Transverse Branch Research Articles

Lambeau libre composite ostéo-chondro-cutané de trochlée fémorale médiale dans les lésions cartilagineuses du scaphoïde et du lunatum : avantages d’une palette cutanée

A medial femoral trochlea (MFT) flap is a chondrocorticoperiosteal flap. It is a new technique described for the reconstruction of cartilage lesions. There are few descriptions of the surgical technique for harvesting this flap in its chondro-cortical form with a skin paddle. We describe and report the early results of three cases of the composite medial femoral trochlea flap, with a skin paddle. Between May 2017 and August 2017 three males were treated by a free osteochondrocutaneous graft withdraw from the medial femoral trochlea. Two cases of proximal scaphoid nonunion and one case of Kienböck disease were treated in our department. The buried osteochondroperiosteal graft was monitored on immediate postoperative oversight thanks the skin paddle, every 2 h for 5 days according to our free flap protocol. In two cases, the cutaneous pallet allowed rescue of the osteochondral flap. After 10 weeks mean postoperative, a CT scan showed complete bone healing and pins were removed. After one year follow-up, the three patients no longer had wrist pain, wrist mobility were good and patients had no discomfort in their knee. MFT flap vascularization come from the descending genicular artery (DGA) who divides into three branches: the cutaneous branch from the DGA (DGA-CB), the longitudinal periosteal branch, and the transversal periosteal branch. In about 90% of cases, a skin island flap, overlying the medial area of the knee, could be associated with the MFT flap, most often based on the DGA-CB. Associating a skin paddle is often easy and has numerous benefits such as flap monitoring, preventing vessel compression, and replacing damaged skin without high donor site morbidity. The MFT flap with a cutaneous skin paddle appears to be a safe and promising way of preventing carpal arthritis in the treatment of wrist bones nonunion or necrosis in the presence of cartilage destruction.

In Situ Reduction and Fixation of the Anterior Medial Fenestration Approach for Femoral Head Fracture.

ObjectiveTo investigate the feasibility and clinical application of the anterior medial fenestration approach in the treatment of Pipkin type I and II femoral head fractures.MethodsThe hips of two anti‐corrosion adult specimens treated with formalin were dissected and the anatomical structures and directional characteristics of the anterior medial main muscles, ligaments, blood vessels, and nerves were observed. The anterior medial fenestration approach was performed on bilateral hips of four fresh frozen specimens to determine the required pulling direction of the stripped muscles and ligaments during surgery. In addition, the vascular and nerve traction protection directions exposed in the approach were observed and analyzed. The feasibility of this approach was assessed, and the operative approach and critical anatomical depth were measured. We retrospectively analyzed 12 patients with Pipkin type I and II femoral head fractures who underwent in situ reduction and fixation by anterior medial fenestration in our hospital from February 2016 to April 2018. The study group included 3 men and 9 women aged 37–59 years (mean, 48.50 years). There were 8 cases of Pipkin type I and 4 cases of Pipkin type II. The operation time, blood loss, fracture healing time, last Thompson–Epstein evaluation, and Harris score were recorded.ResultsA total of 8 fresh frozen specimens from 4 bilateral hips were exposed by anterior medial fenestration. The upper boundary of observation fenestration was the pubic body (anterior acetabulum), and the outer upper boundary was the iliacus and the psoas muscle. The lateral boundary was the rectus femoris and the femoral vessels, while the lower boundary was the transverse branch of the medial femoral circumflex artery and vein. The medial boundary was the pubis muscle, the short adductor muscle, and the long adductor muscle. The pubofemoral and iliofemoral ligaments were observed during fenestration. By cutting open the joint capsule and moving the hip joint, the four quadrants of the femoral head can be exposed. Twelve patients with femoral head fractures who were treated with anterior medial fenestration underwent in situ reduction and fixation. The operation time was 96.25–118.75 min (median, 100 min), and the blood loss was 115.00 ± 22.76 mL. The follow‐up time was 18.58 ± 4.48 months, and the fracture healing time was 144.17 ± 14.53 days. The last Thompson–Epstein evaluation was excellent in 6 cases, good in 4 cases, and fair in 2 cases; the excellent and good rate was 83.33%. Finally, the last Harris score was 85.08 ± 5.73 points.ConclusionsThe upper and lower boundaries, inner and outer boundaries, and rear anatomical structure of the anterior medial fenestration approach were defined. The movable hip joint can expose the four quadrants in front of the femoral head in this fenestration. Anterior medial fenestration in situ reduction and fixation surgery is feasible and safe for the treatment of Pipkin type I and II femoral head fractures.

