bluuebunny/crossref_metadata_2025 huggingface dataset:
Single molecule biochemistry using optical tweezers
Authors: Mehta Amit D. , Pullen Katherine A. , Spudich James A.
Published: July 2002

The use of optical trapping to create extremely compliant mechanical probes has ushered in a new field of biological inquiry, the mechanical and kinetic study of proteins at the single molecule level. This review focuses on three examples of such study and includes methods of extracting parameters of interest from the raw data such experiments generate.
Atractyloside‐induced release of cathepsin B, a protease with caspase‐processing activity
Authors: Vancompernolle Katia , Van Herreweghe Franky , Pynaert Gwenda , Van de Craen Marc , De Vos Kurt , Totty Nick , Sterling Alistar , Fiers Walter , Vandenabeele Peter , Grooten Johan
Published: July 2002

Recent data show that a strong relation exists in certain cells between mitochondria and caspase activation in apoptosis. We further investigated this relation and tested whether treatment with the permeability transition (PT)‐inducing agent atractyloside of Percoll‐purified mitochondria released a caspase‐processing activity. Following detection of procaspase‐11 processing, we further purified this caspase‐processing protease and identified it as cathepsin B. The purified cathepsin B, however, was found to be derived from lysosomes which were present as minor contaminants in the mitochondrial preparation. Besides procaspase‐11, caspase‐1 is also readily processed by cathepsin B. Procaspase‐2, ‐6, ‐7, ‐14 are weak substrates and procaspase‐3 is a very poor substrate, while procaspase‐12 is no substrate at all for cathepsin B. In addition, cathepsin B induces nuclear apoptosis in digitonin‐permeabilized cells as well as in isolated nuclei. All newly described activities of cathepsin B, namely processing of caspase zymogens and induction of nuclear apoptosis, are inhibited by the synthetic peptide caspase inhibitors z‐VAD.fmk, z‐DEVD.fmk and to a lesser extent by Ac‐YVAD.cmk.
Endogenous nitric oxide is responsible for the early loss of P450 in cultured rat hepatocytes
Authors: López-Garcı́a M.P
Published: July 2002

Loss of P450 during the early hours of monolayer formation is known to be the more serious limitation of primary cultured hepatocytes as an adequate model for the study of drug metabolism, toxicity and P450 induction. This study reports that endogenous nitric oxide (NO) formation is activated shortly after isolation by the classical collagenase‐based liver perfusion methods. Both rapid P450 loss and aerobic mitochondrial energy metabolism impairment – with subsequent changes on glucose metabolism – are directly related to the high local generation of the radical at this stage. These effects can be reverted by the sole addition of NO biosynthesis inhibitors during liver perfusion and early culture hours, which allows catalytically active P450 to be preserved at levels close to those of the intact liver.
Dehydroluciferyl‐AMP is the main intermediate in the luciferin dependent synthesis of Ap4A catalyzed by firefly luciferase
Authors: Fontes Rui , Ortiz Begoña , de Diego Anabel , Sillero Antonio , Günther Sillero Marı́a A.
Published: July 2002

It was previously assumed that E·LH2‐AMP was the intermediate complex in the synthesis of Ap4A catalyzed by firefly luciferase (EC 1.13.12.7), when luciferin (LH2) was used as cofactor. However, here we show that LH2 is partly transformed, shortly after the onset of the luciferase reaction, to dehydroluciferin (L) with formation of an E·L‐AMP complex which is the main intermediate for the synthesis of Ap4A. Formation of three more derivatives of LH2 were also observed, related to the production of light by the enzyme. CoA, a known stimulator of light production, inhibits the synthesis of Ap4A by reacting with the E·L‐AMP complex and yielding L‐CoA.
Tyrosine kinase activity is associated with CD44 in human neutrophils
Authors: Skubitz Keith M , Campbell Kenneth D , Skubitz Amy P.N
Published: July 2002

CD44 appears to be involved in signal transduction, however, the mechanism of this function is unclear. Protein kinase activity was detected in neutrophils associated with CD44. Most of the protein kinase activity associated with these antigens was tyrosine kinase activity. Src family kinases lyn and hck were found to account for much of the associated tyrosine kinase activity. The data suggest that associated tyrosine kinase activity may play a role in signal transduction from CD44 in neutrophils to regulate other cell functions.
UCP4, a novel brain‐specific mitochondrial protein that reduces membrane potential in mammalian cells
Authors: Mao Weiguang , Yu Xing Xian , Zhong Alan , Li Wenlu , Brush Jennifer , Sherwood Steven W , Adams Sean H , Pan Guohua
Published: July 2002

Uncoupling proteins (UCPs) are a family of mitochondrial transporter proteins that have been implicated in thermoregulatory heat production and maintenance of the basal metabolic rate. We have identified and partially characterized a novel member of the human uncoupling protein family, termed uncoupling protein‐4 (UCP4). Protein sequence analyses showed that UCP4 is most related to UCP3 and possesses features characteristic of mitochondrial transporter proteins. Unlike other known UCPs, UCP4 transcripts are exclusively expressed in both fetal and adult brain tissues. UCP4 maps to human chromosome 6p11.2–q12. Consistent with its potential role as an uncoupling protein, UCP4 is localized to the mitochondria and its ectopic expression in mammalian cells reduces mitochondrial membrane potential. These findings suggest that UCP4 may be involved in thermoregulatory heat production and metabolism in the brain.
A new fluorescence‐based, hydrophobic photolabeling technique for analyzing membrane‐associated proteins
Authors: Hess D , Isenberg G
Published: July 2002

