bluuebunny/crossref_metadata_2025 huggingface dataset:
Quantum coins, dice, and children: Probability and quantum statistics
Authors: Chow Chi-Keung , Cohen Thomas D.
Published: July 2002

We discuss counterintuitive aspects of probabilities for systems of identical particles obeying quantum statistics. Quantum coins and children (two level systems) and quantum dice (many level systems) are used as examples. It is emphasized that, even in the absence of interactions, (anti)symmetrizations of multiparticle wave functions destroy statistical independences and often lead to dramatic departures from our intuitive expectations.
On the circular hydraulic jump
Authors: Brechet Y. , Néda Z.
Published: July 2002

We study both experimentally and theoretically the classical problem of the circular hydraulic jump. By means of elementary hydrodynamics we investigate the scaling laws governing the position of the hydraulic jump and compare our predictions with experimental data. The results of our simple model are in good agreement with the experiments and with more elaborate approaches. The problem can be effectively used for educational purposes, being appropriate both for experimental investigations and for theoretical application of many fluid mechanics concepts.
An improved version of the Haynes–Shockley experiment with electrical or optical injection of the excess carriers
Authors: Sconza A. , Galet G. , Torzo G.
Published: July 2002

The Haynes–Shockley experiment allows direct measurements of the drift mobility, of the diffusion coefficient, and of the recombination lifetime of excess carriers in semiconductors. In order to obtain easier and more accurate measurements in a didactic laboratory, we designed a new setup for this experiment that uses electrical or optical injection of the excess carriers.
Application of a multiple-beam model for lateral vibration analysis of a discretely supported rail at high frequencies
Authors: Wu T. X. , Thompson D. J.
Published: July 2002

In this paper a multiple-beam model of the rail, which allows all the essential deformations caused by the lateral vibration, has been applied for studying the lateral vibration behavior related to the discrete supports. Detailed investigation of the lateral vibration of a discretely supported rail has been carried out using a Green's function matrix and the superposition principle. Good agreement between the predictions and measurement data has been reached in terms of accelerance.
Auditory discrimination in a sound-producing electric fish (Pollimyrus): Tone frequency and click-rate difference detection
Authors: Marvit Peter , Crawford John D.
Published: July 2002

Pollimyrus adspersus is a fish that uses simple sounds for communication and has auditory specializations for sound-pressure detection. The sounds are species-specific, and the sounds of individuals are sufficiently stereotyped that they could mediate individual recognition. Behavioral measurements are presented indicating that Pollimyrus probably can make species and individual discriminations on the basis of acoustic cues. Interclick interval (ICI; 10–40 ms) and frequency (100–1400 Hz) discrimination was assessed using modulations of the fish’s electric organ discharge rate in the presence of a target stimulus presented in alternation with an ongoing base stimulus. Tone frequency discrimination was best in the 200–600-Hz range, with the best threshold of 1.7% ±0.4% standard error at 500 Hz (or 8.5 Hz ±1.9 SE). The just noticeable differences (jnd’s) were relatively constant from 100 to 500 Hz (mean 8.7 Hz), then increased at a rate of 13.3 Hz per 100 Hz. For click trains, jnd’s increased linearly with ICI. The mean jnd’s for 10- and 15-ms ICI were both 300 μs (SE=0.8 ms at 10-ms ICI, SE=0.11 ms at 15-ms ICI). The jnd at 20-ms ICI was only 1.1 ms ±0.25 SE.
Robustness to head misalignment of virtual sound imaging systems
Authors: Takeuchi Takashi , Nelson Philip A. , Hamada Hareo
Published: July 2002

When binaural sound signals are presented with two loudspeakers, the listener’s ears are required to be in the relatively small region which is under control of the system. Misalignment of the head results in inaccurate synthesis of the binaural signals. Consequently, directional information associated with the acoustic signals is inaccurately reproduced. When the two loudspeakers are placed close together, the spatial rate of change of the generated sound field is much smaller than that generated by two loudspeakers spaced apart. Therefore, the performance of such a system is expected to be more robust to misalignment of the listener’s head. Robustness of performance is investigated here with respect to head displacement in three translational and three rotational directions. A comparison is given between systems consisting of two loudspeakers either placed close together or spaced apart. The extent of effective control with head displacement and the resulting deterioration in directional information is investigated in the temporal and spectral domain by analyzing synthesized binaural signals. Subjective localization experiments are performed for cases in which notable differences in performance are expected from the previous analysis. It is shown that the system comprising two loudspeakers that are close together is very robust to misalignment of the listener’s head.
Matched-field source tracking by ambiguity surface averaging
Authors: Fialkowski Laurie T. , Perkins John S. , Collins Michael D. , Nicholas Michael , Fawcett John A. , Kuperman W. A.
Published: July 2002

The method of matched-field source tracking by ambiguity surface averaging is demonstrated using low-frequency shallow-water acoustic data recorded on a vertical array. In this method, source motion is taken into account by averaging values from individual, short time-average matched-field ambiguity functions; each resulting average value corresponds to a trial source track. The result is a new ambiguity function which depends on six parameters: the three-dimensional coordinates of the initial and final source positions. A simplification to four parameters is made by assuming the source remains at a constant depth. Only mild restrictions are made on trial tracks considered, and the resulting ambiguity surfaces can be plotted as a function of final coordinates by holding the initial coordinates fixed at the optimal position. When applied to experimental data, the number of high sidelobes present in individual matched-field ambiguity surfaces is greatly reduced. Also, the technique appears robust to uncertainties in replica computation (due to various mismatch problems) and periods when the signal-to-noise ratio is low.
An introduction to statistical energy analysis
Authors: Burroughs Courtney B. , Fischer Raymond W. , Kern Fred R.
Published: July 2002

