Anomalous Band Research Articles

Anomalous Hall conductivity and electronic structures of Si-substituted Mn2CoAl epitaxial films

We study anomalous Hall conductivity ($\sigma$$_{\rm AHC}$) and electronic band structures of Si-substituted Mn$_{2}$CoAl (Mn$_{2}$CoAl$_{1-x}$Si$_{x}$). First-principles calculations reveal that the electronic band structure is like a spin-gapless system even after substituting a quaternary element of Si for Al up to $x = $0.2 in Mn$_{2}$CoAl$_{1-x}$Si$_{x}$. This means that the Si substitution enables the Fermi level shift without largely changing the electronic structures in Mn$_{2}$CoAl. By using molecular beam epitaxy (MBE) techniques, Mn$_{2}$CoAl$_{1-x}$Si$_{x}$ epitaxial films can be grown, leading to the systematic control of $x$ (0 $\le$ $x$ $\le$ 0.3). In addition to the electrical conductivity, the values of $\sigma$$_{\rm AHC}$ for the Mn$_{2}$CoAl$_{1-x}$Si$_{x}$ films are similar to those in Mn$_{2}$CoAl films shown in previous reports. We note that a very small $\sigma$$_{\rm AHC}$ of $\sim$ 1.1 S/cm is obtained for $x =$ 0.225 and the sign of $\sigma$$_{\rm AHC}$ is changed from positive to negative at around $x =$ 0.25. We discuss the origin of the sign reversal of $\sigma$$_{\rm AHC}$ as a consequence of the Fermi level shift in MCA. Considering the presence of the structural disorder in the Mn$_{2}$CoAl$_{1-x}$Si$_{x}$ films, we can conclude that the small value and sign reversal of $\sigma$$_{\rm AHC}$ are not related to the characteristics of spin-gapless semiconductors.

The Madden–Julian oscillation during the 2016 summer and its possible impact on rainfall in China

ABSTRACTThe summer rainfall in China in 2016 exhibited a substantial intraseasonal feature, with an intensification in June and July but a suppression in August over the Yangtze River Basin and North China. The Madden–Julian oscillation (MJO) during the summer and its impact on rainfall in China are investigated by conducting observational analyses and diagnostic linear baroclinic model (LBM) experiments. A significant MJO activity in the summer is observed with three MJO episodes corresponding to three stages of rainfall in China. The LBM is utilized to diagnose the circulation response to the tropical heating forcing associated with each MJO episode. The results suggest that much of the atmospheric circulation linked to the anomalous rainfall is attributed to the strong MJO episodes. During June–July (August), the enhanced (suppressed) convection over the tropical Indian Ocean along with the suppressed (enhanced) convection over the South China Sea (SCS) to the western Pacific excite an ‘East Asian–Pacific’ north‐eastward‐propagating Rossby wave train, inducing anomalous low‐level anticyclonic (cyclonic) flows over the northern SCS and the western North Pacific but cyclonic (anticyclonic) flows over North China. They lead to a westward (eastward) shift and strengthening (weakening) of the western Pacific subtropical high, thus favouring the intensification (suppression) in rainfall over the Yangtze River Basin and North China along with the opposite variation over South China. Relative to the first MJO episode, the MJO convection in the second episode causes a northward movement of the anomalous rainfall band from the Yangtze River Basin to North China. Apart from the impact on the above regions, the first (second and third) MJO episode favours an increase (reduction) in rainfall over Northeast China.

Anomalous Pulmonary Artery Membrane: A Rare Membrane Obstructing Right Pulmonary Artery Orifice

Different types of anomalous bands, membrane, tendon, and venous valves have been described in the heart, but not within the great arteries of the heart. Here, we present a 3-year-old female child diagnosed to have a crescentic membrane originating from the superior8211;posterior wall of the pulmonary artery (PA) at bifurcation and obstructing the orifice of right PA producing significant gradient across the artery. Histopathology of this membrane showed fibrous tissue, and possibly this could be a membranous fold forming at the bifurcation of PA during the development of branch pulmonary arteries from the sixth aortic arch.

