Impact of etch processes on the chemistry and surface states of the topological insulator Bi2Se3

The unique properties of topological insulators such as Bi2Se3 are intriguing for their potential implementation in novel device architectures for low power and defect-tolerant logic and memory devices. Recent improvements in the synthesis of Bi2Se3 have positioned researchers to fabricate new devices to probe the limits of these materials. The fabrication of such devices, of course, requires etching of the topological insulator, in addition to other materials including gate oxides and contacts which may impact the topologically protected surface states. In this paper, we study the impact of He+ sputtering and inductively coupled plasma Cl2 and SF6 reactive etch chemistries on the physical, chemical, and electronic properties of Bi2Se3. Chemical analysis by X-ray photoelectron spectroscopy tracks changes in the surface chemistry and Fermi level, showing preferential removal of Se that results in vacancy-induced n-type doping. Chlorine-based chemistry successfully etches Bi2Se3 but with residual Se–Se bonding and interstitial Cl species remaining after the etch. The Se vacancies and residuals can be removed with postetch anneals in a Se environment, repairing Bi2Se3 nearly to the as-grown condition. Critically, in each of these cases, angle-resolved photoemission spectroscopy (ARPES) reveals that the topologically protected surface states remain even after inducing significant surface disorder and chemical changes, demonstrating that topological insulators are quite promising for defect-tolerant electronics. Changes to the ARPES intensity and momentum broadening of the surface states are discussed. Fluorine-based etching aggressively reacts with the film resulting in a relatively thick insulating film of thermodynamically favored BiF3 on the surface, prohibiting the use of SF6-based etching in Bi2Se3 processing

A webcam-based machine learning approach for three-dimensional range of motion evaluation.

BackgroundJoint range of motion (ROM) is an important quantitative measure for physical therapy. Commonly relying on a goniometer, accurate and reliable ROM measurement requires extensive training and practice. This, in turn, imposes a significant barrier for those who have limited in-person access to healthcare.ObjectiveThe current study presents and evaluates an alternative machine learning-based ROM evaluation method that could be remotely accessed via a webcam.MethodsTo evaluate its reliability, the ROM measurements for a diverse set of joints (neck, spine, and upper and lower extremities) derived using this method were compared to those obtained from a marker-based optical motion capture system.ResultsData collected from 25 healthy adults demonstrated that the webcam solution exhibited high test-retest reliability, with substantial to almost perfect intraclass correlation coefficients for most joints. Compared with the marker-based system, the webcam-based system demonstrated substantial to almost perfect inter-rater reliability for some joints, and lower inter-rater reliability for other joints (e.g., shoulder flexion and elbow flexion), which could be attributed to the reduced sensitivity to joint locations at the apex of the movement.ConclusionsThe proposed webcam-based method exhibited high test-retest and inter-rater reliability, making it a versatile alternative for existing ROM evaluation methods in clinical practice and the tele-implementation of physical therapy and rehabilitation

Expression of a putative stem cell marker Musashi-1 in endometrium

Aim: Firstly to examine the expression characteristics of Musashi (Msi)-1 in fetal endometrium, reproductive normal endometrium, endometrial hyperplasia and endometrioid adenocarcinoma, next, to focus on exploring the possibility that Msi-1 serves as a marker of the endometrial stem cells in-situ. Methods: Immunohistochemical staining was performed to detect the expression of Msi-1 in 20 cases of fetal endometrium, 20 cases of normal endometrium, 20 cases of endometrial hyperplasia and 50 cases of endometrioid adenocarcinoma respectively. Results: In fetal endometrium, Msi-1 positive cells were observed from the 12th week in epithelium, but the number of Msi-1 positive cells decreased with an increase in gestational age. In reproductive normal endometrium, Msi-1 expression presented as dispersed single cell and cell groups in the stroma adjacent to the myometrium. In endometrial hyperplasia and endometrioid adenocarcinoma, Msi-1 expression significantly increased and was more widely distributed. Conclusions: Msi-1 positive cells mainly lie in the stroma of normal endometrium, and the distribution pattern is consistent with that of the speculated endometrial stem cells. The high expression of Msi-1 in fetal endometrium and endometrioid adenocarcinoma suggests that Msi-1 positive cells have several characteristics of stem cells, such as high proliferative potentiality and multipotency. Considering these factors, this makes Msi-1 potentially a promising stem cell marker