The free neurovascular transverse wrist crease flap for repairing soft tissue defects of the fingers: clinical outcomes of multiple centers

BackgroundFlap transplantation is often needed for soft tissue defects of the fingers that cannot be closed directly. Sensory reconstruction of the fingers is important for patients to recover feelings. In this study, we report clinical outcomes of using free neurovascular transverse wrist crease flap for repairing finger defects from multiple centers.MethodsThis case series includes 72 consecutive patients with finger defects between June 2013 and June 2016 from multiple centers. A neurovascular transverse free radial artery superficial palmar branch flap, named transverse wrist crease flap, was designed to reconstruct soft tissue defects of the fingers with microvascular anastomosis. When there were soft tissue defects of the fingers with digital nerve defect, end-to-end neurorrhaphy between the median palmar cutaneous branch and the digital nerves was also performed. The donor incision was sutured directly. All the patients were followed-up for more than 24 months.ResultsThe soft tissue defects of the fingers were all completely covered with this free neurovascular transverse wrist crease flap, and the flaps in 71 patients survived completely without ischemia. Vascular crisis appeared in one case, and the wound healed gradually after changing wound dressing for nearly 1 month. Slight infections of wounds appeared in eight cases. There were no complications in the donor site, like infection and poor wound healing. At the last follow-up, the mean static two-point discrimination was 9.6 ± 2.4 mm on the injured finger and 4.5 ± 0.8 on the contralateral corresponding finger. The motion range of the distal interphalangeal joint and proximal interphalangeal joint on the injured finger were 72.5 ± 23.3% and 78.7 ± 32.5% of the contralateral corresponding finger, respectively. Patient self-evaluations were good in 53 cases and fair in 19 cases.ConclusionsThe results indicate that the free neurovascular transverse wrist crease flap is a good choice for repairing soft tissue defects of the fingers.Level of evidenceTherapeutic IV

Investigating the normal state and superconducting state properties of orthorhombic and hexagonal ZrRuP: A first-principles study

We have executed ab initio pseudopotential calculations on the structural, electronic, elastic, mechanical, vibrational, and electron-phonon interaction properties of hexagonal ZrRuP (h-ZrRuP) and orthorhombic ZrRuP (o-ZrRuP). The electronic states of both phases near the Fermi energy are found to be dominated by the $d$ electrons of transition metal atoms, suggesting that they play a more active role in the generation of superconducting state for both phases of ZrRuP. A critical assessment of their elastic and mechanical properties reveals that the lattice of h-ZrRuP is softer than that of o-ZrRuP. A comparison of phonon dispersion curves for both phases indicates that the lower transverse acoustic branch of h-ZrRuP is much softer than that of o-ZrRuP. The soft character of this phonon branch gives rise to strong electron-phonon interaction in h-ZrRuP. Therefore the electron-phonon coupling parameter for h-ZrRuP equals to 1.25 which is considerably larger than the corresponding value of 0.57 for o-ZrRuP. As a consequence, phonon and electron-phonon interaction properties are crucial in making superconducting transition temperature much higher for h-ZrRuP than o-ZrRuP. At the end, the value of this temperature is found to be 12.49 K for h-ZrRuP and 3.89 K for o-ZrRuP which coincide with their experimental values of 12.93 and 3.82 K.

Anatomie de l’artère circonflexe latérale fémorale: L’abord antérieur direct de la hanche met-il en péril la vascularisation du fémur proximal?