Quasiparticles and charge transfer at the two surfaces of the honeycomb iridate Na2IrO3

Direct experimental investigations of the low-energy electronic structure of the Na$_2$IrO$_3$ iridate insulator are sparse and draw two conflicting pictures. One relies on flat bands and a clear gap, the other involves dispersive states approaching the Fermi level, pointing to surface metallicity. Here, by a combination of angle-resolved photoemission, photoemission electron microscopy, and x-ray absorption, we show that the correct picture is more complex and involves an anomalous band, arising from charge transfer from Na atoms to Ir-derived states. Bulk quasiparticles do exist, but in one of the two possible surface terminations the charge transfer is smaller and they remain elusive.

Anomalous dispersion of microcavity trion-polaritons

A study of the strong coupling of different exciton species in two-dimensional molybdenum diselenide in a cavity uncovers the rich many-body physics and may lead to new devices. The strong coupling of excitons to optical cavities has provided new insights into cavity quantum electrodynamics as well as opportunities to engineer nanoscale light–matter interactions1,2,3,4,5,6. Here we study the interaction between out-of-equilibrium cavity photons and both neutral and negatively charged excitons, by embedding a single layer of the atomically thin semiconductor molybdenum diselenide in a monolithic optical cavity based on distributed Bragg reflectors. The interactions lead to multiple cavity polariton resonances and anomalous band inversion for the lower, trion-derived, polariton branch—the central result of the present work. Our theoretical analysis reveals that many-body effects in an out-of-equilibrium setting result in an effective level attraction between the exciton-polariton and trion-polariton accounting for the experimentally observed inverted trion-polariton dispersion. Our results suggest a pathway for studying interesting regimes in quantum many-body physics yielding possible new phases of quantum matter7,8,9,10,11 as well as fresh possibilities for polaritonic device architectures12,13,14,15.

Imaging Findings of the Unusual Presentations, Associations and Clinical Mimics of Acute Appendicitis.

There are many kinds of unusual presentations or associations and clinical mimics of acute appendicitis, and definitive diagnosis requires knowledge of the imaging findings in some cases. The unusual presentations and associations of acute appendicitis included in this study are perforated appendicitis, acute appendicitis occurring in hernias, acute appendicitis with cystic endosalpingiosis, intussusception of appendix, and acute appendicitis with pregnancy. We also present uncommon gastrointestinal, urinary and gynecologic clinical mimics of acute appendicitis including anomalous congenital band, duplication cysts, giant Meckel's diverticulitis, inflammatory fibroid polyp, renal artery thrombosis, spontaneous urinary extravasation and OHVIRA syndrome. Familiarity with these entities may improve diagnostic accuracy and enable the quickest and most appropriate clinical management.

Electronic excitation induced anomalous band gap enhancement in NixCd1-xO thin films

The effect of swift heavy ion(SHI) (Ag, O ion) irradiation on structural, electrical, optical properties, electron-LO phonon interaction and orbital hybridization for Ni doped CdO (NDO) based thin films has been thoroughly investigated in the present manuscript. The anomalous band gap enhancement has been explained in the frame work of electron-electron interaction, electron-impurity interaction, electron–phonon interaction and p-d hybridization between O 2p and Cd/Ni d orbitals for (NDO). The carrier concentration increment via generation of oxygen vacancies further enhances the aforementioned interaction but weakens the electron-LO phonon coupling due to screening among free carriers which counter renormalizes the band gap modification. The tensile strain observed from XRD pattern enhances the p-d hybridization which will enhance the band edge electron effective mass and subsequently the band gap. An energy band diagram has been developed to substantiate the same. However the study of the effect of EEs on hybridization is rare in the literature. Thus it emerges out to be very fascinating for the in-depth understanding of fundamental interaction besides their possible potential applications in the flourishing of optoelectronic industry.

Excited-State Proton Transfer of Cyanonaphthols in Protic Ionic Liquids: Appearance of a New Fluorescent Species.