We introduce a new, fluorescent and photoactivatable fatty acid derivative (SANU) for hydrophobic labelling of membrane‐bound proteins. The technique allows fast and highly sensitive screening of hydrophobically inserting proteins analyzed by SDS‐PAGE with a detection limit below 0.1 pmol. A reliable calculation of labelling efficiencies is achieved by simultaneous densitometry of fluorescence and protein staining. We have applied the new technique on the membrane inserting protein talin, G‐actin, and, as a negative control, on RNase, which only binds electrostatically to negatively charged lipid interfaces. In several ways superior to radiolabelling, we can recommend this technique for all laboratories under any circumstances.
Structural and biochemical analysis of Ras‐effector signaling via RalGDS
Authors: Vetter I.R. , Linnemann T. , Wohlgemuth S. , Geyer M. , Kalbitzer H.R. , Herrmann C. , Wittinghofer A.
Published: July 2002

The structure of the complex of Ras with the Ras‐binding domain of its effector RalGDS (RGS‐RBD), the first genuine Ras‐effector complex, has been solved by X‐ray crystallography. As with the Rap‐RafRBD complex (Nasser et al., 1995), the interaction is via an inter‐protein β‐sheet between the switch I region of Ras and the second strand of the RGS‐RBD sheet, but the details of the interactions in the interface are remarkably different. Mutational studies were performed to investigate the contribution of selected interface residues to the binding affinity. Gel filtration experiments show that the Ras·RGS‐RBD complex is a monomer. The results are compared to a recently determined structure of a similar complex using a Ras mutant (Huang et al., 1998) and are discussed in relation to partial loss‐of‐function mutations and the specificity of Ras versus Rap binding.
High endothelial cells synthesize and degrade sLex. Putative implications for L‐selectin‐dependent recognition
Authors: Majuri Marja-Leena , Räbinä Jarkko , Niittymäki Jaana , Tiisala Sinikka , Mattila Pirkko , Aavik Einari , Miyasaka Masayuki , Renkonen Ossi , Renkonen Risto
Published: July 2002

L‐selectin guides lymphocytes into peripheral lymphoid tissues by recognizing glycoprotein ligands decorated with 6‐sulfated sialyl Lewis x (sulfo sLex). Here we have used a rat peripheral lymph node high endothelial cell line (Ax) to study in detail the synthesis, expression and degradation of sLex epitope. We show here that Ax cells possess active α(1,3)fucosyltransferase Fuc‐TVII, the enzyme responsible for the final fucosylation of sialyl‐N‐acetyllactosamine during sLex synthesis, and express sLex on the cell surface. Furthermore, these cells degrade sLex, primarily by desialylating it to neutral Lex epitopes by α(2,3)sialidase(s).
Mechanical manipulation of bone and cartilage cells with ‘optical tweezers’
Authors: Walker Lesley M. , Holm Åsa , Cooling Leanne , Maxwell Lori , Öberg Åke , Sundqvist Tommy , El Haj Alicia J.
Published: July 2002

The single beam optical gradient trap (optical tweezers) uses a single beam of laser light to non‐invasively manipulate microscopic particles. Optical tweezers exerting a force of approximately 7 pN were applied to single bone and cartilage derived cells in culture and changes in intracellular calcium levels were observed using Fluo‐3 labelling. Human derived osteoblasts responded to optical tweezers with an immediate increase in [Ca2+]i that was inhibited by the addition of a calcium channel blocker nifedipine. Force applied to different regions of cells resulted in a variable response. [Ca2+]i elevation in response to load was lower in rat femur derived osteoblasts, and not apparent in primary chondrocytes and the osteocytic cell line (MLO Y4).
The tRNA N2,N2‐dimethylguanosine‐26 methyltransferase encoded by gene trm1 increases efficiency of suppression of an ochre codon in Schizosaccharomyces pombe
Authors: Niederberger Christian , Gräub Remo , Costa Annie , Desgrès Jean , Schweingruber M.Ernst
Published: July 2002

In the majority of eukaryotic tRNAs, the guanosine at position 26 is modified by a dimethyl group, but so far a function of this modification has not been detected. We isolated the Schizosaccharomyces pombe gene, trm1, encoding the tRNA N2,N2‐dimethylguanosine‐26 methyltransferase. Strains having the gene deleted completely lack N2,N2‐dimethylguanosine. In strains carrying the weak ochre tRNA suppressor sup3‐i, deletion of trm1 abolishes suppression indicating that the trm1 deletion acts as an antisuppressor mutation. The result suggests that in vivo N2,N2‐dimethylguanosine‐26 increases the capacity of the sup3‐i serine tRNA to translate the UAA (ochre) codon.
Prediction of a ligand‐induced conformational change in the catalytic core of Cdc25A
Authors: Kolmodin Karin , Åqvist Johan
Published: July 2002

The cell cycle control phosphatases Cdc25 are dual specificity phosphatases that dephosphorylate both phosphothreonine and phosphotyrosine residues on their substrate proteins. The determination of the apo‐protein structure of Cdc25A revealed that this enzyme has a completely different fold compared to all other phosphatases crystallised to date. The conformation of the active site residues does not seem very suitable for catalysis in this unliganded structure. We have studied some structural features of the Cdc25A apo‐structure and a modelled Cdc25A‐ligand complex by molecular dynamics simulations. The simulations predict a conformational change in the peptide backbone of the complex, which is not observed in the apo‐structure. This ligand‐induced conformational change yields a structure that is similar to other protein tyrosine phosphatase‐ligand complexes that have been crystallised. The change in conformation takes place in the position between a serine and a glutamic acid residue in the phosphate binding loop. We suggest that this type of conformational change is an important molecular switch in the catalytic process.
Supramolecular organization of the subsarcolemmal cytoskeleton of adult skeletal muscle fibers. A review
Authors: Berthier Christine , Blaineau Sylvie
Published: July 2002

