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During deposition, modification, and etching of thin films and nanomaterials in reactive plasmas, many active species can interact with the sample simultaneously. This includes reactive neutrals formed by fragmentation of the feed gas, positive ions, and electrons generated by electron-impact ionization of the feed gas and fragments, excited states (in particular, long-lived metastable species), and photons produced by spontaneous de-excitation of excited atoms and molecules. Notably, some of these species can be transiently present during the different phases of plasma processing, such as etching of thin layer deposition. To monitor plasma–surface interactions during materials processing, a new system combining beams of neutral atoms, positive ions, UV photons, and a magnetron plasma source has been developed. This system is equipped with a unique ensemble of in-plasma surface characterization tools, including (1) a Rutherford Backscattering Spectrometer (RBS), (2) an Elastic Recoil Detector (ERD), and (3) a Raman spectroscopy system. RBS and ERD analyses are carried out using a differentially pumped 1.7 MV ion beam line Tandetron accelerator generating a beam at grazing incidence. The ERD system is equipped with an absorber and is specifically used to detect H initially bonded to the surface; higher resolution of surface H is also available through nuclear reaction analysis. In parallel, an optical port facing the substrate is used to perform Raman spectroscopy analysis of the samples during plasma processing. This system enables fast monitoring of a few Raman peaks over nine points scattered on a 1.6 × 1.6 mm2 surface without interference from the inherent light emitted by the plasma. Coupled to the various plasma and beam sources, the unique set of in-plasma surface characterization tools detailed in this study can provide unique time-resolved information on the modification induced by plasma. By using the ion beam analysis capability, the atomic concentrations of various elements in the near-surface (e.g., stoichiometry and impurity content) can be monitored in real-time during plasma deposition or etching. On the other hand, the evolution of Raman peaks as a function of plasma processing time can contribute to a better understanding of the role of low-energy ions in defect generation in irradiation-sensitive materials, such as monolayer graphene. [ABSTRACT FROM AUTHOR]

Using an invariant expansion, we build an Hamiltonian describing the influence of the crystal-field, the electron-hole exchange interaction, and any symmetry-breaking perturbations on the fine structure of excitons bound to systems of reduced symmetry: D2d, C3v, and C2v. Several perturbations are considered, including, but not limited to, an electric field, a magnetic field, a strain field, and their combinations. For each symmetry system considered, symmetrized excitonic wave functions, build from heavy- and light-holes states, are used to expand the Hamiltonian in the form of matrices, whose eigenvalues directly provide the energy of the excitonic states and whose eigenstates can be used to determine oscillator strengths of optical transitions. Using this model, we satisfactorily reproduce the excitonic emission observed from nitrogen dyads in GaAs and tellurium dyads in strained ZnSe. We also present Hamiltonians for independent heavy- and light-hole subsystems. Comparing the two models, we demonstrate that the splitting observed in strained quantum dots of C2v symmetry does not necessarily imply a significant anisotropic exchange interaction. This splitting can be produced by a weak coupling between heavy- and light-hole bands. [ABSTRACT FROM AUTHOR]

We present the design of a confocal microscope adapted for optical spectroscopy and imaging at cryogenic temperatures. This system is based on the existing approach of partly inserting the optical components of the microscope inside a helium-bath cryostat. It provides a spatial resolution approaching the diffraction limit with a mechanical stability allowing uninterrupted integration times exceeding 10 h and allows keeping track of a single emitter for unlimited periods of time. Furthermore, our design allows scanning the excitation spot and detection area independently of the sample position. This feature provides the means to perform probeless transport experiments on one-dimensional nanostructures. The scanning capabilities of this microscope are fully detailed and characterized using the photoluminescence of single nitrogen dyads at 4.5 K. [ABSTRACT FROM AUTHOR]

The magnetic and structural properties of MBE-grown films of Zn1− xCr xTe were investigated. The magnetization versus magnetic field ( M–H) measurement of Zn1− xCr xTe ( x = 0.01–0.17) showed clear hysteresis loop at low temperatures. The ferromagnetic transition temperature ( TC) estimated from the Arrott-plot analysis increased almost linearly with the Cr composition ( x) up to 275 K at x = 0.17. However, in the magnetization versus temperature ( M–T) measurement, the irreversibility between the zero-field-cooled (ZFC) and field-cooled (FC) processes was observed. This is typically observed in the magnetic random system such as spin-glass or superparamagnetic phase. In the high resolution transmission microscopy (HRTEM) observations, structural defects such as stacking faults and polycrystalline-like structure were observed at high Cr compositions, whereas any apparent precipitates of different phases were not seen in all the range of Cr compositions examined. The correlation of the observed magnetic randomness with the local structural defects was discussed. [ABSTRACT FROM AUTHOR]