The basic concepts and underlying assumptions of Statistical Energy Analysis (SEA) are reviewed. Using coupled simple oscillators as models for resonant modes, power balance equations are derived. Equipartition of energy among modes within a subsystem, and strong versus weak coupling between subsystems are discussed. Input requirements for exercising SEA power balance equations are defined and methods of obtaining the required input are outlined. Examples of the applications of SEA are presented and discussed.
Acousto-ultrasonic technique for nondestructive evaluation of composites and structures
Authors: Raju P. K.
Published: July 2002

Acousto-ultrasonics (AU) is a nondestructive testing technique for evaluating materials and structures. The name is based on the fact that principles of acoustic emission and ultrasonics are combined in this technique. Unlike conventional ultrasonics, acousto-ultrasonics is not concerned with the detection and characterization of individual flaws. Instead, it is concerned with evaluation of integrated effects of diffuse subcritical flaw populations and microstructural aberrations in composites. Porosity, fiber breaks, resin richness, poor curing, and fiber/matrix bonding are some examples of these, which in turn govern mechanical properties and durability of composite structures. These factors also influence AU signals that consequently reveal that variations in mechanical properties such as tensile strength, stiffness, toughness, etc. [A. Vary, ‘‘Acousto-Ultrasonics,’’ NDT of Fiber Reinforced Plastics Composites, Vol. 2 (Elsevier Applied Science, 1990)]. This paper reviews the current state of the art of this technique. Some examples on the use of AU for characterization of composites and evaluation of the adhesive bond strength of composite structures will be discussed. Finally, some of the advantages and limitations of this technique will also be discussed.
Sound perception of the urban environment through an audio-visual approach
Authors: Viollon Stephanie , Lavandier Catherine , Drake Carolyn
Published: July 2002

Sound and visual environments of cities are usually studied separately without taking into consideration possible interactions between the two sensory modalities. The present research aims at developing an audio-visual approach for assessing the sound perception of the urban environment. It means an innovative approach which takes into account the influence of visual information on the sound judgment. In a preliminary in situ questionnaire, participants rated real-life urban environments along pairs of descriptive adjectives all related to the auditory modality. A Principle Components Factor Analysis revealed four perceptive factors characterizing the perception of the urban environment and also revealed two auditory variables which were the most influenced by the visual setting. Then, with a simulation experimental setting involving the creation of audio and visual artificial fields, a series of semantic differential tests was carried out. Listeners were required to rate the two auditory variables: appeasing–stressing and pleasant–unpleasant for eight sound urban environments and for four different visual settings. The results point out that judgments about the two sound variables are significantly influenced by the visual setting. Moreover, improvements in the experimental procedure suitable for testing audio–visual interactions in an urban context are discussed.
Improved Green’s function parabolic equation method for atmospheric sound propagation
Authors: Salomons Erik M.
Published: July 2002

The numerical implementation of the Green’s function parabolic equation (GFPE) method for atmospheric sound propagation is discussed. Four types of numerical errors are distinguished: (i) errors in the forward Fourier transform; (ii) errors in the inverse Fourier transform; (iii) errors in the refraction factor; and (iv) errors caused by the split-step approximation. The sizes of the errors depend on the choice of the numerical parameters, in particular the range step and the vertical grid spacing. It is shown that this dependence is related to the stationary phase point of the inverse Fourier integral. The errors of type (i) can be reduced by increasing the range step and/or decreasing the vertical grid spacing, but can be reduced much more efficiently by using an improved approximation for the forward Fourier integral. The errors of type (ii) can be reduced by using a numerical filter in the inverse Fourier integral. The errors of type (iii) can be reduced slightly by using an improved refraction factor. The errors of type (iv) can be reduced only by reducing the range step. The reduction of the four types of errors is illustrated for realistic test cases, by comparison with analytic solutions and results of the Crank–Nicholson PE (CNPE) method. Further, optimized values are presented for the parameters that determine the computational speed of the GFPE method. The computational speed difference between GFPE and CNPE is discussed in terms of numbers of floating point operations required by both methods.
Local sound field reproduction using two closely spaced loudspeakers
Authors: Kirkeby Ole , Nelson Philip A. , Hamada Hareo
Published: July 2002

When only two loudspeakers are used for the reproduction of sound for a single listener, time domain simulations show that it is advantageous that the two loudspeakers are very close together. The sound field reproduced by two loudspeakers that span 10 degrees as seen by the listener is simpler, and locally more similar to the sound field generated by a real sound source, than that reproduced by two loudspeakers that span 60 degrees. The basic physics of the problem is first explained by assuming that the sound propagates under free-field conditions. It is then demonstrated that when the influence of the listener on the incident sound waves is taken into account by modeling the listener’s head as a rigid sphere, the results are qualitatively the same as in the free-field case. Consequently, two closely spaced loudspeakers are capable of accurately reproducing a desired sound field, not only at the ears of the listener but also in the vicinity of the listener’s head. This result, although counter-intuitive, is very encouraging. In particular, it suggests that many low-fidelity audio systems, such as those currently supplied with most multi-media computers, can be greatly improved.
Underwater acoustic tank evaluation of acoustic properties of samples using spectrally dense signals
Authors: Ranz-Guerra Carlos , Cobo-Parra Pedro
Published: July 2002