BackgroundBlood supply of the proximal metaphysis of the femur comes mainly from the lateral circumflex femoral artery (LCFA). Essentially, the anterior approach has gained popularity in hip surgery but routinely requires the ligation of the ascending branch of the LCFA. Until now, there is no study analysing the effect of previous hip surgery on the vascularization of the proximal femur. Notably, it might, however, have consequences on osteointegration of uncemented prosthesis as well as in the management of early complications. Therefore we conducted a retrospective study to address the following questions: (1) Is the blood supply of the trochanteric region impaired by previous hip surgery, (2) does the anterior approach alter it more than other ones? HypothesisWe hypothesised that the surgical approach to the hip influences blood supply of the proximal femur, as visualised by retrospective analysis of femoral digital subtraction arteriograms (FDSA). Patients and methodsA retrospective review of 1280 FDSA, performed for vascular indications with a standard frame rate, between 07/2014 and 06/2016 in a single institution. Qualitatively sufficient FDSA were divided into 4 groups according to the history of previous hip surgery: hip replacement performed through an anterior approach (n=10) or through a lateral approach (n=31), cephalomedullary nailing for fractures of the proximal femur (n=5), and a control group of 50 continuous patients without previous hip surgery. The number of frames was counted between contrast injection into the femoral bifurcation and filling of the ipsilateral vessels of the greater trochanter to measure a potential delay/impairment of its arterial perfusion. Anatomic variations of the LCFA were also recorded. ResultsThe number of frames between contrast injection and visualisation of the blood supply of the greater trochanter was 3.6±0.9 (mean±SD) in the control group (p<0.001 vs. all other groups). In patients with a hip replacement, the delay was 7.0±1.9 frames for the anterior approach and 5.2±1.1 frames for the lateral approach, respectively. In patients after cephalomedullary nailing, a delay of 4.8±1.5 frames was measured. The delay in the anterior approach group was significantly longer (p<0.001) compared to all other investigated groups. The ascending branch of the LCFA could not be detected after the anterior approach. As after lateral approach or as in the control group, the transverse branch was detectable in approximately 2/3 of the patients. DiscussionArterial perfusion of the greater trochanter is impaired after hip surgery, particularly after an anterior approach. The clinical relevance of these findings still needs to be investigated. It might, however, explain some early aseptic failures of uncemented stems. Moreover, it should be considered in early revision surgery, because combining different approaches might critically impair femoral blood supply. Level of evidenceIII, retrospective case control study.

Mapping phonon modes from reduced-dimensional to bulk systems

A lattice-dynamics-based algorithm for mapping the true phonon modes of a film, defined by a two-dimensional (2D) Brillouin zone, to the modes of the corresponding bulk material, defined by a three-dimensional (3D) Brillouin zone, is proposed. The mapping allows for an assessment of the common assumption that film phonon modes have the same harmonic properties as the corresponding bulk phonon modes. The algorithm is based on normal mode decomposition and is inspired by the observation that the atomic trajectories generated by the 2D eigenvectors lead to standing-wave-like behaviors in the cross-plane direction. This behavior enables an unfolding scheme that does not require an assumption of cross-plane periodicity, as used in previous approaches for mapping phonon modes. The algorithm is applied to films between two and ten unit cells thick built from Lennard-Jones (LJ) argon, whose bulk is isotropic, and graphene, whose bulk (graphite) is anisotropic. For LJ argon, the density of states deviates from that of the bulk as the film gets thinner due to phonon frequencies that shift to lower values. This shift is a result of transverse branch splitting due to the film’s anisotropy and the emergence of a quadratic acoustic branch. As such, while the mapping algorithm works well for the thicker LJ argon films, it does not perform as well for the thinner films as there is a weaker correspondence between the 2D and 3D modes. For graphene, the density of states of even the thinnest films closely matches that of graphite due to the inherent anisotropy, except for a small shift at low frequencies. As a result, the mapping algorithm works well for all thicknesses of the graphene films, indicating a strong correspondence between the 2D and 3D modes.

Use of the transverse branch of the superficial circumflex iliac artery as a landmark facilitating identification and dissection of the deep branch of the superficial circumflex iliac artery for free flap pedicle: Anatomical study and clinical applications.

