bluuebunny/crossref_metadata_2025 huggingface dataset:
A Novel MIMO Array with Reduced Mutual Coupling and Increased Degrees of Freedom
Authors: Liu Mingxin , Zou Lin , Ren Haohao , Yu Xuelian , Zhou Yun , Wang Xuegang
Published: February 2021

In this paper, we consider the problem of array design for Multiple-Input Multiple-Output (MIMO) array under the condition of fixed number of physical sensors and mutual coupling. A novel MIMO array based on the second-order super nested transmit and receive arrays is proposed by using the difference coarray. It can obtain the closed form expressions for the physical sensor locations and the degrees of freedom (DOF) from any given number physical sensors. The proposed array structure can significantly enhance DOF and effectively decrease unknown mutual coupling effect. The effectiveness and superiority of the proposed MIMO array structure are verified from the number of DOF and MUSIC spectra by numerical simulations.
Numerical Simulation of Gas Ventilation Mode in Highway Gas Tunnel
Authors: Zhang Jihua , Dong Yun , Chen Yadong , Sun Huasheng , Wu Jingke , Liu Weili , Chen Jiarui , Pan Shiqiang
Published: February 2021

When the mountain tunnel projects passing through the complex formation with coal, it happened along with disaster accidents such as gas outburst, gas combustion, and gas explosion. These disasters should seriously threaten the safety and life of the construction personnel and affect the normal operation of the tunnel construction. Ventilation is the most effective means to control gas, fire, dust, heat, and other disasters. To study the effects of different ventilation modes in highway gas tunnels, Fluent software was used to simulate forced ventilation, exhaust ventilation, and mixed ventilation in a high gas tunnel of a highway in Hunan. The distribution law of the airflow velocity and gas concentration of these three ventilation modes were obtained to determine the optimal ventilation system. It was shown that vortex zones of different ranges formed in the tunnel for all three ventilation modes, and the gas concentration was higher in the vortex zone than in other regions. Mixed ventilation of them is superior to the other two modes, showing the best ventilation effect with regard to airflow velocity and gas concentration.
Research on Full-Section Anchor Cable and C-Shaped Tube Support System of Deep Layer Roadway
Authors: Shan Renliang , Zhang Shupeng , Huang Pengcheng , Liu Weijun
Published: February 2021

Deep roadway deformation due to soft rock, rock dip, and horizontal tectonic stress is uneven and asymmetrical primarily in large loose zones. Traditional anchor support is influenced by the yield strength and shear strength of the anchors and has a limited prestress capacity or shear resistance. When the roadway roof is laminated rock or when the roadway passes through layered rock or rock interfaces, interlayer sliding commonly occurs, which can easily lead to anchor cables being sheared off. The tape tunnel in the Zhengling Mine passes through several rock strata and requires anchors to achieve a high shear resistance and prestress. To solve these problems, an anchor cable and C-shaped tube that can bear lateral shear forces were developed, and a full-section anchor cable and C-shaped tube support system were created based on extruded arch theory. Numerical results from FLAC3D show that the new scheme effectively controls surface convergence and plastic zone extension. Field tests have demonstrated that the amount of surface displacement was at least 42% smaller in the new support scheme. The extruded arch formed by the highly prestressed anchor cable and concrete spray layer can effectively control the bulking load within the loose zone, and the ACC effectively resists interlayer shear.
A System of Two Diophantine Inequalities with Primes
Authors: Han Xue , Liu Huafeng , Zhang Deyu
Published: February 2021

Let

1
<
d
<
c
<

128

/

119

,

1
<
α
<
β
<

6

1
−
d

/
c

. In this paper, we prove that there exist positive real numbers

N
1

0

and

N
2

0

depending on

c
,
d
,
α
,
β

such that for all real numbers

N

1

>

N
1

0

,

N

2

>

N
2

0

and

α
≤

N

2

/

N
1

d
/
c

≤
β

, the system of two Diophantine inequalities

p
1
c

+
⋯
+

p
6
c

−

N

1

<

N
1

−

1
/
c

128
/

119
−
c

log

109

N

1

,

p
1
d

+
⋯
+

p
6
d

−

N

2

<

N
2

−

1
/
d

128
/

119
−
d

log

109

N

2

is solvable in prime variables

p

1

,
…
,

p

6

.
A High-Performance Indirect Torque Control Strategy for Switched Reluctance Motor Drives
Authors: Li Cunhe , Zhang Cunshan , Liu Jian , Bian Dunxin
Published: February 2021

This paper proposes a high-performance indirect control scheme for torque ripple minimization in the switched reluctance motor (SRM) drive system. Firstly, based on the nonlinear torque-angle characteristic of SRM, a novel torque sharing function is developed to obtain the optimal current profiles such that the torque ripple is minimized with reduced copper losses. Secondly, in order to track current accurately and indirectly achieve high-performance torque control, a robust current controller is derived through the Lyapunov stability theory. The proposed robust current controller not only considers the motor parameter modeling errors but also realizes the fixed frequency current control by introducing the pulse width modulation method. Further, a disturbance-observer-based speed controller is derived to regulate the motor speed accurately, and the load torque is considered an unknown disturbance. The simulations and experiments on a 1.5 kW SRM prototype are carried out to demonstrate the effectiveness of the proposed high-performance indirect torque control strategy. Results verify the superiority of the proposed strategy with respect to the torque ripple suppression, system efficiency, and antidisturbance.
Numerical Studies of Particle‐Gas Two‐Phase Flowing through Microshock Tubes
Authors: Zhang Guang , Wang Wei Wei , Su Xiang Hui , Li Xiao Jun , Shen Wen Hao , Lin Zhe
Published: February 2021