This paper deals with exploring the availability and reliability of subtraction techniques, based on spectrally dense signals such as maximum length sequences, in evaluating the echo reduction losses and transmitting properties of samples of interest in underwater acoustics. These techniques, first employed in air acoustics, were adapted to the underwater environment. Experimental results show how a measurement can be accomplished and the limitations produced by the actual available combination of soft, hardware and tank and samples dimensions. [The authors wish to acknowledge the help given by the CICYT, Project AMB97-1175-C03-01, for allowing them to use the software, hardware, and related facilities in carrying out the work described by this paper.]
Experimental verification of a radial mode analysis technique using wall-flush mounted sensors
Authors: Enghardt Lars , Zhang Yanchang , Neise Wolfgang
Published: July 2002

Sound fields in the inlet and outlet ducts of axial fans, compressors, and aircraft engines propagate as higher-order acoustical modes in a wide-frequency range. Decomposition of the sound field into azimuthal and radial modes permits direct conclusions on the sound generation processes and can lead to the identification of aerodynamic source areas. An established experimental method for assessing the sound field is to circumferentially traverse a radial microphone rake over 360 degrees, to measure the sound pressure in the duct at multiple circumferential and radial positions. On the inlet side of a turbo-machine this procedure cannot be employed because the wake of the rake would disturb the inlet flow conditions of the machine and alter its acoustic characteristics. Computer simulations have shown that the radial mode structure of the sound field can also be determined by measuring the sound pressure only at the inner duct wall, but at different axial locations. In this paper, experiments are described where the sound field in the outlet duct of an axial-flow fan is measured once with the conventional radial microphone rake and a second time with wall-flush mounted microphones. Subsequent radial mode analyses are carried out for both sets of measurement data to experimentally verify the new method.
Polymer Melt Flow Instabilities in Extrusion: Investigation of the Mechanism and Material and Geometric Variables
Authors: Ballenger Timothy F. , Chen I-Jen , Crowder Jerry W. , Hagler Gerald E. , Bogue Donald C. , White James L.
Published: July 2002

A comprehensive study of the effect of material, geometric, and operating variables on the onset of melt flow instabilities in extrusion was made. Primary objectives were to compare such melt instabilities for a variety of materials and to correlate instability criteria with independent rheological parameters. Seven polymer melts were studied: two polyethylenes, polypropylene, polystyrene, two polybutadienes, and an SBR copolymer. Two distinct extrusion apparatuses were used: a die fed by a screw extruder system and a die fed by an Instron rheometer. The variables studied were temperature, entry cone angle, length/diameter ratio of the die, and flow rate. Independent rheological measurements were performed. These consisted of the evaluation of normal stresses on the Weissenberg rheogoniometer, entrance pressure drop measurements on the Instron rheometer, and viscosity measurements on both instruments and the screw extruder. In a companion study, flow visualization studies were made in the die entry region of the Instron rheometer, for most of the above materials and also a solution of polyisobutylene and glycerine. Distinctively different patterns were observed for the various materials, ranging from severe channeling with corner eddies to nonchanneling flow. Interrelationships between the onset of instabilities with other measurements were noted. In comparing a variety of materials, a decrease in the critical shear rate is generally associated with an increased tendency of the material to channel, an increased normal stress/shear stress ratio and an increased entrance pressure drop/shear stress ratio. It is argued that the instability phenomena are strongly associated with the elastic properties of the materials.
Mechanisms for viscosity reduction of polymer blends: Blends of fluoroelastomer and high-density polyethylene
Authors: Chan Chi-Ming , Feng Jiyun
Published: July 2002

The rheological behavior of fluoroelastomer high-density polyethylene (HDPE) blends was investigated in detail. A capillary rheometer was used to determine the apparent viscosity of the blends as a function of time at various shear rates. The time to attain the steady state and the normalized steady-state apparent viscosity of the blends depend on shear rate and the fluoroelastomer concentration. The reduction in the apparent viscosity is caused by adhesive failure at the interface between the HDPE melt and the fluoroelastomer layer which was formed on the die wall surface during the extrusion of the blends. The presence of the fluoroelastomer layer on the die wall surface was confirmed by x-ray photoelectron spectroscopy and rheological measurements. Based on our previous work and this work, we have discovered that there are at least two different mechanisms—adhesive failure at the interface between the extrudate and the lubricating layer or cohesive failure in the lubricant layer—for viscosity reduction in polymer blends.
Heparin promotes rapid fibrillation of the basic parathyroid hormone at physiological pH
Authors: Lauth Luca M. , Voigt Bruno , Bhatia Twinkle , Machner Lisa , Balbach Jochen , Ott Maria
Published: July 2022

