Properties Of Fragments Research Articles

Driving potential and fission-fragment charge distributions

We propose an efficient approach to describe the fission-fragment charge yields for actinides based on the driving potential of the fissioning system. Considering the properties of primary fission fragments at their ground states, the driving potential, which represents the potential energies of the system around scission configuration and closely relates to the yields of fragments, can be unambiguously and quickly obtained from the Skyrme energy-density functional together with the Weizsäcker–Skyrme mass model. The fission-fragment charge distributions for thermal-neutron-induced fission and spontaneous fission of a series of actinides, especially the odd–even staggering in the charge distributions, can be well reproduced. Nuclear dynamical deformations and pairing corrections of fragments play an important role in the charge distributions.

Thermal fragmentation and pulverization behavior of lignite during the vibration drying process and its grey relational analysis of multi-factors

Lignite particles are easy to break into smaller particles in the process of thermal drying, which affect the heat and mass transfer inside the particles. Therefore, it is important to study the fragmentation behavior of lignite for optimizing the drying process. In this article, two concepts of degree of fragmentation (F′) and pulverization ratio (R p ) were put forward to describe the overall fragmentation property of lignite after vibration drying. The results showed that the higher the drying temperature, the more favorable it was for the product particles to fragment. The impact of particle size and feeding amount on F′ and R p was relatively small, but it was still not negligible. There was a critical vibration frequency during vibration drying. Once the vibration frequency exceeded critical value, the fragmentation of particles would be greatly promoted. The grey correlation model of lignite was established to quantitatively analyze the influence of five factors on the fragmentation and pulverization of products in the process of multi-factor coupling drying. Following the grey correlation model, five factors, such as the drying time, vibration frequency, drying temperature, feed particle size and feeding amount were ranked according to their influence on F′ and R p .

Measurements of jet substructure and jet fragmentation using the ATLAS detector

Measurements of the internal properties of jets at the LHC interaction scale allow QCD to be studied in a new energy regime. In this talk, we discuss recent measurements of jet substructure and jet fragmentation, which were performed using data collected by the ATLAS experiment at a centre-of-mass energy of \sqrt{s}=13s=13 TeV. The fragmentation properties of jets, such as the jet charge and summed fragmentation function, are measured using charged particles. A comprehensive suite of jet substructure observables is also measured for jets reconstructed with the soft-drop algorithm applied. In addition, a measurement of the Lund plane is performed using charged particles. All of the measurements are corrected for detector effects and are compared to the predictions of state-of-the-art Monte Carlo event generators.

Characterization of demethylating DNA glycosylase ROS1 from Nicotiana tabacum L.

One of the main mechanisms of epigenetic regulation in higher eukaryotes is based on the methylation of cytosine at the C5 position with the formation of 5-methylcytosine (mC), which is further recognized by regulatory proteins. In mammals, methylation mainly occurs in CG dinucleotides, while in plants it targets CG, CHG, and CHH sequences (H is any base but G). Correct maintenance of the DNA methylation status is based on the balance of methylation, passive demethylation, and active demethylation. While in mammals active demethylation is based on targeted regulated damage to mC in DNA followed by the action of repair enzymes, demethylation in plants is performed by specialized DNA glycosylases that hydrolyze the N-glycosidic bond of mC nucleotides. The genome of the model plant Arabidopsis thaliana encodes four paralogous proteins, two of which, DEMETER (DME) and REPRESSOR OF SILENCING 1 (ROS1), possess 5-methylcytosine-DNA glycosylase activity and are necessary for the regulation of development, response to infections and abiotic stress and silencing of transgenes and mobile elements. Homologues of DME and ROS1 are present in all plant groups; however, outside A. thaliana, they are poorly studied. Here we report the properties of a recombinant fragment of the ROS1 protein from Nicotiana tabacum (NtROS1), which contains all main structural domains required for catalytic activity. Using homologous modeling, we have constructed a structural model of NtROS1, which revealed folding characteristic of DNA glycosylases of the helix– hairpin–helix structural superfamily. The recombinant NtROS1 protein was able to remove mC bases from DNA, and the enzyme activity was barely affected by the methylation status of CG dinucleotides in the opposite strand. The enzyme removed 5-hydroxymethylcytosine (hmC) from DNA with a lower eff iciency, showing minimal activity in the presence of mC in the opposite strand. Expression of the NtROS1 gene in cultured human cells resulted in a global decrease in the level of genomic DNA methylation. In general, it can be said that the NtROS1 protein and other homologues of DME and ROS1 represent a promising scaffold for engineering enzymes to analyze the status of epigenetic methylation and to control gene activity.