This review is focused on the composition and organization of the junctional subsarcolemmal cytoskeleton of adult muscle fibers. The cytoskeleton of muscle fibers is organized in functionally distinct compartments and the subsarcolemmal cytoskeleton itself can be broadly divided into junctional (myotendinous junction, neuromuscular junction and costameres) and non‐junctional domains. In junctional zones three different multimolecular cytoskeletal complexes coexist: the focal adhesion‐type, the spectrin‐based and the dystrophin vs utrophin‐based membrane skeleton systems. These complexes extend over several levels, from intracytoplasmic to subsarcolemmal and transmembranous; their common feature is the anchorage of actin filaments emanating from the intracytoplasmic level. The different cytoskeletal proteins, their putative roles and their interactions with various signaling pathways are presented here in detail. The subsarcolemmal cytoskeleton complexes are thought to play distinct physiological roles (membrane stabilization, force transmission to extracellular matrix, ionic channel anchorage, etc) but their colocalization on the three sarcolemmal junctional domains strongly suggests interrelated or common functions.
Effect of polymer molecular weight and addition of calcium stearate on response of MG63 osteoblast‐like cells to UHMWPE particles
Authors: Dean D. D. , Lohmann C. H. , Sylvia V. L. , Köster G. , Liu Y. , Schwartz Z. , Boyan B. D.
Published: July 2002

Periprosthetic osteolysis and implant loosening is associated with the presence of ultrahigh molecular weight polyethylene (UHMWPE) wear debris particles. Osteoblast phenotypic expression in vitro is affected by UHMWPE particles, suggesting that bone formation may also be affected by wear debris. Here we tested the hypothesis that the response of osteoblasts to UHMWPE can be modified by changes in UHMWPE particle chemistry. We used four different commercially available preparations of GUR UHMWPE particles to determine if chemical composition (±Ca‐stearate) or polymer molecular weight (3.1–4.2 million or 5.4–6.5 million g/mol) modulates osteoblast response. Particles were characterized by size distribution, morphology, and number of particles added to the culture medium. They had an average equivalent circle diameter ranging from 0.46–1.26 μm. MG63 cell response was assessed by measuring cell number, cellular and cell layer alkaline phosphatase, and prostaglandin E2 (PGE2) production. There were dose‐dependent effects of the particles on cell response. Cell number and PGE2 production were increased, while alkaline phosphatase specific activity was decreased. In addition, there was a marked difference between cultures treated with particles containing Ca‐stearate and as a function of polymer molecular weight. Particles of higher molecular weight caused a greater stimulation of proliferation and inhibition of alkaline phosphatase than particles of lower molecular weight. The presence of Castearate exerted a more pronounced depression of osteoblast phenotype as well as a significantly greater increase in PGE2 release by the cells. The present study shows that chemical composition and polymer molecular weight of UHMWPE are capable of modulating osteoblast response to particles. The results suggest that osteoblast differentiation is inhibited by UHMWPE particles, whereas cell proliferation and PGE2 production are stimulated. This may have direct effects on osteoblasts and bone formation, but also paracrine effects on cells of the monocytic lineage inducing bone resorption and promoting inflammation which may lead to aseptic loosening. The present results suggest that the cellular events in aseptic loosening may be modulated or even accelerated by changes in the composition of the UHMWPE used to fabricate implants. © 2001 Orthopaedic Research Society. Published by Elsevier Science Ltd. All rights reserved.
Chronic depolarization induced by veratridine increases the survival of rat retinal ganglion cells ‘in vitro’
Authors: Fernandes Pereira Simão Pedro , Giestal de Araujo Elizabeth
Published: July 2002

During the last decades it has been shown that trophic molecules released by target, afferent and glial cells play a pivotal role controlling neuronal cell death. Trophic molecules are able to inhibit this regressive event during development as well as during degenerative diseases. One of the mechanisms involved in the control of neuronal survival by afferent cells requires the release of trophic molecules stimulated by electrical activity. It has been demonstrated that veratridine (a depolarizing agent that keeps the Na+ channels opened) induces an increase in neuronal survival. In the present work we show that 3 μM veratridine induced a two‐fold increase on the survival of retinal ganglion cells after 48 h in culture. The veratridine effect was inhibited by 50 μM amiloride (an inhibitor of Ca2+ channels), 25 μM benzamil (an inhibitor of Na+ channels), 30 μM dantrolene and 7.5 μM caffeine (both inhibitors of Ca2+ release from the endoplasmatic reticulum) and 10 μM BAPTA‐AM (an intracellular Ca2+ chelator). However, 5 μM nifedipine (a selective inhibitor of voltage‐dependent l‐type Ca2+ channels) and 100 μM MK 801 (an inhibitor of NMDA receptors) did not block the veratridine effect. On the other hand, treatment with 10 μM genistein (an inhibitor of tyrosine kinase enzymes), 20 μM fluorodeoxyuridine (an inhibitor of cell proliferation) or 10 μM atropine (an antagonist of muscarinic receptors) completely abolished the effect of veratridine. Taken together, our results indicate that veratridine increases the survival of rat retinal ganglion cells through mechanisms involving Na+ influx, intracellular Ca2+ release, activation of tyrosine kinase enzymes and cellular proliferation. They also indicate that cholinergic activity plays an important role in the veratridine effect.
Cholinergic activity modulates the survival of retinal ganglion cells in culture: the role of M1 muscarinic receptors
Authors: Pereira S.P.F. , Medina S.V. , Araujo E.G.
Published: July 2002