In acidic secretory granules of mammalian cells, peptide hormones including the parathyroid hormone are presumably stored in the form of functional amyloid fibrils. Mature PTH, however, is considerably positively charged in acidic environments, a condition known to impede unassisted self‐aggregation into fibrils. Here, we studied the role of the polyanion heparin on promoting fibril formation of PTH. Employing ITC, CD spectroscopy, NMR, SAXS, and fluorescence‐based assays, we could demonstrate that heparin binds PTH with submicromolar affinity and facilitates its conversion into fibrillar seeds, enabling rapid formation of amyloid fibrils under acidic conditions. In the absence of heparin, PTH remained in a soluble monomeric state. We suspect that heparin‐like surfaces are required in vivo to convert PTH efficiently into fibrillar deposits.
Frequency and Clinical Utility of Antibodies to Extractable Nuclear Antigen in the Setting of a Negative Antinuclear Antibody Test
Authors: Yeo Ai Li , Ojaimi Samar , Le Suong , Leech Michelle , Morand Eric
Published: July 2022

Objective

Simultaneous antibody testing during screening for autoimmune conditions is discouraged. The incidence of positive extractable nuclear antigen (ENA) in the setting of a negative antinuclear antibody (ANA) has been reported as low. Our objective was to characterize the frequency of diagnosis of new ANA‐associated rheumatic disease (AARD) in the setting of a negative ANA with a positive ENA.

Methods

This was a 7‐year retrospective study from a multicenter tertiary health network in Australia. Clinical information was sought on patients over 18 years old who had a negative ANA but positive ENA test result. Results were extracted from hospital computer systems.

Results

From March 19, 2011, to July 23, 2018, ENA testing was ordered simultaneously with an ANA test on 4,248 occasions in 3,484 patients. ANA was positive in 2,520 patients (59.3%) and ENA was positive in 1,980 patients (46.6%). Among positive ANA patients, ENA was positive in 1,563 patients (62.0%). Among 1,728 negative ANA tests, ENA was positive in 417 (24.1%) (P < 0.001). A total of 328 patients with discordant ANA/ENA results had data available for further analysis, of whom 279 had no pre‐established rheumatologic condition. A new AARD was diagnosed in 17 of 279 patients, yielding a positive predictive value of 6.09% (95% confidence interval 3.59–9.58).

Conclusion

Despite the higher‐than‐expected incidence of positive ENA in the setting of a negative ANA, the yield of newly diagnosed rheumatic diseases was low. Our findings support the stepwise addition of ENA requests when an ANA test result is positive and clinical suspicion of an AARD is high.
Business opportunity: Adding mental illness care to SUD treatment
Authors: Knopf Alison
Published: July 2022

The lack of adequate treatment for mental illness has been highlighted by the COVID‐19 pandemic, but addiction treatment providers have always recognized that the needs of patients go beyond merely treating the substance use disorder (SUD), and certainly go beyond achieving abstinence. A decade or so ago, the concept of trauma as a precipitating cause of SUDs emerged, with the realization that unless that trauma was treated, the addiction treatment wouldn't hold. Even before then, there were important concepts of self‐medication, in which patients who did not understand why they were addicted eventually learned—if they were fortunate enough to have helpful providers—that their problems were not just about using alcohol or drugs.
ONDCP: Improving drug crisis response requires data on nonfatal overdoses
Authors: Enos Gary
Published: July 2022

As the number of annual overdose deaths in the U.S. have soared past the 100,000 mark, the gap between the scale of the crisis and the scope of the data systems that are designed to track it has similarly grown. Leaders in the Office of National Drug Control Policy (ONDCP) at the White House have called for the establishment of a national reporting system that encompasses nonfatal overdoses, in a process that they acknowledge will take at least two to three federal budget cycles to execute.
Laser Beam Welding of CoCuFeMnNi High Entropy Alloy: Processing, Microstructure, and Mechanical Properties
Authors: Fiocchi Jacopo , Casati Riccardo , Tuissi Ausonio , Biffi Carlo Alberto
Published: July 2022

The present work explores the feasibility of joining the CoCuFeMnNi high entropy alloy by laser beam welding. An appropriate feasibility window is identified, and the optimal process parameters (300 W power, scanning speed 20 mm s−1, spot size 0.45 mm) are related to the properties of the studied material. Cu's tendency to segregate from other alloying elements is found to dominate the microstructural evolution: the welding process induced the formation of Cu‐rich second phases within the melted zone (MZ), as interdendritic phase, as well as in the heat‐affected zone (HAZ) as grain boundary phase. Mechanical resistance of the welded beads and the HAZs was improved (187 HV on average) over one of the base materials (BMs) (160 HV on average) owing to the formation of Cu‐rich phases and solidification stresses. Consequently, tensile strength (576.4 MPa) and elongation to failure (28.3%) are almost the same as in the BM. Indeed, failure during tensile tests always took place outside the welded bead, therefore confirming the extreme soundness of the performed laser beam welding. Such results confirm that laser welding may be safely applied to relatively complex high entropy alloys (HEA), thus easing their practical application.
Novel Additive Manufacturing Materials for Waste Heat Deduction
Authors: Schuschnigg Stephan , Hufnagl Margarete , Holzer Clemens , Eder Florian , Kroke Edwin , Schallmeiner Stefan , Regula Christoph , Hamedi Yaser , Gorsche Christian , Morganti Elena , Seidler Konstanze
Published: July 2022