The deep branch of the superficial circumflex iliac artery (SCIA) should be included when a large superficial circumflex iliac artery perforator (SCIP) flap is necessary, or when anatomical structures perfused by the deep branch are procured. The aim of this study was first to describe the anatomical features of the "transverse branch" of the deep branch of the SCIA in cadavers, and then to assess the efficacy of its use as a landmark for identification and dissection of the deep branch of the SCIA through clinical applications. Twenty groin regions from 10 cadavers were dissected. The course and the takeoff point of the transverse branch were documented. With the transverse branch used as a landmark for pedicle dissection, 27 patients (16 males and 11 females) with an average age of 51.7 years underwent reconstructions that used vascularized structures nourished by the deep branch of the SCIA. Aside from the skin paddle, an iliac bone flap was used in 10 cases, a lateral femoral cutaneous nerve flap in four cases, and a sartorius muscle flap in three cases. The defect locations included the head (seven cases), the foot (six cases), the hand (six cases), the arm (five cases), and the leg (three cases). The causes of reconstruction were tumors in 13 patients, trauma in six patients, infection in four patients, surgical procedures in three patients, and refractory ulcer in one patient. In all specimens, the transverse branch was found underneath the deep fascia caudal to the anterior superior iliac spine (ASIS). The average distance from the ASIS to the transverse branch was 25.5 ± 13.0 mm (range, 5-50 mm). The average dimension of the flap was 13.1 × 5.9 cm2 . All the flaps survived completely after the surgery; lymphorrhea was seen in one patient at the donor site. The average follow-up period was 12.9 months (range, from 2 to 42 months), and all patients had good functional recovery with satisfactory esthetic results. The transverse branch was found in all specimens, branching from the deep branch of the SCIA. Successful results were achieved by using it as the landmark for identification and dissection of the deep branch of the SCIA. This method allows safe elevation of a large SCIP flap or a chimeric SCIP flap.

Body-centered-cubic structure and weak anharmonic phonon scattering in tungsten

It was recently found that the anharmonic phonon–phonon scattering in tungsten is extremely weak at high frequencies, leading to a predominance of electron–phonon scattering and consequently anomalous phonon transport behaviors. In this work, we calculate the phonon linewidths of W along high-symmetry directions from first principles. We find that the weak phonon–phonon scattering can be traced back to two factors. The first is the triple degeneracy of the phonon branches at the P and H points, a universal property of elemental body-centered-cubic (bcc) structures. The second is a relatively isotropic character of the phonon dispersions. When both are met, phonon–phonon scattering rates must vanish at the P and H points. The weak phonon–phonon scattering feature is also applicable to Mo and Cr. However, in other elemental bcc substances like Na, the isotropy condition is violated due to the unusually soft character of the lower transverse acoustic phonon branch along the Γ-N direction, opening emission channels and leading to much stronger phonon–phonon scattering. We also look into the distributions of electron mean-free paths (MFPs) at room temperature in tungsten, which can help engineer the resistivity of nanostructured W for applications such as interconnects.

Mindlin–Eringen anisotropic micromorphic elasticity and lattice dynamics representation

ABSTRACTTo account for certain essential features of material such as dispersive behaviour and optical branches in dispersion curves, a fundamental departure from classical elasticity to polar theories is required. Among the polar theories, micromorphic elasticity of appropriate grades and anisotropy is capable of capturing these physical phenomena completely. In the mathematical framework of micromorphic elasticity, in addition to the traditional elastic constants, some additional constants are introduced in the pertinent governing equations of motion. A precise evaluation of the numerical values of the aforementioned elastic constants in the realm of the experimentations poses serious difficulties. Thus this paper aims to provide a remedy as how to determine the micromorphic elastic constants theoretically in terms of the atomic force constants and lattice parameters of the crystalline solid with general anisotropy. In this treatment capture of the discrete nature of matter becomes an essential factor. To this end, the discrete lattice dynamics equations of a crystal are related to the pertinent anisotropic micromorphic equations of motion. This approach allows incorporating the symmetry groups of the crystals within lattice dynamics equations conveniently. For the illustration of the current theoretical developments, the micromorphic elastic constants of diamond and silicon crystals are computed in conjunction with ab initio density functional perturbation theory (DFPT). Moreover, the longitudinal and transverse optical and acoustic branches pertinent to [100] and [110] directions are presented. The accuracy of the results is verified by comparing the dispersion curves derived from the micromorphic theory, those of available experiments, and those directly obtained from DFPT calculations.

