Transverse Branch Research Articles

First-principles studies of lattice dynamics and thermal properties of Mg2Si1−xSnx

Abstract

Optical properties of Mn doped ZnO films and wires synthesized by thermal oxidation of ZnMn alloy

Mn doped ZnO films and wires, having different manganese concentrations were synthesized by thermal oxidation of the corresponding ZnMn alloy films and wires electrodeposited on a gold substrate. Structural and optical properties were addressed with scanning electron microscopy, X-ray diffraction (XRD), Raman scattering and photoluminescence (PL). To estimate the manganese concentration in Mn doped ZnO films, X-ray photoelectron spectroscopy was used. XRD patterns indicate that the incorporation of Mn2+ ions into the Zn2+ site of ZnO lattice takes place. Quenching of the ZnO PL appears due to Mn2+ ions in the ZnO lattice. Moreover, a significant decrease in the green emission of ZnO is reported in the case of the Mn doped ZnO wire array with a Mn concentration of 1.45%. The wurtzite ZnO has a total of 12 phonon modes, namely, one longitudinal acoustic (LA), two transverse acoustic (TA), three longitudinal optical (LO), and six transverse optical branches. Compared to the undoped ZnO, a gradual up-shift of the Raman lines assigned to the 2LA and A1 (LO) vibrational modes, from 482 and 567cm−1 to 532 and 580cm−1, respectively, takes place for the Mn doped ZnO films having a Mn concentration between 2 and 15%. Additionally, in the case of the Mn doped ZnO films with 7 and 15% Mn concentration, Raman spectra show the appearance and increase in the relative intensity of the ZnO Raman line assigned to the TA+LO vibrational mode in the 600–750cm−1 spectral range. For the Mn-doped ZnO wires, the presence of the Raman line peaking at 527cm−1 confirms the insertion of Mn2+ ions in ZnO lattice.

A novel combination flap of anterolateral thigh flap (ALT) and rectus femoris flap for perineal defects

The pedicled anterolateral thigh flap (ALT) has gained importance in perineal reconstruction. Especially, the combination with muscle tissue, in the form of a chimeric flap, has clearly increased its versatility and range of application. Thus, both the skin paddle and the muscle seal, filling the dead space within the small pelvis, can be used to exactly reconstruct the defect. Nevertheless, the lateral circumflex femoral artery system is known for its vascular variability. We report a case, where we planned to close a perineal defect with a combination flap of vastus lateralis muscle and ALT flap. However, the ALT was found perfused by vessels perforating the rectus femoris muscle instead of the vastus lateralis, which gained its main perfusion by the transverse branch of the lateral circumflex femoral artery. Thus, the defect was successfully reconstructed with a combination flap of ALT and rectus femoris muscle tissue. The variable anatomy of the lateral circumflex femoral artery system is one of the main challenges of the ALT flap, frequently demanding creativity and the usage of freestyle flap design. Therefore, it is possible to make a virtue out of necessity.

Dispersion relation governing the propagation of wave pulses in a mixture of interacting longitudinal and transverse phonon gases

The investigations by Koreeda et al. (2009) and Ma (2013) of the effect of second sound in dielectric crystals assume the representation of the phonon system as a mixture composed of the gas of longitudinal phonons and the gas of transverse phonons. The theoretical background of those investigations can be related either to linear phonon gas hydrodynamics based on the moment equations of Dreyer and Struchtrup (1993) or to the heuristic model of energy transport in a phonon gas proposed by Rogers (1971). The relationship between these two approaches is analyzed. Specifically, restricting attention to the one-dimensional flows, the system of linear hyperbolic equations of six-moment phonon gas hydrodynamics is discussed together with the ‘equivalent’ system of two coupled third-order in time partial differential equations for the energy densities of longitudinal and transverse phonon branches. Given the six-moment system and its equivalent, the dispersion relation governing the propagation of complex plane harmonic waves is studied in detail. It is demonstrated that the interaction between the longitudinal phonon gas and the transverse phonon gas plays an important role when determining how the complex wave number depends on the real angular frequency of plane harmonic waves. The derived dispersion relation is systematically compared with that postulated by Ma (2013). Using the principle of superposition and the real plane harmonic waves as a basis, the manifestly real pulse-like solution to the equations of phonon hydrodynamics is explicitly constructed. It is shown that the computed energy-pulse profiles have the features that agree well with the main features of the energy or temperature profiles observed in the heat-pulse experiments.

