bluuebunny/crossref_metadata_2025 huggingface dataset:
Fluide Mischsysteme unter hohem Druck. Phasengleichgewichte und kritische Erscheinungen in den binären Systemen Cyclohexan‐H2O, n‐Heptan‐H2O, Biphenyl‐H2O und Benzol‐D2O bis 420°C und 3000 bar
Authors: Bröllos K. , Peter K. , Schneider G. M.
Published: November 2023

In einer optischen Hochdruckmeßzelle mit einem Saphirfenster und Magnetrührung wurden die Zweiphasengleichgewichte binärer fluider Mischungen von Cyclohexan, n‐Heptan und Biphenyl mit H2O sowie Benzol mit D2O zwischen 260 und 420°C bis maximal 3000 bar ausgemessen und Teile der kritischen Kurven bestimmt.

Bei Cyclohexan‐H2O geht der am kritischen Punkt des reinen H2O beginnende Zweig der kritischen Kurve durch ein Temperaturminimum bei 346 ± 1°C und 355 ± 5 bar und verläuft dann steil zu steigenden Temperaturen und Drucken. Die kritischen Kurven der Systeme n‐Heptan‐H2O und Benzol‐D2O zeigen einen qualitativ ähnlichen Verlauf und damit ein Phasenverhalten, wie es in der Literature den sogenannten „Gas‐Gas‐Gleichgewichten”︁ zugeordnet wird, während bei Biphenyl‐H2O Flüssig‐Flüssig‐Gleichgewichte auftreten.

Diese Messungen passen sich in frühere eigene Versuche ein, das Phasenverhalten wäßriger KW‐Lösungen phasentheoretisch zu deuten.
Über die Elektronenzustände von NO‐Indigo und 2.2′‐Bis‐benzimidazolyl
Authors: Serafimov O. , Seiffert W. , Kräßig R. , Zimmermann H.
Published: November 2023

Die Elektronenzustände von 2.2′‐Bis‐benzimidazolyl I, NO‐Indigo II, Benzimidazol III und Benzimidazol‐N‐oxid IV wurden in PPP‐Näherung berechnet und untereinander korreliert. Die Parameter haben wir an den Spektren von III und IV justiert und auf die Berechnung von I und II übertragen. Nach den Berechnungen ist NO‐Indigo eine farblose bis gelbe, bei Zimmertemperatur diamagnetische Substanz. Dieses Ergebnis steht im Widerspruch zu Literaturangaben. Danach soll fester NO‐Indigo eine violette bis schwarze, bei Zimmertemperatur paramagnetische Substanz sein. Experimentelle Untersuchungen machen es wahrscheinlich, daß die als NO‐Indigo beschriebene Substanz nicht das Oxydationsprodukt von 2.2′‐Bis‐benzimidazolyl I, sondern des isomeren Fluoflavins VII ist und damit nicht die diskutierte Struktur besitzt.
Zur Temperatur‐ und Druckabhängigkeit der thermodynamischen Eigenschaften von hochpolymeren Lösungen. Die Anwendung des Theorems der überein‐stimmenden Zustände
Authors: Lechner M.
Published: November 2023

Sowohl die Theorie des ausgeschlossenen Volumens, als auch die von Flory et al. und Patterson et al. entwickelten Theorien auf der Grundlage des freien Volumens sind nicht in allen Fällen in der Lage, die von uns durchgeführten Streulichtexperimente an hochmolekularen Lösungen in Abhängigkeit von Temperatur und Druck quantitativ zu deuten. Wir haben daher den Versuch unternommen, auf der Grundlage des Theorems der übereinstimmenden Zustände die thermodynamischen Eigenschaften von hochpolymeren Lösungen zu berechnen. Für unsere bisher vermessenen Systeme erhalten wir gute Übereinstimmung mit allen experimentellen Befunden. Insbesondere gelingt es auch, die relative Größe der Energiepotentiale ε*11 ε*22 und ε*22 (Potentiale für die van der Waalsschen Kräfte zwischen zwei Segmenten) sowie den sogenannten “Strukturparameter” (zurückzuführen auf die Valenzkräfte zwischen zwei Segmenten) zu bestimmen.
Viskositätsmessungen an konzentrierten Elektrolytlösungen (Der Einfluß von Ionen auf die Wasserstruktur)
Authors: Ebert G. , Wendorff J.
Published: November 2023

Die Viskosität konzentrierter Elektrolytlösungen wird u. a. von dem Einfluß der Ionen auf die Beweglichkeit der Wassermolekeln (“Strukturbrechung” und “Strukturbildung”) bestimmt. In der vorliegenden Arbeit wird versucht, die viskositätserhöhende Wirkung der gelösten Ionen einschließlich ihrer primären Hydrathülle zu berücksichtigen. Hierdurch soll der tatsächliche strukturbildende bzw. strukturbrechende Effekt der Ionen gegenüber dem Wasser erfaßt werden. Erst nach dem Anbringen dieser Korrekturen kann man hierüber zuverlässige Aussagen aus Viskositätsmessungen erhalten. Dabei ergibt sich, daß der strukturbrechende Charakter der untersuchten Elektrolyte sehr viel ausgeprägter ist, als aufgrund der unkorrigierten Viskositätsmessungen und auch anderer Meßverfahren angenommen wird. Daß die Wassermolekeln der primären Hydrathülle gemäß der Auffassung zahlreicher Autoren in der hier interessierenden Zeitskala dem Ion fest zugeordnet sind, ergibt sich auch aus der Aktivierungsenergie der Viskosität dieser Lösungen und den hiermit berechneten Zeiten zwischen zwei Platzwechseln.