Characteristics of Fragments Produced by Ternary Fission in Intermediate Energy

The characteristics of fragments produced in the ternary fissions have been researched by using the improved quantum molecular dynamics model in heavy 197Au+197Au at 15 MeV/nucleon. The physical quantities of Z, n/z, θ, ptrans/plong about the nuclear fragments have strong dependencies on the impact parameters, and their curves are systematically drawn. By the study of these theoretical results above, we have concluded that there is a cut-off point at b =6 fm, which divides the impact parameters into two regions: the central or semi-peripheral and peripheral regions, and the ternary breakup mechanisms should be very different at these two impact parameter regions. Further research has showed that the regional property of n/z is related to the isospin symmetry of nuclear products, and the conclusion reflects the properties of nuclear fragments may be an observable probe into the nucleon interactions during heavy ion collisions.

Design Methods for the Lethality of Fragmentation Warhead based on a Multi-Objective Optimization Algorithm

Abstract Fragmentation warhead is the main weapon used to damage personnel and light armored objectives, with the lethal parameters primarily consisting of the number and velocity of fragments. Increasing the lethality of fragmentation warhead is currently the most important development direction for fragmentation warhead. The formation process of natural fragment is complicated and there are several factors that affect the properties of fragment, so there are still many techniques of developing the lethality of fragmentation warhead. In this paper, our object is to focus on the optimization design for the lethality of fragmentation warhead, based on the optimal Latin hypercube test design method and the radial basis function neural network surrogate modelling, taking the number of effective fragments per unit mass and the average kinetic energy of the effective fragments as the optimization objectives, and the explosive charge, the fragment material, the overall structure and initiation method are considered, respectively. The Pareto optimal solution sets under different design variables are obtained, and the optimal matching of multiple design parameters is realized, establishing the integration design method for “explosive - material-structure” of the fragmentation warhead. The research results can provide technical support for the structural optimization design of the fragmentation warhead.

The RiboMaP Spectral Annotation Method Applied to Various ADP-Ribosylome Studies Including INF-γ-Stimulated Human Cells and Mouse Tissues.

ADP-ribosylation is a post-translational modification that is catalyzed by the ADP-ribosyltransferase enzyme family. Major emphasis to date has been ADP-ribosylation's role in cancer; however, there is growing interest in its role in inflammation and cardiovascular disease. Despite a recent boom in ADP-ribosylation mass spectrometry-based proteomics, there are limited computational resources to evaluate the quality of reported ADP-ribosylated (ADPr) proteins. We recently developed a novel mass spectral annotation strategy (RiboMaP) that facilitates identification and reporting of ADPr peptides and proteins. This strategy can monitor the fragmentation properties of ADPr peptide-unique fragment ions, termed m-ions and p-ions, that in turn provide spectral quality scores for candidate ADP-ribosyl peptides. In this study, we leveraged the availability of publicly available ADP-ribosylome data, acquired on various mass spectrometers, to evaluate the broader applicability of RiboMaP. We observed that fragmentation spectra of ADPr peptides vary considerably across datasets; nonetheless, RiboMaP improves ADPr peptide spectral annotation across all studies. We then reanalyzed our own previously published in vitro ADP-ribosylome data to determine common responses to the pro-inflammatory cytokine, IFN-γ. We conclude that despite these recent advances in the field of ADPr proteomics, studies in the context of inflammation and cardiovascular disease still require further bench-to-informatics workflow development in order to capture ADPr signaling events related to inflammatory pathways.

Clickable report tags for identification of modified peptides by mass spectrometry.

The identification and quantification of modified peptides are critical for the functional characterization of post-translational protein modifications (PTMs) to elucidate their biological function. Nowadays, quantitative mass spectrometry coupled with various bioinformatic pipelines has been successfully used for the determination of a wide range of PTMs. However, direct characterization of low abundant protein PTMs in bottom-up proteomic workflow remains challenging. Here, we present the synthesis and evaluation of tandem mass spectrometry tags (TMT) which are introduced via click-chemistry into peptides bearing alkyne handles. The fragmentation properties of the two mass tags were validated and used for screening in a model system and analysis of AMPylated proteins. The presented tags provide a valuable tool for diagnostic peak generation to increase confidence in the identification of modified peptides and potentially for direct peptide-PTM quantification from various experimental conditions.

