POE-Mediated Tunable Quantum Yield of Carbon Dots-Derived From Agapanthus Africanus (L.) Hoffmann Leaves.

The green synthesis of carbon dots (CDs) from natural sources is a challenging goal. Herein CDs are produced from Agapanthus africanus (L.) Hoffmann leaves by carbonization at 200/300 °C for 2/3 h. Samples are named CZ-X-Y, where Z, X, and Y represent carbonization, temperature, and time, respectively. CZ-200-3, CZ-300-2, and CZ-300-3 CDs have average sizes of 3.7 ± 0.7, 5.3 ± 1.2, and 5.1 ± 1.6 nm, respectively. Their surface, devoid of chlorophyll, contains ─OH, ─C═O, and ─C(═O)OH groups and sylvite. Isolated CZ-300-3 emits at 400 nm (excited at 260 nm) and exhibits an emission quantum yield (QY) value of 2 ± 1%. Embedding in the d-U(600)/d-(900) di-ureasil matrices resulted in transparent films with emission intensity maxima at 420/450 nm (360 nm), and QY values of 7 ± 1/16 ± 2% (400 nm). The enhancement of the QY value of the bare CDs agrees with an efficient passivation provided by the hybrid host. The hydrophilic CZ-300-3 CDs also exerted a marked surface modifying role, changing the surface roughness and the wettability of the hybrid films.

Woodward-Hoffmann or Hoffmann-Woodward? Cycloadditions and the Transformation of Roald Hoffmann from a "Calculator" to an "Explainer".

On May 1, 1965, Roald Hoffmann and R. B. Woodward published their second joint communication, Selection Rules for Concerted Cycloaddition Reactions, in the Journal of the American Chemical Society. Herein is presented a historical analysis of Woodward and Hoffmann's determination of the mechanism of cycloadditions. This analysis is based on thorough analyses with Roald Hoffmann of his 1964 and 1965 laboratory notebooks and his archived documents and on numerous in-person, video, and email interviews. This historical research pinpoints several seminal moments in chemistry and in the professional career of Hoffmann. For example, now documented is the fact that Woodward and Hoffmann had no anticipation that their collaboration would continue after the publication of their first 1965 communication on electrocyclizations. Also pinpointed is the moment in Hoffmann's professional and intellectual trajectories that he became a full-fledged, equal collaborator with Woodward and Hoffmann's transition from a "calculator" to an "explainer."

Hoffmann's sign in cervical spondylotic myelopathy patients: pathological insights from neuroimaging.

OBJECTIVE: Hoffmann's sign testing is a commonly used physical examination in clinical practice for patients with cervical spondylotic myelopathy (CSM). However, the pathophysiological mechanisms underlying its occurrence and development have not been thoroughly investigated. Therefore, the present study aimed to explore whether a positive Hoffmann's sign (PHS) in CSM patients is associated with spinal cord and brain remodeling and to identify potential neuroimaging biomarkers with diagnostic value. METHODS: Seventy-six patients with CSM and 40 sex- and age-matched healthy controls (HCs) underwent multimodal MRI. Based on the results of the Hoffmann's sign examination, patients were divided into two groups: those with a PHS (n = 38) and those with a negative Hoffmann's sign (NHS; n = 38). Quantification of spinal cord and brain structural and functional parameters of the participants was performed using various methods, including functional connectivity analysis, voxel-based morphometry, and atlas-based analysis based on functional MRI and structural MRI data. Furthermore, this study conducted a correlation analysis between neuroimaging metrics and neurological function and utilized a support vector machine (SVM) algorithm for the classification of PHS and NHS. RESULTS: In comparison with the NHS and HC groups, PHS patients exhibited significant reductions in the cross-sectional area and fractional anisotropy (FA) of the lateral corticospinal tract (CST), reticulospinal tract (RST), and fasciculus cuneatus, concomitant with bilateral reductions in the volume of the lateral pallidum. The functional connectivity analysis indicated a reduction in functional connectivity between the left lateral pallidum and the right angular gyrus in the PHS group. The correlation analysis indicated a significant positive association between the CST and RST FA and the volume of the left lateral pallidum in PHS patients. Furthermore, all three variables exhibited a positive correlation with the patients' motor function. Finally, using multimodal neuroimaging metrics in conjunction with the SVM algorithm, PHS and NHS were classified with an accuracy rate of 85.53%. CONCLUSIONS: This research revealed a correlation between structural damage to the pallidum and RST and the presence of Hoffmann's sign as well as the motor function in patients with CSM. Features based on neuroimaging indicators have the potential to serve as biomarkers for assessing the extent of neuronal damage in CSM patients.