Die Lage der korrigierten relativen Viskosität ζrel,korrT und die der Aktivierungsenergie gegenüber dem Bezugswert des reinen Wassers stimmt weitgehend überein. Dies weist darauf hin, daß die aufgrund unserer Vorstellungen anrel angebrachten Korrekturen sinnvoll sind. Damit ergibt sich ferner, daß nur in den Lösungen weniger Elektrolyte wie z. B. Li2SO4 und Li‐acetat die Beweglichkeit der Wassermolekeln außerhalb der primären Hydrathülle gegenüber dem reinen Wasser herabgesetzt ist, also tatsächlich Strukturbildung vorliegt, bzw. überwiegt.
Investigations of Surface Processes with the Atom‐Probe Field Ion Microscope
Authors: Müller Erwin W.
Published: November 2023

Field ion microscopy ranges from the study of lattice defects to biomolecules. The atom‐probe adds versatility by permitting the mass spectrometric identification of single atom spots selected by the observer. Noble image gas atoms are found to be adsorbed at the specimen surface under normal operating conditions of the FIM. Binding energies are derived and a new mechanism of field ionization by electron tunneling through the adsorbate atom is evidenced. In the presence of the field the substrate metal forms surface molecules with noble gases as well as with the common gases, while field‐induced dissociation of adsorbed CO is also established. A modified atom‐probe with partial retardation permits discrimination of energy deficits of field evaporating species from satellite signals due to hydride formation. Ion energy deficits are mostly caused by premature field evaporation, while the losses due to excitation of surface plasmons as suggested by Lucas do not seem to have the predicted magnitude.
Wechselwirkung von Wasserstoff mit einer Nickel (110)‐Oberfläche
Authors: Ertl G. , Küppers D.
Published: November 2023

Die Wechselwirkung zwischen Wasserstoff und einer reinen Ni(110)‐Oberfläche wurde in einer UHV‐Apparatur mittels Messung des Kontaktpotentials, thermischer Desorption, LEED und Massenspektrometrie untersucht. Die Adsorption erfolgt zunächst in einem eindimensional geordneten α‐Zustand mit einer Adsorpticnsenergie von 19,5 kcal/mol, die weitgehend unabhängig vom Bedeckungsgrad ist. Dieser α‐Zustand wandelt sich langsam in einen um 10 kcal/mcl fester gebundenen β‐Zustand mit zweidimensionaler Ordnung (1 · 2‐Struktur) um. Die Kinetik der Adsorption und Desorption wurde mit einem Relaxationsverfahren über die Messung des Kontaktpotentials im Detail studiert. Die H2/D2‐Austauschreaktion verläuft bei Zimmertemperatur sehr schnell und nach dem Eley‐Rideal‐Mechanismus, wobei sich der Übergang α → β auch in einem Abfall der Austauschgeschwindigkeit bemerkbar macht.
Kalorimetrische Messungen der Chemisorptionswärmen von Gasgemischen
Authors: Kölbel H. , Roberg H.
Published: November 2023

An reduzierten Eisenfällungskatalysatoren mit und ohne Zusatz von 0,2 Gewichtsprozent K2CO3 wurden Adsorptions‐ und Desorptionswärmen bei simultaner Sorption von CO/H2‐Gemischen verschiedener Zusammensetzung im Druckbereich 10−2 bis 350 Torr und 35°C mit dem Mikrocalorimeter “Calvet“ untersucht. Die Gasphase wurde laufend mit einem Quadrupol‐Massenspektrometer analysiert. Für die Reingase CO bzw. H2 ergeben sich an undotierten Katalysatoren gleiche Adsorptionswärmen, während an Katalysatoren mit K2CO3 für CO 3–6 kcal/mol höhere Wärmen gemessen wurden. Bei simultaner Adsorption beider Gase werden erheblich größere Gasmengen auf der Oberflächeneinheit adsorbiert und auch erheblich größere Adsorptionswärmen gemessen, als aus der Addition der Werte beider Einzelkomponenten bei gleichen Bedingungen berechenbar wäre. Auch hier sind an dotierten Katalysatoren die Adsorptionswärmen um etwa 6 kcal/mol größer. Darüber hinaus desorbiert nach gewisser Zeit des Abpumpens nur noch ein Gasgemisch der Zusammensetzung CO:H2 = 1:1 unabhängig von der Zusammensetzung des zur Adsorption angebotenen Gasgemisches.
The Vapour Pressure Curve of Liquid Potassium up to the Critical Point
Authors: Freyland W. F. , Hensel F.
Published: November 2023

The vapour pressure curve of liquid potassium was measured up to the critical point which was found at Tcrit = 1925 °C ± 30 and Pcrit = 155 ± 15 bar. Using these vapour pressure data and existing density data of the vapour and liquid at saturation pressure the vaporization entropy of potassium as a function of temperature was determined.

The vapour pressure was determined by the observation of the drastic change in the electrical conductivity and the thermoelectric power when the liquid metal is evaporated. Since no electrically insulating container material compatible with alkali metals is available, metallic tungsten‐rhenium container were used as conductors in parallel with the fluid metal sample. This newly developed method can also be applied to other corrosive liquid metals.
Solvation Dynamics in Macromolecular Solutions as Studied by NMR Relaxation
Authors: Brüssau R. G. , Sillescu H.
Published: November 2023

2H and 35C1 relaxation times have been determined in dilute CDCI3 and D2O solutions of polyvinylpyrrolidone. The results are interpreted in terms of a two state model of solvent solute interaction. The theory of spin lattice relaxation in two state systems with rapid exchange has been extended to allow for anisotropic rotational motions of the solvent molecules. When applied to the results in CDCI3 solutions, the model treatment yields the life time of hydrogen bonding in the solvated state, and the rotational diffusion constant for rotation around the hydrogen bond. Activation energies are obtained from the temperature dependence of the deuterium relaxation times.
Die elektrische Leitfähigkeit geschmolzener Alkalinitrate bei hohen Drücken. I. Der Druckbereich bis 5,5 kbar
Authors: Quist A. S. , Würflinger A. , Tödheide K.
Published: November 2023

