bluuebunny/crossref_metadata_2025 huggingface dataset:
Analysis and Design of a Servomotor Operating on High-Pressure Compressed Gas
Authors: Reethof Gerhard
Published: February 2022

The analysis, design, and development of a high-performance gas servomechanism suitable for aircraft and missile applications are described. The flow-control valve consists of two upstream orifices of fixed areas and two differentially variable downstream orifices. The areas of the variable orifices are controlled by a simple electromagnetic actuator. The fluid motor consists of two single-acting self-lubricating pistons which actuate the rocker-arm load assembly through push rods. Design parameters were obtained from the results of an analog-computer design study. The predicted transient response agrees very well with the experimentally derived rise time of 4 millisec.
Heat-Transfer Rates to Crossflowing Mercury in a Staggered Tube Bank—I
Authors: Hoe R. J. , Dropkin D. , Dwyer O. E.
Published: February 2022

An experimental heat-transfer program has been under way for some time at the Brookhaven National Laboratory, the general purpose of which is to obtain and correlate heat-transfer coefficients for liquid metals flowing outside of tube banks. This paper covers one phase of the program; i.e., the measurement of heat-transfer coefficients for mercury flowing normal to a staggered tube bank. The factors studied were (a) linear velocity, (b) tube location in the bank, (c) circumferential variation of the local coefficient for a single tube, (d) type of contact, i.e., “wetting” versus “nonwetting,” and (e) pressure drop.
Effect of Internal Pressure on Flexibility and Stress-Intensification Factors of Curved Pipe or Welding Elbows
Authors: Rodabaugh E. C. , George H. H.
Published: February 2022

The flexibility and stress-intensification factors presently applied in piping-flexibility analysis to account for the behavior of curved pipe in bending have been derived from theories and tests with no internal pressure. Pressure tends to reduce the effect of these factors but in smaller and relatively thick-wall piping commonly used in the past the effect is of a low order and may be neglected; in larger diameter relatively thin-wall piping the effect is pronounced and significant. Using strain-energy methods the present paper develops a theory establishing the flexibility and stresses due to in-plane and out-of-plane bending including the effect of internal pressure, and proves its adequacy by means of carefully conducted tests. In a final step, the complex theoretical formulas are reduced to a simple and readily usable approximation.
Discussion on Safety-Factor Requirements for Supersonic Aircraft Structures
Authors: Goldman G. M.
Published: February 2022

This paper deals with the safety-factor aspects of design rather than any discussion of design-criteria conditions. It covers essential items concerning certain present safety-factor aspects, new problems caused by the advent of heated aircraft structures, and the ideas of Air Force engineers as to the procedure necessary to provide adequate safety reserves in the design of new high-speed aircraft.
Orifice-Metering Coefficients and Pipe Friction Factors for the Turbulent Flow of Lead-Bismuth Eutectic
Authors: Johnson H. A. , Hartnett J. P. , Clabaugh W. J. , Fried L.
Published: February 2022

Pipe friction factors and orifice-metering coefficients are reported for the turbulent flow of lead-bismuth eutectic and are found to be in satisfactory agreement with the results for water flow when compared on the usual dimensionless basis.
Testing Dynamically Loaded Bearings—II: A Diesel-Engine Bearing Test Machine
Authors: Snapp R. B. , Hersey M. D.
Published: February 2022

This paper describes an engine-bearing test machine consisting of a motor-driven modification of a commercially available diesel engine. The machine combines the advantages of engine operation with those of a standardized test machine. It was developed primarily for endurance testing of engine-bearing materials and design. A rating system is described for evaluating the extent of various kinds of failure elements so that bearings may be compared without testing them to destruction. Test results and the use of an oil-film-thickness indicator also are described briefly.
Estimating Partial-Load Performance of Large Reheat Turbine-Generator Units
Authors: Fulton S. D. , Morgan D. W. R.
Published: February 2022

This paper presents a short method for estimating partial-load heat rates of large reheat steam turbine-generator units from data at the guaranteed capability point.
Engineering the Eddystone Plant for 5000-Lb 1200-Deg Steam
Authors: Harlow J. H.
Published: February 2022

This paper presents a report on the problems encountered and the solutions developed in engineering a power plant with a single boiler supplying a turbogenerator set of 325,000 kw rating with throttle steam conditions of 5000 psi and 1200 F. A brief discussion is given of the co-operative method used, a short history of the supercritical pressure idea, and an abbreviated review of the significance of supercritical conditions. The paper is concerned with the problems of water conditioning and quality control, of piping materials and design requirements, of heat-cycle development, of pumping feedwater to the very high levels required, and of other miscellaneous plant-design situations. Companion papers discuss in great detail the boiler and turbine-design considerations.
Engineering the Eddystone Steam Generator for 5000-Psig, 1200-F Steam
Authors: Powell E. M.
Published: February 2022

This paper is presented as one of three describing the development of the Eddystone Station. Particular attention is given to the major engineering considerations in the design of the steam-generating unit. It includes a description of the unit and its control system with a review of the research program which was a necessary part of the project.
Transient Air Temperatures in a Duct
Authors: Rea S. E. , Ablow C. M.
Published: February 2022

