bluuebunny/crossref_metadata_2025 huggingface dataset:
PI(3,4,5)P3 allosteric regulation of repressor activator protein 1 controls antigenic variation in trypanosomes
Authors: Touray Abdoulie O. , Rajesh Rishi , Isebe Tony , Sternlieb Tamara , Loock Mira , Kutova Oksana , Cestari Igor
Published: August 2023

African trypanosomes evade host immune clearance by antigenic variation, causing persistent infections in humans and animals. These parasites express a homogeneous surface coat of variant surface glycoproteins (VSGs). They transcribe one out of hundreds of VSG genes at a time from telomeric expression sites (ESs) and periodically change the VSG expressed by transcriptional switching or recombination. The mechanisms underlying the control of VSG switching and its developmental silencing remain elusive. We report that telomeric ES activation and silencing entail an on/off genetic switch controlled by a nuclear phosphoinositide signaling system. This system includes a nuclear phosphatidylinositol 5-phosphatase (PIP5Pase), its substrate PI(3,4,5)P3, and the repressor-activator protein 1 (RAP1). RAP1 binds to ES sequences flanking VSG genes via its DNA binding domains and represses VSG transcription. In contrast, PI(3,4,5)P3 binds to the N-terminus of RAP1 and controls its DNA binding activity. Transient inactivation of PIP5Pase results in the accumulation of nuclear PI(3,4,5)P3, which binds RAP1 and displaces it from ESs, activating transcription of silent ESs and VSG switching. The system is also required for the developmental silencing of VSG genes. The data provides a mechanism controlling reversible telomere silencing essential for the periodic switching in VSG expression and its developmental regulation.
An engineered biosensor enables dynamic aspartate measurements in living cells
Authors: Davidsen Kristian , Marvin Jonathan S , Aggarwal Abhi , Brown Timothy A , Sullivan Lucas B
Published: August 2023

Intracellular levels of the amino acid aspartate are responsive to changes in metabolism in mammalian cells and can correspondingly alter cell function, highlighting the need for robust tools to measure aspartate abundance. However, comprehensive understanding of aspartate metabolism has been limited by the throughput, cost, and static nature of the mass spectrometry based measurements that are typically employed to measure aspartate levels. To address these issues, we have developed a GFP-based sensor of aspartate (jAspSnFR3), where the fluorescence intensity corresponds to aspartate concentration. As a purified protein, the sensor has a 20-fold increase in fluorescence upon aspartate saturation, with dose dependent fluorescence changes covering a physiologically relevant aspartate concentration range and no significant off target binding. Expressed in mammalian cell lines, sensor intensity correlated with aspartate levels measured by mass spectrometry and could resolve temporal changes in intracellular aspartate from genetic, pharmacological, and nutritional manipulations. These data demonstrate the utility of jAspSnFR3 and highlight the opportunities it provides for temporally resolved and high throughput applications of variables that affect aspartate levels.
Frameworking vocational teachers’ digital competences
Authors: Lahn Leif Christian , Berntsen Svanhild Kristine
Published: August 2023

Two decades of international research on digital competence of teachers have provided a number of frameworks for empirical studies and curriculum development. However, research publications addressing the needed digital competence of vocational (VET-) teachers are scarce. In this article we ask to what extent leading conceptual frameworks on digital competence are fruitful templates for studying such competences in the case of VET-teachers’ professional development, and what could be alternative conceptual models that fit this professional category. A synthesis is made of relevant literature based on a theoretical platform in vocational didactics and digitalization that highlights the diversity of international VET-systems and the connectivity between work and school. We adopt an integrative literature research approach that combines systematic procedures and supplementary searches in an iterative way.

Our descriptive analysis of the literature indicated that the international research on VET-teachers digital competence had in general a narrow focus on technical skills with a lack of perspective on key issues about their digital competences such as connectivity school / work, subject-specificity, and adaptive pedagogy. The articles tended to leave out contextual issues, for example the changing professional work of vocational teachers and background information about the national VET-systems. However, part of the literature pointed to the need for more “grounded” research starting from case-studies and qualitative data / mixed-methods research. Our synthesis of the literature in light of our theoretical framing identified four main topics for further research on VET-teachers’ digital competence that were incorporated in a working model or a “frameworking” that needs to be further developed in order to provide a rich and validated basis for constructing professional programs.
Aripiprazole Induced Hypersexuality in A 42-Year-Old Woman with Bipolar Disorder: A Rare Case Report
Authors: Olatunde Hafiz , Basiru Tajudeen , Anombem Odiaka Mark , Busari Adeniyi Kayode , Anugwom Gibson , Ochije Sochima , Aikoye Salisu
Published: August 2023

Background: Aripiprazole use is associated with a very rare side effect of hypersexuality, which was experienced by the patient described in this case study. Hypersexuality can be a very distressing symptom and may also hinder medication compliance.

Case Presentation: A 42-year-old woman with bipolar II disorder developed hypersexuality three weeks after starting aripiprazole, which was used in the treatment of her bipolar disorder.

Discussion: Aripiprazole works by reducing dopaminergic neurotransmission in the mesolimbic pathway. It is believed that due to aripiprazole’s agonistic dopaminergic action in the mesolimbic circuit, it can increase sexual desire.

Conclusion: This case report emphasizes the importance of closely monitoring patients taking aripiprazole for hypersexuality and adds to the existing body of knowledge of aripiprazole-induced hypersexuality.
Evaluation of Serum Prolactin and Testosterone in Premature Ejaculation Patients
Authors: Eid Ahmed Hassan Abdelkader , Elwan Nagwa Mohammad , Hazzaa Sahar Mohey Eldeen , Salam Shady Fikry Abdel
Published: August 2023

Background Premature ejaculation is a frequently encountered sexual dysfunction in men. It significantly impairs quality of life of the affected male and his partner. This study investigated the role of hormonal factors (prolactin and testosterone) in patients with premature ejaculation.

