bluuebunny/crossref_metadata_2025 huggingface dataset:
Sequence and functional characterization of RNase P RNA from the chl a/b containing cyanobacterium Prochlorothrix hollandica
Authors: Fingerhut Christiane , Schön Astrid
Published: July 2002

Only a few complete sequences and very limited functional data are available for the catalytic RNA component of cyanobacterial RNase P. The RNase P RNA from the chl a/b containing cyanobacterium Prochlorothrix hollandica belongs to a rarely found structural subtype with an extended P15/16 domain. We have established conditions for optimal in vitro ribozyme activity, and determined the kinetic parameters for cleavage of pre‐tRNATyr. Analysis of pre‐tRNA mutants revealed that the T‐stem sequence only plays a modulating role, whereas the CCA end is essential for efficient product formation.
The secretases that cleave angiotensin converting enzyme and the amyloid precursor protein are distinct from tumour necrosis factor‐α convertase
Authors: Parvathy S , Karran Eric H , Turner Anthony J , Hooper Nigel M
Published: July 2002

Angiotensin converting enzyme (ACE) and the Alzheimer's amyloid precursor protein are cleaved from the membrane by zinc metalloproteinases termed ACE secretase and α‐secretase, respectively. Tumour necrosis factor‐α (TNF‐α) convertase (ADAM 17) is a recently identified member of the adamalysin family of mammalian zinc metalloproteinases that is involved in the production of TNF‐α and possibly in the cleavage of other membrane proteins. Using two different cell‐free assays we were unable to detect significant cleavage and secretion of ACE by TNF‐α convertase. In addition, there was a different effect of three hydroxamic acid‐based inhibitors (batimastat, compound 1 and compound 4) towards TNF‐α convertase as compared to ACE secretase and α‐secretase. Thus TNF‐α convertase would appear to be distinct from, but possibly related to, the secretases that cleave ACE and the amyloid precursor protein.
Synthetic mammalian C‐type natriuretic peptide forms large cation channels
Authors: Kourie Joseph I.
Published: July 2002

We report the first evidence that synthetic human C‐type natriuretic peptide‐22 and the OaC‐type natriuretic peptide‐39(18–39), a 22 amino acid fragment of the OaC‐type natriuretic peptide‐39 from platypus venom, can function directly by forming a novel voltage‐gated weakly cation‐selective channel in negatively charged artificial lipid bilayer membranes. The channel activity is characterized by a tendency for inactivation at negative voltages, e.g. −60 and −70 mV, whereas at positive voltages the channel is fully open. The channel has a maximal cord conductance of 546±23 pS (n=16) and shows weak outward rectification. The sequence and the permeability ratios were P
+
K:P
+
Cs:P
+
Na:P
+
choline 1:0.88:0.76:0.13, respectively. The addition of 50 mM TEA+

cis
(a blocker of outwardly rectifying K+ channels), 20 mM Cs+

cis
(a blocker of inwardly rectifying K+ channels) or 0.5 mM glibenclamide
cis
(a blocker of ATP‐sensitive K+ channels) to the cis chamber did not affect the conductance or the kinetics of the OaC‐type natriuretic peptide‐39(18–39)‐formed channels (n=2–5). It is concluded that the weak cation selectivity, large conductance and high open probability as well as their voltage dependency are consistent with the ability of these peptides to cause that loss of compartmentation of the membrane, which is a characteristic feature of adverse conditions that cause C‐type natriuretic peptide‐related pathologies.
Shortened microsatellite d(CA)21 sequence down‐regulates promoter activity of matrix metalloproteinase 9 gene
Authors: Shimajiri Shohei , Arima Nobuyuki , Tanimoto Akihide , Murata Yoshitake , Hamada Tetsuo , Wang Ke-Yong , Sasaguri Yasuyuki
Published: July 2002

One characteristic elements in the promoter of the matrix metalloproteinase 9 (MMP‐9) gene is the d(CA) repeat. To investigate whether this element regulates the transcription of the MMP‐9 gene and its enzymatic activities, we sequenced the promoter region isolated from esophageal carcinoma cell lines. TE9 cells with low MMP‐9 enzymatic activity had the number of d(CA) repeats shortened from 21 to 14 or 18. TE8, TE10 and TE11 cells with high MMP‐9 activities had 21 or 23 d(CA) repeats. Luciferase assays using MMP‐9 promoter containing 18, 14 or 0 d(CA) repeats showed transcriptional activities which were 50, 50 or 5%, respectively, of the level achieved with promoter containing 21 d(CA) repeats. Sequence analysis of the promoter of 223 Japanese subjects revealed that most had two alleles with 20, 21 or 22 d(CA) repeats, whereas six had one or two alleles with 14, 18 or 19 d(CA) repeats. We postulate that length alteration of the d(CA) repeat causes phenotypic differences among carcinoma cells and that microsatellite instability may contribute to the polymorphism of d(CA) repeat length.
Pseudomyxoma peritonei — a heterogenous disease
Authors: Shen D.H , Ng T.Y , US Khoo , Xue W.C , Cheung A.N.Y
Published: July 2002