Die spezifische elektrische Leitfähigkeit der geschmolzenen Alkalinitrate wurde im Druckbereich bis 5,5 kbar gemessen. Die geschmolzenen Salze wurden dabei in einer offenen Leitfähigkeitsmeßzelle aus Pyrexglas in einem innenbeheizten Hochdruckgefäß komprimiert, wobei der Druck durch Argon auf das Salz übertragen wurde. Aus PVT‐Daten und den gemessenen spezifischen Leitfähigkeiten wurden die molaren Leitfähigkeiten der Salze berechnet. Der Logarithmus der molaren Leitfähigkeit ist für alle Nitrate eine lineare Funktion sowohl des Druckes wie auch der reziproken absoluten Temperatur bei konstantem Druck und bei konstantem Volumen. Das Aktivierungsvolumen steigt und die isochore Aktivierungsenergie fällt monoton mit zunehmender Größe des Alkaliions. Es zeigt sich, daß keines der für geschmolzene Salze gebräuchlichen Modelle die experimentell gefundene Temperatur‐ und Dichteabhängigkeit des Ladungstransports in den geschmolzenen Alkalinitraten richtig zu beschreiben vermag.
Promotierung der Feldionisation an organischen Emittern durch Benzol
Authors: Röllgen F. W. , Beckey H. D.
Published: November 2023

Die Promotierung der Feldionisation von Molekülen durch Benzol wird bei organischen Emittern durch einen Anstieg der Feldstärke in den Emissionsbereichen der Emitteroberfläche hervorgerufen. Die Zunahme der Feldstärke resultiert aus einer elektrischen Aufladung der organischen Nadeln durch feldadsorbierte Benzolionen. Bei dieser ionischen Feldadsorption von Benzol erfolgen Elektronenübergänge nicht nur ins Valenzband, sondern auch in Akzeptorniveaus des Leitfähigkeitsbandes. Die beobachtete Desaktivierung der Benzolpromotierung durch Feldimpulse läßt sich auf eine Feldimpulsdesorption von Benzoloberflächenionen zurückführen.
Electrochemical methods for diffusion measurements
Authors: Züchner H. , Boes N.
Published: November 2023

The hydrogen pressure at the surface of a metal sheet, e.g. a palladium foil immersed in an electrolyte, can be measured by means of the electrochemical potential. With proper activation of the metal surface the partition equilibrium between hydrogen dissolved in the metal and in the electrolyte prevails at all times. This yields the relationship between the atomic ratio H/Me within the metal and the electrochemical potential.

On this basis various techniques have been developed for the measurement of diffusion coefficients of hydrogen in Pd. ‐ These methods are described in a short review.

The great advantage of electrochemical methods compared to other techniques will become clear by a more detailed description of two electrochemical time‐lag methods, the step and the pulse technique, which have been used to investigate the diffusion of hydrogen and deuterium in Pd and Pd/Ag alloys up to 60 percent silver content and more recently in Ta.

With simple equipment the dependence of the diffusion coefficient on hydrogen concentration from extremely low pressures up to one atmosphere could be measured very precisely. The values obtained with these convenient methods range from 10−6 cm2 s−1 in pure Pd to 10−10 cm2 s−1 in Pd/Ag 40/60. Furthermore the methods are sensitive enough to yield the differences in diffusion coefficients of H and D in these alloys. The isotope effect will not be discussed here. A more detailed interpretation is given in following papers.
Diffusion of hydrogen in metals
Authors: Birnbaum H. K. , Wert C. A.
Published: November 2023

Published measurements of the diffusion of hydrogen in fcc metals are summarized with particular emphasis on the isotope effect. The observations are generally consistent with the usual rate theory model but with the energy levels in both the equilibrium site and the saddle point quantized according to an Einstein oscillator. Not all data fit this scheme, however, diffusion in Pd being a notable exception. Published work for the bcc metals shows much less consistency; surface effects and internal trapping at defects and impurities are apparently of over‐riding importance. A summary of measurements of diffusion of hydrogen in liquid metals is also made.
On the electronic structure of hydrogen in metals
Authors: Friedel J.
Published: November 2023

The possible electronic structure of hydrogen in ordinary metals and alloys, transitional metals and rare earth metals is discussed, with an emphasis on dilute solutions.
Magnetic properties of rare earth hydrides
Authors: Wallace W. E.
Published: November 2023

Magnetic measurements on fully hydrogenated rare earth metals give no indication of magnetic ordering at temperatures down to 4 °K, whereas the corresponding elemental rare earth metals, except Pr, order at temperatures ranging from 19°K for Nd to 289 °K for Gd. The results are consistent with electrical resistivity measurements which indicate that these hydrides are not metallic conductors. Since the RKKY interaction is inoperative in the hydrides, ordering temperatures are depressed below 4°K. Detailed analysis of the paramagnetic behavior of PrH2 shows that experiment is consistent only with the anionic model for hydrogen in rare earth hydrides. Rare earth dihydrides, which are metallic conductors, do show magnetic ordering at temperatures ranging from 8°K, for HoH2 and DyH2, to 40°K, for TbH2, EuH2, alone among the dihydrides which order, becomes ferromagnetic.

Rare earth intermetallics of the formula RT2 and RT5 (T = Co or Ni) absorb hydrogen with noticeable effect on their magnetic and electrical properties. Virgin samples of PrCo2 and NdCo2 order at 45 and 116 °K, respectively. After degassing under ultrahigh vacuum conditions at elevated temperature, these materials fail to exhibit magnetic ordering down to 4°K. A discussion is given of factors which probably bring about this striking sensitivity to hydrogen concentration.
Ionen‐Halleffekt in α‐AgJ
Authors: Funke K. , Hackenberg R.
Published: November 2023

Messungen des Ionen‐Halleffektes wurden in polykristallinem α‐AgJ ausgeführt. Hierzu wurde die sogenannte Kreuzmodulationsmethode verwendet. Aus den Meßergebnissen erhält man die Hallbeweglichkeit der Silberionen. Sie ist innerhalb der Fehlergrenzen identisch mit der Driftbeweglichkeit, die man unter der Annahme vollständiger Fehlordnung des Kationengitters aus der Leitfähigkeit berechnet.
Potentialabhängigkeit von Elektrosorptionsgleichgewichten und die Elektrosorptionswertigkeit γ
Authors: Vetter K. J. , Schultze J. W.
Published: November 2023

