Field Modeling of the Influence of Defects Caused by Bending of Conductive Textronic Layers on Their Electrical Conductivity.

One of the critical parameters of thin-film electrically conductive structures in wearable electronics systems is their conductivity. In the process of using such structures, especially during bending, defects and microcracks appear that affect their electrical parameters. Understanding these phenomena in the case of thin layers made on flexible substrates, including textile ones, which are incorporated in sensors that monitor vital functions, is a key aspect when applying such solutions. Cracks and defects in such structures appearing during their use may be critical for the correct operation of such systems. In this study, the influence of defects resulting from the repeated bending of the conductive layer on its conductivity is analyzed. The anisotropic and partly stochastic characteristics of the defects are also taken into account. The defects are modeled in the form of broken lines, whose segments are generated in successive iterative steps, thus simulating the gradual wear of the layer material. The lengths and inclinations of these sections are determined randomly, which makes it possible to consider the irregularity of real defects of this type. It was found that near the percolation threshold, defects with a more irregular shape have a dominant effect on the reduction of conductivity due to the greater probability of their connection. The simulation results were compared with the experimental data. It was found that the dependence of the conductivity of the conductive layer on the number of bends is logarithmic. This allowed for the derivation of a formula linking the iteration number of the simulation procedure with the number of bends. Improving the strength of such layers is a technological challenge for researchers.

QCL Active Area Modeling with a View to Being Applied to Chemical Substance Detection Systems.

Numerical research into the QCL tunability aspects in respect to being applied in chemical substance detection systems is covered in this paper. The QCL tuning opportunities by varying power supply conditions and geometric dimensions of the active area have been considered. Two models for superlattice finite (FSML) and infinite (RSM) size were assumed for simulations. The results obtained have been correlated with the absorption map for selected chemical substances in order to identify the potential detection possibilities.

[The treatment of dissected thoraco-abdominal aorta aneurysm with the use hybrid procedure]. / Zaopatrzenie tetniaka aorty piersiowo-brzusznej przy uzyciu procedur hybrydowych.

AIM OF STUDY: We analyzed the case of a patient treated in Vascular Surgery Department with the use of the hybrid procedure with a good results. MATERIALS AND METHODS: Acute cases of dissected aortic aneurysm are commonly known as an immediate danger of human live and determinate a big challenge for physicians. The collaboration of classic and endovascular methods (hybrid procedures) gives much more chances to improve patient's survival and resumption to normal life activity. Endovascular procedures are limiting the operation shock, improving recovery time. That means rising the chances of survival so advanced surgical procedure. CONCLUSION: Hybrid procedures are a modern technic that gives good results.

Optimisation of QCL Structures Modelling by Polynomial Approximation.

Modelling of quantum cascade laser (QCL) structures, despite a regular progress in the field, still remains a complex task in both analytical and numerical aspects. Computer simulations of such nanodevices require large operating memories and effective algorithms to be applied. Promisingly, by applying semi-analytical polynomial approximation method to computing potential, wave functions and electron charge distribution, accurate results and quick convergence of the self-consistent solution for the Schrödinger and Poisson equations are reachable. Additionally, such an approach makes the respective numerical models competitively effective. For contemporary QCL structures, with quantum wells quite typically forming complex systems, a special approach to determining self energies and coefficients of approximating polynomials is required. Under this paper we have analysed whether the polynomial approximation method can be successfully applied to solving the Schrödinger equation in QCL. A new algorithm for determining self energies has been proposed and a new method has been optimised for the researched structures. The developed solutions have been implemented as a new module for the finite model of the superlattice (FMSL) and tested on the QCL emitting light in the mid-infrared range.

[The use of vascular prothesis Gore Viabahn in the managment of the lower limbs ischemia]. / Zastosowanie protezy Gore Viabahn w leczeniu przewleklego niedokrwienia konczyn dolnych.