Objectives: evaluating the contribution of prolactin and testosterone in the pathogenesis of premature ejaculation.

Methods: A group of 26 patients suffering from premature ejaculation;15 of them presented with primary type, and 11 of them complained of secondary type. Another group of 10 subjects served as a control group. All the individuals were subjected to clinical evaluation, and venous blood samples for laboratory investigation of serum prolactin and total testosterone.

Results: Comparing the serum prolactin levels between all groups showed no significant statistical differences (p:>0.05). While the levels of total serum testosterone were significantly lower in the primary premature ejaculation patients than in the control group and were more lower in the secondary premature ejaculation patients than both the control and primary type patients (p:<0.05).

Conclusion: It is recommended to routinely investigate testosterone serum levels in secondary premature ejaculation patients, especially that is thought to be a high-risk factor in secondary type.
Science-Based Causation Analysis: Meningioma Example
Authors: Barth Robert J. , Brigham Christopher R.
Published: August 2023

A rigorous scientific approach to causation analysis is essential. This analysis must be rooted in both reliable case facts and trustworthy science. A question about assessing the causation of meningioma following mild head trauma is used as an example to highlight the six-step standard method for causation analysis to validate a causation claim. This article uses causation analysis to examine head trauma as a possible cause of a benign meningioma becoming malignant.
Considerations for Determining Whether Drug Addiction Is a Disability
Authors: Hirsch Joseph A. , Mandel Steven , Hegmann Kurt T. , Stratyner Alexandra G. , Gitlow Stuart , Talmage James B. , Brigham Christopher R.
Published: August 2023

There is an epidemic of drug overdose–related fatalities. Recent data indicate that the age-adjusted death rate from overdoses nearly quintupled over a 20-year period (2001-2021) to 32.4 per 100,000. More than 70% of these fatalities were caused by opioid overdose, especially the synthetic drug, fentanyl. Despite an increase in substance abuse and dependency treatment, mortality and morbidity associated with opioid, cocaine, psychostimulant, benzodiazepine, alcohol, and tobacco use disorders continue to rise. To better understand the factors contributing to this crisis, the multifaceted phenomenon of drug addiction is explored. The controversial chronic, relapsing “disease of the brain” model, which emphasizes the role of the neurotransmitter dopamine, the ventral tegmental area, and the nucleus accumbens, is critically considered. In addition, more expansive neurobiological models that include a host of other neurotransmitters, brain regions, and cognitive processes, as well as classical and operant conditioning and social learning theory to help better understand compulsive drug taking, tolerance, risk-taking, and relapse, were examined. For this, the roles of genetics and epigenetics vs individual agency in drug addiction were considered. The economic and occupational consequences borne both individually and societally are enormous. Ultimately, whether the presence of drug addiction satisfies the criteria for a disability remains a conundrum, especially from the perspectives of financial support (eg, Social Security, private insurance companies) vs regulation (eg, licensing agencies).
Intravenous tirofiban following successful reperfusion in intracranial large artery atherosclerotic stroke: A secondary analysis of a randomized clinical trial
Authors: Huang Jiacheng , Kong Weilin , Liu Chang , Song Jiaxing , Yang Jie , Yue Chengsong , Li Linyu , Hu Jinrong , Tian Yan , Peng Zhouzhou , Guo Changwei , Yang Dahong , Liu Xiang , Miao Jian , Zhang Xiao , Li Fengli , Saver Jeffrey L. , Zi Wenjie
Published: August 2023

Objective

This study aimed to investigate whether treatment with adjunct intravenous tirofiban is associated with improved outcomes following successful reperfusion in patients with intracranial atherosclerotic stroke.

Methods

Patients with intracranial large artery atherosclerotic (LAA) stroke and an expanded Treatment in Cerebral Ischemia angiographic score of 2b50 to 3 from the Effect of Intravenous Tirofiban versus Placebo Before Endovascular Thrombectomy on Functional Outcomes in Large Vessel Occlusion Stroke (RESCUE BT) trial were included. The primary outcome was the difference in proportion of independent functional outcome (modified Rankin score of 0–2 at 90 days). Safety outcomes included the rates of symptomatic intracranial hemorrhage (sICH) and 90‐day mortality.

Results

Among the 382 patients with intracranial LAA stroke and successful reperfusion, 175 patients (45.8%) were treated with intravenous tirofiban and 207 (54.2%) with placebo. The proportion of patients with independent functional outcome at 90 days was 54.3% (95 out of 175) with tirofiban and 44.0% (91 out of 207) with placebo (adjusted odds ratio [aOR], 1.58; 95% CI, 1.02–2.44; p = 0.04). Intravenous tirofiban was not significantly associated with an increased risk of sICH (12/175 [6.9%] vs. 11/207 [5.3%]; aOR, 1.41; 95% CI, 0.59–3.34; p = 0.44) or 90‐day mortality (21/175 [12.0%] vs. 34/207 [16.4%]; aOR, 0.71; 95% CI, 0.38–1.31; p = 0.27).

Interpretation

Among patients with acute intracranial LAA stroke and successful reperfusion following endovascular thrombectomy, adjunct intravenous tirofiban was associated with a higher rate of independent functional outcome, without higher rates of sICH or mortality. Confirmatory randomized trials in these patients are desirable.
Tectonics of the Familiar: The Transposed Landscapes of Zoe Zenghelis
Authors: Khosravi Hamed
Published: August 2023

As a founder member of the now international practice OMA (Office for Metropolitan Architecture), Zoe Zenghelis was responsible for some of the group's early iconic representations of its buildings. In recent times she has practised as a lone painter creating a plethora of work that is at once abstractly Constructivist yet gorgeously architectural as she mixes form and colour. Architect, teacher and writer Hamed Khosravi describes her artistic trajectory and influences.
Liquid Metal Electrodynamic Accumulation Microfluidics System for DNA Memory and Liquid Biopsy
Authors: Jeong Yujin , Noh Seunghwan , Yu Minsang , Chang Sung‐pil , Eun Hyuksoo , Kim Jinchul , Song Youngjun
Published: August 2023