Herein, three material approaches, for the fabrication of thermally conductive and yet electrically insulating parts via additive manufacturing (AM) technologies, are described. Samples are prepared from light‐curable resins, sol–gel‐hybrid polymers, and thermoplastic materials using thermally conductive particles as fillers. AM sample preparation is done using vat photo‐polymerization and material extrusion with subsequent measurements of thermal conductivity and electrical insulation properties. The main goal herein in addition to material development is the demonstration of manufacturing applicability including usage properties. Use cases are heat sinks for power electronics, which have to be thermally conductive to spread the generated heat and electrically insulating to ensure general functionality and long‐term operation.
Ultrathin Suspended Chiral Metasurfaces for Enantiodiscrimination
Authors: Cen Mengjia , Wang Jiawei , Liu Jianxun , He Huilin , Li Ke , Cai Wenfeng , Cao Tun , Liu Yan Jun
Published: July 2022

Chiral metasurfaces can exhibit a strong circular dichroism, but it is limited by the complicated fabrication procedure and alignment errors. Here, a new type of self‐aligned suspended chiral bilayer metasurface with only one‐step electron beam lithography exposure is demonstrated. A significant optical chirality of 221° µm−1 can be realized using suspended metasurfaces with a thickness of 100 nm. Furthermore, this study experimentally demonstrates that such a structure is capable of label‐free discrimination of the chiral molecules at zeptomole level, exhibiting a much higher sensitivity (orders of magnitude) compared to the conventional circular dichroism spectroscopy. The fundamental principles for chiral sensing using molecules–metasurfaces interactions are explored. Benefiting from the giant chiroptical response, the proposed metadevice may offer promising applications for ultrathin circular polarizers, chiral molecular detectors, and asymmetry information processing.
Efficient Solar‐Powered Interfacial Evaporation, Water Remediation, and Waste Conversion Based on a Tumbler‐Inspired, All‐Cellulose, and Monolithic Design
Authors: He Jintao , Li Na , Wang Shuxue , Li Shuai , Li Jingjing , Yu Liangmin , Liu Shuang , Murto Petri , Xu Xiaofeng
Published: July 2022

The 3D steam generator with cold evaporation surface (CES) provides a means for high‐efficiency interfacial steam generation due to the low heat loss and continuous ambient energy input. However, the poor floating stability of CES steam generators when suffering wave slamming has limited their practical application in open water. Herein, a cellulose‐based monolithic aerogel integrated with three structural elements is developed inspired by tumblers, which can synchronously achieve outstanding antioverturning stability in waves and a high evaporation rate (4.21 kg m−2 h−1). A single‐stage solar water purification device is constructed based on the photothermal aerogel, which attains an ultra‐high daily water yield of ≈32.6 L m−2 and surpasses a large amount of single‐stage solar stills. The steam generator can also be used to purify wastewater containing Co2+ via adsorption. Gratifyingly, the Co3O4/C catalyst obtained from the pyrolysis of aerogels loaded with Co2+ exhibits good catalytic activity for carbon monoxide oxidation, demonstrating the potential for waste conversion. This work provides new insights into the design of solar steam generators used in open water, and offers a promising way for the disposal and utilization of contaminated steam generators after wastewater purification.
Mechanoresponsive Carbamoyloxime für die Aktivierung Sekundärer Amine in Polymeren
Authors: Campagna Davide , Göstl Robert
Published: July 2022

Mechanophore sind molekulare Einheiten, die in Polymere eingebaut werden und auf Kraft mit konstitutionellen, konfigurativen oder konformationellen Bindungsumlagerungen reagieren, um Funktionalität zu ermöglichen. Bis heute wurden bereits einige chemisch latente Motive durch mechanochemische Methoden in Polymeren aktiviert, aber die Erzeugung sekundärer Amine blieb unerforscht. Hier berichten wir über Carbamoyloxime als mechanochemische Schutzgruppen für sekundäre Amine. Wir zeigen, dass Carbamoyloxime eine kraftinduzierte homolytische Bindungsspaltung an der N−O‐Oximbindung in Polymeren eingehen und so das freie Amin erzeugen. Die Reaktion verläuft analog zu ihrem photochemischen Gegenstück über Carbamoyloxyl‐ und Aminylradikale. Schließlich wenden wir das Carbamoyloxim‐Motiv in einer kraftaktivierten organokatalytischen Knoevenagel‐Reaktion an. Wir glauben, dass diese Schutzgruppenstrategie universell für viele andere sekundäre und primäre Amine in Polymermaterialien angewendet werden kann.
Momomycin, an Antiproliferative Cryptic Metabolite from the Oxytetracycline Producer Streptomyces rimosus
Authors: Li Yuchen , Lee Seoung Rak , Han Esther J. , Seyedsayamdost Mohammad R.
Published: July 2022