Effects of different fabrics on the Hoffmann reflex during local heat exposure.

[Purpose] The effects of multifunctional garments on neuromuscular performance have gained significant research attention in the health sciences. However, the spinal responses to different fabrics have not yet been considered. In the present study, we examined the effects of typical fabrics (cotton and polyester) on the Hoffmann reflex during local heat exposure. [Participants and Methods] Sixteen healthy males aged 20-40 years participated in this study. A heating device comprising a thermal mat, fabric, and a data logger was fabricated. The fabric was affixed to the skin as the contact surface. The temperature of the right posterior lower leg was increased to 39°C followed by 10 min for adaptation at 39-40°C. The H- and M-waves were recorded at each point, including those without heating. An identical trial was conducted seven days later using the alternative fabric. [Results] M-wave amplitude and latency were significantly decreased during heat exposure without fabric. The H-wave latency was prolonged by sustained thermal heat during the session with polyester. Interestingly, the H-wave amplitudes normalized by the maximal M-wave amplitudes decreased with prolonged heat exposure during the session with cotton. However, this index remains unchanged during the sessions using polyester. [Conclusion] During prolonged localized thermal exposure, cotton reduced spinal excitability, whereas polyester preserved spinal excitability.

Effect of repetitive peripheral magnetic stimulation of the common fibular nerve on the soleus muscle Hoffmann reflex.

[Purpose] This study aimed to investigate the effects of repetitive peripheral magnetic stimulation of the common fibular nerve on the modification of neural circuit function as measured through the soleus muscle Hoffmann reflex. [Participants and Methods] Twenty-four healthy adult males were randomly and equally divided into the magnetic stimulation (experimental) and control groups. The Hoffmann reflex of the soleus muscle was analyzed before and after 10 min of repetitive peripheral magnetic stimulation for the experimental group and before and after 10 min of rest for the control group. The averages of the values for the maximum amplitude and latency of the Hoffman reflex across twenty repetitions were recorded and compared. [Results] The Hoffmann reflex amplitude decreased following stimulation in the experimental group, and significant variations were observed between the experimental and control groups. [Conclusion] The change in the Hoffmann reflex amplitude may have been caused by the magnetic stimulation to I-a sensory fibers on the common fibular nerve, suggesting that magnetic stimulation induces reciprocal inhibition of motor neurons through synapses in the spinal cord.

Introduction to "The Woodward-Hoffmann Rules. From May 5, 1964, to November 30, 1964".

An introduction is provided to Publication 11 in the series of articles by the author on the history of the Woodward-Hoffmann (W-H) rules. Now permanently open access (CC-BY) at http://pubs.acs.org/doi/abs/10.1021/acs.joc.5b01792, Paper 11 was published in 2015 in The Journal of Organic Chemistry to celebrate the 50th anniversary of the W-H rules. This paper summarizes the content of Publications 1-10 in the series and provides an idea of the major components of Publication 11.

Why Woodward and Hoffmann? And Why 1965?

Previous publications in this series on the history of the development of the Woodward-Hoffmann rules revealed why Woodward and Hoffmann were prime candidates to solve the pericyclic no-mechanism problem. This publication explains why it was the collaborative team of R. B. Woodward and Roald Hoffmann who did solve this mechanistic problem in a series of five communications in the Journal of the American Chemical Society in 1965. That is, the reasons why Woodward and Hoffmann were the perfect team, and why their individual capabilities, experiences, and qualities provided the perfect synergy are described. In part, this was the right time and the right place for them both, but the synergies were fundamental, intrinsic and idiosyncratic as a collaborative pair. Their orbital symmetry rules provided the mechanism of all concerted pericyclic reactions including electrocyclizations, cycloadditions, and sigmatropic rearrangements. Why it was 1965 and not earlier is also discussed.

Differences in Trapezius Muscle H-Reflex between Asymptomatic Subjects and Symptomatic Shoulder Pain Subjects.