The chronic lower limbs ischaemia is caused mainly by arteriosclerosis. After insufficient conservative treatment only the surgical intervention can salvage the limb. The revascularisation surgery can be performed by open surgery with implantation of the prosthetic bypass or by endovascular angioplasty with stent. This second method seems to be the best alternative for the patients with several concomitant systemic diseases. Nevertheless it is limited by presence of the long-distance arteriosclerotic lesions. The resolve of that problem is use of new generation of long endovascular covered stents. They can be succesfuly used in aorto-femoral and femoro-popliteal segment. Their efficiacy is simmilar to traditional prosthetic grafts.

[The use of the synthetic silver coated prosthesis and penduculated omentum flap in the treatment of prostheses infection]. / Zastosowanie syntetycznej protezy impregnowanej solami srebra i plata sieci wiekszej w leczeniu zakazen protez naczyniowych.

There is a methods of surgical treatment of secondary enteroaortal fistula after infection of vascular prostheses with the use silver prosthesis and great omentum. Secondary enteroaortal fistula is the most serious complication followed infection of vascular prosthesis, with high risk of death rate regardless of different operative methods. Patients is operated and the dracon prosthesis was exchanged to arterial homograft, which is more resistant to infections or subclavio-femoral bypasses. Removing of intestinal fistula included resection of duodenum and gastroenterotomy or duodenorrhaphy. The modification of duodenal fistula provision relies on duodenorraphy and protection of that area and prosthesis with pediculated flap of gastrocolic omentum conducted retrocolicaly in retroperitoneum space. The retrocolical and retroperitoneal omentoplasty seems to be a practical modification of aorto-duodenal fistula treatment with useful protection of duodenal plastic.

[The comparison of the healing of the classic vascular prostheses and stentgrafts in the abdominal aneursyms]. / Porównanie wgajania syntetycznych protez naczyniowych klasycznych i wewnatrznaczyniowych w tetniakach aorty brzusznej.

THE PURPOSE: Every foreign body injected into an organism causes an inflammatory condition. Among other things leukocytes take part in it. The healing of a vascular prosthesis means gradual subsiding of an inflammatory condition. The process can be monitored with the series of scintigraphy following decrease of an area of concentrating of Technetium-labeled leukocytes. The purpose of work was an appraisal of the healing of both types of prostheses in cases of patients operated because of aneurism of abdominal aorta. MATERIAL AND METHODS: In three years 64 patients have been examined. They were divided into two equal groups: I-patients after (stent-graft) being implanted because of abdominal aneurysm, II-patients after aortobifemoral prosthesis being implanted of the same reason. The scintigraphy was done in 3-4 day, in 3-, 6- and 12 after a surgery. A surface of concentrating of leucocytes was counted in a computer programme which allows manual marking of a contour. The results were put through a statistical processing. RESULTS: During a period after surgery an intensified inflammatory condition has been stated in a group of patients operated in classic way. In both groups a decreasing of an inflammatory condition has been observed. After 12 months an area of concentrating of leucocytes took up to 10 percent of initial values. CONCLUSIONS: The decreasing of an area of concentrating of leucocytes was observed independently of a type of vascular prosthesis. The higher reaction was where the classic prostheses were used. The scintigraphy shows only a cellular part of an inflammatory answer and it cannot be an independent way of a monitoring of the healing of the prostheses.

[The use of silver/collagen coated vascular prostheses in the treatment of critical limbs ischemia]. / Stosowanie protez naczyniowych impregnowanych solami srebra i uszczelnianych kolagenem w krytycznym niedokrwieniu konczyn dolnych.

Critical lower limb ischemia is a term used to define those patients with chronic ischemic pain at rest, ulcerations or limb necrosis caused by confirmed atherosclerotic lesions of the arteries. In this paper to evaluate of the clinical usefulness of silver coated prostheses in critical lower limb ischemia was presented. The use of the vascular artificial prostheses (dacron, dacron with velour, dacron albumin coated, polytetrafluoroethylene, dacron gentamicin/ryfampicin coated) in the critical ischemia limbs threatened is her contagion. In cases of potentially threatened a contagion is indicated the use of vascular prostheses about enlarged resistance on the contagion, e.g. the silver/collagen coated prosthesis. A foundation of the use of such prostheses are antibacterial proprieties of polyester fibers salts of the silver. An aim of many works is estimation of healing of the silver prostheses of grafted in lower limb at ill with the critical ischemia where infecting of the synthetic material is extremely probable. The healing of the silver prosthesis rated is most often at the use of the scintigraphy with Technetium 99. One attends that such research will make possible the estimation of the usefulness of the vascular silver prostheses in reconstructive operations in the vascular surgery, particularly in cases threatened with the infection of used synthetic material.