DFT study of the influence of boron/nitrogen substitution on the electronic and nonlinear optical properties of the benzene-substituted graphdiyne fragment

A series of B/N-substituted benzene-substituted graphdiyne fragments (1) were studied in detail by density functional theory to evaluate their electronic structures and nonlinear optical (NLO) properties. Substituting a B (N) atom for a C atom introduces extra holes (electrons) in the electronic structure of the compound. The introduction of the N atom can effectively narrow the large energy gap of the 1, but the value for the B-substituted system does not change significantly. Such compounds show superior NLO response with respect to pristine 1, and the static first hyperpolarizability (β0) values of most of N-substituted compounds are larger than the corresponding B-substituted compounds. Moreover, the result of static β0 of the system can be deeply understood by the distribution of first hyperpolarizability density. These fascinating findings can provide valuable insights for the development of potential high-performance NLO nanomaterials.

Fragmented Property Rights and Residents’ Participation in Renovation of Old Communities: Comparative Case Studies in Haikou, China

Insufficient residents’ participation in the renovation of old communities is ubiquitous in urban China. This paper attempts to explain the reasons for this phenomenon. Based on the theory of anti-commons, this research intends to explore how the fragmentation of property rights impedes residents’ participation, and then unravel the mechanism of conflicts and cooperation among various stakeholders in renovation projects. Abundant qualitative data in terms of the situation of property rights were collected by semi-structured interviews from fieldwork on seven renovation projects in Haikou, Hainan Province, China. Then we compared the seven projects to examine the relationship between property rights and resident’s participation. This study shows that characteristics of residents’ participation vary from types of property rights in the renovation of old communities. Residents’ participation can be facilitated by the privatization of property rights, but fragmented property rights tend to impede participation. Meanwhile, administrative obstacles between street offices, residents’ committees, and homeowners’ associations will ebb residents’ motivation for participation. Yet the homeowners’ association plays an important role in dispute handling, which can promote residents’ involvement.

Prion Protein: The Molecule of Many Forms and Faces.

Cellular prion protein (PrPC) is a glycosylphosphatidylinositol (GPI)-anchored protein most abundantly found in the outer membrane of neurons. Due to structural characteristics (a flexible tail and structured core), PrPC interacts with a wide range of partners. Although PrPC has been proposed to be involved in many physiological functions, only peripheral nerve myelination homeostasis has been confirmed as a bona fide function thus far. PrPC misfolding causes prion diseases and PrPC has been shown to mediate β-rich oligomer-induced neurotoxicity in Alzheimer’s and Parkinson’s disease as well as neuroprotection in ischemia. Upon proteolytic cleavage, PrPC is transformed into released and attached forms of PrP that can, depending on the contained structural characteristics of PrPC, display protective or toxic properties. In this review, we will outline prion protein and prion protein fragment properties as well as overview their involvement with interacting partners and signal pathways in myelination, neuroprotection and neurodegenerative diseases.

Homeowners’ Associations as Urban Property Management Entities

The concept “homeowners’ association” falls within the description of fragmented property schemes. It is an entity that is the owner or manager of communal property and the land of an estate, consisting of individual properties owned by members of the association and communal areas used collectively by the individual owners. The individual properties and communal areas are managed in terms of conditions and rules, albeit with different purposes. A homeowners’ association is normally a juristic person incorporated as a non-profit company or by agreement between the individual owners as members to establish a common law juristic person. In terms of its management documents, it has the capacity to manage the estate and enforce the rules of the scheme. Therefore, the memorandum or constitution should contain specific management directions, which are discussed in this article. The rules of the scheme must be approved by the Ombud for Community Schemes before they may be enforced. The latter may also be approached to mediate disputes between members of the association or between members and the management. Initially the social-political need for urban fragmented property schemes is explained, followed by an analysis of the management of urban fragmented property. It is emphasised that ownership of immovable property is not only an individual right, but also fulfils an important community function. The legalities surrounding the establishment of a homeowners’ association is thereafter discussed. Essential matters to be included in the management documents are examined with specific reference to the enforceability and constitutionality of the rules of the association. Finally, the establishment of gated communities is reviewed with an emphasis on the constitutional viability of imposing limitations on the fundamental rights of owners, occupiers and third parties (like visitors and employees) who need access to the scheme or want to use communal areas in the scheme.