Anatomy of the lateral circumflex femoral artery: Does the direct anterior approach to the hip jeopardize vascularization of the proximal femur?

BackgroundBlood supply of the proximal metaphysis of the femur comes mainly from the lateral circumflex femoral artery (LCFA). Essentially, the anterior approach has gained popularity in hip surgery but routinely requires the ligation of the ascending branch of the LCFA. Until now, there is no study analysing the effect of previous hip surgery on the vascularization of the proximal femur. Notably, it might, however, have consequences on osteointegration of uncemented prosthesis as well as in the management of early complications. Therefore we conducted a retrospective study to address the following questions: (1) Is the blood supply of the trochanteric region impaired by previous hip surgery, (2) does the anterior approach alter it more than other ones? HypothesisWe hypothesised that the surgical approach to the hip influences blood supply of the proximal femur, as visualised by retrospective analysis of femoral digital subtraction arteriograms (FDSA). Patients and methodsA retrospective review of 1280 FDSA, performed for vascular indications with a standard frame rate, between 07/2014 and 06/2016 in a single institution. Qualitatively sufficient FDSA were divided into 4 groups according to the history of previous hip surgery: hip replacement through an anterior approach (n=10) or through a lateral approach (n=31), cephalomedullary nailing for fractures of the proximal femur (n=5), and a control group of 50 continuous patients without previous hip surgery. The number of frames was counted between contrast injection into the femoral bifurcation and filling of the ipsilateral vessels of the greater trochanter to measure a potential delay/impairment of its arterial perfusion. Anatomic variations of the LCFA were also recorded. ResultsThe number of frames between contrast injection and visualisation of the blood supply of the greater trochanter was 3.6±0.9 (mean±SD) in the control group (p<0.001 vs. all other groups). In patients with a hip replacement, the delay was 7.0±1.9 frames for the anterior approach and 5.2±1.1 frames for the lateral approach, respectively. In patients after cephalomedullary nailing, a delay of 4.8±1.5 frames was measured. The delay in the anterior approach group was significantly longer (p<0.001) compared to all other investigated groups. The ascending branch of the LCFA could not be detected after the anterior approach. As after lateral approach or as in the control group, the transverse branch was detectable in approximately 2/3 of the patients. DiscussionArterial perfusion of the greater trochanter is impaired after hip surgery, particularly after an anterior approach. The clinical relevance of these findings still needs to be investigated. It might, however, explain some early aseptic failures of uncemented stems. Moreover, it should be considered in early revision surgery, because combining different approaches might critically impair femoral blood supply. Level of evidenceIII, retrospective case control study.

Free graft of vascularized iliac bone flap based on deep iliac circumflex vessels for the treatment of osteonecrosis of the femoral head