Objective: To evaluate the origin of pseudomyxoma peritonei (PMP) in Chinese women. Methods: The clinicopathologic features of 15 cases of PMP were reviewed. Immunostaining using antibodies for CK7 and CK20 was performed in the ovarian, appendiceal and peritoneal lesions of these cases. Results: Appendiceal pathology was documented in five cases, including four mucinous cystadenoma and one simple mucocele. Eight ovarian tumors were found, including seven mucinous cystadenocarcinomas of low malignant potential and one mucinous cystadenoma. Synchronous ovarian and appendiceal lesions were discovered in three cases. One patient had adenocarcinoma of the pancreas. The origin of mucin production was not known in four cases with metastatic adenocarcinoma found in two of them. Immunoreactivity for CK20 was demonstrated in the tissues derived from the peritoneum, ovary, appendix and pancreas while only 23% (3 out of 13 women) of the peritoneal lesions and 33% (2 out of 6 women) of the ovarian tumors were immunoreactive for CK7. Conclusions: PMP is a heterogeneous lesion, which may develop from mucinous metaplasia of the peritoneum or from appendiceal, or ovarian lesions. Careful examination of the ovary and appendix with performance of appendectomy is advised in every case of PMP. Immunohistochemical examination of the peritoneal, ovarian or appendiceal lesions using antibodies, in particular that for CK7 would help in defining the origin of mucin production.
Perceived relevance and quality of POM journals: a decade later
Authors: Barman Samir , Hanna Mark D , LaForge R.Lawrence
Published: July 2002

This research is a 10‐year update on the rankings of perceived relevance and quality of selected Production and Operations Management (POM) journals that was reported by Barman et al. (1991) [Journal of Operations Management 10 (2), 194–212)]. The results show some changes in the perceptions of journals over the past decade. Some journals are perceived to be extremely relevant to POM research, but not particularly of “high” quality. For other journals, the reverse is true — “high” quality is perceived but the published studies are not considered particularly relevant to POM. The Journal of Operations Management remained atop the relevance rankings and retained its position among the top three journals for quality. The study identifies factors that the respondents say influence their perception of journal quality. Finally, the paper finds some evidence that association with the editorial board of a journal affects one’s perceptions of the quality and relevance of that journal.
IL‐16 is differentially expressed in the developing human fetal brain by microglial cells in zones of neuropoesis
Authors: Schwab J.M. , Schluesener H.J. , Seid K. , Meyermann R.
Published: July 2002

Microglial cells are regulators of tissue homeostasis in the adult central nervous system and readily participate in pathological processes, orchestrating tissue remodeling. Cytokines produced by microglial cells are markers of cell activation and contribute to reactive processes. In this paper, we have studied the expression of IL‐16 (leukocyte chemoattractant factor), a natural soluble ligand to the CD4 molecule, in human fetal brains from the 11th to the 20th. week of gestation by immunohistochemistry. Interleukin (IL)‐16+ cells were detected already at the 11th gestational week, accumulating with aging in cortical layers (P<0.0001) at the 16th and 19th week, and reaching maximum numbers in the 20th week. Most IL‐16+ microglia (>80%) revealed morphological hallmarks of activated microglia. We observed that IL‐16 cells coexpress LCA (>80%) and MRP‐8, an activation‐associated Ca2+ binding S‐100 family member (>80%). In contrast, only few IL‐16+ cells proliferated (PCNA+, 20–40%) or co‐expressed the HLA‐DR, ‐DP, or ‐DQ antigen (<10%), and rare coexpression with CD68 (20–40%) was detected until 17th week. No coexpression with CD4, CD8 or CD20 was detected. Furthermore, we observed accumulation of IL‐16+ microglia in zones of neuronal proliferation, migration and differentiation. Increasing numbers of IL‐16+ cells were detected in bordering zones adjacent to the basal ganglia. Our data suggests that the early presence of IL‐16+ microglia exert a CD4‐independent function‐mediating activation, and chemotaxis of microglia precursors during neuronal development. In addition, IL‐16 immunoreactivity might be a helpful tool to determine distinct developmental stages of microglial cells during fetal central nervous system ontogeny.
Otx genes in the development and evolution of the vertebrate brain
Authors: Boyl Pietro Pilo , Signore Massimo , Annino Alessandro , Barbera Juan Pedro Martinez , Acampora Dario , Simeone Antonio
Published: July 2002

Most of the gene candidates for the control of developmental programmes that underlie brain morphogenesis in vertebrates are the orthologues of Drosophila genes coding for signalling molecules or transcription factors. Among these, the orthodenticle group, including the Drosophila orthodenticle (otd) and the vertebrate Otx1 and Otx2 genes, is mostly involved in fundamental processes of anterior neural patterning. In mouse, Drosophila and intermediate species otd/Otx genes have shown a remarkable similarity in expression pattern suggesting that they could be part of a conserved control system operating in the brain and different from that coded by the HOX complexes controlling the hindbrain and spinal cord. In order to verify this hypothesis, a series of mouse models have been generated in which the functions of the murine Otx genes were: (i) fully inactivated, (ii) replaced with each other, and (iii) replaced with the Drosophilaotd gene. The data obtained highlight a crucial role for the Otx genes in specification, regionalization and terminal differentiation of rostral central nervous system and lead to hypothesize that modification of their regulatory control may have influenced the morphogenesis and evolution of the brain.
Repeated prenatal corticosteroid administration delays astrocyte and capillary tight junction maturation in fetal sheep
Authors: Huang W.L. , Harper C.G. , Evans S.F. , Newnham J.P. , Dunlop S.A.
Published: July 2002

