The paper presents two methods for identifying microstructural heterogeneities on the surface of OFAM-K and OPMN-P nanofiltration membranes. Optical microscopy in combination with the AutoCad 2016 ...computer-aided design system and standard Microsoft Excel 2010 tools allows one to investigate microstructural heterogeneities of initial samples of OPMN-P and OFAM-K nanofiltration membranes. A method that enables the automated calculation of the average diameter of the fouling of semi-permeable membranes and the fouling coefficient of porous bodies is also developed. Using the capabilities of the Matlab 2017 software package, the application of modern tools to accomplish the set goal of the work is shown. Practical implementation of the method is exemplified by the nanofiltration process with semi-permeable polymer membranes of OFAM-K and OPMN-P types. The automated method combining optical microscopy studies, Otsu image processing, and software implementation in Matlab 2017 and optical microscopy in combination with the AutoCad 2016 computer-aided design system and standard Microsoft Excel 2010 tools, which more accurately reveals the structural heterogeneities of OFAM-K and OPMN-P nanofiltration membranes, are compared.
Giant cerebral aneurysms are diagnosed more often in children than in adults. Treatment of giant aneurysms is carried out both by endovascular and microsurgical methods. Literature information on ...combination of microsurgical and endovascular operations of cerebral aneurysms at children is little. A clinical case of the combined treatment of a giant bicameral fusiform partially thrombosed aneurysm of the right vertebral artery at a 12-year-old patient and a literature review on this topic are presented. The patient underwent several complex neurosurgical interventions during two operations: 1) microsurgery including revascularization of the right posterior lower cerebellar artery, thrombectomy and trapping of the larger chamber of fusiform aneurysm of the right vertebral artery, and 2) endovascular, which consists in the installation of redirecting stent from the left vertebral artery to main artery. The uniqueness of the case which we presented lies in the fact that the tactics of stage combined treatment for a complex aneurysm at child was originally planned and successfully implemented. The treatment allowed to ensure a complete shutdown of aneurysm and to exclude postoperative cerebral complications.
Significant photocurrent/photoconductivity amplification is observed at low reverse biases in a type-II
n
-GaSb/InAs/
p
-GaSb heterostructure with a single quantum well (QW), grown by metal-organic ...vapor phase epitaxy. A sharp increase in the photocurrent by more than two orders of magnitude occurs under exposure of the heterostructure to monochromatic light with a wavelength of 1.2–1.6 μm (at 77 K) and the application of a reverse bias in the range 5–200 mV. The optical gain depends on the applied voltage and increases to 2.5 × 10
2
at a reverse bias of 800 mV. Theoretical analysis demonstrated that the main role in the phenomenon is played by the screening of the external electric field by electrons accumulated in the deep InAs QW and by the mechanism of the tunneling transport of carriers with a small effective mass. It is shown that the effect under study is common to both isotype and anisotype type-II heterojunctions, including structures with QWs and superlattices.
Treatment of cerebral aneurysms in the acute stage of subarachnoid hemorrhage (SRH) especially on the background of cerebral vasospasm continues to be a difficult task.
Assessment of dynamics of the ...surgical treatment results of patients with cerebral aneurysms in acute period of SRH.
A comparative analysis of the results of patients' surgical treatment in NMRCN Burdenko about aneurysm in 1-21 days after hemorrhage was made. The following periods were selected: 2006-2014 (343 patients) and 2015-2018 (356 patients). Most patients had microsurgical operations in both periods. The tactics of choosing the surgery time was the main difference between the periods: particularly in 2015-2018 period the surgery was not postponed at patients with severe.
Analysing the post surgical mortality, it was found that since 2006 there is a consistent trend towards a decrease in the number of patients who died after surgery. When calculating the average post surgical mortality for the studied periods this trend is confirmed - number of lethal cases in 2015-2018 reliably decreased when comparing with 2006-2014 - from 6.8 till 3.2%; p=0.03. At the same time, the number of patients with outcome of vegetative status (from 0.3 till 5%).
The tactics of surgical treatment of patients with cerebral aneurysms in the acute period of SRH regardless of severity of patient's condition and time of hemorrhage did not lead to worse treatment. In contrast, post surgical mortality rates show a consistent decline. We associate this fact with a number of changes that have occurred in the management and treatment of patients. In particular, we have high hopes for developing new approaches to the treatment of vasospasm, which remains the leading cause of lethal cases. More definite conclusions will be made at the end of the treatment analysis of the respective patient groups.
The study purpose was to analyze the efficacy of intra-arterial administration of verapamil (IAV) in the treatment of angiospasm in SAH patients and to determine optimal parameters of the procedure. ...A number of studies demonstrated the efficacy of intra-arterial administration of vasodilators, in particular verapamil, in the treatment of angiospasm after aneurysmal SAH, which served the basis for inclusion of this method in the recommended protocol for treatment of SAH patients 1-7.
We analyzed the efficacy of IAV in 35 patients in the acute period of SAH, with 77.2% of the patients having a Hunt-Hess score of III-V. The inclusion criteria were as follows: IAV within two weeks after SAH; excluded aneurysm; verapamil dose per administration of at least 15 mg; follow-up for at least three months. Efficacy endpoints were as follows: changes in spasm according to angiography and transcranial dopplerography (TCDG); development of ischemic lesions; clinical outcome according to the modified Rankin scale.
A total of 76 IAV procedures were performed. The verapamil dose per procedure was 36.7±9.7 mg, on average; the number of procedures varied from 1 to 5. One arterial territory was treated in 12 cases, two arterial territories were treated in 48 cases, and three arterial territories were treated in 15 cases. Typical adverse reactions included decreased blood pressure, a reduced heart rate, and elevated ICP. In all cases, TCDG revealed signs of reduced angiospasm - a 20-40% decrease in the LBFV in the M1 MCA. Four (11.4%) patients died; of these, only one died due to angiospasm progression. On examination at 3 months or more after discharge, favorable outcomes were observed in 74.3% of cases.
IAV is associated with a low risk of significant complications. IAV should be performed under control of systemic hemodynamics and ICP. The indications for IAV include signs of moderate worsening or severe angiospasm according to TCDG and/or angiography. The IAV procedure may be performed every day. Further clarification of the IAV procedure and evaluation of clinical outcomes under prospective study conditions are required.
To describe own experience of treating patients with extramedullary tumors at the level of craniovertebral junction using minimally invasive surgical approaches.
The study included 29 patients who ...underwent minimally invasive microsurgical resection of extramedullary tumors at the level of craniovertebral junction. We analyzed the main clinical and surgical parameters.
Gross total resection was achieved in most patients with high degree of safety. Two patients required redo surgery due to CSF leakage and soft tissue cyst. Mean length of hospital-stay was 7 days. VAS score of pain syndrome at discharge was 2 points and 0 points after 3 months. No significant differences in neurophysiological monitoring indicators were observed (
=0.76).
Minimally invasive posterior approaches to extramedullary tumors at the level of craniovertebral junction can significantly reduce surgical trauma with equal extent of resection.
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