bluuebunny/crossref_metadata_2025 huggingface dataset:
Membrane and Bending Analysis of Axisymmetrically Loaded Axisymmetrical Shells
Authors: Horvay G. , Clausen I. M.
Published: June 2021

Shell formulas are given which are applicable to engineering design.
Further Problems in Orthotropic Plane Stress
Authors: Conway H. D.
Published: June 2021

A solution is given for the infinite orthotropic plate containing an elliptical hole, the plate being subjected to tension at infinity and the axes of the hole and the direction of the tension inclined at arbitrary angles to the principal axes of orthotropy.
Buckling of Sandwich Cylinders Under Combined Compression, Torsion, and Bending Loads
Authors: Wang C. T. , Vaccaro R. J. , De Santo D. F.
Published: June 2021

A theoretical investigation is carried out on the buckling of sandwich cylinders under combined compression, torsion, and bending loads. The governing differential equation is solved by using Galerkin’s method. The interrelationship obtained between the critical loads is plotted in the form of nondimensional interaction curves. In the limiting cases of axial compression alone, torsion alone, bending alone, and combined bending and axial compression, the results agree with those obtained previously (1–3).
Shortcomings of Present Methods of Measuring and Simulating Vibration Environments
Authors: Morrow C. T. , Muchmore R. B.
Published: June 2021

This paper concerns itself with the problem of measuring a vibration environment to be encountered by a delicate instrument or electronic device in the field and of attempting to simulate the vibration in laboratory test as a check on the reliability of the design.
The Extended Theory of the Viscous Vibration Damper
Authors: Lewis F. M.
Published: June 2021

The paper extends the theory of the Viscous Vibration Damper either tuned or untuned to multimass systems and shows how an optimum damper can be designed for any installation. Special formulas are derived for the two mass plus damper systems.
Forced Vibrations of a Body on an Infinite Elastic Solid
Authors: Arnold R. N. , Bycroft G. N. , Warburton G. B.
Published: June 2021

The paper considers the forced vibration of a rigid body resting on a homogeneous elastic medium of infinite surface area and constant depth which may be finite or infinite. Four modes of vibration for a body with a circular base are investigated; (a) vertical translation, (b) torsion, (c) horizontal translation, (d) rocking. For a semi-infinite medium the amplitude response can be obtained for any mass in terms of known constants of the system and two fundamental functions f1 and f2, which depend only on the exciting frequency and the properties of the medium. Close approximations to these functions have been evaluated for each mode. Experiments on an elastic model are described, the results of which are in good agreement with theoretical prediction. The behavior of a stratum of infinite area is more complex since functions f1 and f2 also depend on stratum depth. These functions have been evaluated for the torsional mode only, experimental results being given for the other modes.
The Statistical Theory of Size and Shape Effects in Fatigue
Authors: McClintock F. A.
Published: June 2021

Fatigue specimens are considered in which the stress amplitude is constant with respect to time but falls off parabolically along the length of the specimen from the point of maximum stress. From assumptions regarding the local variability in the strength of the material, equations are derived relating the scatter in cycles to failure to the scatter in position of failure. The effect of specimen size is determined for these two types of scatter, as well as for the average life. It is found that the shape of the distribution function does not affect seriously the relation between scatter in cycles to failure and scatter in position of failure. The size effect, however, is markedly influenced by the shape of the distribution function. A modification is suggested to make the results applicable to tests to determine the endurance limit, where the stress amplitude is a variable.
Large Deflection Analysis for a Plate Strip Subjected to Normal Pressure and Heating
Authors: Williams M. L.
Published: June 2021

Large deflection analysis is carried out to determine the deflections and membrane stresses for an infinite strip when subjected to pressure and temperature variations across the width of the strip with the end points fixed in space. Results are graphed for both clamped and simply supported edge conditions in the case of uniform temperature T0, and uniform pressure p0. The calculations also include the possible thermal buckling deflections. In the limit case of a membrane of width b and thickness h, subjected to this loading condition, the central deflection w0 is determined from the simple relation [ ( w 0 / h ) 2 - 3 8 ( 1 + ν ) ( b / h ) 2 α T 0 ] ( w 0 / h ) = p 0 b 4 / ( 256 D h )
Aerodynamic Interference of Cascade Blades in Synchronized Oscillation
Authors: Chang Chieh-Chien , Chu Wen-Hwa
Published: June 2021

The failure of a compressor is sometimes due to flutter of the blades. Essentially, this problem is equivalent to a cascade in oscillation. The present analysis is to find the aerodynamic load on cascade in synchronized harmonic oscillations, pitching, and flapping. Conformal mapping is used. Two characteristic parameters are involved in the force and moment. One is μ which is related to the gap-chord ratio. The other is k which is known as reduced frequency. The main results are expressed in terms of these two parameters. Most can be reduced to closed form. The rest are given in graphs. The wake interference involves one new function C(μ,k) which is related to a ratio of two hypergeometric functions and which reduces to Theodorsen’s function C(k) in the limit of infinite gap. In a certain range of frequency and gap-chord ratio, the analysis shows quantitatively that single-oscillation airfoil theory may lead to inaccurate estimation of interference effect between blades.
Torsion of Circular Shafts of Variable Diameter
Authors: Abbassi M. M.
Published: June 2021

