Optimal Investment with Multiple Risky Assets for an Insurer in an Incomplete Market

This paper studies the optimal investment problem for an insurer in an incomplete market. The insurer's risk process is modeled by a Lévy process and the insurer is supposed to have the option of investing in multiple risky assets whose price processes are described by the standard Black-Scholes model. The insurer aims to maximize the expected utility of terminal wealth. After the market is completed, we obtain the optimal strategies for quadratic utility and constant absolute risk aversion (CARA) utility explicitly via the martingale approach. Finally, computational results are presented for given raw market data

Optimization of the control performance of a novel 3/2 water proportional directional valve with a special position following servo mechanism

The 3/2 water proportional directional valve (PDV) is an important hydraulic component to ensure a precise, low impact, and safety control of hydraulic powered roof support, which has been a technical challenge facing to coal mining industry for many years. To address this issue, a new 3/2 water PDV is developed. The valve includes a novel three-core follow-up servo mechanism consisting of three key components: the pilot inlet valve, the pilot outlet valve, and the main inlet spool. This mechanism enables precise and reliable opening, and closing capacity of the valve. The prototype is manufactured and the performance test is conducted to improve the control performance of the new water PDV. During the test, two significant discoveries are made. First, it is determined that the control chamber of the main inlet spool must be in the predischarge state at the initial time to ensure adequate closing capacity of the new valve during the returning process. Second, it is found that the continuous small-step control mode can better cope with the friction and is more effective in achieving quick and smooth following characteristics of the three valve cores in the opening process, compared with the ramp control mode

The design and impact of in-situ and operando thermal sensing for smart energy storage

Lithium-ion is increasingly the technology of choice for battery-powered systems. Current cell performance monitoring, which relies on measurements of full cell voltage and sporadic surface temperature, does not provide a reliable information on the true internal battery state. Here, we address this issue by transforming off the shelf cells into smart systems by embedding flexible distributed sensors for long-term in-situ and operando thermodynamic data collection. Our approach, which enables the monitoring of the true battery state, does not impact its performance. In particular, our results show that this unprecedented methodology can be used to optimise the performance and map the safety limits of lithium-ion cells. We find that the cell core temperature is consistently and significantly higher than the surface temperature, and reveal a breach of safety limits during a rapid discharge test. We also demonstrate an application of a current considerably higher than the manufacturers’ specification, enabling a significant decrease in charging time, without compromising the cell’s thermal stability. Consequently, this work on cell instrumentation methodology has the potential to facilitate significant advances in battery technology

Strength damage analysis on cement-and-fly ash treated organic soils subjected to freeze-thaw cycles.7z

Organic soil is usually required to be improved/treated before engineering construction, especially in cold regions. In this study, cement and fly ash are adopted as additives to stabilize the organic soil. A photogrammetric method is proposed to accurately reconstruct the surface of these cement-and-fly ash treated organic soils, and measure the volume before and after freeze thaw cycles (F-T-C). Meantime, unconfined compression (U-C) test was performed to evaluate the performance of these specimens after different numbers of F-T-C, and the influence of organic content on specimens behavior also was investigated. These results indicated that an increase in the cement content enhanced the resistance of the organic soils against volume change before and after F-T-C. The adoption of cement and fly ash at proper contents significantly improve the unconfined compression strength (UCS) of organic soils subjected to different number of F-T-C. The 15% organic matter content is an important boundary for reflecting the engineering properties of treated organic soil. A stress-strain curve prediction model was established with consideration of the number of F-T-C and volumetric change after the F-T-C.</p

Synthesis and Characterization of Constrained Geometry Oxygen and Sulphur Functionalized Cyclopentadienylchromium Complexes and Their Use in Catalysis for Olefin Polymerization

A series of constrained geometry O-functionalized cyclopentadienylchromium complexes (1–6) and a S-functionalized cyclopentadienylchromium complex (7) were first synthesized, characterized, and tested as catalyst precursors for the olefin polymerization. In the presence of MAO, the complexes exhibited high catalytic activity for the polymerization of ethylene. It is shown that ligand variations can have a substantial effect on catalyst activity and stability. The effect of Al/Cr ratio on catalytic activity was also studied

Contribution of Arbuscular Mycorrhizal Fungal Communities to Soil Carbon Accumulation during the Development of Cunninghamia lanceolata Plantations