Excited-state proton transfer (ESPT) of 5-cyano-2-naphthol (5CN2) and 5,8-dicyano-2-naphthol (DCN2) in three different protic ionic liquids (PILs), triethylammonium trifluoromethanesulfonate ([N222H][CF3SO3]), triethylammonium methanesulfonate ([N222H][CH3SO3]), and triethylammonium trifluoroacetate ([N222H][CF3COO]), was studied by time-resolved fluorescence. In [N222H][CF3SO3], both 5CN2 and DCN2 showed fluorescence only from ROH* (normal form of substituted naphthol in the excited states), indicating that no ESPT occurred in [N222H][CF3SO3]. For 5CN2 in [N222H][CH3SO3], fluorescence bands from ROH* and RO-* (anionic form of substituted naphthol in the excited states) were observed, indicating that 5CN2 could dissociate proton to surrounding solvents and form RO-*. More interestingly, 5CN2 in [N222H][CF3COO] and DCN2 in [N222H][CH3SO3] and [N222H][CF3COO] showed an anomalous fluorescence band around 470 nm (5CN2) or around 520 nm (DCN2) which has not been reported previously. The kinetics of each fluorescent component of 5CN2 and DCN2 was analyzed on the basis of the time profile of fluorescence intensity. Plausible ESPT schemes of 5CN2 and DCN2 were discussed on the basis of the kinetics and the basicity of anion in PILs.

WSe2-contact metal interface chemistry and band alignment under high vacuum and ultra high vacuum deposition conditions

Contact metals (Au, Ir, and Cr) are deposited on bulk WSe2 under ultra-high vacuum (UHV, 1 × 10−9 mbar) and high vacuum (HV, 5 × 10−6 mbar) conditions and subsequently characterized with x-ray photoelectron spectroscopy (XPS) to elucidate the effects of reactor base pressure on resulting interface chemistry, contact chemistry, and band alignment. Au forms a van der Waals interface with WSe2 regardless of deposition chamber ambient. In contrast, Ir and Cr form a covalent interface by reducing WSe2 to form interfacial metal selenides. When Cr is deposited under HV conditions, significant oxygen incorporation is observed resulting in the thermodynamically favorable formation of tungsten oxyselenide and a substantial concentration of CrxOy. Regardless of contact metal, WOx (2.63 < x < 2.92) forms during deposition under HV conditions which may positively affect interface transport properties. Cr and Ir form unexpectedly large electron and hole Schottky barriers, respectively, when deposited under UHV conditions due to interfacial reactions that contribute to anomalous band alignment. These results reveal the true interface chemistry formed between metals and WSe2 under UHV and HV conditions and demonstrate the impact on the Fermi level position following contact formation on WSe2.

Anomalous muscle bundle in the right atrium; Implication to trans atrial device closure

Intracavitary muscle bands or aberrant bands have been well described in all four chambers of the heart but rarely seen thick muscular band crossing right atrium. We report a case of devisable secundum atrial septal defect with an intra-atrial anomalous muscular band, crossing right atrial wall to the rim of the secundum atrial septal defect warranting surgical closure.

Anomalous shear band characteristics and extra-deep shock-affected zone in Zr-based bulk metallic glass treated with nanosecond laser peening

The effects of nanosecond laser peening on Zr41Ti14Cu12.5Ni10Be22.5 metallic glass were investigated in this study. The peening treatment produced an extra-deep shock-affected zone compared to crystal metal. As opposed to the conventional shear bands, numerous arc shear bands appeared and aggregated in the vertical direction of the laser beam, forming basic units for accommodating plastic deformation. The arc shear bands exhibited short and discrete features near the surface of the material, then grew longer and fewer at deeper peened layer depths, which was closely related to the laser shock wave attenuation. An energy dissipation model was established based on Hugoniot Elastic Limit and shear band characteristics to represent the formation of an extra-deep shock-affected zone. The results presented here suggest that the bulk modification of metallic glass with a considerable affected depth is feasible. Further, they reveal that nanosecond laser peening is promising as an effective approach to tuning shear bands for improved MGs ductility.

Surface and bulk electronic structures of heavily Mg-doped InN epilayer by hard X-ray photoelectron spectroscopy

To evaluate the polarity, energy band diagram, and oxygen (O) distribution of a heavily Mg-doped InN (InN:Mg+) epilayer with a Mg concentration of 1.0 ± 0.5 × 1020 cm−3, the core-level and valence band (VB) photoelectron spectra are investigated by angle-resolved soft and hard X-ray photoelectron spectroscopies. The InN:Mg+ epilayers are grown by radio-frequency plasma-assisted molecular beam epitaxy. In this doping level, the polarity inversion from In-polar to N-polar occurs with the increase in the Mg flow rate under the same growth conditions, and the VB spectrum clearly indicates the direction of polarity of InN:Mg+, which is N-polar. The energy band diagram is considered to exhibit a two-step downward bending structure due to the coexistence of the n+ surface electron accumulation layer and heavily Mg-doped p+ layer formed in the bulk. The O concentration rapidly increases until ∼4 nm with respect to the surface, which is deduced to be one of the reasons of the formation of the anomalous two-step energy band profile.

