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.
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.
•ILCT ligand was applied to construct metal halide cluster-based MOFs.•ILCT ligand affords LPL of the MOFs arising from hybrid charge transfer states.•The heavy atom effect of the metal halide ...cluster promotes LPL enhancement.
The emerging metal–organic frameworks (MOFs) with long persistent luminescence (LPL) have raised particular attention among researchers due to their long-lived triplet states, while most LPL materials facing the problem of low luminescence efficiency. A semiflexible tripodal ligand (1′,1″-(2,4,6-trimethylbenzene-1,3,5-triyl)tris(methylene)tris(pyridin-4(1H)-one), namely TTP) with intra-ligand charge transfer (ILCT) characteristic is selected to form robust LPL MOFs for keeping high luminescence efficiency. Three LPL MOFs named LIFM-130, LIFM-131 and LIFM-132 exhibit highly emissive lime green LPL at ambient conditions with the highest luminescence efficiency of 36 %. It was found that the metal halide clusters in LIFM-130 have salient heavy atom effect (HAE), which can enhance inter- and intramolecular interactions, thus helping LPL emission prominently. Periodic density functional theory (DFT) calculations reveal the participation of heavy atoms affecting luminescence, in which the bright luminescence of MOFs arises from the ligand-center n-π* transition and metal-to-ligand charge transfer, while LIFM-130 has additional emission state of halogen-to-ligand charge transfer. This work illustrates that on the one hand, the construction of CT characterized MOFs is beneficial for the premise of LPL while maintaining high luminescence efficiency. On the other hand, the introduction of metal halide clusters into MOFs can further improve luminescence efficiency and phosphorescence lifetime synergistically by promoting ISC through HAE and reducing non-radiative transitions through the compact structure.
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.
One‐dimensional cylindrical micelles of block copolymers (BCPs) with a crystalline core have many advantages and potential applications. Their properties and performance are tightly related to their ...length. In this review, the growth kinetics and length control of cylindrical crystalline micelles of BCPs are commented. The pathways for formation of crystalline micelles are first introduced, and then the methods for preparing seed micelles (such as sonication and self‐seeding) as well as regulation of the number and crystallinity of the seed micelles are presented. The kinetics for two growth modes starting from the seed micelles, that is, epitaxial growth of unimers onto the seed micelles and end‐to‐end coupling among different micelles, are derived and various factors affecting the growth kinetics and structure of the obtained micelles, including external conditions and BCP structure, are discussed.
There are two modes, that is, epitaxial growth of unimers onto the seed micelles and end‐to‐end coupling of micelles, for growth of one‐dimensional cylindrical micelles of block copolymers, which exhibit different growth kinetics.
Abstract
The Chinese CubeSat Mission, Gamma Ray Integrated Detectors (GRID), recently detected its first gamma-ray burst, GRB 210121A, which was jointly observed by the Gravitational wave high-energy ...Electromagnetic Counterpart All-sky Monitor (GECAM). This burst is confirmed by several other missions, including Fermi and Insight-HXMT. We combined multimission observational data and performed a comprehensive analysis of the burst’s temporal and spectral properties. Our results show that the burst is relatively special in its high peak energy, thermal-like low-energy indices, and large fluence. By putting it to the
E
p
–
E
γ
,iso
relation diagram with assumed distance, we found that this burst can be constrained at the redshift range of 0.3, 3.0. The thermal spectral component is also confirmed by the direct fit of the physical models to the observed spectra. Interestingly, the physical photosphere model also constrained a redshift of
z
∼ 0.3 for this burst, which helps us to identify a host galaxy candidate at such a distance within the location error box. Assuming that the host galaxy is real, we found that the burst can be best explained by the photosphere emission of a typical fireball with an initial radius of
r
0
∼ 3.2 × 10
7
cm.