Natural products provide an important source of pharmaceuticals and chemical tools. Traditionally, assessment of unexplored microbial phyla has led to new natural products. However, with every new microbe, the number of orphan biosynthetic gene clusters (BGC) grows. As such, the more difficult proposition is finding new molecules from well‐studied strains. Herein, we targeted Streptomyces rimosus, the widely‐used oxytetracycline producer, for the discovery of new natural products. Using MALDI‐MS‐guided high‐throughput elicitor screening (HiTES), we mapped the global secondary metabolome of S. rimosus and structurally characterized products of three cryptic BGCs, including momomycin, an unusual cyclic peptide natural product with backbone modifications and several non‐canonical amino acids. We elucidated important aspects of its biosynthesis and evaluated its bioactivity. Our studies showcase HiTES as an effective approach for unearthing new chemical matter from “drained” strains.
Disentangled ultrahigh molecular weight polyethylene thin film as a transparent substrate for flexible flat panel display
Authors: Shukla Devesh K. , Dey Anamika , Singh Ashish , Tripathi Sandeep N. , Bonda Sateesh , Saha Sukdeb , Iyer Parameswar Krishnan , Srivastava Vivek K. , Jasra Raksh Vir
Published: July 2022

The use of polymeric thin film as a substrate material in fabrication of flexible organic light‐emitting diodes (OLEDs) devices is well known. Polyethylene terephthalate (PET) and polyethylene naphtalate (PEN) thin films are used for such purpose commercially. In the present work, 10g of disentangled ultrahigh molecular weight polyethylene (D‐UHMWPE) was processed into 35 ± 5μ thin film by continuous solid state compaction process between two heated rollers of roll mill. The temperature of both rollers was kept at 125°C as well as 128°C and the thin‐film production rate was 1.5 m/min. Subsequently film was studied for substrate application in fabrication of flexible OLEDs. The primary requirement of OLED substrate material namely chemical stability, transparency, and dimensional stability of D‐UHMWPE thin film were studied. D‐UHMWPE film showed excellent chemical stability under various solvents (chloroform, chlorobenzene, dichlorobenzene, acetone, and isopropanol) treatments along with >80% transparency and dimensional stability up to 100 ± 10°C (machine and transverse directions 0.001% and 0% at 90°C and 0.003% and 0% at 110°C). Finally, OLED device was fabricated on D‐UHMWPE surface which showed excellent performance in terms of (light emitting) even when the devices were bended.
Enhancing toughness of poly(lactic acid) by regulating the hydroxyl value and viscosity of hydroxyl terminated polybutadiene
Authors: Ma Zhirui , Zhang Caili , Tang Duo , Yang Yang , Yang Fan , Zhao Min , Han Yu , Weng Yunxuan
Published: July 2022

Brittleness of poly(lactic acid) (PLA), a biocompatible and biodegradable polymer obtained from renewable and natural sources, hinders its widespread applications. This study provides a convenient and economical way to enhance the toughness of PLA by using hydroxyl terminated polybutadiene (HTPB) liquid rubber to modify PLA. Four types of HTPB with varied hydroxyl values and viscosities were used to prepare PLA/HTPB blends. The effects of HTPB content on the mechanical characteristics, phase structure, thermal and crystalline properties of the toughened blends were systematically investigated. For PLA/HTPB2‐5%, the elongation at break and impact strength was 87% and 58 kJ/m2, respectively, which was 12.8 and 3.5 times that of neat PLA. Due to the relatively lower hydroxyl value and suitable viscosity of HTPB2, PLA/HTPB2‐5% exhibited the best impact toughness and had the highest impact strength. When the content of HTPB exceeded 5%, the mechanical properties of PLA/HTPBs gradually decreased. This could be due to the gradual increase of particle size of the dispersed phase with increasing HTPB content, resulting in serious phase separation between the dispersed phase and continuous phase. The resultant PLA/HTPB2 composites with improved toughness could have potential applications in engineering materials thus enlarging the spectrum of applications for PLA.
People imitate others' dishonesty but do not intentionally search information about it
Authors: Leib Margarita
Published: July 2022

When people see that others lie for financial profit, they are more likely to lie themselves. But do people search for information about others' behavior in ethically tempting situations? And among those who search, what type of information do they search for? Specifically, do people search for information about others' dishonesty in particular, to justify their future transgressions, or do they search for information about others' behavior in general to learn about the descriptive social norm? Across four financially incentivized experiments (Ntotal = 2642), participants engaged in a task in which they could lie for profit. Before starting their task, participants could search for information about others' behavior in the same task. Results reveal that when people search for information, they do so in order to learn about the descriptive norm, not to intentionally learn about others' dishonesty. When the decision to search for information results in observing more dishonest others, participants become more dishonest themselves. Testing a boundary condition revealed that when information search is costly (vs. free), people search for less information, observe less dishonest others, and subsequently are less dishonest themselves. Findings suggest that in settings where people may act dishonestly, information about others behavior should be costly to obtain.
Integrating experience with databases, bioinformatics, and wet lab exercises for students in an introductory genetics course
Authors: Carroll David J.
Published: July 2022