Objective To investigate the feasibility and clinical efficacy of free graft of vascularized iliac bone flap based on deep iliac circumflex vessels for the treatment of osteonecrosis of femoral head (ONFH). Methods Twelve cases of ONFH (13 hips) received free graft of vascularized iliac bone flap based on deep iliac circumflex vessels from April, 2016 to July, 2017. The average Harris score was (74.7±6.9) in the second stage and (68.6±9.2) in the third stage. After debriding the necrosis bone of the femoral head, the contralateral vascularized iliac bone flap had been harvested, and then implanted into the femoral head. The deep iliac circumflex artery and its accompanying vein were anastomosed with the transverse branch (or ascending branch) of the lateral circumflex femoral artery and concomitant vein respectively. The herringbone brace was used for hip fixation for 3 weeks after operation. X-ray examination(1, 3, 6, 9 and 12 months after operation, respectively) and Harris hip score (6 and 12 months after operation, respectively) were performed to evaluate the recovery results of the femoral head. Scores were recorded and analyzed by paired t-test. The difference was considered to statistically significant if P<0.05. Results The patients were followed-up for 15 (12-20) months. The iliac bone flap of 12 patients (13 hips) healed well. There was no necrosis and collapse in 12 hips, except 1 femoral head collapsed slightly because of weight loading too early. The average Harris score was (91.6±4.5) of the second stage and (84.8±6.1) of the third stage. Compared with scores before the operation, the difference was statistically significant (P<0.05). Conclusion Free vascularized iliac bone grafting based on deep iliac circumflex vessels is an ideal treatment for ONFH head in middle and advanced stage. Key words: Osteonecrosis of the femoral head; Iliac bone flap; Deep iliac circumflex vessels; Transplantation; Harris hip score

Anomalous thermal expansion and chiral phonons in BiB3O6

The origins of anomalous thermal expansion in the chiral monoclinic solid $\alpha$-BiB$_{3}$O$_{6}$ have been studied through ab initio calculations. Positive and negative axial thermal expansion are shown to be driven by librations of borate units, elastic anisotropy, and most notably by chiral acoustic phonons involving elliptical revolutions of bismuth atoms. The chirality of the lattice gives rise to these modes by allowing the transverse acoustic branches to have opposite circular polarizations, only one of which couples strongly to the lattice strains. These results further understanding of relationships between crystallographic symmetry and physical properties.

Symmetry-Protected Ideal Type-II Weyl Phonons in CdTe.

Nontrivial low-energy excitations of crystalline solids have insightfully strengthened understanding of elementary particles in quantum field theory. Usually, topological quasiparticles are mainly focused on fermions in topological semimetals. We alternatively show by first-principles calculations and symmetry analysis that ideal type-II Weyl phonons are present in zinc-blende cadmium telluride, a well-known II-VI semiconductor. Importantly, these type-II Weyl phonons originate from the inversion between the longitudinal acoustic and transverse optical branches. Symmetry guarantees that the type-II Weyl points lie along the high-symmetry lines at the boundaries of the Brillouin zone even with a breaking of inversion symmetry, exhibiting the robustness of protected phonon features. The nontrivial phonon surface states and surface arcs projected on the semifinite (001) and (111) surfaces are investigated. The phonon surface arcs connecting the Weyl points with opposite chirality, guaranteed to be very long, are clearly visible. We not only offer a promising candidate for studying type-II Weyl phonons but also provide a route to realize symmetry-protected nontrivial phonons and related applications in realistic materials.

A comparative study of cortico-cancellous iliac bone graft with or without the combination of vascularized greater trochanter flap for the management of femoral head osteonecrosis: a minimum 6\u2009years follow-up

BackgroundTo compare the mid-long-term clinical and radiological outcomes between a combination of cortico-cancellous iliac bone graft with vascularized greater trochanter flap (Group A) and isolate iliac bone graft (Group B) in the treatment of Osteonecrosis of the Femoral Head (ONFH).MethodsFrom January 2006 to December 2012, 123 patients (135 hips) who underwent abovementioned hip-preserving surgeries were included for analysis. Clinical outcomes were assessed based on Harris Hip Score (HHS) System and The Western Ontario and McMaster University Index (WOMAC) scores between the preoperative and the last follow-up. A series of postoperative X-rays were compared to preoperative images for radiological evaluation.ResultsThe HHS in Group A and B were enhanced from 50.57 ± 3.39 to 87.60 ± 4.15 and from 50.24 ± 3.30 to 85.18 ± 6.45, respectively, which both showed significance between preoperative and postoperative latest follow-up (p < 0.001). Group A revealed better improvement in terms of HHS (p = 0.017). The WOMAC total, postoperative stiffness, difficulty subscale scores in Group A showed better outcomes when compared to Group B (p < 0.01), while pain improvement between these two groups revealed no significance (p = 0.402). Besides, Group A suggested better necrotic region repair (p = 0.020), but no femoral head collapse difference in terms of Association Research Circulation Osseous classification change was found (p > 0.05).ConclusionsA combination of cortico-cancellous iliac bone graft and concurrent vascularized greater trochanter flap with the lateral femoral circumflex transverse branch has been proved can obtain better functional and radiological results than isolate iliac bone grafting, which is attributed to blood reconstruction of the femoral head.