This study presents a liquid metal electrodynamic accumulation microfluidic (LEAM) device that effectively controls DNA dynamics using liquid metal (LM) electrodes and an applied electric field. The characteristics of LM in LEAM include electrochemical attack, and LM properties and behavior at high voltages. The findings demonstrate the ability of the LEAM system to control DNA dynamics and thermodynamics. Short‐sequence single stranded DNA (ssDNA) hybridization and displacement are performed using an exchange buffer solution. By scaling up the LEAM system for a droplet‐based approach, discrete manipulation of DNA samples is achieved. A three‐bit molecular ssDNA memory system using a molecular beacon system is demonstrated, and its application is extended as a diagnostic tool for detecting gene molecules such as micro‐RNA. This study highlights the potential of the LEAM system for use in various biomedical and biotechnological applications, owing to its effective handling of biomolecules.
Functionalized Carbon Honeycomb Membranes for Reverse Osmosis Water Desalination
Authors: Voronin Aleksandr S. , Ho Duc Tam , Schwingenschlögl Udo
Published: August 2023

Reverse osmosis desalination is a common technique to obtain fresh water from saltwater. Conventional membranes suffer from a trade‐off between salt rejection and water permeability, raising a need for developing new classes of membranes. C‐based membranes with porous graphene and carbon nanotubes offer high salt rejection, water permeability, and fouling resistance. However, controlling the pore size of these membranes is challenging.  Therefore, a carbon honeycomb membrane is studied using classical molecular dynamics simulations. It is reported that functionalization with −COO– groups provides 100% salt rejection with around 1000 times higher water permeability than conventional polyamide membranes. Atomic‐level understanding of the effect of the functional groups' location on salt rejection and water permeability is developed.
Facile Hydrothermal Synthesis of Highly Efficient and Durable Ternary PtPdCu Electrocatalysts for the Methanol Oxidation Reaction
Authors: Tian Gui-Xian , Yang Yi , Zhang Rong-Hua , Yan Luo-Yi , Cheng Zheng , Lin Dong-Hai , Zhou Xin-Wen
Published: August 2023

Precious metal Pt‐based electrocatalysts have been widely used in the methanol catalytic oxidation anodes in direct methanol fuel cells. However, decreasing their cost and improving their efficiency and durability have still been challenging. Herein, ternary PtPdCu nanocatalysts are synthesized through a facile one‐step hydrothermal synthesis method. When KI is present with a suitable amount in the synthesis, PtPdCu nanospheres with surface‐embedded CuI clusters (CuI/PtPdCu) are fabricated. However, without KI, the prepared PtPdCu catalysts show a distinct hollow structure (h‐PtPtCu). CuI/PtPdCu displays the highest specific activity with enhancement 4 times higher than commercial Pt/C for the methanol oxidation reaction in an alkaline medium. The superior activity can be attributed to two aspects: 1) the electronic effect originating from the highly alloyed PtPdCu; 2) the synergetic effect resulting from surface inlaid CuI clusters, which can promote the CO intermediate removal. Furthermore, because of the stable Pt–Pd‐rich surface and its special linked hollow structure, the h‐PtPtCu catalyst exhibits good durability with only a 3.6% decay in the specific activity.
Structure and Electronic Properties of SrTiO3–TiO2 Eutectic for Water Splitting Applications
Authors: Guo Yefei , Zeeshan Hafiz Muhammad , Yan Mouhui , Qin Weimin , Yang Wanting , Cao Shixun , Dedkov Yuriy , Voloshina Elena
Published: August 2023

Semiconductors with bandgaps and edges corresponding to the solar energy spectrum are found to be suitable for the water splitting applications using photoelectrochemical reactions. However, many present‐day materials used in these applications do not have high stability and/or high effectiveness over the complete sunlight spectral range. The recently proposed eutectic compounds, which combine two or more semiconducting materials, can overcome many present difficulties and extend the light absorbance spectrum improving the effectiveness of the water splitting cells. Herein, structural and electronic properties studies of the SrTiO3–TiO2 eutectic material, which is a representative example of this family, are presented. It is found that structural properties of this material, particularly the phase separation and formation of the sharp interface between two phases, can be significantly improved up on the thermal annealing, which is very important for their application in the water splitting reactors. The findings present the deep understanding of the interface structure and electronic properties of the SrTiO3–TiO2 eutectic, which can help to improve the functionality of these class of materials in different applications.
Machine Learning‐Accelerated Development of Perovskite Optoelectronics Toward Efficient Energy Harvesting and Conversion
Authors: Chen Baian , Chen Rui , Huang Bolong
Published: August 2023

For next‐generation optoelectronic devices with efficient energy harvesting and conversion, designing advanced perovskite materials with exceptional optoelectrical properties is highly critical. However, the conventional trial‐and‐error approaches usually lead to long research periods, high costs, and low efficiency, which hinder the efficient development of optoelectronic devices for broad applications. The machine learning (ML) technique emerges as a powerful tool for materials designs, which supplies promising solutions to break the current bottlenecks in the developments of perovskite optoelectronics. Herein, the fundamental workflow of ML to interpret the working mechanisms step by step from a general perspective is first demonstrated. Then, the significant contributions of ML in designs and explorations of perovskite optoelectronics regarding novel materials discovery, the underlying mechanisms interpretation, and large‐scale information process strategy are illustrated. Based on current research progress, the potential of ML techniques in cross‐disciplinary directions to achieve the boost of material designs and optimizations toward perovskite materials is pointed out. In the end, the current advances of ML in perovskite optoelectronics are summarized and the future development directions are shown. This perspective supplies important insights into the developments of perovskite materials for the next generation of efficient and stable optoelectronic devices.
Biaxially‐Strained Phthalocyanine at Polyoxometalate@Carbon Nanotube Heterostructure Boosts Oxygen Reduction Catalysis
Authors: Zhu Sheng , Ding Lingtong , Zhang Xuehuan , Wang Kun , Wang Xiao , Yang Feng , Han Gaoyi
Published: August 2023