The control of natural cell death is mediated by neurotrophins released by target, afferent and glial cells. In the present work we show that treatment of retinal cells ‘in vitro’ for 48 h with 25 μM carbamylcholine induced a two‐fold increase in retinal ganglion cells survival. This effect was dose‐dependent and mediated by M1 receptors since it could be blocked by 1 μM telenzepine (a M1 receptor antagonist) and mimicked by 200 μM oxotremorine (a M1 receptor agonist). The effect of carbamylcholine was abolished by 10 μM BAPTA‐AM (an intracellular Ca2+ chelator), 30 μM dantrolene (an inhibitor of ryanodinic receptors), 500 nM H‐89 (an inhibitor of PKA), 1.25 μM chelerythrine chloride (an inhibitor of PKC) and 50 μM PD‐98059 (a MEK inhibitor). Treatment with 10 μM genistein (an inhibitor of tyrosine kinase), 25 μM LY‐294002 (a PI‐3 kinase blocker), 30 nM brefeldin‐A (a blocker of polypeptides release), 50 nM K‐252a (a Trk receptor inhibitor) and 20 μM fluorodeoxyuridine (an inhibitor of cell proliferation) totally inhibited the effect of carbamylcholine. Taken together our results indicate that muscarinic activity controls the survival of retinal ganglion cells through a mechanism involving the release of polypeptides and activation of Irk receptors.
Relapse prevention in schizophrenia: attitudes of neurologists-psychiatrists
Authors: Bergiannaki J.D. , Hatzimanolis J. , Liappas J. , Sakkas P.N. , Stefanis C.N.
Published: July 2002

The overall high relapse rates observed in schizophrenia are attributed to several causes. One important factor influencing satisfactory prevention of relapse is the lack of consistent treatment strategies among medical doctors, especially neurologists-psychiatrists. Nearly one-third of the members of the Hellenic Society of Neurology and Psychiatry were asked to fill in anonymously a structured questionnaire on their treatment attitudes and prescribing tactics regarding schizophrenic patients both after the first schizophrenic episode and after multiple episodes. The majority of Greek neurologists-psychiatrists seem to adopt prescribing habits that approximate the current international standards for prevention of schizophrenic relapse. Their attitudes regarding the treatment and prevention of relapse for the first schizophrenic episode and first relapse are determined from multiple factors. These are: the expected relapse rates after the first episode, the expected prevalence of extrapyramidal side effects following a long-term neuroleptic treatment, the patient’s expected treatment compliance after the first episode, the doctor’s experience with treating schizophrenics, and lastly the knowledge of current literature on the topic. These results point to the need for continuing education, especially of the younger mental health professionals and those working in the private sector, addressing the issue of the actual risk of developing side effects from the treatment. In due course, benefits could result for everyday psychiatric practice and the patients’ compliance with treatment.
Rating antidepressant efficacy with naturalistic live versus structured videotaped interviews
Authors: Corruble E , Sabran V , Payan C , Puech AJ , Fermanian J , Guelfi JD
Published: July 2002

Two different methods were compared in the assessment of depressive symptomatology improvement: live naturalistic (N) performed by the patient's therapist, and from videotape record of structured clinical interview (VSI) assessed by an independent rater out of five psychiatrists.

Sixty-one newly admitted depressed inpatients, with a Montgomery and Asberg Depression Rating Scale (MADRS) total score above 20, were assessed before antidepressant treatment (DO), after 10 days (D10) and 4 weeks of treatment (D28). Assessments were based on the MADRS and the Depression Retardation Rating Scale (DRRS) for both N and VSI methods, and on the SCL-90-R for self-rating.

With the MADRS, the N method was shown to be more sensitive to symptomatology change than the VSI method, but the VSI method was more correlated to self-assessment than the N method was. However, these results were not replicated on the DRRS, for which an underscoring with the VSI method was evidenced as compared to the N method.

As shown in other studies, the poorest agreement between the two methods was evidenced at DO, suggesting a “novelty effect” particularly with the VSI method. This “novelty effect” may be all the more pronounced if a personality disorder is associated to depression. Consequently, information concerning each patient before rating videotapes is needed, as well as investigations in the field of depression and personality disorders.

The greater change observed in MADRS with the N method as compared to the VSI method, may be due non-specific factors related mostly to therapist expectations by comparison to neutral raters. This hypothesis should be tested in the placebo group of a double-blind study, and, if confirmed, the use of VSI methods, by minimising non-specific factors of improvement due to therapist expectations, may decrease the placebo response in antidepressant drug trials.
HIV IN OLDER AMERICANS: AN EPIDEMIOLOGIC PERSPECTIVE
Authors: Lieberman Rochel
Published: July 2002

The elderly population is increasing as baby boomers are beginning to approach retirement. People 65 years of age or older already constitute approximately one eighth of the U.S. population; this proportion is expected to double in the next 50 years. Older Americans have their own population‐specific health challenges, such as Alzheimer's disease, osteoporosis, adult‐onset diabetes, prostate cancer, menopause, and hypertension. Human immunodeficiency virus (HIV) infection and acquired immunodeficiency syndrome (AIDS) are seldom discussed within this community. Prevention, counseling, testing, and education efforts are not being directed their way. In addition, few practitioners are experts both in HIV and health problems associated with aging, resulting in misdiagnosis, especially in the early stages when AIDS symptoms such as fatigue, weight loss, night sweats, and diminished appetite are dismissed as part of the aging process.

