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1.
J Nanosci Nanotechnol ; 20(12): 7406-7411, 2020 Dec 01.
Artigo em Inglês | MEDLINE | ID: mdl-32711607

RESUMO

In this study, we investigated the hyperthermia efficiency of magnetic hyperthermia therapy (MHT), photo-thermal therapy (PTT), and the combination of both techniques by employing SPIO-based magneto-nanomicelles as the heating agents. Magneto-nanomicelles in aqueous suspension were exposed to 808-nm laser irradiation (PTT mode), alternating magnetic field (MHT mode), and both modalities (DUAL mode). All the three methods can offer effective temperature increases (above 20 °C). DUAL-mode resulted in an approximately 2-fold increase in heating efficiency (36 °C) compared with PTT or MHT alone. For in vivo experiments, a total of 24 Lewis carcinoma-bearing mice were randomly divided into four groups: the control group (no therapy), PTT, MHT, and DUAL group. In the three therapy groups, magneto-nanomicelles were injected into the tumor and the corresponding treatment measures were performed every other day for a total of three times each. MRI scans were used to calculate tumor volume after each treatment. One-way analysis of variance (ANOVA) was employed to compare the curative effect of different treatment groups. Compared with the control group, PTT, MHT, and DUAL groups all showed a significant inhibitory effect on tumor volume (P < 0.05). In the DUAL group, the mean tumor volume was smaller than that of the PTT or the MHT group. Our work demonstrated that hyperthermia using SPIO-based magnetonanomicelles has a remarkable suppressive effect in anticancer therapy. Moreover, the combined model of hyperthermia in vivo can achieve synthetic effects with shorter healing time by using the same magneto-nanomicelles.

2.
Sci Total Environ ; 732: 139334, 2020 Aug 25.
Artigo em Inglês | MEDLINE | ID: mdl-32438188

RESUMO

Humans can undergo circadian disruption and misalignment when living in closed environments without sufficient daylight. Therefore, it is of great significance to investigate the effects of artificial light on the circadian rhythm. In this work, the red, green, blue, warm white, and cool white (RGBWW) five-channel light-emitting diodes (LEDs) were fabricated as the only light sources in the closed environment. The LED mixed lighting showed a high color rendering index (CRI) all the time. During the day, the light simulated the daylight and increased the tunability of the circadian action factor (CAF) and correlated color temperature (CCT). At night, it maintained low CAF and CCT. Three subjects did irregular shift work in the closed environment for 38 days. Their plasma melatonin and daily activity were measured to assess the circadian rhythm. After 38 days, the subjects' peak melatonin times did not shift significantly (p = 0.676), while their peak melatonin concentrations increased apparently (p = 0.005). The start times of the least active 5-h period (L5) in one day fluctuated in a small range. The standard deviation (SD) was <15.11 min in most times. These results demonstrated that the subjects' rhythms maintained stable and were enhanced. The periods of circular cross-correlation between activity and CAF oscillated around 24 h (SD = 15.4 min), indicating the entrainment of light on the stable 24-h rhythm. It was concluded that the daylight-like LED lighting effectively entrained and enhanced the circadian rhythm in the closed environment.


Assuntos
Ritmo Circadiano , Temperatura Corporal , Cor , Humanos , Iluminação , Melatonina , Temperatura
3.
J Comput Biol ; 2020 Feb 12.
Artigo em Inglês | MEDLINE | ID: mdl-32048865

RESUMO

The problem of computing the rooted subtree prune and regraft (rSPR) distance of two phylogenetic trees is computationally hard and so is the problem of computing the hybridization number of two phylogenetic trees (denoted by Hybridization Number Computation [HNC]). Since they are important problems in phylogenetics, they have been studied extensively in the literature. Indeed, quite a number of exact or approximation algorithms have been designed and implemented for them. In this article, we design and implement several approximation algorithms for them and one exact algorithm for HNC. Our experimental results show that the resulting exact program is much faster (namely, more than 80 times faster for the easiest dataset used in the experiments) than the previous best and its superiority in speed becomes even more significant for more difficult instances. Moreover, the resulting approximation program's output has much better results than the previous bests; indeed, the outputs are always nearly optimal and often optimal. Of particular interest is the usage of the Monte Carlo tree search (MCTS) method in the design of our approximation algorithms. Our experimental results show that with MCTS, we can often solve HNC exactly within short time.