Microshock tubes are always used to induce shock waves and supersonic flows in aerospace and medical engineering fields. A needle‐free drug delivery device including a microshock tube and an expanded nozzle is used for delivering solid drug powders through the skin surface without any injectors or pain. Therefore, to improve the performance of needle‐free drug delivery devices, it is significantly important to investigate shock waves and particle‐gas flows induced by microshock tubes. Even though shock waves and multiphase flows discharged from microshock tubes have been studied for several decades, the characteristics of unsteady particle‐gas flows are not well known to date. In the present studies, three microshock tube models were used for numerical simulations. One microshock tube model with closed end was used to observe the reflected shock wave and flow characteristics behind it. The other two models are designed with a supersonic nozzle and a sonic nozzle at the exit of the driven section, respectively, to investigate particle‐gas flows induced by different nozzles. Discrete phase method (DPM) was used to simulate unsteady particle‐gas flows and the discrete random walk model was chosen to record the unsteady particle tracking. Numerical results were obtained for comparison with those from experimental pressure measurement and particle visualization. Shock wave propagation was observed to agree well with experimental results from numerical simulations. Particles were accelerated at the exit of microshock tube due to the reservoir pressure induced by reflected shock wave. Both sonic and supersonic nozzles were underexpanded at the end of microshock tubes. Particle velocity was calculated to be smaller than gas velocity, which results from larger drag of injected particles.
Forecast of Short-Term Electricity Price Based on Data Analysis
Authors: Wu Shuang , He Li , Zhang Zhaolong , Du Yu
Published: February 2021

The decision-making of power generation enterprises, power supply enterprises, and power consumers can be affected by forecasting the price of electricity. There are many irrelevant samples and features in big data, which often lead to low forecasting accuracy and high time-cost. Therefore, this paper proposes a forecasting framework based on big data processing, which selects a small quantity of data to achieve accurate forecasting while reducing the time-cost. First, the sample selection based on grey correlation analysis (GCA) is established to eliminate useless samples from the periodicity. Second, the feature selection based on GCA is established considering the feature classification and the temporal correlation features to further eliminate useless features. Third, principal component analysis is applied to reduce the noise among the data. Then, combined with a differential evolution algorithm (DE), a support-vector machine (SVM) is applied to forecast the price. Finally, the proposed framework is applied to the New England electricity market to forecast the short-term electricity price. The results show that, compared with DE-SVM without data processing, the forecasting accuracy is improved from 81.68% to 91.44%, and the time-cost is decreased from 35,074 s to 1,809 s which shows that the proposed method and model can provide a valuable tool for data processing and forecasting.
Conductivity Characterization of Insulation and Its Effects on the Calculation of the Electric Field Distribution in HVDC Cables
Authors: Liu Shili , Wei Wei , Liu Tao , Hui Zhaoyu , Hang Yuhua , Zheng Huan , Suo Changyou , Li Zhonghua
Published: February 2021

The calculation of an electric field distribution provides the basis for the structural design of the insulation, and an accurate characterization of conductivity as a function of temperature and electric field forms an important basis for the simulation of the electric field distribution in HVDC (high-voltage direct current) cables. However, the conductivity functions that describe the insulating materials used for HVDC cables in different studies are different, and very little has been reported regarding how to choose the most accurate function. In this work, the conductivity of insulating materials used for HVDC cables is characterized, and the effects of the conductivity characterization on the simulation of the electric field in HVDC cables are studied. First, eight common conductivity functions are compared qualitatively. Then, the conductivities of XLPE for different temperatures and electric fields are measured, and a data fitting technique is used to analyze the coincidence degree between different functions and the test results. Finally, the steady-state electric field distributions of HVDC cables for different temperature gradients are simulated in COMSOL Multiphysics. The results show that the sum of the square of the relative errors of the fitting when using the original functions is larger than that achieved when using the logarithmic form of the functions. The deviations in the electric field caused by taking the logarithm of different functions are smaller.
A Mathematical Model of the Hydrodynamic Pressure Acting on a Turbine Runner Blade under the Rotor-Stator Interaction Based on the Quasi-Three-Dimensional Finite Element Method
Authors: Wang Yujiang , Li Zhaojun , Li Tinghao , Liu Fuxiu , Fu Aijun
Published: February 2021

In this paper, a turbine runner blade under hydraulic excitation was taken as the object of study and the mathematical hydrodynamic pressure model of a turbine runner blade under the rotor-stator interaction was established using quasi-three-dimensional finite element model. The regularity of the distribution of the hydrodynamic pressure was then investigated. First, the quasi-three-dimensional finite element model of a runner blade was established using the quasi-three-dimensional theory. Next, according to the pressure distribution from the numerical simulation, the mathematical mean pressure model of a node was established using the relative pressure difference method; the pressure fluctuation was then established taking the rotor-stator interaction into consideration. Then, based on the mean pressure and the pressure fluctuation of a node, the mathematical hydrodynamic pressure model for any position of a runner blade was obtained. Finally, the feasibility of the mathematical model was verified by an example analysis, and the internal relationship between the hydrodynamic pressure and its hydraulic parameters and the structural parameters of the blade was revealed, which provides a theoretical basis for further study of the dynamic characteristics of turbine runner blades under the rotor-stator interaction.
Experimental Study on Flow Characteristics of Aeolian Sand in Fractures
Authors: Chen Jiarui , Gu Wenhu , Zhang Jihua , Tang Jitao , Cao Zhengzheng , Wu Jingke , Liu Jianxiong , He Weizhong , Shi Fang
Published: February 2021