Iron phthalocyanine (FePc) with unique FeN4 site has attracted increasing interests as a promising non‐precious catalyst. However, the plane symmetric structure endows FePc with undesired catalytic performance toward the oxygen reduction reaction (ORR). Here, we report a novel one‐dimensional heterostructured ORR catalyst by coupling FePc at polyoxometalate‐encapsulated carbon nanotubes (FePc‐{PW12}@NTs) using host‐guest chemistry. The encapsulation of polyoxometalates can induce a local tensile strain of single‐walled NTs to strengthen the interactions with FePc. Both the strain and curvature effects of {PW12}@NT scaffold tune the geometric structure and electronic localization of FeN4 centers to enhance the ORR catalytic performance. As expected, such a heterostructured FePc‐{PW12}@NT electrocatalyst exhibits prominent durability, methanol tolerance, and ORR activity with a high half‐wave potential of 0.90 V and a low Tafel slope of 30.9 mV dec−1 in alkaline medium. Besides, the assembled zinc‐air battery demonstrates an ultrahigh power density of 280 mW cm−2, excellent charge/discharge ability and long‐term stability over 500 h, outperforming that of the commercial Pt/C+IrO2 cathode. This study offers a new strategy to design novel heterostructured catalysts and opens a new avenue to regulate the electrocatalytic performance of phthalocyanine molecules.
Bimetallic Anionic Organic Frameworks with Solid‐State Cation Conduction for Charge Storage Applications
Authors: Zhang Yan , Wang Jiande , Apostol Petru , Rambabu Darsi , Eddine Lakraychi Alae , Guo Xiaolong , Zhang Xiaozhe , Lin Xiaodong , Pal Shubhadeep , Rao Bakuru Vasudeva , Chen Xiaohua , Vlad Alexandru
Published: August 2023

A new phosphonate‐based anionic bimetallic organic framework, with the general formula of A4−Zn−DOBDP (wherein A is Li+ or Na+, and DOBDP6− is the 2,5‐dioxido‐1,4‐benzenediphosphate ligand) is prepared and characterized for energy storage applications. With four alkali cations per formula unit, the A4−Zn−DOBDP MOF is found to be the first example of non‐solvated cation conducting MOF with measured conductivities of 5.4×10−8 S cm−1 and 3.4×10−8 S cm−1 for Li4‐ and Na4‐ phases, indicating phase and composition effects of Li+ and Na+ shuttling through the channels. Three orders of magnitude increase in ionic conductivity is further attained upon solvation with propylene carbonate, placing this system among the best MOF ionic conductors at room temperature. As positive electrode material, Li4−Zn−DOBDP delivers a specific capacity of 140 mAh g−1 at a high average discharge potential of 3.2 V (vs. Li+/Li) with 90 % of capacity retention over 100 cycles. The significance of this research extends from the development of a new family of electroactive phosphonate‐based MOFs with inherent ionic conductivity and reversible cation storage, to providing elementary insights into the development of highly sought yet still evasive MOFs with mixed‐ion and electron conduction for energy storage applications.
Localized Water Infrastructure: Investing in One Water Solutions for Drinking Water Challenges
Authors: Koch Caroline , Kelly Melissa
Published: August 2023

Key Takeaways

Localized water infrastructure (LWI), such as demand management measures, on‐site reuse, and green infrastructure, offers solutions for communities.

Drinking water providers can use LWI to increase sustainability, create resilience to climate change, protect water quality, and equitably secure local water supplies.

LWI provides multiple community benefits, including equity and affordability, and supports environmental, economic, energy, and social improvements.

In the United States, familiar financing approaches, including municipal bonds and state and federal loans, are already available for investing in LWI.
Electrochemical Properties of Single Crystal Electrodes I. The corrosion of single crystals of iron as it is influenced by contact with tin
Authors: Roger Buck W. , Leidheiser Henry
Published: August 2023

Die verschiedenen Netzebenen des Eisengitters verhalten sich wie verschiedene Metalle. Aus der Aufrauhungsgeschwindigkeit der einzelnen Flächenelemente einer elektrolytisch polierten einkristallinen Eisenkugel in acht verschiedenen organischen und anorganischen Säuren ergab sich, daß die höher indizierten, mit (111) kleine Winkel einschließenden Ebenen am schnellsten geätzt wurden, (100) am langsamsten. In luftfreier 0,2 m Zitronensäure korrodierte bei 20°C bzw. beim Siedepunkt (321) 2, 6‐ bzw. 1, 8mal schneller als (100). Die Korrosionsgeschwindigkeit war für (321) auch dann größer als für (100), wenn beide in Kontakt mit polykristallinem Zinn gebracht wurden. Das Verhältnis zwischen Gewichtsverlust des Zinns zu Gewichtsverlust des Einkristalls war für das Paar Fe (100)‐Sn größer als für das Paar Fe (321)‐Sn. Das häufigere Auftreten von Lochfraß auf (100) zeigte, daß diese Ebene mehr zu Lokalelementtätigkeit neigte als (321).
Die Löslichkeit der Silberhalogenide in Sulfitlösungen
Authors: Klein E.
Published: August 2023

Für die Komplexbildung schwerlöslicher Silbersalze in Sulfitlösungen wird eine Gleichung angegeben, die auch die Temperaturabhängigkeit berücksichtigt und folgende Konstanten enthält: die Komplexkonstante, das Löslichkeitsprodukt und die Reaktionswärmen für die reine Wasserlöslichkeit und die Komplex‐bildung.

Die Temperaturabhängigkeit der Löslichkeitsprodukte von AgJ, AgBr, AgCNS, AgCl wird experimentell bestimmt.

