•Engaging in CSR activities can increase stock returns of hospitality firms during the COVID-19 pandemic.•The positive effect of CSR on stock returns takes place in five days.•Community-related CSR ...has a stronger and quicker effect on stock returns than CSR toward customers and employees.•Publicly traded hospitality firms can invest in CSR during a pandemic to protect their firm value.•Hospitality firms’ historical CSR performance influences the effectiveness of CSR investment during the pandemic.
The novel coronavirus (COVID-19) pandemic has caused a significant decline in the stock market worldwide, and hospitality companies are experiencing serious financial problems. Protecting and preserving firm value is a critical way of helping hospitality companies survive the crisis. The influence of corporate social responsibility (CSR) on firm value has been widely investigated. However, little is known about the stock price movement following CSR activity adoption during an industrial crisis. Using event study and difference-in-difference method, this study reveals that engaging in CSR activities can increase the stock returns and stakeholder attention of hospitality firms during the pandemic. Community-related CSR has a stronger and more immediate effect on stock returns than customer- and employee-related CSR. Results also indicate that hospitality firms that pursue improved stock market performance during a pandemic can invest in CSR to protect communities, customers, and employees for attracting further stakeholder attention.
The radial jet drilling (RJD) is a key technology to improve the development efficiency of low-permeability oil and gas resources. In order to seek a reasonable hydraulic engineering parameter ...combination of hydraulic radial jet drilling, to obtain the optimal hydraulic energy distribution, a jet radial horizontal drilling simulation experiment system of the casing windowing is designed. A sequence of experimental investigations focused on engineering parameters of pump displacement, rotating speed, and frequency of high-pressure plunger pump is performed, and the operability and the feasibility of the experiment are verified. To evaluate the maximum drillable length and the self-propelled force of a jet nozzle, a 3D numerical model based on ANSYS-CFX is developed to evaluate the effects of the inlet flow displacement, the flow rates ratio K, and the angle ratio F:B of the forward orifice and backward orifice of the jet nozzle on its maximum drillable length and self-propelled force by sensitivity analysis. Finally, the comparison of numerical simulation results (Ln), mathematical results (Lm), and experiment results (Le) of the maximum drillable length are presented. It is observed that the simulation results are consistent with the experiment results with an average accuracy of 97.07%. Therefore, the proposed numerical model has a good performance in predicting the maximum drillable length of the multiorifice nozzle. The research results can provide theoretical guidance for improving the rock breaking and drilling capability of radial jet drilling technology.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, UILJ, UKNU, UL, UM, UPUK
LaMeAl11O19 ceramics is a kind of thermal barrier coating（TBC） material with promising application prospect due to its unique crystal structure, excellent thermodynamic properties, low thermal ...conductivity, and high temperature phase stability. Here, LaMeAl11O19/YSZ（Me=Mg, Cu, Zn） thermal barrier coatings were prepared by atmospheric plasma spraying（APS）. Failure analysis of the coating was carried out by burner rig test and other analysis techniques. The results show that LaMgAl11O19（LMA）, LaZnAl11O19（LZA） and LaCuAl11O19（LCA）powders are decomposed during the plasma spraying, resulting in different contents of magnetoplumbite phase in the coatings, which may be an important factor responsible for their distinction of thermal cycling lifetimes. The LaMeAl11O19 layer is delaminated upon YSZ layer due to mismatch of thermal expansion coefficient between LaMeAl11O19 layer and YSZ layer and volume shrinkage caused by recrystallization of amorphous phase. Then the YSZ layer is exposed high temperature, accelerating sintering and TGO growth, and promoting the delamination of the YSZ layer from the bond coat. At low temperature, with the increase of the atomic number of the divalent Me2+,the thermal conductivity of the LaMeAl11O19 decreases. At high temperature, LCA coating has better infrared emissivity（0.88, 600 ℃） than both LMA and LZA, which weakens the contribution of photon conduction to thermal conductivity and leads to the reduction of thermal conductivity. Therefore, LCA coating has potential application in high temperature infrared radiation coating.
La2Hf2O7 (LH) ceramics with pyrochlore structure have excellent phase stability up to 1600 °C, and far superior sintering resistance as well as comparable mechanical properties to typical 8 wt% ...yttria-stabilized zirconia (8YSZ). More importantly, they have the coefficients of thermal expansion (CTEs) of 8.76 × 10−6 K−1, lower than that of 8YSZ (10.38 × 10−6 K−1), and thermal conductivities of 1.34 W/m·K at 1000 °C, approximately 40% lower than that of 8YSZ (2.1–2.22 W/m·K). These comprehensive properties promote them as thermal insulation top-coats in thermal/environmental barrier coatings (T/EBCs) on ceramic-matrix composites (CMCs) or top-coats of double-ceramic-layered thermal barrier coatings (DCL-TBCs) on superalloys.
