We report the observation of a nontrivial spin texture in Dirac node arcs, i.e., novel topological objects formed when Dirac cones of massless particles extend along an open one-dimensional line in ...momentum space. We find that such states are present in all the compounds of the tetradymite M2Te2X family (M = Ti, Zr, or Hf and X = P or As) regardless of the weak or strong character of the topological invariant. The Dirac node arcs in tetradymites are thus the simplest possible textbook example of a type-I Dirac system with a single spin-polarized node arc.
Chemical genetic screening of small-molecule libraries has been a promising strategy for discovering unique and novel therapeutic compounds. However, identifying the targets of lead molecules that ...arise from these screens has remained a major bottleneck in understanding the mechanism of action of these compounds. Here, we have coupled the screening of a cysteine-reactive fragment-based covalent ligand library with an isotopic tandem orthogonal proteolysis-enabled activity-based protein profiling (isoTOP-ABPP) chemoproteomic platform to rapidly couple the discovery of lead small molecules that impair pancreatic cancer pathogenicity with the identification of druggable hotspots for potential cancer therapy. Through this coupled approach, we have discovered a covalent ligand DKM 2–93 that impairs pancreatic cancer cell survival and in vivo tumor growth through covalently modifying the catalytic cysteine of the ubiquitin-like modifier activating enzyme 5 (UBA5), thereby inhibiting its activity as a protein that activates the ubiquitin-like protein UFM1 to UFMylate proteins. We show that UBA5 is a novel pancreatic cancer therapeutic target and show DKM 2–93 as a relatively selective lead inhibitor of UBA5. Our results underscore the utility of coupling the screening of covalent ligand libraries with isoTOP-ABPP platforms for mining the proteome for druggable hotspots for cancer therapy.
The present status of kinetic modeling of particle dynamics in hydrogen negative ion (H−) source plasmas and their comparisons with experiments are reviewed and discussed with some new results. The ...main focus is placed on the following topics, which are important for the research and development of H− sources for intense and high-quality H− ion beams: (i) effects of non-equilibrium features of electron energy distribution function on volume and surface H− production, (ii) the origin of the spatial non-uniformity in giant multi-cusp arc-discharge H− sources, (iii) capacitive to inductive (E to H) mode transition in radio frequency-inductively coupled plasma H− sources and (iv) extraction physics of H− ions and beam optics, especially the present understanding of the meniscus formation in strongly electronegative plasmas (so-called ion-ion plasmas) and its effect on beam optics. For these topics, mainly Japanese modeling activities, and their domestic and international collaborations with experimental studies, are introduced with some examples showing how models have been improved and to what extent the modeling studies can presently contribute to improving the source performance. Close collaboration between experimental and modeling activities is indispensable for the validation/improvement of the modeling and its contribution to the source design/development.
We searched for the 6α-condensed state in 24Mg by measuring the C12+12C scattering with the SAKRA Si detector array at Ecm=17.5–25.0 MeV. By using the invariant-mass method for the detected 3α ...particles, the inclusive cross sections for the C12+12C→12C(02+)+X and C12(31−)+X reactions were determined. In addition, the missing-mass spectroscopy was successfully utilized to determine the excitation energy of the residual C12 nucleus and the exclusive cross sections for the C12+12C→12C(02+)+12C(01+), C12(02+)+12C(21+), and C12(02+)+12C(02+) reactions. In both the inclusive C12(02+)+X channel and the exclusive C12(02+)+12C(01+) channel, the cross section peaked at Ecm=19.4 MeV, which correspond to the excitation energy of Ex=33.3 MeV in 24Mg. This 19.4-MeV state is a candidate for the 6α-condensed state because of the agreement of the excitation energy with the theoretical value and its decay property. In the exclusive C12(02+)+12C(02+) channel, a broad state was observed at Ecm=22.5 MeV, which correspond to the excitation energy of Ex=36.4 MeV in 24Mg. From the angular distribution of the differential cross section, the spin and parity of this 22.5-MeV state was assigned to be 4+. In addition, a 2+ state was suggested at the low-energy side of the 22.5-MeV state. Because their excitation energies are higher than the theoretical value of the 6α-condensed state, these states might be excited states of the 6α-condensed state such as the 22+ and 41+ states in C12.
Abstract
We demonstrate, for the first time, the direct generation of a bottle beam with a well-isolated three-dimensional zero-intensity dark core (high potential barrier) from a compact intracavity ...frequency-doubled Nd:YVO
4
laser with a nearly hemispherical cavity. We also numerically calculate the physical properties of the generated bottle beam using a coherent superposition of a series of frequency-locked Laguerre–Gaussian modes.