Social Psychology in the Task Organization of Dyadic 90° Rhythmic Coordination: The Coupling Is Not What You Might Expect

Herth, Zhu and Bingham (2021) investigated frequency scaling of a learned 90° bimanual rhythmic coordination in the context of both noninterference and correcting instructions. They found that performance of 90° coordination remained stable at high frequencies with correcting, but that performance deteriorated as frequency increased without correcting. The participants trained during learning both at performing bimanual and unimanual coordination and in both cases, they trained to the same criterion level of performance. Herth, Zhu and Bingham (submitted) then tested these same participants with frequency scaling of unimanual 90° coordination. They found in this case that the stability of performance was lost in the same way both with and without correcting. The question raised by this difference in results was whether the inability to maintain stable performance of unimanual coordination with correcting was due to the lack of kinesthetic/neural coupling or to the lack of bidirectional coupling present in bimanual coordination. To separate the two differences in coupling, frequency scaling of learned 90° coordination between two people (dyads) was tested in the current study because this was expected to isolate bidirectional coupling without the kinesthetic/neural coupling. Dyadic coordination is strictly visual. However, the results were identical to those found with unimanual coordination. The ability to correct did not yield stable performance at high frequency. An analysis was performed that showed that the coupling in the dyadic coordination was unidirectional contrary to the common expectation. Dyads were not allowed to communicate directly during learning and testing sessions, but they established the role of the coordinator and corrector vs who would just be steady state in organizing the task performance, nevertheless. Some dyads never achieved criterion performance even after over a dozen training sessions. Perchance they failed to achieve the requisite task organization. The results yielded an interesting problem in social psychology

Preparation of PVDF/Hyperbranched-Nano-Palygorskite Composite Membrane for Efficient Removal of Heavy Metal Ions

In this work, three kinds of hyperbranched polyamidoamine-palygorskite (PAMAM-Pal) were designed and synthesized by grafting the first generation polyamidoamine (G1.0 PAMAM), G2.0 PAMAM and G3.0 PAMAM onto Pal surfaces, respectively. Then, these PAMAM-Pals were used as additives to prepare polyvinylidene fluoride (PVDF)/hyperbranched polyamidoamine-palygorskite bicomponent composite membranes. The structures of the composite membranes were characterized by Fourier transform infrared spectroscopy (FTIR), thermo gravimetric analysis (TEM), X-ray photoelectron spectroscopy (XPS), field-emission scanning electronmicroscopy (SEM), atomic force microscope (AFM) and Thermogravimetric analysis (TGA). The adsorption properties of composite membranes to heavy metal ions was studied, and the results found that the maximum adsorption capacities for Cu(II), Ni(II) and Cd(II) could reach 155.19 mg/g, 124.28 mg/g and 125.55 mg/g, respectively, for the PVDF/G3.0 PAMAM-Pal membrane, while only 23.70 mg/g, 17.74 mg/g and 14.87 mg/g could be obtained for unmodified membranes in the same conditions. The high adsorption capacity can be ascribed to the large number of amine-terminated groups, amide groups and carbonyl groups of the composite membrane. The above results indicated that the prepared composite membrane has a high adsorption capacity for heavy metal ions removal in water treatment

Experience Modulates Visual Search Strategies and the Effectiveness of Information Pickup to Overcome the Inversion Effect in Biological Motion Perception

