Diffusive exit rates through pores in membrane-enclosed structures.

The function of many membrane-enclosed intracellular structures relies on release of diffusing particles that exit through narrow pores or channels in the membrane. The rate of release varies with pore size, density, and length of the channel. We propose a simple approximate model, validated with stochastic simulations, for estimating the effective release rate from cylinders, and other simple-shaped domains, as a function of channel parameters. The results demonstrate that, for very small pores, a low density of channels scattered over the boundary is sufficient to achieve substantial rates of particle release. Furthermore, we show that increasing the length of passive channels will both reduce release rates and lead to a less steep dependence on channel density. Our results are compared to previously-measured local calcium release rates from tubules of the endoplasmic reticulum, providing an estimate of the relevant channel density responsible for the observed calcium efflux.

Fe2O3 Embedded in N-Doped Porous Carbon Derived from Hemin Loaded on Active Carbon for Supercapacitors.

The high power density and long cyclic stability of N-doped carbon make it an attractive material for supercapacitor electrodes. Nevertheless, its low energy density limits its practical application. To solve the above issues, Fe2O3 embedded in N-doped porous carbon (Fe2O3/N-PC) was designed by pyrolyzing Hemin/activated carbon (Hemin/AC) composites. A porous structure allows rapid diffusion of electrons and ions during charge-discharge due to its large surface area and conductive channels. The redox reactions of Fe2O3 particles and N heteroatoms contribute to pseudocapacitance, which greatly enhances the supercapacitive performance. Fe2O3/N-PC showed a superior capacitance of 290.3 F g-1 at 1 A g-1 with 93.1% capacity retention after 10,000 charge-discharge cycles. Eventually, a high energy density of 37.6 Wh kg-1 at a power density of 1.6 kW kg-1 could be delivered with a solid symmetric device.

MRI-visible enlarged perivascular spaces: imaging marker to predict cognitive impairment in older chronic insomnia patients.

OBJECTIVE: Perivascular spaces (PVS), components of the glymphatic system in the brain, have been known to be important conduits for clearing metabolic waste, and this process mainly increases during sleep. Sleep disruption might result in PVS dysfunction and cognitive impairment. In this study, we aim to explore whether MRI-visible enlarged perivascular spaces (EPVS) could be imaging markers to predict cognitive impairment in chronic insomnia patients. METHOD: We obtained data from 156 patients with chronic insomnia and 79 age-matched healthy individuals. Using T2-weighted MRI images, visible EPVS in various brain regions were measured and analyzed. The associations between EPVS numbers and cerebrospinal fluid (CSF) ß-amyloid 42 (Aß42), total tau (t-tau), and phosphorylated tau (p-tau) level in chronic insomnia patients were evaluated. RESULT: Our results showed that MRI-visible EPVS in the frontal cortex, centrum semiovale, basal ganglia, and hippocampus of chronic insomnia patients with impaired cognition (ICG) significantly increased than that in normal cognition (NCG) patients. The increased MRI-visible EPVS in the frontal cortex, centrum semiovale, and basal ganglia were also associated with the increased CSF Aß42, t-tau, and p-tau level in ICG patients. MRI-visible EPVS in the basal ganglia and centrum semiovale had high sensitivity and specificity in distinguishing ICG chronic insomnia patients from those with NCG. CONCLUSION: Our study indicated that MRI-visible EPVS in the basal ganglia and centrum semiovale might be valuable imaging markers to predict cognitive impairment in chronic insomnia patients. It will be meaningful to discern those cognitive decline patients in preclinical stage and take some measures to prevent disease progression. KEY POINTS: • Increased MRI-visible EPVS were associated with the increased CSF Aß42, t-tau, and p-tau level in older chronic insomnia patients with impaired cognition.

Mitotic Functions and Characters of KIF11 in Cancers.