Glucocorticoids are powerful regulators of cell differentiation and maturation. Their synthetic counterparts, the corticosteroids, are used widely in obstetric practice to enhance fetal lung maturation in cases of threatened preterm birth. Here we examined the effects of repeated corticosteroid administration on astrocyte and capillary tight junction development in the fetal sheep brain, selecting the corpus callosum for analysis. Pregnant ewes were given saline or betamethasone (0.5 mg/kg) at 104, 111, 118 and 124 days gestation. Lambs were delivered at term, terminally anaesthetized and transcardially perfused. Transverse semi‐thin sections of the corpus callosum were cut and immuno‐stained with antibody against glial fibrillary acidic protein (GFAP). Ultra‐thin sections were examined in the electron microscope. The percentage area of GFAP staining was reduced in the corticosteroid‐treated group compared to control (5.2 vs. 8.7%, P<0.05). The expression of GFAP in peri‐capillary and parenchymal astrocytes was also reduced compared to control (peri‐capillary: 3.0 vs. 9.5 μm2; parenchymal: 14.6 vs. 29.4 μm2, P<0.05). Furthermore, capillary tight junction maturation was delayed compared to control. Immature ‘type II’ junctions were more common in the corticosteroid‐treated group (63 vs. 22%, P<0.05), whereas more mature ‘type III’ junctions were less common (27 vs. 65%, P<0.05). Our data suggest that repeated corticosteroids delay both astrocyte and capillary tight junction maturation. The implications for clinical practice are as yet unknown.
A regression analytical approach to estimate the onset of activity of antidepressants
Authors: Müller H , Möller H-J
Published: July 2002

The onset of activity of antidepressants is a clinically and theoretically important criterion of efficacy. We estimated the onset of activity by an intraindividual regression analytical approach. It is assumed that efficient treatment causes a fast shift of depression scores from a baseline level to an end level. From this assumption follows a limited number of opportunities for the onset of activity to occur. These opportunities correspond to different regression models which are estimated for each patient's depression course. The day of onset is concluded from the regression model which produces the best fit to the empirical depression curve. Results of a double-blind clinical trial comparing mianserin and amitriptyline are reported (n = 28). The methodological approach confirms that observer ratings by physicists show a significantly earlier onset of activity than self ratings by the patients. The D-S also shows a significantly earlier onset of activity of mianserin compared to amitriptyline. The discussion emphasises methodological aspects.
Month of birth in deficit and non-deficit schizophrenic patients
Authors: Dollfus S. , Brazo P. , Langlois S. , Gourevitch R. , Dassa D. , Besse F. , Van Der Elst A. , Thibaut F. , Delamillieure P. , Chabot B. , Guelfi J.D. , Petit M.
Published: July 2002

In order to test the hypothesis that an excess of summer births is a risk factor for deficit syndrome, the month of birth was studied in 53 deficit schizophrenic patients compared to 158 non-deficit patients. No significant difference in terms of month of birth or season of birth was observed between deficit and non-deficit patients, suggesting that summer births might not be a risk factor for deficit schizophrenia.
Alterations in DNA methylation profiles in cancellous bone of postmenopausal women with osteoporosis
Authors: Zhou Yu , Yang Ling , Wang Hong , Chen Xi , Jiang Wei , Wang Zhicong , Liu Shuping , Liu Yuehong
Published: June 2020

Osteoporosis is characterized by systemic microarchitecture impairment and bone loss, which ultimately lead to fragility fractures. This disease is most common in older people, especially in postmenopausal women. Cancellous bone is affected by osteoporosis earlier than cortical bone, and DNA methylation microarray analysis of the hip cancellous bone of patients with osteoarthritis revealed differential methylation. In view of the important role of cancellous bone in bone development, we examined genome‐wide DNA methylation profiles in the cancellous bone from patients with postmenopausal osteoporosis versus healthy postmenopausal women using Illumina 850K methylation microarray analysis. Under a threshold of P < 0.05, we obtained a total of 8973 differentially methylated genes, such as SOX6, ACE, SYK and TGFB3. Under a threshold of P < 0.05 and |△β| > 0.2, a total of 17 and 34 key differentially methylated genes were further identified at the promoter region and cytosine‐ phosphate‐ guanine (CpG) islands (such as PRKCZ, GNA11 and COL4A1), respectively. PLEKHA2, PLEKHB1, PNPLA7, SCD, MGST3 and TSNAX were the most common differentially methylated genes at both the promoter region and CpG islands. Five important signaling pathways, including the calcium signaling pathway, the cyclic guanosine phospho‐protein kinase G (cGMP‐PKG) signaling pathway, endocytosis, the Rap1 signaling pathway and the AMPK signaling pathway were identified. Our study may be suitable as a basis for exploring the mechanisms underlying osteoporosis in postmenopausal women.
Inductively Coupled Plasma Mass Spectrometry Analysis of Environmental Samples for the Quantification of Potentially Toxic Species
Authors: Teuma‐Castelletti Robert , Sadiq Nausheen W. , Beauchemin Diane
Published: June 2020

The analysis of environmental samples is widely carried out to determine if a soil is safe for agricultural use, if water is safe to drink, if the air that we breathe can make us sick, how far reaching is pollution, if a contaminated site has been suitably remediated, etc. This article discusses how inductively coupled plasma mass spectrometry (ICPMS) can be used to this end. Indeed, with detection limits at the parts per trillion or even parts per quadrillion level, depending on the element and the instrument, ICPMS is very advantageous for the detection and quantification of toxic or potentially toxic species in environmental samples. This article describes sample preparation for ICPMS analysis and instrument calibration to yield accurate quantitative results. This includes the precautions that are often required, which vary depending on the type of analysis, sample matrix, instrument, and elements to be determined. It also includes techniques that can be coupled to ICPMS to increase its capabilities, such as laser ablation or electrothermal vaporization for direct solid analysis and liquid chromatography, gas chromatography, or capillary electrophoresis for speciation analysis, as speciation information is lost in the inductively coupled plasma (ICP) where all compounds are atomized.
Monitoring of Dynamic Processes during Detection of Cardiac Biomarkers Using Silicon Nanowire Field‐Effect Transistors
Authors: Li Jie , Kutovyi Yurii , Zadorozhnyi Ihor , Boichuk Nazarii , Vitusevich Svetlana
Published: June 2020

