Kinds Of Hosts Research Articles

Theoretical Insights into the Photophysical Properties of 4CzIPN Doped in Different Hosts: A Multiscale Study.

As a typical thermally activated delayed fluorescence (TADF) emitter with green emission, 4CzIPN has attracted much attention recently. Most studies indicated that 4CzIPN doped in different hosts presented different performances; thus, the hosts should have an obvious influence on its photophysical properties. Herein, the influence of four kinds of hosts, including m-CzPym, m-CzTrz, p-CzPym, and p-CzTrz, on the photophysical properties of 4CzIPN is investigated. Molecular dynamics simulations were performed to simulate the host-guest conformations, and the photophysical properties were studied using the combined quantum mechanics/molecular mechanics method coupled with the thermal-vibration correlation function method. It is found that 4CzIPN in doped films has larger transition dipole moments and spin-orbital coupling constants compared to that in nondoped films. Faster radiative decay, intersystem crossing rates, and higher fluorescence efficiency could be obtained in doped films. Our work helps to better understand the photophysical properties of 4CzIPN in doped films and may favor the design of new hosts.

Recent Advances in Multi-Site Luminescent Materials: Design, Identification and Regulation

The development of novel phosphor materials with excellent performance and modification of their photoluminescence to meet the higher requirements for applications are the essential research subjects for luminescent materials. Multi-site luminescent materials with crystallographic sites for the activator ions that broaden the tunable range of luminescent spectra and even enhance the luminescent performance have attracted significant attention in the pursuit of high-quality luminescence for white light-emitting diodes. Here, we summarize multi-site luminescence characteristics based on the different kinds of host and activator ions, introduce the identifications of multi-site activator ions via optical analysis, provide a structural analysis and theoretical calculation methods, and introduce the regulation strategies and advance applications of multi-site phosphors. The review reveals the relationship between crystal structure and luminescent properties and discusses future opportunities for multi-site phosphors. This will provide guidance for the design and development of luminescent materials or other materials science.

Diversity of RNA viruses of three dominant tick species in North China.

A wide range of bacterial pathogens have been identified in ticks, yet the diversity of viruses in ticks is largely unexplored. Here, we used metagenomic sequencing to characterize the diverse viromes in three principal tick species associated with pathogens, Haemaphysalis concinna, Dermacentor silvarum, and Ixodes persulcatus, in North China. A total of 28 RNA viruses were identified and belonged to more than 12 viral families, including single-stranded positive-sense RNA viruses (Flaviviridae, Picornaviridae, Luteoviridae, Solemoviridae, and Tetraviridae), negative-sense RNA viruses (Mononegavirales, Bunyavirales, and others) and double-stranded RNA viruses (Totiviridae and Partitiviridae). Of these, Dermacentor pestivirus-likevirus, Chimay-like rhabdovirus, taiga tick nigecruvirus, and Mukawa virus are presented as novel viral species, while Nuomin virus, Scapularis ixovirus, Sara tick-borne phlebovirus, Tacheng uukuvirus, and Beiji orthonairovirus had been established as human pathogens with undetermined natural circulation and pathogenicity. Other viruses include Norway mononegavirus 1, Jilin partitivirus, tick-borne tetravirus, Pico-like virus, Luteo-like virus 2, Luteo-likevirus 3, Vovk virus, Levivirus, Toti-like virus, and Solemo-like virus as well as others with unknown pathogenicity to humans and wild animals. In conclusion, extensive virus diversity frequently occurs in Mononegavirales and Bunyavirales among the three tick species. Comparatively, I. persulcatus ticks had been demonstrated as such a kind of host with a significantly higher diversity of viral species than those of H. concinna and D. silvarum ticks. Our analysis supported that ticks are reservoirs for a wide range of viruses and suggested that the discovery and characterization of tick-borne viruses would have implications for viral taxonomy and provide insights into tick-transmitted viral zoonotic diseases.