[The surgery and endovascular surgery of thoracoabdominal aortic aneurysms with the use of vascular prostheses]. / Leczenie operacyjne i wewnqtrznaczyniowe tetniaków aorty piersiowo-brzusznej z wykorzystaniem protez naczyniowych.

The authors present etiology, diagnosis and operative treatment of thoracoabdominal aneurysms based on their own experiences, especially in performing proximal anastomosis between vascular graft and aorta. The protheses are made of polytertafluoroethylene or dacron. They are impregnated with colagen or soaked with argentum or antibiotics. Spinal cord and visceral organ protection is described. The authors present also endovascular treatment of aorta. Internal chasis of vascular protheses (stentgrafts) is made of biologically neutral metal (like stainless stell, nitinol, other alloys). Its diameter is simmilar to abdominal or thoracic aorta dimension. The chasis is covered by material used also to produce classic vascular protheses (polytetrafluoroethylene, dacron). Thoracoabdominal aneurysms occur rarely, but they are the most difficult problem in vascular surgery. According to literature occurrence of aneurysms in this section value from 4% to 10%. Atherosclerotic process is a exciting cause of this type of aneurysms. According to modified Crawfords classification there are five basic types of thoracoabdominal aneurysms. For pioneer of thoracoabdominal aneurysms surgical treatment one should to recognize S. Etheredge, who in 1954 as a first performed human, aortal homograft implantation with using temporary by-pass. In 1973 E. S. Crawford proposed a new way of management depended on in situ anastomosis between arterial trunks with prosthesis, without use of temporary bypass. In Anglo-Saxon literature this technique gained descriptive qualification "clamp and sew". Using this method, thoracoabdominal aneurysms surgery stood himself decidedly shorter and safer for patients.

[The treatment of abdominal aortic aneurysms by use of endovascular prosthesis and classic vascular prosthesis]. / Leczenie tetniaków aorty brzusznej z wykorzystaniem protez wewnatrznaczyniowych i klasycznych.

The abdominal aortic aneurysm is a dilatation of infrarenal part of aorta. Its ethiology is still unknown. An infection and congenital disorders of conjunctive tissue are regarded as the main risc factors. Other factors could be a perimural thrombus and elastin and colagen degradation. It's not proved that atheromatosis is a risc factor. The disease concerns mainly the old males. Not treated aneurysm grows until rupture. The aneurysms are usually asympthomatic. Majority of them are found incidentally. Ultrasonography and computed tomography are used to extended diagnosis. The open surgery or endovascular surgery are only possible ways of treatment. The aneurysm with diameter over 55 milimeters, sympthomatic or rupted is an indication for surgery. The aim of the open surgery is implantation of the vascular prosthesis into retroperitoneal space. Endovascular method consist in placement of stent-graft in the lumen of aneurysm through small incision in a peripherial vessel. Stent-graft consists of metal chassis covered by classic vascular prosthesis. This method still requires the long-term assessment.

[The use of silver/collagen coated vascular prostheses in infected environment]. / Zastosowanie dakronowej protezy naczyniowej, impregnowanej solami srebra i uszczelnianej kolagenem w zakaionym srodowisku.

The purpose of this study is to evaluate of the use of and silver-coated medical prosthesis in cases of the massive vascular graft infection. In this paper the use of silver-coated medical prosthesis (29 patients) of massive dacron graft infection in Departament of Vascular, General and Transplantation Surgery In Wroclaw University of Medicine In the years 1999-2004 is presented. For lack of tissue material and because of the exclusion of extraanatomic bypass application, in situ replacement was attempted using silver-coated dacron vascular prosthesis more resistant to infection. Before and after the surgery in all patients imaging studies were performed. Duplex-Doppler Ultrasound demonstrated perigraft fluid collections and the scintigraphy with use of Technetium-labeled leukocytes revealed vast migration to the infected prosthesis. The remission of the symptoms of infection was obtained. In the postoperative follow up no perigraft fluid collections were observed. In the most cases positive clinical effect was obtained, the scintigraphy of implanted graft revealed its infection. Because the scintigraphy disclosed Technetium-labeled leukocytes vast migration to the implanted graft, the application of silver coated medical prosthesis should be very cautious and limited to the critical states.