Strong spin polarization of the photocurrent from bulk continuum states of Bi(111) is experimentally observed. On the basis of ab initio one-step photoemission theory the effect is shown to originate ...from the strong polarization of the initial states at the surface and to be the result of the surface sensitivity of photoemission. Final state effects cause deviations of the k{∥} dependence of polarization from strictly antisymmetric relative to Γ.
Summary
Background
In vivo two‐photon tomography is a novel noninvasive three‐dimensional optical skin imaging technology with subcellular resolution which enables the sensitive detection of ...endogenous fluorophores. One of these fluorophores, NAD(P)H (a coenzyme which plays an important role in the release of free energy during glycolysis, and influences filaggrin and lipid synthesis), can be selectively detected in keratinocytes (granular cells) with two‐photon tomography.
Objectives
To quantify NAD(P)H levels in subsurface human facial skin in vivo as a measure to determine if there are changes with age.
Methods
A total of 80 healthy Asian females were enrolled in this study, aged 21–68 years. Measurements were performed on facial skin using in vivo two‐photon tomography (DermaInspect/MPTflex™, JenLab GmbH, Jena, Germany). The laser beam scans a skin field of interest in pulses, focused at a depth to reach the granular layer. The near‐infrared laser pulses excite the endogenous fluorophores NAD(P)H. Image processing was performed to obtain high‐resolution autofluorescence images (optical biopsies) and to quantify the fluorescent grey scale to determine NAD(P)H levels. Additional skin surface measures taken were hydration (corneometer), elasticity (cutometer) and wrinkles (image capture and analysis).
Results
Statistically significant changes in all measured parameters as a function of age were observed. Most importantly, the mean fluorescent grey scale values for NAD(P)H in the youngest group studied (women in their 20s) was 38·8 (SD ± 12·39), while that of the oldest group studied (women in their 60s) was 32·7 (SD ± 12·47). These NAD(P)H levels are statistically significantly different (P = 0·0078).
Conclusions
The level of NAD(P)H in the epidermis is significantly greater in younger vs. older skin in vivo. This likely reflects decreased production and/or increased degradation of NAD(P)H in older skin, possibly as a result of chronological ageing and environmental damage (e.g. photodamage). NAD(P)H levels in epidermal skin may be a useful biomarker of skin ageing in vivo. It is also likely that maintaining NAD(P)H production is a useful approach to maintaining good skin condition and caring for ageing skin.
Abstract
The C
2
v
surface symmetry of W(110) strongly influences a spin-orbit-induced Dirac-cone-like surface state and its characterization by spin- and angle-resolved photoelectron spectroscopy. ...In particular, using circular polarized light, a distinctive
k
-dependent spin texture is observed along the
$$\overline{{\boldsymbol{\Gamma }}{\boldsymbol{H}}}$$
Γ
H
¯
direction of the surface Brillouin zone. For all spin components P
x
, P
y
, and P
z
, non-zero values are detected, while the initial-state spin polarization has only a P
y
component due to mirror symmetry. The observed complex spin texture of the surface state is controlled by transition matrix element effects, which include orbital symmetries of the involved electron states as well as the geometry of the experimental set-up.
Spin-orbit-induced spin splitting of surface states has attracted great interest in recent years because of the high potential for technological applications associated with this phenomenon. This ...Rashba physics is found in a variety of systems ranging from simple metals like Ag or Au to the so-called topological insulators which are of special interest in spintronics. A very special and unique case is found at the W(110) surface. In this metal d-like surface resonances exhibit energy dispersions and spin-polarization structures which are reminiscent of topological surface states. In our theoretical study, we present a complete analysis of the surface electronic structure of W(110) and show that the atypical linear-shaped dispersion behavior is triggered by the amount of charge transfer from the bulk into the first few vacuum layers. Furthermore, we compare our theoretical spectra with experimental photoemission data on W(110) and demonstrate that our state-of-the-art photoemission theory is able to deal with these peculiar surface features in a quantitative way. Our analysis is based on a generalization of the relativistic one-step model of photoemission, recently extended by us to study photoelectron spectroscopy at high photon energies. This theoretical approach was realized in the full spin-density matrix formulation for the photocurrent, which allows for an unrestricted calculation of the spin-polarization vector of the photoelectron. As an additional result we predict very peculiar behavior of these surface features showing up even at soft and hard x-ray energies. This observation is very surprising, unprecedented for ordinary surface features on simple metal surfaces.
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