Arbuscular mycorrhizal (AM) fungi can establish mutual association with most land plants, and impact a series of important ecological processes, including plant productivity, ecological succession and soil carbon (C) accumulation. Understanding the AM fungal diversity and community assembly, and their associated soil C sequestration, could be a crucial interest for the forest ecologist. In this study, the AM fungal abundances and community structure as well as glomalin-related soil protein (GRSP) concentrations were investigated in typical development stages (young, middle and mature) of Cunninghamia lanceolate plantations, which are widely distributed species in subtropical regions. The mycorrhizal colonization, spore density, AM fungal biomass and diversity were higher in mature than younger stands. The development of C. lanceolata also increased soil GRSP concentrations, and enhanced their C contribution to soil organic C. Soil difficulty extractable (DE) GRSP demonstrated a greater C contribution to soil organic C relative to easily extractable (EE) GRSP. Linkage analyses found that AM fungal biomass demonstrated a positive correlation with GRSP concentrations, and soil organic C positively related to DE-GRSP and total (T) GRSP. Soil AM fungal community structure differed dramatically across all studied C. lanceolata plantations with a decrease in Gigasporaceae and increase in Acaulosporaceae. Soil AM fungal community assembly was more phylogenetic clustering than expected by chance and primarily shaped by deterministic processes, with a non-shift during the development of C. lanceolata. Collectively, C. lanceolata development shaped the AM fungal communities and enhanced their biomass and GRSP contents, which might, in turn, partially contribute to soil C accumulation

Contribution of Arbuscular Mycorrhizal Fungal Communities to Soil Carbon Accumulation during the Development of <i>Cunninghamia lanceolata</i> Plantations

Arbuscular mycorrhizal (AM) fungi can establish mutual association with most land plants, and impact a series of important ecological processes, including plant productivity, ecological succession and soil carbon (C) accumulation. Understanding the AM fungal diversity and community assembly, and their associated soil C sequestration, could be a crucial interest for the forest ecologist. In this study, the AM fungal abundances and community structure as well as glomalin-related soil protein (GRSP) concentrations were investigated in typical development stages (young, middle and mature) of Cunninghamia lanceolate plantations, which are widely distributed species in subtropical regions. The mycorrhizal colonization, spore density, AM fungal biomass and diversity were higher in mature than younger stands. The development of C. lanceolata also increased soil GRSP concentrations, and enhanced their C contribution to soil organic C. Soil difficulty extractable (DE) GRSP demonstrated a greater C contribution to soil organic C relative to easily extractable (EE) GRSP. Linkage analyses found that AM fungal biomass demonstrated a positive correlation with GRSP concentrations, and soil organic C positively related to DE-GRSP and total (T) GRSP. Soil AM fungal community structure differed dramatically across all studied C. lanceolata plantations with a decrease in Gigasporaceae and increase in Acaulosporaceae. Soil AM fungal community assembly was more phylogenetic clustering than expected by chance and primarily shaped by deterministic processes, with a non-shift during the development of C. lanceolata. Collectively, C. lanceolata development shaped the AM fungal communities and enhanced their biomass and GRSP contents, which might, in turn, partially contribute to soil C accumulation

Kinetic, Isotherm, and Thermodynamic Studies for Ag(I) Adsorption Using Carboxymethyl Functionalized Poly(glycidyl methacrylate)

Industrial wastewater contains large amounts of silver ions. Here, a new adsorbent was synthesized by functionalizing poly(glycidyl methacrylate) with carboxymethyl groups. The adsorbent was used to recover Ag(I) in wastewater. Fourier transform infrared spectroscopy, zeta potential, scanning electron microscopy, and X-ray photoelectron spectroscopy were used to characterize the adsorbent. The experimental parameters affecting the adsorption are solution pH, contact time, and initial silver ion concentration. The optimum pH for adsorption of Ag(I) is pH 4. The maximum adsorption capacity at pH 4 is 157.05 mg/g, and the adsorption reaches equilibrium at 300 min. The kinetics and isotherms of the adsorption process were described by pseudo second-order, Langmuir and D-R models, respectively. The adsorption process was a single layer chemical adsorption, exothermic, feasible, and spontaneous. The adsorption mechanism is electrostatic or chelation. The adsorbent selectively absorbed Ag(I) from coexisting ions (Cu2+, Ni2+, Co2+, Zn2+). Finally, the removal rate of silver ions decreased from 79.29% to 65.01% after four repetitive experiments, which proved that the adsorbent had good reusability. The adsorbent has great potential benefit in removing Ag(I)

MicroRNA-133a and Myocardial Infarction

Myocardial infarction (MI) is the leading cause of morbidity and mortality in the world. The infarcted heart displays typical cell death cascades characterized by a loss of cells and fibrotic scarring in the myocardium. Cardiac hypertrophy and fibrosis largely contribute to ventricular wall thickening and stiffening, altogether defining an adverse cardiac remodeling that ultimately leads to impaired cardiac function and subsequent heart failure. Finding a strategy to promote therapeutic, instead of detrimental, cardiac remodeling may pose as a potent MI treatment. Accumulating evidence shows that microRNAs (miRNAs) may play an essential role in cardiovascular diseases. In particular, microRNA-133a (miR-133a) is one of the most abundant miRNAs in the heart. Multiple studies have demonstrated that miR-133a participates in the early pathology of MI, as well as in subsequent cardiac remodeling. In this review, we summarize recent research progress highlighting the regulatory effects of miR-133a in ischemic myocardial diseases, such as inhibiting angiogenesis, apoptosis, fibrosis, hypertrophy, and inflammation, while promoting therapeutic cardiac remodeling. The goal is to elicit a critical discussion on the translational direction of miRNA-mediated treatments towards a safe and effective MI therapy