COVID-19 two years on: A review of COVID-19-related empirical research in major tourism and hospitality journals

Purpose: This study aims to provide a timely review of the COVID-19-related empirical research published in 19 quartile one (Q1) and quartile two (Q2) tourism and hospitality journals in social science citation index (SSCI). Design/methodology/approach: A total of 407 COVID-19-related empirical papers were collected from the 19 SSCI Q1 and Q2 tourism and hospitality journals via Scopus database. Thematic content analysis was supplemented with Leximancer software to identify the research themes/subthemes, research methods and countries/regions of research. Findings: The study found studies of COVID-19’s impact on consumer behaviour predominate in number, followed by studies on response actions and recovery strategies, impact on industry or sectors and impact on workers and employees. Based on the research themes identified, a knowledge mapping framework was produced. Over 70 % of the studies used quantitative methods with quantitative survey as the dominant method of data collection. The USA and China were found to be the most studied countries. Research limitations/implications: The study reviewed empirical research papers until January 2022 and covered most of the COVID-19-related empirical works in the field. An overview of the current state of COVID-19-related empirical research was provided with some critical discussions and suggestions for future research topics. Originality/value: The findings give researchers a clear index for the current state of the art of COVID-19 research in hospitality and tourism. The paper provides practical implications for industry practitioners to retrieve relevant knowledge from the recent COVID-19-related literature in tourism and hospitality in coping with practical challenges brought by the COVID-19 pandemic

Cross-cultural validation of the Chinese cultural value scale in tourism

This study aims to validate the Chinese Cultural Value Scale in Tourism (CCV-T) across cultures, using a sample of 405 Australian tourists. Through the application of Confirmatory Composite Analysis (CCA) within Partial Least Squares Structural Equation Modelling (PLS-SEM), the study demonstrates that the CCV-T scale exhibits excellent measurement qualities, including indicator reliability, construct reliability, convergent validity, discriminant validity, and nomological validity. The CCV-T scale comprises five dimensions: Life and Leisure Enjoyment (LLE), Filial Piety and Relationship (FPR), Self-fulfilment, Righteousness, and Humanity, consisting of 17 measurement items. The findings indicate that this scale is suitable for use with Australian tourists, representing a Western cultural context. Moreover, the CCV-T scale demonstrates its potential as a universal tool for measuring cultural values in tourism, applicable across various cultural and national contexts. This makes it a valuable instrument for future cross-cultural studies focusing on cultural values within the realm of tourism. This study makes a significant contribution to the field of cultural value studies in tourism by establishing a scale that is valid across different cultures. Industry professionals and policymakers can utilize this scale and its dimensions for purposes such as tourism product development and policy creation

The Operculum-Plug Area and Membranous Structure of the Eggs of Trichuris Trichiura

Eggs of Trichuris trichiura were prepared for scanning electron microscopy (SEM) by the dimethylsulfoxide freeze-cracking method. The egg-shell and oocyte were examined by SEM. The egg has a chitinous shell which consists of more than 10 layers of dense lamellae. The shell is bordered by a limiting membrane. An operculum and a collar made of chitinous shell together form the opercular area. The operculum is an empty cavity. The chitinous fibers of the egg-shell in this area are diffuse and loose, with numerous micropores or spaces. The egg-shell in this area therefore appears to form a fine tubular network. The oocyte is an undifferentiated cell with a biconcave drum-like shape. The perivitelline space is conspicuous at both ends of the cell

Fuzzy robust nonlinear control approach for electro-hydraulic flight motion simulator

AbstractA fuzzy robust nonlinear controller for hydraulic rotary actuators in flight motion simulators is proposed. Compared with other three-order models of hydraulic rotary actuators, the proposed controller based on first-order nonlinear model is more easily applied in practice, whose control law is relatively simple. It not only does not need high-order derivative of desired command, but also does not require the feedback signals of velocity, acceleration and jerk of hydraulic rotary actuators. Another advantage is that it does not rely on any information of friction, inertia force and external disturbing force/torque, which are always difficult to resolve in flight motion simulators. Due to the special composite vane seals of rectangular cross-section and goalpost shape used in hydraulic rotary actuators, the leakage model is more complicated than that of traditional linear hydraulic cylinders. Adaptive multi-input single-output (MISO) fuzzy compensators are introduced to estimate nonlinear uncertain functions about leakage and bulk modulus. Meanwhile, the decomposition of the uncertainties is used to reduce the total number of fuzzy rules. Different from other adaptive fuzzy compensators, a discontinuous projection mapping is employed to guarantee the estimation process to be bounded. Furthermore, with a sufficient number of fuzzy rules, the controller theoretically can guarantee asymptotic tracking performance in the presence of the above uncertainties, which is very important for high-accuracy tracking control of flight motion simulators. Comparative experimental results demonstrate the effectiveness of the proposed algorithm, which can guarantee transient performance and better final accurate tracking in the presence of uncertain nonlinearities and parametric uncertainties