4.
Plant Cell ; 32(3): 703-721, 2020 03.
Artigo em Inglês | MEDLINE | ID: mdl-31919300

RESUMO

The phytohormone abscisic acid (ABA) and the Polycomb group proteins have key roles in regulating plant growth and development; however, their interplay and underlying mechanisms are not fully understood. Here, we identified an Arabidopsis (Arabidopsis thaliana) nodulin homeobox (AtNDX) protein as a negative regulator in the ABA signaling pathway. AtNDX mutants are hypersensitive to ABA, as measured by inhibition of seed germination and root growth, and the expression of AtNDX is downregulated by ABA. AtNDX interacts with the Polycomb Repressive Complex1 (PRC1) core components AtRING1A and AtRING1B in vitro and in vivo, and together, they negatively regulate the expression levels of some ABA-responsive genes. We identified ABA-INSENSITIVE (ABI4) as a direct target of AtNDX. AtNDX directly binds the downstream region of ABI4 and deleting this region increases the ABA sensitivity of primary root growth. Furthermore, ABI4 mutations rescue the ABA-hypersensitive phenotypes of ndx mutants and ABI4-overexpressing plants are hypersensitive to ABA in primary root growth. Thus, our work reveals the critical functions of AtNDX and PRC1 in some ABA-mediated processes and their regulation of ABI4.

5.
Nano Lett ; 20(1): 33-42, 2020 Jan 08.
Artigo em Inglês | MEDLINE | ID: mdl-31769995

RESUMO

The reconfigurability of the electrical heterostructure featured with external variables, such as temperature, voltage, and strain, enabled electronic/optical phase transition in functional layers has great potential for future photonics, computing, and adaptive circuits. VO2 has been regarded as an archetypal phase transition building block with superior metal-insulator transition characteristics. However, the reconfigurable VO2-based heterostructure and the associated devices are rare due to the fundamental challenge in integrating high-quality VO2 in technologically important substrates. In this report, for the first time, we show the remote epitaxy of VO2 and the demonstration of a vertical diode device in a graphene/epitaxial VO2/single-crystalline BN/graphite structure with VO2 as a reconfigurable phase-change material and hexagonal boron nitride (h-BN) as an insulating layer. By diffraction and electrical transport studies, we show that the remote epitaxial VO2 films exhibit higher structural and electrical quality than direct epitaxial ones. By high-resolution transmission electron microscopy and Cs-corrected scanning transmission electron microscopy, we show that a graphene buffered substrate leads to a less strained VO2 film than the bare substrate. In the reconfigurable diode, we find that the Fermi level change and spectral weight shift along with the metal-insulator transition of VO2 could modify the transport characteristics. The work suggests the feasibility of developing a single-crystalline VO2-based reconfigurable heterostructure with arbitrary substrates and sheds light on designing novel adaptive photonics and electrical devices and circuits.

6.
Adv Mater ; 32(6): e1905060, 2020 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-31854486

RESUMO

The discovery of hydrogen-induced electron localization and highly insulating states in d-band electron correlated perovskites has opened a new paradigm for exploring novel electronic phases of condensed matters and applications in emerging field-controlled electronic devices (e.g., Mottronics). Although a significant understanding of doping-tuned transport properties of single crystalline correlated materials exists, it has remained unclear how doping-controlled transport properties behave in the presence of planar defects. The discovery of an unexpected high-concentration doping effect in defective regions is reported for correlated nickelates. It enables electronic conductance by tuning the Fermi-level in Mott-Hubbard band and shaping the lower Hubbard band state into a partially filled configuration. Interface engineering and grain boundary designs are performed for Hx SmNiO3 /SrRuO3 heterostructures, and a Mottronic device is achieved. The interfacial aggregation of hydrogen is controlled and quantified to establish its correlation with the electrical transport properties. The chemical bonding between the incorporated hydrogen with defective SmNiO3 is further analyzed by the positron annihilation spectroscopy. The present work unveils new materials physics in correlated materials and suggests novel doping strategies for developing Mottronic and iontronic devices via hydrogen-doping-controlled orbital occupancy in perovskite heterostructures.