Transient temperatures in a thin-walled duct carrying heated air are investigated experimentally and theoretically. The simplified theory applies to turbulent liquid or low-speed gas flow. The duct wall is shown to be an important heat reservoir.
Pressure Drop and Air-Flow Distribution in Gas-Turbine Combustors
Authors: Grobman J. S. , Dittrich R. T. , Graves C. C.
Published: February 2022

Generalized curves showing the combustor total pressure-loss coefficient and air-flow distribution for various geometric configurations and operating conditions were obtained from theoretical calculations. The results pertain to tubular turbojet combustors having (a) constant annulus and liner cross-sectional areas along the combustor axis, and (b) flush circular holes in the liner walls.
Nonhomogeneous Yielding of Steel Cylinders 1—Mild Steel
Authors: Steele M. C. , Eichberger L. C.
Published: February 2022

Experimental information on the mechanism of yield and the associated strains is presented for mild-steel cylinders (2:1 diameter ratio) overstrained by internal fluid pressure. A limited number of Lueders’ lines develop and propagate through the cylinder wall according to distinct patterns. The strains vary circumferentially in keeping with the nonhomogeneous mechanism of yield. Comparison with homogeneous plasticity theories shows good agreement for circumferential strains provided a correction is made for the material yield stress. Axial strains are essentially elastic. Creep under maintained constant load is discussed in relation to strain and Lueders’ line movement.
Information Center With Automatic Logger and Scanner—Neches Power Station, Gulf States Utilities Company
Authors: Reich J. A. , Gurney W. B.
Published: February 2022

Neches Power Station of the Gulf States Utilities Company in Beaumont, Texas, has six relatively small turbine-boiler units. After installing an information system (which includes alarms, scanners, and a logger), sufficient personnel were released to man new large modern units. The installation is expected to pay for itself in three years and to increase over-all plant economy. Hourly unit efficiencies are computed and recorded.
A Dynamic Performance Computer for Gas-Turbine Engines
Authors: Larrowe V. L. , Spencer M. M. , Tribus M.
Published: February 2022

Standard analog computing equipment is combined with electromechanical “map readers” made from modified X-Y plotters to form a gas-turbine-engine performance computer. The complete engine computer assembly is composed of a number of smaller assemblies, each of which represents a separate element of the engine. All of these smaller computers, working simultaneously, exchange and combine information to compute the performance of the entire engine. The computer can be made to represent any gas-turbine engine of any degree of complexity by merely adding the required additional engine element computers. It may be used to explore engine behavior, to obtain both steady-state and transient engine operating data, and to test various control systems.
Experimental Investigation of Critical Design Factors for Vane-Type Cyclones
Authors: Walker A. B. , Cole W. H.
Published: February 2022

Many of the so-called high-efficiency mechanical collectors in use today are of the multiple-tube vane type. A basic investigation has been made on the effects of tube size, inlet-vane design, and utilization of outlet-tube vanes on the performance of this type collector. The critical nature of these factors and methods for obtaining higher efficiency and gas flow is demonstrated. A comparison between predicted field results from laboratory tests and actual field results is presented, and the accuracy of specific laboratory techniques in predicting field performance indicated.
Compensation of Steady-State Flow Forces in Spool-Type Hydraulic Valves
Authors: Clark R. N.
Published: February 2022

Three heretofore unreported schemes for reducing the steady-state flow forces in spool-type hydraulic valves are described. Experimental data are presented which compare the steady-state flow-force characteristics of valves using each of these schemes to the characteristics of uncompensated valves.
Evidence That Rating of Perceived Exertion Growth During Fatiguing Tasks is Scalar and Independent of Exercise Mode
Authors: Meyer Hannah , Bruenig Jeena , Cortis Cristina , de Koning Jos J. , Doberstein Scott T. , Fusco Andrea , Mikat Richard P. , Porcari John P. , Wright Glenn , Foster Carl
Published: February 2022

Introduction:The relationship between the percentage of a fatiguing ambulatory task completed and rating of perceived exertion (RPE) appears to be linear and scalar, with a relatively narrow “window.” Recent evidence has suggested that a similar relationship may exist for muscularly demanding tasks.Methods:To determine whether muscularly demanding tasks fit within this “ambulatory window,” we tested resistance-trained athletes performing bench press and leg press with different loadings predicted to allow 5, 10, 20, and 30 repetitions and measured RPE (category ratio scale) at the end of the concentric action for each repetition.Results:There was a regular, and strongly linear, pattern of growth of RPE for both bench press (r = .89) and leg press (r = .90) during the tasks that allowed 5.2 (1.2), 11.6 (1.9), 22.7 (2.0), and 30.8 (3.2) repetitions for bench press and 5.5 (1.5), 11.4 (1.6), 20.2 (3.0), and 32.4 (4.2) repetitions for leg press, respectively.Conclusions:The path of the RPE growth versus percentage task fit within the window evident for ambulatory tasks. The results suggest that the RPE versus percentage task completed relationship is scalar, relatively linear, and apparently independent of exercise mode.
Initial uplift of the Qilian Shan, northern Tibet since ca. 25 Ma: Implications for regional tectonics and origin of eolian deposition in Asia
Authors: Lu Haijian , Sang Shengping , Wang Ping , Zhang Zhiyong , Pan Jiawei , Li Haibing
Published: February 2022