RF design and tests on a broadband, high-power coaxial quadrature hybrid applicable to ITER ICRF transmission line system for load-resilient operations

RF design and network analyzer tests of broadband, amplitude-balanced coaxial hybrid junctions are presented. We have designed two 3dB hybrid splitters with 9 and 12in. coaxial transmission lines applicable to ITER ICRF for load-resilient operations using ANSYS HFSS. Amplitude-balanced broadband responses were obtained with the combination of impedance reductions of longitudinal and transverse branches in unequal proportion, length change of 50Ω lines and diameter change of high impedance lines connected transversely to the T-section of the hybrid splitter, respectively. We have fabricated and RF tested the 9in. coaxial hybrid coupler. We obtained an excellent coupling flatness of −3.2±0.2dB, phase difference of 4 degrees and return loss of 16dB in 40–55MHz. The measured data of 9in. hybrid splitter is highly consistent with HFSS simulations. We found that the proposed 3dB hybrid splitter can be tunable with amplitude-balanced, broadband response by changing dielectric insulators to keep the inner and outer conductors of coaxial line apart. The proposed 3dB hybrid splitter can be utilized for load-resilient operations in a wide range of antenna load variations due to mode transitions or edge localized modes (ELMs) in fusion plasmas.

Phonon Transport Characteristics in a Thin Silicon Film

Phonon transport characteristics in thin silicon film are investigated due to temperature disturbance at the film edges. Phonon intensity distribution ratio , where Iomax is the maximum equilibrium intensity, I is the phonon intensity corresponding to acoustics branch at any location and time in the film) and phonon wavelength ratio , where k is the wavenumber, , and kcutoff is the cutoff wavenumber based on the film length, are introduced to assess the effects of quasi-ballistic and ballistic phonons on the film thermal conductivity and specific heat. It is found that phonon intensity ratio due to longitudinal acoustic branch is considerably higher than that of transverse acoustics branch. The influence of phonon wavelength ratio is not significantly high on the intensity ratio due to longitudinal acoustics branch. Reducing the wavelength ratio creates the size effect in the film while lowering thermal conductivity and specific heat of the film, which is more pronounced when the reduction becomes more than 20%.

The role of low-lying optical phonons in lattice thermal conductance of rare-earth pyrochlores: A first-principle study

Rare-earth pyrochlores, commonly exhibiting remarkably low lattice thermal conductivities, are considered as promising topcoat materials for thermal barrier coatings. However the structural origin underlying their low thermal conductivities remains unclear. In the present study, we investigated the phonon properties of two groups of RE pyrochlores, Ln2Zr2O7 (Ln=La, Nd, Sm, Gd) and Gd2T2O7 (T=Zr, Hf, Sn, Pb) employing density functional theory and quasi harmonic approximation. Through the relaxation time approximation (RTA) with Debye model, the thermal conductivities of those RE pyrochlores were predicted, showing good agreement with experimental measurements. The low thermal conductivities of RE pyrochlores were shown to largely come from the interference between the low-lying optical branches and acoustic branches. The structural origin underlying the low-lying optical branches was then clarified and the competition between scattering processes in transverse and longitude acoustic branches was discussed.

Anatomical variability of the anterolateral thigh flap perforators: vascular anatomy and its clinical implications.

