X-RAY studies of ferroelectric lithium niobate crystals doped with rare earth elements

The lattice structural distortions of LiNbO3 crystals doped with samarium with a concentration of 1.0, 1.9, 2.5 mol. % were studied by X-ray diffraction methods. It was found that the samarium atoms and some of the niobium atoms occupied the vacant positions of lithium in the crystal lattice, and some of the niobium atoms were located in the empty octahedron. The octahedra of SmLiO6 was distorted more strongly than octahedra of NbLiO6 when niobium atoms entered the vacant positions of lithium. The smallest changes in the bond lengths in the octahedra of the main motif and in the defect region as well as along the polar axis in the lithium niobate lattice were observed in the sample with a samarium concentration of 2.5 mol. %.

Differential approach to suturing of diastasis of direct abdominal muscles

Aim of study. To reduce the rate of recurrence after diastasis suturing. Material and methods. The study included 86 female patients. Abdominal volumes and diastasis levels were assessed. The presence of diastasis of rectus abdominis was confirmed (physically and by additional instrumental research methods: ultrasound of the anterior abdominal wall and electromyography of the direct abdominal muscles). All patients were divided into 4 groups based on the level of diastasis. In group 1, aponeurosis was normal, diastasis of the direct abdominal muscles was not observed. In group 2, diastasis of the direct abdominal muscles was observed in the epigastric region (from the xiphoid process to the navel, diastasis suturing was performed in the defect region). In group 3, diastasis of the direct abdominal muscles was observed in the hypogastrium (from the umbilicus to the womb, suturing of the diastasis was performed in the defect region). In group 4, diastasis was observed in straight abdominal muscles along the entire white abdominal line (from the umbilicus to the womb, diastasis suturing was performed in the defect area). Results. The surgery utilised a differential approach to diastasis suturing depending on the level of diastasis. In the long term, there was no relapse in the relapse groups. Improvement in the functional state of the anterior abdominal wall was also noted by the patients after surgery. A year after the intervention, patients underwent a survey and indicated a significantly smaller chronic pain syndrome in the umbilical ring and white line as well as significant improvement of cosmetic satisfaction. Conclusion. Application of differential approach and additional instrumental examination in the preoperative period (ultrasound examination of the anterior abdominal wall and electromyography of direct abdominal muscles) reduces the frequency of postoperative relapse of diastasis

A novel extraction method for weld defect segmentation seeds using ANDM and clustering

To improve the accuracy and reliability in extracting defect segmentation seeds from a weld radiographic testing (RT) image, a novel extraction method (NESS) using clustering and a novel defect detection method (ANDM) that was presented in a previous paper by one of the authors is proposed in this paper. In the proposed NESS, firstly each column of the weld RT image is accurately analysed by ANDM to judge whether or not it really passes through weld defect regions. Most importantly, one or more defect seeds can be acquired if it passes through a defect region. Secondly, all the defect seeds (a defect seed group) of the RT image are extracted by analysing the entire image. Finally, a sorting-based clustering method is proposed to quickly and accurately search for defect segmentation seeds among all the defect seeds, which can solve the problems concerning the difficulty in determining defect segmentation seeds and the heavy calculational burden of defect segmentation. In order to evaluate the performance of the proposed NESS, some clustering and segmentation experiments have been performed. The experimental results reveal that the proposed NESS achieves high accuracy and reliability in extracting defect segmentation seeds from RT images and is helpful in defect segmentation.

Blowhole Detection Based on Bidirectional Enhancement and Omnidirectional Analysis for X-Ray Inspection of Castings

Small blurred blowholes are difficult to detect, especially those in castings having a complex structure. In this paper, we propose a blowhole detection method based on bidirectional enhancement and omnidirectional analysis for X-ray inspection of castings. After obtaining the X-ray images of a casting from the X-ray inspection equipment, there are two main processes to detect the blowholes. First, in the extraction process for the potential defect region, we propose a method based on bidirectional enhancement that highlights the blurred defects and models the nondefective structure. Second, in the precise defect identification process, we propose a method to distinguish real defects by 3D model fitting-based omnidirectional analysis. The experimental results indicate that the proposed method has a higher performance in blowhole detection than comparable methods.