By using spherical polar co-ordinates, the stress function for circular shafts of variable diameter is expressed in terms of the Legendre associated functions of the second order. It is obtained for various curves forming the generating surface of the shaft.
Thin Circular Conical Shells Under Arbitrary Loads
Authors: Hoff N. J.
Published: June 2021

Equations defining the displacements of the median surface of a conical shell under arbitrary loads are developed. In their derivation only the essential parts of the strain energy are considered and three simultaneous partial differential equations are obtained through the use of the variational calculus. When the minimum radius of curvature of the median surface of the cone is made to approach a constant value, the cone goes over into a cylinder. At the same time the equations here developed for the cone are transformed into the Donnell equations of the theory of cylindrical shells. It is shown how eigenfunctions of the homogeneous equations can be constructed and how particular solutions can be found for any arbitrary loading.
Bending Creep and Its Application to Beam-Columns
Authors: Hu L. W. , Triner N. H.
Published: June 2021

A procedure for evaluating the creep deflection of members subjected to bending moment is suggested. The application of the suggested procedure to beam-columns is given. For checking the validity of the proposed method, an investigation on the creep behavior of beam-columns of magnesium alloy FS1-F at 260 F was conducted. The comparison of the experimental results with the theoretical predictions was found satisfactory.
Effect of an Acoustic Medium on the Dynamic Buckling of Plates
Authors: DiMaggio F. L.
Published: June 2021

The effect of a surrounding fluid on the dynamic buckling of an elastic plate under suddenly applied compressive stresses in its middle plane is studied. Assuming an infinite plate supported at regular intervals and a semi-infinite acoustic medium, exact and approximate solutions are obtained. By a numerical example, it is shown that for steel plates in water, with dimensions usually encountered in ship structures, the compressibility of water can be neglected.
A Theory of the Yield Point and the Transition Temperature of Mild Steel
Authors: Forscher F.
Published: June 2021

Experimental results indicate the dependence of the yield-point phenomenon of mild steel on temperature, strain rate, duration of stress, and stress state. This paper proposes a yield criterion which can account for these variables. The theory is developed on the basis of a “structural” model, by which the behavior of microscopic and submicroscopic elements is idealized. The theory postulates as yield criterion a critical number of relaxation centers (active Frank-Read sources) or, equivalently, a critical size of relaxation centers. The transition-temperature phenomenon is considered to be the result of an inhibition of yielding (upper yield point) by means of geometry, temperature and/or strain rate. A relation is given which expresses its dependence on the state of stress and strain rate.
A Method of Stepwise Integration in Problems of Impact Buckling
Authors: Schmitt A. F.
Published: June 2021

The equations for the dynamic buckling of an axially impacted column are discussed. A method is presented for the calculation of approximate load and deflection variations in problems of high-velocity impact. The method may be extended for cases wherein the stresses exceed the elastic limit. Results of calculations are presented for two cases. In one of these, agreement with a previous exact solution is found to be good.
Buckling of Rectangular Plates Uniformly Compressed in Two Perpendicular Directions With One Free Edge and Opposite Edge Elastically Restrained
Authors: Shuleshko P.
Published: June 2021

A short history of the buckling of elastic plates was considered by the author in previous papers (1, 2). The present paper deals with specific cases. Only those papers which directly concern this problem will be quoted.
Wave Propagation in an Elastic Rod Exhibiting Internal Coulomb Friction, Considered as a Model for a Ring Spring
Authors: Lee E. H. , Wang A. J.
Published: June 2021

The problem of stress-wave propagation in a ring spring is considered. A ring spring consists of rings placed normal to the spring axis with alternate internal and external conical bearing surfaces. The friction between these surfaces causes a loading-unloading relation which is strongly irreversible, leading to marked energy absorption for oscillatory stressing. The attenuation of a pulse of stress is analyzed in detail as it is propagated down a spring of infinite length. The influence of certain spring characteristics is evaluated. Concentration of the absorption of the total input energy is found in the region of the impact end of the spring, and particular examples are presented.
Studies on Plastic Flow of Anisotropic Metals
Authors: Hu L. W.
Published: June 2021

This investigation deals with a study of the plastic behavior of anisotropic metals. By extending Hill’s theory of plastic flow of anisotropic metals, plastic stress-strain relations for anisotropic materials with strain hardening are developed. Applications of these relations are also made to plane-stress and plane-strain problems with anisotropy. The effect of anisotropy on the stress distribution and on the pressure to produce yielding in a thick-walled cylinder under internal pressure is discussed. The influence of anisotropy on the interpretation of conventional biaxial tension-tension and tension-torsion tests is also considered in this study.
Rational Analysis of Heat-Exchanger Tube-Sheet Stresses
Authors: Yu Yi-Yuan
Published: June 2021