Anatomical variability of perforators of the anterolateral thigh flap has been reported. The authors introduce a classification based on the number, location, and origin of the cutaneous perforators to comprehensively illustrate their vascular patterns in hopes that unfavorable anatomical variations of the anterolateral thigh flap can be overcome in clinical applications. The authors enrolled and reviewed 110 anterolateral thigh flaps created between September of 2010 and January of 2013 for head and neck reconstruction after cancer ablation. The location of the perforators was defined by Yu's ABC system. Its corresponding origin from the descending or transverse branch of the lateral circumflex femoral artery was clarified by Shieh's vascular anatomical classification for the anterolateral thigh flap. Of the 110 flaps, a single perforator (A or B or C) was observed in 20 flaps (18.2 percent), double perforators (A + B or B + C or A + C) were observed in 59 flaps (53.6 percent), and triple perforators (A + B + C) in 31 flaps (28.2 percent). The origin of perforators was the descending branch in 76 flaps (69.1 percent), the transverse branch in 10 flaps (9.1 percent), and both descending and transverse branches in 24 flaps (21.8 percent). The authors observed 16 vascular patterns. The most common type was double perforators, with perforators B and C originating from the descending branch [n = 40 (36.4 percent)]. The clinical significance of each pattern is delineated, and surgical technical considerations are suggested according to flap requirements and types of vascular anatomy.

Low-energy phonons and superconductivity inSn0.8In0.2Te

We present neutron scattering measurements on low-energy phonons from a superconducting ($T_{c} = 2.7$~K) Sn$_{0.8}$In$_{0.2}$Te single crystal sample. The longitudinal acoustic phonon mode and one transverse acoustic branch have been mapped out around the (002) Bragg peak for temperatures of 1.7 K and 4.2 K. We observe a substantial energy width of the transverse phonons at energies comparable to twice the superconducting gap; however, there is no change in this width between the superconducting and normal states. We also confirm that the compound is well ordered, with no indications of structural instability.

Surgical treatment of severe or moderate axillary burn scar contracture with transverse island scapular flap and expanded transverse island scapular flap in adult and pediatric patients—A clinical experience of 15 cases

BackgroundAxillary burn scar contracture is common and troublesome. With the aim of restoring the function of the upper extremities, a proper local flap with minor damage and preclusion from recurrence should be developed to guarantee satisfactory results. A minor webbed scar contracture was rectified by Z-plasty. However, severe or moderate contracture must be constructed by a local flap. An island scapular flap has been used in pediatric patients for repairing axillary contracture. However, no detailed description of the use of a transverse island scapular flap (TISF) was reported to correct the deformity. Moreover, an expanded transverse island scapular flap (ETISF) used for increasing the volume of skin for severe axillary contracture in adults and developing children was also not presented. MethodsFrom 2006 to 2013, TISFs were harvested for 12 pediatric patients (5–12 years of age) with 15 sides of severe or moderate axillary burn scar contractures. Four ETISFs were designed for two adult patients (38 and 32 years of age). The flap size was between 10cm×5cm and 20cm×10cm. In one pediatric patient, a cicatrix was observed on the surface of the flap's donor site. Handheld Doppler was applied to detect the pedicle. ResultsThe patients were required to lift their upper arms regularly each day after the operation. All 19 flaps survived completely. Axillary burn scar contractures were corrected successfully in 11 patients with no expander implantation. The lifting angle was enhanced considerably with 1–3 years of follow-up in the 11 patients. Only one pediatric patient with cicatrix on the donor site displayed tight skin on the back and a little restraint on the shoulder. The patient's parents were told to intensify the chin-up movement on the horizontal bar. She was in the process of a 3-month follow-up. The lifting angle was also improved significantly in the latter three cases of expander implantation although they were followed up for a short duration of 3 months. Due to poor flap design, the donor site of one adult patient was not closed directly with the help of skin grafting on the left side of her back. ConclusionsConsidering the flap's negligible level of later contracture and minimal trauma, local TISF based on the transverse branch of the circumflex scapular artery is a good choice for reconstruction of axillary burn scar contractures. If the TISF is not able to meet the demand, the expander implanted in advance can be more beneficial.