Sedimentary rocks in northern Tibet record uplift of the Tibetan Plateau and its potential connection with the evolution of the central Asian aridity, therefore offering a typical example of tectonic-climate linkage. The coarse-grained conglomeratic and sandy red beds of the Lulehe Formation (Fm.) in the northern Qaidam Basin (QB), northern Tibet, have long been held as synorogenic sediment accumulation. There is, however, a heated debate on its source area (the Qilian Shan, the east Kunlun Shan, or Qimen Tagh) and initiation age (ca. 52, 25.5, or ca. 21 Ma, respectively). These proposals lead to distinctly different mountain building processes of the giant Qilian Shan during the Cenozoic. One view argues that the Qilian Shan began to uplift substantially as a simultaneous far-field response to the India-Asia collision at 55–50 Ma. In contrast, others claim that significant rise of the Qilian Shan and thus northeastward expansion of the Tibetan Plateau did not occur until 19 or 12 Ma. Based on an updated magnetostratigraphic framework for the Cenozoic sediments in the northern QB, here we conducted structural, paleocurrent, pebble composition, zircon grain shape and surface texture, and detrital geochronological analyses of the Lulehe Fm., in the northern QB. The results indicate that the Lulehe Fm. was produced essentially by an initial rush of lithic clasts derived from the deformed Mesozoic sedimentary cover, which can be attributed to initial rise of the Qilian Shan since ca. 25 Ma. This finding leads additional credence to the argument that the onset of significant uplift of mountain ranges along the periphery of the plateau occurred nearly synchronously from the latest Oligocene through early Miocene. These prolonged elevated Mesozoic sediments covering the fold-thrust belts of the northern QB, on the other hand, may have acted as a sustained source of material for the Miocene eolian deposits in the western Chinese Loess Plateau.
Resonant Hybrid Metal–Dielectric Nanostructures for Local Color Generation
Authors: Ageev E. I. , Iudin V. A. , Sun Y. , Petrova E. A. , Kustov P. N. , Yaroshenko V. V. , Mikhailova J. V. , Gudovskikh A. S. , Mukhin I. S. , Zuev D. A.
Published: February 2022

Here, we experimentally and theoretically demonstrate a laser-induced change in local color based on the reshaping of gold–silicon asymmetric nanostructures. The evolution of scattering properties enabled by laser reshaping shows the potential of hybrid metal–dielectric nanostructures for color printing applications. The reshaping process can tune the resonance of the nanostructure in the wavelength range between 500 and 800 nm resulting in different colors of illuminated nanostructures. Moreover, the modeling of the scattering diagram of hybrid nanoparticles before and after femtosecond laser reshaping shows that color tuning is simultaneously accompanied by substantial reconfiguration of the distribution pattern for both peaks in the scattering spectrum.
On the Percolation Regime of the Bulk Transport of the Bi1.08Sn0.02Sb0.9Te2S Topological Insulator
Authors: Sakhin V. , Kukovitsky E. , Talanov Y. , Teitel’baum G. , Morgun L. , Borisov A. , Usoltsev A. , Pudalov V.
Published: February 2022

The formation of nanosized charge droplets in the bulk of a three-dimensional topological insulator Bi1.08Sn0.02Sb0.9Te2S was evidenced using electron spin resonance. Since electrons and holes are “locked” in these droplets far apart from each other, their participation in bulk conductivity is possible only due to thermal activation or to variable range hopping. Our transport measurements give evidence that at relatively high temperatures conduction follows the activation behavior with the activation energies which due to percolation may be much smaller than the half of the band gap. We also demonstrate that the variable range hoping replaces the activated transport at sufficiently low temperatures.
Softwood biochar and greenhouse gas emissions: a field study over three growing seasons on a temperate agricultural soil
Authors: Jiang Runshan W. , Mechler Meaghan A.A. , Oelbermann Maren
Published: February 2022

Agricultural activities contribute to greenhouse gas emissions, but agroecosystems can also mitigate emissions by adding recalcitrant carbon sources such as biochar to soil. Our goal was to understand if greenhouse gas emissions decrease in soil amended with manure and biochar (MN) or with manure, nitrogen fertilizer, and biochar (MNB) than soil amended with manure and N fertilizer (MN) over the longer term. We hypothesized that biochar reduces the release of labile carbon and reactive nitrogen from organic amendments and nitrogen fertilizer, thereby reducing CO2 and N2O emissions and that soil temperature, moisture, and nitrogen availability are the strongest predictors for intra- and inter-annual variation in greenhouse gas emissions. Over three growing seasons, biweekly measurements of CO2 and N2O emissions were similar (P < 0.05) among treatments. Although input of labile carbon and reactive nitrogen was highest in MN and MB, cumulative CO2 emissions were lowest (P < 0.05) in MNB. The availability of nitrogen from fertilizer caused greater cumulative N2O emissions (P < 0.05) in MN and MNB. We found that soil temperature, moisture, and nitrogen availability regulated intraannual variability (P < 0.05) of CO2 and N2O emissions in all treatments, where emissions were greatest (P < 0.05) in the spring followed by summer and autumn. We accepted our hypothesis and concluded that, for cumulative emissions, biochar reduces the release of labile carbon and reactive nitrogen, but we rejected this hypothesis for biweekly emissions. We also concluded and accepted our hypothesis that soil temperature, moisture, and nitrogen availability regulated intraannual variation of CO2 and N2O in all treatments.
Policy Note: Water Affordability and Accessibility in Baltimore, Maryland
Authors: Hanke Steve H. , Arena Christopher
Published: February 2022