Die Elektrosorption, d. h. die Adsorption in der inneren Helmholtzschicht an der Phasengrenze Elektrode/Elektrolyt wird in Abhängigkeit von der Potentialdifferenz Δϕ in der starren Doppelschicht behandelt. Die Potentialabhängigkeit wird durch eine Elektrosorptionswertigkeit Γ beschrieben, die durch γF=(δμs/δΔϕ)&Γadbei konstantem Oberflächenüberschuß Γadder elektrosorbierten Substanz definiert wird. Diese Gleichung entspricht der Nernstschen Gleichung mit einer nichtganzzahligen Wertigkeit γ Für den Fall eines Fremdelektrolytüberschusses gilt angenähert die einfachere Beziehung ΓF=(δμs/δΔϕ)Γadin der anstelle des chemischen Potentials in der äußeren Helmholtzschicht und anstelle von Δ das chemische Potential in der Lösung μsund das Elektrodenpotential verwendet werden.

Bei der Interpretation von Γ wird berücksichtigt: das räumlich begrenzte Eindringen des Adsorbats in die starre Doppelschicht (Geometriefaktorg), der Ladungsübergang (nichtganzzahliger partieller Ladungsübergangskoeffizient λ), die orientierte Adsorption von Dipolmolekeln (Kad) und die Verdrängung von Solvatmolekeln (Kw) und die Änderung der kapazitiven Energie bei der Elektrosorption (δD/δΓad). Die Potentialabhängigkeit von γ ist durch den kapazitiven Term gegeben.

Unter Verwendung der Elektrosorptionswertigkeit γ ergibt sich eine elektrochemische Adsorptionsisotherme, aus der spezielle Gleichungen (Langmuirisotherme, Temkinisotherme) abgeleitet werden.
Überschneidungspunkte und Übergänge zwischen Grundzuständen verschiedener Spin‐Multiplizität bei Komplexverbindungen
Authors: König E.
Published: November 2023

Die energetischen Verhältnisse an Überschneidungspunkten von Grundzuständen werden sowohl innerhalb der Ligandenfeldtheorie als auch unter Benutzung molekularer Potentialkurven diskutiert. Eine Übersicht der wichtigsten experimentellen Ergebnisse an 5T2g ‐ 1A1g‐Übergängen in geeigneten Eisen(II)‐Komplexen wird gegeben. Dabei ermöglichen Untersuchungen des 57Fe Mössbauer‐Effektes über den Temperaturbereich 4,2‐300° detaillierte Aussagen über Ausmaß des Überganges, Bruchteil der permanent paramagnetischen (5T2g) Moleküle, Debye‐Waller‐Faktoren, elektronische Relaxation zwischen den Grundzuständen 5T2g und 1A1g und schließlich über den Mechanismus des Überganges. Anionen und Solvatmoleküle haben keinen direkten Einfluß auf die beobachteten Übergange.
Infrared Internal Reflection Spectra of Crystalline Quartz I. Hydroxyl Groups
Authors: Gallei E.
Published: November 2023

In the O ‐ H‐stretching region three sharp symmetrical absorption bands at 3689 ± 1, 3650 ± 1, and 3620 ± 1 cm−1 and a broad band at 3410 cm−1 are observed on ground α‐quartz by Internal Reflection Spectroscopy (IRS). The bands at 3689 and 3620 cm−1 are correlated to two types of free surface hydroxyl groups, at 3650 cm−1 to isolated adsorbed water molecules and at 3410 cm−1 to liquid or hydrogen bonded water.

Vacuum treatment at different temperatures (50 ‐ 250°C), examination of the region of deformation vibrations and isotopic exchange with heavy water confirmed these assignments. From the results it is concluded that the surface of crystalline α‐quartz seems to be more like γ‐Al2O3 than it is like amorphous SiO2, because two spectroscopically distinct types of free hydroxyl groups are observed.
Zur geometrischen Darstellung von Phasengleichgewichten
Authors: Schmalzried H. , Pelton A. D.
Published: November 2023

Zum Zwecke einer möglichst rationellen und optimalen Darstellung thermodynamischer Information in Mehrkomponentensystemen werden die drei Typen zweidimensionaler Gleichgewichtsphasendiagramme hinsichtlich ihrer Topologie untersucht. Diese Typen sind 1. Diagramme, in denen zwei Potentialfunktionen gegeneinander aufgetragen sind, 2. Diagramme, in denen eine Potentialfunktion durch das Verhältnis konjugierter Extensivgrößen ersetzt wurde und 3. Diagramme, in denen beide Potentialfunktionen durch das Verhältnis konjugierter Extensivgrößen ersetzt wurden.

Im zweiten Teil der vorliegenden Arbeit werden die allgemeinen Überlegungen zur Berechnung und Darstellung ternärer Zustandsdiagramme für Systeme der Art A‐B‐X benutzt. Es zeigt sich, daß aus den vorgeschlagenen Darstellungen, insbesondere den log px2 ‐ nA/(nA + nB)‐Diagrammen, die topologisch vollständig den bekannten T ‐ xi‐Diagrammen binärer Systeme gleichen, praktisch wichtige Schlüsse zu ziehen sind. Die bearbeiteten ternären Systeme sind Co ‐ Ni‐ O, Cu ‐ Ni‐ S, Sn ‐ Pb ‐ Cl, Fe ‐ Cr ‐ O.
ESR‐spektroskopische Untersuchungen über Radikaldianionen substituierter Phenanthroimidazole
Authors: Kiesele Herbert , Volkamer Klaus , Zimmermann Herbert
Published: November 2023

Es werden ESR‐Spektren von Radikaldianionen analysiert, die sich von 4,5,(9′10′)‐Phenanthroimidazolen ableiten. Sie bilden sich bei Behandlung geeigneter Imidazole mit Alkalimetallen in inerten Lösungsmitteln. Wie aus den ESR‐Spektren und Spindichteberechnungen hervorgeht, hält sich das Radikalelektron bei den 2‐Arylverbindungen der Reihe nicht im 2‐Arylrest auf. Wir nehmen an, daß 2‐Arylrest und Heterocyclus zueinander orthogonal sind. Die Orthogonalität der Molekülreste läßt sich auf sterische Hinderung durch Ionenpaarbildung zurückführen. Die Ionenpaare wurden ESR‐spektroskopisch nachgewiesen.