Numerous sensitive nanobiosensors are reported for various bioassay applications as a result of the development of materials science and nanotechnology. Among these sensors, nanowire (NW) field‐effect transistors (FETs) represent one of the most promising practical biosensors for ultrasensitive clinical diagnostic tools. Most studies mainly focus on how to achieve a lower detection limit but pay less attention to the long settling time effect for the detection of very small concentrations of molecules in a solution. In this study, single silicon NW FETs with long‐term stability is fabricated to investigate the settling time process at small concentrations of cardiac biomarkers relevant to myocardial diseases. It is found that the settling time strongly depends on the type of molecule, its charge state and analyte concentrations. For low concentrations, the time for measurement signals to settle down is relatively long. Therefore, it is essential to understand the settling time effect in Si NW FET‐based biosensing processes to ensure the accuracy and reliability of the detection signal. An alternative approach is demonstrated to circumvent the long measurement time by utilizing reaction kinetics parameters for the fast determination of low‐concentration detection, which also benefits the optimal balance between suitable detection time and reliable detection results.
Bromination of α‐Diazo Phenylacetate Derivatives Using Cobalt(II) Bromide
Authors: Wang Haifeng , Sun Xiangli , Hu Manman , Zhang Xiaoyi , Xie Lele , Gu Shuangxi
Published: June 2020

A method for the bromination of α‐diazo phenylacetate derivatives using cobalt(II) bromide is described. This bromination reaction features a short reaction time, broad substrate scope, operational simplicity, acid‐free conditions, and gram‐scalability.

magnified image
High‐Throughput Analysis of Materials for Chemical Looping Processes
Authors: Singstock Nicholas R. , Bartel Christopher J. , Holder Aaron M. , Musgrave Charles B.
Published: June 2020

Chemical looping is a promising approach for improving the energy efficiency of many industrial chemical processes. However, a major limitation of modern chemical looping technologies is the lack of suitable active materials to mediate the involved subreactions. Identification of suitable materials has been historically limited by the scarcity of high‐temperature (>600 °C) thermochemical data to evaluate candidate materials. An accuratethermodynamic approach is demonstrated here to rapidly identify active materials which is applicable to a wide variety of chemical looping chemistries. Application of this analysis to chemical looping combustion correctly classifies 17/17 experimentally studied redox materials by their viability and identifies over 1300 promising yet previously unstudied active materials. This approach is further demonstrated by analyzing redox pairs for mediating a novel chemical looping process for producing pure SO2 from raw sulfur and air which could provide a more efficient and lower emission route to sulfuric acid. 12 promising redox materials for this process are identified, two of which are supported by previous experimental studies of their individual oxidation and reduction reactions. This approach provides the necessary foundation for connecting process design with high‐throughput material discovery to accelerate the innovation and development of a wide range of chemical looping technologies.
Performance of double cropping silage maize with plastic mulch in the North China Plain
Authors: Liang Shuoshuo , Zhang Xiying , Lu Yang , An Ping , Yan Zongzheng , Chen Suying
Published: June 2020

North China Plain farmers often use maize (Zea mays L.) silage for dairy cows. Double cropping of maize may be a feasible way to reduce annual water use and land required to produce feed. The objective of this study was to evaluate the possibility of growing a double crop of silage maize with and without plastic film mulch. An experiment was conducted between 2015 and 2018 and contained three treatments: double‐cropped (maize) plastic film mulch (2 M+PM), double‐cropped (maize) without plastic film mulch (2 M), and double‐cropped winter wheat (Triticum aestivum L.) and summer maize (WW+SM). Net income, yield, water use efficiency (WUE), and annual water use were determined. The results indicated that silage dry matter yield and WUE were improved by 45.6 and 31.5%, respectively, using plastic film mulch compared with no mulch. Total water footprint in producing the silage was also reduced by 24% using plastic film mulch. The annual water use was reduced by 150–190 mm with 2 M+PM or 2 M compared with WW+SM. Average net income was 429, 926, and 1,008 $ ha−1 in 2 M, 2 M+PM, and WW+SM, respectively. The results indicated that the advantages of the double‐silage maize system lie in the reduction in the amount of land required to produce maize silage for dairy cows. However, due to the limited growth duration for the double maize, high silage water contents reduced silage quality.
Subspecies differentiation in an enigmatic chaparral shrub species
Authors: Huang Yi , Morrison Glen R. , Brelsford Alan , Franklin Janet , Jolles Diana D. , Keeley Jon E. , Parker V. Thomas , Saavedra Natalie , Sanders Andrew C. , Stoughton Thomas R. , Wahlert Gregory A. , Litt Amy
Published: June 2020

Premise

Delimiting biodiversity units is difficult in organisms in which differentiation is obscured by hybridization, plasticity, and other factors that blur phenotypic boundaries. Such work is more complicated when the focal units are subspecies, the definition of which has not been broadly explored in the era of modern genetic methods. Eastwood manzanita (Arctostaphylos glandulosaEastw.) is a widely distributed and morphologically complex chaparral shrub species with much subspecific variation, which has proven challenging to categorize. Currently 10 subspecies are recognized, however, many of them are not geographically segregated, and morphological intermediates are common. Subspecies delimitation is of particular importance in this species because two of the subspecies are rare. The goal of this study was to apply an evolutionary definition of “subspecies” to characterize structure within Eastwood manzanita.