Water system revenue losses, inefficiency, mismanagement, lack of productivity, and federal mandates are rapidly escalating the cost of water and wastewater for Baltimore consumers. Baltimore’s water and wastewater systems are municipally owned and poorly managed by Baltimore City. Due to a lack of maintenance, these systems are plagued by an immense number of leaks, main breaks, and sewage backups. In addition, the billing system has a long history of errors. The overall deterioration of the systems, inadequate capital management, and operational problems are symptomatic of the fact that the Baltimore City Department of Public Works lacks proper accounts, including a balance sheet. Despite these glaring flaws, the systems have been politicized and are now protected by an amendment to the Baltimore City Charter that prohibits the assistance of private enterprise and markets in addressing Baltimore’s endemic water and wastewater problems by tapping the competency and skills available in the private marketplace. In order to reverse the politicization of Baltimore’s water system, which will only make operation and capital mismanagement problems worse as well as increase costs for the citizens of Baltimore, the charter amendment must be eliminated, allowing for the private provision of infrastructure and its maintenance. We recommend that this private provision is based on the centuries-old tried and tested French model.
Comparison of groundwater composition from the Monturaqui and Punta Negra Basins, northern Chile: implications for porphyry copper exploration
Authors: Rissmann C. W. F. , Leybourne M. I. , Benn C. , Kidder J. A. , Pearson L. K.
Published: February 2022

Groundwaters recovered from the Salar de Punta Negra and Monturaqui basins in the Atacama Desert of northern Chile exhibit distinctly different isotopic, major, trace, and porphyry copper elemental compositions related to contrasting morphostructural, geochemical, and hydrodynamic settings. Comparison of these distinct groundwater signatures with groundwaters from known porphyry copper deposits (Salar de Hamburgo and Spence Deposit), can be used to determine if either basin might be prospective for porphyry copper mineralization. Groundwaters within the Punta Negra Basin exhibit geochemical characteristics consistent with other closed basin settings throughout the arid Andes. Elemental and isotopic compositions within the Punta Negra Basin reflect closed basin evaporitic processes consistent with the hyperarid, volcanic setting of the central Andes. Pathfinder metals and isotopic compositions are not consistent with porphyry copper type mineralization as described for groundwaters within the Salar de Hamburgo Basin, and the Spence Deposit. Within the Monturaqui Basin the geochemical composition of groundwaters are characteristic of diffuse hydrothermal activity. Sulfur isotopic composition within the waters of the northern Monturaqui Basin exhibit

δ

34
S
CDT
isotopic signatures that fall within the range for sulfide mineralization as reported for groundwaters in and around the Spence Deposit and the Salar de Hamburgo. However, porphyry copper related elements within the Monturaqui Basin are impoverished relative to groundwaters of the Spence and Escondida Deposit. Such impoverishment in porphyry related elements, taken in conjunction with enriched

δ

13
C
PDB
compositions, elevated groundwater temperatures, groundwater compositions dominated by HCO
3
, SO
4
, and Si, and the proximity of the Monturaqui Basin to the current magmatic arc are consistent with a volcanic hydrothermal origin. In summary, the groundwater geochemistry of the Monturaqui and Punta Negra Basins are not indicative of porphyry copper-type mineralization.

Thematic collection:
This article is part of the Hydrochemistry related to exploration and environmental issues collection available at:
https://www.lyellcollection.org/cc/hydrochemistry-related-to-exploration-and-environmental-issues
Generating Relevant and Informative Questions for Open-Domain Conversations
Authors: Ling Yanxiang , Cai Fei , Liu Jun , Chen Honghui , de Rijke Maarten
Published: February 2022

Recent research has highlighted the importance of mixed-initiative interactions in conversational search. To enable mixed-initiative interactions, information retrieval systems should be able to ask diverse questions, such as information-seeking, clarification, and open-ended ones.
question generation (QG)
of open-domain conversational systems aims at enhancing the interactiveness and persistence of human-machine interactions. The task is challenging because of the sparsity of question generation (QG)-specific data in conversations. Current work is limited to single-turn interaction scenarios. We propose a

context-enhanced neural question generation

(CNQG)
model that leverages the conversational context to predict question content and pattern, then perform question decoding. A hierarchical encoder framework is employed to obtain the discourse-level context representation. Based on this, we propose
Review
and
Transit
mechanisms to respectively select contextual keywords and predict new topic words to further construct the question content. Conversational context and the predicted question content are used to produce the question pattern, which in turn guides the question decoding process implemented by a recurrent decoder with a joint attention mechanism. To fully utilize the limited QG-specific data to train our question generator, we perform multi-task learning with three auxiliary training objectives, i.e., question pattern prediction,
Review
, and
Transit
mechanisms. The required additional labeled data is obtained in a self-supervised way. We also design a weight decaying strategy to adjust the influences of various auxiliary learning tasks. To the best of our acknowledge, we are the first to extend the application of QG to the multi-turn open-domain conversational scenario. Extensive experimental results demonstrate the effectiveness of our proposal and its main components on generating relevant and informative questions, with robust performance for contexts with various lengths.
Fsp27 plays a crucial role in muscle performance
Authors: Slayton Mark , Balakrishnan Bijinu , Gupta Abhishek , Jobe Scott , Puri Ishika , Neely Savannah , Tamori Yoshikazu , Russ David W. , Yildirim Gozde , Yakar Shoshana , Sharma Vishva M. , Puri Vishwajeet
Published: February 2022