Messungen der Komplexkonstanten in Abhängigkeit von der Temperatur an den Systemen AgJ, AgBr, AgCNS, AgCl führen zu einem völlig übereinstimmenden Ergebnis, so daß die Gleichungen zur Berechung der Löslichkeit der Silberhalogenide in Sulfitlösungen mit Temperaturabhängigkeit angegeben werden können.

Der Einfluß, den der pH‐Wert sowie die Komplexbildung der Silberhalogenide mit Halogenionen ausüben können, wird diskutiert.
Analytische Untersuchungen über die Vorgänge bei der elektrolytischen Reduktion wäßriger schwefelsäurehaltiger Chromsäurelösungen
Authors: Frey M. , Knorr C. A.
Published: August 2023

Die für die Verchromung und Darstellung sehr reinen Chroms wichtigen Vorgänge bei der kathodischen Reduktion wäßriger, schwefelsäurehaltiger Chromsäurelösungen wurden erneut untersucht. Wie aus früheren Arbeiten hervorgeht, entsteht bei der Elektrolyse reiner Chromsäurelösungen eine, vermutlich aus Cr(III)‐Chromat bestehende Deckschicht auf der Kathode, die eine Reduktion der Chromsäure weitgehend verhindert, so daß im wesentlichen nur Wasserstoff entwickelt wird. Schon bei Zugabe geringer Mengen von Fremdanionen, wie u. a. Sulfat, erfolgt neben Wasserstoffentwicklung auch Abscheidung von metallischem Chrom und Cr(III). Die als Zusatz in geringer Konzentration in der Chromsäure notwendigen Sulfat‐Ionen werden, wie gefunden wurde, bei Stromdurchgang an der Kathode allmählich in eine im Innern des Elektrolyten analytisch nachweisbare, durch Bariumchloridzusatz bei Zimmertemperatur nicht ausfällbare Komplexverbindung übergeführt.

Die bekannte Fremdanionenwirkung kommt, wie im folgenden gezeigt wird, nur den freien, nicht aber den gebundenen Sulfat‐Ionen zu, so daß eine durch ein Diaphragma von der Anode abgetrennte schwefelsäurehaltige Chromsäurelösung infolge Abnahme des freien Sulfats bei der Elektrolyse allmählich unwirksam wird. Ohne Diaphragma wird die an der Kathode gebildete Sulfatoverbindung an einer Pb‐Anode wieder zerstört, so daß dann die Chromabscheidung zeitlich unbegrenzt stattfinden kann.
Zum Primärprozeß der Photosynthese an Chlorophyllkörnern außerhalb der pflanzlichen Zelle
Authors: Witt H. T. , Moraw R. , Müller A.
Published: August 2023

Bei Anregung der Photosynthese mit Blitzlicht kann man durch empfindliche Messung kurzzeitiger Absorptionsänderungen (0,1%) sehr schnelle Reaktionen während der Photosynthese zwischen 10−5sec und mehreren Sekunden verfolgen. Diese Methode erweitert den Meßbereich der bisherigen Verfahren um 5 Größenordnungen. Damit ist es möglich, den schnell ablaufenden, bisher unzugänglichen Primärprozeß der Photosynthese zu untersuchen.

An der pflanzlichen Zelle wurden im Primärprozeß bisher drei zusammenhängende Reaktionen — eine Photochemische Reaktion F, eine Chemische Reaktion C und eine Chemische Dunkelreaktion D — sowie die Absorptionsbanden daran beteiligter Stoffe bei ∼ 475 mμ und ∼ 515 mμ beobachtet.

An isolierten Chlorophyllkörnern (Chloroplasten) laufen diese Reaktionen außerhalb der pflanzlichen Zelle in vereinfachter Form ab. Außerdem kann man an den Chlorophyllkörnern den zeitlichen Verlauf der Reduktionsreaktion R messen, indem man an Stelle von CO2 Farbstoffe reduzieren läßt. — Bei Verwendung von bestimmten Farbstoffen läßt sich die Chemische Dunkelreaktion D künstlich nahezu um den Faktor 100 beschleunigen.

Mit diesen Eingriffen eröffnet sich die Möglichkeit, den Mechanismus des Primärprozesses genauer zu bestimmen.
Emploi de la thermodynamique et de la cinétique électrochimiques pour l'étude des phénomènes de passivation
Authors: Pourbaix Marcel
Published: August 2023

Auf Grund thermodynamischer Daten werden die Gleichgewichtszustände elektrochemischer Reaktionen an Hand von PH/Potential‐Diagrammen diskutiert. Aus solchen Diagrammen lassen sich die thermodynamischen Bedingungen voraussagen, unter denen ein gegebenes Elektrodensystem Korrosion, Immumtät oder Passivität zeigt. Dies wird an dem System Eisen—Wasser näher erläutert. Durch Überlagerung des pH/Potential‐Diagrammes des Eisens mit denen des Chroms, des Molybdäns, Wolframs, Vanadiums, Technetiums oder des Rheniums läßt sich die Wirkung der oxydierenden Inhibitoren (Chromat, Molybdat, Wolframat, Vanadat, Pertechnetat und Perrhenat) auf die Zersetzung des Eisens unmittelbar deuten. Hinsichtlich der Kinetik elektrochemischer Reaktionen gestatten die Diagramme vorauszusagen, ob Korrosions‐ oder Passivierungsreaktionen energetisch möglich sind oder nicht. Mit Hilfe des von Wagner und Traud angegebenen Prinzips der Überlagerung von Polarisationskurven miteinander gekoppelter Elektrodenreaktionen lassen sich auf diese Weise Aussagen machen über die Richtung und Geschwindigkeit möglicher Elektrodenumsätze, insbesondere über die Korrosion, Passivierung und Aktivierung passivierbarer Metalle.
Anaerobic corrosion of metals in solutions containing various metallic cations inactivation and activation
Authors: Buck W. Roger , Leidheiser Henry
Published: August 2023

