The effect of grain boundary structure, either rough or faceted, on diffusion‐induced grain boundary migration (DIGM) has been investigated in BaTiO3. SrTiO3 particles were scattered on the polished ...surfaces of two kinds of BaTiO3 samples with faceted and rough boundaries and annealed in air for the samples with faceted boundaries and in H2 for those with rough boundaries. In the BaTiO3 samples with rough boundaries, an appreciable grain boundary migration occurred. In contrast, grain‐boundary migration hardly occurred in the BaTiO3 samples with faceted boundaries. The migration suppression observed in the sample with faceted boundaries was attributed to a low boundary mobility. The present experimental results show that DIGM is strongly affected by the boundary structure and can be suppressed by structural transition of boundaries from rough to faceted.
Considerable evidence suggests that variations in the properties of topological insulators (TIs) at the nanoscale and at interfaces can strongly affect the physics of topological materials. ...Therefore, a detailed understanding of surface states and interface coupling is crucial to the search for and applications of new topological phases of matter. Currently, no methods can provide depth profiling near surfaces or at interfaces of topologically inequivalent materials. Such a method could advance the study of interactions. Herein, we present a noninvasive depth-profiling technique based on β-detected NMR (β-NMR) spectroscopy of radioactive â¸Li ⺠ions that can provide âone-dimensional imagingâ in films of fixed thickness and generates nanoscale views of the electronic wavefunctions and magnetic order at topological surfaces and interfaces. By mapping the â¸Li nuclear resonance near the surface and 10-nm deep into the bulk of pure and Cr-doped bismuth antimony telluride films, we provide signatures related to the TI properties and their topological nontrivial characteristics that affect the electronânuclear hyperfine field, the metallic shift, and magnetic order. These nanoscale variations in β-NMR parameters reflect the unconventional properties of the topological materials under study, and understanding the role of heterogeneities is expected to lead to the discovery of novel phenomena involving quantum materials.
Electrical stress and 10-keV x-ray and 1.8-MeV proton irradiation and annealing responses are evaluated for graphene-based non-volatile memory devices. The memory characteristics of these structures ...derive primarily from hysteretic charge exchange between the graphene and interface and border traps, similar to the operation of metal-nitride-oxide-semiconductor memory devices. Excellent stability and memory retention are observed for ionizing radiation exposure or constant-voltage stress. Cycling of the memory state leads to a significant reduction in memory window.
A SiGe/Si Multiple Quantum Wells (MQWs) structure is proposed for highly sensitive photodetection. A large photoconductive gain is obtained because of the unique SiGe/Si band structure, i.e., a large ...band offset in the valence band, but a small band offset in the conduction band. Such a structure allows the trapping of photogenerated holes inside the valance band quantum wells. Alternatively, photogenerated electrons appear in shallow quantum wells and have relatively high mobility. These give rise to a large photoconductive gain. The calculated photoconductive gain for this structure exceeds 2
×
10
7. Experimental results confirmed a high gain of the structure.
A
bstract
Using data samples with an integrated luminosity of 6
.
4 fb
−
1
collected by the BESIII detector operating at the BEPCII storage ring, the process of
e
+
e
−
→
γϕJ/ψ
is studied. The ...processes of
e
+
e
−
→
ϕχ
c
1
,
c
2
,
χ
c
1
,
c
2
→
γJ/ψ
are observed with a significance of more than 10
σ
. The
s
-dependent cross section of
e
+
e
−
→
ϕχ
c
1
,
c
2
is measured between 4.600 and 4.951 GeV, and evidence of a resonance structure is found for the first time in the
ϕχ
c
2
process. We also search for the processes of
e
+
e
−
→
γX
(4140),
γX
(4274) and
γX
(4500) via the
γϕJ/ψ
final state, but no obvious structures are found. The upper limits on the production cross section times the branching fraction for these processes at the 90% confidence level are reported.
Genetic transformation of plant cells by Agrobacterium tumefaciens represents a unique case of trans-kingdom sex requiring the involvement of both bacterial virulence proteins and plant-encoded ...proteins. We have developed in planta and leaf-disk assays in Nicotiana benthamiana for identifying plant genes involved in Agrobacterium-mediated plant transformation using virus-induced gene silencing (VIGS) as a genomics tool. VIGS was used to validate the role of several genes that are either known or speculated to be involved in Agrobacterium-mediated plant transformation. We showed the involvement of a nodulin-like protein and an alpha-expansin protein (alpha-Exp) during Agrobacterium infection. Our data suggest that alpha-Exp is involved during early events of Agrobacterium-mediated transformation but not required for attaching A. tumefaciens. By employing the combination of the VIGS-mediated forward genetics approach and an in planta tumorigenesis assay, we identified 21 ACG (altered crown gall) genes that, when silenced, produced altered crown gall phenotypes upon infection with a tumorigenic strain of A. tumefaciens. One of the plant genes identified from the screening, Histone H3 (H3), was further characterized for its biological role in Agrobacterium-mediated plant transformation. We provide evidence for the role of H3 in transfer DNA integration. The data presented here suggest that the VIGS-based approach to identify and characterize plant genes involved in genetic transformation of plant cells by A. tumefaciens is simple, rapid, and robust and complements other currently used approaches.