Numerical Variation in the Branches of the Lateral Circumflex Femoral Artery: Cadaveric Research

Background: The lateral circumflex femoral artery (LCF) is the major blood supply the thigh. It divides in ascending, transverse and descending branches. Knowledge of the branches of LCF is important in the anterolateral surgical flap from the thigh for skin grafting. Aim: This study was conducted to study the numerical variation in the branching pattern of the lateral circumflex femoral artery. Materials and Methods: 50 extremities from 25 cadavers (18 Male and 7 Females) were dissected. Lateral circumflex femoral artery and its branches were identified, dissected and studied for numerical variation in the branches. Results:10 types of numerical branching pattern were found in the present study. Descending pattern had the maximum type of variety. Transverse branches show minimum variations. Most common type (46%) of numerical variety in branches was one ascending, one transvers and one descending branch. Conclusion: Numerical branching pattern of the Lateral circumflex femoral artery show extensive variations. These variations in the branching pattern must be considered during skin grafting and other clinical interventions. Key words: Lateral circumflex femoral artery, branching pattern, ascending branch, transverse branch

Arthroscopy of the distal radioulnar joint

Insertion of a small joint arthroscope into the proximal and distal parts of the distal radioulnar joint (DRUJ) allows visualization of the proximal pouch of the DRUJ, the joint surfaces of the sigmoid notch and the ulnar head, the convexity of the ulnar head and the proximal ulnar-sided surface of the triangular fibrocartilage complex (TFCC). Evaluation of joint pathologies in ulnar-sided wrist pain, especially in cases without diagnostic findings in standard X-rays and MRI, suspected cartilage lesions without osteochondral changes (signs of osteoarthritis), undefined swelling of the DRUJ in suspected synovitis, removal of loose bodies and arthroscopical synovialectomy, suspected lesions of the deep part of the TFCC, respectively foveal avulsions, wear or superficial tears of the proximal TFCC and arthroscopic-assisted ulnar shortening. Significant changes of the local topographical anatomy, extensive scar formation, ulna plus variance, local infection or open wounds, affected sensibility in the area of the dorsal branch of the ulnar nerve, fractures of the sigmoid notch or the ulnar head, capsular tears causing effusion of irrigation fluid. In vertical extension of the wrist, two portals are created on the dorsal side of the DRUJ between the extensor digiti minimi and extensor carpi ulnaris tendons. Partial visualization of the ulnar head, the sigmoid notch, the proximal pouch of the DRUJ, and the proximal surface of the TFCC. Following isolated diagnostic arthroscopies immobilization of the wrist in a semicircular ulnar-sided cast for 1 week. No extensive load to the wrist for 4 weeks. Still rarely performed procedure for diagnosis and therapy of ulnar-sided wrist pain. Technically demanding with a flat learning curve and anatomy-related obstacles. A complete view of the joint is not always accessible. Rare complications are injuries of the extensor digiti minimi tendon as well as contusion or sectioning of the transverse branch of the dorsal branch of the ulnar nerve. In distinct cases this procedure offers valuable additional information about the distal radioulnar joint.

The clinical classification of sigle pedicled double island free anterolateral thigh flaps

To summarize the anatomic characteristic of sigle pedicled double island free anterolateral thigh flaps and to evaluate its application and classification. Between January 2010 and March 2013, 76 patients underwent free femoral anterolateral double island flap reconstruction of the defects in oral and maxillofacial region. Summarized the anatomic features of perforators, such as the number and origin of the perforators. According to the anatomic features and regularity of perforators, 76 cases of femoral anterolateral double island flaps were divided into 3 types: trunk type (type I), 15 cases (20%), in which the perforators of two flaps originated in descending branch and transverse branch of lateral femoral circumflex artery respectively; branch type (type II), 55 cases (72%), in which both the perforators originated in lateral femoral circumflex artery descending branch or lateral femoral circumflex artery transverse branch; bifurcation type (type III), 6 cases (8% ), in which two perforators originated in the two bifurcation of one perforator. Among the 76 cases, 75 survived and 1 showed partial necrosis. According to the anatomic features and regularity of perforators, femoral anterolateral double island flaps can be divided into 3 types: trunk type (I type), branch type (II type), bifurcation type (III type).