It is one of the important safety problems in the process of mining shallow coal seams in western China that the rock mass affected by mining stress breaks and forms a penetrating fracture, leading to a sand burst in the working face. The self‐developed test system is used to carry out the experimental study on the flow characteristics of Aeolian sand in fractures. The research work is focused on the influence of several parameters, such as the thickness of the Aeolian sand layer, the fracture opening, and the fracture dip angle on the velocity of sand particles in fractures. The results show the following: (1) The influence of fracture opening and fracture angle on sand burst rate is much greater than that of sand thickness. No matter what the fracture angle and fracture opening value are, the influence weight of sand thickness on sand burst rate is almost zero. (2) When other conditions are unchanged, with the increase of fracture dip angle, the sand burst rate increases significantly, and the relationship between the sand burst rate and the fracture dip angle is exponential. (3) The influence weight of fracture opening is the largest. With the increase of fracture opening, the sand burst rate increases logarithmically. Finally, according to the test results, the relation equation which can simultaneously describe the influence of fracture opening and fracture inclination on the rate of the sand burst is fitted. This study can provide a theoretical basis and scientific guidance for the prevention and control of coal mine sand inrush disasters caused by roof cracking in western coal mines.
Frame Structure and Engineering Applications of the Multisource System Cloud Service Platform of Monitoring of the Soft Rock Tunnel
Authors: Wang Fengnian , Yin Songyang , Guo Aipeng , Wang Zhicai , Mi Meng , Qi Gan , Ma Juan , Zhang Haijiang
Published: February 2021

Throughout engineering construction, large deformation disasters in soft rock tunnels are encountered increasingly frequently. Therefore, structural health monitoring not only ensures accurate construction management but also provides a basis for dynamic adjustment of the support structure. The existing monitoring technology has certain shortcomings, such as poor anti-interference ability, non-real-time operation, and great security risks. Consequently, high-precision real-time monitoring has become a key scientific issue in tunnel engineering. For this work, multisource information fusion technology was adopted, while data security reserve systems, such as cloud server (ECS) based on the fiber Bragg grating multisource sensing system, cloud database (RDS), and cloud website, were embedded into the No. 2 inclined shaft of the Muzhailing tunnel. Based on the negative Poisson’s ratio (NPR) anchor cable control technology for large deformation of the soft rock in the No. 2 inclined shaft of the Muzhailing tunnel, reasonable and effective intelligent monitoring was carried out for tunnel construction. Monitoring and early warning cloud service platforms, based on the Internet of Things and cloud technology, could quickly produce query and statistic tunnel monitoring information. The monitoring system provided the collection, transmission, storage, processing, and early warning information sending of data, such as NPR anchor cable axial force, steel arch stress, deep surrounding rock displacement, surrounding rock deformation, and contact pressure between primary support with secondary lining. This monitoring system ensured construction safety and provided monitoring application case support for the related problems of similar projects.
On the Analytical Solutions of the Forced Damping Duffing Equation in the Form of Weierstrass Elliptic Function and its Applications
Authors: El-Tantawy S. A. , Salas Alvaro H. , Alharthi M. R.
Published: February 2021

In this study, a novel analytical solution to the integrable undamping Duffing equation with constant forced term is obtained. Also, a new approximate analytical (semianalytical) solution for the nonintegrable linear damping Duffing oscillator with constant forced term is reported. The analytical solution is given in terms of the Weierstrass elliptic function with arbitrary initial conditions. With respect to it, the semianalytical solution is constructed depending on a new ansatz and the exact solution of the standard Duffing equation (in the absence of both damping and forced terms). A comparison between the obtained solutions and the Runge–Kutta fourth-order (RK4) is carried out. Moreover, some complicated oscillator equations such as the constant forced damping pendulum equation, forced damping cubic-quintic Duffing equation, and constant forced damping Helmholtz–Duffing equation are reduced to the forced damping Duffing oscillator, in which its solution is known. As a practical application, the proposed techniques are applied to investigate the characteristics behavior of the signal oscillations arising in the RLC circuit with externally applied voltage.
The Magnetic Bead Computing Model of the 0-1 Integer Programming Problem Based on DNA Cycle Hybridization
Authors: Xu Rujie , Yin Zhixiang , Tang Zhen , Yang Jing , Cui Jianzhong , Wang Xiyuan
Published: February 2021