8.
J Comput Biol ; 2019 Oct 23.
Artigo em Inglês | MEDLINE | ID: mdl-31638413

RESUMO

Given a set [Formula: see text]. of phylogenetic trees with the same leaf-label set X, we wish to remove some leaves from the trees so that there is a tree T with leaf-label set X displaying all the resulting trees. Note that the labels of leaves removed from one input tree may be different from those of leaves removed from another input tree. One objective is to minimize the total number of leaves removed from the trees, whereas the other is to minimize the maximum number of leaves removed from an input tree. Chauve et al. refer to the problem with the first (respectively, second) objective as AST-LR (respectively, AST-LR-d), and they show that both problems are NP-hard, where NP is the class of problems solvable in non-deterministic polynomial time. They further present algorithms for the parameterized versions of both problems. In this article, we point out that their algorithm for the parameterized version of AST-LR is flawed and present a new algorithm. Since neither Chauve et al.'s algorithm for AST-LR-d nor our new algorithm for AST-LR looks practical, we further design integer-linear programming (ILP for short) models for AST-LR and AST-LR-d, and we discuss speedup issues when using popular ILP solvers (say, GUROBI or CPLEX) to solve the models. Our experimental results show that our ILP approach is quite efficient.

9.
Nat Commun ; 10(1): 4145, 2019 Sep 12.
Artigo em Inglês | MEDLINE | ID: mdl-31515482

RESUMO

Crystallographic dislocation has been well-known to be one of the major causes responsible for the unfavorable carrier dynamics in conventional semiconductor devices. Halide perovskite has exhibited promising applications in optoelectronic devices. However, how dislocation impacts its carrier dynamics in the 'defects-tolerant' halide perovskite is largely unknown. Here, via a remote epitaxy approach using polar substrates coated with graphene, we synthesize epitaxial halide perovskite with controlled dislocation density. First-principle calculations and molecular-dynamics simulations reveal weak film-substrate interaction and low density dislocation mechanism in remote epitaxy, respectively. High-resolution transmission electron microscopy, high-resolution atomic force microscopy and Cs-corrected scanning transmission electron microscopy unveil the lattice/atomic and dislocation structure of the remote epitaxial film. The controlling of dislocation density enables the unveiling of the dislocation-carrier dynamic relation in halide perovskite. The study provides an avenue to develop free-standing halide perovskite film with low dislocation density and improved carried dynamics.

10.
Plant Physiol ; 181(3): 1075-1095, 2019 11.
Artigo em Inglês | MEDLINE | ID: mdl-31471454

RESUMO

Cellular redox status plays critical roles in cell division and differentiation, but the underlying mechanism is unclear. Here we explored the effect of redox status on stem cell identity in distal stem cells (DSCs) of Arabidopsis (Arabidopsis thaliana) roots. Treatment with the reductive reagent glutathione and the oxidative reagent H2O2 inhibited DSC differentiation, as did endogenously altering reactive oxygen species production via various mutations. This suggests that both highly reductive and oxidative environments inhibit specification of stem cell identity. In our observations of mutant components of the CLAVATA3/ENDOSPERM SURROUNDING REGION 40 (CLE40)-ARABIDOPSIS CRINKLY4 (ACR4)/CLAVATA1 (CLV1)-WUSCHEL RELATED HOMEOBOX5 (WOX5) module, both reductive and oxidative reagents influenced DSC differentiation in wox5-1 and clv1-1, but not in acr4-2 or cle40 mutant plants. The stability of the receptor-like kinase ACR4 is modulated by redox status through endocytosis in root tips. ACR4 with multiple Cys mutations in the tumor necrosis factor receptor (TNFR) extracellular domain failed to undergo endocytosis. ACR4 with a complete deletion of the TNFR domain was localized directly to endosomes, bypassing the plasma membrane. Both mutations affected DSC differentiation, but not seed filling. Conversely, the intracellular domain of the ACR4 protein is partially required for seed filling, but not for DSC differentiation. Our study uncovers an important biological role of the TNFR domain in redox-mediated endocytosis of ACR4 in root DSC differentiation.