Three cases of the inactivation of a metal by small amounts of a foreign metal originally present as a cation in solution are cited: the inactivation of iron by Sn(II) and Pb(II) ions in boiling 0.2 M citric acid; the inactivation of nickel by Cu(II) ions in boiling 2 M HC1; and the inactivation of titanium in boiling 2 M HC1 by the Group VIII metals, rhodium, ruthenium, palladium, iridium, osmium, and platinum. Experiments on the activation of aluminum, copper, iron, nickel, silver, tin, and zinc in boiling acids by the Group VIII metals are also described. The foreign metal is considered to exert its influence on the activity of the corroding metal only after it is reduced to the metallic state at the surface. It is suggested that the corrosion rate which results is controlled by the type of electron transfer which occurs between the two kinds of metal atoms at the solution‐metal interface.
Eine Temperatursprungmethode zur Untersuchung schneller Dissoziations‐reaktionen mit Hilfe eines Mikrowellen‐Impulses
Authors: Ertl G. , Gerischer H.
Published: August 2023

Bei der Störung eines chemischen Gleichgewichts durch eine sprungartige Temperaturerhöhung können durch Beobachtung des zeitlichen Verlaufs der neuen Gleichgewichtseinstellung Aussagen über die Kinetik des Reaktionssystems gewonnen werden. Es wird ein Verfahren beschrieben, in dem zur schnellen Aufheizung die mit der dielektrischen Relaxation verknüpfte Energieabsorption polarer Moleküle benutzt wird. Für Wasser liegt das Absorptionsmaximum bei 1010 Hz (= 3 cm Wellenlänge), einem Frequenzbereich, in dem Energiestrahler mit sehr hoher Leistung zur Verfügung stehen. In einer geeigneten Anordnung kann damit die Temperatur um 0,7°C innerhalb weniger μsec erhöht werden. Zur Erprobung der Methode wurden die Geschwindigkeitskonstanten der Dissoziationsreaktion des Wassers ermittelt.
Dielektrische Relaxationserscheinungen adsorbierter Molekeln im Hochfrequenzgebiet
Authors: Ebert G.
Published: August 2023

Es wird über die dielektrischen Untersuchungen am System γ‐Al2O3/Wasser zwischen 100 kHz und 10 MHz im Temperaturbereich von − 60 °C bis + 100°C berichtet. Die hierbei im ϵ″‐T‐Diagramm festgestellten Hoch‐ und Tieftemperaturmaxima werden mit Hilfe der Eyringschen „chemical rate theory”︁ gedeutet. Neben der Möglichkeit zur Bestimmung von Oberflächen lassen sich auch Adsorptionswärmen auf dielektrischem Wege ermitteln. Im Gegensatz zum üblichen Cole‐Cole‐Diagramm erhält man beim Auftragen von ϵ″ gegen ϵ′ bei verschiedenen Temperaturen (entsprechend verschiedenen Platzwechselfrequenzen der adsorbierten Molekeln) und jeweils konstanter Feldfrequenz Kreisbögen. Diese Tatsache erlaubt die Beschreibung der Temperaturabhängigkeit von ϵ′ und ϵ″ adsorbierter Molekeln mittels bekannter Beziehungen.
Ultraschallabsorptionsmessungen in verdünnten Lösungen von Hochpolymeren
Authors: Cerf R. , Candau S. , Zana R.
Published: August 2023

Es wird ein Verfahren zur Messung der Ultraschallabsorption beschrieben, das erlaubt, in gewissen Bereichen die Messungen mit kontinuierlich veränderlicher Frequenz durchzuführen. Es wurde zwischen 0,8 Mhz und 20 Mhz gearbeitet. In verschiedenen makromolekularen Lösungen konnte beim Überschreiten einer bestimmten Frequenz eine rasche Abnahme der spezifischen Absorption αsp = (α–α0)/α0 beobachtet werden. (α ist der Absorptionskoeffizient der Lösung, α0 der des Lösungsmittels.)

Zur Deutung dieser Erscheinung wird die Annahme gemacht, daß in einer Flüssigkeit die Größen ∂A12∂F|0 und ∂A21∂F|0 von der Frequenz des Feldes abhängen. A12 und A21 sind die Übergangswahrscheinlichkeiten, die in der Theorie der akustischen Relaxation erscheinen. F ist die Feldstärke des akustischen Feldes.
Untersuchung der Auflösung des passiven Eisens in Schwefelsäure mit der rotierenden Scheiben‐Ring‐Elektrode
Authors: Heusler K. E.
Published: August 2023

Die Auflösungsgeschwindigkeit einer passiven Eisenscheibe zu dreiwertigem Eisen, gemessen als Diffusionsgrenzstrom der Eisenionen an der Ringelektrode, steigt mit dem anodischen Strom is am Eisen steil an. Nur ein kleiner, mit is und dem pH‐Wert der Lösung wachsender Teil von is dient zum Aufbau der passivierenden Oxidschicht. In dem Potentialbereich, in dem die stationäre Auflösungsgeschwindigkeit unabhängig vom Potential ist, werden zur Änderung der Schichtdicke 5,5 (±0,9) mAsec/cm2 V gespeichert, entsprechend 29 (±5) Å/V. Nach plötzlicher Erniedrigung des Potentials erreicht die Auflösungsgeschwindigkeit der Passivschicht zu dreiwertigem Eisen einen endlichen Minimalwert.

Der Anstieg des anodischen Stromes is bei relativ unedlen Potentialen beruht allein auf der zunehmenden Auflösungsgeschwindigkeit der Passivschicht zu zweiwertigem Eisen.

Der Austauschstrom für den Durchtritt von Sauerstoffionen an der Phasengrenze zwischen Oxid und Lösung ist unabhängig von Elektrodenpotential und pH‐Wert.