Magnetic beads and magnetic Raman technology substrates have good magnetic response ability and surface-enhanced Raman technology (SERS) activity. Therefore, magnetic beads exhibit high sensitivity in SERS detection. In this paper, DNA cycle hybridization and magnetic bead models are combined to solve 0-1 integer programming problems. First, the model maps the variables to DNA strands with hairpin structures and weights them by the number of hairpin DNA strands. This result can be displayed by the specific binding of streptavidin and biotin. Second, the constraint condition of the 0-1 integer programming problem can be accomplished by detecting the signal intensity of the biological barcode to find the optimal solution. Finally, this model can be used to solve the general 0-1 integer programming problem and has more extensive applications than the previous DNA computing model.
Antioxidant Activity of Sprouts Extracts Is Correlated with Their Anti-Obesity and Anti-Inflammatory Effects in High-Fat Diet-Fed Mice
Authors: Kwak Chung Shil , Kim Mi-Ju , Park Sunyeong , Kim In Gyu
Published: February 2021

Obesity is closely associated with oxidative stress and chronic inflammation leading to related metabolic diseases. Some natural extracts or polyphenols reportedly possess anti-obesity and anti-inflammatory effects as well as antioxidant activity. In this study, we assessed the correlations between the antioxidant, anti-obesity, and anti-inflammatory activities of plant extracts with potent antioxidant activity in diet-induced obese mice. Sprouts of Cedrela sinensis (CS) and Oenothera biennis L. (OB) were selected as the most potent antioxidant plant based on analysis of in vitro antioxidant activity of the extracts of ten different edible plants. C57BL/6 mice were fed with a high-fat diet (HFD) and orally treated with 50% ethanol extract of CS or OB at 50 or 100 mg/kg body weight 5 days a week for 14 weeks. Body weight gain, weight of adipose tissue, adipocyte size, and levels of lipid metabolism, inflammation, and oxidative stress markers were investigated. The CS or OB extract reduced body weight gain, visceral adipose tissue weight, adipocyte size, and plasma leptin levels, and expressions of adipogenic genes (PPARγ and fatty acid synthase) in the adipose tissue and liver of HFD-fed mice. Both extracts also reduced mRNA levels of pro-inflammatory cytokines (IL-6 and TNF-α) and oxidative stress-related genes (heme oxygenase- (HO-) 1 and p40phox). Body weight gain of mice was significantly correlated with visceral adipose tissue weight and adipocyte size. Body weight gain and adipocyte size were significantly correlated with plasma total cholesterol and 8-epi PGF2α levels, mRNA levels of leptin, HO-1, p40phox, and CD-11 in the adipose tissue, and mRNA levels of TNF-α in the adipose tissue and liver. These results suggest that the CS and OB extracts with potent antioxidant activity may inhibit fat deposition in adipose tissue and subsequent inflammation.
A Real-Time Star Tailing Removal Method Based on Fast Blur Kernel Estimations
Authors: Hou Yaxian , Zhao Rujin , Ma Yuebo , He Longdong , Zhu Zifa
Published: February 2021

The number of star points and the accuracy of star centroid extraction are the key factors that affect the performance of the star sensor under high dynamic conditions. The motion blur results in the star point trailing, which consequently leads to the decline of star centroid extraction accuracy and in some cases lead to extraction failure. In order to improve the dynamic performance of the star sensor, in this work, we propose a real-time star trailing removal method based on fast blur kernel estimation. First, in order to minimize the influence of noise on parameter estimation, we use principal component analysis (PCA) in the dual-frequency spectrum domain to estimate the angle of blur kernel. In addition, an adjustable weighting method is proposed to estimate the length of blur kernel. So, we are able to quickly estimate the high-precision blur kernel based on a single degraded image. Moreover, an area filtering method based on the hyper-Laplacian prior recovery algorithm is also proposed. This algorithm quickly reconstructs the star points in the tracking windows and effectively removes the star point tailing in real time. The computational efficiency of the proposed algorithm is 5 times superior to the traditional method and 15 times superior to the existing accelerated iterative method. The experimental results show that the proposed algorithm removes the trailing star quickly and effectively, under low SNR. In addition, the proposed method effectively improves the number of extracted star points and the accuracies of star centroids.
Wet Modal Analyses of Various Length Coaxial Sump Pump Rotors with Acoustic‐Solid Coupling
Authors: Peng Guangjie , Zhang Zhuoran , Bai Ling
Published: February 2021

The dynamic characteristics of the rotor components were determined using a first‐order modal model of the rotor components for various sump pump shaft lengths for actual working environments. By employing ANSYS‐Workbench software, this paper uses a fluid‐solid coupling analysis to calculate the reaction forces of the fluid on the rotor with results, which is then used in dry and wet modal analyses of the rotor parts to calculate the vibration modal characteristics with and without prestresses. The differences between the wet and dry modal characteristics were compared and investigated by ANSYS. The results show that increasing the sump pump shaft length reduces the first‐order natural frequency of the prestressed rotor components. The structure also experiences stress stiffening, which is more obvious in the high‐order modes. The natural frequency of the rotor in the wet mode is about 16% less than that in the dry mode for the various shaft lengths due to the added mass of the water on the surface which reduces the natural frequency. In the wet modal analysis, when the structure is in a different fluid medium, the influence of its modal distribution will also change, this is because the additional mass produced by the fluid medium of different density on the structure surface is different. Thus, the wet modal analysis of the rotor is important for more accurate dynamic analyses.
Development and Sensory Evaluation of Omega-3-Rich Nile Perch Fish Oil-Fortified Yogurt
Authors: Murage Margaret W. , Muge Edward K. , Mbatia Betty N. , Mwaniki Mercy W.
Published: February 2021