Students often have no exposure to the incredible amount of genomic and proteomic data that is freely and easily accessible online. Becoming familiar with these resources, and seeing how they could be applied to a specific research question, is a prerequisite for students to apply them to their own scientific development. Many students have to “see it” and “do it” before they “get it.” This paper describes a teaching laboratory for undergraduate Genetics students that combines exploration of several publicly available databases with some simple bioinformatic exercises and “‘real” live experience in a wet lab exercise. The goal is to teach skills in applying genomic data to a real scientific question. In this exercise, students identify a target protein after exploring several protein and signal transduction databases, such as the Kyoto Encyclopedia of Genes and Genomes database. They then search for the encoding RNA in a newly available sea star mature egg transcriptome database and for the DNA in an existing sea star genome database. The students design primers against specific regions or domains in their target RNA and amplify these by reverse transcription PCR against RNA purified from fresh sea star eggs. The PCR reactions are analyzed by agarose gel electrophoresis. It is hoped that the combination of the computational biology exercises with the real lab work will excite the students and stimulate them to explore this exciting new biology further.
Current progress of cerebral organoids for modeling Alzheimer's disease origins and mechanisms
Authors: Sreenivasamurthy Sai , Laul Mahek , Zhao Nan , Kim Tiffany , Zhu Donghui
Published: July 2022

Alzheimer's disease (AD) is a progressive, neurodegenerative disease that has emerged as a leading risk factor for dementia associated with increasing age. Two‐dimensional (2D) cell culture and animal models, which have been used to analyze AD pathology and search for effective treatments for decades, have significantly contributed to our understanding of the mechanism of AD. Despite their successes, 2D and animal models can only capture a fraction of AD mechanisms due to their inability to recapitulate human brain‐specific tissue structure, function, and cellular diversity. Recently, the emergence of three‐dimensional (3D) cerebral organoids using tissue engineering and induced pluripotent stem cell technology has paved the way to develop models that resemble features of human brain tissue more accurately in comparison to prior models. In this review, we focus on summarizing key research strategies for engineering in vitro 3D human brain‐specific models, major discoveries from using AD cerebral organoids, and its future perspectives.
Profiling Heparan Sulfate‐Heavy Metal Ions Interaction Using Electrochemical Techniques
Authors: Shitrit Ariel , Mardhekar Sandhya , Alshanski Israel , Jain Prashant , Raigawali Rakesh , Shanthamurthy Chethan D. , Kikkeri Raghavendra , Yitzchaik Shlomo , Hurevich Mattan
Published: July 2022

Heparan sulfate glycosaminoglycans provides extracellular matrix defense against heavy metals cytotoxicity. Identifying the precise glycan sequences that bind a particular heavy metal ion is a key for understanding those interactions. Here, electrochemical and surface characterization techniques were used to elucidate the relation between the glycans structural motifs, uronic acid stereochemistry, and sulfation regiochemistry to heavy metal ions binding. A divergent strategy was employed to access a small library of structurally well‐defined tetrasaccharides analogs with different sulfation patterns and uronic acid compositions. These tetrasaccharides were electrochemically grafted onto glassy carbon electrodes and their response to heavy metal ions was monitored by electrochemical impedance spectroscopy. Key differences in the binding of Hg(II), Cd(II), and Pb(II) were associated with a combination of the uronic acid type and the sulfation pattern.
CYP2S1 and CYP2W1 expression is associated with patient survival in breast cancer
Authors: Aiyappa‐Maudsley Radhika , Storr Sarah J , Rakha Emad A , Green Andrew R , Ellis Ian O , Martin Stewart G
Published: July 2022

The cytochrome P450 family of enzymes metabolise a wide range of compounds and play important roles in breast cancer pathogenesis due to their involvement in estrogen metabolism and the production of carcinogenic metabolites during this process. The orphan CYPs, CYP2S1, and CYP2W1 are reportedly upregulated in breast cancer. However, their expression and association with clinicopathological and survival parameters have not been previously assessed in a large cohort of breast cancers. Protein expression of CYP2S1 and CYP2W1 was assessed in early‐stage invasive breast cancers (n = 1,426) using immunohistochemistry and correlated with various clinicopathological parameters and survival. mRNA expression of CYP2S1 and CYP2W1 was also assessed in the Molecular Taxonomy of Breast Cancer International Consortium (METABRIC) cohort. Low nuclear and cytoplasmic CYP2S1 was significantly associated with high‐grade tumours (p ≤ 0.009), intermediate Nottingham prognostic index (NPI) group (p ≤ 0.025), high mitotic frequency (p ≤ 0.002), human epidermal growth factor receptor 2 (HER2)‐negative disease (p ≤ 0.011), and ductal carcinoma (p ≤ 0.022). Cytoplasmic CYP2S1 was additionally associated with patients ≥50 years (p < 0.001), estrogen receptor (ER)‐positive tumours (p = 0.011), and high nuclear pleomorphism (p = 0.003). Low cytoplasmic CYP2W1 was significantly associated with patients ≥50 years (p = 0.002), HER2‐negative disease (p = 0.003), intermediate NPI (p = 0.013), and mitosis (p = 0.009). Low cytoplasmic CYP2S1 was significantly associated with adverse breast cancer specific survival (p = 0.034), which remained so in multivariate analysis (hazard ratio [HR]: 0.639; 95% confidence interval [CI]: 0.483–0.846; p = 0.002). Low nuclear CYP2W1 was significantly associated with adverse breast cancer specific survival (p = 0.012), with significance also maintained in multivariate analysis (HR: 0.677; 95% CI: 0.510–0.898; p = 0.007). No associations with survival were observed in the METABRIC cohort. CYP2S1 and CYP2W1 are associated with patient survival in breast cancer and may be important prognostic biomarkers.
N‐Heterocyclic Carbene (NHC) Silver Complexes as Versatile Chemotherapeutic Agents Targeting Human Topoisomerases and Actin
Authors: Mariconda Annaluisa , Iacopetta Domenico , Sirignano Marco , Ceramella Jessica , Costabile Chiara , Pellegrino Michele , Rosano Camillo , Catalano Alessia , Saturnino Carmela , El‐Kashef Hussein , Aquaro Stefano , Sinicropi Maria Stefania , Longo Pasquale
Published: July 2022