[Presence of Chlamydia pneumoniae in the carotid artery]. / Wystepowanie Chlamydia pneumoniae w tetnicach szyjnych.

UNLABELLED: There is growing experimental evidence that Chlamydia pneumoniae is a risk factor and contribute to the development of atherosclerosis of carotid artery. This process might cause stenosis of carotid artery and TIA or stroke. AIM: Aim of this study was to evaluate the frequency of Ch. pneumoniae infection in carotid artery stenosis patients and in control group-healthy artery from multiorgan donors. MATERIAL AND METHODS: From each of 84 patients undergoing carotid endarterectomy the samples were analyzed by nested PCR for Ch. pneumoniae DNA. Furthermore we determined DNA Ch. pneumoniae in carotid artery from 20 multiorgan donors. RESULTS: In control group-healthy artery the PCR for Ch. pneumoniae was negative in all samples. Ch. pneumoniae was detected in 57 patients (67.85%) with symptomatic carotid artery stenosis, however in 27 patients (32.15%) the PCR test was negative. CONCLUSIONS: We did not observe infection of Ch. pneumoniae in healthy carotid artery-control group. We noted great frequency of infection in patients with stenosis of carotid artery. Patients with stenosis of carotid artery can be candidates to antibiotic therapy, which can slow down the progression of artery stenosis.

[Incidence of factor VII and C3 in vascular anastomosis]. / Wystepowanie czynnika VII krzepniecia krwi oraz czynnika C3 ukladu dopelniacza w zespoleniach naczyniowych.

In order to study pathogenesis of vascular prosthesis healing process the following experiment was designed. 16 dogs underwent implantation of unilateral straight aorto-femoral teflon (PTFE, polytetrafluoroethylene) by-pass. After 6 months all dogs were killed, dissected and vascular prostheses with margin of adjacent aorta and femoral artery were collected for further study. Areas of proximal and distal anastomosis were examined immunohistochemically. Presence of coagulation factor VII, and C3 complement factor were studied. The obtained results were analyzed statistically by means of t-Student test. Factor VII as well C3 were found in areas of both proximal and distal anastomosis. Concentration of all two substances in proximal and distal anastomosis was compared. No statistically valid differences in factor VII concentration in proximal and distal anastomosis were found, whereas amounts of C3 factor as well as degree of extracellular matrix infiltration were markedly higher in distal anastomosis.

Intraoperative hemostasis during kidney transplantation and the use collagen mesh dressing covered by fibrin glue (TachoComb).

In this paper we present influence of use of haemostatic dressing TachoComb, onto bleeding from surface of transplanted kidney. Kidney transplantation (KTX) seems to be main method of treatment of terminal renal failure. Enlarging number of KTX results in growing frequency of intra and postoperative complications. Hemorrhagic complications can impact clinical status of recipient and graft function. Haemostatic dressing was applied at 29 cases. Control group in which only gas compresses were used consisted of 25 patients. It was proved, that use of dressing from collagen mesh covered by fibrin glue TachoComb, after kidney transplantation diminished parenchymal bleeding and time necessary to get complete hemostasis.

Use of mesh fibrous dressing covered with fibrin glue (TachoComb) in hemostasis after vascular anastomoses in the groin.

We present in this paper application of haemostatic device TachoComb onto bleeding after vascular anastomosis of dacron vascular prosthesis (branch of aortobifemoral or bypass aortofemoral) with common femoral artery in the groin. Hemorrhagic complications have influence onto clinical status of operated patients. Haemostatic TachoComb dressing was applied at 30 cases and results were compared to control group consist of 25 cases, in which gas compresses were applied. Mean loss blood in group I with the usage of TachoComb was statistical characteristic (p < 0.003) smallest than in group II. Also mean time of hemostasis was shortest than in group II (p < 0.01). We proved that use of TachoComb limits bleeding from suture line connecting artery with vascular prosthesis.

