Engineering functional tissues of clinically relevant size (in mm-scale) in vitro is still a challenge in tissue engineering due to low oxygen diffusion and lack of vascularization. To address these limitations, a perfusion bioreactor was used to generate contractile engineered muscles of a 3 mm-thickness and a 8 mm-diameter. This study aimed to upscale the process to 50 mm in diameter by combining murine skeletal myoblasts (SkMbs) with human adipose-derived stromal vascular fraction (SVF) cells, providing high neuro-vascular potential in vivo. SkMbs were cultured on a type-I-collagen scaffold with (co-culture) or without (monoculture) SVF. Large-scale muscle-like tissue showed an increase in the maturation index over time (49.18 ± 1.63% and 76.63 ± 1.22%, at 9 and 11 days, respectively) and a similar force of contraction in mono- (43.4 ± 2.28 µN) or co-cultured (47.6 ± 4.7 µN) tissues. Four weeks after implantation in subcutaneous pockets of nude rats, the vessel length density within the constructs was significantly higher in SVF co-cultured tissues (5.03 ± 0.29 mm/mm2) compared to monocultured tissues (3.68 ± 0.32 mm/mm2) (p < 0.005). Although no mature neuromuscular junctions were present, nerve-like structures were predominantly observed in the engineered tissues co-cultured with SVF cells. This study demonstrates that SVF cells can support both in vivo vascularization and innervation of contractile muscle-like tissues, making significant progress towards clinical translation.
Germanium-tin nanoparticles are promising materials for near- and mid-infrared photonics thanks to their tunable optical properties and compatibility with silicon technology. This work proposes modifying the spark discharge method to produce Ge/Sn aerosol nanoparticles during the simultaneous erosion of germanium and tin electrodes. Since tin and germanium have a significant difference in the potential for electrical erosion, an electrical circuit damped for one period was developed to ensure the synthesis of Ge/Sn nanoparticles consisting of independent germanium and tin crystals of different sizes, with the ratio of the atomic fraction of tin to germanium varying from 0.08 ± 0.03 to 0.24 ± 0.07. We investigated the elemental and phase composition, size, morphology, and Raman and absorbance spectra of the nanoparticles synthesized under different inter-electrode gap voltages and the presence of additional thermal treatment directly in a gas flow at 750 °C. The research shows that the in-flow thermal treatment of aerosol-agglomerated nanoparticles produced special individual bicrystalline Janus Ge/Sn nanoparticles with an average size of 27 nm and a decreasing absorption function with a changing slope at 700 nm.
The maximum recoverable strain of most crystalline solids is less than 1% because plastic deformation or fracture usually occurs at a small strain. In this work, we show that a SrNi2P2 micropillar exhibits pseudoelasticity with a large maximum recoverable strain of â¼14% under uniaxial compression via unique reversible structural transformation, double lattice collapse-expansion that is repeatable under cyclic loading. Its high yield strength (â¼3.8 ± 0.5 GPa) and large maximum recoverable strain bring out the ultrahigh modulus of resilience (â¼146 ± 19 MJ/m3), a few orders of magnitude higher than that of most engineering materials. The double lattice collapse-expansion mechanism shows stress-strain behaviors similar to that of conventional shape-memory alloys, such as hysteresis and thermo-mechanical actuation, even though the structural changes involved are completely different. Our work suggests that the discovery of a new class of high-performance ThCr2Si2-structured materials will open new research opportunities in the field of pseudoelasticity.
Understanding the physics of strongly correlated electronic systems has been a central issue in condensed matter physics for decades. In transition metal oxides, strong correlations characteristic of narrow d bands are at the origin of remarkable properties such as the opening of Mott gap, enhanced effective mass, and anomalous vibronic coupling, to mention a few. SrVO3 with V4+ in a 3d1 electronic configuration is the simplest example of a 3D correlated metallic electronic system. Here, the authors' focus on the observation of a (roughly) quadratic temperature dependence of the inverse electron mobility of this seemingly simple system, which is an intriguing property shared by other metallic oxides. The systematic analysis of electronic transport in SrVO3 thin films discloses the limitations of the simplest picture of e-e correlations in a Fermi liquid (FL); instead, it is shown show that the quasi-2D topology of the Fermi surface (FS) and a strong electron-phonon coupling, contributing to dress carriers with a phonon cloud, play a pivotal role on the reported electron spectroscopic, optical, thermodynamic, and transport data. The picture that emerges is not restricted to SrVO3 but can be shared with other 3d and 4d metallic oxides.