Spectral and proton acceptor properties of chloramphenicol

The absorption spectra of chloramphenicol aqueous solution were obtained experimentally. The absorption spectra of chloramphenicol isomers and the effect on the spectra of the formation of H-bonded complexes were calculated and interpreted using quantum chemistry methods. Calculation results showed that the absorption spectrum of chloramphenicol by position of bands and their nature is largely determined by the nitrobenzene fragment with little participation of propanol and dichloroacetamide fragments of chloramphenicol. The proton acceptor properties of individual chloramphenicol fragments and the effect of the formation of H-bonded complexes on them have been analyzed. Keywords: chloramphenicol, enantiomers, electronic absorption spectrum.

Спектральные и протоноакцепторные свойства хлорамфеникола

The absorption spectra of chloramphenicol aqueous solution were obtained experimentally. The absorption spectra of chloramphenicol isomers and the effect on the spectra of the formation of H-bonded complexes were calculated and interpreted using quantum chemistry methods. Calculation results showed that the absorption spectrum of chloramphenicol by position of bands and their nature is largely determined by the nitrobenzene fragment with little participation of propanol and dichloroacetamide fragments of chloramphenicol. The proton acceptor properties of individual chloramphenicol fragments and the effect of the formation of H-bonded complexes on them have been analyzed.

W51 North: A protocluster emerging out of a thermally inhibited fragmenting cloud

Context. The fragmentation process in massive star-forming regions is one of the contemporary problems in astrophysics, and several physical processes have been proposed to control the fragmentation including turbulence, magnetic field, rotation, stellar feedback, and gravity. However, the fragmentation process has been poorly studied at small spatial scales well below 1000 AU. Aims. W51 IRS2 is a well-known massive star-forming region whose fragmentation properties have not been thoroughly investigated yet. We aim to use the Atacama Large Millimeter and Submillimeter Array (ALMA) high angular resolution data to identify the fragments in W51 IRS2 and to study the fragmentation properties on a spatial scale of 0.04′′ (200 AU). Methods. We used ALMA data of W51 IRS2 from three projects, which give an angular resolution of 0.028′′ (144 AU) at millimeter wavelengths. The continuum images reveal a significant substructure in an east-west ridge, where both W51 North and W51d2 are embedded. A spectral index map has been generated from the 3 and 1.3 mm high-resolution continuum images. We identified compact fragments by using uv-range constrained 1.3 mm continuum data. A mean surface density of companions (MSDC) analysis has been performed to study the separations between fragments. Results. A total number of 33 continuum sources are identified and 29 out of them are defined as fragments in the surveyed region.The MSDC analysis reveals two breaks corresponding to spatial scales of 1845 and 7346 AU, indicative of a two-level clustering phenomenon, along with a linear regime below 1845 AU, mostly associated with W51 North, whose slope is consistent with the slope for the clustering regime of other cluster-like regions in the Galaxy. Conclusions. The typical masses and separations of the fragments as well as the relation between the density and number of fragments can be explained through a thermal Jeans process operating at high temperatures of 200–400 K, consistent with previous measurements of the temperature in the region, and produced by the nearby massive stars. Therefore, although W51 IRS2 seems to be undergoing a thermally inhibited fragmentation phase, this does not seem to prevent the formation of a protocluster associated with W51 North.

Fragment-to-Lead Medicinal Chemistry Publications in 2020.

Fragment-based drug discovery (FBDD) continues to evolve and make an impact in the pharmaceutical sciences. We summarize successful fragment-to-lead studies that were published in 2020. Having systematically analyzed annual scientific outputs since 2015, we discuss trends and best practices in terms of fragment libraries, target proteins, screening technologies, hit-optimization strategies, and the properties of hit fragments and the leads resulting from them. As well as the tabulated Fragment-to-Lead (F2L) programs, our 2020 literature review identifies several trends and innovations that promise to further increase the success of FBDD. These include developing structurally novel screening fragments, improving fragment-screening technologies, using new computer-aided design and virtual screening approaches, and combining FBDD with other innovative drug-discovery technologies.

Demand Aggregation as a Strategy for Untapping Buildings’ Energy Renovation Potential: Diagnosis and Prioritization Methodology and Case Study from the Basque Country

Energy renovation of post-World War II private multifamily residential buildings has been identified to have a great deal of energy-saving potential but faces a great challenge across Europe, and especially in South Europe, due to fragmented property structures and longer return periods in energy efficiency investments. However, there is great deal of potential in activating demand aggregation in areas with homogeneous typologies. Local authorities play a key role in leading district-scale renovation but lack adequate methods for analysing and prioritizing areas from an integrated perspective, including social aspects. The methodology presented in this paper aims to support local authorities by providing a tool for the diagnosis and prioritization of homogeneous groups of residential buildings to address their renovation based on an analysis of their needs and opportunity factors. First, the methodology sets the universe of analysis; second, based on indicators, it provides comparative information within the municipality, which leads to a prioritization of areas for building renovations according to the state of the building and to the socio-economic profile of the residents; lastly, a detailed diagnosis of selected groups is performed, providing information to design the Renovation Action Plans accordingly. The application of the methodology in Basauri is presented in this paper.