Si-based normal incident mid-infrared photodetectors using Ge dots were investigated. P–I–P structures of boron-doped Ge dots embedded in the intrinsic region were grown using solid source molecular ...beam epitaxy. The dark current was strongly dependent on the doping level in Ge dot. The structure grown at 700
°C exhibited photoresponse peaking at 3.5
μm. FTIR measurements on identical structure showed an absorption band consistent with the photocurrent spectra. At lower temperatures, the response intensity decreased due to freeze-out of the holes. The devices also showed photovoltaic effect. The response increased with increasing bias.
This paper explores and compares the characteristics of eight different kinds of Cu(In, Ga)Se2 (CIGS) solar cells. Through the technique of chemical bath deposition (CBD), single- (i-ZnO) and ...double-layer (ZnS/CdS) CIGS cells were prepared and evaluated. The results of this research signify the potential of high-performance CIGS cells for photovoltaic (PV) industrial applications. This study focused on the growth-dependency and optical properties of ZnS/CdS-buffer stacked thin films, which were prepared through the CBD process. The best sample developed from this process consisted of a double-layer buffer and no i-ZnO layer. This sample yielded a conversion efficiency (η) of 9.23% and a short-circuit current density (JSC) of 26.72mA/cm2. The performance of this sample was about 25% (absolute gain) better than that of the standard CdS cells.
Furthermore, the average quantum efficiency in the short wavelength range (350–500nm) for two of the ZnS/CdS buffer structures was 6.8% better than that of a single-layer CdS cell. This improvement can be attributed to the anti-reflective effect of the ZnS/CdS buffer structure, which increases the light-intensity incident on the main absorption layer. In addition, the ZnS/CdS-buffer layer not only eliminates the need for an i-ZnO layer but also reduces the usage of toxic Cd. The procedures to develop these flexible CIGS cells containing a ZnS/CdS buffer structure are simple, efficient, and reliable. These eco-friendly cells could be effectively applied to mass production for commercial PV applications.
•We present a new structure to fabricate CIGS thin-film solar cells for better merits.•The structure improves cost, conversion efficiency and reduces chemical pollution.•The structure includes ZnS/CdS buffer with/without i-ZnO layers on the CIGS absorber.•The beat features of η=9.23%, JSC=26.72mA/cm2 and EQE for the short-wavelength range were improved.•The optimal cell could be effectively and eco-friendly applied to commercial production
HORMA domain‑containing protein 1 (HORMAD1), is normally expressed only in the germline, but is frequently re‑activated in human triple‑negative breast cancer (TNBC); however, its function in TNBC is ...largely unknown. In the present study, the expression and biological significance of HORMAD1 in human TNBC was evaluated. Bioinformatics analysis and reverse transcription‑quantitative PCR were used to evaluate HORMAD1 expression in datasets and cell lines. HORMAD1 protein expression was detected in TNBC samples using immunohistochemical assays, and the effect of HORMAD1 on cell proliferation was determined using Cell Counting Kit‑8, plate colony formation and standard growth curve assays. Cell cycle, reactive oxygen species (ROS) and apoptosis analyses were conducted using flow cytometry. The activity of caspases was measured using caspase activity assay kit. The levels of key apoptosis regulators and autophagy markers were detected by western blot analysis. TNBC cell survival and apoptosis were not influenced by small interfering RNA targeting HORMAD1 alone; however, HORMAD1 knockdown enhanced autophagy and docetaxel (Doc)‑induced apoptosis, compared with the control group. Furthermore, higher ROS levels and caspase‑3, ‑8 and ‑9 activity were detected in MDA‑MB‑436 TNBC cells with HORMAD1 knockdown upon exposure to Doc. The levels of the induced DNA damage marker γH2AX were also higher, while those of the DNA repair protein RAD51 were lower in TNBC cells with HORMAD1 knockdown compared with the controls. Furthermore, the expression of the autophagy marker P62 was enhanced in MDA‑MB‑231 cells in response to HORMAD1 overexpression. Notably, Doc‑induced apoptosis was similarly increased by both HORMAD1 overexpression and treatment with the autophagy inhibitor, 3‑methyladenine (3MA); however, the Doc‑induced increase in autophagy was not inhibited by 3MA. The present data indicated that HORMAD1 was involved in autophagy and that the inhibition of autophagy can partially enhance the induction of apoptosis by Doc. The role of HORMAD1 in the DNA damage tolerance of tumor cells may be the main reason for Doc resistance; hence, HORMAD1 could be an important therapeutic target in TNBC.
PDF