The paper presents a rational method of analysis of heat-exchanger tube-sheet stresses. While the tube sheet is taken to be a perforated plate on an elastic foundation in the manner of Gardner and Miller, it is also considered as part of an integrated indeterminate structure, and the interaction between the tube sheet and the connecting cylindrical shells and flange of the exchanger is determined so that a condition may be formulated which the edge rotation and edge moment of the tube sheet must satisfy. In general, neither the edge rotation nor the edge moment is zero; the edge of a tube sheet is therefore neither clamped nor simply supported. Application of the present method to four different types of heat exchangers is described in detail. To illustrate the method, Gardner’s example of a fixed-tube-sheet exchanger is recalculated. While Gardner’s method yields only the two limiting values of the maximum stress in the tube sheet, which differ by more than 100 per cent, the present method makes it possible to determine the exact value of this maximum stress. By means of the present method, the stresses in the other parts of the heat exchanger, namely, the tubes, shell, head, and flange, also can be calculated. As a consequence of the present analysis, it is found that, in the external-floating-head type of exchanger, the tube-sheet stress is not independent of the shell-side pressure, which is contrary to Gardner’s and Miller’s conclusions.
A Criterion for the Constancy of the Gage Factor of SR-4 Type Strain Gages
Authors: Kuczynski G. C.
Published: June 2021

It has been shown that the criterion of the gage-factor constancy of SR-4 type strain gages is that it is equal to 2 or nearly so. The experimental results agree with this theoretical conclusion.
The Mathematical Analysis of Bow Girders of Any Shape
Authors: Abbassi M. M.
Published: June 2021

By using parametric equations in which the parameter is the angle included between the tangent at any point on the bow girder and the tangent at the middle point, the analysis of bow girders of shapes other than the circular arc can be treated mathematically. Exact and approximate formulas are given for symmetrical bow girders of any shape carrying a distributed load or two equal concentrated loads placed symmetrically with respect to the middle point of the girder.
On the Stresses in a Strip Under Tension and Containing Two Equal Circular Holes Placed Longitudinally
Authors: Atsumi A.
Published: June 2021

A problem of determining the stresses in an infinite strip of finite breadth under tension and containing two equal circular holes placed on the longitudinal axis is studied theoretically. Stresses are calculated by a perturbation method, in each case the radius of the circle and the distance between the centers of two holes being varied. From consideration of the results obtained, some conclusions are made regarding the effects of the straight boundaries and the holes.
The Sector-Shaped Pad
Authors: Kettleborough C. F.
Published: June 2021

Boegli’s simplifying assumptions for the solution of the rectangular pad has been applied to the sector-shaped pad and extended to the case of varying viscosity. The process of obtaining the operating characteristics is very rapid and yields results comparable with those obtained by longer numerical methods.
On the Torsional Oscillations of a Solid Sphere in a Viscous Fluid
Authors: Carrier G. F. , Di Prima R. C.
Published: June 2021

Most treatments of the torsional oscillations of solid bodies assume that the velocity field is circumferential. In this paper the motion in planes containing the axis of oscillation is also considered. An expansion in terms of the angular displacement ϵ (assumed small) is made. The first approximation to the circumferential velocity is computed, and then used in computing the first approximation to the pumping motion. This is used to compute the correction to the circumferential velocity and, in particular, the correction to the viscous torque. For the range of parameters considered it is found that the correction to the torque is of the order of 0.04ϵ2|N0|, where N0 is the classical viscous torque. This problem is of interest in practical viscosity measurements.
Early Dynamics of a Laser-Induced Underwater Shock Wave
Authors: Lai Guihua , Geng Siyuan , Zheng Hanwen , Yao Zhifeng , Zhong Qiang , Wang Fujun
Published: June 2021

The objective of this paper is to observe and investigate the early evolution of the shock wave, induced by a nanosecond pulsed laser in still water. A numerical method is performed to calculate the propagation of the shock wave within 1 μs, after optical breakdown, based on the Gilmore model and the Kirkwood–Bethe hypothesis. The input parameters of the numerical method include the laser pulse duration, the size of the plasma, and the maximally extended cavitation bubble, which are measured utilizing a high time-resolved shadowgraph system. The calculation results are verified by shock wave observation experiments at the cavitation bubble expansion stage. The relative errors of the radiuses and the velocity of the shock wave front reach the maximum value of 45% at 5 ns after breakdown and decrease to less than 20% within 20 ns. The high attenuation characteristics of the shock wave after the optical breakdown are predicted by the numerical method. The quick time and space evolution of the shock wave are carefully analyzed. The normalized shock wave width is found to be independent of the laser energy and duration, and the energy partition ratio is around 2.0 using the nanosecond pulsed laser.
Effects of Lean Mode of Blade Trailing Edge on Pressure Fluctuation Characteristics of a Vertical Centrifugal Pump With Vaned Diffuser
Authors: Zeng Yongshun , Yao Zhifeng , Tao Ran , Liu Weichao , Xiao Ruofu
Published: June 2021

A vertical centrifugal pump with a vaned diffuser is very attractive in the field of long-distance water supply. Excessive pressure fluctuations in the vaneless region due to rotor–stator interaction (RSI) need careful evaluation. In the present investigation, the hydraulic performance and pressure fluctuation characteristics of a vertical centrifugal pump with three different lean modes of the blade trailing edge were quantitatively analyzed by comparison experiments, using the same test rig. Results showed that the pressure fluctuation level was the highest in the vaneless region, closest to the volute tongue, and increased as the flow rate deviated from the design flow rate. The lean mode of the blade trailing edge was found to have a slight influence on hydraulic performance, and the relative deviation of experimental specific speeds with three different lean modes was within 6%. The influence of the lean mode of the blade trailing edge on the pressure fluctuation level was experimentally verified for the first time. In particular, the flow rate-averaged peak-to-peak value of pressure fluctuation with the positive lean mode (PLM) was 62% of the corresponding value with the zero lean mode (ZLM), while no significant improvement was observed for the negative lean mode (NLM). The flow mechanism behind this may be explained as a weakening of the jet-wake flow pattern with PLM.
Fabrication of In Situ TiN Ceramic Particle Reinforced High Entropy Alloy Composite Coatings by Laser Cladding Processing
Authors: Wang X. H. , Liu S. S. , Zhao G. L. , Zhang M.
Published: June 2021

