Evaluation of microstructure and conductivity of two-phase materials by the scanning spreading resistance microscopy (the case of shungite).

The determination of the content of the conducting phase and the assessment of conductivity by microscopic images are interesting for rapid and non-destructive analysis of the electrophysical properties of two-phase (conductor/dielectric) samples during the atomic force microscopy. In this paper we summarized results of the analysis of the conductivity maps of the shungite surface by the method of discretization by applying a square grid with subsequent binary digital processing. Microstructure and conductivity were evaluated by measuring the average length of continuous conductive circuits isolated on the grid. A model was considered that established a unique correspondence (up to normalizing coefficients) between the length of the conductive circuits on the conductivity maps and the integral conductivity of the sample as a whole. An analytical equation was obtained that described such dependence with an accuracy of units of percent. We proposed a method for measuring the integral conductivity of a shungite samples based on an analysis of its binary conductivity map obtained by spreading resistance microscopy. This method can be used to determine the conductivity by surface conductivity mapping for shungite-like two-phase conductor/dielectric systems, and in general, for any two-phase substances where the phases differ in AFM-determined properties.

[Experience in surgical treatment of injuries of the major vessels]. / Opyt khirurgicheskogo lecheniia povrezhdenii magistral'nykh sosudov.

Eighty-one patients were treated for injuries to the main vessels. They underwent operations at the Novgorod Regional Hospital and in surgical departments of the Novgorod Region. The injuries of the vessels were open in 90.1% and closed in 9.9% of patients. Among 125 reconstructive operations good results with restoration of arterial and venous blood flow and maintained function of the limb were produced in 67.9% and satisfactory results in 9.9% of patients. Amputation of the limb was carried out in 13 patients (16.0%). Mortality was 7.4% (six patients). The authors emphasize that early admission of patients to the hospital and the therapeutic tactics in a vascular trauma guarantee preservation of the injured limb, restoration of its function, and save the patient's life.

[Surgical treatment of recurrent aortic-iliac-femoral occlusions]. / Khirurgicheskaia taktika pri reokkliuziiakh v aortopodvzdoshno-bedrennom segmente.

At the department of vascular surgery of the Novgorod Regional Hospital 455 reconstructive operations for atherosclerotic occlusions in the aorto-ileo-femoral segment were performed in 1984-1991. Thrombotic reocclusion occurred in 58 patients (12.7%) for which a second operation had to be conducted, early thromboses of the reconstructed segment were encountered in 16 patients (3.5%) and late thromboses in 42 (9.2%). The work analyses the causes of early and late reocclusions, substantiates the surgical tactics, and discusses the technical characteristics of the operation. Thrombectomy with reconstruction of the distal anastomosis and the draining paths was the main method of treatment. It was conducted in 12 patients with early and in 21 patients with late reocclusions. The results of surgical treatment are shown. It is concluded that repeated reconstructive operations are a sufficiently effective measure for preserving the function of the earlier operated on limb; they made it possible to produce positive immediate results in 81.0% and late-term results in 64.3% of patients.

[The surgical treatment of superficial thrombophlebitis of the lower extremities]. / Khirurgicheskoe lechenie poverkhnostnogo tromboflebita nizhnikh konechnostei.

The work gives an analysis of results of the surgical treatment of superficial thrombophlebitis of lower extremities. Operations were performed on 70 patients. Subcutaneous thrombophlebitis was considered as acute surgical disease. An active surgical tactics is proposed. The authors show that operative treatment is not dangerous for the patients, reduces the time of the hospital and ambulatory treatment of the patients.

[Repeated operations after reconstructive interventions on the aortofemoral segment]. / Povtornye operatsii posle rekonstruktivnykh vmeshatel'stv v aortobedrennom segmente.

At the department of vascular surgery of the Novgorod regional hospital 455 reconstructive operations for atherosclerotic occlusions in the aorto-femoral segment were performed at the period from 1984 to 1991. Specific complications requiring reconstructive reoperations took place in 92 patients (20.2%), 21 patients (4.6%) having earlier specific complications and 71 patients (15.6%)--late ones. Causes of the appearance of the specific complications are analyzed, the methods of treatment of such patients are recommended. Lethality after reoperations for late complications made up 9.8%, amputation of the extremity was performed in 14.1% of the patients. The positive result of the reoperations with a regress of ischemia and the preserved function of the extremity was noted in 76.1% of the patients.

[Atherosclerotic aneurysm of the iliac arteries]. / Ateroskleroticheskkaia anevrizma podvzdoshnykh arterii.