The rich functionalities of transition-metal oxides and their interfaces bear an enormous technological potential. Its realization in practical devices requires, however, a significant improvement of yet relatively low electron mobility in oxide materials. Recently, a mobility boost of about 2 orders of magnitude has been demonstrated at the spinel-perovskite γ-Al2O3/SrTiO3 interface compared to the paradigm perovskite-perovskite LaAlO3/SrTiO3 interface. We explore the fundamental physics behind this phenomenon from direct measurements of the momentum-resolved electronic structure of this interface using resonant soft-X-ray angle-resolved photoemission. We find an anomaly in orbital ordering of the mobile electrons in γ-Al2O3/SrTiO3 which depopulates electron states in the top SrTiO3 layer. This rearrangement of the mobile electron system pushes the electron density away from the interface, which reduces its overlap with the interfacial defects and weakens the electron-phonon interaction, both effects contributing to the mobility boost. A crystal-field analysis shows that the band order alters owing to the symmetry breaking between the spinel γ-Al2O3 and perovskite SrTiO3. Band-order engineering, exploiting the fundamental symmetry properties, emerges as another route to boost the performance of oxide devices.
PURPOSE: The aim of this study was to analyze the effects of 10-minute (standard term) versus 20-minute treatment with glutaraldehyde (GA) on mechanical stability and physical strength of human pericardium in the setting of the OZAKI procedure. METHODS: Leftover pericardium (6 patients) was bisected directly after the operation, and one-half was further fixed for 10 additional minutes. Uniaxial tensile tests were performed and ultimate tensile strength (UTS), ultimate tensile strain (uts), and collagen elastic modulus were evaluated. RESULTS: Both treatments resulted in similar values of uniaxial stretching-generated elongations at rupture (10 minutes 25 ± 7 % vs. 20 minutes: 22 ± 5 %; p = 0.05), UTS (5.16 ± 2 MPa vs. 6.54 ± 3 MPa; p = 0.59), and collagen fiber stiffness (elastic modulus: 31.80 ± 15.05 MPa vs. 37.35 ± 15.78 MPa; p = 0.25). CONCLUSION: Prolongation of the fixation time of autologous pericardium has no significant effect on its mechanical stability; thus, extending the intraoperative treatment cannot be recommended.
Glutaral , Pericardium , Tensile Strength , Glutaral/pharmacology , Humans , Pericardium/drug effects , Pericardium/physiology , Tensile Strength/drug effects , Time Factors , Treatment Outcome
A cost-effective, scalable and versatile method of preparing nano-ink without hazardous chemical precursors is a prerequisite for widespread adoption of printed electronics. Precursor-free synthesis by spark discharge is promising for this purpose. The synthesis of platinum nanoparticles (PtNPs) using a spark discharge under Ar, N2, and air has been investigated to prepare highly conductive nano-ink. The size, chemical composition, and mass production rate of PtNPs significantly depended on the carrier gas. Pure metallic PtNPs with sizes of 5.5 ± 1.8 and 7.1 ± 2.4 nm were formed under Ar and N2, respectively. PtNPs with sizes of 18.2 ± 9.0 nm produced using air consisted of amorphous oxide PtO and metallic Pt. The mass production rates of PtNPs were 53 ± 6, 366 ± 59, and 490 ± 36 mg/h using a spark discharge under Ar, N2, and air, respectively. It was found that the energy dissipated in the spark gap is not a significant parameter that determines the mass production rate. Stable Pt nano-ink (25 wt.%) was prepared only on the basis of PtNPs synthesized under air. Narrow (about 30 µm) and conductive Pt lines were formed by the aerosol jet printing with prepared nano-ink. The resistivity of the Pt lines sintered at 750 °C was (1.2 ± 0.1)·10-7 Ω·m, which is about 1.1 times higher than that of bulk Pt.
Alloplastic material is often used for thoracic wall reconstruction following extended resection bringing the risk of infection, especially after chemotherapy and/or radiation. We present the case of a 66-year-old male with lung adenocarcinoma of the right lower lobe. After extended lobectomy, a partial resection of the sixth to eighth ribs followed by chest wall reconstruction with Mersilene mesh and osteosynthesis for sixth and seventh rib was performed. One month postoperatively, he developed pleural empyema. The alloplastic material was removed, extensive surgical debridement was performed and a latissimus dorsi muscle flap was used to cover the chest wall defect and fill out the remnant space supradiaphragmatically. Three years later, the patient has fully recovered with no local pain or relapse of the tumour. This case shows that rigid chest wall reconstruction with a soft autologous muscle flap is a valuable salvage option in case of infection, making alloplastic material highly risky.