Nile perch (Lates niloticus) is a major fish species in East Africa and its processing produces sufficient amounts of by-products containing significant amounts of long-chain polyunsaturated fatty acids (PUFAs). Due to the health benefits associated with PUFAs, they can be incorporated into commonly consumed foods such as yoghurt. This study is aimed at developing an omega-3-rich functional yoghurt and evaluating its quality and acceptability. Omega-3-rich fish oils were obtained from Nile perch fat pads in the presence and absence of a commercial food grade enzyme Alcalase. Recovery of omega-3-rich fish oil was done by centrifugation at

1000
×
g

at room temperature. The peroxide value (PV), anisidine value (AV), total oxidation (TOTOX), and free fatty acids (FFA) were some of the quality parameters investigated. Natural yoghurt (150 ml) was prepared and spiked with 3.5 g of omega-3-rich Nile perch oil. To mask the fishy flavor and taste, four different flavors were used and sensory evaluation of the yoghurt samples was performed. The liberation of Nile perch fish oil in the absence of Alcalase gave better yield (60.7% wet weight), while the use of Alcalase gave lower yields (48.3% wet weight). Assessment of the quality of the extracted fish oils showed that all parameters were within the required limits. Sensory characterization by a panel of students showed that passion and strawberry flavors were the most liked with mean values of 4.65 and 4.625, respectively. This study revealed that substantial amounts of omega-3-rich fish oil can be extracted from Nile perch fish pads in the absence of exogenous enzymes. Fortification of yoghurt with omega-3-rich Nile perch fish oils is an approach towards increasing omega-3 intake within the Kenyan population and globally.
Pore Structure Characteristics and Permeability Prediction Model in a Cretaceous Carbonate Reservoir, North Persian Gulf Basin
Authors: Lu Hao , Tang Hongming , Wang Meng , Li Xin , Zhang Liehui , Wang Qiang , Zhao Yulong , Zhao Feng , Liao Jijia
Published: February 2021

Due to the diversity of pore types, it is challenging to characterize the Middle East’s Cretaceous carbonate reservoir or accurately predict its petrophysical properties. In this paper, pore structure in the reservoir is first classified using a comprehensive method. Then, based on the identified pore structure types, a new permeability model with high prediction precision is established. The reservoir is dominated by 6 pore types, such as intergrain pores and moldic pores, and 6 rock types. Grainstone, algal packstone, algal wackestone, and foraminifera wackestone are porous rock types, and echinoderm wackestone and mudstone are nonporous rock types. The types of pore structure in the study area can be divided into four types. Type I has midhigh porosity and medium-high permeability due to its large throat, while type II has a fine throat type with midhigh porosity and midpermeability. Due to their isolated pores, the permeability is low in types III and IV, and out of these two, type III has better storage capacity. Movable fluid saturation calculated by the spectral coefficient method andrapexcan characterize the boundary between the connected pores and unconnected pores very well in the research area. It is not accurate enough to simply classify the pore structure by permeability and porosity. The combination of porosity, permeability,rapex, flow zone indicator, and the reservoir quality index can effectively distinguish and classify pore structure types in noncoring wells. The characteristics of each pore structure type are consistent with those of the fractal dimension, which thereby proves the effectiveness of the pore structure classification. New permeability prediction models are proposed for different pore structure types, and good prediction results have been obtained. This study is of great significance for enhancing oil recovery.
Mitochondrial Inhibitor Atovaquone Increases Tumor Oxygenation and Inhibits Hypoxic Gene Expression in Patients with Non–Small Cell Lung Cancer
Authors: Skwarski Michael , McGowan Daniel R. , Belcher Elizabeth , Di Chiara Francesco , Stavroulias Dionisios , McCole Mark , Derham Jennifer L. , Chu Kwun-Ye , Teoh Eugene , Chauhan Jagat , O’Reilly Dawn , Harris Benjamin H.L. , Macklin Philip S. , Bull Joshua A. , Green Marcus , Rodriguez-Berriguete Gonzalo , Prevo Remko , Folkes Lisa K. , Campo Leticia , Ferencz Petra , Croal Paula L. , Flight Helen , Qi Cathy , Holmes Jane , O’Connor James P.B. , Gleeson Fergus V. , McKenna W. Gillies , Harris Adrian L. , Bulte Daniel , Buffa Francesca M. , Macpherson Ruth E. , Higgins Geoff S.
Published: February 2021

Purpose:

Tumor hypoxia fuels an aggressive tumor phenotype and confers resistance to anticancer treatments. We conducted a clinical trial to determine whether the antimalarial drug atovaquone, a known mitochondrial inhibitor, reduces hypoxia in non–small cell lung cancer (NSCLC).

Patients and Methods:

Patients with NSCLC scheduled for surgery were recruited sequentially into two cohorts: cohort 1 received oral atovaquone at the standard clinical dose of 750 mg twice daily, while cohort 2 did not. Primary imaging endpoint was change in tumor hypoxic volume (HV) measured by hypoxia PET-CT. Intercohort comparison of hypoxia gene expression signatures using RNA sequencing from resected tumors was performed.