Divas on the Dance Floor

Divas on the Dance Floor

(Invited) Detailed Analysis of Highly-Efficient Emission in Organic Light-Emitting Diodes: The Dynamic Exciton Effect

Thermally activated delayed fluorescence (TADF) is an excellent way to convert originally dark triplet excitons into light.1 To realize the conversion, minimization of the energy gap between S1 and T1, called ΔE ST, has been effective.1,2 Actually, reverse intersystem crossing (RISC) becomes possible by the small ΔE ST.1-4 However, the rate constant of RISC (k RISC) is relatively small compared to those of competing processes, such as radiative and non-radiative decays, resulting that RISC is the rate-limiting process in TADF systems. Therefore, the acceleration of RISC is a key factor to obtain further excellent TADF-based organic light-emitting diodes (OLEDs).The small k RISC originates from small spin-orbit coupling (SOC). The S1 and T1 of TADF molecules tend to have charge transfer (CT) character, because the HOMO and LUMO are well-separated to make the ΔE ST small. The intersystem crossing (ISC) and RISC between CT-type S1 (1CT) and CT-type T1 (3CT) are spin-forbidden.5 This problem can be solved by intervening locally excited (LE) state(s) between 1CT and 3CT. Recently, we successfully achieved very fast RISC with a k RISC exceeding 107 s-1 by a new material design concept, named “tilted face-to-face alignment with optimal distance” (tFFO)6-8 by realizing the excellent energy level matching of 1CT, 3CT, and 3LE with sufficient SOC between 1CT and 3LE.In the presentation, I will first talk about detailed analysis of a TADF molecule, MA-TA.8-10 The performance is very high; the experimentally-obtained photoluminescence quantum yield (PLQY) and maximum external quantum efficiency (EQE) were 100% and 23.9%, respectively. The results seem to be contradictory to the above, because donor and acceptor (D-A) segments are perpendicular with each other resulting that both the S1 and T1 are CT-type, and higher-lying 3LE states cannot participate in the RISC process. Also, highly PLQY of 100% cannot be expected from the perpendicular structure. Our detailed quantum chemical analysis revealed that the dynamic or static D-A fluctuation was the key trigger of both the fast RISC and high PLQY. Such direct 3CT→1CT RISC-based OLEDs without using any 3LEs have an advantage that various kinds of hosts having different polarities can be used without sacrificing the device performance, that is, high EQE and blue-shifted emission can be realized simultaneously.Secondly, I will talk about the development of a high-throughput material screening method by quantitatively predicting rate constants of all relevant electronic transitions. TADF molecules have been designed through the calculations of ΔE ST and oscillator strength to realize effective RISC and following radiative decay simultaneously. However, in addition to ΔE ST, SOC is also another key factor to control k RISC as described above. Not only radiative but also non-radiative decays should be considered to obtain high PLQYs. We here propose a new method to predict TADF performance more precisely.11 Our method based on the Fermi golden rule enables us to theoretically predict relevant rate constants for all types of electronic transitions in an emitter molecule with reasonable computational cost. We applied the method to benzophenone; the calculated rate constants quantitatively agreed with the experimental ones. We are now extending this method to various TADF molecules and singlet fission systems.12-14 We express sincere thanks to my group members. This work was supported by JSPS KAKENHI Grant Numbers JP20H05840 (Grant-in-Aid for Transformative Research Areas, “Dynamic Exciton”). Computation time and NMR measurements were supported by the international Joint Usage/Research Centre at the Institute for Chemical Research, Kyoto University, Japan.1 H. Uoyama, K. Goushi, K. Shizu, H. Nomura & C. Adachi Nature 492, 234 (2012).2 H. Kaji et al. Nat. Commun. 6, 8476 (2015).3 Z. Yang et al. Chem. Soc. Rev. 46, 915 (2017).4 M. Y. Wong & E. Zysman-Colman Adv. Mater. 29, 1605444 (2017).5 M. A. El-Sayed J. Chem. Phys. 38, 2834 (1963).6 Y. Wada, H. Nakagawa, S. Matsumoto, Y. Wakisaka & H. Kaji Nat. Photon. 14, 643 (2020).7 Y. Kusakabe, Y. Wada, H. Nakagawa, K. Shizu & H. Kaji Front. Chem. 8, 530 (2020).8 H. Imahori, Y. Kobori & H. Kaji Acc. Chem. Res. 2, 501 (2021).9 Y. Wada, Y. Wakisaka & H. Kaji ChemPhysChem 22, 625 (2021).10 Y. Wada, K. Shizu & H. Kaji J. Phys. Chem. A 125, 4534 (2021).11 K. Shizu & H. Kaji J. Phys. Chem. A 125, 9000 (2021).12 K. Shizu, C. Adachi & H. Kaji J. Phys. Chem. A 124, 3641 (2020).13 K. Shizu, C. Adachi & H. Kaji Bull. Chem. Soc. Jpn. 93, 1305 (2020).14 K. Shizu, C. Adachi & H. Kaji ACS Omega 6, 2638 (2021).

