Endoplasmic reticulum (ER) is the origin of lipid droplets (LD). Excessive lipid exposure results in ER stress which associates with many diseases. However, the change of the lipid droplet viscosity ...under ER stress is still unrevealed. Hence, it is important to develop a viable tool to investigate the lipid droplet viscosity under ER stress. In this study, a novel viscosity-sensitive fluorescent probe Ru(phen-CA)3Cl2 with long-lived phosphorescence, good spectral stability and large stokes shifts was developed. The probe is prominently located at lipid droplet organelles rather than at lysosome and mitochondria, showing highly sensitive to viscosity. The fluorescence intensity is obviously increased with time under the treatment of dexamethasone and rapamycin. In-vitro and in vivo experiments further confirm that this probe can be used for real-time monitoring the changes of lipid droplet viscosity in response to ER stress. This novel probe provides an effective approach to elucidate the viscosity change in lipid droplets under ER stress.
•We designed the ruthenium complex fluorescent probe targeting lipid droplets.•Ruthenium complex probe has good viscosity response and lipid droplet targeting.•The probe can monitor the changes of lipid droplet viscosity under ER stress.•The viscosity of lipid droplets increased in response to ER stress.
Preferential oxidation of CO (PROX) in H2-rich stream is critical to the production of clean H2 for the H2-based fuel cells, which provide clean and efficient energy conversion. Development of highly ...active and selective PROX catalysts is highly desirable but proved to be extremely challenging. Here we report that CeO2-supported Au single atoms (Au1/CeO2) are highly active, selective, and extremely stable for PROX at the PEMFC working temperature (∼80 °C) with >99.5% CO conversion over a wide temperature window, 70–120 °C (or 50–100 °C, depending on the Au loading). The high CO conversion realized at high temperatures is attributed to the unique property of single-atom catalysts that is unable to dissociatively adsorb H2 and thus has a low reactivity toward H2 oxidation. This strategy is proven in general and can be extended to other oxide-supported Au atoms (e.g., Au1/FeO x ), which may open a new window for the efficient catalysis of the PROX reaction.
In this paper, a 2.5-kW 330-410-V/14-V, 250-kHz dc/dc converter prototype is developed targeted for electric vehicle/hybrid vehicle applications. Benefiting from numerous advantages brought by the ...LLC resonant topology, this converter is able to perform high efficiency, high power density, and low EMI. To arrange high-output current, this paper proposes a parallel-connected LLC structure with developed novel double-loop control to realize an equal current distribution and an overall efficiency improvement. Considering the LLC cell's dimensioning, this paper establishes a more precise model by taking the secondary leakage inductance into consideration. System amelioration and design considerations of the developed LLC are also presented in this paper. A special transformer is presented, and various types of power losses are quantified to improve its efficiency. This converter also implements synchronous rectification, power semiconductor module, and an air-cooling system. The power conversion performance of this prototype is measured and the developed prototype attains a peak efficiency of 95% and efficiency is higher than 94% from 500 W to 2 kW, with a power density of 1 W/cm 3 . Finally, the EMC results of this prototype are also measured and presented.
We consider a point-to-point multiple-input-single-output (MISO) system where a receiver harvests energy from a transmitter. To achieve high-efficiency wireless power transfer (WPT), the transmitter ...performs energy beamforming by using an instantaneous channel state information (CSI). The CSI is estimated at the receiver by training via a preamble and fed back to the transmitter. In this paper, we address the key challenge of balancing the time resource used for channel estimation and WPT to maximize the harvested energy and also investigate the allocation of energy resource used for WPT. First, we consider the general scenario where the preamble length is allowed to vary dynamically depending on channel conditions. The optimal preamble length is obtained online by solving a dynamic programming (DP) problem. The DP problem is proved to reduce to an optimal stopping problem. The optimal policy is then shown to depend only on the channel estimate power. Next, we consider the scenario in which the preamble length is fixed by an offline optimization. Furthermore, we derive the optimal power allocation schemes. For the dynamic-length-preamble scenario, the power is allocated according to both the optimal preamble length and the channel estimate power, while for the fixed-length-preamble scenario, the power is allocated according to only the channel estimate power. By numerical simulations, our results show that with optimal power allocation, the energy harvested by using the optimized fixed-length preamble is close to that harvested by using a dynamic-length preamble, hence allowing a low-complexity yet close-to-optimal WPT system to be implemented in practice.
Electrocatalytic nitrogen oxide reduction (NO x RR) emerges as an effective way to bring the disrupted nitrogen cycle back into balance. However, efficient and selective NO x RR is still challenging ...partly due to the complex reaction mechanism, which is influenced by experimental conditions such as pH and electrode potential. Here, we have studied the enzyme-inspired iron single-atom catalysts (Fe–N4–C) and identified that the selectivity roots in the first step of the nitric oxide reduction. Combining the constrained molecular dynamics (MD) simulations with the quasi-equilibrium approximation, the effects of electrode potential and pH on the reaction free energy were considered explicitly and predicted quantitatively. Systematic heat maps for selectivity between single-N and N–N-coupled products in a wide pH-potential space are further developed, which have reproduced the experimental observations of NO x RR. The approach presented in this study allows for a realistic simulation of the electrocatalytic interfaces and a quantitative evaluation of interfacial effects. Our results in this study provide valuable and straightforward guidance for selective NO x reduction toward desired products by precisely designing the experimental conditions.