Mitosis mediates the accurate separation of daughter cells, and abnormalities are closely related to cancer progression. KIF11, a member of the kinesin family, plays a vital role in the formation and maintenance of the mitotic spindle. Recently, an increasing quantity of data have demonstrated the upregulated expression of KIF11 in various cancers, promoting the emergence and progression of cancers. This suggests the great potential of KIF11 as a prognostic biomarker and therapeutic target. However, the molecular mechanisms of KIF11 in cancers have not been systematically summarized. Therefore, we first discuss the functions of the protein encoded by KIF11 during mitosis and connect the abnormal expression of KIF11 with its clinical significance. Then, we elucidate the mechanism of KIF11 to promote various hallmarks of cancers. Finally, we provide an overview of KIF11 inhibitors and outline areas for future work.

New Covalent Triazine Framework Rich in Nitrogen and Oxygen as a Host Material for Lithium-Sulfur Batteries.

Lithium-sulfur (Li-S) batteries have been widely considered as the next-generation energy storage system but hindered by the soluble polysulfide intermediate-induced shuttle effect. Doping heteroatoms was confirmed to enhance the affinity of polysulfide and the carbon host, release the shuttle effect, and improve the battery performance. To enhance the Lewis acidity and reinforce the interaction between polysulfide and the carbon skeleton, a novel covalent triazine framework (CTFO) was designed and fabricated by copolymerizing 2,4,6-triphenoxy-s-triazine and 2,4,6-trichloro-1,3,5-triazine through Friedel-Crafts alkylation. Polymerization led to triazine substitution on the para-position of the phenoxy groups of 2,4,6-triphenoxy-triazine and produced two-dimensional three-connected honeycomb nanosheets. These nanosheets were confirmed to exhibit packing in the AB style through the intralayer π-π interaction to form a three-dimensional layered network with micropores of 0.5 nm. The practical and simulated results manifested the enhanced polysulfide capture capability due to the abundant N and O heteroatoms in CTFO. The unique porous polar network endowed CTFO with improved Li-S battery performance with high Coulombic efficiency, rate capability, and cycling stability. The S@CTFO cathode delivered an initial discharge capacity of 791 mAh g-1 at 1C and retained a residual capacity of 512 mAh g-1 after 300 charge-discharge cycles with an attenuation rate of 0.117%. The present results confirmed that multiple heteroatom doping enhances the interaction between the porous polar CTF skeleton and polysulfide intermediates to improve the Li-S battery performance.

The distribution of Mn2+ in rabbit eyes after topical administration for manganese-enhanced MRI.

PURPOSE: To analyze the distribution of Mn(2+) in rabbit eyes after topical administration of Mncl2 for manganese-enhanced MRI. METHODS: Forty-eight Chinese white rabbits were divided into three groups. In group 1 (n = 4), the baseline concentration of Mn(2+) in aqueous, vitreous and serum samples were analyzed. In group 2 and 3, the rabbits received one topical instillation (20 µL) of Mncl2 (1 mol • L(-1)). In group 2 (n = 40), aqueous, vitreous and serum samples were collected and analyzed at predetermined time points (0.5, 1, 2, 4, 6, 12, 24, 48, 72 and 168 hours postdose). Assays were performed using inductively coupled plasma-mass spectrometer (ICP-MS). In group 3 (n = 4), after topical administration of Mncl2, dynamic manganese-enhanced MRI (MEMRI) was performed at predetermined time points. The signal-to-noise ratio (SNR) was calculated to evaluate the enhancements of eyes. RESULTS: After topical administration, the maximum concentrations of Mn(2+) in the aqueous and vitreous samples were 11.1641 ± 0.7202 (2 hours) and 1.5622 ± 0.1567 (12 hours). In group 3, the maximum enhancement of aqueous humor (SNR = 108.81 ± 10.65) appeared at 2 hours postdose, whereas, no significant changes were detected in vitreous. CONCLUSION: Mn(2+) could distribute into aqueous humor rapidly after topical administration of Mncl2, whereas, the concentration of Mn(2+) in vitreous body fluctuated in a narrow range over the course. The uptake of Mn(2+) in retina may involve several different pathways.