A novel design of 3D carbon host for stable lithium metal anode

AbstractRational design of porous conductive hosts with high electrical conductivity, large surface area, and adequate interior space is desirable to suppressing dendritic lithium growth and accommodating large volume change of lithium metal anode during the Li plating/stripping process. However, due to the conductive nature of the conductive hosts, Li is easily deposited directly on the top of the hosts, which hinders it from fully functioning. To circumvent the issue, in this study, we designed a novel porous carbon host with a gradient‐pore‐size structure based on one‐dimensional (1D) carbon with different diameters. With this kind of host, stable cycling with high and stable Coulombic efficiency of ~98% is achieved at 0.5 mA cm−2 with an areal capacity of 1 mAh cm−2 over 320 cycles. In contrast, the normal three‐dimensional (3D) carbon nanotube host presents a moss‐like Li morphology with wildly fluctuating Coulombic efficiency after 100 cycles. The results reveal that the unique gradient‐pore‐size structure of the 3D conductive host greatly improves the performance of lithium metal batteries.

Regulation of DNA methylation on key parasitism genes of Cysticercus cellulosae revealed by integrative epigenomic-transcriptomic analyses

BackgroundThe life cycle of Taenia solium is characterized by different stages of development, requiring various kinds of hosts that can appropriately harbor the eggs (proglottids), the oncospheres, the larvae and the adults. Similar to other metazoan pathogens, T. solium undergoes transcriptional and developmental regulation via epigenetics during its complex lifecycle and host interactions.ResultIn the present study, we integrated whole-genome bisulfite sequencing and RNA-seq technologies to characterize the genome-wide DNA methylation and its effect on transcription of Cysticercus cellulosae of T. solium. We confirm that the T. solium genome in the cysticercus stage is epigenetically modified by DNA methylation in a pattern similar to that of other invertebrate genomes, i.e., sparsely or moderately methylated. We also observed an enrichment of non-CpG methylation in defined genetic elements of the T. solium genome. Furthermore, an integrative analysis of both the transcriptome and the DNA methylome indicated a strong correlation between these two datasets, suggesting that gene expression might be tightly regulated by DNA methylation. Importantly, our data suggested that DNA methylation might play an important role in repressing key parasitism-related genes, including genes encoding excretion-secretion proteins, thereby raising the possibility of targeting DNA methylation processes as a useful strategy in therapeutics of cysticercosis.

Efficient Direct Reverse Intersystem Crossing between Charge Transfer-Type Singlet and Triplet States in a Purely Organic Molecule.

The front cover artwork is provided by the group of Prof. Hironori Kaji, Dr. Yoshimasa Wada, and Mr. Yasuaki Wakisaka (Institute for Chemical Research, Kyoto University). The image shows our designed emitter molecule, MA-TA, possessing charge-transfer (CT) character in both triplet and singlet states. The dynamic flexibility of molecules allows effective reverse intersystem crossing (RISC) and MA-TA show excellent performances in any kinds of hosts. Read the full text of the Article at 10.1002/cphc.202001013.

Saccharide Recognition by a Three-Arm-Shaped Host Having Preorganized Three-Dimensional Hydrogen-Bonding Sites.