11.
Leuk Res ; 85: 106198, 2019 10.
Artigo em Inglês | MEDLINE | ID: mdl-31401408

RESUMO

The aim of this study was to investigate the role and underlying mechanism of circular RNA (circRNA) circPAN3 in mediating drug resistance in acute myeloid leukemia (AML). We first established two doxorubicin (ADM)-resistant AML cell lines and then utilized high-throughput RNA sequencing (RNA-seq) to compare their circRNA expression profiles with those of the parental cell lines. With bioinformatic analysis, we identified key circRNA molecules involved in drug resistance and validated our findings in clinical specimens. The target microRNAs (miRNAs) and downstream mRNAs were also explored bioinformatically. Using RNA interference technique, the potential mechanism was further investigated. Twenty-nine circRNAs were identified to be differentially expressed between ADM-resistant and sensitive cells. We found that circPAN3 is most likely a key mediator in the development of AML drug resistance, evidenced by the increased expression in ADM-resistant cell lines and BM samples from relapsed patients. Additionally, downregulation of circPAN3 by small interfering RNA (siRNA) significantly restored drug sensitivity to ADM in the two ADM-resistant cell lines, but lentivirus-mediated circPAN3 overexpression had the opposite effect. Subsequent bioinformatic analysis and mechanistic experiments revealed that circPAN3 may facilitate AML drug resistance through regulating autophagy and influencing expression of apoptosis-related proteins, while AMPK/mTOR signaling plays a key role in the regulation of circPAN3 on autophagy. These findings may provide new important insights into the role of circRNAs in mediating AML drug resistance, and suggest that circPAN3 might be a potential target for treatment of drug-resistance AML, which merits further investigation and validation.

12.
Nat Commun ; 10(1): 1764, 2019 04 16.
Artigo em Inglês | MEDLINE | ID: mdl-30992432

RESUMO

Unlike the vast majority of transition metal dichalcogenides which are semiconductors, vanadium disulfide is metallic and conductive. This makes it particularly promising as an electrode material in lithium-ion batteries. However, vanadium disulfide exhibits poor stability due to large Peierls distortion during cycling. Here we report that vanadium disulfide flakes can be rendered stable in the electrochemical environment of a lithium-ion battery by conformally coating them with a ~2.5 nm thick titanium disulfide layer. Density functional theory calculations indicate that the titanium disulfide coating is far less susceptible to Peierls distortion during the lithiation-delithiation process, enabling it to stabilize the underlying vanadium disulfide material. The titanium disulfide coated vanadium disulfide cathode exhibits an operating voltage of ~2 V, high specific capacity (~180 mAh g-1 @200 mA g-1 current density) and rate capability (~70 mAh g-1 @1000 mA g-1), while achieving capacity retention close to 100% after 400 charge-discharge steps.

13.
Nat Commun ; 10(1): 695, 2019 02 11.
Artigo em Inglês | MEDLINE | ID: mdl-30741944

RESUMO

The functionality and performance of a semiconductor is determined by its bandgap. Alloying, as for instance in InxGa1-xN, has been a mainstream strategy for tuning the bandgap. Keeping the semiconductor alloys in the miscibility gap (being homogeneous), however, is non-trivial. This challenge is now being extended to halide perovskites - an emerging class of photovoltaic materials. While the bandgap can be conveniently tuned by mixing different halogen ions, as in CsPb(BrxI1-x)3, the so-called mixed-halide perovskites suffer from severe phase separation under illumination. Here, we discover that such phase separation can be highly suppressed by embedding nanocrystals of mixed-halide perovskites in an endotaxial matrix. The tuned bandgap remains remarkably stable under extremely intensive illumination. The agreement between the experiments and a nucleation model suggests that the size of the nanocrystals and the host-guest interfaces are critical for the photo-stability. The stabilized bandgap will be essential for the development of perovskite-based optoelectronics, such as tandem solar cells and full-color LEDs.