In situ TiN ceramic particle reinforced FeCoNiCrMnTi high entropy alloy coating was fabricated by laser cladding processing at high purity nitrogen gas atmosphere on the AISI 304 stainless steel substrate. The effect of Ti addition on the microstructure, phase structure, and wear properties of the coatings was investigated. The results showed that the phase structure of the coatings was mainly face-centered cubic (FCC)-type γ phase. A few of cubic or flower-like TiN ceramic were formed after adding titanium into the FeCoNiCrMn powder. When atomic ratio of Ti exceeds 0.5, Laves phases appeared in the coatings. With increasing of Ti, the micro-hardness and wear resistance of the coatings increased, but friction coefficient and crack resistance of the coatings reduced. Suitable Ti content in the FeCoNiCrMnTix, laser composite coating, had higher resistance to adhesive wear, oxidation wear, and cracking resistance.
Mechanical, Tribological, and Corrosion Properties of Composite NiP-Al2O3 With Different Amount of Particles
Authors: Pessoa Renato B. , Laurindo Carlos A. H. , Meruvia Michelle S. , Torres Ricardo D. , Mikowski Alexandre , Soares Marcos E. , Soares Paulo
Published: June 2021

In this study, the influence of Al2O3 particle amounts on the mechanical, tribological, and corrosion properties of the composite NiP-Al2O3 coating was evaluated. AISI 4140 steel was coated with NiP through an autocatalytic bath with the addition of Al2O3 particles maintained in suspension by mechanical stirring. Following, the coated samples were annealed at 600 °C to increase the hardness and to create an interdiffusion layer, which improves coating adhesion and corrosion resistance. The coating surface was characterized by scanning electron microscope (SEM)/energy-dispersive X-ray spectroscopy (EDS), X-ray diffraction (XRD), microhardness, wear resistance, and corrosion tests. The results showed that the coating particles’ amount depends on the bath agitation speed, the sample orientation during the deposition, and the volume of Al2O3 particles in the bath composition. Also, the number of particles in the coating affects the deposition kinetics and the thickness of the interdiffusion layer, which affects the wear and corrosion resistance.
Experimental Investigations on the Effect of Mixing Procedures on the Rheological Properties of Oilwell Cement Slurries
Authors: Saleh Fatemeh K. , Teodoriu Catalin
Published: June 2021

Well cementing is an essential operation in the oil and gas industry, and it is a key material to ensure wellbore integrity through the life of the well. Improper cement design can trigger well construction risks such as de-bonding and leakage pathways near-wellbore and through the annulus. Mixing non-Newtonian fluids is one of the most challenging tasks, especially for pseudoplastic fluids exhibiting yield stress, such as wellbore cement slurry. Mixing conditions for cement slurries and their effect on rheological properties and thickening time have been debated through the literature. In this study, based on laboratory-scale experiments, we provide testing results for rheological properties and thickening time by changing mixing conditions. Our results show that slurries mixed under similar mixing energy do not necessarily result in similar rheological properties. Comparing rheological measurements from lower mixing energy to higher mixing energy, plastic viscosity decreases; however, yield point increases. This implies the dual opposite effect of mixing time on rheological properties. This may have severe implications for field operations where mixing must be improved to enable successful cement operation.
Multilayer ultraviolet reflective coating based on atomic layer deposited aluminum oxide and fluoride
Authors: Huang Zhiyu , Messina Daniel C. , Eller Brianna S. , Koeck Franz A. , Scowen Paul A. , Nemanich Robert J.
Published: June 2021

Ultraviolet optical coatings employ wide bandgap dielectric materials due to their characteristic low absorption. High-reflectivity and antireflective coatings are essential for optical devices, which can be achieved by alternately depositing two dielectrics with different refractive indices. In this research, a multilayer high-reflectivity coating has been designed for middle UV wavelengths using Al2O3 and AlF3 layers on a sapphire (0001) substrate, and the initial two-layer structure has been fabricated by atomic layer deposition. The surface morphology and roughness of the coating was measured by atomic force microscopy after each deposition step. Ultraviolet spectroscopy and spectroscopic ellipsometry were used to characterize the optical performance of the single and multilayer coatings. Monochromatic x-ray photoemission spectroscopy was used to study the film composition, bonding, and impurities. A bilayer reflective coating was demonstrated, with a smooth surface (Rq < 1 nm) and peak reflectance of 25%−30% at a wavelength of 196 nm. The measured reflectance deviated from the simulations in the middle UV range, and an analysis of the AlF3 layer prepared by plasma enhanced atomic layer deposition indicated the presence of Al-rich clusters, which were associated with the UV absorption. A thermal atomic layer deposition process for AlF3 deposition showed reduced absorption, which could be more effective for shorter wavelength designs.
Classification of broadband target spectra in the mesopelagic using physics-informed machine learning
Authors: Cotter Emma , Bassett Christopher , Lavery Andone
Published: June 2021