Catalysts for CO oxidation reaction are mainly based on oxide/hydroxide materials with multicomponent active sites. Here, we report a nonoxide/hydroxide material, atomically dispersed dual-metal ...single sites (Fe–Co sites) on N-doped carbon support, as a highly active catalyst for CO oxidation. It can greatly lower the temperature for complete CO conversion as low as −73 °C with a turnover frequency of 0.096 s–1. X-ray absorption near-edge structure spectra, pulse-adsorption microcalorimetry, and density functional theory studies show that the Fe–Co sites synergistically catalyze CO oxidation facilely following the Langmuir–Hinshelwood (L-H) mechanism with CO preferentially adsorbing at the Co sites and O2 adsorbing at the Fe sites. These results, for the first time, reveal that the dual-metal single site on N-doped carbon can efficiency catalyze low-temperature CO oxidation reaction without the involvement of supports, such as oxygen vacancies and surface hydroxyl groups.
Pancreatic cancer is currently one of the most lethal diseases. In recent years, increasing evidence has shown that reprogrammed metabolism may play a critical role in the carcinogenesis, ...progression, treatment and prognosis of pancreatic cancer. Affected by internal or external factors, pancreatic cancer cells adopt extensively distinct metabolic processes to meet their demand for growth. Rewired glucose, amino acid and lipid metabolism and metabolic crosstalk within the tumor microenvironment contribute to unlimited pancreatic tumor progression. In addition, the metabolic reprogramming involved in pancreatic cancer resistance is also closely related to chemotherapy, radiotherapy and immunotherapy, and results in a poor prognosis. Reflective of the key role of metabolism, the number of preclinical and clinical trials about metabolism-targeted therapies for pancreatic cancer is increasing. The poor prognosis of pancreatic cancer patients might be largely improved after employing therapies that regulate metabolism. Thus, investigations of metabolism not only benefit the understanding of carcinogenesis and cancer progression but also provide new insights for treatments against pancreatic cancer.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Preparing metal single-atom materials is currently attracting tremendous attention and remains a significant challenge. Herein, we report a novel core–shell strategy to synthesize single-atom ...materials. In this strategy, metal hydroxides or oxides are coated with polymers, followed by high-temperature pyrolysis and acid leaching, metal single atoms are anchored on the inner wall of hollow nitrogen-doped carbon (CN) materials. By changing metal precursors or polymers, we demonstrate the successful synthesis of different metal single atoms dispersed on CN materials (SA-M/CN, M = Fe, Co, Ni, Mn, FeCo, FeNi, etc.). Interestingly, the obtained SA-Fe/CN exhibits much higher catalytic activity for hydroxylation of benzene to phenol than Fe nanoparticles/CN (45% vs 5% benzene conversion). First-principle calculations further reveal that the high reactivity originates from the easier formation of activated oxygen species at the single Fe site. Our methodology provides a convenient route to prepare a variety of metal single-atom materials representing a new class of catalysts.
One neutral tripodal semi-rigidity ligand tri(4-imidazolylphenyl)amine (TIPA) with excellent hole-transfer nature, was selected as a linker to construct MOFs. Two two-dimensional (2D) microporous ...metal–organic frameworks (MOFs) were synthesized solvothermally: Ni(TIPA)(COO−)2(H2O)·2(DMF)2(H2O) (1) and Cd(TIPA)2(ClO4−)2·(DMF)3(H2O) (2). Compound 1 incorporated carboxylic groups into the channel and exhibited the high capacity of light hydrocarbons as well as the remarkable selectivity of C2H2/CH4. The value is in excess of 100 at room temperature, which is the highest value reported to date. Compound 2, as a cationic framework with high water stability, was not only applied as a sensor, displaying the ultrahigh sensitivity against Cr2O72− with a detection limit as low as 8 ppb, but also possessed excellent Cr(vi) sorption with good repeatability in aqueous solution. This study provides an efficient strategy to design cationic MOFs for the selective separation of light hydrocarbons and the sensing and trapping of toxic chromate for the purification of water.
Collinear limit usually provides strong constraints for scattering amplitudes. At strong coupling, collinear limit of the amplitudes in
SYM is related to the large mass limit of the corresponding
Y
...system. In this paper, we consider a special case in which all mass parameters are taken to be large, which corresponds to a multi-double-collinear limit in which a
n
-side polygon becomes pentagons. This limit provides a useful constraint for the amplitudes, in particular can be used to fix the periods part for the case of 4
K
gluons, which is the last missing piece of full amplitudes.
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