This is the first study identifying Fsp27 as a novel protein associated with muscle metabolism. The fsp27-knockout model shows that Fsp27 plays a role in muscular-fat storage, muscle endurance, and muscle strength, which ultimately impacts limb movement. In addition, our study suggests a potential metabolic paradox in which FSP27-knockout mice presumed to be metabolically healthy based on glucose utilization and oxidative metabolism are unhealthy in terms of exercise capacity and muscular performance.
TAZ is important for maintenance of the integrity of podocytes
Authors: Chen Jianchun , Wang Xiaoyong , He Qian , Harris Raymond C.
Published: February 2022

Podocytes play an important role in maintaining the integrity of the structure and function of the kidney. We observed that mice with selective deletion of transcriptional coactivator with PDZ-binding motif (TAZ) in podocytes developed proteinuria. TAZ is constitutively active and critical for expression of synaptopodin, zonula occludens-1, and zonula occludens-2 in podocytes. The findings of this study implicate TAZ as an important mediator of podocyte structural integrity and provide further insights into the role of Hippo-Yes-associated protein/TAZ in podocyte biology.
Drought Analysis Using Standardized Evapotranspiration and Aridity Index at Bilate Watershed: Sub-Basins of Ethiopian Rift Valley
Authors: Haile Bereket Tesfaye , Bekitie Kassahun Ture , Zeleke Tadesse Terefe , Ayal Desalegn Yayeh , Feyisa Gudina Legese , Anose Fikiru Abiko
Published: February 2022

In Ethiopia, more prevalent drought happenings have been documented in the past century. The problem has gradually expanded from the north to the rest parts with deepened intensity. The study aimed to examine the magnitudes of spatiotemporal patterns of drought at the Bilate watershed from 1981 to 2016. Monthly rainfall and temperature data were used for the analysis. The Standardized Evapotranspiration Indexes (SPEI) at SPEI-03 and SPEI-12 timescales were applied to evaluate the drought patterns. Among different drought indices, the SPEI is the most valuable and preferred Index for drought studies. The SPEI method considers the role of temperature than other indices to compare drought in time and space. The Mann–Kendall test was used for trend analysis. Accordingly, the result revealed that 1988–2016 were years of continuous drought events in both timescales with (SPEI = −2.5 to −1.2) drought value. Drought severity and frequency were highly detected at Wulberag areas (SPEI: −2.5). Durame, Angacha, and Alaba experienced increasing drought trends (Z = −1.96−1.6) and Welayita Sodo is Z = −0.07−0.03. Bilate-Tena and Hossana area of the watershed were less affected by drought than other areas. Spatially, the drought occurrences were observed in all areas of the watershed with varying magnitude. In the SPEI-12 timescale, more frequent drought occurrences were observed than SPEI-03. It was found that severe drought was observed in 1987, 1993/94, 2000–2005, and 2010. Moreover, the watershed experienced an Aridity Index (AI) of 0.43 (43%) and was subjected to potential high evapotranspiration (PET). The highest PET was observed at Bilate-Tena, Angacha, Hosanna, Wulberag, Alaba, Welayita Sodo, and Durame (151.6, 119.6, 119.3, 140.8, 142, 127.5, and 125.7 mm/year, respectively. Hence, the finding of this study could initiate a further inquiry on drought risk management, early warning responses, and local scale planning.
Recent Advances on Bacterial Cellulose-Based Wound Management: Promises and Challenges
Authors: Moradpoor Hedaiat , Mohammadi Hossein , Safaei Mohsen , Mozaffari Hamid Reza , Sharifi Roohollah , Gorji Pourya , Sulong Abu Bakar , Muhamad Norhamidi , Ebadi Mona
Published: February 2022

Wound healing is a therapeutic challenge due to the complexity of the wound. Various wounds could cause severe physiological trauma and bring social and economic burdens to the patient. The conventional wound healing treatments using bandages and gauze are limited particularly due to their susceptibility to infection. Different types of wound dressing have developed in different physical forms such as sponges, hydrocolloids, films, membranes, and hydrogels. Each of these formulations possesses distinct characteristics making them appropriate for the treatment of a specific wound. In this review, the pathology and microbiology of wounds are introduced. Then, the most recent progress on bacterial cellulose- (BC-) based wound dressing discussed and highlighted their antibacterial and reepithelization properties in vitro and in vivo wound closure. Finally, the challenges and future perspectives on the development of BC-based wound dressing biomaterials are outlined.
Nauclea orientalis (L.) Bark Extract Protects Rat Cardiomyocytes from Doxorubicin-Induced Oxidative Stress, Inflammation, Apoptosis, and DNA Fragmentation
Authors: Sandamali Jayasinghe A. N. , Hewawasam Ruwani P. , Jayatilaka Kamani A. P. W. , Mudduwa Lakmini K. B.
Published: February 2022