We investigated the correlation between the Rashba spin–orbit coefficient α and potential shape of the quantum wells (QW), where α values are experimentally deduced from the weak antilocalization analysis. We studied the gate I– V properties of the QW samples and have obtained results consistent with the potential shapes predicted for these QWs. [ABSTRACT FROM AUTHOR]

The effects of a vertical electric field on the fine structure splitting of neutral exciton of monolayer fluctuation GaAs quantum dots were investigated. Using the gate voltage between the top gate electrode and the bottom n-GaAs substrate, the fine structure splitting of the neutral exciton was tuned to 15–30 μeV. Photon correlation measurements demonstrate neutral exciton single photon emission and neutral exciton—biexciton cascaded emission. [ABSTRACT FROM AUTHOR]

Electric and magnetic properties were investigated on p-type Zn1-xCrxTe doped with nitrogen (N) as an acceptor. Thin films of p-Zn1-xCrxTe (x≤=0.09) were grown by molecular-beam epitaxy with the supply of N2 gas excited by rf plasma. With the increase of Cr composition x at an almost fixed N concentration of the order of 1020 cm-3, the temperature dependence of resistivity changed from metallic behavior to an insulating one, accompanied with a significant decrease of the hole concentration. The magnetization measurements revealed that ferromagnetic behaviors observed in undoped Zn1-xCrxTe were suppressed due to the nitrogen doping; with N concentrations of the order of 1020 cm-3, hysteresis loops in the magnetization curve disappeared, the magnitude of magnetization decreased, and the ferromagnetic transition were not observed down to 2 K according to the Arrott plot analysis. These experimental findings are discussed on the basis of the ferromagnetic double exchange interaction which is considered to work on the Cr 3d impurity level formed in the band gap of ZnTe. [ABSTRACT FROM AUTHOR]

We report the growth of Mn-doped wurtzite GaN epilayers by nitrogen plasma-assisted molecular beam epitaxy, with a systematic attention to the dependence on the growth conditions. The addition of Mn modifies the growth diagram related to the Ga/N flux ratio. In particular, the stable Ga-bilayer coverage on the growth surface for the Ga-rich condition is destabilized in the presence of Mn. Mn incorporation in the epilayers is found to strongly depend on the Ga/N flux ratio: it varies by two orders of magnitude between the Ga-rich and the N-rich growth conditions. X-ray diffraction measurements on epilayers grown in the stoichiometric condition reveal a clear contrast between the precipitation of perovskite GaMn[sub 3]N clusters at Mn compositions higher than 1.7%, and the single phase of wurtzite Ga[sub 1-x]Mn[sub x]N at lower Mn compositions. © 2003 American Institute of Physics. [ABSTRACT FROM AUTHOR]

The authors describe surgical occlusion with levator resection and partial tarsorrhaphy as a treatment for nystagmus with oscillopsia refractory to medical or surgical therapies. This was a case of Bardet-Biedl syndrome with high myopia and acquired sensory pendular nystagmus in both eyes, where a well-known technique was applied to a novel indication. Permanent occlusion of the left eye led to significant improvement in visual acuity and reduced oscillopsia, enhancing the psychological and social functioning. This case highlights the complexity of treating refractory nystagmus with oscillopsia and proposes surgical occlusion as a viable option for improving patient outcomes in severe cases. [ J Pediatr Ophthalmol Strabismus . 2024;61(6):e63-e65.] .

Purpose: To report a case of a Henle fiber layer hemorrhage as the initial manifestation of Factor V Leiden disease., Methods: Case report and literature review., Results: A healthy 19-year-old patient presented with a spontaneous Henle fiber layer (HFL) hemorrhage. The genetic analysis showed a previously unknown homozygous Factor V Leiden Mutation. No specific treatment was given due to the patient's good visual acuity and favorable prognosis, but the diagnosis of a Factor V Leiden mutation enabled a correct therapeutic management to be followed by the patient., Conclusion: Advances in eye imaging allow to detect ocular findings that may lead to an early diagnosis and treatment. To the best of our knowledge, this is the first case of a HFL hemorrhage as the initial manifestation of Factor V Leiden disease. Further research is needed to identify the pathways linking these findings., Competing Interests: Declaration of conflicting interestsThe author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.