Generally, cage-shaped hosts for saccharides can bind strongly to guest molecules because of the three-dimensional preorganized hydrogen-bonding sites. However, the preparation of cage molecules is often difficult because of the low yield of the macrocyclization step. Here, we report a three-arm-shaped molecule possessing pyridine-acetylene-phenol units as a new kind of host having a preorganized three-dimensional hydrogen-bonding site. This three-arm-shaped host was readily prepared compared to a cage-shaped analogue. This host associated with lipophilic glycosides to form chiral complexes, and the association constants were sufficiently high as to be comparable to those of the cage-shaped analogue. Furthermore, this host extracted native monosaccharides into a lipophilic solvent.

Excavata-Kinetoplastea Trypanosomatidae Parasites and the Interaction with their Hosts

Kinetoplastea Trypanosomatidae are unicellular flagellated parasites of different kind of hosts. They cause diseases in plants, animals and humans. These parasites are transmitted by insect vectors in a wide range of geographic areas. In this communication we review the interactions between trypanosomatid parasites, their hosts and thoughts about their impact on environmental health, especially in those regions where hosts are natural reserves of many species.

Do Airbnb’s “Superhosts” deserve the badge? An empirical study from China

ABSTRACTThe “Superhost” badge is that Airbnb entitles the host provides good services. This study verifies Airbnb’s “Superhost” mechanism by applying text mining technologies, combined with Long Short-Term Memory (LSTM) and K-Means, to the entire dataset of tourists’ online reviews of Hangzhou city, China. Six kinds of hosts’ good services are identified, including “Three Meals or Night Snacks,” “Fruits, Drinks or Snacks,” “Travel Guides,” “Free Shuttle or Helping with Luggage,” “Chats,” and “Replies or Communications.” The study reveals the minority of “Superhosts” are mentioned of providing the majority of six kinds of good services, which means “Superhosts” do deserve the badge.

Iinfectious hypodermal and haematopoietic necrosis virus (IHHNV) infection in freshwater crayfish Procambarus clarkii

Infectious hypodermal and haematopoietic necrosis virus (IHHNV) is a major viral pathogen in cultured penaeid shrimp. IHHNV has many kinds of hosts, especially those in crustacean. Freshwater crayfish Procambarus clarkii is one of widespread crustaceans, which can be infected by several penaeid shrimp viruses. However, it is still unknown whether P. clarkii is susceptible to IHHNV infection. In this study, IHHNV positive samples were found in wild P. clarkii samples. In IHHNV injection experiment, 100% of P. clarkii samples showed IHHNV positive and enlarged nuclei could be observed in P. clarkii gill sections. These results suggested that P. clarkii could be infected by IHHNV both naturally and experimentally. Statement of relevanceThe freshwater crayfish P. clarkii could be infected by IHHNV naturally and experimentally. P. clarkii imposes the potential risk of transmitting IHHNV to penaeid shrimp.

Effect of the epidemiological heterogeneity on the outbreak outcomes.

Multi-host pathogens infect and are transmitted by different kinds of hosts and, therefore, the host heterogeneity may have a great impact on the outbreak outcome of the system. This paper deals with the following problem: consider the system of interacting and mixed populations of hosts epidemiologically different, what would be the outbreak outcome for each host population composing the system as a result of mixing in comparison to the situation with zero mixing? To address this issue we have characterized the epidemic response function for a single-host population and defined a heterogeneity index measuring how host systems are epidemiologically different in terms of generation time, basic reproduction number R0 and, therefore, epidemic response function. Based on the individual epidemiological characteristics of populations, with heterogeneities and mixing affinities, the response of subpopulations in a multi-host system is compared to that of a single-host system. The case of a two-host system, in which the infection transmission depends solely on the infection susceptibility of the receiver, is analyzed in detail. Three types of responses are observed: dilution, amplification or no effect, corresponding to lower, higher or equal attack rates, respectively, for a host population in an interacting multi-host system compared to the zero-mixing situation. We find that no effect is generally observed for zero heterogeneity. A dilution effect is always observed for all the host populations when their individual R0,i < 1. Whereas, when at least one of the individual R0,i > 1, then the hosts ''i'' with R0,i > R0,j undergo a dilution effect while the hosts ''j'' undergo an amplification effect.