The therapeutic efficacy of anthracycline antibiotic, doxorubicin (Dox), is hampered due to the dose-dependent cardiotoxicity. The objective of the study was to explore the counteraction of aqueous bark extract of Nauclea orientalis in Dox-induced cardiotoxicity in Wistar rats. The acute and subchronic toxicity study performed with 2.0 g/kg of the plant extract revealed biochemical and haematological parameters to be within the physiological range, and no histological alterations were observed in any organs isolated. Screening of plant extract for the protection of the myocardium from Dox-induced oxidative stress, inflammation, and apoptosis was performed on five groups of rats: control, plant extract control, Dox control (distilled water (D.H2O) 2 weeks + on the 11th day single injection of Dox, 18 mg/kg), plant + Dox (2.0 g/kg plant extract 2 weeks + on the 11th day Dox, 18 mg/kg), and positive control, dexrazoxane. A significant increase in cardiac biomarkers and lipid peroxidation (

p
<
0.001

) and a significant decrease in antioxidant parameters (

p
<
0.001

) were observed in the Dox control group. All these parameters were reversed significantly (

p
<
0.05

) in the plant-pretreated group. The histopathological assessment of myocardial damage provided supportive evidence for the biochemical results obtained. Inflammatory markers, myeloperoxidase, expression of TNFα and caspase-3, and DNA fragmentation (TUNEL positive nuclei) were significantly elevated (

p
<
0.05

), and expression of Bcl-2 was significantly decreased (

p
<
0.05

) in the Dox control; however, all these parameters were significantly reversed in the plant extract-treated group. In conclusion, the aqueous bark extract of Nauclea orientalis (2.0 g/kg) has the ability to attenuate the Dox-induced oxidative stress, inflammation, apoptosis, and DNA fragmentation in Wistar rats.
Luteolin Alleviates Epithelial-Mesenchymal Transformation Induced by Oxidative Injury in ARPE-19 Cell via Nrf2 and AKT/GSK-3β Pathway
Authors: Chen Lan , Zhu Yanqing , Zhou Jie , Wu Rui , Yang Ning , Bao Qinbin , Xu Xinrong
Published: February 2022

Oxidative stress plays a critical role in age-related macular degeneration (AMD), and epithelial-mesenchymal transition (EMT) is involved in this process. The aim of this study was to investigate the protective effects of luteolin, a natural flavonoid with strong antioxidant activity, on H2O2-induced EMT in ARPE-19 cells. ARPE-19 cells were incubated with H2O2 at 200 μΜ to induce oxidative stress-associated injury. Cell viability assay showed that luteolin at 20 and 40 μM significantly promoted cell survival in H2O2-treated ARPE-19 cells. Luteolin also markedly protected ARPE-19 cells from H2O2-induced apoptosis. Cell migration assay presented that luteolin significantly reduced H2O2-induced migration in APRE-19 cells. EMT in ARPE-19 cells was detected by western blotting and immunofluorescence. The results showed that H2O2 significantly upregulated the expression of α-SMA and vimentin and downregulated the expression of ZO-1 and E-cadherin, while cells pretreated with luteolin showed a reversal. Meanwhile, the assessment of effects of luteolin on the Nrf2 pathway indicated that luteolin promoted Nrf2 nuclear translocation and upregulated the expressions of HO-1 and NQO-1. In addition, luteolin significantly increased the activities of SOD and GSH-PX and decreased intracellular levels of ROS and MDA in H2O2-treated ARPE-19 cells. Meanwhile, we observed that the expression of TGF-β2, p-AKT, and p-GSK-3β was upregulated in H2O2-treated ARPE-19 cells and downregulated in luteolin-treated cells, revealing that luteolin inhibited the activation of the AKT/GSK-3β pathway. However, these effects of luteolin were all annulled by transfecting ARPE-19 cells with Nrf2 siRNA. Our current data collectively indicated that inhibition of luteolin on EMT was induced by oxidative injury in ARPE-19 cell through the Nrf2 and AKT/GSK-3β pathway, suggesting that luteolin could be a potential drug for the treatment of dry AMD.
Model Analysis of Sandstone Tunnel Cracking Based on Fracture Mechanics Theory and Sensor Testing Technology Research
Authors: Jin Hu , Gao Bo , Shen Yusheng
Published: February 2022

In this paper, we survey sandstone tunnels using sensor testing technology and conduct an in-depth analysis and research on the model of sandstone tunnel cracking based on the theory of fracture mechanics. This paper systematically investigates the static mechanical properties, energy evolution and distribution law, acoustic emission monitoring, and digital image correlation methods of intact and jointed rock chamber enclosures (including parallel jointed rock chamber enclosures and cross jointed rock chamber enclosures) under static loads, based on physical simulation test methods and combined with other technical means such as acoustic emission monitoring and digital image correlation methods. In this paper, the effects of parallel and cross-joint angles on the static mechanical properties, energy evolution and distribution, acoustic emission variability, progressive destabilization, and their mechanisms are compared and analyzed. This paper takes fiber Bragg grating (FBG) sensing theory and technology research as a breakthrough, relies on major underground engineering geohazard model tests, and proposes a grating spectral reconstruction theory based on the wavelength position constraint of the spectral center and its improvement based on an in-depth analysis of the influence of fiber grating intrinsic parameters and strain distribution on the reflection spectral properties. Based on an in-depth analysis of the influence of spectral center wavelength location and strain distribution on the reflectance spectral properties, we propose the grating spectral reconstruction theory based on the spectral center wavelength location constraint and its improved genetic algorithm optimization method; realize the fast and accurate identification and rejection of the melancholy effect of fiber grating; propose the sensor numerical simulation optimization design method; develop the high sensitivity seepage pressure sensor, new strain sensor, target flow sensor, microdisplacement sensor, and multipoint displacement sensor; and build a large capacity, multi-parameter fiber grating real-time monitoring network.
Electroacupuncture Alleviates Visceral Hypersensitivity in IBS-D Rats by Inhibiting EGCs Activity through Regulating BDNF/TrkB Signaling Pathway
Authors: Zhao Ying , Jiang Hui-ling , Shi Yu , Zhang Wei , Zhang Lei-xiao , Hou Yu-jun , Yang Zuo-qin , He Bao-yu , Liang Fan-rong , Zheng Qian-hua
Published: February 2022