In chronic shoulder pain, adaptations in the nervous system such as in motoneuron excitability, could contribute to impairments in scapular muscles, perpetuation and recurrence of pain and reduced improvements during rehabilitation. The present cross-sectional study aims to compare trapezius neural excitability between symptomatic and asymptomatic subjects. In 12 participants with chronic shoulder pain (symptomatic group) and 12 without shoulder pain (asymptomatic group), the H reflex was evoked in all trapezius muscle parts, through C3/4 nerve stimulation, and the M-wave through accessory nerve stimulation. The current intensity to evoke the maximum H reflex, the latency and the maximum peak-to-peak amplitude of both the H reflex and M-wave, as well as the ratio between these two variables, were calculated. The percentage of responses was considered. Overall, M-waves were elicited in most participants, while the H reflex was elicited only in 58-75% or in 42-58% of the asymptomatic and symptomatic participants, respectively. A comparison between groups revealed that the symptomatic group presented a smaller maximum H reflex as a percentage of M-wave from upper trapezius and longer maximal H reflex latency from the lower trapezius (p < 0.05). Subjects with chronic shoulder pain present changes in trapezius H reflex parameters, highlighting the need to consider trapezius neuromuscular control in these individuals' rehabilitation.

Neuromuscular and gene signaling responses to passive whole-body heat stress in young adults.

This study aimed to investigate whether acute passive heat stress 1) decreases muscle Maximal Voluntary Contraction (MVC); 2) increases peripheral muscle fatigue; 3) increases spinal cord excitability, and 4) increases key skeletal muscle gene signaling pathways in skeletal muscle. Examining the biological and physiological markers underlying passive heat stress will assist us in understanding the potential therapeutic benefits. MVCs, muscle fatigue, spinal cord excitability, and gene signaling were examined after control or whole body heat stress in an environmental chamber (heat; 82 °C, 10% humidity for 30 min). Heart Rate (HR), an indicator of stress response, was correlated to muscle fatigue in the heat group (R = 0.59; p < 0.05) but was not correlated to MVC, twitch potentiation, and H reflex suppression. Sixty-one genes were differentially expressed after heat (41 genes >1.5-fold induced; 20 < 0.667 fold repressed). A strong correlation emerged between the session type (control or heat) and principal components (PC1) (R = 0.82; p < 0.005). Cell Signal Transduction, Metabolism, Gene Expression and Transcription, Immune System, DNA Repair, and Metabolism of Proteins were pathway domains with the largest number of genes regulated after acute whole body heat stress. Acute whole-body heat stress may offer a physiological stimulus for people with a limited capacity to exercise.

[Honors granted by the German Society for Child and Adolescent Psychiatry, Psychosomatics and Psychotherapy (DGKJP) and its predecessors]. / Die Ehrungen der Deutschen Gesellschaft für Kinder- und Jugendpsychiatrie, Psychosomatik und Psychotherapie e. V. (DGKJP) und ihrer Vorgängerorganisationen.

Honors granted by the German Society for Child and Adolescent Psychiatry, Psychosomatics and Psychotherapy (DGKJP) and its predecessors Abstract. Abstracts: This research on the "honors" granted by the German Society for Child and Adolescent Psychiatry, Psychosomatics and Psychotherapy (DGKJP) investigated all persons honored by the society from 1950 (following the postwar reestablishment of the society) up through 1990 (German reunification). We explored the adequacy of the honors regarding the professional ethics of the honorees during the NS-regime. Ethics violations included so-called T4-assessments (euthanasia) leading to death, working in "special units" where children were murdered using drugs, or any form of nontherapeutic experiments on humans. The Heinrich Hoffman Medal was first awarded in 1957, with honorary memberships being conferred from 1963 onward. From 1957 to 1990, the DGKJP awarded 19 honorary memberships and 9 Heinrich Hoffman Medal to 27 recipients (one person received both). Of those honored, three were detected as violators of professional ethics. After long internal discussions, the DGKJP had already distanced itself from Elisabeth Hecker (1895-1986), Hans-Alois Schmitz (1899-1973), and Werner Villinger (1887-1961). The ideology shared by these three was formulated by Villinger as the "ineducability" of their child victims because of an "inferiority paradigm." The rejection by the DGKJP went little noticed in public, and until 2021 was only briefly mentioned in the society's newsletter. Eleven honored persons were former members of the NSDAP without demonstrable ethical transgressions; the investigations are still ongoing for three others, whose ethical transgressions have neither been ruled out nor confirmed.

Effects of A Single Balance Training Session on Neural Excitability in Individuals With Chronic Ankle Instability.