Recent experiments reported an unusual nematic behavior of heavily hole-doped pnictides AFe_{2}As_{2}, with alkali A=Rb, Cs. In contrast to the B_{2g} nematic order of the parent AeFe_{2}As_{2} compounds (with alkaline earth Ae=Sr, Ba), characterized by unequal nearest-neighbor Fe-Fe bonds, in the hole-doped systems nematic order is observed in the B_{1g} channel, characterized by unequal next-nearest-neighbor Fe-Fe (diagonal Fe-As-Fe) bonds. In this Letter, using density functional theory, we attribute this behavior to the evolution of the magnetic ground state along the series Ae_{1-x}A_{x}Fe_{2}As_{2}, from single stripes for small x to double stripes for large x. Our simulations using the reduced Stoner theory show that fluctuations of Fe moments are essential for the stability of the double-stripe configuration. We propose that the change in the nature of the magnetic ground state is responsible for the change in the symmetry of the vestigial nematic order that it supports.
OBJECTIVE: To analyze the effects of a surgical protocol for infections, nonhealing wound prophylaxis, and analgesia among patients who underwent posterior spinal fusion at a single tertiary-care neurosurgical center. METHODS: This prospective study was conducted in the neurosurgery department of a tertiary-care neurosurgical center and compared a control group of patients who had posterior spinal fusion within 3 months before implementation of a surgical protocol with a study group of patients enrolled within 1 year after protocol implementation. The protocol included a surgical safety checklist, control of modifiable risks associated with surgical site infection, administration of intrawound vancomycin and local analgesia, and standard closure. Postoperative pain, demand for analgesics, and postoperative surgical site infections were assessed among patients before and after the introduction of the protocol. RESULTS: The control group (n = 35; 30 women; median age, 40 years [interquartile range, 31-54 years]) experienced a higher-than-predicted rate of minor surgical infections and nonhealing wounds (12 patients; 34%). In the study group (n = 113; 74 women; median age, 45 years [interquartile range, 37-54 years]), 11 patients (10%) had minor surgical infections and nonhealing wounds. Introduction of the protocol was associated with a 24% absolute risk reduction for minor surgical site infection and a significant decrease in pain on postoperative days 1 and 2 (P < 0.01 for both). Interpersonal communication improved among specialists involved in patient management. CONCLUSIONS: The protocol was effective in reducing postoperative pain and the rate of surgical site infection among patients with posterior spinal surgeries.
Analgesia/methods , Antibiotic Prophylaxis/methods , Pain Management , Pain, Postoperative/prevention & control , Spinal Fusion/methods , Surgical Wound Infection/prevention & control , Adult , Cohort Studies , Female , Humans , Male , Middle Aged , Pain, Postoperative/psychology , Surgical Wound Infection/psychology , Visual Analog Scale
ABSTRACT Objective: Infectious complications are the most common cause of unsatisfactory results of surgical treatment and prolongation of hospitalization in patients following spinal surgery. The purpose - to assess the microbiological characteristics of SSI in patients after posterior lumbar fusion for degenerative disease, and to determine the relationship between these characteristics and surgical features of SSIs. Methods: A single-center retrospective non-randomized cohort study was performed, 1563 patients aged 37 to 59 years were included in the study. Microbiological characteristics were analyzed, and their interrelations with the surgical features of all cases of SSIs were determined. Results: The incidence of SSIs was 2.67% (41). Monomicrobial SSIs were detected in 46.3% (19) patients, polymicrobial in 36.5% (15) cases, and negative results of inoculation in 17.07% (7) patients. The most frequent pathogens of SSIs in the study group were S. aureus and S. epidermidis - 37.9% (33) and 24.1% (21), respectively. The period of development of symptoms of SSIs in patients after posterior lumbar fusion averaged 25.9±65.3 days. Methicillin-resistant S. aureus and S. epidermidis (MRSA and MRSE) were verified in 24.1% (21) cases. Conclusions: Assessment of microbiological characteristics should be carried out in all diagnosed cases of SSIs in patients after spine surgical interventions, as these are closely linked to the surgical features of the infectious process. Also, the treatment tactics for this group of patients should be determined by a medical team working in conjunction. Level of evidence IV; Descriptive study.