Cultural and behavioral differences: tour guides gazing at tourists

ABSTRACTThe aim of this exploratory study is to describe, examine, and analyze the manner in which tour guides in Israel gaze at the groups of foreign tourists they lead, in light of their close familiarity and cumulative experience with them. How do Israeli tour guides view different types of tourists, tourist behaviors, and tourist worldviews? The concept of ‘gaze’ refers to the manner in which people view the world around them. When a gaze is focused, it may include both visual and nonvisual elements. The study methodology is based on a grounded theory approach and on in-depth interviews with Israeli tour guides regarding their attitudes toward and perceptions and images of the tourists in their groups. The study proposes a model of five complementary gazes that develop over time, which depicts the processes and elements that help shape how hosts understand the tourists with whom they come in contact. Although the model was based on findings generated by interviews with Israeli tour guides, who are professional hosts, it may also be applicable to other kinds of hosts in different contexts.

Efficient modulation of optical and electrical properties of X-shaped thermally activated delayed fluorescence emitters by substitution.

A series of X-shaped thermally activated delayed fluorescence (TADF) emitters are systematically studied by first-principles calculations. Effects of the cyano group adding to the acceptor unit and the hydroxyl group adding to the donor part on the optical and electrical properties are analyzed. It is found that both kinds of groups can efficiently increase the emission wavelength to realize full-color emission. Although they play different roles in modulating the energy level of frontier orbitals, the S-T energy gap, the reorganization energy and transfer integral for different molecules, they can efficiently increase the charge transfer rate and reduce the difference of electron transfer rate and hole transfer rate. These results indicate that these designed strategies are efficient to achieve balanced charge transfer rates and modulate emission colors. By analyzing the energy matching between the TADF emitters and three kinds of hosts, the emission spectra of the 3,5-bis(N-carbazolyl)benzene (mcp) and the absorption spectra of most TADF emitters have a large overlap, which provides helpful information in application of these TADF molecules.

Identification and characterization of immunodominant linear epitopes on the antigenic region of a serine protease in newborn Trichinella larvae.

An immunodominant serine protease of Trichinella spiralis named NBL1 showed encouraging potential in early diagnosis of trichinellosis in pigs and elicited protective immune responses during infection of animals. To further define serological reagents for diagnostic use, the specific epitopes on NBL protein recognized by the antibody responses of different susceptible hosts need to be defined. The present study described comprehensive mapping of immunodominant linear epitopes in the antigenic region (NBL-C, the C-terminal part of the protein) using various serum samples obtained from three kinds of hosts - pig, wild boar and mice. We identified six peptides which were commonly recognized by sera from pigs experimentally infected with Trichinella and pigs immunized with rNBL1-C; five and four peptides were recognized by sera from wild boars and mice infected with Trichinella, respectively. Three peptides (NBL1-6, -7 and -9) were commonly recognized by antisera in all three hosts, which share the sequence PSSGSRPTYP. We also found that one peptide (NBL1-12) was only recognized by antibodies from pigs immunized with rNBL1-C. The identification of specific epitopes targeted by the host antibody response is important both for understanding the natural response to infection and for the development of subunit vaccines and diagnostic tools for trichinellosis.

Upconversion emission properties and tunable morphologies of Y6WO12:Yb3+/Er3+ phosphor

Yb3+/Er3+ co-doped Y6WO12 phosphors are prepared by hydrothermal method and subsequently calcination. According to tuning the EDTA usage, the phosphors present four morphologies (cylinder, short-cylinder, flower-like and triangle shape). It is found that the usage of EDTA play crucial role in the formation of morphology. Based on the DSC-TG curves, the pure Y6WO12 are obtained by annealing the precursors at a wide range of temperatures. After annealing, strong red emissions and weak green emissions are observed under 980nm excitation, which is different from the uncalcined products (green emissions are stronger than red emissions). Then we studied the changing tendency of the upconversion (UC) luminescence properties of the calcined and uncalcined products. At last, the pumping power on the UC luminescence properties and the level diagram mechanism of Y6WO12:Yb3+/Er3+ phosphor have also been discussed. We think this work may have the guiding function for obtaining different morphologies by adjusting EDTA and provide new channel of changing the green to red ratio in these kinds of host.