Der aus den Experimenten folgende Mechanismus von Schichtwachstum und Schichtauflösung wird diskutiert.
Aussagen über Ordnungsstrukturen in Polymeren aus kalorimetrischen Untersuchungen
Authors: Gerth Chr. , Göritz D. , Müller F. H.
Published: August 2023

Kalorimetrische Messungen können in sehr empfindlicher Weise den Nachweis von Ordnungszuständen gestatten. Das gilt vor allem für die Kombination verschiedener Meßmethoden. Im folgenden sollen 2 Fälle herausgestellt werden, in denen sich besonders der Wert kalorimetrischer Messungen zeigt. Anhand von Messungen an Naturkautschuk und Polyisobutylen wird ausgeführt, wie man mit Hilfe von kalorischen Messungen in besonderer Empfindlichkeit auch sehr geringfügige Änderungen des kristallinen Anteils und vor allem die zeitliche Entwicklung der Kristallisation sehr genau verfolgen kann. Das zweite Beispiel ist das isotaktische Polymethylmethacrylat, das sowohl durch Abschrecken röntgenamorph erhalten werden kann als auch durch eine Temper‐Behandlung partiell kristallin. Der Kristallinitätsgrad läßt sich aus Röntgenaufnahmen abschätzen. Wenn man einerseits differential‐thermoanalytische Messungen, andererseits Messungen der Lösungswärme für amorphes und partiell kristallines PMMA vornimmt, so ergibt eine Diskussion, daß die verschiedenen Werte nur dann miteinander verträglich sind, wenn man dem amorphen Material eine beträchtliche Nahordnung zuweist.
Elektrokatalyse an Phosphiden der Eisengruppe und einigen ternären Verbindungen
Authors: Mund K. , Richter G. , Schulte R. , Sturm F. V.
Published: August 2023

In der Gruppe der Phosphide der Eisenmetalle und bei ternären Verbindungen zwischen den Metallen der Eisengruppe einerseits und zwei Metalloiden der Gruppen P, As, Sb und S, Se, Te andererseits finden sich einige Verbindungen, die als Elektrokatalysatoren in der Wasser‐stoffelektrode fungieren können. Zu ihnen gehören das FeP2, das CoP3 und das CoPS. Der Stabilitätsbereich gegen den korrosiven Angriff des sauren Elektrolyten reicht bei 70°C für CoP3 bis +150mV, für CoPS bis +300mV, gemessen gegen die reversible H2‐Elektrode. An glatten Elektroden wurden aus dem kathodischen Ast der Stromspannungskennlinie Austauschstromdichten bestimmt, die bei den Eisen‐ phosphiden, bei CoP3 und NiP3 um 10−5 A/cm2 liegen. Der anodische Ast neigt zur Grenzstromausbildung. Gestützte poröse Wasserstoffanoden aus FeP2 konnten bei 70 °C und 100 mV Polarisation mit 40 mA/cm2, diejenigen aus CoP3 mit 200 mA cm2 belastet werden. In Dauerversuchen über 2000 Stunden war keine Abnahme der katalytischen Aktivität zu beobachten.
Behandlung eines irreversiblen komplizierten Mehrelektronenschrittes als unverzweigte offene Kette
Authors: Schwarzer E. , Hamann C. H. , Heitbaum J.
Published: August 2023

Als unverzweigte offene Kette bezeichnet man ein Reaktionsschema, in welchem die entstehenden Zwischenprodukte im jeweiligen Folgeschritt wieder umgesetzt werden und bei dem für jede Teilreaktion nur ein Reaktionsweg möglich ist. Christiansen hat für ein solches Reaktionsschema die Reaktionsgeschwindigkeit in Abhängigkeit von der Ausgangskonzentration und von den Reaktionswahrscheinlichkeiten der Einzelschritte berechnet, und zwar auch bei Einschluß irreversibler Teilschritte. Bei Übertragung dieser Rechnung auf elektrochemische Reaktionen ist zusätzlich der Einfluß der Belegung der Elektrode mit Zwischenprodukten zu beachten.

Wir haben das Schema der unverzweigten Kette auf die irreversible anodische Oxidation von Ameisensäure an Platin in schwefelsaurer Lösung angewendet. Als Ergebnis erhalten wir, daß der Übergang des ersten Elektrons geschwindigkeitsbestimmend ist. Zur Identifizierung von Zwischenprodukten wird eine massenspektrometrische Methode vorgeschlagen.
Reflexionsoptische Untersuchungen elektrochemisch erzeugter solvatisierter Elektronen in Ammoniak und in Salzschmelzen
Authors: Postl D. , Schindewolf U. , Schmitt W. , Wiinschel P.
Published: August 2023

Durch Impulselektrolyse in Verbindung mit reflexionsoptischen Messungen wird gezeigt, daß solvatisierte Elektronen als Primerteilchen bei der Elektrolyse von Lösungen einfacher Salze in flüssigem Ammoniak und von Salzschmelzen gebildet werden. Reduzierbare Substanzen werden an der Kathode direkt, d. h. ohne intermediäre Bildung solvatisierter Elektronen reduziert.