Dengue vaccine trials have revealed deficits in our understanding of the mechanisms of protective immunity, demonstrating a need to measure epitope-specific antibody responses against each DENV serotype. HmAb 5J7 binds to a complex, 3-monomer spanning quaternary epitope in the DENV3 envelope (E) protein, but it is unclear whether all interactions are needed for neutralization. Structure guided design and reverse genetics were used to sequentially transplant larger portions of the DENV3-specific 5J7 mAb epitope into dengue virus serotype 4 (DENV4). We observed complete binding and neutralization only when the entire 3 monomer spanning epitope was transplanted into DENV4, providing empirical proof that cooperative monomer-hmAb 5J7 interactions maximize activity. The rDENV4/3 virus containing the most expanded 5J7 epitope was also significantly more sensitive than WT DENV4 to neutralization by DENV3 primary immune sera. We conclude that the hinge-spanning region of the 5J7 quaternary epitope is a target for serotype-specific neutralizing antibodies after DENV3 infection.

The efficacy of existing therapies and the discovery of innovative treatments for central nervous system (CNS) diseases have been limited by the lack of appropriate methods to investigate complex molecular processes at the synaptic level. To improve our capability to investigate complex mechanisms of synaptic signaling and remodeling, we designed a fluorescence hyperspectral imaging platform to simultaneously track different subtypes of individual neurotransmitter receptors trafficking in and out of synapses. This imaging platform allows simultaneous image acquisition of at least five fluorescent markers in living neurons with a high-spatial resolution. We used quantum dots emitting at different wavelengths and functionalized to specifically bind to single receptors on the membrane of living neurons. The hyperspectral imaging platform enabled the simultaneous optical tracking of five different synaptic proteins, including subtypes of glutamate receptors (mGluR and AMPAR) and postsynaptic signaling proteins. It also permitted the quantification of their mobility after treatments with various pharmacological agents. This technique provides an efficient method to monitor several synaptic proteins at the same time, which could accelerate the screening of effective compounds for treatment of CNS disorders.

The intrinsic near-infrared photoluminescence (fluorescence) of single-walled carbon nanotubes exhibits unique photostability, narrow bandwidth, penetration through biological media, environmental sensitivity, and both chromatic variety and range. Biomedical applications exploiting this large family of fluorophores will require the spectral and spatial resolution of individual (n,m) nanotube species' fluorescence and its modulation within live cells and tissues, which is not possible with current microscopy methods. We present a wide-field hyperspectral approach to spatially delineate and spectroscopically measure single nanotube fluorescence in living systems. This approach resolved up to 17 distinct (n,m) species (chiralities) with single nanotube spatial resolution in live mammalian cells, murine tissues ex vivo, and zebrafish endothelium in vivo. We anticipate that this approach will facilitate multiplexed nanotube imaging in biomedical applications while enabling deep-tissue optical penetration, and single-molecule resolution in vivo.

Atypical fibroxanthoma (AFX) is an unusual spindle cell tumor occurring on actinically damaged skin of the head and neck. Clinically, it is often confused with basal cell carcinoma, squamous cell carcinoma, or even melanoma. Although initially thought to be a diagnosis of exclusion histologically, newer immunostains have helped in the identification of AFX. Mohs micrographic surgery has been utilized for the treatment due to its tissue sparing ability along with lower recurrence rate.

The effect of additional doping of charge impurities was investigated in a ferromagnetic semiconductor Zn1-xCrxTe. It was found that the doping of iodine, which is expected to act as an n-type dopant in ZnTe, brought about a drastic enhancement of the ferromagnetism in Zn1-xCrxTe, while the grown films remained electrically insulating. In particular, at a fixed Cr composition of x=0.05, the ferromagnetic transition temperature TC increased up to 300 K at maximum due to the iodine doping from TC=30 K of the undoped counterpart, while the ferromagnetism disappeared due to the doping of nitrogen as a p-type dopant. The observed systematic correlation of ferromagnetism with the doping of charge impurities of both the p and n type, suggesting a key role of the position of Fermi level within the impurity d state, is discussed on the basis of the double-exchange interaction as a mechanism of ferromagnetism in this material.