The inversion effect of biological motion suggests that presenting a point-light display in an inverted orientation would affect the observer’s ability to perceive the movement. This could be attributed to the observer’s general unfamiliarity with the dynamic characteristics of the movement after the inversion. A previous study showed that, compared to typical and non-dancers, vertical dancers were more sensitive to the artificial inversion of dance movements performed either in an upright or inverted orientation, when provided with dynamic information. This ability was attributed to vertical dancers’ unique visual and motor experience of performing movements upside down while hanging in the air. The current study aimed to replicate this finding and use eye-tracking data to identify the source of information that vertical dancers relied on to perform the judgment. Twenty dance movements were recorded either on the ground or in the air. Each pair of ground and air movements had similar forms to control the configural information. The movement was either presented as-is or inverted and the participants needed to determine whether the display was inverted. The results replicated the previous study and further showed that the higher sensitivity of vertical dancers in detecting the inverted movements was attributed to their longer and more frequent fixations on the lower torso area, where the harness was placed when performing the air movement. Although traditional dancers also attended to the lower torso area, their lack of experience with inverted movements limited their ability to interpret the observed motion for detection of the inversion

Remote Plasma Oxidation and Atomic Layer Etching of MoS₂

Exfoliated molybdenum disulfide (MoS₂) is shown to chemically oxidize in a layered manner upon exposure to a remote O₂ plasma. X-ray photoelectron spectroscopy (XPS), low energy electron diffraction (LEED), and atomic force microscopy (AFM) are employed to characterize the surface chemistry, structure, and topography of the oxidation process and indicate that the oxidation mainly occurs on the topmost layer without altering the chemical composition of underlying layer. The formation of S–O bonds upon short, remote plasma exposure pins the surface Fermi level to the conduction band edge, while the MoO_<i>x</i> formation at high temperature modulates the Fermi level toward the valence band through band alignment. A uniform coverage of monolayer amorphous MoO₃ is obtained after 5 min or longer remote O₂ plasma exposure at 200 °C, and the MoO₃ can be completely removed by annealing at 500 °C, leaving a clean ordered MoS₂ lattice structure as verified by XPS, LEED, AFM, and scanning tunneling microscopy. This work shows that a remote O₂ plasma can be useful for both surface functionalization and a controlled thinning method for MoS₂ device fabrication processes

Ars2 promotes cell proliferation and tumorigenicity in glioblastoma through regulating miR-6798-3p

Abstract Arsenic resistance protein 2 (Ars2) is a component of the nuclear RNA cap-binding complex (CBC) that is important for some microRNA biogenesis and it is critical for cell proliferation and tumorigenicity. However, mechanism of Ars2-regulated cellular proliferation and tumorigenicity in glioblastoma has not been fully understood. Western blotting was used to detect the expressions of Ars2, p53, p21, and cleavage/activation of caspases-3 (C-Caspase 3). Microarray and Quantitative Real-time PCR (qRT-PCR) were performed to identify the Ars2-regulated microRNAs. Apoptosis assessed by flow cytometry analysis was used to evaluate the role of Ars2 in cells proliferation. The lentivirus-mediated gene knockdown approach was conducted to determine the function of Ars2. The orthotopic glioblastoma xenograft was used to demonstrate the role of Ars2 in glioblastoma growth in vivo. The high expression of Ars2 was observed in several glioblastoma cell lines and was significantly associated with poorer overall survival. Importantly, the overexpression of Ars2 promoted cell proliferation and colony formation in glioblastoma cells, whereas the depletion of Ars2 inhibited cell proliferation, colony formation, and tumor growth. Mechanistic study revealed that knockdown of Ars2 reduced the expression levels of miR-6798-3p, which was responsible for the up-regulation of p53 and p21, leading to apoptosis. Furthermore, the knockdown of Ars2 suppressed tumor growth in orthotopic glioblastoma xenograft model and significantly prolonged the survival time of the tumor-bearing mice. These findings identify a critical role for Ars2 in regulation of proliferation and tumorigenicity in glioblastoma and suggest that Ars2 could be a critical therapeutic target for glioblastoma intervention