CONTEXT: Individuals with chronic ankle instability (CAI) demonstrate reduced spinal reflex modulation and corticospinal excitability of the soleus, which may contribute to decreased balance performance. OBJECTIVE: To determine the effects of a single session of balance training on Spinal-reflexive excitability modulation and corticospinal excitability in those with CAI. DESIGN: Randomized controlled trials. SETTING: Research laboratory. PARTICIPANTS: Thirty participants with CAI were randomly assigned to the balance training (BAL) or control (CON) group. MAIN OUTCOME MEASURES: Modulation of soleus spinal-reflexive excitability was measured by calculating relative change in normalized Hoffmann reflexes (ratio of the H-reflex to the M-wave) from prone to single-leg standing. Corticospinal excitability was assessed during single-leg stance using transcranial magnetic stimulation, outcomes of which included active motor threshold (AMT), motor evoked potential, and cortical silent period (CSP). Balance performance was measured with center of pressure velocity in anterior to posterior and medial to lateral directions. Separate 2 × 2 repeated-measures analyses of variance were employed to determine the effect of group (BAL and CON) and time (baseline and posttraining) on each dependent variable. RESULTS: There were significant group by time interactions in the modulation of soleus spinal-reflexive excitability (F1,27 = 4.763, P = .04); CSP at 100% AMT (F1,27 = 4.727, P = .04); and CSP at 120% AMT (F1,27 = 16.057, P < .01). A large effect size suggests increased modulation of spinal-reflexive excitability (d = 0.81 [0.03 to 1.54]) of the soleus in BAL compared with CON at posttest, while CSP at 100% (d = 0.95 [0.17 to 1.70]) and 120% AMT (d = 1.10 [0.29 to 1.84]) was reduced in BAL when compared with CON at posttest. CONCLUSION: After a single session of balance training, individuals with CAI initiated increases in spinal reflex modulation and corticospinal excitability of the soleus. Thus, individuals with CAI who undergo balance training exhibit positive neural adaptations that are linked to improvements in balance performance.

Designing an Apparently Orbital-Symmetry-Forbidden [3s,5s]-Sigmatropic Shift through Transition-State Complexation and Stereoelectronic Effects.

The [3s,5s]-sigmatropic shift is an example of an orbital-symmetry forbidden pericyclic reaction that is outcompeted by the allowed [3s,3s]-sigmatropic shift. Density functional theory calculations are used to show that PdII -complexed systems with strategically placed substituents engaging in key stereoelectronic effects can select for the [3s,5s] process, thereby outcompeting both orbital-symmetry-allowed [3s,3s]- and [3s,5a]-shifts.

Do Antarafacial Cycloadditions Occur? Cycloaddition of Heptafulvalene with Tetracyanoethylene.

The cycloaddition of heptafulvalene (1) with tetracyanoethylene (TCNE) was previously described as an example of an antarafacial cycloaddition, a [π14 a +π2 s ] process that afforded only the trans cycloadduct by virtue of the edge-to-face approach of TCNE, facilitated by the S shape of 1. The reaction has been investigated in depth and found not to be a concerted antarafacial process. At low temperature, the reaction is observed to give a mixture of cis and trans cycloadducts as well as a [4+2] cycloadduct. The mixture of products is converted to the trans cycloadduct by equilibration upon warming to room temperature. Studies with diethyl 2,3-dicyanofumarate and -maleate confirmed the formation of cis cycloadducts. DFT studies at the M06-2X/6-311+G(2d,p) SCRF=acetone level of theory show that the originally proposed edge-to-face approach of TCNE to 1 is highly disfavored, whereas a stepwise mechanism involving the addition of TCNE at C2 to form a zwitterion followed by collapse at either C2' or C7' is energetically accessible. The Diels-Alder adduct is also formed in a stepwise reaction by competitive addition of TCNE at C4 of 1. These studies suggest that edge-to-face interactions are prohibitive in even the most favorable cases.

Fifty Years of a Dispute. A Triptych: Why Woodward?

This publication discusses R. B. Woodward's motivations, personality qualities, and chemical experiences that placed him in a perfect position to discover, along with Roald Hoffmann, the solution to the pericyclic no-mechanism problem, that is, to discover the Woodward-Hoffmann rules or, as Woodward preferred, the Principle of Conservation of Orbital Symmetry.

Why Hoffmann? His Chemistry.

Why was it that Roald Hoffmann was the perfect collaborator for R. B. Woodward for proposing the Principle of Conservation of Orbital Symmetry as the solution to the no-mechanism puzzle? This publication presents 17 "tools" that Hoffmann used extensively and effectively prior to the Woodward-Hoffmann collaboration that would he call upon reveal the mechanism of pericyclic reactions. In a sense, this is a biography of Hoffmann with a focus on his personal and professional skills as of May 5, 1964.

Sleeping Beauties in Chemistry. Oosterhoff, Havinga and Schlatmann: Four Years Before "The Woodward-Hoffmann Rules"†.