Congenital anomaly band, a rare cause of intestinal obstruction in children. Case report

Abstract Background Intestinal obstruction in children may be congenital, acquired, intrinsic or extrinsic. Most intestinal obstructions in children are the result of postoperative adhesions. Those caused by anomalous congenital band are extremely rare. Clinical case Patient of a 1-year-old male, with no previous history of abdominal surgery or trauma. He suffered with vomiting of bile content and loss of appetite at home three days before admission. On physical examination, he was irritable, with abdominal distention, absence of peristalsis and abdominal tenderness, with no signs of peritoneal irritation being found. The blood count reported leucocytosis and the x-rays show dilated small bowel loops, fluid levels and absence of air in rectal ampulla. An open laparotomy was subsequently performed, and the intraoperative findings were consistent with a congenital band extending from the anti-mesenteric wall of the jejunum to the root of mesentery, compressing the ileum at 50 cm from the ileocecal valve, causing ischaemia. The band was ligated and divided, with an uneventful postoperative course. He was discharged 4 days later without complications. Conclusions The anomalous congenital band is not associated with abdominal problems, such as remnants of previous laparotomies or embryological structures, such as vitelline vessels or omphalomesenteric yolk duct. These bands seem to have a congenital origin and cause bowel obstruction by trapping between the band and the mesentery. The diagnosis of anomalous congenital band is extremely difficult and no imaging study is useful for the diagnosis, and only exploratory laparotomy or laparoscopy is useful for diagnosis and treatment of this problem.

Effect of Reflex Neuromodulation on an Infant with Severe Amniotic Band Syndrome: A Case Report on the Use of MNRI Techniques for Physical Therapy

Introduction: MNRI offers non-invasive neuromodulating techniques to activate reflex patterns which awaken the body’s natural resources and support functioning of sensory, motor, and cognitive systems. Amniotic band syndrome (ABS) is a rare congenital disorder attributed to the anomalous amniotic bands that entangle fetal parts during intrauterine life leading to a wide range of physical abnormalities in a newborn infant, in this case, located at the superior third portion of the right arm. Due to the severity of the constricting band observed and assessed at birth, the microvascular surgeon opted for immediate post-birth surgery and Occupational and Physical Therapies were respectively initiated at 8 and 10 weeks post-surgery. Objective: This article describes early physical therapy intervention (post-surgery) using the MNRI method and discusses the effectiveness of MNRI techniques in the recovery of arm function. Results: Early intervention using the MNRI neuromodulation techniques with ABS disorder demonstrated unique and faster motor milestones development including voluntary motor and cognitive control of the immobile limb in an infant with the ABS. Summary: The use of the ready patterns of the brain-primary inherent reflexes-can be a key method and an important cornerstone for professionals to build upon for infants with the ABS.

Ultrasonographic Identification of Fibromuscular Bands Associated with Neurogenic Thoracic Outlet Syndrome: The “Wedge-Sickle” Sign

Thoracic outlet syndrome (TOS) is a disorder characterized by compression of the lower trunk of the brachial plexus, most often in association with anomalous congenital fibromuscular bands in the scalenic region. Early diagnosis is important, because the neurologic deficit associated with TOS may be irreversible. Using high-resolution ultrasound, we investigated 20 consecutive patients with clinical signs suggestive of TOS (all females, average age: 40.4 ± 14.9 y) and 25 control patients. In 19 patients, we identified a hyper-echoic fibromuscular structure at the medial edge of the middle scalene muscle, which indented the lower trunk of the brachial plexus (“wedge-sickle sign”). It was associated with the significant enlargement (p < 0.0001) and hypo-echogenicity of the lower trunk. This novel and distinctive ultrasonographic sign allows pre-surgical identification of anomalous fibromuscular bands causing TOS. It is especially useful in patients without neurologic deficit, in whom the diagnosis may not be as straightforward.