Die Elektronenstrukturen der Radikaldianionen und der isoelektronischen Phototetrazolinyle werden untereinander verglichen.
Kinetics of the One Dimensional Lattice and Triplet Closure
Authors: Rawlings Philip K. , Schneider Friedemann W.
Published: November 2023

It is proved that, for the special case of infinitesimal perturbations only, triplet closure leads to an exact description of cooperative quasi‐phase transitions of linear macromolecules of infinite chainlength when the reaction starts from a Zimm‐Bragg equilibrium state. We use an expansion method that is similar to, but more accurate that Craig and Crother's matrix iteration procedure to calculate the time history for any size perturbation from an initial to the final equilibrium state. As a result of our numerical integrations we conclude in agreement with other workers that for finite perturbations triplet closure is highly accurate but not exact in describing the kinetic behavior. This conclusion is arrived at from comparison of numerical calculations of closure levels of sequences of two, three and four lattice sites with each other and with the “exact” Monte Carlo method.
Trajectories in Ion‐Molecule Reactions
Authors: Tully John C.
Published: November 2023

An appraisal of the classical trajectory method as a tool for studying ion‐molecule reactions is presented. The method has recently been extended to incorporate nonadiabatic processes such as charge transfer. This approach has been applied to two fundamental ion‐molecule reactions, Ar+ + H2 and H+ + H (and isotopic variants). Important conclusions concerning the dynamics of these reactions are discussed. Detailed comparisons with the results of molecular beam experiments are included. The agreement between the computer simulations and experiment is indicative of a very promising future for the trajectory method. Provided that reliable potential energy surfaces can be constructed, the method should be capable of accurate prediction of most reaction attributes, e.g. reaction rates, product internal energy distributions, etc. In addition, it can provide unambiguous information about reaction mechanisms that cannot be obtained by experimental means, and it can be used to assess the validity of models which employ simplified forces or dynamics. Possible directions are suggested for future work in this area.
Collisional Energy Transfer in Thermal Unimolecular Reactions
Authors: Troe J.
Published: November 2023

The master equation of a thermal unimolecular reaction in the low pressure limit is solved analytically for a three‐parameter, versatile model of the collisional transition probabilities. This model is compared with the statistical theory of energy exchange. The overall rate constant of the reaction is found to depend predominantly on the mean energy Δ E transferred per collision and only slightly on shape factors of the collisional transition probability. The theory allows for a direct, simple derivation of Δ E from thermal unimolecular reaction data.
A simple tool for the synchronous differentiation of human induced pluripotent stem cells into pancreatic progenitors
Authors: Kim Mee‐Hae , Thanuthanakhun Naruchit , Kino‐oka Masahiro
Published: November 2023

Efficient differentiation of human induced pluripotent stem cells (hiPSCs) into functional pancreatic cells holds great promise for diabetes research and treatment. However, a robust culture strategy for producing pancreatic progenitors with high homogeneity is lacking. Here, we established a simple differentiation strategy for generating synchronous iPSC‐derived pancreatic progenitors via a two‐step method of sequential cell synchronization using botulinum hemagglutinin (HA), an E‐cadherin function‐blocking agent. Of the various methods tested, the first‐step synchronization method with HA exposure induces a synchronous switch from E‐ to N‐cadherin and N‐ to E‐cadherin expression by spatially controlling heterogeneous cell distribution, subsequently improving their competency for directed differentiation into definitive endodermal cells from iPSCs. The iPSC‐derived definitive endodermal cells can efficiently generate PDX1+ and NKX6.1+ pancreatic progenitor cells in high yields. The PDX1+ and PDX1+/NKX6.1+ cell densities showed 1.6‐ and 2.2‐fold increases, respectively, compared with those from unsynchronized cultures. The intra‐run and inter‐run coefficient of variation were below 10%, indicating stable and robust differentiation across different cultures and runs. Our approach is a simple and efficient strategy to produce large quantities of differentiated cells with the highest homogeneity during multistage pancreatic progenitor differentiation, providing a potential tool for guided differentiation of iPSCs to functional insulin‐producing cells.
Substitution Sur le Mono, di et Trichloronitroethylene Syntheses de Derives du Nitroacetaldehyde et Des Acides Nitro et Chloronitro Acetiques
Authors: Francotte E. , Verbruggen R. , Viehe H. G. , van Meerssche M. , Germain G. , Declercq J. P.
Published: November 2023

Nitroacetylenes possess an activated triple bond both for nucleophilic additions and cycloadditions (1,2). ß Mono‐ and dichloronitroethylenes which are synthetic equivalents of the nitroacetylene and chloronitroacetylene display also interesting reactivity patterns, due to the presence of a nitro group (4,5).
Preparation and some reactions of α,β‐unsaturated lactones synthesis of cyclopropanes related to chrysanthemic acid
Authors: Kristensen J. , Thomsen I. , Lawesson S. ‐O.
Published: November 2023

2‐Bromo‐2‐methylpropylidene malonates, 3, undergo thermal ringclosure reactions to give 3‐alkoxycarbonyl‐5,5‐dimethyl‐2(5H)‐furanones, 4. Michael addition of Grignard reagents and thiols to 4a, subsequent ethoxycarbonyl elimination, treatment of 8 with SOCl2 and EtOH and, finally, ringclosure lead to cyclopropanes. Sodium cyanide is also smoothly added to 4a. Addition of NaCN, C2H5ONa and ϕSNa to 3 gives the cyclopropanes, 17. Subsequent ethoxycarbonyl elimination of 17a produces 18a and 19a, which are related to chrysanthemic acid.
Title IX ruling offers valuable guidance for addressing off‐campus violence
Authors: Lyerly Eric
Published: November 2023

There has been another installment in the long line of court cases examining whether colleges and universities are liable for off‐campus misconduct by students. Traditionally, these cases have involved tort/negligence claims and explored whether there is a special (legal) relationship between postsecondary institutions and their students. Such cases are finding new life in Title IX law, specifically deliberate indifference claims.
ANA‐negative severe lupus‐like presentation: Is it lupus or not?
Authors: Li Shuangxi , Bian Qi
Published: November 2023

Key Clinical Message

Systemic lupus erythematosus is difficult to diagnose in patients who are antinuclear antibody (ANA) negative and lack typical clinical manifestations. For such patient who presented ANA‐negative severe lupus‐like manifestations, the diagnosis and treatment are a huge challenge. Histological findings may provide clues to diagnosis.