Broadband echosounders measure the scattering response of an organism over a range of frequencies. When compared with acoustic scattering models, this response can provide insight into the type of organism measured. Here, we train the k-Nearest Neighbors algorithm using scattering models and use it to group target spectra (25–40 kHz) measured in the mesopelagic near the New England continental shelf break. Compared to an unsupervised approach, this creates groupings defined by their scattering physics and does not require significant tuning. The model classifies human-annotated target spectra as gas-bearing organisms (at, below, or above resonance) or fluid-like organisms with a weighted F1-score of 0.90. Class-specific F1-scores varied—the F1-score exceeded 0.89 for all gas-bearing organisms, while fluid-like organisms were classified with an F1-score of 0.73. Analysis of classified target spectra provides insight into the size and distribution of organisms in the mesopelagic and allows for the assessment of assumptions used to calculate organism abundance. Organisms with resonance peaks between 25 and 40 kHz account for 43% of detections, but a disproportionately high fraction of volume backscatter. Results suggest gas bearing organisms account for 98.9% of volume backscattering concurrently measured using a 38 kHz shipboard echosounder between 200 and 800 m depth.
Comparing acoustic analyses of speech data collected remotely
Authors: Zhang Cong , Jepson Kathleen , Lohfink Georg , Arvaniti Amalia
Published: June 2021

Face-to-face speech data collection has been next to impossible globally as a result of the COVID-19 restrictions. To address this problem, simultaneous recordings of three repetitions of the cardinal vowels were made using a Zoom H6 Handy Recorder with an external microphone (henceforth, H6) and compared with two alternatives accessible to potential participants at home: the Zoom meeting application (henceforth, Zoom) and two lossless mobile phone applications (Awesome Voice Recorder, and Recorder; henceforth, Phone). F0 was tracked accurately by all of the devices; however, for formant analysis (F1, F2, F3), Phone performed better than Zoom, i.e., more similarly to H6, although the data extraction method (VoiceSauce, Praat) also resulted in differences. In addition, Zoom recordings exhibited unexpected drops in intensity. The results suggest that lossless format phone recordings present a viable option for at least some phonetic studies.
Large historical carbon emissions from cultivated northern peatlands
Authors: Qiu Chunjing , Ciais Philippe , Zhu Dan , Guenet Bertrand , Peng Shushi , Petrescu Ana Maria Roxana , Lauerwald Ronny , Makowski David , Gallego-Sala Angela V. , Charman Dan J. , Brewer Simon C.
Published: June 2021

When a peatland is drained and cultivated, it behaves as a notable source of CO
2
. However, we lack temporally and spatially explicit estimates of carbon losses from cultivated peatlands. Using a process-based land surface model that explicitly includes representation of peatland processes, we estimate that northern peatlands converted to croplands emitted 72 Pg C over 850–2010, with 45% of this source having occurred before 1750. This source surpassed the carbon accumulation by high-latitude undisturbed peatlands (36 to 47 Pg C). Carbon losses from the cultivation of northern peatlands are omitted in previous land-use emission assessments. Adding this ignored historical land-use emission implies an 18% larger terrestrial carbon storage since 1750 to close the historical global carbon budget. We also show that carbon emission per unit area decrease with time since drainage, suggesting that time since drainage should be accounted for in inventories to refine land-use emissions from cultivated peatlands.
Tracking interfacial single-molecule pH and binding dynamics via vibrational spectroscopy
Authors: Huang Junyang , Grys David-Benjamin , Griffiths Jack , de Nijs Bart , Kamp Marlous , Lin Qianqi , Baumberg Jeremy J.
Published: June 2021

Trapping light to atomic scales enables yoctoliter spectroscopy, unveiling individual molecular deprotonation events.
Standalone real-time health monitoring patch based on a stretchable organic optoelectronic system
Authors: Lee Yeongjun , Chung Jong Won , Lee Gae Hwang , Kang Hyunbum , Kim Joo-Young , Bae Chisung , Yoo Hyunjun , Jeong Sujin , Cho Hyeon , Kang Sung-Gyu , Jung Ji Young , Lee Don-Wook , Gam Sangah , Hahm Suk Gyu , Kuzumoto Yasutaka , Kim Sang Joon , Bao Zhenan , Hong Yongtaek , Yun Youngjun , Kim Sunghan
Published: June 2021

A skin-like electronic health care patch is demonstrated with a stretchable organic light-emitting diode display and photodiode.
Intestinal cDC1 drive cross-tolerance to epithelial-derived antigen via induction of FoxP3
+
CD8
+
T
regs
Authors: Joeris Thorsten , Gomez-Casado Cristina , Holmkvist Petra , Tavernier Simon J. , Silva-Sanchez Aaron , Klotz Luisa , Randall Troy D. , Mowat Allan M. , Kotarsky Knut , Malissen Bernard , Agace William W.
Published: June 2021

Intestinal cDC1 drive the generation of FoxP3
+
CD8
+
T
regs
to maintain tolerance to epithelial-derived self-antigen.
Immunity to pathogenic free-living amoebae: role of cell-mediated immunity
Authors: Cursons R T , Brown T J , Keys E A , Moriarty K M , Till D
Published: June 2021