Adaptive-passive vibration isolation between nonrigid machines and nonrigid foundations using a dual-beam periodic structure with shape memory alloy transverse connection

This paper examines the problem of broadband vibration control of nonrigid systems employing periodic structures with tunable parameters. It investigates this by using a semi-two-dimensional model that applies a dual-beam periodic structure with transverse branches as a parameter-tunable isolator. Conventional study of vibration control problems, including the problem of vibration control by periodic structures, usually reduces systems to equivalent single- or multi-mount models with only a unidirectional translation at a mounting point. This assumption of decoupling leads to the erroneous prediction of vibratory power transmission when designing an isolator for a nonrigid system. Such a periodic structure involves the coupling of vibrations between different mounting points and different directions of motion and is therefore a reasonable simulation of the real-life problem. However, its application as a periodic isolator has not been proposed previously. The configuration of shape memory alloy (SMA) branches and non-SMA dual beams is proposed in order that this structure can effectively exploit the advantages of SMA materials, namely their significantly varying Young׳s moduli which can be tuned to adjust and widen the stop bands, and can prevent the associated limitation of hysteresis. Equations are derived governing the vibration transmitted through any number of periodic mounts between nonrigid machines and foundations. Based on the derived results, two methodologies are developed to determine the proper Young׳s moduli of the SMA branches and minimize the transmitted power. The numerical results demonstrate that the adaptive SMA branches at the proper temperatures are able to attenuate broadband vibration by adjusting the locations and broadening the widths of stop bands. With the application of a semi-two-dimensional periodic structure to broadband vibration isolation, this paper provides an approach and supporting methodologies for broadband vibration control using periodic structures.

Anharmonic effects in the thermoelectric properties of PbTe

In this work, we investigate the crystal anharmonic effects in the thermoelectric properties of n-type PbTe. The lattice thermal transport coefficient is computed by employing an isotropic continuum model for the dispersion relation for acoustic as well as optical phonon branches, an isotropic continuum model for crystal anharmonicity, and the single-mode relaxation time scheme. The electronic components of the transport coefficients in a wide temperature range are calculated using the isotropic-nearly-free-electron model, interaction of electrons with deformation potential of acoustic phonons, and the effect of the band non-parabolicity. It is found that the transverse optical branches play a major role in determining the phonon conductivity and the thermoelectric figure of merit of this material.

Phonon anomalies and superconductivity in the Heusler compound YPd2Sn

We have studied the structural and electronic properties of YPd2Sn in the Heusler structure using a generalized gradient approximation of the density functional theory and the ab initio pseudopotential method. The electronic results indicate that the density of states at the Fermi level is primarily derived from Pd d states, which hybridize with Y d and Sn p states. Using our structural and electronic results, phonons and electron-phonon interactions have been studied by employing a linear response approach based on the density functional theory. Phonon anomalies have been observed for transverse acoustic branches along the [110] direction. This anomalous dispersion is merely a consequence of the strong coupling. By integrating the Eliashberg spectral function, the average electron-phonon coupling parameter is found to be λ = 0.99. Using this value, the superconducting critical temperature is calculated to be 4.12 K, in good accordance with the recent experimental value of 4.7 K.

Étude anatomique du territoire musculaire du latissimus dorsi vascularisé par la branche transverse de l’artère thoraco-dorsale