Results:

Thirty patients were evaluable for hypoxia PET-CT analysis, 15 per cohort. Median treatment duration was 12 days. Eleven (73.3%) atovaquone-treated patients had meaningful HV reduction, with median change −28% [95% confidence interval (CI), −58.2 to −4.4]. In contrast, median change in untreated patients was +15.5% (95% CI, −6.5 to 35.5). Linear regression estimated the expected mean HV was 55% (95% CI, 24%–74%) lower in cohort 1 compared with cohort 2 (P = 0.004), adjusting for cohort, tumor volume, and baseline HV. A key pharmacodynamics endpoint was reduction in hypoxia-regulated genes, which were significantly downregulated in atovaquone-treated tumors. Data from multiple additional measures of tumor hypoxia and perfusion are presented. No atovaquone-related adverse events were reported.

Conclusions:

This is the first clinical evidence that targeting tumor mitochondrial metabolism can reduce hypoxia and produce relevant antitumor effects at the mRNA level. Repurposing atovaquone for this purpose may improve treatment outcomes for NSCLC.
A Case of Alpha-Pyrrolidinopentiophenone (Flakka)-Induced Ischemic Stroke
Authors: Heinonen Tommi , Korvenoja Antti , Pekkonen Eero
Published: February 2021

Alpha-pyrrolidinovalerophenone (α-PVP) is a designer drug, the mechanism of action of which resembles that of cocaine and amphetamine. New data about the side effects of α-PVP are emerging. We present a case report of an acute ischemic stroke following the recreational use of α-PVP. The ischemic lesions were located in the middle cerebral artery and deep watershed areas of the left cerebral hemisphere. Occupational therapy and physiotherapy were initiated, and the patient was discharged with only a mild right hemiparesis.
Regional Changes in Patterns of Stroke Presentation During the COVID-19 Pandemic
Authors: Etherton Mark R. , Zachrison Kori S. , Yan Zhiyu , Sveikata Lukas , Bretzner Martin , Estrada Juan , Viswanathan Anand , Singhal Aneesh B. , Schwamm Lee H.
Published: February 2021

Background and Purpose:

Patient care-seeking has likely changed during the coronavirus disease 2019 (COVID-19) pandemic. In stroke, delayed or avoided care may translate to substantial morbidity. We sought to determine the effect of the pandemic on patterns of stroke patient presentation and quality of care.

Methods:

We analyzed data from 25 New England hospitals: one urban, academic comprehensive stroke center and telestroke hub, and 24 spoke hospitals in the telestroke network. We included all telestroke consultations from the 24 spokes, and all stroke admissions to the comprehensive stroke center hub from November 1, 2019 through April 30, 2020. We compared rates of presentation, timeliness presentation, and quality of care pre- versus post-March 1, 2020. We examined trends in patient demographics, stroke severity, timeliness, diagnoses including large vessel occlusion, alteplase use, and endovascular thrombectomy among eligible subjects. We compared proportions and bivariate comparisons to examine for changes pre- versus post-March 1, 2020 and used linear regression to examine trends over time.

Results:

Among 1248 patient presentations (844 telestroke consultations, 404 comprehensive stroke center admissions), telestroke consultations and ischemic stroke patient admissions decreased among the spokes and hub. Age and stroke severity were unchanged over the study period. We found no change in alteplase administration at telestroke spoke hospitals but did note a decrease in both alteplase use and thrombectomy at our comprehensive stroke center. Time metrics for patient presentation and care delivery were unchanged; however, rates of adherence for the quality measures dysphagia screening, early antithrombotic initiation, and early venous thromboembolism prophylaxis were reduced during the pandemic.

Conclusions:

In this regional analysis, we found decreasing telestroke consultations and ischemic stroke admissions, and reduced performance on stroke quality of care measures during the COVID-19 pandemic. Contrary to prior reports, we did not find an increase in thrombectomy nor decrease in clinical severity that might be expected if patients with milder symptoms avoided hospitalization.
Rethinking Consent for Stroke Trials in Time-Sensitive Situations
Authors: Goyal Mayank , Ospel Johanna Maria , Ganesh Aravind , Marko Martha , Fisher Marc
Published: February 2021

Informed consent is a key concept to ensure patient autonomy in clinical trials and routine care. The coronavirus disease 2019 (COVID-19) pandemic has complicated informed consent processes, due to physical distancing precautions and increased physician workload. As such, obtaining timely and adequate patient consent has become a bottleneck for many clinical trials. However, this challenging situation might also present an opportunity to rethink and reappraise our approach to consent in clinical trials. This viewpoint discusses the challenges related to informed consent during the COVID-19 pandemic, whether it could be acceptable to alter current consent processes under these circumstances, and outlines a possible framework with predefined criteria and a system of checks and balances that could allow for alterations of existing consent processes to maximize patient benefit under exceptional circumstances such as the COVID-19 pandemic without undermining patient autonomy.
Toxic effects of two commercial polybrominated diphenyl ethers on Artemia larvae at three developmental stages
Authors: Zhang Qingtian , Guo Sifan , Hu Guikun
Published: February 2021