Systemic lupus erythematosus (SLE) is a multisystem autoimmune disease characterized by formation of autoantibodies to nuclear and cytoplasmic antigens. It was reported that a small subset of patients had typical clinical features of SLE with consistently negative antinuclear antibody (ANA), but such disease is usually mild and rarely involves multisystem. At present, there are no reports about severe lupus with ANA continued negative. Our report describes a 34‐year‐old Chinese woman who presented renal failure, multiple serous cavity effusion, and epilepsy, without malar rash, photosensitivity, lymphopenia, and arthritis. Further renal biopsy pathology revealed lupus‐like nephritis. Autoantibodies, including ANA, antibodies against Smith and against double stranded DNA, were negative. Such a ANA negative and lack of typical clinical symptoms of SLE patient, but with severe lupus‐like manifestations, whether it was lupus or not is worth discussing.
Dihydroguaiazulenide Complexes and Catalysts of Group 8–12 Transition Metals: Ligands from Renewable Feedstock Replace, even Outmatch Petrochemical Based Cyclopentadienyl Chemistry
Authors: Vollgraff Tobias , Doppiu Angelino , Sundermeyer Jörg
Published: November 2023

We present an in‐depth study of the sterically demanding Cp‐synthon (8‐H‐GuaH)Li isolated from natural product guaiazulene (Gua) as a ligand transfer reagent towards late transition metal complex precursors. The synthesis and full characterization of selected, essentially unexplored homo‐ and heteroleptic 8‐H‐guaiazulenide complexes of iron, ruthenium, cobalt, rhodium, platinum, copper and zinc are discussed in detail. In order to demonstrate their potential in catalytic applications, [(GuaH)PtMe3] was selected. The latter proved an even higher catalytic activity in light induced olefin hydrosilylation at catalyst loads as low as 5 ppm than classical [CpPtMe3] in a typical test reaction of silicone elastomer fabrication. Our results demonstrate that traditional petrochemical based Cp metal chemistry and catalysis can be replaced, sometimes even outmatched by superior catalysts based on cheap building blocks from renewable feedstock.
Impact of Polymer Matrix on Polymer Mechanochromism from Excited State Intramolecular Proton Transfer†
Authors: Wu Yu , Cheng Xin , Hu Huan , Hu Shui , Ma Zhimin , Ma Zhiyong
Published: November 2023

Comprehensive Summary

Mechanochromic polymers based on non‐covalent changes have attracted much attention recently. Herein, we report the impact of inter/intramolecular hydrogen bonds on polymer mechanochromism from the excited state intramolecular proton transfer (ESIPT) process. PhMz‐NH2‐OH and PhMz=2A are designed and obtained by simple and high‐yield synthesis, and are connected into polyurethane and poly(methyl acrylate‐co‐2‐ethylhexyl acrylate), respectively. In the initial state, the PhMz‐NH2‐OH@PU sample shows blue fluorescence from the excited enol form (E*) excitons, owing to intermolecular hydrogen bonds that interrupt the ESIPT reactions but the PhMz=2A@PMA‐2‐EA sample expresses cyan fluorescence belonging to the excited keto form (K*) emission, implying that the intramolecular hydrogen bonds matter. Furthermore, under stretching, external force can tune the emission of the PhMz=2A@PMA‐2‐EA sample from K* to E* state. Though external force can putatively still promote a bond rotation, ESIPT reactions remain equivalently interrupted in both the relaxed and stressed states in a hydrogen‐bond donating environment. DFT calculation confirms the force‐induced increase in dihedral angle for the transition of ESIPT‐on/off. Thus, PhMz‐NH2‐OH@PU and PhMz=2A@PMA‐2‐EA showed disparate initial ESIPT states and further different responses/sensitivity to force. This study reports a novel and efficient strategy for enriching mechanochromic investigation and extending the applications of ESIPT reactions.
DMoiSDN: A defensive mechanism of object integrity for SDN
Authors: Alsalamh Nora A. , Al‐Mutairi AbdulRahman , Humayed Abdulmalik A. , Alenazi Mohammed J. F.
Published: November 2023

Software‐defined network (SDN) technology is widely used for computer networks, especially in enterprise data centers and virtualized networking. However, SDN networks encounter severe challenges to security. One such challenge comes from third‐party applications that contain malicious logic and security vulnerabilities, resulting in controller integrity attacks. In this paper, we propose a defensive mechanism of object integrity for SDN (DMoiSDN) to mitigate the issue known as Cross‐App Poisoning (CAP). Our results contribute to increasing the integrity level of the controller's resources by conducting a potential risk analysis, which showed a decrease of 57% in the risk factor for potential attacks. We further examined the results of comparing DMoiSDN's performance with related work that uses information flow control (IFC) policies. The best results among the three conducted scenarios were as follows: we found that decreased latency in our system ranged from 12% to 90%, with an average of 59%, when encountering an increase in requests. It ranged from 78% to 49%, with an average of 63%, when receiving a variable number of total permissions for each application. DMoiSDN is expected to show a perceptible but reasonable latency and, to some extent, be able to avoid a critical impact on performance.
Population Dose–Response‐Time Analysis of Itch Reduction and Patient‐Reported Tolerability Supports Phase III Dose Selection for Linerixibat
Authors: Carreño Fernando , Karatza Eleni , Mehta Rashmi , Collins Jon , Austin Daren , Swift Brandon
Published: November 2023