Methods

We used publicly available geospatial environmental data and reduced‐representation genome sequencing to characterize environmental and genetic differentiation among subspecies. In addition, we tested whether subspecies could be differentiated by environmentally associated genetic variation.

Results

Our analyses do not show genetic differentiation among subspecies of Eastwood manzanita, with the exception of one of the two rare subspecies. In addition, our environmental analyses did not show ecological differentiation, though limitations of the analysis prevent strong conclusions.

Conclusions

Genetic structure within Eastwood manzanita does not correspond to current subspecies circumscriptions, but rather reflects geographic distribution. Our study suggests that subspecies concepts need to be reconsidered in long‐lived plant species, especially in the age of next‐generation sequencing.
Use of Research Evidence Generated by Youth: Conceptualization and Applications in Diverse U.S. K‐12 Educational Settings
Authors: Ozer Emily J. , Abraczinskas Michelle , Voight Adam , Kirshner Ben , Cohen Alison K. , Zion Shelley , Glende Jillian R. , Stickney Dane , Gauna Reyes , Lopez Solicia E. , Freiburger Keegan
Published: June 2020

Youth‐Led Participatory Action Research (YPAR) is a social justice‐focused approach for promoting social change and positive youth development in which youth conduct systematic research and actions to improve their schools and communities. Although YPAR is oriented to generating research for action, with evidence‐based recommendations often aimed at influencing adults with power over settings and systems that shape youths’ lives, we have little understanding of how YPAR evidence influences the thinking and/or actions of adult policymakers or practitioners. In general, the participatory research field lacks a theoretically informed “use of research evidence” lens, while the use of evidence field lacks consideration of the special case and implications of participatory research. To start to address these gaps, this paper presents a conceptual linkage across these two fields and then provides six illustrative case examples across diverse geographic, policy, and programmatic contexts to demonstrate opportunities and challenges in the use of YPAR evidence for policy and practice. Our illustrative focus here is on U.S. K‐12 educational contexts, the most‐studied setting in the YPAR literature, but questions examined here are relevant to YPAR and other systems domestically and internationally, including health, educational, and legal systems.

Highlights

The use of research evidence (URE) field identifies characteristics of research and conditions that strengthen URE.

Youth‐led Participatory Action Research is a special case for factors that influence research use.

Six case examples across diverse K‐12 contexts illustrate facilitators and barriers for YPAR use.

We propose next steps for community psychology research and action to promote the study and use of YPAR evidence.
Should we be concerned about COVID‐19 with nonhuman primates?
Authors: Santos Wesley José , Guiraldi Lívia Maísa , Lucheis Simone Baldini
Published: June 2020

The coronavirus disease 2019 pandemic has radically changed the human activities worldwide. Although we are still learning about the disease, it is necessary that primatologists, veterinarians, and all that are living with nonhuman primates (NHP) be concerned about the probable health impacts as these animals face this new pandemic. We want to increase discussion with the scientific community that is directly involved with these animals, because preliminary studies report that NHP may become infected and develop symptoms similar to those in human beings.
A Single‐Atom Manipulation Approach for Synthesis of Atomically Mixed Nanoalloys as Efficient Catalysts
Authors: Zhou Xuan , Li Kai , Lin Yunxiang , Song Li , Liu Jincheng , Liu Yu , Zhang Lingling , Wu Zhijian , Song Shuyan , Li Jun , Zhang Hongjie
Published: June 2020

Synthesis of well‐defined atomically mixed alloy nanoparticles on desired substrates is an ultimate goal for their practical application. Herein we report a general approach for preparing atomically mixed AuPt, AuPd, PtPd, AuPtPd NAs(nanoalloys) through single‐atom level manipulation. By utilizing the ubiquitous tendency of aggregation of single atoms into nanoparticles at elevated temperatures, we have synthesized nanoalloys on a solid solvent with CeO2 as a carrier and transition‐metal single atoms as an intermediate state. The supported nanoalloys/CeO2 with ultra‐low noble metal content (containing 0.2 wt % Au and 0.2 wt % Pt) exhibit enhanced catalytic performance towards complete CO oxidation at room temperature and remarkable thermostability. This work provides a general strategy for facile and rapid synthesis of well‐defined atomically mixed nanoalloys that can be applied for a range of emerging techniques.
Hierarchically Structured Allotropes of Phosphorus from Data‐Driven Exploration
Authors: Deringer Volker L. , Pickard Chris J. , Proserpio Davide M.
Published: June 2020

The discovery of materials is increasingly guided by quantum‐mechanical crystal‐structure prediction, but the structural complexity in bulk and nanoscale materials remains a bottleneck. Here we demonstrate how data‐driven approaches can vastly accelerate the search for complex structures, combining a machine‐learning (ML) model for the potential‐energy surface with efficient, fragment‐based searching. We use the characteristic building units observed in Hittorf's and fibrous phosphorus to seed stochastic (“random”) structure searches over hundreds of thousands of runs. Our study identifies a family of hierarchically structured allotropes based on a P8 cage as principal building unit, including one‐dimensional (1D) single and double helix structures, nanowires, and two‐dimensional (2D) phosphorene allotropes with square‐lattice and kagome topologies. These findings yield new insight into the intriguingly diverse structural chemistry of phosphorus, and they provide an example for how ML methods may, in the long run, be expected to accelerate the discovery of hierarchical nanostructures.
Deuteriodifluoromethylation and gem‐Difluoroalkenylation of Aldehydes Using ClCF2H in Continuous Flow
Authors: Fu Wai Chung , Jamison Timothy F.
Published: June 2020