14.
Anal Chem ; 91(3): 2128-2134, 2019 02 05.
Artigo em Inglês | MEDLINE | ID: mdl-30624057

RESUMO

Emerging nanomedical strategy is to construct a nanoagent that affords not only diagnostic and therapeutic functions but also imaging-guided treatment. It is crucial to understand the in vivo biological processes of nanoagents for improving theranostic function and biosafety. Herein, we report a multimodal photoacoustic/single-photon emission computed tomography (SPECT) imaging technique to dynamically monitor the in vivo behaviors of nanoagents. Near-infrared cypate-induced silk fibroin nanoassembly was chosen as the nanoagent object due to their promise in biocompatibility and aggregation-enhanced photothermal effect. This unique effect makes the nanoagents useful for the integration of photoacoustic imaging and photothermal therapy. Moreover, the nanoagents are also labeled with the radionuclides (99mTc) to render SPECT imaging. Multimodal photoacoustic/SPECT imaging provides real time, noninvasive, sensitive, and whole-body 3D information about nanoagents' distribution in vivo. These results highlight the significance of visualizing the in vivo behaviors of nanoagents and locating the tumor in vivo, substantially benefiting the better treatment planning.

15.
Adv Mater ; 31(1): e1803514, 2019 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-30368915

RESUMO

Following the rejuvenation of 3D organic-inorganic hybrid perovskites, like CH3 NH3 PbI3 , (quasi)-2D Ruddlesden-Popper soft halide perovskites R2 An -1 Pbn X3 n +1 have recently become another focus in the optoelectronic and photovoltaic device community. Although quasi-2D perovskites were first introduced to stabilize optoelectronic/photovoltaic devices against moisture, more interesting properties and device applications, such as solar cells, light-emitting diodes, white-light emitters, lasers, and polaritonic emission, have followed. While delicate engineering design has pushed the performance of various devices forward remarkably, understanding of the fundamental properties, especially the charge-transfer process, electron-phonon interactions, and the growth mechanism in (quasi)-2D halide perovskites, remains limited and even controversial. Here, after reviewing the current understanding and the nexus between optoelectronic/photovoltaic properties of 2D and 3D halide perovskites, the growth mechanisms, charge-transfer processes, vibrational properties, and electron-phonon interactions of soft halide perovskites, mainly in quasi-2D systems, are discussed. It is suggested that single-crystal-based studies are needed to deepen the understanding of the aforementioned fundamental properties, and will eventually contribute to device performance.

16.
Exp Hematol ; 70: 42-54.e3, 2019 02.
Artigo em Inglês | MEDLINE | ID: mdl-30395908

RESUMO

The contribution and role of circular RNAs (circRNAs) in mediating chemoresistance in acute myeloid leukemia (AML) are still poorly understood and need further investigation. In this study, we established a doxorubicin (ADM)-resistant THP-1 AML cell line (THP-1/ADM). A high-throughput microarray was used to identify circRNA expression profiles of THP-1/ADM cells and naive THP-1 cells. The identified potential functional circRNA molecule was further validated in THP-1/ADM cells and bone marrow (BM) specimens from 42 AML patients. The interactions with target microRNAs (miRNAs) and downstream messenger RNAs (mRNAs) were also explored. As a result, 49 circRNAs that are significantly differentially expressed between THP-1/ADM and THP-1 cells were identified. Of these circRNAs, downregulation of circPAN3 by small interfering RNA significantly restored ADM sensitivity of THP-1/ADM cells. Furthermore, BM samples from patients with refractory and recurrent AML showed increased expression of circPAN3. A detailed circRNA/miRNA/mRNA interaction network was predicated for this circRNA. Subsequent mechanistic experiments showed that downregulation of circPAN3 could decrease the expression of X-linked inhibitor of apoptosis protein (XIAP), but this effect was counteracted by miR-153-3p or miR-183-5p specific inhibitors. Luciferase experiments further demonstrated that these molecules are involved in the circPAN3 regulatory network. Our results revealed that circPAN3 may be a key mediator for chemoresistance of AML cells, which may depend on the circPAN3-miR-153-5p/miR-183-5p-XIAP axis. Our findings provide evidence that circPAN3 can be a valuable indicator for predicting clinical efficacy of chemotherapy in AML patients and also can serve as a potential target for reversing drug resistance in AML.