Very few HIV‐related social support services have been aimed at the needs of the elderly, perhaps because older Americans are not suspected to be sexually active or are assumed to be in a monogamous, heterosexual relationship. Older Americans are not suspected of drug use. Yet many are sexually active, often demonstrating risky sexual behavior, such as dispensing with the use of condoms; and the isolation that frequently accompanies old age can lead to alcoholism and injectable drug use.

This article examines methods suggested in the literature both in terms of primary and secondary prevention of HIV/AIDS in older Americans. The cost of these efforts is enumerated, and organizations who gear their efforts in reaching and educating older Americans regarding their risks are described.
Ninjaflex vs Superflab: A comparison of dosimetric properties, conformity to the skin surface, Planning Target Volume coverage and positional reproducibility for external beam radiotherapy
Authors: Robertson Fiona M. , Couper Megan B. , Kinniburgh Margaret , Monteith Zoe , Hill Gareth , Pillai Sanka Andiappa , Adamson Douglas J. A.
Published: March 2021

Background and purpose

When planning and delivering radiotherapy, ideally bolus should be in direct contact with the skin surface. Varying air gaps between the skin surface and bolus material can result in discrepancies between the intended and delivered dose. This study assessed a three‐dimensional (3D) printed flexible bolus to determine whether it could improve conformity to the skin surface, reduce air gaps, and improve planning target volume coverage, compared to a commercial bolus material, Superflab.

Materials and methods

An anthropomorphic head phantom was CT scanned to generate photon and electron treatment plans using virtual bolus. Two 3D printing companies used the material Ninjaflex to print bolus for the head phantom, which we designated Ninjaflex1 and Ninjaflex2. The phantom was scanned a further 15 more times with the different bolus materials in situ allowing plan comparison of the virtual to physical bolus in terms of planning target volume coverage, dose at the prescription point, skin dose, and air gap volumes.

Results

Superflab produced a larger volume and a greater number of air gaps compared to both Ninjaflex1 and Ninjaflex2, with the largest air gap volume of 12.02 cm3. Our study revealed that Ninjaflex1 produced the least variation from the virtual bolus clinical goal values for all modalities, while Superflab displayed the largest variances in conformity, positional accuracy, and clinical goal values. For PTV coverage Superflab produced significant percentage differences for the VMAT and Electron3 plans when compared to the virtual bolus plans. Superflab also generated a significant difference in prescription point dose for the 3D conformal plan.

Conclusion

Compared to Superflab, both Ninjaflex materials improved conformity and reduced the variance between the virtual and physical bolus clinical goal values. Results illustrate that custom‐made Ninjaflex bolus could be useful clinically and may improve the accuracy of the delivered dose.
Interfacial Reactions in the Bonding Zones of Explosively Welded Tantalum to Stainless Steel Sheets
Authors: Paul Henryk , Chulist Robert , Mania Izabela , Schell Norbert , Lityńska-Dobrzyńska Lidia
Published: March 2021

The microstructure of the interfacial layers of explosively welded Ta/stainless steel (SS) and Ta/Cu/SS composites is investigated by X‐ray synchrotron radiation, scanning (SEM), and transmission (TEM) electron microscopies. SEM analyses show that all interfaces between joined sheets undergo wave‐shaped deformation with the solidified melt regions situated preferentially in the wave vortexes and at the wave crests. These reaction regions show a nonuniform distribution of phases in terms of chemical composition with elements belonging to both neighboring sheets. According to TEM analyses and synchrotron X‐ray measurements, the solidified melt regions between Ta and SS predominantly consist of brittle, amorphous, or nanocrystalline phases that are not observed in equilibrium phase diagrams. The microstructure of the solidified melt near the Ta/Cu interface is dominated by Cu and Ta nanoparticles and small dendrites, typically less than 100 nm in diameter, whereas nanosized crystalline phases with complex chemical compositions are identified near the Cu/SS interface.
Core‐Shell Faujasite@Aqueous Miscible Organic‐Layered Double Hydroxides Composites with Tunable Acid/Base Properties for One‐Pot Synthesis of Ethyl trans‐α‐Cyanocinnamate
Authors: Rodaum Chadatip , Suttipat Duangkamon , Morey Julien , Atithep Thassanant , Witoon Thongthai , Wattanakit Chularat
Published: March 2021

Bifunctional acid‐base catalysts have been developed by fabricating core‐shell faujasite@aqueous miscible organic‐layered double hydroxides (FAU@AMO‐LDHs) composites via the growth of AMO‐LDHs on zeolite surfaces. Interestingly, by adjusting the acid/base properties of the composites, the one‐pot synthesis of ethyl trans‐α‐cyanocinnamate via deacetalization‐Knoevenagel reaction can be achieved up to 90% yield. In contrast, almost no desired products can be observed in cases of isolated zeolites and AMO‐LDHs, demonstrating the synergistic effect of zeolites and AMO‐LDHs as acid‐base catalysts. These findings open up new perspectives of the development of tunable acid‐base zeolite@LDHs composites in an acid‐base tandem reaction, which can selectively produce ethyl trans‐α‐cyanocinnamate up to 90% yield.
Photogenerated Charge Separation between Polar Crystal Facets Under a Spontaneous Electric Field
Authors: Liu Bin , Yang Heqing , Liu Shengzhong
Published: March 2021