The deuteriodifluoromethyl group (CF2D) represents a challenging functional group due to difficult deuterium incorporation and unavailability of precursor reagents. Herein, we report the use of chlorodifluoromethane (ClCF2H) gas in the continuous flow deuteriodifluoromethylation and gem‐difluoroalkenylation of aldehydes. Mechanistic studies revealed that the difluorinated oxaphosphetane (OPA) intermediate can proceed via alkaline hydrolysis in the presence of D2O to provide α‐deuteriodifluoromethylated benzyl alcohols or undergo a retro [2+2] cycloaddition under thermal conditions to provide the gem‐difluoroalkenylated product.
A Mixed‐Valence {Fe13} Cluster Exhibiting Metal‐to‐Metal Charge‐Transfer‐Switched Spin Crossover
Authors: Wen Wen , Meng Yin‐Shan , Jiao Cheng‐Qi , Liu Qiang , Zhu Hai‐Lang , Li Ya‐Ming , Oshio Hiroki , Liu Tao
Published: June 2020

It is promising and challenging to manipulate the electronic structures and functions of materials utilizing both metal‐to‐metal charge transfer (MMCT) and spin‐crossover (SCO) to tune the valence and spin states of metal ions. Herein, a metallocyanate building block is used to link with a FeII‐triazole moiety and generates a mixed‐valence complex {[(Tp4‐Me)FeIII(CN)3]9[FeII4(trz‐ph)6]}⋅[Ph3PMe]2⋅[(Tp4‐Me)FeIII(CN)3] (1; trz‐ph=4‐phenyl‐4H‐1,2,4‐triazole). Moreover, MMCT occurs between FeIII and one of the FeII sites after heat treatment, resulting in the generation of a new phase, {[(Tp4‐Me)FeII(CN)3][(Tp4‐Me)FeIII(CN)3]8 [FeIIIFeII3(trz‐ph)6]}⋅ [Ph3PMe]2⋅[(Tp4‐Me)FeIII(CN)3] (1 a). Structural and magnetic studies reveal that MMCT can tune the two‐step SCO behavior of 1 into one‐step SCO behavior of 1 a. Our work demonstrates that the integration of MMCT and SCO can provide a new alternative for manipulating functional spin‐transition materials with accessible multi‐electronic states.
Synthesis of a Stable N‐Hetero‐RhI‐Metallacyclic Silanone
Authors: Takahashi Shintaro , Nakaya Kazuki , Frutos María , Baceiredo Antoine , Saffon‐Merceron Nathalie , Massou Stéphane , Nakata Norio , Hashizume Daisuke , Branchadell Vicenç , Kato Tsuyoshi
Published: June 2020

A novel N‐hetero‐RhI‐metallacyclic silanone 2 has been synthesized. The silanone 2, showing an extremely large dimerization energy (ΔG=+86.2 kcal mol−1), displays considerable stability and persists in solution up to 60 °C. Above 120 °C, an intramolecular Csp3−H insertion occurs slowly over a period of two weeks leading to the bicyclic silanol 5. The exceptional stability of 2, related to the unusual electronic and steric effects of RhI‐substituent, should allow for a more profound study and understanding of these new species. Furthermore, the metallacyclic silanone 2 presents two reactive centers (Si=O and Rh), which can be involved depending upon the nature of reagents. Of particular interest, the reaction with H2 starts with the hydrogenation of RhI center leading to the corresponding RhIII‐dihydride complex 7 and it undergoes a cis/trans‐isomerization via a particular mechanism, demonstrating that addition‐elimination processes can also happen for silanones just like for their carbon analogues!
Solar‐Assisted eBiorefinery: Photoelectrochemical Pairing of Oxyfunctionalization and Hydrogenation Reactions
Authors: Choi Da Som , Kim Jinhyun , Hollmann Frank , Park Chan Beum
Published: June 2020

Inspired by natural photosynthesis, biocatalytic photoelectrochemical (PEC) platforms are gaining prominence for the conversion of solar energy into useful chemicals by combining redox biocatalysis and photoelectrocatalysis. Herein, we report a dual biocatalytic PEC platform consisting of a molybdenum (Mo)‐doped BiVO4 (Mo:BiVO4) photoanode and an inverse opal ITO (IO‐ITO) cathode that gives rise to the coupling of peroxygenase and ene‐reductase‐mediated catalysis, respectively. In the PEC cell, the photoexcited electrons generated from the Mo:BiVO4 are transferred to the IO‐ITO and regenerate reduced flavin mononucleotides to drive ene‐reductase‐catalyzed trans‐hydrogenation of ketoisophrone to (R)‐levodione. Meanwhile, the photoactivated Mo:BiVO4 evolves H2O2 in situ via a two‐electron water‐oxidation process with the aid of an applied bias, which simultaneously supplies peroxygenases to drive selective hydroxylation of ethylbenzene into enantiopure (R)‐1‐phenyl‐1‐hydroxyethane. Thus, the deliberate integration of PEC systems with redox biocatalytic reactions can simultaneously produce valuable chemicals on both electrodes using solar‐powered electrons and water.
Effects of swim‐with‐dolphin tourism on the behaviour of spinner dolphins, at Samadai Reef in the Egyptian Red Sea
Authors: Shawky Ahmed M. , Christiansen Fredrik , Ormond Rupert
Published: June 2020

Spinner dolphins, Stenella longirostris, are the primary target for marine mammal tourism in Egypt. The present study investigated the short‐term effects of tourist presence on the behaviour of spinner dolphins at Sha'ab Samadai (Samadai Reef), in the southern Egyptian Red Sea.