Increase in serum bile acids (BAs) in patients with primary biliary cholangitis (PBC) may play a causal role in cholestatic pruritus (itch). Linerixibat is a selective small molecule inhibitor of the ileal bile acid transporter, which blocks re‐absorption of BAs in the gastrointestinal tract thereby lowering BAs in the systemic circulation and reducing itch. One consequence is excess BAs in the colon, leading to diarrhea and abdominal pain. GLIMMER (NCT02966834) was a placebo‐controlled phase IIb dose‐ranging trial of linerixibat once (q.d.) or twice daily (b.i.d.) in adults with moderate to severe pruritus and PBC. To determine the optimal dose for maximum itch reduction while minimizing diarrhea, a kinetic‐pharmacodynamic (k‐PD) model was developed using data from GLIMMER. The PD end point modeled was worst daily itch, derived from itch score reported by patients b.i.d. A proportional odds model was developed post hoc to indicate the probability of diarrhea occurrence, a patient‐reported outcome (GI‐5) recorded weekly. The final k‐PD model successfully described the effects of linerixibat and placebo on itch. Model simulations were consistent with the observed dose‐dependent increase in the average number of itch responders (patients with a ≥ 2‐point improvement in itch). This was paralleled by a dose‐dependent increase in the probability of higher diarrhea frequency scores. The b.i.d. dosing regimens led to a modest increase in the number of itch responders as compared with q.d. dosing. This quantitative framework highlights the trade‐off between benefit and tolerability and supported the selection of 40 mg b.i.d. in the phase III GLISTEN trial (NCT04950127).
Imino‐BODIPY‐Based, Highly Sensitive, Fluorescent Dosimeter for Low‐Dose Gamma Radiation**
Authors: Choudhary Manoj K. , Gorai Sudip , Patro Birija S. , Mula Soumyaditya
Published: November 2023

A fluorescent “off‐on” gamma (γ) dosimeter based on an imino‐BODIPY dye is developed. The dosimeter is highly sensitive with the lowest limit of detection (LOD, 0.001 Gy) reported so far for gamma dosimeters based on any analytical method. The dosimeter also shows colorimetric changes under γ‐exposure, which is useful for quick detection of the γ‐doses. A detailed mechanistic study was done to explain these colorimetric and fluorometric changes. Thus, the dosimeter will be useful for measuring accurate gamma‐doses in medical applications due to its high sensitivity. Interestingly, the dynamic range of the dosimeter can be tuned by changing the dye concentration. The dosimeter with 57.0 μM dye is capable of colorimetric and fluorometric measurement of 25 Gy γ‐dose, which is useful for quick and accurate measurement of absorbed γ‐doses during blood irradiation.
Impact of prior coronavirus disease 2019 infection in females on assisted reproductive outcomes: A systematic review with meta‐analysis
Authors: Liu Yiqi , Chen Shen , Chen Mengyi , Xing Chutian , Su Danjie , Fan Lu , Xu Dingfei , Tian Lifeng , Xia Leizhen , Zhang Ke , Wu Qiongfang , Fang Zheng , Huang Jialyu
Published: November 2023

Objectives

To investigate the relationship between prior coronavirus disease 2019 (COVID‐19) infection in females and subsequent treatment outcomes of assisted reproductive technology (ART).

Methods

A systematic literature review was carried out up to 16 December 2022, in PubMed, Web of Science, EMBASE, and Cochrane Library. Random‐effect models were adopted to estimate the pooled effects as mean differences (MDs) or odds ratios (ORs). I2 statistic and Egger's test were applied to assess heterogeneity and publication bias, respectively.

Results

After screening 1480 records, 15 cohort studies totalling 1905 cycles were included in this meta‐analysis. In a comparison of previously COVID‐19‐infected versus uninfected women, no significant differences were observed in the primary outcomes of the retrieved oocytes number (MD = 0.06; 95% confidence interval [CI]: ‐0.75–0.88; I2 = 0) and clinical pregnancy rate (OR = 0.96; 95% CI: 0.74–1.24; I2 = 0). Pooled analyses of other predefined outcomes, which encompassed four cycle characteristics, six laboratory indicators and four pregnancy results, also showed no adverse effects of prior COVID‐19 infection. Most outcomes remained consistent after further sensitivity and subgroup analyses, and no significant publication bias was observed.

Conclusions

Our work provides the first systematic evidence that COVID‐19 infection history in females may have no measurable detrimental impact on the subsequent ART cycle. More data are needed to assess the live birth outcome and the optimal time interval from infection to assisted reproduction.
Temperature variation generates interspecific synchrony but spatial asynchrony in survival for freshwater fish communities
Authors: Pregler Kasey C. , Lu Xinyi , Valentine George P. , Kim Seoghyun , Kanno Yoichiro
Published: November 2023

Identifying environmental drivers of demographic variation is key to predicting community‐level impacts in response to global change. Climate conditions can synchronize population trends and can occur both spatially for populations of the same species, and across multiple species within the same local community. The aim of this study was to investigate patterns of temporal variation in survival for freshwater fish communities in two geographically close but isolated sites and to understand the amount of variation accounted for by abiotic covariates including metrics of water temperature and stream flow. Using mark‐recapture data, we estimated bi‐monthly apparent survival in a Bayesian Cormack‐Jolly‐Seber framework. The model included random effects to quantify temporal variance to understand species synchrony with the rest of the fish community and between sites. Study species included bluehead chub (Nocomis leptocephalus), creek chub (Semotilus atromaculatus), and striped jumprock (Moxostoma rupiscartes) in the southeastern USA. Results showed that survival varied over time and periods of low survival were associated with higher mean water temperature. However, temporal patterns of survival differed among species and between sites, where survival was synchronous among species within a site but asynchronous between sites for the same species despite their spatial proximity. Study streams differed in summer thermal regimes, which resulted in contrasting summer survival patterns, suggesting sensitivity of these fishes to warming. We found that interspecific synchrony was greater than spatial synchrony, where regional drivers such as temperature may interact with local habitat leading to differences in survival patterns at fine spatial scales. Finally, these findings show that changes in the timing and magnitude of environmental conditions can be critical in limiting vital rates and that some populations may be more resilient to climate variation than others.
Global distribution, climatic preferences and photosynthesis‐related traits of C4 eudicots and how they differ from those of C4 grasses
Authors: Berasategui Jessica A. , Žerdoner Čalasan Anže , Zizka Alexander , Kadereit Gudrun
Published: November 2023