An Analytical Description of the Magnetic Conductance Across an Isolated Defect Region in a 1D-Ferromagnetic Lead

We illustrate in this contribution the determination of the magnetic conductance across a nanocontact region defined by an isolated defect region joined between two mono-atomic leads ferromagnetically ordered. The system is described by the Heisenberg interaction. Additionally, to deal with the lack of symmetry across the contact region defined by the isolated defect, we involve the phase field matching approach. Furthermore, to compute the quantum conductance, we define the quantum scattering of the transmission and reflection probabilities within the framework of Landauer–Büttiker formalism. Based on these approaches, we present an analytical expression of the magnetic conductance. The obtained analytical results based on our adopted procedures confirm the known results adopted for perfect infinite leads (no defect). Our model calculations can be applied numerically when we deal with doping across the defect region. The adopted model could be also used numerically to deal with the impurity configurations that one might encounter in real systems.

Моделирование образования каскада смещений и переходных ионизационных процессов в кремниевых полупроводниковых структурах при нейтронном воздействии

The formation of a disordered defect region in bulk silicon is simulated using the molecular-dynamics method for various energies of a primary recoil atom. Variations in the volume and number of radiation-induced defects in a cluster during its formation are calculated. The generation rates of nonequilibrium carriers and amplitude-temporal dependences of pulses of ionization currents in test Schottky diodes with hyperhigh frequencies are found theoretically.

Restoration of limited defects of the cartilage with the use of cell-engineered constructs

Aim: to develop a three-dimensional composite cell-engineered constructs (CEC) for restoration of limited defects of the cartilage in experiment.Materials and methods. To create a cell-engineered constructs (CEC), were used collagenic carriers: «Chondro Gide» impermeable bilayer membrane and «Osteoplast» permeable matrix. A comparative study of their cytotoxic and adhesion properties was made in vitro. Chondroplastic potential of prepared CECs based on collagenous matrices with allogeneic mesenchymal stem cells (MSC) of the rabbit bone marrow grown on their surface was assessed in vivo. A cylindrical defect of the cartilage of the medial femoral condyle 3.3 mm in diameter at a depth of 1.5 mm was formed on both rabbit feet. Laboratory animals were divided into 3 groups: control group; Experiment 1 group with Chondro Gide used as the MSC carrier within CEC; Experiment 2 group using Osteoplast matrix. Upon experiment completion, a morphometric and histomorphologic research of tissue specimens was made. For statistical evaluation of the results a defect region recovery factor (RF) was offered and used. Results. After a 6-month observation period the control group showed partial recovery of the defect region with the recovery factor (RF) of 0.62 ± 0.06. The RF in Experiment 1 group equalled to 0.79 ± 0.07, Experiment 2 group revealed RF at the level of 0.88 ± 0.02. Statistical analysis of the research results shows that the use of CEC used in Experiment 2 group reduces a relative risk of therapeutic failures by 92.9%, and absolute risk – by 43.3% as compared to Experiment 1 group. Histomorphologic research data are indicative of a hyaline cartilage formation in the central defect zone, which is partially close to the intact cartilage to the maximum with zonality marked.Conclusion. Results of the research of the developed three-dimension cell-engineered constructs consisting of mesenchymal stem cells of the bone marrow grown on the Osteoplast permeable collagenic matrix show the formation of a cartilaginous hyaline tissue with a high level of structural organization in the area of its implantation. The thickness of a newly formed cartilage is insignifi cantly less than that of the preceding cartilaginous tissue, thus facilitating a dynamic distribution of the axial load on the articular surface, and as a whole this holds out hope for good long-term results. Therefore, based on the data obtained, we consider it reasonable to perform next investigation phases of the offered cell-engineered constructs for chondroplasty of limited cartilage defects.

An Innovative Technique for Hollowing a Prosthesis with Excessive Vertical Height Using Polyvinyl Siloxane Putty

Rehabilitation of hemimaxillectomy patients is a very challenging process. The augmented weight of the prosthesis when closing large defects is often a concern to its retention and lightweight obturators are thus warranted in such clinical situations. Most of the techniques in literature to hollow a prosthesis were designed to make only the defect region of obturator hollow and has limited application when it comes to prosthesis with excessive vertical height. This technique described in this article can be used to hollow vertical height of any prosthesis and successfully replace conventional techniques when they are not feasible.