The reef has a large central lagoon where a population of spinner dolphin regularly rest from mid‐morning to mid‐afternoon; visitors are permitted to snorkel in the southern part of the lagoon, but not in the northern closed zone that the dolphins mainly use.

Dolphin behaviour was monitored both on days when tourist boats were present and on days when they were absent. In the presence of tourists the proportion of time that the dolphins spent resting was reduced by two‐thirds, whereas the times spent milling, travelling, and showing avoidance behaviour all increased.

Furthermore, upon using Markov chain modelling to investigate the effect of tourist presence on the transition probabilities between dolphin activity states, significant changes were found in 10 of the 25 possible behavioural transitions, including increased probabilities of transitioning from resting to milling or travelling, from milling to travelling or avoiding, and from travelling to avoiding.

These findings raise concerns that despite the management measures in place, tourist activities affect the dolphins’ behaviour to a greater extent than was previously apparent, with potential long‐term negative effects on their energy budget. The study led to proposals for amending the zoning of the site and for strengthening the regulations for tourist vessels.
Multiple Vacancies on (111) Facets of Single‐Crystal NiFe2O4 Spinel Boost Electrocatalytic Oxygen Evolution Reaction
Authors: Chen Xiaokang , Zhang Xiaohui , Zhuang Linzhou , Zhang Wei , Zhang Naichi , Liu Hongwei , Zhan Tianrong , Zhang Xiaoli , She Xilin , Yang Dongjiang
Published: June 2020

Oxygen evolution reaction (OER) as the rate‐determining reaction of water splitting has been attracting enormous attention. At present, only some noble−metal oxide materials (IrO2 and RuO2) have been reported as efficient OER electrocatalysts for OER. However, the high cost and scarcity of these noble−metal oxide materials greatly hamper their large−scale practical application. Herein, we synthesize 100% (111) faceted NiFe2O4 single crystals with multiple vacancies (cation vacancies and O vacancies). The (111) facets can supply enough platform to break chemical bonds and enhance electrocatalytic activity, due to its high density of atomic steps and kink atoms. Compared to NiFe2O4 (without vacancies), the as‐synthesized NiFe2O4−Ar (with vacancies) exhibits a dramatically improved OER activity. The NiFe2O4−Ar‐30 shows the lowest onset potential (1.45 V vs RHE) and the best electrocatalytic OER activity with the lowest overpotential of 234 mV at 50 mA cm−2. Furthermore, based on the theoretical calculations that the introduction of multiple vacancies can effectively modulate the electronic structure of active centers to accelerate charge transfer and reaction intermediates adsorption, which can reduce the reaction energy barrier and enhance the activity of electrochemical OER.
In‐air self‐reduction synthesis and colour tunable luminescence from SrBPO5:Eu2+–Eu3+ excited using ultraviolet light
Authors: Wu Yuheng , Wu Yuansheng , Yu Lixin , Zou Yingxuan , Gao Zhenyu , Guo Qihuang , Liu Zongjian , Liu Bingfa
Published: June 2020

SrBPO5:Eu2+–Eu3+ phosphors were synthesized using a conventional solid self‐reduction reaction in an air atmosphere. Samples were characterized using thermogravimetry analysis (TGA), differential scanning calorimetry (DSC), X‐ray diffraction (XRD), Fourier transform infrared (FTIR) spectra, fluorescence spectra and Commission International de l'Eclairage (CIE) data. The results of TGA and DSC showed that the raw materials could completely react at 1000°C. FTIR spectra and XRD results displayed that europium ions of different concentrations do not effect the structure of the hosts. Fluorescence spectra displayed that europium ions exist in bivalent and trivalent forms, and that the emission peak at 403 nm was attributed to the typical 5d−4f transition for Eu2+; 597 nm and 620 nm emissions were assigned to the characteristic transitions of 5D0−7F1, 2 for Eu3+. CIE results depicted that the colour tone of the phosphors could be macro‐controlled from blue to purple by controlling the doping amount of Eu3+.Therefore, relative luminescence intensity between Eu2+ and Eu3+ could be adjusted by controlling the doping concentration of europium to tune the luminescence colour of SrBPO5.
Liquid chromatography tandem mass spectrometry method for determination of fulvestrant in rat plasma and its application to pharmacokinetic studies of a novel fulvestrant microcrystal
Authors: Leng Guangyi , Zuo Yanhua , Hu Jiahui , Yu Fei , Liu Wanhui
Published: June 2020

Fulvestrant (‘Faslodex’), an estrogen receptor antagonist, is available for the treatment of advanced breast cancer. The oil‐based vehicle of Faslodex can lead to various adverse effects. A novel fulvestrant microcrystal (aqueous suspension) was developed in this study to eliminate these adverse effects. A sensitive and robust liquid chromatography tandem mass spectrometry method was developed and validated for the determination of fulvestrant in rat plasma using supported‐liquid extraction. The separation of fulvestrant was achieved on an Agilent SB‐C18column (2.1 × 50 mm, 3.5 μm) with isocratic elution using fulvestrant‐d3 as internal standard. Mass spectrometric detection was conducted in negative multiple reaction monitoring mode. Ion transitions were atm/z605.5 → 427.5 for fulvestrant andm/z608.5 → 430.5 for fulvestrant‐d3. The excellent linearity was demonstrated over the range 0.05–100.0 ng/ml (r2 = 0.99). The lower limit of quantitation was 0.05 ng/ml, which was superior to that reported in literature The method validation was evaluated by selectivity, accuracy, precision, recovery and matrix effect in agreement with the US Food and Drug Administration guidance. The method was successfully applied to a pharmacokinetic study of a novel fulvestrant microcrystal in rats after intramuscular administration. It revealed that the rate of absorption increases and the extent of absorption is constant with a decrease in microcrystal diameter.
Dissociated modulations of multivoxel activation patterns in the ventral and dorsal visual pathways by the temporal dynamics of stimuli
Authors: Li Jiaxin , Guo Bingbing , Cui Lin , Huang Hong , Meng Ming
Published: June 2020