Several forerunners to the Woodward-Hoffmann rules appear in the chemical literature in the early 1960s. While these precedents refer to orbital symmetry and explain either electrocyclic reactions (Luitzen Oosterhoff, cited by Egbert Havinga and Jos Schlatmann in Tetrahedron in 1961) or some cycloaddition reactions (Kenichi Fukui, in a book chapter published in 1964), they did not attract any attention and did not serve to initiate any research prior to the publication of the five Woodward and Hoffmann communications in 1965. Even Woodward and Hoffmann were unaware of these precedents (though Hoffmann knew of Fukui's frontier orbital theory) until after they had completed the relevant portions of their work. The Oosterhoff-Havinga-Schlatmann story will be told in this paper; the Fukui story will be told in the next paper in this series on the history of the development of the Woodward-Hoffmann rules. Explanations for these precedents not being productive in solving the no-mechanism problem are discussed.

Kenichi Fukui, Frontier Molecular Orbital Theory, and the Woodward-Hoffmann Rules. Part II. A Sleeping Beauty in Chemistry†.

In 1964, Kenichi Fukui published a chapter in a book honoring the career of Robert S. Mulliken. While most of that chapter is a review of Fukui's previously published research dealing with frontier molecular orbital theory and organic reactions, one section provided a frontier molecular orbital explanation of the mechanism of the Diels-Alder reaction. Fukui concluded that the "symmetry relation of wave functions of both dienes and dienophiles" control the course of this reaction. Thus, Fukui's paper was a precursor to Woodward and Hoffmann's 1965 papers that proposed orbital symmetry control of what would later be termed "pericyclic reactions." Fukui published numerous papers in the 1950s and 1960s, many of which were expositions of his research in theoretical chemistry. Eight of those Fukui papers were direct precursors to his breakthrough 1964 publication. This paper presents the intellectual and scientific path that Fukui took from the early 1950s to 1964 to his award-winning publication.

Kenichi Fukui, Frontier Molecular Orbital Theory, and the Woodward-Hoffmann Rules. Part III. Fukui's Science and Technology, 1918-1965†.

In 1981, Kenichi Fukui shared the Nobel Prize in Chemistry with Roald Hoffmann "for their theories, developed independently, concerning the course of chemical reactions." In 1964, Fukui used his frontier molecular orbital theory to reveal the mechanism of the Diels-Alder reaction, a prototypical pericyclic cycloaddition reaction. Fukui revealed this molecular orbital symmetry explanation a year before Woodward and Hoffmann's first publication on "the conservation of orbital symmetry." As detailed in this paper, during the 1960s and early 1960s, Fukui was involved in several major programs in synthesis and polymer chemistry as well as aspects of theoretical chemistry quite distant from his contributions to the orbital symmetry research that preceded Woodward and Hoffmann. In this paper, a detailed examination of Fukui's pre-1965 research is discussed. This is Paper 4 - Part III of a trilogy that deals with Fukui's Nobel Prize research and is part of a 27-paper series on the history of the development of the Woodward-Hoffmann rules.

The Many Chemists Who Could Have Proposed the Woodward-Hoffmann Rules (Including Roald Hoffmann) But Didn't: The Theoretical and Physical Chemists†.

It is a reasonable question to ask, why, as of 1965 when the five Woodward-Hoffmann communication appeared, did no other physical chemist or chemical physicist or theoretical chemist discover the orbital symmetry rules for all pericyclic reactions? Two theoretical chemists - Luitzen Oosterhoff (in 1961) and Kenichi Fukui (in 1964) had discovered portions of the orbital symmetry rules; their stories appear in the papers immediately preceding this paper which is Paper 5 in a 27-paper series on the history of Woodward-Hoffmann rules. Concise yet telling stories of 19 other chemists who could have, might have, perhaps even should have discovered the Woodward-Hoffmann rules are presented with explanations as to why they did not do so. Social, political, and scientific explanations will summarize the analyses.

Kenichi Fukui, Frontier Molecular Orbital Theory, and the Woodward-Hoffmann Rules. Part I. The Person†.

Kenichi Fukui shared the 1981 Nobel Prize in Chemistry with Roald Hoffmann for "their theories, developed independently, concerning the course of chemical reactions." This is Paper 4 - Part I, of a three-part trilogy within a 27-paper series on the history of the development of the Woodward-Hoffmann rules. The personality and professional style of Fukui is discussed as well as his style of teaching and his mottos and sayings. A brief chronological history of his academic and professional life is presented along with a listing of Fukui's great flexibility in behaviors and in science. Lastly, a short list of Fukui's key awards is provided.