Toxic effects of two commercial products, penta-BDE (DE-71) and octa-BDE (DE-79), on larvae of the brine shrimp, Artemia, were studied. Results showed that their toxic effects were related not only to the concentration and exposure time, but also to the developmental stage of Artemia. Newly hatched Artemia nauplii showed stronger tolerance than those at metanauplius stage or pseudoadult stage, while DE-71 showed a stronger toxic effect than DE-79 to some extent. Abnormal behaviour of Artemia larvae might occur within 12 h, and sometimes mortality rates increased quickly even if there was no death within 36 h. Both DE-71 and DE-79 showed significant influences on the body length of Artemia larvae within 24 h; the higher the concentration, the stronger the inhibition. As far as a toxic testing standard is concerned, further experimental studies on the selection of Artemia population and developmental stage are essential.
Ovarian development in the freshwater crab Goyazana castelnaui (H. Milne Edwards, 1853) (Brachyura, Trichodactylidae)
Authors: Freita F. R. V. , Pinheiro A. P. , Gregati R. A.
Published: February 2021

The aim of the present study was to describe the stages of ovarian development in the eubrachyuran crab Goyazana castelnaui through macroscopic and microscopic analyses and estimate size at physiological sexual maturity. Four ovarian development stages have been defined in the 60 G. castelnaui females that were analysed from the São Pedro River in the municipality of Ouricurí (semiarid region of the state of Pernambuco, Brazil), between November 2011 and October 2012. The crabs were collected and sent to the Semiarid Crustaceans Laboratory of the Cariri Regional University. Each specimen was measured. Ovaries were classified using a visual scale, removed with needle-nose pincers, fixed, and processed for microscopic analysis. Gonad stages were determined macroscopically using a staining process and were confirmed by histological analysis (initial, intermediate, mature and spawned). Size at physiological sexual maturity was determined to be 37.67 mm carapace width for females of this species.
New Private Media in French-Speaking West African Countries: Problems and Prospects
Authors: Marie-Soleil Frere
Published: February 2021

In this paper, we will try to take a closer look at the rise of the democratic transition in two French-speaking West African countries: Benin, often referred to as “the country where it all started”, and Niger that can be considered as one of the weak copies of the Beninese model. In the first part of the paper, we will try to show how the democratic experiment took place in both countries and how private and government-owned media came to play an active role in all main political changes. In the second part, we will take a closer look at the role of the new private written press in the democratic transition and try to mention the main problems facing both the press and the democracy implementation. Eventually, we will mention the recent political events that occurred in Benin and Niger, showing that the democratic process has generated very different outcomes.
At Men Dan Toch Echt Uit Kalebassen? Proto-Bantoe en de Domesticatie van Cucurbitacreae.
Authors: Bulkens Annelies
Published: February 2021

Eating out of Calabashes, Was it Reality? Proto-Bantu and the Domestication of Cucurbits

This paper examines the history of calabashes in the Bantu-world. Due to conservation problems of floral remains in tropical areas, no material traces of these fruits have been excavated untill now. The historical linguistic approach adopted in this paper, gives an overview of the evolution and history of different words signifying calabash and allows the formulation of some conclusions on agricultural history.
A new species of Amplisegmentum Webb (Diptera: Therevidae) from Venezuela
Authors: WINTERTON SHAUN L.
Published: February 2021

A new species of Amplisegmentum Webb (Therevidae: Therevinae) is described from Venezuela, a previously monotypic genus otherwise known only from Ecuador. A revised diagnosis of the genus and a key to species is presented.
Climatological Teleconnections with Wind Energy in a Midcontinental Region
Authors: Coburn Jacob
Published: February 2021

Variations in wind resources affect the reliability and feasibility of wind energy. At longer time scales, modes within the climate system and externally forced variability become important as the decadelong lifetimes of wind installations and upfront investment costs are considered. Understanding the influence of teleconnections may yield important insights for skillful seasonal predictions. In this study, several modes of variability, including the Arctic Oscillation (AO), El Niño–Southern Oscillation (ENSO), and the global surface solar flux, are assessed for their influence on wind energy anomalies in the upper Midwest (40°–52°N, 87°–105°W). Monthly wind energy is calculated using extrapolated 80-m wind fields from reanalysis data for the period 1980–2018. A multiple linear regression analysis is conducted for the monthly turbine energy output anomalies (TEOA) against the effects of synoptic patterns and pressure gradients, as well as the teleconnection indices, for each grid cell and season, yielding information on the spatial and temporal variations in influence throughout the region. The regression model indicated that each of the factors had significant influences on wind energy, although the effects varied spatially and by season. Periods of extremely low production are often embedded in prolonged declines over several months that were the result of a combination of synoptic variability and significant phases of the teleconnections such as large El Niño events, negative AO episodes, and volcanically induced reductions in surface solar flux. Monthly TEOA are found to vary by up to 37%, amounting to ±130 MW h and tens of thousands of dollars per turbine.
Exploring Stakeholder and Parent Perspectives of a County Response to Adolescent Vaping and E-Cigarette Use
Authors: Kurji Natasha , Koza Thomas , Sharp Amanda , Moore Kathleen
Published: February 2021

In the United States, regular cigarette use has steadily declined over the years; however, it has been met with an increase in vaping and e-cigarette use. In Tampa, Florida, this trend has been found especially prevalent among school-aged youth. To combat issues of substance use among youth and prevent criminalization for nonviolent crimes, school-age youth cited for use and possession of tobacco products in Hillsborough County were mandated to attend the Youth Tobacco Awareness Course (YTAC). The aim of this study was to investigate YTAC for its perceived effectiveness and usefulness in mitigating adolescent e-cigarette use. Classroom observations, parent focus groups, and program stakeholder interviews were conducted to comprehensively evaluate this program. Findings from this evaluation led to a deeper understanding of the barriers and facilitators to an effective course, the needs and perceptions of program stakeholders, as well as recommendations for improved future interventions.
Drink, Share, and Comment; Wait, What Did I Just Do? Understanding Online Alcohol-Related Regret Experiences Among Emerging Adults
Authors: Geusens Femke , Vranken Ilse
Published: February 2021