Hindbrain neurovascular anatomy of adult goldfish (Carassius auratus).

The goldfish hindbrain develops from a segmented (rhombomeric) neuroepithelial scaffold, similar to other vertebrates. Motor, reticular and other neuronal groups develop in specific segmental locations within this rhombomeric framework. Teleosts are unique in possessing a segmental series of unpaired, midline central arteries that extend from the basilar artery and penetrate the pial midline of each hindbrain rhombomere (r). This study demonstrates that the rhombencephalic arterial supply of the brainstem forms in relation to the neural segments they supply. Midline central arteries penetrate the pial floor plate and branch within the neuroepithelium near the ventricular surface to form vascular trees that extend back towards the pial surface. This intramural branching pattern has not been described in any other vertebrate, with blood flow in a ventriculo-pial direction, vastly different than the pial-ventricular blood flow observed in most other vertebrates. Each central arterial stem penetrates the pial midline and ascends through the floor plate, giving off short transverse paramedian branches that extend a short distance into the adjoining basal plate to supply ventromedial areas of the brainstem, including direct supply of reticulospinal neurons. Robust r3 and r8 central arteries are significantly larger and form a more interconnected network than any of the remaining hindbrain vascular stems. The r3 arterial stem has extensive vascular branching, including specific vessels that supply the cerebellum, trigeminal motor nucleus located in r2/3 and facial motoneurons found in r6/7. Results suggest that some blood vessels may be predetermined to supply specific neuronal populations, even traveling outside of their original neurovascular territories in order to supply migrated neurons.

Extraordinary reflection and refraction from natural hyperbolic materials.

The reflection and refraction were theoretically investigated for a linearly-polarized wave incident upon the surface of a naturally hyperbolic material. We proposed that this material is uniaxial and possesses two hyperbolic-frequency bands (HB-I and HB-II), whose optical axis is arbitrarily pointed. We paid our attention to reflective and refractive features in the HBs and predicted some extraordinary phenomena. The double reflection was found, where the reflective wave contains a transverse electric branch and a transverse magnetic branch with different amplitudes and phases. The asymmetry of reflection exists and the reflective coefficient abnormally decreases as the incident angle is enlarged. The double refraction inside the material means two refractive branches (the o-wave and e-wave). For the e-wave, there is a special frequency point (SP) in either HB, depending on the orientation of the optical axis. The e-wave and reflective wave exhibit completely different behaviors on the two sides of the SP. The e-wave is a normal refractive wave on the left side of the SP, but it is an evanescent wave on the right side. Its energy-flux seriously deviates from the incident plane and is highly condensed at the inner surface near the SP. It is more interesting that the energy-flux density of the e-wave in the HB-II can even be much larger than that of the incident wave and is opposite in direction on the two sides of the SP, which means an evident radiation-switching effect. The o-wave is a normal refractive wave in the HB-I, but it is an evanescent wave in the HB-II. The above results and conclusions were obtained from the hexagonal boron nitride (hBN). These unique properties may be very useful in optical or optoelectronic technology.