Until now, the photogenerated charge separation mechanism is not clear in photocatalysis. Based on the structures at the atomic scale of the polar crystal facets with photocatalytic activities, a general separation model of photogenerated charge between polar facets under a spontaneous electric field is presented. This charge separation model is proven by photo‐induced selective redox reactions on polar planes, photovoltaic and rectification effects in the polar direction orientated thin films, and electric field assisted assembly and alignment of semiconductor nanowires grown along the polar direction. This polar structure is similar to a semiconductor p–n junction, which can control the movement of electronic carriers and can be used to fabricate high‐efficiency photocatalysts and electronic and optoelectronic devices based on a new principle.
Designing Rules and Optimization of Triboelectric Nanogenerator Arrays
Authors: Shao Jiajia , Yang Yi , Yang Ou , Wang Jie , Willatzen Morten , Wang Zhong Lin
Published: March 2021

A triboelectric nanogenerator (TENG) is an effective means for the conversion of mechanical energy into electricity. Although Maxwell's displacement current is the underline mechanism of TENGs, the spatial and temporal variations of the electric field and electric displacement remain elusive, which prohibits an effective optimization of the energy conversion process. Here, the electric field distribution and energy dynamics of TENGs is determined using 3D mathematical modeling. The electrical energies stored in TENGs and extracted into the external circuit are calculated quantitatively whereby the ratio of the two, defined as the output efficiency, is obtained. Then, the power density and energy density of TENGs are defined. Utilizing the principle of virtual work, the minimum required external force–time relationship is evaluated. The influence of device parameters, geometry, and optimum conditions are discussed systematically so as to determine general optimization guidelines for TENGs. In addition, although the fringing electric field is practically inevitable, adjustments of the gap distance between neighboring TENG devices to assure that an optimized fringing electric field is “leaked”, is demonstrated to lead to improvement in a TENG array. Then, for the first time, this work presents universal design rules and holistic optimization strategies for the network structure of TENGs.
Multiple SclerosisIs Rare in Epstein–Barr Virus–Seronegative Children withCentral Nervous SystemInflammatory Demyelination
Authors: Nourbakhsh Bardia , Cordano Christian , Asteggiano Carlo , Ruprecht Klemens , Otto Carolin , Rutatangwa Alice , Lui Allysa , Hart Janace , Flanagan Eoin P. , James Judith A. , Waubant Emmanuelle
Published: March 2021

Although Epstein–Barr virus (EBV) is hypothesized to be a prerequisite for multiple sclerosis (MS), up to 15% of children with a diagnosis of MS were reported to be EBV‐seronegative. When re‐evaluating 25 EBV‐seronegative children out of 189 pediatric patients with a diagnosis of clinically isolated syndrome/MS, we found anti–myelin oligodendrocyte glycoprotein (MOG) antibody in 11 of 25 (44%) EBV‐seronegative but only 9 of 164 (5.5%,p < 0.001) EBV‐seropositive patients. After critical review, MS remained a plausible diagnosis in only 4 of 14 EBV‐seronegative/MOG antibody–negative patients. In children with an MS‐like presentation, EBV seronegativity should alert clinicians to consider diagnoses other than MS, especially MOG‐antibody disease. ANN NEUROL 2021;89:1234–1239
Solvent‐Switched Oxidation Selectivities with O2: Controlled Synthesis of α‐Difluoro(thio)methylated Alcohols and Ketones
Authors: Liu Chi , Zhu Chuanle , Cai Yingying , Jiang Huanfeng
Published: March 2021

The solvent‐switched hydroxylation and oxygenation of α‐difluoro(thio)methylated carbanions with molecular oxygen under mild conditions are reported. This strategy tames the redox reactions of the in situ generated hydroperoxy difluoromethylsulfides, in which solvent‐bonding can alter their reactivity and switch the oxidation selectivities. These controllable three‐component reactions of gem‐difluoroalkenes, thiols and molecular oxygen afford various useful α‐difluoro(thio)methylated alcohols and ketones in high yields. Significantly, this protocol has been applied in the synthesis different bioactive molecules. Mechanism studies enable the detection of the hydroperoxy difluoromethylsulfide intermediates and exclude the thiol‐based radical pathway.
Chemically Fueled Self‐Assembly in Biology and Chemistry
Authors: Das Krishnendu , Gabrielli Luca , Prins Leonard J.
Published: March 2021

Life is a non‐equilibrium state of matter maintained at the expense of energy. Nature uses predominantly chemical energy stored in thermodynamically activated, but kinetically stable, molecules. These high‐energy molecules are exploited for the synthesis of other biomolecules, for the activation of biological machinery such as pumps and motors, and for the maintenance of structural order. Knowledge of how chemical energy is transferred to biochemical processes is essential for the development of artificial systems with life‐like processes. Here, we discuss how chemical energy can be used to control the structural organization of organic molecules. Four different strategies have been identified according to a distinguishable physical‐organic basis. For each class, one example from biology and one from chemistry are discussed in detail to illustrate the practical implementation of each concept and the distinct opportunities they offer. Specific attention is paid to the discussion of chemically fueled non‐equilibrium self‐assembly. We discuss the meaning of non‐equilibrium self‐assembly, its kinetic origin, and strategies to develop synthetic non‐equilibrium systems.
An Efficient Interfacial Synthesis of Two‐Dimensional Metal–Organic Framework Nanosheets for Electrochemical Hydrogen Peroxide Production
Authors: Wang Mengjun , Dong Xu , Meng Zhaodong , Hu Zhiwei , Lin Yan‐Gu , Peng Chun‐Kuo , Wang Hongshuai , Pao Chih‐Wen , Ding Songyuan , Li Youyong , Shao Qi , Huang Xiaoqing
Published: March 2021