C₄ is one of three known photosynthetic processes of carbon fixation in flowering plants. It evolved independently more than 61 times in multiple angiosperm lineages and consists of a series of anatomical and biochemical modifications to the ancestral C3 pathway increasing plant productivity under warm and light‐rich conditions. The C4 lineages of eudicots belong to seven orders and 15 families, are phylogenetically less constrained than those of monocots and entail an enormous structural and ecological diversity. Eudicot C4 lineages likely evolved the C4 syndrome along different evolutionary paths. Therefore, a better understanding of this diversity is key to understanding the evolution of this complex trait as a whole. By compiling 1207 recognised C4 eudicots species described in the literature and presenting trait data among these species, we identify global centres of species richness and of high phylogenetic diversity. Furthermore, we discuss climatic preferences in the context of plant functional traits. We identify two hotspots of C4 eudicot diversity: arid regions of Mexico/Southern United States and Australia, which show a similarly high number of different C4 eudicot genera but differ in the number of C4 lineages that evolved in situ. Further eudicot C4 hotspots with many different families and genera are in South Africa, West Africa, Patagonia, Central Asia and the Mediterranean. In general, C4 eudicots are diverse in deserts and xeric shrublands, tropical and subtropical grasslands, savannas and shrublands. We found C4 eudicots to occur in areas with less annual precipitation than C4 grasses which can be explained by frequently associated adaptations to drought stress such as among others succulence and salt tolerance. The data indicate that C4 eudicot lineages utilising the NAD‐ME decarboxylating enzyme grow in drier areas than those using the NADP‐ME decarboxylating enzyme indicating biochemical restrictions of the later system in higher temperatures. We conclude that in most eudicot lineages, C4 evolved in ancestrally already drought‐adapted clades and enabled these to further spread in these habitats and colonise even drier areas.
Genetic signatures of lineage fusion closely resemble population decline
Authors: Garrick Ryan C.
Published: November 2023

Accurate interpretation of the genetic signatures of past demographic events is crucial for reconstructing evolutionary history. Lineage fusion (complete merging, resulting in a single panmictic population) is a special case of secondary contact that is seldom considered. Here, the circumstances under which lineage fusion can be distinguished from population size constancy, growth, bottleneck, and decline were investigated. Multi‐locus haplotype data were simulated under models of lineage fusion with different divergence versus sampling lag times (D:L ratios). These pseudo‐observed datasets also differed in their allocation of a fixed amount of sequencing resources (number of sampled alleles, haplotype length, number of loci). Distinguishability of lineage fusion versus each of 10 untrue non‐fusion scenarios was quantified based on six summary statistics (neutrality tests). Some datasets were also analyzed using extended Bayesian skyline plots. Results showed that signatures of lineage fusion very closely resemble those of decline—high distinguishability was generally limited to the most favorable scenario (D:L = 9), using the most sensitive summary statistics (FS and ZnS), coupled with the optimal sequencing resource allocation (maximizing number of loci). Also, extended Bayesian skyline plots often erroneously inferred population decline. Awareness of the potential for lineage fusion to carry the hallmarks of population decline is critical.
Oxidative Synthesis of α‐Nitroketones from α‐Substituted Malononitrile and Nitromethane Using Molecular Oxygen without Condensation Reagents
Authors: Hayashi Yujiro , Cocco Emanuele , Odaira Hinata , Matoba Hiroaki , Mori Naoki
Published: November 2023

We developed an oxidative synthetic method for α‐nitroketones from α‐substituted malononitriles and nitromethane under molecular oxygen. Only base and molecular oxygen are necessary without condensation reagents; this is an environmentally benign synthesis.
Resveratrol prevents age‐related heart impairment through inhibiting the Notch/NF‐κB pathway
Authors: Wang Le‐Feng , Li Wen‐Juan , Zhang Xian‐Yi , Zhang Yi‐Chi , Chen Guang‐Feng , Zhou Xing‐Yu , Xv Dong‐Mei , Wu Qiong
Published: November 2023

Resveratrol (RSV) is a natural polyphenol compound found in various plants that has been shown to have potential benefits for preventing aging and supporting cardiovascular health. However, the specific signal pathway by which RSV protects the aging heart is not yet well understood. This study aimed to explore the protective effects of RSV against age‐related heart injury and investigate the underlying mechanisms using a D‐galactose‐induced aging model. The results of the study indicated that RSV provided protection against age‐related heart impairment in mice. This was evidenced by the reduction of cardiac histopathological changes as well as the attenuation of apoptosis. RSV‐induced cardioprotection was linked to a significant increase in antioxidant activity and mitochondrial transmembrane potential, as well as a reduction in oxidative damage. Additionally, RSV inhibited the production of pro‐inflammatory cytokines such as interleukin‐1β (IL‐1β) and tumor necrosis factor‐α (TNF‐α). Furthermore, the expression of toll‐like receptor 4 (TLR4), nuclear factor kappa‐B p65 (NF‐κB p65), and notch 1 protein were inhibited by RSV, indicating that inhibiting the Notch/NF‐κB pathway played a critical role in RSV‐triggered heart protection in aging mice. Moreover, further data on intestinal function demonstrated that RSV significantly increased short‐chain fatty acids (SCFAs) in intestinal contents and reduced the pH value in the feces of aging mice. RSV alleviated aging‐induced cardiac dysfunction through the suppression of oxidative stress and inflammation via the Notch/NF‐κB pathway in heart tissue. Furthermore, this therapeutic effect was found to be associated with its protective roles in the intestine.