Aluminate matrix doped with Tm3+/Tb3+/Eu3+ obtained by non-hydrolytic sol–gel route: White light emission

RGB represents the union of the colors red (R), green (G), and blue (B), the colors that are most often used in electronic displays. Several kinds of host can serve as phosphors, but the appropriate amount of dopant in tricolor white light with excitation at the same wavelength remains an issue. We used yttrium aluminum garnet (YAG) as host for the lanthanides europium, terbium, and thulium. We prepared the YAG host by the non-hydrolytic sol–gel methodology and doped it with the same amount of lanthanide ions − 1% in relation to the amount of yttrium. We have already reported the characterization of this sample previously. Here, we aimed to investigate the emission spectrum of the sample in the red, green, and blue regions when excited at a certain wavelength. The x and y coordination chromaticity − x=0.32 and y=0.35 − presented values close to those of the white color (x=y=0.33). In conclusion, the YAG host doped with lanthanides and prepared by the sol–gel methodology will help prepare efficient phosphors for several applications.

Study of Hole-Injecting Properties in Efficient, Stable, and Simplified Phosphorescent Organic Light-Emitting Diodes by Impedance Spectroscopy

Simplified phosphorescent organic light-emitting diodes (OLEDs) using only two kinds of hosts and comprising either a neat MoO(x) hole-injecting layer (HIL) or a MoO(x)-doped 4,4'-bis(carbazol-9-yl)biphenyl (CBP) HIL were studied. The devices having the MoO(x)-doped CBP HIL are superior to the device having the neat MoO(x) HIL in terms of power efficiency and operational lifetime. Impedance spectroscopy studies revealed that both the reduced hole-injecting barrier height at the anode/doped HIL interface and the reduced bulk resistivity in the doped CBP HIL contribute to the improvement in electroluminescence characteristics. When increasing the MoO(x) volume percentage from 5 to 10% and then to 20%, the hole-injecting barrier height is decreased from 0.63 eV to 0.36 eV and then to 0.18 eV. The power efficiency of the device with a 20 vol % of MoO(x)-doped CBP HIL is more than two times that of the device with a neat MoO(x) HIL measured at a driven current of 5 mA/cm(2). Moreover, the lifetime of the device with a 20 vol % of MoO(x)-doped CBP HIL is more than three times that of the device with a neat MoO(x) HIL estimated at an initial luminance of 1000 cd/m(2). The MoO(x)-doped HIL further ensures the feasibility of the simplified phosphorescent OLEDs for potential applications.

Panorama Phylogenetic Diversity and Distribution of Type A Influenza Virus

BackgroundType A influenza virus is one of important pathogens of various animals, including humans, pigs, horses, marine mammals and birds. Currently, the viral type has been classified into 16 hemagglutinin and 9 neuraminidase subtypes, but the phylogenetic diversity and distribution within the viral type largely remain unclear from the whole view.Methodology/Principal FindingsThe panorama phylogenetic trees of influenza A viruses were calculated with representative sequences selected from approximately 23000 candidates available in GenBank using web servers in NCBI and the software MEGA 4.0. Lineages and sublineages were classified according to genetic distances, topology of the phylogenetic trees and distributions of the viruses in hosts, regions and time.Conclusions/SignificanceHere, two panorama phylogenetic trees of type A influenza virus covering all the 16 hemagglutinin subtypes and 9 neuraminidase subtypes, respectively, were generated. The trees provided us whole views and some novel information to recognize influenza A viruses including that some subtypes of avian influenza viruses are more complicated than Eurasian and North American lineages as we thought in the past. They also provide us a framework to generalize the history and explore the future of the viral circulation and evolution in different kinds of hosts. In addition, a simple and comprehensive nomenclature system for the dozens of lineages and sublineages identified within the viral type was proposed, which if universally accepted, will facilitate communications on the viral evolution, ecology and epidemiology.