The role of cell-mediated immunity in defense against pathogenic free-living amoebae was examined. Both the in vitro macrophage inhibition test and the in vivo delayed hypersensitivity test showed responses to both heterologous and homologous antigens, although homologous systems were the most efficient. It is suggested that exposure to nonpathogenic species of free-living amoebae can stimulate the immune system to be effective against pathogenic species. The significance of cell-mediated immunity as a defense against invasion by pathogenic free-living amoebae is discussed.
Selective Antibacterial Properties of Lysozyme for Oral Microorganisms
Authors: Iacono Vincent J. , MacKay Bruce J. , DiRienzo Sharon , Pollock Jerry J.
Published: June 2021

The antibacterial properties of lysozyme were investigated with oral microorganisms representing the seven serotypes (
a
through
g
) of
Streptococcus mutans, Veillonella alcalescens
, and the virulent (V) and avirulent (AV) strains of
Actinomyces viscosus
T14. Growth of bacteria in defined medium was monitored spectrophotometrically after the addition of various amounts (25 μg to 5 mg/ml) of enzyme. No growth inhibition of
V. alcalescens
was observed. Inhibition of
A. viscosus
T14(V) and
A. viscosus
T14(AV) occurred with 160 μg of lysozyme per ml. Of the
S. mutans
cultures tested, the serotype
a
and
b
strains were inhibited with as little as 25 μg of enzyme per ml, whereas
e
and
f
strains were most resistant to the bacteriostatic activity of lysozyme. The presence of
dl
-threonine or sucrose in growth medium did not significantly affect the results. A lysoplate assay was developed to rapidly survey the bacterial cultures for their susceptibility to the lytic ability of the enzyme. Lysis, as a measure of a zone of clearing in agarose plates, occurred for all microorganisms in the presence of lysozyme after the subsequent addition of NaCl or detergent. The bactericidal activity of lysozyme was determined on
S. mutans
BHT and
S. mutans
LM-7 by the pour plate technique. Preincubation of
S. mutans
LM-7 with as much as 1 mg of enzyme for 90 min did not affect viability or growth, whereas preincubation of
S. mutans
BHT with 1 mg of lysozyme resulted in no recoverable colony-forming units. An antigen containing extract of
S. mutans
LM-7 blocked the growth inhibitory property of lysozyme. Human lysozyme was a more effective antibacterial factor than hen egg white lysozyme. Total growth inhibition of
S. mutans
BHT was effected with 40 μg of human enzyme, and as little as 10 μg of human enzyme inhibited growth for greater than 20 h. The data presented indicate that different mechanisms may be responsible for the bacteriostatic, lytic, and bactericidal properties of the enzyme and that lysozyme is a selective but effective antibacterial factor for oral microorganisms.
Heterotypic immunity to influenza in ferrets
Authors: Yetter R A , Barber W H , Small P A
Published: June 2021

Heterotypic immunity to influenza virus in ferrets operated against heterotypic influenza viruses but not heterologous viruses. Contrary to prior reports, the protection conferred lasted for at least 18 months. This type of immunity limited virus shedding but did not prevent infection. These results suggest that this phenomenon could play a role in determining the severity of infections caused by type A influenza viruses in humans.
Cutaneous Basophil Hypersensitivity and Contact Sensitivity After Cutaneous
Trichophyton mentagrophytes
Infection
Authors: Green Frederick , Anderson John W. , Balish Edward
Published: June 2021

The histopathology of cutaneous lesions and trichophytin skin test responses was examined by light microscopy after the infection of strain 2 guinea pigs with
Trichophyton mentagrophytes
. Skin biopsies were fixed and stained with procedures which allowed differentiation of the polymorphonuclear granulocytic leukocytes that were present in lesions or skin test reactions. Basophils comprised about one-third of the leukocytes infiltrating the 24 to 48-h trichophytin skin test reactions of guinea pigs sensitized by a cutaneous
T. mentagrophytes
infection. These results were comparable to the percentage of basophils counted in skin test lesions elicited by the contact agent dinitrochlorobenzene and are consistent with previously published descriptions of cutaneous basophil hypersensitivity. In contrast, the active
T. mentagrophytes
lesion in the skin of guinea pigs sacrificed at defined intervals after infection or reinfection did not appear to contain similarly elevated numbers of basophils. The early inflammation in primary
T. mentagrophytes
-induced skin lesions can be characterized histologically as a primary irritant dermatitis which evolves, during the course of the disease, into a chronic mononuclear inflammation. This shift apparently results from host sensitization to fungal antigens during infection and the concurrent development of acquired immunity. Reinfection of guinea pigs with
T. mentagrophytes
resulted in an accelerated cutaneous inflammation that was temporally and histologically similar to allergic contact dermatitis. These results support the hypothesis that contact sensitivity to
T. mentagrophytes
develops during the primary cutaneous infection of guinea pigs and is an early component of the hypersensitivity response to reinfection.
Virulence-Related Physiological Changes and Antigenic Variation in Populations of
Streptococcus mutans
Colonizing Gnotobiotic Rats
Authors: Gibbons R. J. , Qureshi J. V.
Published: June 2021