The latissimus dorsi muscle flap is a type V according to Mathes and Nahai. It is vascularized by a proximal main pedicle represented by the thoraco-dorsal pedicle and pedicle distal accessory represented by the dorsal branches of the posterior intercostal arteries. The main thoraco-dorsal pedicle has a descending branch and a transverse branch. This anatomical study clarifies the muscular territory vascularized by the transverse branch of thoraco-dorsal artery for a secondary use after harvesting a thoraco-dorsal artery perforator flap or a muscle-sparing latissimus dorsi flap. Our study focused on ten dissections latissimus dorsi muscle taken from five fresh cadavers chest, carried out within the University Department of Anatomy. The descending branch of thoraco-dorsal artery was ligated, the transverse branch was cannulated and injected with a mixture of barium sulfate/gelatin. After freezing, a static angiotomodensitometry (3D) of each flap was performed. The average muscular surface vascularized by the transverse branch is measured at 80% (77% minimum value, maximum value 83%) of the complete latissimus dorsi muscle. Intermuscular connections between the two branches of thoraco-dorsal pedicle were shown. The use of a ipsilateral latissimus dorsi muscle is a therapeutic option after harvesting a thoraco-dorsal artery perforator flap (TAP) or a muscle-sparing latissimus dorsi flap (MSLD-flap).

Magnetic resonance frequencies of ferromagnets with partially frozen orbital momentum

The dynamics of the angular momentum of ferromagnets is discussed with the crystal field and the spin-orbital interaction taken systematically into account. The spectrum of the magnetic oscillations of this kind of magnet contains three branches of oscillations of different types, one of which is longitudinal oscillations in the magnitude of the orbital momentum while the other two are transverse branches corresponding to coupled oscillations of the spin and orbital momentum components.

Analysis of vibrational properties of C-doped hexagonal boron nitride (h-BN)

We present a systematic theoretical investigation of the vibrational properties of C-doped single layer hexagonal boron nitride (h-BN). Our studies have been carried out by the forced vibrational method, which is based on the idea of mechanical resonance and efficient for very complex and large system. We have estimated the phonon density of states (PDOSs) of h-BCN network with random and regular distribution of C atoms. It is found that the PDOS greatly depends on the C distribution and coverage. For randomly distributed C atoms, we observe that the longitudinal and the transverse optical (LO) and (TO) phonon branches for in-plane motion are nondegenerate at the Γ-point of the Brillouin zone. We determine a critical value of C concentration for the onset of this C-induced vibrational transition. We have found that C concentrations of about 10% and higher, the E2g peak of h-BN has been reduced into a shoulder or it has completely disappeared. For h-BCN network with regular domains of C, the PDOSs changes more abruptly. With the increase of C concentration, the high frequency optical phonons peaks above the 1400cm−1 increase linearly while the h-BN peaks below the 1400cm−1 are broadened and distorted. The disorder causes the phonon modes to be localized in the real space. Phonon localization in the hybrid BCN network is studied and the extent of localization is quantified by the typical mode pattern and the localization length. Spatial analyses of the eigenvectors using typical mode patterns show that Γ-point of the LO and TO phonon modes is strongly localized and show random behavior within a region of several nanometers in the BCN structure. In particular at 1400cm−1, a typical localization length is on the order of ≈4nm for randomly distributed C atoms and ≈8.5nm for the regular domains of C of 20% concentration, while at 1590cm−1, these values are ≈2nm and ≈4nm for randomly distributed C atoms and regular domains of C, respectively. These results are expected to stimulate further studies aimed at better understanding of the phenomena allied with vibrational properties such as thermal conductivity, specific heat capacity, and electron–phonon interaction of h-BN and BCN networks.

Phase transition of the uniaxial disordered ferroelectric Sr0.61Ba0.39Nb2O6

We report a neutron scattering study of a ferroelectric phase transition in Sr0.61Ba0.39Nb2O6 (SBN-61). The ferroelectric polarization is along the crystallographic c-axis but the transverse acoustic branch propagating along the 〈1, 1, 0〉 direction does not show any anomaly associated with this transition. We find no evidence for a soft transverse optic phonon. We do, however, observe elastic diffuse scattering. The intensity of this scattering increases as the sample is cooled from a temperature well above the phase transition. The susceptibility associated with this diffuse scattering follows the anomaly of the dielectric permittivity of SBN-61 well. Below Tc the shape of this scattering is consistent with the scattering expected from ferroelectric domain walls. Our results suggest that despite apparent chemical disorder SBN-61 behaves as a classic order-disorder uniaxial ferroelectric with critical fluctuations in the range <10−11 s.