This study investigates the optimization problem of an infinite stage discrete time Markov decision process (MDP) with a long‐run average metric considering both mean and variance of rewards ...together. Such performance metric is important since the mean indicates average returns and the variance indicates risk or fairness. However, the variance metric couples the rewards at all stages, the traditional dynamic programming is inapplicable as the principle of time consistency fails. We study this problem from a new perspective called the sensitivity‐based optimization theory. A performance difference formula is derived and it can quantify the difference of the mean‐variance combined metrics of MDPs under any two different policies. The difference formula can be utilized to generate new policies with strictly improved mean‐variance performance. A necessary condition of the optimal policy and the optimality of deterministic policies are derived. We further develop an iterative algorithm with a form of policy iteration, which is proved to converge to local optima both in the mixed and randomized policy space. Specially, when the mean reward is constant in policies, the algorithm is guaranteed to converge to the global optimum. Finally, we apply our approach to study the fluctuation reduction of wind power in an energy storage system, which demonstrates the potential applicability of our optimization method.
Highlights ► We successfully prepared hyaluronic acid coated, paclitaxel loaded, nanostructured lipid carriers (HA-NLCs) via electrostatic attraction. ► The in vitro cytotoxicity of HA-NLCs was ...superior to that of Taxol® in B16, CT26 and HCT116 cell lines. ► The in vivo antitumor effect of HA-NLCs in B16-bearing Kunming mice was extremely promising. ► HA-NLC prepared via electrostatic attraction was an effective carrier for delivering paclitaxel PTX to tumors overexpressing CD44.
Sulfenylation of C–H bonds for C–S bond formation under metal‐free conditions has become established as a powerful tool in organic chemistry. Various sulfenylation reagents such as thiols, ...disulfides, sulfinic acids, and so on have been employed for sulfenynlation reactions. In this review we mainly summarize the recent advances (2014 to the present) in this area and also discuss the mechanisms.
Sulfenylation of C–H bonds has recently come to receive more and more attention. In this Microreview, recent advances in sulfenylation of C–H bonds for C–S bond formation under metal‐free conditions are reviewed.
As one of the important probes of chemical bonding, planar tetracoordinate carbon (ptC) compounds have been receiving much attention. Compared with ptC clusters, the heavier planar tetracoordinate ...silicon, germanium, tin, lead (ptSi/Ge/Sn/Pb) systems are scarcer and more exotic. The 18-valence-electron (ve)-counting is one important guide, though not the only rule, for the design of planar tetra-, penta-coordinate carbon and silicon clusters. The 18ve ptSi/Ge system is very scarce and needs to be expanded. Based on the isoelectronic principle and bonding similarity between the Al atom and the BeH unit, inspired by the previously reported ptSi global minimum (GM) SiAl42−, a series of ternary 18 ve XBe4H5− (X = Si, Ge, Sn, Pb) clusters were predicted with the ptSi/Ge/Sn/Pb centers. Extensive density functional theory (DFT) global minimum searches and high-level CCSD(T) calculations performed herein indicated that these ptSi/Ge/Sn/Pb XBe4H5− (X = Si, Ge, Sn, Pb) clusters were all true GMs on their potential energy surfaces. These GMs of XBe4H5− (X = Si, Ge, Sn, Pb) species possessed the beautiful fan-shaped structures: XBe4 unit can be stabilized by three peripheries bridging H and two terminal H atoms. It should be noted that XBe4H5− (X = Si, Ge, Sn, Pb) were the first ternary 18 ve ptSi/Ge/Sn/Pb species. The natural bond orbital (NBO), canonical molecular orbitals (CMOs) and adaptive natural densitpartitioning (AdNDP) analyses indicated that 18ve are ideal for these ptX clusters: delocalized one π and three σ bonds for the XBe4 core, three Be-H-Be 3c-2e and two Be-H σ bonds for the periphery. Additionally, 2π plus 6σ double aromaticity was found to be crucial for the stability of the ptX XBe4H5− (X = Si, Ge, Sn, Pb) clusters. The simulated photoelectron spectra of XBe4H5− (X = Si, Ge, Sn, Pb) clusters will provide theoretical basis for further experimental characterization.
Photothermal therapy (PTT) is one of the most promising approaches to combat multidrug‐resistant bacteria with less potential to induce resistance and systemic toxicity. However, uncontrollable ...distribution of photothermal agents leads to lethal temperatures for normal cells, and failure to offer timely and effective antibacterial stewardship. A pH switchable nanoplatform for persistent luminescence imaging‐guided precise PTT to selectively destroy only pathological cells while protecting nearby normal cells in bacterial infected microenvironment is shown. The PLNP@PANI‐GCS is fabricated by grafting polyaniline (PANI) and glycol chitosan (GCS) onto the surface of persistent luminescence nanoparticles (PLNPs). It takes advantage of the long persistent luminescence of PLNPs to realize autofluorescence‐free imaging, the pH‐dependent light–heat conversion property of PANI to get a stronger photothermal effect at pH 6.5 than pH 7.4, and the pH environment responsive surface charge transition of GCS. Consequently, PLNP@PANI‐GCS enables effective response to bacterial‐infected acid region and electrostatic bonding to bacteria in vivo, ensuring the spatial accuracy of near‐infrared light irradiation and specific heating directly to bacteria. In vivo imaging‐guided PTT to bacterial infection abscess shows effective treatment. PLNP@PANI‐GCS has great potential in treating multidrug‐resistant bacterial infection with low possibility of developing microbial drug resistance and little harm to normal cells.
A pH switchable nanoplatform is developed for in vivo persistent luminescent imaging and precise photothermal therapy of bacterial infections. This nanoplatform exhibits specific photothermal therapy to acidic bacterial‐infected regions but no damage to normal tissues.