Study on the cleaning and cooling of solar photovoltaic panels using compressed airflow

Solar photovoltaics (PV) are becoming one of the main sources of renewable energy to reduce carbon emissions of electricity supply. It is well recognised that dust accumulation and high temperatures result in a dramatic reduction in the performance of PV panels. To improve the efficiency of solar PV panels, a compressed air-based regulation method which can simultaneously clean and cool PV panels is studied and tested. A modelling study of the dust adhesion and detachment mechanism is conducted and the temperature variation caused by the air blowing process is analysed. Dynamic models of the compressed air release are derived which can be used to guide the design of the regulation system for increasing PV power output. A test system is developed for verifying various design and system parameters. The test results are used to validate the suitability of the modelling and illustrate how the inefficiency arising from soiling and high temperatures can be mitigated with the regulated compressed airflow. PV arrays serving in an arid region are adopted for this study and the increased energy yield arising from the cleaning and cooling effects is evaluated via the experimental test. The relationship between the airflow duration, various sizes of particles cleaning from the surface and power generation efficiency improvement is investigated to maximise the net power output increase from the PV panel. The results of this study can contribute to improving PV efficiency and help to realise decarbonisation in energy industry

Combined capacity and operation optimisation of lithium-ion battery energy storage working with a combined heat and power system

Combined Heat and Power (CHP) systems are considered as a transitional solution towards zero carbon emissions in the next couple of decades. The current CHP systems are mainly controlled by thermal led strategy, that is, the electrical power generation depends on the thermal energy demand. The mismatch between the power generation and load demand leads to the deficient energy utilisation and economic loss. An innovative combined planning method is proposed in the paper to improve the economic gains of the CHP systems by integrating the lithium-ion battery storage system (LBSS). The paper focuses on the simultaneous optimisation of storage capacity design and operation strategy formulation of the LBSS subject to the variations of the load and power generation from CHP with consideration of LBSS degradation and cost, and Time-of-Use pricing structures. The new strategy is implemented and tested using the University of Warwick campus CHP system combined with the LBSS facilities. The results show that the method could improve the economic performance of CHP systems. The developed method is applicable to any CHP systems optimisation with integrated LBSS

Techno-economic analysis of bulk-scale compressed air energy storage in power system decarbonisation

Although the penetration of renewable energy in power systems has been substantially increased globally in the last decade, fossil fuels are still important in providing the essential flexibility required to reliably maintain the system balance. In 2019, more than one quarter of power generation in Europe and over 40% of the UK’s electricity generation was from fossil fuels (mainly gas). For achieving the net-zero greenhouse gas emission target around the middle of this century, these fossil fuels have to be decarbonised in the coming decades. Bulk-scale energy storage has been recognised as a key technology to overcome the reduced dispatchability associated with the decrease of fossil fuels in generation. Taking the UK power system as a case study, this paper presents an assessment of geological resources for bulk-scale compressed air energy storage (CAES), and an optimal planning framework for CAES in combination with solar and wind to replace fossil fuels in the power generation system. The analysis reveals up to 725 GWh of ready-to-use capacity by utilising existing underground salt caverns in the UK. These potential CAES sites with added solar and wind generation equal to the generation from fossil fuels in 2018 can reduce carbon emissions by 84% with a cost increase by 29%, compared to the system in 2018. The results indicate the plausibly achievable cost-effectiveness of CAES as bulk-scale energy storage for power system decarbonisation in countries the geological resources are available