A polydimethylsiloxane armed with epoxy, alkoxy and acrylate groups was synthesized from silanol terminated-PDMS and epoxy and acrylate groups functionalized silane coupling agents, and utilized as ...the adhesion promoter (AP) to prepare addition-cured liquid silicone rubber that exhibited self-adhesion ability (SA-LSR) with biocompatible thermoplastic polyurethanes (TPU) sheets. The structural characteristics of AP were characterized by Fourier transform infrared (FTIR) spectroscopy, which demonstrated the strong adhesion to polyester-based TPU sheets due to a sufficient amount of acrylate groups, epoxy groups and silanol groups obtained by the hydrolysis of alkoxy groups. In detail, the peel-off strength of SA-LSR and TPU joints reached up to 7.63 N mm
after the optimization of adhesion promoter including type and content, and curing condition including time and temperature. The cohesive failure was achieved during the sample breakage process. Moreover, the SA-LSR showed a good storage stability under proper storage conditions. This design strategy provided the feasibility to combine the advantages of addition-cured liquid silicone rubber and plastics with low melting points, promoting the potential application range of those silicone-based materials.
Abstract
BACKGROUND
Limited data existed to guide the management of intraspinal neurenteric cysts (ISNECs).
OBJECTIVE
To evaluate the risk factors for progression-free survival (PFS), elucidate the ...radiological features of ISNECs, and propose a treatment protocol.
METHODS
From 2003 to 2015, 121 patients with pathologically confirmed ISNECs treated at our institute were included in this study. Pertinent risk factors were evaluated.
RESULTS
Gross total resection (GTR) was achieved in 55 (44.6%) patients; 106 (87.6%), 12 (9.9%), and 3 (2.5%) ISNECs were classified as Wilkins A, B, and C, respectively. After a median follow-up duration of 64.2 mo, recurrence occurred in 25 (22.7%) patients, with a median PFS time of 43.1 mo. The actuarial PFS rates at 5 and 10 yr were 73.2% and 66.2%, respectively. The actuarial overall survival rates at 5 and 10 yr were 100% and 97.6%, respectively. Non-GTR (hazard ratio HR, 5.836; 95% confidence interval CI, 1.698-20.058; P = .005), Wilkins B/C (HR, 3.129; 95% CI, 1.009-9.702; P = .048), and a history of surgical resection (HR, 3.690; 95% CI, 1.536-8.864; P = .004) were adverse factors.
CONCLUSION
GTR and Wilkins A were favorable factors for PFS. If tolerable, GTR alone was advocated as an optimal treatment. Because of the benign nature and favorable prognosis, non-GTR was an alternative if GTR failed. Close follow-up was needed because of the recurrent tendency of ISNEC. Future study with a large cohort is necessary to verify our findings.
A series of liquid crystalline/crystalline block copolymers (BCPs) containing poly(methacrylate) block with liquid crystalline (LC) azobenzene moieties in the side chains (PMMAzo) and crystalline ...block poly(l-lactide) (PLLA) were prepared. The interplay of microphase separation, crystallization and LC ordering in these BCPs was investigated. It is revealed that microphase separation between two blocks is favorable to the LC ordering, which is attributed to the enhanced local concentration of LC moieties in PMMAzo microdomains. For a similar reason, crystallization of PLLA can intensify microphase separation thus facilitate LC ordering of PMMAzo. PLLA crystallization may also stabilize the LC structure, leading to phase transition temperatures of the BCPs higher than that of PMMAzo homopolymer. On the other hand, the LC ordering can conversely affect crystallization of PLLA. The crystallizability of PLLA is weakened by the chemically linked PMMAzo block. The special PLLA ε-crystals, which are usually formed in the presence of organic solvents, are unexpectedly observed under suitable conditions.
Display omitted
•A series of crystalline/liquid crystalline block copolymers (PMMAzo-b-PLLA) with well-defined structure were synthesized.•The interplay of microphase separation, crystallization and LC ordering in these crystalline/LC BCPs were investigated.•PLLA crystallization can stabilize the liquid crystalline structure, leading to an enhanced LC ordering.•Under suitable conditions, the LC ordering can induce formation of PLLA ε-crystals in the bulk.
PDF