Operations were performed on 5 patients with isolated atherosclerotic aneurysms of the iliac arteries, who accounted for 10.9% of patients with aneurysms of vessels treated at the Vascular Department of the Novgorod Regional Hospital from 1983 to 1990. In 4 patients the aneurysm of the iliac artery was an operative finding, in one patient it was found only on postmortem examination. The diagnostic errors and causes of a fatal outcome in 2 patients are discussed. The authors claim resection of the aneurysm with reconstruction of the aorto-ilio-femoral segment to be the operation of choice in aneurysm of the iliac artery.

[Surgical treatment of occlusive diseases of the brachiocephalic arteries]. / Khirurgicheskoe lechenie okkliuziruiushchikh zabolevanii brakhitsefal'nykh arterii.

Experience of the department of vascular surgery of the Novgorod Regional Hospital from 1985 is analysed. The department has the standard sets of instruments, equipment, and roentgenodiagnostic apparatus which allow catheter, selective, and puncture angiography to be carried out. Thirty-six operations were performed on 28 patients. All were conducted under endotracheal anesthesia with medicamentous protection of the brain. One patients died from reflex cardiac arrest. No complications occurred in the other operations and their results were positive. It is concluded that reconstructive operations on the brachiocephalic trunks can be successfully performed in angiosurgical departments of regional and city hospitals with a personnel skilled in diagnosis and a trained angiosurgeon and anesthesiologist on the staff.

[Artificial normovolemic hemodilution with preoperative blood preservation in reconstructive operations in the aorto-iliac region]. / Iskusstvennaia normovolemicheskaia diliutsiia s predoperatsionnym rezervirovaniem chasti krovi pri rekonstruktivnykh operatsiiakh v aortopodvzdoshnoi zone.

The artificial normovolemic hemodilution allows to improve results of planned aortobifemoral shunts in patients with the Leriche syndrome. The method was used in 45 of 138 operations of this kind. The level of postoperative complications was reduced from 33.3% to 22.2%, that of anemia--from 25.8 to 13.3%, postoperative lethality became lower (from 11.8 to 4.4%).

[Status of cerebral ventricles and meninges in subarachnoid hemorrhage (clinico-pathomorphological studies)]. / Sostoianie zheludochkov i obolochek golovnogo mozga pri subarakhnoida'lnykh krovoizliianiiakh (kliniko-patomorfologi- cheskoe issledovanie).

Long-term investigation of 64 patients with subarachnoidal hemorrhages (SH), 24 of which had subsequently died, and 2 series of experiments of animals with a single or repeated intracysternal infusion of various doses of autologous blood, yielded the description of the response of the meninges and ventricles at different terms after SH. The brain ventricles were measured by axial computer tomography and echoencephalography. A index of CSF resorption resistance and CSF pressure were determined. The cerebral meninges from experimental animals and autopsied human ones underwent the histological examination. The authors discuss the mechanisms of development of liquor dynamic disorders at different terms after SH.

[Radioisotope encephaloscintigraphy in the diagnosis of acoustic nerve neurinomas]. / Radioizotopnaia éntsefalostsintigrafiia v diagnostike nevrinom slukhovogo nerva

The results of the employment of radiopharmaceuticals in a group of patients with acoustic neurinomas for diagnostic purposes are described. High diagnostic efficacy of the method of radioisotope encephaloscintigraphy is emphasized, the method permitting to obtain extended diagnostic information. An important advantage of the method consists in its safety and absence of contraindicaions.

[Experience with the use of intravascular interventions using a balloon catheter for several types of cerebral pathology]. / Opyt primeneniia intravaskuliarnykh vmeshatel'stv s pomoshch'iu ballon-katetera pri nekotorykh vidakh tserebral'noi patologii

Detachable balloon catheters were used during 38 intravascular procedures in 25 patients with vascular lesions and tumours of the brain. Permanent balloon occlusion of the cavernous part of the internal corotid artery or a reconstruction of this portion of the carotid artery, with its function preserved, was performed in patients with carotid-cavernous fistulas. In arterio-venous aneurysms one or two afferent vessels were occluded, while in cases of arterial aneurysm the latter was blocked itself. In cerebral neoplasms balloon catheters were used to precise the blood supply sources of the tumor, to occlude the vessels supplying meningiomas, and to perform intravital staining of the glial tumors. Positive results were obtained in 24 of the 25 patients. One patient died of middle cerebral artery thrombosis. The method of catheterization and occlusion of cerebral vessels with the aid of balloon catheters proved effective in the examination and treatment of patients with some vascular lesions and tumors of the brain.