The use of synthetic vascular prosthesis in the surgical treatment of secondary aorto-duodenal fistulas.

In this paper the methods with synthetic vascular prosthesis used in surgical treatment of the secondary aorto-intestinal fistula are presented. 10 cases of 22 patients treated in the years 1993-2003 for secondary aorto-intestinal fistulas as a complication of vascular prosthesis infection are analysed. In all patients the abdominal CT, scintigraphy with technetium 99m labeled leucocytes and endoscopy were performed. The patients underwent the operation of infected dacron prosthesis' replacement with silver/collagen coated prosthesis or extraanatomic bypass (subclavian to femoral). To close the intestinal fistula the duodenectomy with gastroenterostomy was performed or the duodenum was sutured and protected with the use of pedicled omentum. In 4 patients extraanatomic subclavian-femoral of polytetrafluoroethylene (PTFE) bypass was used. In these cases the intestinal surgery was composed of the partial duodenectomy with fistula excision and duodenal stumps formation followed by antecolic gastrojejunostomy with the Braun's enteroanastomosis and pyloroplasty. In this group 2 patients (50%) died in the follow up period. There were two extraanatomic bypass thromboses in the 30 days follow up and one amputation (25%). The infected vascular prosthesis was replaced with silver/collagen coated prosthesis in the 6 patients. In these cases duodenal fistula was closed with two layers of stitches and additionally protected with pedicled fragment of the greater omentum, which was sewn on the duodenum. In this group 1 patients (16.7%) died in the follow up period. In one case (16.7%) in 9 months after operation reinfection od silver prosthesis was observed. There were no significative differences (p = 0.45) in terms of early mortality between both group of patients. The treatment of the fistula is a difficult and hazardous surgical procedure, results of which are unpredictable.

The treatment of subclavian artery compression with the use of ringed polytetrafluoroethylene vascular prostheses.

UNLABELLED: In this paper the treatment of arterial complications of the Thoracic Outlet Syndrome (TOS) is presented. The investigation of 14 patients treated in the Department of Vascular, General and Transplantological Surgery of the Wroclaw Medical University for arterial complications of the TOS (as upper limb ischemia and/or the subclavian artery aneurysm in 14 patients) was performed. In case of complications associated with compression of the subclavian artery the operation consisted of resection of the first rib and accessory osseous and muscular pathological elements using supraclavicular and/or infraclavicular approach with implantation of externally supported ringed vascular polytetrafluoroethylene bypass (PTFE) were performed. The therapy results were estimated with use of The Disabilities of the Arm, Shoulder and Hand (DASH) questionnaire of American Academy of Orthopedic Surgeons. RESULTS: In case of upper limb ischemia the improvement of blood flow was obtained after the subclavian-brachial bypass implantation (5 patients). In this group the DASH score showed return to full activity. In case of subclavian artery aneurysm surgery (9 patients) the DASH scale revealed worsening of limb function in 4 patients during follow-up period. The optimal therapy of vascular complications is the multimodal treatment (reconstructive vascular procedure with decompressive surgery). The decompression of neurovascular bundle in vascular TOS should include the first rib resection in each case.

The use of minimally invasive videoscopic technique in large vessel and cardiac surgery. Does the potentially increased difficulty bring benefits to the patient?

We present the clinical case of a 63-year-old patient who underwent in the Department of Cardiac Surgery implantation of an aorto-bifemoral graft prosthesis and coronary artery bypass revascularization with application of less invasive off-pump technique. Graft selection (arterial grafts, venous grafts) is very important during qualification for coronary artery bypass revascularization. Minimally invasive saphenous vein harvesting was performed during the presented case. The endoscopic technique of vein harvesting is a relatively rarely applied technique during myocardial revascularization surgery. The concept of minimally invasive videoscopic technique is presented. There is a discussion on why the team decided to prolong duration of the case consisting of two major operations performed simultaneously. Minimally invasive videoscopic technique may have a significant positive impact on postoperative outcome in a selected group of patients.