An extensive study of depth dose distribution and projectile fragmentation cross-section for shielding materials using Geant4

Geant4 Monte Carlo simulation was executed for 16O beam in various elemental and hydrogenous materials for assessment of ion characteristics and shielding efficacy. In the energy-dependent comparison, at energies 200–594 MeV/n, the peak to entrance ratio decrement up to 78.6% in water target validates the substantial increase in fragmentation factor. Further, hydrogenous materials and low Z elements (C, Al) demonstrate a low peak-to-entrance ratio (0.92–1.66) compared to heavy element (Cu, Sn, Pb) ratio (2.73–3.54), at 594 MeV/n, indicating the high fragmentation properties of hydrogenous and low Z elements. Accordingly, the depth dose reduction percentage was found to be significantly higher for hydrogenous materials (0.92–1.72%) having 4.20–14.37 H wt.% than non-hydrogenous targets (0.09–0.82%). LiH was found to exhibit the lowest peak-to-entrance ratio and highest depth dose reduction. The high shielding effectiveness of LiH (12.59%) irrespective of having a low H fraction compared to polyethylene (14.37%) which is widely used shielding material, suggests the contribution of low Z element Li (87.41 wt%) over the C (85.63 wt%) element in the material. Also, simulated results of fragmentation for high Z materials were compared with the experimental data for the reliability of Geant4. Finally, the comparison of these properties recommends the use of hydrogenous materials with low Z elements for effective space radiation shielding.

Exploring the sequence space of unknown oligomers and polymers

The characterization of the chemistry of life on earth has been facilitated by developments in analysis and sequencing of bio-oligomers using tandem mass spectrometry (MS/MS). Bio-oligomers can be identified with sequence-level resolution in analytes more complex than any synthetic mixture, enabled by well-established knowledge of fragmentation properties and extensive MS/MS databases built up over decades. However, unknown oligomer systems remain difficult to characterize, as no comparable databases exist, partly because of the vast chemical diversity and fragmentation pathways. Here, we present oligomer-soup-sequencing (OLIGOSS), a new approach to the sequencing of unknown oligomer systems. Using a novel set of backbone-agnostic abstract properties to define fragmentation, OLIGOSS is capable of sequencing any linear oligomer class amenable to MS/MS, regardless of backbone chemistry. We validated OLIGOSS by sequencing synthetic peptides, polyesters, polyimines and depsipeptide oligomers, mapped RNA methylation sites, and a ribosomally synthesized peptide, thioholgamide, directly from a cell lysate without purification. New approach to the sequencing of unknown oligomer systems Sequencing for any linear oligomer classes amenable to MS/MS Validation using synthetic peptides, polyesters, polyimines, and depsipeptide oligomers Used to map RNA methylation sites and sequence a ribosomally synthesized thioholgamide Doran et al. present oligomer-soup-sequencing (OLIGOSS), which offers an approach to the sequencing of unknown oligomer systems. Using a set of backbone-agnostic abstract properties to define fragmentation, OLIGOSS is capable of sequencing any linear oligomer class amenable to MS/MS, regardless of backbone chemistry.

Measurement of b-quark fragmentation properties in jets using the decay B\xb1\u2192 J/\u03c8K\xb1 in pp collisions at sqrt{s} = 13 TeV with the ATLAS detector

The fragmentation properties of jets containing b-hadrons are studied using charged B mesons in 139 fb−1 of pp collisions at sqrt{s} = 13 TeV, recorded with the ATLAS detector at the LHC during the period from 2015 to 2018. The B mesons are reconstructed using the decay of B± into J/ψK±, with the J/ψ decaying into a pair of muons. Jets are reconstructed using the anti-kt algorithm with radius parameter R = 0.4. The measurement determines the longitudinal and transverse momentum profiles of the reconstructed B hadrons with respect to the axes of the jets to which they are geometrically associated. These distributions are measured in intervals of the jet transverse momentum, ranging from 50 GeV to above 100 GeV. The results are corrected for detector effects and compared with several Monte Carlo predictions using different parton shower and hadronisation models. The results for the longitudinal and transverse profiles provide useful inputs to improve the description of heavy-flavour fragmentation in jets.