Two‐dimensional (2D) metal–organic framework nanosheets (MOF NSs) play a vital role in catalysis, but the most preparation is ultrasonication or solvothermal. Herein, a liquid–liquid interfacial synthesis method has been developed for the efficient fabrication of a series of 2D Ni MOF NSs. The active sites could be modulated by readily tuning the ratios of metal precursors and organic linkers (RM/L). The Ni MOF NSs display highly RM/L dependent activities towards 2e oxygen reduction reaction (ORR) to hydrogen peroxide (H2O2), where the Ni MOF NSs with the RM/L of 6 exhibit the optimal near‐zero overpotential, ca. 98 % H2O2 selectivity and production rate of ca. 80 mmol gcat−1 h−1 in 0.1 M KOH. As evidenced by X‐ray absorption fine structure spectroscopy, the coordination environment of active sites changed from saturation to unsaturation, and the partially unsaturated metal atoms are crucial to create optimal sites for enhancing the electrocatalysis.
Enzyme‐like Supramolecular Iridium Catalysis Enabling C−H Bond Borylation of Pyridines with meta‐Selectivity
Authors: Trouvé Jonathan , Zardi Paolo , Al‐Shehimy Shaymaa , Roisnel Thierry , Gramage‐Doria Rafael
Published: March 2021

The use of secondary interactions between substrates and catalysts is a promising strategy to discover selective transition metal catalysts for atom‐economy C−H bond functionalization. The most powerful catalysts are found via trial‐and‐error screening due to the low association constants between the substrate and the catalyst in which small stereo‐electronic modifications within them can lead to very different reactivities. To circumvent these limitations and to increase the level of reactivity prediction in these important reactions, we report herein a supramolecular catalyst harnessing Zn⋅⋅⋅N interactions that binds to pyridine‐like substrates as tight as it can be found in some enzymes. The distance and spatial geometry between the active site and the substrate binding site is ideal to target unprecedented meta‐selective iridium‐catalyzed C−H bond borylations with enzymatic Michaelis–Menten kinetics, besides unique substrate selectivity and dormant reactivity patterns.
Hierarchical Metal–Polymer Hybrids for Enhanced CO2Electroreduction
Authors: Jia Shuaiqiang , Zhu Qinggong , Chu Mengen , Han Shitao , Feng Ruting , Zhai Jianxin , Xia Wei , He Mingyuan , Wu Haihong , Han Buxing
Published: March 2021

The design of catalysts with high activity, selectivity, and stability is key to the electroreduction of CO2. Herein, we report the synthesis of 3D hierarchical metal/polymer–carbon paper (M/polymer‐CP) electrodes by in situ electrosynthesis. The 3D polymer layer on CP (polymer‐CP) was first prepared by in situ electropolymerization, then a 3D metal layer was decorated on the polymer‐CP to produce the M/polymer‐CP electrode. Electrodes with different metals (e.g. Cu, Pd, Zn, Sn) and various polymers could be prepared by this method. The electrodes could efficiently reduce CO2to desired products, such as C2H4, CO, and HCOOH, depending on the metal used. For example, C2H4could be formed with a Faradaic efficiency of 59.4 % and a current density of 30.2 mA cm−2by using a very stable Cu/PANI‐CP electrode in an H‐type cell. Control experiments and theoretical calculations showed that the 3D hierarchical structure of the metals and in situ formation of the electrodes are critical for the excellent performance.
Copper‐Catalyzed Borylative Methylation of Alkyl Iodides with CO as the C1 Source: Advantaged by Faster Reaction of CuH over CuBpin
Authors: Wu Fu‐Peng , Wu Xiao‐Feng
Published: March 2021

CuH and CuBpin are versatile catalysts and intermediates in organic chemistry. However, studies that involve both CuH and CuBpin in the same reaction is still rarely reported due to their high reactivity. Now, a study on CuH‐ and CuBpin‐catalyzed borylative methylation of alkyl iodides with CO as the C1 source is reported. Various one carbon prolongated alkyl boranes (RCH2Bpin and RCH(Bpin)2) were produced in moderate to good yields from the corresponding alkyl iodides (RI). In this cooperative system, CuH reacts with alkyl iodide faster than CuBpin.
Effects of ash compositions in Zhundong coal on its ash fusion behavior and crystal phase transformation
Authors: Wang Chang'an , Sun Ruijin , Tang Guantao , Yuan Maobo , Du Yongbo , Che Defu
Published: March 2021

The ash‐related issues hinder the safe utilization of Zhundong coal, closely relevant to its ash compositions. Previous studies mainly focused on the experimental methods and the selection of ash composition benchmark was restricted to a specific coal sample with limited element types, ignoring the comprehensive elemental interaction. Here, the impacts of eight compositions on ash fusion and crystal phase transformation behaviors were taken into consideration. Moreover, FactSage software was employed to further elucidate the transformation mechanism of ash composition with the increasing temperature. The results showed that the refractory forsterite and merwinite disappeared but more magnesioferrite was present with an increase in ferric oxide content, resulting in the decrease of ash fusion temperatures. The refractory substances, such as forsterite, perovskite, periclase, and larnite, occurred successively with the increasing ratio of basic oxide to acid oxide. The slag content had reached its maximum at 1200°C, up to 90% as the content of CaO was 16%, which was corresponding to that the flowing temperature descended to the lowest point around 1200°C with 16% CaO. With the rising temperature, more slag appeared and the composition species declined, related with the generation of fusible compounds containing Fe and Na at high temperature. The present work can play a guiding role in safe and clean use of Zhundong coal.
Influence of nano silica hybrid expandable graphite on flammability, thermal stability, and mechanical property of polypropylene/polyamide 6 blends
Authors: Bai Zhuyu , Wang Na , Chen Shaopeng , Guo Xincheng , Guo Jianbing , Qin Jun , Chen Xiaolang , Lu Zongcheng
Published: March 2021