A Design for the Dual Skin Paddle Circumflex Scapular Artery Perforator Flap for the Reconstruction of Complex Soft-Tissue Defects in Children

The main drawbacks of the use of the circumflex scapular artery perforator (CSAP) flap for complex soft-tissue defect repair are the limitation of skin paddle size, which can be harvested to allow precise wound coverage and primary closure of the donor site. We developed a variant of the dual skin paddle CSAP flap to extend its applications and minimize donor-site morbidity when reconstructing complex soft-tissue defects in children. A detailed anatomical investigation of circumflex scapular artery (CSA) branches was conducted using a standardized injection of lead oxide in 25 fresh cadavers. Dual skin paddle CSAP flaps were harvested for the reconstruction of complex defects in the extremities in 16 children. Three types of dual skin paddle CSAP flap were used in this study: transverse chain-shaped, oblique chain-shaped, and trefoil-shaped flaps. Three CSA branching patterns with superior branch diameters were observed: 34% of CSAs were of the transverse branch dominant type, 54% were of the descending branch dominant type, and 12% were of the codominant type. Sixteen dual skin paddle CSAP flaps were elevated successfully; they were of the transverse chain-shaped type in 2 cases, the oblique chain-shaped type in 9 cases, and the trefoil-shaped type in 5 cases. All flaps survived postoperatively. Primary closure of the donor site was achieved in all cases. The CSA system is an appropriate source for harvesting dual skin paddle CASP flap. Use of this flap for the reconstruction of complex soft-tissue defects in the extremities in children is an alternative approach that reduces morbidity and improves the cosmetic outcome at the donor site.

Experimental study of overpressure evolution laws and flame propagation characteristics after methane explosion in transversal pipe networks

To explore overpressure evolution laws and flame propagation characteristics after methane explosion in a complex pipe network, we established in the lab a transversal pipe network methane explosion experimental system and experimentally studied the explosive pressure wave propagation laws of premixed gases of three different methane concentrations (8%, 9.5%, and 11%). Experimental results indicate that an overpressure rising region will be formed in the transversal branch, which is due to the superposition of pressure waves after methane–air premixed gas explosion. However, the flame intensity generated by pressure wave is extremely small and the flame sustaining time is very short. In the parallel branch, maximum explosion overpressure presents a gradually descending trend, and flame propagation velocity presents a rising and then descending trend, but the flame sustaining time decreases first, then increases, and finally decreases again as the distance from the explosion source increases. The maximum explosion overpressure and flame propagation velocity of the gas with a 9.5% methane concentration are higher than 8% and 11%. The experimental study obtains a preliminary mastery of overpressure evolution laws and flame propagation characteristics after methane explosion in pipe networks. The results could provide important theoretical guidelines for the prevention and control of fuel gas explosion in urban pipe networks.

Comment on "Giant electromechanical coupling of relaxor ferroelectrics controlled by polar nanoregion vibrations".

Manley et al. (Science Advances, 16 September 2016, p. e1501814) report the splitting of a transverse acoustic phonon branch below T C in the relaxor ferroelectric Pb[(Mg1/3Nb2/3)1-x Ti x ]O3 with x = 0.30 using neutron scattering methods. Manley et al. argue that this splitting occurs because these phonons hybridize with local, harmonic lattice vibrations associated with polar nanoregions. We show that splitting is absent when the measurement is made using a different neutron wavelength, and we suggest an alternative interpretation.

Application of a new classification of chimeric anterolateral thigh free flaps

BackgroundThe anterolateral thigh free flap is one of the most commonly used flaps in reconstructive procedures. The purpose of this study was to assess this new classification of chimeric anterolateral thigh free flaps. MethodsSixty-five patients underwent free anterolateral thigh chimeric free flap reconstruction of defects in the head and neck region. We summarized the anatomic features of perforators, including the number and origin of the perforators. ResultsSixty-five cases of femoral anterolateral double island flaps were divided into 3 types: trunk type (type I), 11 cases (16.9%), in which the perforators of two flaps originated in the descending branch and the transverse branch of the lateral femoral circumflex artery; branch type (type II), 45 cases (69.3%), in which both the perforators originated in the descending branch or the transverse branch of the lateral femoral circumflex artery; and bifurcation type (type III), 9 cases (13.8%), in which two perforators originated in the bifurcation of one perforator that originated in the descending branch or the transverse branch of the lateral femoral circumflex artery. All 65 flaps survived and none showed partial necrosis. ConclusionsThe anterolateral thigh chimeric flap can be divided into 3 types: trunk type (I type), branch type (II type) and bifurcation type (III type).