Objective. To determine whether electroacupuncture (EA) could alleviate visceral hypersensitivity in diarrhea-predominant irritable bowel syndrome (IBS-D) rats by inhibiting EGCs activity via the BDNF/TrkB signaling pathway. Methods. Sprague Dawley rats were randomly divided to a control group (n = 8) and a model preparation group (n = 32), which received Senna solution by gavage and CUMS (chronic unpredictable mild stress) for 14 consecutive days and was further divided to a Model group, an EA group (only electroacupuncture), an EA + TrkB agonist group (electroacupuncture and TrkB), and an EA + DMSO group (electroacupuncture and DMSO, n = 8 for each). Rats in the three EA groups were acupunctured at ST25, ST36, and LR3 for 20 min every day for 14 days. Abdominal withdrawal reflex (AWR) was used to quantify visceral sensitivity; reverse transcription polymerase chain reaction (RT-PCR) and double immunofluorescent staining were used to detect the colocalized expression of GFAP/BDNF and GFAP/TrkB. Western Blot (WB) was used to detect the expression of PLC and SP in the colon. Flow cytometry was used to detect the expression of Ca2+. Results. EA effectively alleviated visceral hypersensitivity in IBS-D rats (

P
<
0.05

). Compared to the control group, the expression of BDNF, TrkB, PLC, SP, and Ca2+ and the colocalized expression of GFAP/BDNF and GFAP/TrkB increased in the Model group (

P
<
0.05

), while all these parameters decreased in the EA group following EA intervention (

P
<
0.05

). In addition, no significant difference was found between the EA + TrkB agonist group and the control group (

P
>
0.05

). Conclusions. EA alleviates visceral hypersensitivity of IBS-D rats possibly by inhibiting the activity of EGCs through the BDNF/TrkB-PLC-Ca2+ signaling pathway in the colon.
Topological Structures via Bipolar Hypersoft Sets
Authors: Musa Sagvan Y. , Asaad Baravan A.
Published: February 2022

In this article, we introduce bipolar hypersoft topological spaces over the collection of bipolar hypersoft sets. It is proven that a bipolar hypersoft topological space gives a parametrized family of hypersoft topological spaces, but the converse does not hold in general, and this is shown with the help of an example. Furthermore, we give a condition on a given parametrized family of hypersoft topologies, which assure that there is a bipolar hypersoft topology whose induced family of hypersoft topologies is the given family. The notions of bipolar hypersoft neighborhood, bipolar hypersoft subspace, and bipolar hypersoft limit points are introduced. Finally, we define bipolar hypersoft interior, bipolar hypersoft closure, bipolar hypersoft exterior, and bipolar hypersoft boundary, and the relations between them, differing from the relations on hypersoft topology, are investigated.
The Safety and Effectiveness of Melphalan-Based Intra-Arterial Chemotherapy for Retinoblastoma: An Updated Single-Arm Systematic Review and Meta-Analysis
Authors: Cao Yang , Zhou Mi , Tian Min , Lv Hong-bin
Published: February 2022

Melphalan-based intra-arterial chemotherapy was considered an innovative treatment for retinoblastoma patients because high rates of globe salvage could be obtained. Now it has been widely applied for primary or secondary treatment of retinoblastoma. This meta-analysis summarizes the most up-to-date evidence regarding the safety and effectiveness of melphalan-based intra-arterial chemotherapy in the treatment of retinoblastoma. The authors searched PubMed, EMBASE, and the Web of Science electronic databases for studies investigating the safety and effectiveness of melphalan-based intra-arterial chemotherapy in the treatment of retinoblastoma. Studies reporting outcomes and complications of melphalan-based intra-arterial chemotherapy for the treatment of retinoblastoma patients would be included. A total of 33 observational studies that involved 1900 patients and 2336 eyes were included. The overall globe salvage rate was 79.6% (773/971 eyes, 0.74 [95% CI: 0.66, 0.80]) for patients treated with IAC as primary therapy in 28 studies. The overall globe salvage rate was 66.4% (923/1391 eyes, 0.68 [95% CI: 0.60, 0.76]) for patients treated with IAC as secondary therapy in 25 studies. The most common ocular complications were retinopathy (32%) and palpebral edema (29.7%). The most common systemic complications were nausea/vomiting (20.9%). The overall metastasis rate was 1.1% (21/1793 patients, 0.038 [95% CI: 0.020, 0.038]). Twenty-nine studies that involved 1783 patients reported the mortality and the overall mortality was 1.5% (26/1783 patients, 0.029 [95% CI: 0.020, 0.048]). Our meta-analysis showed that melphalan-based IAC treatment was an option for retinoblastoma patients with acceptable efficacy according to retrospective studies. Further high-quality randomized control trials are necessary to provide more accurate and reliable results.
Research on the Construction of College Football Classroom Practice Teaching System Model Based on Big Data Analysis
Authors: Zhang Bo , Ren Wei
Published: February 2022