Broadband luminescence of Cu nanoparticles fabricated in SiO2 by ion implantation

In this study, we investigate optical properties of metal nanoparticle crystals fabricated by implanting copper (Cu) ions into single silica (SiO2) crystals with 400keV at various ion doses. The Cu implanted SiO2 (SiO2:Cu) crystal produces a broadband luminescence emission, ranging from blue to yellow, and having a blue luminescence peak at 546nm. Such anomalous luminescence emission bands suggest that the ion implantation may give rise to aggregation of Cu nanoparticles in the host matrix. The boundary element method-based modelling of a given Cu nanoparticle aggregation was employed to justify the broadband luminescence emission. Formation of Cu nanoparticles in SiO2 is predicted through their optical absorption data. The experimental results are compared with results of Mie calculations and we observe that the higher ion dose produces the larger particle size.

Strain induced phase formation, microstructural evolution and bandgap narrowing in strained TiO2 nanocrystals grown by ball milling

Band gap narrowing in metal oxide semiconductor nanostructures is important and advantageous for various potential applications including visible light photocatalysis. We present a systematic study on the anomalous strain evolution, phase change and band gap narrowing in TiO2 nanocrystals (NCs) as a result of ball milling. In addition to the size reduction and strain evolution with milling time, we report the formation of a new phase of TiO2 with milling, as identified in the XRD pattern and Raman spectra for the first time. Besides the tetragonal anatase phase of TiO2 NCs, two additional peaks centered at 2θ = 31.28° and 41.60° evolve with milling, and it corresponds to the (1¯ 12) and (312) planes of Ti3O5, respectively. Further, our results show that the band gap of TiO2 NCs reduces with increasing strain and lowest band gap achieved in strained TiO2 is 2.71 eV, consistent with a recent theoretical calculation. The evolution of the crystallite size, strain, stress and energy density was evaluated from the line shape analysis of the XRD pattern using various models, such as uniform deformation model, uniform stress deformation model, uniform deformation energy density model and the results are compared with those obtained directly from HRTEM analyses. The increased d-spacing with milling time was attributed to the tensile strain in TiO2 NCs. Direct evidence of lattice strain and strain relaxation is provided from HRTEM imaging and differential scanning calorimetry analyses. Our results demonstrate strain engineering of TiO2 to achieve narrow bandgap in anatase TiO2 NCs, which are promising for visible light photocatalytic and other emerging applications.

Anomalous band inversion protected by symmetry in a topological insulator of the Kane-Mele model

Depositing Au on a graphene derivate, which involves substituting four C atoms with three N atoms in a $3\times 3$ cell graphene, we realized a topological insulator of the Kane-Mele model with a gap of 50~meV surrounding the Dirac point of graphene. In this material, we observed an anomalous band inversion (BI) protected by the symmetry with character $e$ of group C$_{\rm 3V}$. The symmetry constrains two $e$ bands with mirror-symmetry combination (MSC) and mirror-antisymmetry combination (MAC) of Au and N orbitals degenerate at $\Gamma$, whereas the interaction of $\pi^*$ of graphene on the $e$-MAC band tends to lift this degenerate, resulting in that the $\pi^*$ and $e$-MAC band exchange their orbital components near $\Gamma$, causing thus a discontinued BI.

Small Bowel Obstruction due to Anomalous Congenital Bands in Children.

Introduction. The aim of the study was to evaluate our children who are operated on for anomalous congenital band while increasing the awareness of this rare reason of intestinal obstruction in children which causes a diagnostic challenge. Patients and Methods. We retrospectively reviewed the records of fourteen children treated surgically for intestinal obstructions caused by anomalous congenital bands. Results. The bands were located between the following regions: the ascending colon and the mesentery of the terminal ileum in 4 patients, the jejunum and mesentery of the terminal ileum in 3 patients, the ileum and mesentery of the terminal ileum in 2 patients, the ligament of Treitz and mesentery of the jejunum in one patient, the ligament of Treitz and mesentery of the terminal ileum in one patient, duodenum and duodenum in one patient, the ileum and mesentery of the ileum in one patient, the jejunum and mesentery of the jejunum in one patient, and Meckel's diverticulum and its ileal mesentery in one patient. Band excision was adequate in all of the patients except the two who received resection anastomosis for intestinal necrosis. Conclusion. Although congenital anomalous bands are rare, they should be considered in the differential diagnosis of patients with an intestinal obstruction.

Unusual case of an anomalous congenital band causing acute small bowel obstruction in a case of abdominal tuberculosis

Unusual case of an anomalous congenital band causing acute small bowel obstruction in a case of abdominal tuberculosis