This study investigated the causes and coping strategies of regret of sharing alcohol-related content on social media. Semi-structured interviews were conducted among emerging adults who experienced regret of having shared either general alcohol references or drunken references ( n = 29, ages 19–25 years, M = 21.38, SD = 1.60). The most important cause of regret was a disruption of one’s online self-presentation. When delving deeper into the specific causes of online alcohol-related regret and how this content can disrupt the self-presentation, two overarching themes emerged: (a) content-related regret, and (b) audience-related regret. When examining the coping strategies, we found that emerging adults applied different strategies (a) to minimize their regret (e.g., delete the content), and (b) to avoid future regret (e.g., delete social media before going out). Implications for prevention are discussed.
Dermal Regeneration Template and Staged Skin Grafting for Extirpative Scalp Wound Reconstruction: A 14‐Year Experience
Authors: Maus Jacob C. , Hemal Kshipra , Khan Mija , Calder Bennett W. , Marks Malcolm W. , Defranzo Anthony J. , Pestana Ivo Alexander
Published: February 2021

Objective

Dermal regeneration template and staged split‐thickness skin grafting may mitigate the need for flap coverage of postoncologic scalp defects. This technique has been studied previously in small case series. We examine the effect of risk factors, surgical technique, irradiation, and dressing modalities on reconstructive outcomes in a highly comorbid patient cohort.

Study Design

Retrospective review.

Setting

Academic medical center.

Methods

Full‐ and partial‐thickness extirpative scalp wounds reconstructed with dermal regeneration template and staged skin grafting were reviewed over a 14‐year period. Stage 1 consisted of template application following burr craniectomy in cases lacking periosteum. Stage 2 consisted of skin grafting. Negative pressure wound therapy (NPWT) was variably used to support adherence.

Results

In total, 102 patients were analyzed (average age 74, mean follow‐up 18 months). Eighty‐one percent were American Society of Anesthesiologists class 3 or 4. Defect size averaged 56 cm2. Average skin graft take was 94.5% in full‐thickness wounds. Seven patients failed this method. Preoperative scalp irradiation was associated with major complication and delayed graft healing. Comorbidities, wound size, and burring were not associated with complication. Patients were more likely to heal with NPWT compared to bolster (hazard ratio, 1.67; 95% CI 1.01‐2.77; P =. 046). Time between stages was 6.6 days shorter when NPWT was applied (P <. 001).

Conclusion

Dermal template and staged skin grafting is a reliable option for postcancer scalp reconstruction in poor flap candidates. Radiotherapy is associated with adverse outcomes. Negative pressure wound therapy simplifies postoperative wound care regimens and may accelerate healing.
Challenges in the Delivery of Rural Otolaryngology Care During the COVID‐19 Pandemic
Authors: Losenegger Tasher , Urban Matthew J. , Jagasia Ashok J.
Published: February 2021

Though initially spared from the brunt of the COVID‐19 pandemic, rural areas in the United States have been ravaged by the disease. With a higher‐risk population at baseline and an already strained health care system, rural hospitals face severe challenges in delivering care during the pandemic. In otolaryngology specifically, there has been difficulty in ensuring patient access to care while maintaining safe environments for patients and staff. Partnership between academic medical centers and critical access rural hospitals is urgently needed to help improve care for vulnerable rural populations.
Synthesis and characterization of a chalcone-derived epoxy containing pyrazoline ring with excellent flame resistance
Authors: Zhang Yan-min-zi , Huang Meng-yao , Zhou Jun , Li Da-zhe , Lei Yi
Published: February 2021

Traditional epoxy resins are made by the reaction of petroleum-based bisphenol A and epichlorohydrin. The disadvantages of these petroleum-based epoxy including certain biological toxicity and flammability. To solve these problems, we first synthesized a diphenol compound 3,5-(4-hydroxyphenyl)-2-pyrazoline (TPP), which was prepared by condensation reaction of bio-based chalcone with hydrazine hydrate to replace standard petroleum-based bisphenol A. Then it was condensed with epichlorohydrin under alkaline condition to form a fully aromatic pyrazoline ring epoxy (TPP-EP). For further research, we use 4,4′-diaminodiphenylmethane (DDM) as the curing agent. When compared with bisphenol A epoxy resin (DGEBA/DDM), TPP-EP/DDM possessed a higher glass transition temperature (233°C vs. 176°C), and even showed that the residual carbon (in N2) and the storage modulus (at 30°C) increased by 201% and 74%, respectively. What’s more, TPP-EP/DDM system also had good inherent flame retardancy. The limiting oxygen index of TPP-EP/DDM was 33.1, reaching the V-0 level tested by UL-94. From the cone test, the THR, p-HRR, p-SPR and TSP values of TPP-EP/DDM systems also showed different degrees of reduction. Since TPP-EP contained tertiary amine active groups that could be used as a kind of catalytic curing agents for epoxy resins, thus the compound had certain self-curing properties. This work was of great significance for the synthesis of pyrazoline bio-based environmentally friendly flame-retardant epoxy resin.