Silica (SiO2) nanohybrid expandable graphite (nEG) particles fabricated through one‐step method are used as an efficient flame retardant for polypropylene (PP)/polyamide 6 (PA6) blends. The effect of nEG on the flammability, thermal stability, crystallization behaviors, and mechanical properties of PP/PA6 composites is investigated by using limit oxygen index (LOI), UL‐94 test, cone calorimeter test (CCT), thermogravimetric analysis, differential scanning calorimetry, Fourier transform infrared, scanning electron microscopy, and mechanical tests. Compared with pure expandable graphite (EG), nEG improves the flame retardancy of composites. The results of LOI show that LOI of PP/PA6/nEG10 and PP/PA6/nEG15 composites are 26.0% and 27.2%, respectively. But the LOI values of PP/PA6/EG10 and PP/PA6/EG15 composites are 25.7% and 26.9%, respectively. The UL‐94 test results show that PP/PA6/nEG10 composites reach V‐1 level when the nEG content is only 10%. However, the PP/PA6 composites with 10% EG does not pass the UL‐94 test. In addition, PP/PA6 composites with 15% nEG can reach V‐0 level. The CCT results further show that nEG has a higher flame‐retardant efficiency than pure EG for PP/PA6 blends. The thermal stability of PP/PA6/nEG composites is better than that of PP/PA6/EG composites. The mechanical property tests indicate that nEG is more conducive to maintain the tensile and impact strengths of PP/PA6 blends than EG due to the enhanced compatibility and interfacial adhesion.
Copolymerization behavior of diallyldimethylammonium chloride‐nonionic macromonomer in water‐ether mixture solution and flotation performance of the copolymer for treating oily wastewater
Authors: He Jie , Duan Ming , Wang Xiujun , Wang Manlin , Jing Bo , Liu Shuai , Fang Shenwen
Published: March 2021

Copolymerization of cationic monomer and nonionic macromonomer in water‐ether mixture solution is useful for preparing the functional polymer. Copolymer of diallyldimethylammonium chloride (DMDAAC) and a nonionic block polyether macromonomer (PEP‐65) has been found that has very well reverse demulsification performance, but the polymerization phenomenon cannot be described by any reported polymerization method. In this paper, the copolymerization behavior including polymer mechanism, polymerization kinetics, and reactivity rate of DMDAAC and PEP‐65 in the mixture solution of water and propylene glycol methyl ether (PGME) was studied for explaining the special copolymerization phenomenon and its flotation performance for treating oily wastewater was also investigated. The results showed that DMDAAC‐PEP‐65 copolymerization in water‐PGME mixture solution has four stages and has both characteristics of emulsion polymerization and dispersion polymerization. In addition, the copolymer also has excellent flotation performance.
Child Sexual Abuse: Children at Risk Are Being Ignored
Authors:   Paediatric Research Across the Midlands
Published: March 2021

Key Practitioner Messages

Evidence exists for the concomitant presence of sexual abuse with other forms of maltreatment; however, this audit study suggests that questions that could arouse the suspicion of CSA are not being asked consistently.

It is important for healthcare professionals to specifically consider sexual abuse when seeing children who present for Child Protection Medical Assessments.
Serum alkaline phosphatase levels are associated with coronary artery calcification patterns and plaque vulnerability
Authors: Ren Yongkui , Li Xinsheng , Wang Shuai , Pan Weili , Lv Haichen , Wang Minxian , Zhou Xuchen , Xia Yunlong , Yin Da
Published: March 2021

Objectives

This study aimed to investigate the association of serum alkaline phosphatase (ALP) with calcification patterns and plaque morphology detected by intravascular ultrasound (IVUS) in acute coronary syndrome (ACS) patients.

Background

ALP has been shown to predict vascular calcification and long‐term cardiovascular events. However, the relationship between ALP and vascular calcification patterns or plaque morphology remains unclear.

Methods

In total, 328 ACS patients who underwent IVUS examinations were screened from January 2017 to December 2018; among them, 234 eligible participants were grouped according to the tertiles of ALP levels (<68, 68–80, and >80 IU/L). Demographic data and IVUS parameters were documented and analyzed.

Results

After adjusting for potential confounders, independent associations were observed between ALP and the presence of coronary calcification, spotty calcification, minimum lumen area (MLA) ≤ 4.0 mm2, and plaque burden (PB) > 70%. Compared with the lowest ALP tertile group, the highest ALP group had higher risks of calcification (odds ratio [OR], 2.85; 95% confidence interval [95%CI], 1.38–5.90; p = .005), spotty calcification (OR, 1.86; 95%CI, 1.09–3.84; p = .012), MLA≤4.0 mm2 (OR, 3.32; 95%CI, 1.51–7.28; p = .003), and PB > 70% (OR, 4.59; 95%CI, 1.83–11.50; p = .001). Similar results were found when ALP was analyzed as a continuous variable or a category variate according to the cut‐off value determined by the receiver operating characteristic curve analysis. Furthermore, the model including clinical factors and ALP significantly improved the predictive power for coronary calcification, spotty calcification, MLA≤4.0 mm2, and PB > 70%.

Conclusion

Our findings suggest that ALP may be a potential predictive biomarker for calcification and plaque vulnerability.