Characterization of two immunomodulating homogalacturonan pectins from green tea

Two natural homogalacturonan (HG) pectins (MW ca. 20 kDa) were isolated from green tea based on their immunomodulatory activity. The crude tea polysaccharides (TPS1 and TPS2) were obtained from green tea leaves by hot water extraction and followed by 40% and 70% ethanol precipitation, respectively. Two homogenous water soluble polysaccharides (TPS1-2a and TPS1-2b) were obtained from TPS1 after purification with gel permeation, which gave a higher phagocytic effect than TPS2. A combination of composition, methylation and configuration analyses, as well as NMR (nuclear magnetic resonance) spectroscopy revealed that TPS1-2a and TPS1-2b were homogalacturonan (HG) pectins consisting of a backbone of 1,4-linked α-d-galacturonic acid (GalA) residues with 28.4% and 26.1% of carboxyl groups as methyl ester, respectively. The immunological assay results demonstrated that TPS1-2, which consisted mainly of HG pectins, showed phagocytosis-enhancing activity in HL-60 cells

Hybrid surgery for coexistence of cerebral arteriovenous malformation and primitive trigeminal artery: A case report and literature review

The primitive trigeminal artery (PTA), an abnormal carotid-basilar anastomosis, forms the vascular anomaly connection between the internal carotid artery and vertebrobasilar system. Rarely, PTA can be complicated by several other cerebrovascular disease, including arteriovenous malformations (AVMs), intracranial aneurysms, moyamoya disease, and carotid-cavernous malformations. Herein, we reported a rare case of PTA combined with an AVM in a male patient. The patient was a 28-year-old male with epileptic seizures at the onset of symptoms. Magnetic resonance imaging showed abnormal signal foci and localized softening foci formation with gliosis in the right parietal temporal lobe. Furthermore, using a digital subtraction angiogram (DSA), it was found that an abnormal carotid-basilar anastomosis had developed through a PTA originating from the cavernous portion of the right internal carotid artery (ICA) and a large AVM on the surface of the right carotid artery. The lesion of AVM tightly developed and draining into superior sagittal sinus. A hybrid operating room was used for the surgery. The main feeding arteries of the AVM originating from three major arteries, including the right middle cerebral artery, the right anterior cerebral artery, and the right posterior cerebral artery, were clipped and subsequently, then the AVM was thoroughly removed. The intraoperative DSA showed that the AVM had been resected completely. Postoperative pathological examination of the resected specimen indicated the presence of an AVM. The patient recovered well after surgery and has been symptom-free for more than 3 months. In summary, the pathogenesis of the coexistence of PTA and AVM remains unknown. As highlighted in this case report, hybrid surgery can be used to remove AVMs and can improve the patients' prognosis. To our best knowledge, this is the first case in the literature of successful AVM treatment using hybrid surgery

Homoisoflavonoids are potent glucose transporter 2 (GLUT 2) inhibitors–a potential mechanism for the glucose-lowering properties of Polygonatum odoratum

Foods of high carbohydrate content such as sucrose or starch increase postprandial blood glucose concentrations. The glucose absorption system in the intestine comprises two components: sodium-dependent glucose transporter-1 (SGLT1) and glucose transporter 2 (GLUT2). Here five sappanin-type (SAP) homoisoflavonoids were identified as novel potent GLUT2 inhibitors, with three of them isolated from the fibrous roots of Polygonatum odoratum (Mill.) Druce. SAP homoisolflavonoids had a stronger inhibitory effect on 25 mM glucose transport (41.6 ± 2.5, 50.5 ± 7.6, 47.5 ± 1.9, 42.6 ± 2.4, and 45.7 ± 4.1% for EA-1, EA-2, EA-3, MOA, and MOB) than flavonoids (19.3 ± 2.2, 11.5 ± 3.7, 16.4 ± 2.4, 5.3 ± 1.0, 3.7 ± 2.2, and 18.1 ± 2.4% for apigenin, luteolin, quercetin, naringenin, hesperetin, and genistein) and phloretin (28.1 ± 1.6%) at 15 μM. SAP homoisoflavonoids and SGLT1 inhibitors were found to synergistically inhibit the uptake of glucose using an in vitro model comprising Caco-2 cells. This observed new mechanism of the glucose-lowering action of P. odoratum suggests that SAP homoisoflavonoids and their combination with flavonoid monoglucosides show promise as naturally functional ingredients for inclusion in foods and drinks designed to control postprandial glucose levels