Die Spektren der solvatisierten Elektronen in der Salzschmelze werden mit zunehmender Größe der Kationen und mit steigender Temperatur in den längerwelligen Spektralbereich verschoben. Die Interpretation dieser Ergebnisse erfolgt in Anlehnung an die Theorie der solvatisierten Elektronen in polaren Lösungsmitteln und der F‐Zentren in festen Ionenkristallen.
Parenting children with ADHD when the parent also has ADHD
Authors: Walters Anne S.
Published: August 2023

In the field of behavioral health, as with any other field, some topics seem to capture the attention of both the layperson and the expert for a period of time — a recent example has been the effects of social media on children.
NPHP1‐Related ciliopathies: A new case and major review of the ophthalmic manifestations of 147 reported cases
Authors: Reddy Shivania , Simmers Russell , Shah Arth , Couser Natario
Published: August 2023

Key Clinical Message

Our case report and review contribute to the understanding of ocular manifestations in NPHP1 ciliopathies by reinforcing the relationship between pathogenic genetic variants and a wide array of ophthalmic abnormalities.
Molecular pathology and clinical treatment of independent HPV primary serous carcinoma of the uterine cervix (USCC): A case report
Authors: Niu Lina , Ruan Fangying , Yang Qisheng , Xia Chaoran , Xu Tao , Dong Fei , Zhang Lizhen , Guo Sheng , Lv Weiqin , Wang Junxia , Shang Yun
Published: August 2023

On October 23, 2020, a 69‐year‐old Chinese female patient was admitted to Yuncheng Hospital due to a history of postmenopausal bleeding and lower abdominal pain for 5 months. The HPV test and pathology results indicated the presence of independent HPV in primary serous carcinoma of the uterine cervix. The genetic testing identified variants of uncertain significance (PAX8 p.Tyr 410 Ter and TP53 p.Asn 247 Ile), microsatellite instability stable (MSI‐S), tumor mutational burden (TMB) 7.33Muts/Mb, and an elevated tumor neoantigen burden. Before undergoing radical hysterectomy treatment, the patient exhibited a positive response to three cycles of intravenous docetaxel (100 mg/3 h) and carboplatin (450 mg/1 h). Following the surgery, she received an additional three cycles of docetaxel (100 mg/3 h) and carboplatin (500 mg/1 h), accompanied by 25 cycles of radiation therapy (DT 46Gy/2Gy/23f). Concurrently, cisplatin (450 mg/1 h) was administered. As of now, the patient has achieved 20 months of disease‐free survival.
Reversible Binding of Hydrogen and Styrene Coordination on a Manganese Phosphenium Complex
Authors: Papendick Marius , Gudat Dietrich
Published: August 2023

The reactions of two complexes [(RNHP)Mn(CO)4] (RNHP=N‐arylated N‐heterocyclic phosphenium) with H2 at elevated pressure (≈4 bar) were studied by NMR spectroscopy. Irradiation with UV light initialized in one case (5 a, R=Dipp) the unselective formation of (RNHP‐H)MnH(CO)4] (6 a) via cooperative addition of H2 across the Mn=P double bond. In the other case (5 b, R=Mes), addition of H2 was unobservable and the reaction proceeded via decarbonylation to a dimeric species [(RNHP)2Mn2(CO)7] (7 b) that was isolated and identified spectroscopically. Taking into account the outcome of further reaction studies under various conditions in the absence and presence of H2, both transformations can be explained in the context of a common mechanism involving decarbonylation to 7 a,b as the first step, and the different outcome is attributable to the fact that 7 b is unreactive towards both H2 and CO while 7 a is not. DFT studies relate this divergence to deviations in the molecular constitution and stability arising from a different level of steric congestion. Preliminary studies suggest further that 5 a/H2 as well as 6 a enable the photo‐induced hydrogenation of styrene to ethyl benzene, even if the mechanism and possibly catalytic nature of this process remain yet unknown.
Cleavage furrow positioning in dividing Dictyostelium cells
Authors: Okada Akiko , Yumura Shigehiko
Published: August 2023

Accurate placement of the cleavage furrow is crucial for successful cell division. Recent advancements have revealed that diverse mechanisms have evolved across different branches of the phylogenetic tree. Here, we employed Dictyostelium cells to validate previous models. We observed that during metaphase and early anaphase, mitotic spindles exhibited random rotary movements which ceased when the spindle elongated by approximately 7 μm. At this point, astral microtubules reached the polar cell cortex and fixed the spindle axis, causing cells to elongate by extending polar pseudopods and divide along the spindle axis. Therefore, the position of the furrow is determined when the spindle orientation is fixed. The distal ends of astral microtubules stimulate the extension of pseudopods at the polar cortex. One signal for pseudopod extension may be phosphatidylinositol trisphosphate in the cell membrane, but there appears to be another unknown signal. At the onset of polar pseudopod extension, cortical flow began from both poles toward the equator. We suggest that polar stimulation by astral microtubules determines the furrow position, induces polar pseudopod extension and cortical flow, and accumulates the elements necessary for the construction of the contractile ring.
Efficacy of two diode lasers in the removal of calculus from the root surface: An in vitro study
Authors: Marcattili Domenico , Mancini Leonardo , Tarallo Francesco , Casalena Fabio , Pietropaoli Carla , Marchetti Enrico
Published: August 2023

Introduction

Scaling and root planning (SRP) is still the gold standard of nonsurgical periodontal therapy, and it has been accompanied by several supportive therapies in recent years. One of the most studied methods is the diode laser, thanks to its thermal and bactericidal properties. Our trial intended to verify whether it could influence the chemical bond between calculus and the root surface.

Objectives

The aim of the study was to assess the efficacy of the diode laser prior the mechanical removal of calculus in an in vitro application. The reduction in time and the number of strokes required to clean the untreated root surfaces were evaluated as primary outcomes. The pressure was considered as a secondary outcome.

Methods

A total of 75 extracted human teeth with subgingival calculus were assigned equally among three treatment groups (n = 25) according to the size of the occupied areas, which were classified by evaluating the pixel numbers. The groups were assigned to either no pretreatment application (A), Laser Diode Fox III (Sweden & Martina) (B) or Wiser Laser Evolution (Doctor Smile) (C). The weight for instrumentation was calibrated for an After Five curette (Hu‐Friedy, Chicago). A new set of tools was used for each group, and the curettes were sharpened after each use with the Sidekick sharpener (Hu‐Friedy, Chicago).

Results

A Kruskal–Wallis test was used to assess the significance for each considered parameter. The results were statistically significant for each parameter for the two groups where the laser was used compared to the control group.

Conclusions

Despite the limitations of an in vitro study, data showed that the diode laser had an overall positive effect on root debridement, facilitating SRP in terms of stroke count, time, and pressure.