The purpose of this study was to determine if populations of
Streptococcus mutans
which were undergoing antigenic variation while colonizing gnotobiotic rats concomitantly became altered in physiological characteristics which affected their virulence.
S. mutans
strain JBP (serotype c), which was freshly isolated from a carious lesion in a 6-year old child, was used to inoculate gnotobiotic rats; uninfected animals served as controls. Substrains were isolated from animals 1, 2, 3, 4, and 12 weeks after infection; samples of pilocarpine-stimulated saliva were also obtained from representative animals for antibody analyses. Isolates derived from stock cultures of strain JBP proved to be homogeneous with respect to all of the physiological characteristics monitored. However, substrains isolated from the animals within 4 weeks after infection were altered with respect to their ability to agglutinate in the presence of sucrose, their ability to form adherent growth in sucrose broth, and the terminal pH attained in glucose broth. Some isolates obtained 12 weeks after infection no longer synthesized detectable levels of c antigen or intracellular glycogen, and they formed atypical smooth colonies on mitis salivarius agar. With an enzyme-linked immunosorbent assay, low levels of immunoglobulin A (IgA) antibodies reactive with whole JBP cells were detected in saliva samples of uninfected control animals at each sampling period; these evidently were induced to antigens contained in the diet of the animals. Significantly higher levels of IgA antibodies were present in saliva samples from animals infected with strain JBP for 3 weeks or longer. Thus, the emergence of antigenic and physiological variants of
S. mutans
in the animals was paralleled by increased levels of salivary IgA antibodies. The reactivity of salivary IgG with JBP cells was low, and it fluctuated in both groups of animals. No antibodies of the IgM class were detected. When tested in gnotobiotic rats, several variants, including strains which no longer formed typical rough colonies or adherent growth in sucrose broth, proved much less virulent than parental strain JBP in inducing carious lesions. Prior oral immunization, which resulted in higher levels of salivary and serum IgA antibodies reactive with strain JBP, was found to accelerate the emergence of smooth-colony variants in the animals; it was also associated with decreased streptococcal population levels on the teeth and in feces of the rats. It is suggested that part of the mechanism by which artificial immunization leads to a reduction in dental caries development in experimental animals is due to the earlier selection of less virulent streptococcal populations.
Persistence of Human Adenovirus 5 in Human Cord Blood Lymphoblastoid Cell Lines Transformed by Epstein-Barr Virus
Authors: Faucon N. , Desgranges C.
Published: June 2021

Lymphoblastoid cell lines derived from human cord blood leukocytes were persistently infected with human adenovirus 5. These cell lines expressed the Epstein-Barr nuclear antigen, but no other Epstein-Barr virus-related antigen. They continually produced infectious adenovirus 5 particles, but this production could be inhibited by the presence of specific neutralizing antibody to adenovirus 5. This suggests that the persistent infection might be due to the continual reinfection of susceptible cells by complete virus.
Bactericidal effect of hydrogen peroxide is prevented by the lactoperoxidase-thiocyanate system under anaerobic conditions
Authors: Carlsson J
Published: June 2021

Streptococcus sanguis and Peptostreptococcus anaerobius were exposed to various combinations of the components of the lactoperoxidase-thiocyanate-hydrogen peroxide system. The bactericidal effect of hydrogen peroxide was prevented under anaerobic conditions by lactoperoxidase together with thiocyanate, but not by lactoperoxidase or thiocyanate alone. Thiocyanate was effective already at a molar ratio to hydrogen peroxide of 1:100.
Adjuvant Activity of
N
-Acetyl Muramyl Dipeptides for the Induction of Delayed-Type Hypersensitivity to Azobenzenearsonate-
N
-Acetyl-
l
-Tyrosine in Guinea Pigs
Authors: Azuma Ichiro , Kamisango Kei-Ichi , Saiki Ikuo , Tanio Yoshiro , Kobayashi Shigeru , Yamamura Yuichi
Published: June 2021

The adjuvant activity of 23 kinds of synthetic
N
-acetyl muramyl dipeptide analogs on the induction of delayed-type hypersensitivity to azobenzenearsonate-
N
-acetyl-
l
-tyrosine was examined in guinea pigs.
Uneven distribution of antitreponema antibody acitivity in differing immunoglobulin G fractions from patients with early syphilis
Authors: van der Sluis J J , Boer M
Published: June 2021

Three fractions, containing immunoglobulin G's (IgG's) of differing relative electrophoretic mobility, were isolated from sera of 33 male patients with untreated early syphilis. Serological testing, employing four different serodiagnostic procedures for these fractions at equal amounts of IgG, revealed a very constant reaction pattern for all patients. In the earliest stages of the disease, the most basic fraction was the first to show antibody activity. In progressive stages, antibody activity subsequently was also found in the two less basic fractions. However, in all stages of disease studied, the basic part of the IgG made the largest contribution of the total antibody activity within the IgG class, indicating an uneven distribution of antitreponema antibody activity over heterogeneous IgG. Several possible explanations of the observations are discussed.
Interaction of streptolysin O from Streptococcus pyogenes and theta-toxin from Clostridium perfringens with human fibroblasts
Authors: Thelestam M , Möllby R
Published: June 2021