In recent years, the number of people suffering from cancer has risen rapidly and the World Health Organization and U.S. and European governments have identified this pathology as a priority issue. It is known that most bioactive anticancer molecules do not target a single protein but exert pleiotropic effects, simultaneously affecting multiple pathways. In our study, we designed and synthesized a new series of silver N‐heterocyclic carbene (NHC) complexes [(NHC)2Ag]+[AgX2]− (X=iodide or acetate). The new complexes were active against two human breast cancer cell lines, MCF‐7 and MDA‐MB‐231. These compounds showed multiple target actions as anticancer, by inhibiting in vitro the activity of the human topoisomerases I and II and interfering with the cytoskeleton dynamic, as also confirmed by in silico studies. Moreover, the antimicrobial activity of these silver complexes was studied against Gram‐positive/negative bacteria. These dual properties provide a two‐tiered approach, making these compounds of interest to be further deepened for the development of new chemotherapeutic agents.
Addressing eating disorders in primary care: Understanding screening recommendations and opportunities to improve care
Authors: Peat Christine M. , Feltner Cynthia
Published: July 2022

Objective

For the first time in its history, the United States Preventive Services Task Force (USPSTF) published a recommendation on screening for eating disorders among adolescents and adults in primary care. The current manuscript provides an overview of the USPSTF recommendation, screening principles, and suggestions for clinical and research efforts.

Method

The USPSTF based their recommendations on a rigorous systematic review of the evidence on routine screening for eating disorders. Eligible studies included studies of screening test accuracy and controlled trials of screening or interventions for eating disorders in screen‐detected or previously untreated eating disorders. The current manuscript briefly summarizes the results of this evidence review which are published in full elsewhere and focuses on providing interpretation of the recommendations by clarifying the scope and methodology of the USPSTF.

Results

Fifty‐seven studies were included in the evidence review. Seventeen studies evaluated screening test accuracy and 40 trials evaluated interventions among populations with previously untreated eating disorders. No studies directly assessed the benefits and harms of screening. The evidence review highlights important gaps in our knowledge regarding eating disorders in primary care. The authors provide recommendations for future studies in light of these evidence gaps and propose specific clinical strategies to improve care for those with eating disorders who present to primary care.

Discussion

Primary care can play an important role in the early detection of eating disorders, but data are needed to more fully understand the potential benefits and harms of routine screening in this setting.

Public Significance

There are gaps in the evidence regarding the benefits and harms of eating disorder screening in primary care. Future studies are needed to improve certainty about the net benefit of screening. Of particular importance are studies that compare routine screening to usual care (no screening). Current providers may benefit from tailored eating disorders education and training, practical tools, and integration of mental health services in primary care.
Electrical cardioversion of atrial arrhythmias with cardiac amyloidosis in the era of direct oral anticogulants
Authors: Touboul Olivier , Algalarrondo Vincent , Oghina Silvia , Elbaz Nathalie , Rouffiac Segolene , Hamon David , Extramiana Fabrice , Gandjbakhch Estelle , D'Humieres Thomas , Marijon Eloi , Dhanjal Tarvinder S. , Teiger Emmanuel , Damy Thibaud , Lellouche Nicolas
Published: July 2022

Aims

Atrial fibrillation (AF)/atrial flutter is common during cardiac amyloidosis (CA). Electrical cardioversion (EC) is a strategy to restore sinus rhythm (SR). However, left atrial thrombus (LAT) represents a contraindication for EC. CA patients with AF/atrial flutter have a high prevalence of LAT. We aimed to evaluate EC characteristics, LAT prevalence and risk factors, and AF/atrial flutter outcome in CA patients undergoing EC, predominantly treated with direct oral anticoagulants (DOACs).

Methods and results

All patients with CA and AF/atrial flutter referred for the first time to our national referral centre of amyloidosis for EC from June 2017 to February 2021 were included in this study. In total, 66 patients (median age 74.5 [70;80.75] years, 67% male) were included with anticoagulation consisted of DOAC in 74% of cases. All patients underwent cardiac imaging before EC to rule out LAT. EC was cancelled due to LAT in 14% of cases. Complete thrombus resolution was observed in only 17% of cases. The two independent parameters associated with LAT were creatinine [hazard ratio (HR) = 1.01; confidence interval (CI) = 1.00–1.03, P = 0.036] and the use of antiplatelet agents (HR = 13.47; CI = 1.85–98.02). EC acute success rate was 88%, and we observed no complication after EC. With 64% of patients under amiodarone, AF/atrial flutter recurrence rate following EC was 51% after a mean follow‐up of 30 ± 27 months.

Conclusions

Left atrial thrombus was observed in 14% of CA patients listed for EC and mainly treated with DOAC. The acute EC success rate was high with no complication. The long‐term EC success rate was acceptable (49%).