Assuntos
Resistencia a Medicamentos Antineoplásicos , Leucemia Mieloide Aguda/metabolismo , MicroRNAs/metabolismo , Proteínas de Neoplasias/metabolismo , RNA Neoplásico/metabolismo , Proteínas Inibidoras de Apoptose Ligadas ao Cromossomo X/metabolismo , Humanos , Leucemia Mieloide Aguda/tratamento farmacológico , Leucemia Mieloide Aguda/genética , MicroRNAs/genética , Proteínas de Neoplasias/genética , RNA Neoplásico/genética , Células THP-1 , Proteínas Inibidoras de Apoptose Ligadas ao Cromossomo X/genética
17.
Zhongguo Shi Yan Xue Ye Xue Za Zhi ; 26(6): 1688-1694, 2018 Dec.
Artigo em Chinês | MEDLINE | ID: mdl-30501705

RESUMO

OBJECTIVE: To investigate relationship of miRNA-132, miRNA-256, miRNA-143 and miRNA-145 level with antophagy and apoptosis of multiple mgeloma cells. METHODS: Human myeloma cell line U266 and normal CD138+ plasma cells were selected and used for study and detection, the 45 cases of MM were enrolled in MM group, and 40 normal persons were sellectod in control group. The expression of miRNA-132, miRNA-125b, miRNA-143 and miRNA-145 were measured by using qPCR, the expressions of autophagy-related protein (LC3-Ⅱ, LC3-Ⅰ, P62, beclin-1) and apoptosis-related molecules (cleaved-Caspase3, cleaved-Caspase7, BCL-2, BAX) were measured by using Western blot, respectively. The rate of apoptosis was measured by using flow cytometry. The correlation of miRNA expression level with clinical-related indexes including M protein, hemoglobin, ß2-MG, lactate dehydrogenase, albumin, creatinine and serum calcium was analyzed. RESULTS: Compared with normal plasma cells, the expression of miRNA-132 and miRNA-125b in myeloma cells increased significantly (P<0.05), and the expression of miRNA-143 and miRNA-145 decreased significantly (P<0.05), but the expression of LC3-Ⅱ/LC3-Ⅰ and Beclin-1 increased significantly (P<0.05). The expression of P62. BAX, cleaved-Caspase3 and cleaved-Caspase7 decreased significantly (P<0.05), the BCL-2 expression increased significantly (P<0.05), but the rate of apoptosis decreased (P<0.05). After transfection with miRNA-125b mimic or miRNA-143 inhibitor by using the cationic liposomes, the LC3-Ⅱ /LC3-Ⅰ of normal plasma cells increased significantly (P<0.05), the expression of Beclin-1 significantly increased (P<0.05), the expression of P62 decreased significantly (P<0.05), and the apoptosis rate decreased (P<0.05). However, the apoptosis rate was not significantly changed after addition of the autophagic inhibitor 3-MA in the reaction system(P>0.05). The expressions of miRNA-132, miRNA-125b, miRNA-143 and miRNA-145 were significantly different between DS and ISS staging group, also between the patients with abnormal and normal chromosome karyotype (P<0.05). The miRNA-125b and miRNA-143 significantly correlated with the levels of ß2-MG, albumin and hemoglobin (P<0.05). CONCLUSION: The expressions of miRNA-132, miRNA-125b, miRNA-143 and miRNA-145 in patients with multiple myeloma closely relate with the clinical characteristics. Both over-expression of miRNA-125b and down-expression of miRNA-143 inhibit the apoptosis of myeloma cells by up-regulation of autophagy.