The membrane-damaging properties on human diploid embryonic lung fibroblasts of streptolysin O (from Streptococcus pyogenes) and theta-toxin (from Clostridium perfringens) were compared. The results are consistent with the suggested mechanism for hemolysis by streptolysin O involving one fixation site and one lytic site of this cytolysin. However, the membrane-damaging activity of the two toxins differed with respect to (i) relative cytolytic activity on human diploid lung fibroblasts compared with that on sheep erythrocytes, (ii) binding to the fibroblast membrane, (iii) activity at 0 degrees C, (iv) membrane repair after more than 30 min, and (v) effect on influx of amino acids. It is concluded that the mechanism of membrane damage caused by theta-toxin differs from that of cytoplasmic membrane. These results question the current concept that all thiol-activated, cholesterol-inactivated bacterial toxins are similar both structurally and functionally.
Genome-Wide Variation in Betacoronaviruses
Authors: LaTourrette Katherine , Holste Natalie M. , Rodriguez-Peña Rosalba , Leme Raquel Arruda , Garcia-Ruiz Hernan
Published: June 2021

Natural infection with SARS-CoV-2 and vaccines triggers the formation of antibodies against the S glycoprotein, which are detected by antibody-based diagnostic tests. Our analysis showed that variation in the S glycoprotein is a general feature of all species in the genus
Betacoronavirus
, including three species that infect humans: SARS-CoV, SARS-CoV-2, and MERS-CoV.
Structure of the transcriptionally repressed phosphate-repressible acid phosphatase gene (PHO5) of Saccharomyces cerevisiae
Authors: Bergman L W , Stranathan M C , Preis L H
Published: June 2021

We developed a high-copy-number plasmid system containing the entire structural and regulatory sequences of the phosphate-repressible acid phosphatase (PHO5) gene and the TRP1/ARS1 replicator sequences of the yeast Saccharomyces cerevisiae to investigate the mechanism of repression-derepression of transcription. The resulting plasmid was used to transform either wild-type cells or a number of strains which contain mutations in various trans-acting regulatory loci for the production of acid phosphatase. Results of analysis of mRNA levels isolated from the transformed strains grown under repressed or derepressed conditions suggested that normal transcriptional regulation of the gene persisted, although gene copy number was significantly increased. Analysis of changes in linking number (i.e., the number of negative supercoils) of the plasmid isolated under repressed and derepressed growth conditions revealed that the transcriptionally inactive plasmid contained approximately three more negative supercoils than the transcriptionally active plasmid. This difference in topological state was similarly seen in a plasmid containing a sequence-related acid phosphatase gene (PHO11) under the same regulatory control system, but it was not seen in plasmids isolated from some strains containing mutations which caused either fully constitutive or nonderepressible production of acid phosphatase. Finally, analysis of the nucleosome positioning along the inactive gene sequence revealed that an abnormally broad internucleosomal spacer is present in a region presumed to function in the regulation of transcription by the level of Pi in the growth media.
Idiopathic acute transverse myelitis in a middle-aged woman with progression to nadir in less than one hour
Authors: Aloba Jamiu Omotayo , Muradia Sagarika , Monaghan Alexandra , Afolabi Zainab , Prasad Rama Shankar
Published: June 2021

We report a case of a middle-aged woman, normally fit and well, presenting with acute onset neurological deficit with progression to nadir in <1 hour. Initial MRI spine showed no significant abnormality, although second MRI spine showed abnormal signal in three to four segments with no compressive lesion. CT aortic angiography excluded vascular or ischaemic abnormality. We made a diagnosis of idiopathic acute transverse myelitis (ATM). She was treated with steroids and made significant progress improving from T11 ASIA A paraplegia to T11 ASIA C paraplegia by the time of discharge. Awareness of idiopathic ATM presenting hyperacutely with initial MRI spine being normal is important for prompt diagnosis and management.
Bilateral fingolimod-associated macular oedema development after cataract surgery
Authors: Gillam Matthew , Richardson Theresa
Published: June 2021

Postoperative cystoid macular oedema (CMO) is a recognised complication of cataract surgery, occurring in around 1.5% of cases. It is generally managed with topical steroids or non-steroidal anti-inflammatory medications. We present a case of a patient who developed bilateral sequential CMO following bilateral sequential cataract surgery which was non-responsive to topical therapy and worsened following sub-Tenons administration of steroid. The patient took fingolimod for multiple sclerosis both prior to and during the period of cataract surgery which is known to result in the development of macular oedema in some patients. On fingolimod cessation, the oedema resolved over a period of 5 months with good visual recovery. We present this case to inform cataract surgeons of the risk of fingolimod-associated macular oedema in patients undergoing cataract surgery and to inform neurologists of the potential need to adjust treatment for patients undergoing cataract surgery.
Challenge of food allergy testing and avoidance in children with atopic dermatitis
Authors: Kubala Stephanie Ann , Mohyi Paula Mariam , Sokol Kristin , Frischmeyer-Guerrerio Pamela
Published: June 2021

Atopic dermatitis (AD) is a common presenting complaint by children and their caretakers to their primary care providers. On testing, children with AD frequently exhibit positive food-specific IgE levels in the absence of immediate allergic reactions. Misinterpretation of these false positive tests can lead to unnecessary food avoidance, which can have tremendous psychosocial, economic and nutritional consequences and, in some cases, facilitate the development of an immediate hypersensitivity to the food. We present a child with persistent AD who underwent broad testing that led to unnecessary food avoidance resulting in Vitamin D deficiency, growth failure and the development of an IgE-mediated food allergy. This case underscores the need for caution by primary care clinicians in using food avoidance diets as a treatment for AD and the importance of limiting allergy testing to foods only when the clinical history indicates an immediate hypersensitivity reaction.