RESUMO Objetivos: As complicações infecciosas são a causa mais comum de resultados insatisfatórios no tratamento cirúrgico e de prolongamento da hospitalização em pacientes após cirurgia da coluna vertebral. O objetivo - avaliar as características microbiológicas do SSI em pacientes após a fusão lombar posterior para sua doença degenerativa e determinar a relação entre essas características e as características cirúrgicas de SSIs. Métodos: Um estudo de coorte retrospectivo não aleatorizado de um centro foi realizado, 1563 pacientes com idade entre 37 e 59 anos foram incluídos no estudo. As características microbiológicas são analisadas e sua interação com as características cirúrgicas de todos os casos de SSIs é determinada. Resultados: A incidência de SSIs foi de 2,67% (41). Os SSI monomicrobianos foram detectados em 46,3% (19) pacientes, polimicrobianos - em 36,5% (15) casos e resultados negativos de inoculação - em 17,07% (7) pacientes. Os agentes patogénicos mais frequentes das SSI no grupo de estudo foram S. aureus e S.epidermidis - 37,9% (33) e 24,1% (21), respectivamente. Conclusões: A avaliação das características microbiológicas deve ser realizada em todos os casos diagnosticados de SSI em pacientes após intervenções cirúrgicas da coluna vertebral em conexão inextricável com as características cirúrgicas do processo infeccioso, e as táticas de tratamento deste grupo de pacientes devem ser determinadas estritamente colegialmente. Nível de evidência IV; Estudo descriptivo.
RESUMEN Objetivo: Las complicaciones infecciosas son la causa más común de resultados insatisfactorios del tratamiento quirúrgico y la prolongación de la hospitalización en pacientes después de la cirugía espinal. El objetivo es evaluar las características microbiológicas de la ISQ en pacientes después de una fusión lumbar posterior por su enfermedad degenerativa, y determinar la relación entre estas características y las características quirúrgicas de las ISQ. Métodos: Se realizó un estudio de cohorte retrospectivo no aleatorizado de un centro, 1563 pacientes de 37 a 59 años de edad fueron incluidos en el estudio. Se analizó las características microbiológicas y se determinó su interrelación con las características quirúrgicas de todos los casos de ISQ. Resultados: La incidencia de ISQ fue del 2,67% (41). Se detectaron ISQ monomicrobianas en 46,3% (19) pacientes, polimicrobianas, en 36,5% (15) casos y resultados negativos de inoculación, en 17,07% (7) pacientes. Los patógenos más frecuentes de las ISQ en el grupo de estudio fueron S. aureus y S. epidermidis: 37,9% (33) y 24,1% (21), respectivamente. El período promedió de desarrollo de síntomas de ISQ en pacientes después de la fusión lumbar posterior fue de 25,9 ± 65,3 días. Conclusiones: La evaluación de las características microbiológicas debe llevarse a cabo en todos los casos diagnosticados de ISQ en pacientes después de intervenciones quirúrgicas espinales en conexión inextricable con las características quirúrgicas del proceso infeccioso. Además de eso, las tácticas de tratamiento de este grupo de pacientes deben determinarse estrictamente de forma colegiada. Nivel de evidencia IV; Estudio descriptivo.
Humans , Surgical Wound Infection , Spine/surgery , Surgical Procedures, Operative , Microbiology
Magnetoelectric coupling and spin polarization at the multiferroic PbTiO3/La2/3Sr1/3MnO3 (PTO/LSMO) interface is studied from first principles in view of the recent experimental observation of the tunneling magnetoresistance sign inversion in Co/PZT/LSMO tunnel junctions (Pantel et al 2012 Nat. Mater. 11 289). Our results confirm the stabilization of the locally antiferromagnetic order in the manganite when the PTO polarization points away from the LSMO side, which changes the interface magnetization by 6.3-6.9 [Formula: see text] per surface unit cell in agreement with previous studies. We contribute by analyzing the charge transfer from the half-metallic LSMO side which induces metallicity and local magnetic moments in the interface PTO layers. This results in either p- or n-doped conductive behavior, depending on the polarization direction. Electronic correlations were determined to qualitatively change the picture for certain configurations, as far as the magnetic phase transition in the manganite and the spin character of the interface states are concerned. Most importantly, depending on the interface termination, the spin polarization of the PTO/LSMO interface is positive for one polarization state of PTO and acquires a 'spin-valve' character upon the ferroelectric switching.
A multiferroic interface between the antiferromagnetic Slater insulator SrTcO3 and ferroelectric BaTiO3 (BTO) is studied from first principles. Although the interfacial magnetoelectric coupling of SrTcO3(001) is relatively small, we found that a two-dimensional electron gas (2DEG) appears for both BaO/TcO2 and TiO2/SrO terminations. The charge character of the carriers, induced in the band gap due to polar BTO, can be switched from electrons to holes by the reversal of the electric polarization in BTO. The 2DEG is robust and stable against the degree of electronic correlations, whereas the paraelectric state of BTO suppresses the 2DEG. The origin of the 2DEG at the BTO/SrTcO3 interface and its key factors are discussed.