With the rapid development of information technology, the traditional single classroom teaching and passive learning methods of students can no longer meet the needs of all-round development of college students, and its urgent need to integrate with information technology. This article is aimed at the problem of lagging feedback on training results in the traditional teaching model, teachers’ active control, students’ passive obedience, ignoring the development of students’ personality in college football classrooms, and the inability to carry out personalized tracking and quantitative improvement of the training process of students’ related abilities. We constructed a college football classroom practice teaching system model based on big data analysis from the perspectives of establishing big data teaching resources, and implementing personalized resource recommendation, optimizing the traditional teaching process, integrating quantitative training, measurement and recording, implementing quantitative intervention, etc. Colleges and universities have carried out experimental observations. Through continuous observation and comparison, it is found that college football classroom practice teaching under big data is more conducive to improving students’ football skills and theoretical level than traditional teaching. This model makes full use of the advantages of big data and the combination of practical teaching methods, which can bring students a different learning experience and obtain good teaching effects. It has guiding and reference significance for college football practical teaching.
Elucidating Antiangiogenic Potential of Rauwolfia serpentina: VEGFR-2 Targeting-Based Molecular Docking Study
Authors: Abuzenadah Adel M. , Al-Sayes Fatin , Mahafujul Alam Syed Sahajada , Hoque Mehboob , Karim Sajjad , Hussain Ibtessam M. R. , Tabrez Shams
Published: February 2022

Angiogenesis plays a critical role in tumorigenesis as it provides the necessary blood supply to the newly grown solid tumor. It helps maintain the tumor microenvironment, promotes tumor development, progression, and metastasis. The vascular epithelial growth factor (VEGF), interacting with the tyrosine kinase receptor VEGFR-2 on endothelial cells, exerts its proangiogenic activity. Hence, targeting the VEGFR-2 signaling is considered a promising strategy to inhibit angiogenesis and thus cancer treatment. This study aims to identify the bioactive compounds derived from the medicinal herb Rauwolfia serpentina that effectively binds with VEGFR-2. The bioactive compounds of R. serpentina were first screened for their physicochemical properties using the DataWarrior program (version 5.5.0). Finally, 17 compounds that obeyed Lipinski’s rule of five and showed good drug-likeness were selected for molecular docking studies. Molecular docking results showed that the ligands ajmalicidine, 1, 2-dihydrovomilenine, rauwolscine, yohimbine, ajmaline, and papaverine interact strongly with the target VEGFR-2 receptor. Hydrogen bonds and hydrophobic interactions stabilized the interactions of these compounds with VEGFR-2. These compounds showed favourable drug-like properties and possess no significant toxicity. Therefore, the findings of this study indicate that the compounds derived from R. serpentina can be considered for the development of antiangiogenic drug candidates by targeting VEGFR-2.
Research on Immersion Teaching Method Based on 5G +XR Technology and Reinforcement Learning Model
Authors: Xie Xueqing
Published: February 2022

The traditional teaching mode is difficult to meet the needs of modern teaching development because of its single teaching method and insufficient utilization of resources. With the in-depth application of 5G and XR technology in the field of education, the teaching mode based on 5G + XR has become a research hotspot of educational informatization. Therefore, this paper proposed an immersive teaching method based on 5G + XR technology and reinforcement learning model. By analyzing the characteristics and advantages of 5G technology in the field of teaching, this paper expounded that 5G technology not only had an important impact on the reform of modern teaching mode, but also can promote the development of immersive teaching. In addition, based on the analysis of XR teaching theory and its significance, an immersive XR teaching design method based on reinforcement learning model was proposed, and the working principle of immersive XR teaching system and the architecture method of teaching space were given. Finally, the construction scheme of immersive teaching scene based on 5G + XR and the design idea of immersive XR teaching method were put forward. The experiment showed that the immersive XR teaching method proposed in this paper was better than the traditional teaching mode, whether it was the students' learning effect of knowledge or their participation and experience in learning, which also verified that the method proposed in this paper had certain feasibility and superiority. The immersion teaching method based on 5G + XR proposed in this paper can provide a reference for the reform and development of modern education and teaching mode.
Fitting the Relaxation Modulus of Viscoelastic Materials Based on the IoT-Supported Mathematics Algorithm
Authors: Wan Lunlun , Lin Fuyan
Published: February 2022

In this paper, the theory of viscoelastic material relaxation modulus testing, testing method, and material relaxation modulus parameter solution method is studied. Based on the IoT sensor test devices and the Hertzian mathematics theory, the relationship between the compression amount, pressure, and relaxation modulus of a rigid spherical indenter pressed into a flat viscoelastic material is studied. In combination with the Boltzmann superposition principle, the relaxation modulus test method and theory for viscoelastic materials are proposed. A good fitting curve was obtained to solve the relaxation modulus parameters of various materials under the three-element Maxwell model. The experimental setup and the results of the parameter fitting were analyzed to verify the feasibility and accuracy of the results.