CBP/p300 interacting transactivator with Glu/Asp-rich carboxy-terminal domain 1 (CITED1) is a transcriptional activator belonging to the non-DNA-binding transcription co-regulator family. It ...regulates diverse pathways, including the transforming growth factor/bone morphogenetic protein/SMAD, estrogen, Wnt-β-catenin, and androgen-AR signaling pathways, by binding to CBP/p300 co-activators through its conserved transactivation domain CR2. CITED1 plays an important role in embryonic development and a certain regulatory role in the occurrence and development of various tumors. In this article, the biological characteristics, expression regulation, participating signaling pathways, and potential roles of CITED1 in the clinical diagnosis and treatment of tumors are reviewed.
In order to meet the requirements of automatic mapping of the smart substation models, based on the application requirements of the smart substation model construction and automatic model association ...configuration, the automatic generation technology of smart station diagram models is studied, and the automatic correlation modeling method and wiring diagram generation technology of primary and secondary equipment models based on the automatic matching of predefined correlation models are proposed. Support the realization of the goal of effective configuration and efficient application of the secondary system model of the smart substation.
BRAF
mutations, primarily sensitizing mutations, such as
BRAF
V600E
, have been proven to response to the
BRAF
inhibitor, Dabrafenib combined with trametinib therapy, but there have been no data ...demonstrating that it has activity against NSCLC-related brain metastases (BM). How patients harboring
BRAF
S365L
mutation (a rare mutation following
BRAF
V600E
-inhibitor treatment) in NSCLC is unknown. Vemurafenib, another
BRAF
inhibitor, can reverse the resistance that develops with the
BRAF
S365L
mutation following dabrafenib combined with trametentinib treatment in melanoma, but none has been reported in NSCLC. Lung papillary cancer, as a rare typing, occupies about 4% of NSCLC. Hence, we reported the first case of a patient with BM of lung papillary carcinoma harboring a
BRAF
V600E
mutation who benefited from dabrafenib combined with trametinib, and following the development of the
BRAF
S365L
mutation, vemurafenib remained an effective therapeutic option. Moreover, we found that the next-generation sequencing (NGS) of cerebrospinal fluid (CSF) circulating tumor DNA (ctDNA) may potentially provide more accurate information about intracranial lesions than ctDNA in the blood serum, which will be a better detection method.
LaMgAl11O19（LMA） coating prepared by atmospheric plasma spraying has large amounts of amorphous phase,which seriously affects the service life of coating.Effects of microstructure,such as grain ...size,porosity and amorphous phase content,on mechanical,thermophysical and thermal shock resistance properties of LMA coatings after heat-treatement at 900–1600℃for 12 h were investigated.The results show that the as-sprayed LMA coating possesses two crystallization temperature points,900 and 1163℃.After heat-treatement at 900℃,the lowest thermal diffusivity of 0.53 mm~2/s was obtained for LMA coating at 1000℃due to the large amount of amorphous phase and the highest porosity of （18.88±2.15）%.LMA coatings,heat-treated at 1100–1400℃,exhibited higher hardness owing to reduced amorphous content and porosity through recrystallization and sintering with the maximum hardness of （12.08±0.58） GPa at 1100℃.After heat-treatement at 1300℃,the coating displayed the highest average thermal cycling life （588 times）,which was attributed to abundant micron flake crystals with high strain tolerance.When the heat-treatment temperature reached 1500℃,the grain thickness increased rapidly due to parallel stacking of lamellar crystals,porosity increased and mechanical properties significantly decreased.During the thermal shock,grain breaking and crack propagation occurred in the coating due to the repeated thermal stress,resulting in final failure of the coating.
Thermal-sprayed coatings are expected to have a relatively smooth surface when used under certain service conditions, such as to improve their erosion resistance or decrease the adhesion of CMAS ...sands. In this study, a new method for grinding ceramic coatings was proposed that uses an industrial robot, a floating spindle, a rubber binder grinding head, and diamond plaster to automatically grind ceramic coatings on basis of free abrasive grinding. Typical 8YSZ thermal barrier coatings (TBCs) were created on nickel-based superalloy plates using atmospheric plasma spraying (APS) in order to explore the impact of such grinding on their morphology and comprehensive performance. Following the grinding with the proposed process, the coating's surface roughness, removal weight and thickness, as well as 3D surface morphology were all measured. The microstructure, wetting angle, infrared emittance, microhardness, bonding strength, particulate erosion resistance, and thermal cycling life of the as-sprayed and ground 8YSZ coatings were comparatively studied using the corresponding characterization instrument. The results show that the coating's surface roughness can be decreased to roughly 1 μm, and its removal thickness ranges between 45 and 90 μm. Besides from the wettability of the droplet on the coating's surface rises, the coating's infrared emittance, mechanical properties, thermal cycling life, and erosion resistance are not noticeably different after grinding, demonstrating that such novel grinding technique won't weaken the microstructure or shorten the coating life. It could offer guidance for the urgently required development of grinding processes for ceramic coatings with complex surfaces.
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