Based on previous studies about microflora regulation and immunity enhancement activities of polysaccharides from
Nannf. var.
(Nannf.) L. T. Shen (CPP), there is little study on intestinal mucosal ...immunity, which is a possible medium for contacting microflora and immunity. In the present study, the BALB/c mice were divided into five groups (eight mice in each group), including a normal group (Con), a model control group (Model), and model groups that were administered CPP (50, 100, 200 mg/kg/d) orally each day for seven days after intraperitoneal injection of 60 mg/kg BW/d cyclophosphamide (CP) for three days. CPP recovered the spleen index and restored the levels of IFN-γ, IL-2, IL-10, as well as serum IgG. In addition, it elevated ileum secretory immunoglobulin A (sIgA), the number of
and acetic acid content in cecum. These results indicated that CPP plays an important role in the protection against immunosuppression, especially mucosa immune damage, and the inhibition of pathogenic bacteria colonization, which could be considered a potential natural source of immunoregulator.
Hepatocellular carcinoma (HCC) is the sixth-most common malignancy worldwide. Multiple previous studies have assessed the relationship between TM6SF2 gene polymorphism and the risk of developing HCC, ...with discrepant conclusions reached. To assess the association of TM6SF2 rs58542926 T/C gene polymorphism with liver cancer, we performed the current meta-analysis.
This study queried the MEDLINE, PubMed, EMBASE, and CENTRAL databases from inception to April 2019. Case-control studies assessing the relationship between TM6SF2 rs5854292 locus polymorphism and liver cancer were selected according to inclusion and exclusion criteria. The Stata 12.0 software was employed for data analysis.
A total of 5 articles, encompassing 6873 patients, met inclusion criteria and were included in the meta-analysis. Statistical analysis showed that the TM6SF2 gene polymorphism was significantly associated with liver cancer in the allele contrast, dominant, recessive and over dominant models (T vs C, OR = 1.621, 95%CI 1.379-1.905; CT + TT vs CC. OR = 1.541, 95%CI 1.351-1.758; TT vs CT + CC, OR = 2.897, 95%CI 1.690-4.966; CC + TT vs TC, OR = 0.693, 95%CI 0.576-0.834). The Egger's test revealed no significant publication bias.
The present findings suggest a significant association of TM6SF2 gene polymorphism with HCC risk in the entire population studied.
Hard carbon attracts considerable attention as an anode material for sodium‐ion batteries; however, their poor rate capability and low realistic capacity have motivated intense research effort toward ...exploiting nanostructured carbons in order to boost their comprehensive performance. Ultramicropores are considered essential for attaining high‐rate capacity as well as initial Coulombic efficiency by allowing the rapid diffusion of Na+ and inhibiting the contact of the electrolyte with the inner carbon surfaces. Herein, hard carbon nanosheets with centralized ultramicropores (≈0.5 nm) and easily accessible carbonyl groups (CO)/hydroxy groups (OH) are synthesized via interfacial assembly and carbonization strategies, delivering a large capacity (318 mA h g−1 at 0.02 A g−1), superior rate capability (145 mA h g−1 at 5.00 A g−1), and approximately 95% of reversible capacity below 1.00 V. Notably, a new charge model favoring fast capacitive sodium storage with dual potential plateaus is proposed. That is, the deintercalation of Na+ from graphitic layers is manifested as the low‐potential plateau region (0.01−0.10 V), contributing to stable insertion capacity; meanwhile, the surface desodiation process of the CO and OH groups corresponds to the high‐potential plateau region (0.40−0.70 V), contributing to a fast capacitive storage.
Hard carbon nanosheets with centralized ultramicropores (≈0.5 nm), accessible functional CO/OH groups, and large graphitic layer spacings exhibit excellent sodium‐storage properties. The desodiation process from graphitic layers and CO/OH groups results in a new sodium‐storage characteristic with dual‐potential plateaus during the charge process, which favors a high output of 95%, realistic capacity, and rapidly capacitive sodium storage.
Here, N- and P-doped carbon–carbon nanotube CoP (NPC-CNTs-CoP) nanoparticles dodecahedra are achieved by multistep calcination of the Zn-doped zeolitic imidazolate framework ZIF-67 precursor ...(ZnCo-ZIF). In the structures, the presence of N and P atoms, abundant CNTs and the CoP nanoparticles can enhance electrochemical activity and promote the structural stability of materials. As the temperature increases, the Zn contents gradually reduce to zero, which provides more active sites for electrochemical testing. Furthermore, the high specific surface area and microporous behavior of NPC-CNTs-CoP-9 make it excellent in electrocatalytic testing. NPC-CNTs-CoP-9 shows a low overpotential of 224 mV at 10 mA·cm
−2
in 1.0 mol·L
−1
KOH solution. The strategy of zeolitic imidazole framework-derived transition metal phosphides will provide a new sight for developing energy conversion materials.
In the present work, Bi3+ was used to substitute for Nd3+ in the NdNbO4 ceramic and pure fergusonite solid solution was formed within 20 mol. % substitutions. Microwave dielectric permittivity of the ...(Nd1‐xBix)NbO4 (x ≤ 0.2) ceramics increased linearly with x value due to the larger ionic polarizability of Bi3+ than Nd3+. Excellent microwave dielectric properties with a permittivity (εr) ~22.5, a Qf (Q = quality factor, f = resonant frequency) ~50 000 GHz, and a TCF ~−9 ppm/°C were obtained in the (Nd0.9Bi0.1)NbO4 ceramic. This method might work in other fergusonite‐type rare‐earth ortho‐niobates.
Temperature coefficient of NdNbO4 microwave ceramic was adjusted to near zero by Bi substitutions.
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