Introduction

Previous studies suggested temporal limitations of visual object identification in the ventral pathway. Moreover, multivoxel pattern analyses (MVPA) of fMRI activation have shown reliable encoding of various object categories including faces and tools in the ventral pathway. By contrast, the dorsal pathway is involved in reaching a target and grasping a tool, and quicker in processing the temporal dynamics of stimulus change. However, little is known about how activation patterns in both pathways may change according to the temporal dynamics of stimulus change.

Methods

Here, we measured fMRI responses of two consecutive stimuli with varying interstimulus intervals (ISIs), and we compared how the two visual pathways respond to the dynamics of stimuli by using MVPA and information‐based searchlight mapping.

Results

We found that the temporal dynamics of stimuli modulate responses of the two visual pathways in opposite directions. Specifically, slower temporal dynamics (longer ISIs) led to greater activity and better MVPA results in the ventral pathway. However, faster temporal dynamics (shorter ISIs) led to greater activity and better MVPA results in the dorsal pathway.

Conclusions

These results are the first to show how temporal dynamics of stimulus change modulated multivoxel fMRI activation pattern change. And such temporal dynamic response function in different ROIs along the two visual pathways may shed lights on understanding functional relationship and organization of these ROIs.
Synthesis, Characterization, Molecular Docking, and Biological Activities of Some Natural and Synthetic Urolithin Analogs
Authors: Noshadi Bahareh , Ercetin Tugba , Luise Chiara , Yuksel Mine Yarim , Sippl Wolfgang , Sahin Mustafa Fethi , Gazi Mustafa , Gulcan Hayrettin Ozan
Published: June 2020

Urolithins (that is, hydroxy substituted benzo[c]chromen‐6‐one derivatives) are formed within the gastrointestinal tract following to the exposure to various ellagitannin rich diet, particularly involving pomegranate, nuts, and berries. Regarding the bioavailability deficiency of ellagitannins, the biological activities obtained through the extracts of these dietaries are attributed to the urolithin compounds, since they are bioavailable. Particularly, there are studies indicating the importance of ellagitannin‐rich food for protective and alternative treatment of Alzheimer's Disease (AD). From this perspective, within this study, the major urolithins (that is, urolithins A and B), their methyl ether metabolites, as well as some synthetic urolithin analogs have been synthesized and screened for their biological activities in various enzyme inhibition (acetylcholinesterase, butyrylcholinesterase, monoamine oxidase B, cyclooxygenase 1, and cyclooxygenase 2) and antioxidant (DPPH radical scavenging) assay systems. The results pointed out the potential of urolithins to act as inhibitors on these receptors. Docking studies were also performed to investigate the possible interactions.
Transcatheter aortic valve replacement in patients with a history of cancer: Periprocedural and long‐term outcomes
Authors: Murphy Alexandra C. , Koshy Anoop N. , Cameron William , Horrigan Mark , Kearney Leighton , Yeo Belinda , Farouque Omar , Yudi Matias B.
Published: June 2020

Background

A history of cancer is incorporated into the surgical risk assessment of patients undergoing surgical aortic valve replacement through the Society for Thoracic Surgeons score. However, the prognostic significance of cancer in patients treated with transcatheter aortic valve replacement (TAVR) is unclear. As the cancer survivorship population increases, it is imperative to establish the efficacy and safety of TAVR in patients with severe symptomatic aortic stenosis (AS) and a history of malignancy.

Objectives

The primary goal of this study was to assess the periprocedural outcomes and long‐term mortality in patients with a history of cancer undergoing TAVR.

Methods

A systematic review of PubMed, MEDLINE, and EMBASE was conducted to identify studies reporting outcomes in patients with a history of malignancy undergoing TAVR. A meta‐analysis was performed using a random‐effects model with a primary outcome of all‐cause mortality and cardiac mortality at the longest follow‐up. On secondary analyses, procedural safety was assessed.

Results

A total of 13 observational studies with 10,916 patients were identified in the systematic review. Seven studies including 6,323 patients were included in the quantitative analysis. Short‐term mortality (relative risk [RR] 0.61, 95%CI 0.36–1.01; p = .06) and long‐term all‐cause mortality (RR 1.24, 95%CI 0.95–1.63; p = .11) were not significantly different when comparing patients with and without a history of cancer. No significant difference in the rate of periprocedural complications including stroke, bleeding, acute kidney injury, and pacemaker implantation was noted.

Conclusion

In patients with severe AS undergoing TAVR, a history of cancer was not associated with adverse short or long‐term survival. Based on these findings, TAVR should be considered in all patients with severe symptomatic AS, irrespective of their history of malignancy.
Signet‐ring cell large B‐cell lymphoma: A potential diagnostic pitfall with signet‐ring cell carcinoma
Authors: Patel Vijay , Pina‐Oviedo Sergio
Published: June 2020

Key Clinical Message

This study reveals the importance of recognizing uncommon histologic variants in diffuse large B‐cell lymphoma, such as the signet‐ring cell variant, which may result in an erroneous or delayed diagnosis with potential impact in patient treatment.