indicating the strong ability to suppress lithium dendrites.
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