Assuntos
Autofagia , Mieloma Múltiplo , Apoptose , Proteína Beclina-1 , Linhagem Celular Tumoral , Humanos , MicroRNAs
18.
J Phys Chem Lett ; 9(23): 6676-6682, 2018 Dec 06.
Artigo em Inglês | MEDLINE | ID: mdl-30398890

RESUMO

Despite their weak nature, van der Waals (vdW) interactions have been shown to effectively control the optoelectronic and vibrational properties of layered materials. However, how vdW effects exist in Ruddlesden-Popper layered halide perovskites remains unclear. Here we reveal the role of interlayer vdW force in Ruddlesden-Popper perovskite in regulating phase-transition kinetics and carrier dynamics based on high-quality epitaxial single-crystalline (C4H9NH3)2PbI4 flakes with controlled dimensions. Both substrate-perovskite epitaxial interaction and interlayer vdW interaction play significant roles in suppressing the structural phase transition. With reducing flake thickness from ∼100 to ∼20 nm, electron-phonon coupling strength decreases by ∼30%, suggesting the ineffectiveness of phonon confinement of the natural quantum wells. Therefore, the conventional understanding that vdW perovskite is equivalent to a multiple quantum well has to be substantially amended due to significant nonlocal phononic effects in the layered crystal, where intralayer interaction is not drastically different from the interlayer force.

19.
Artigo em Inglês | MEDLINE | ID: mdl-30387740

RESUMO

Due to hybridization events in evolution, studying two different genes of a set of species may yield two related but different phylogenetic trees for the set of species. In this case, we want to measure the dissimilarity of the two trees. The rooted subtree prune and regraft (rSPR) distance of the two trees has been used for this purpose. The problem of computing the rSPR distance of two given trees has many applications but is NP-hard. Accordingly, a number of programs have been developed for solving the problem either exactly or approximately. In this paper, we develop two new programs one of which solves the problem exactly and outperforms the previous best (namely, Whidden et al.'s rSPR-v1.3.0) significantly, while the other solves the problem approximately and outputs significantly better lower and upper bounds on the rSPR distance of the two given trees than the previous best due to Schalekamp et al. Our programs can be downloaded at http://rnc.r.dendai.ac.jp/rspr.html.

20.
Sci Adv ; 4(5): eaar3679, 2018 05.
Artigo em Inglês | MEDLINE | ID: mdl-29806024

RESUMO

The success of strain engineering has made a step further for the enhancement of material properties and the introduction of new physics, especially with the discovery of the critical roles of strain in the heterogeneous interface between two dissimilar materials (for example, FeSe/SrTiO3). On the other hand, the strain manipulation has been limited to chemical epitaxy and nanocomposites that, to a large extent, limit the possible material systems that can be explored. By defect engineering, we obtained, for the first time, dense three-dimensional strongly correlated VO2±Î´ epitaxial nanoforest arrays that can be used as a novel "substrate" for dynamic strain engineering, due to its metal-insulator transition. The highly dense nanoforest is promising for the possible realization of bulk strain similar to the effect of nanocomposites. By growing single-crystalline halide perovskite CsPbBr3, a mechanically soft and emerging semiconducting material, onto the VO2±Î´, a heterogeneous interface is created that can entail a ~1% strain transfer upon the metal-insulator transition of VO2±Î´. This strain is large enough to trigger a structural phase transition featured by PbX6 octahedral tilting along with a modification of the photoluminescence energy landscape in halide perovskite. Our findings suggest a promising strategy of dynamic strain engineering in a heterogeneous interface carrying soft and strain-sensitive semiconductors that can happen at a larger volumetric value surpassing the conventional critical thickness limit.

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