Tunable thermodynamic activity of La x Sr1-x Mn y Al1-y O3-δ (0 ≤ x ≤ 1, 0 ≤ y ≤ 1) perovskites for solar thermochemical fuel synthesis.

Nonstoichiometric metal oxides with variable valence are attractive redox materials for thermochemical and electrochemical fuel processing. To guide the design of advanced redox materials for solar-driven splitting of CO2 and/or H2O to produce CO and/or H2 (syngas), we investigate the equilibrium thermodynamics of the La x Sr1-x Mn y Al1-y O3-δ perovskite family (0 ≤ x ≤ 1, 0 ≤ y ≤ 1) and La0.6Ca0.4Mn0.8Al0.2O3-δ , and compare them to those of CeO2 as the baseline. Oxygen nonstoichiometry measurements from 1573 to 1773 K and from 0.206 to 180 mbar O2 show a tunable reduction extent, increasing with increasing Sr content. Maximal nonstoichiometry of 0.32 is established with La0.2Sr0.8Mn0.8Al0.2O3-δ at 1773 K and 2.37 mbar O2. As a trend, we find that oxygen capacities are most sensitive to the A-cation composition. Partial molar enthalpy, entropy and Gibbs free energy changes for oxide reduction are extracted from the experimental data using defect models for Mn4+/Mn3+ and Mn3+/Mn2+ redox couples. We find that perovskites exhibit typically decreasing enthalpy changes with increasing nonstoichiometries. This desirable characteristic is most pronounced by La0.6Sr0.4Mn0.4Al0.6O3-δ , rendering it attractive for CO2 and H2O splitting. Generally, perovskites show lower enthalpy and entropy changes than ceria, resulting in more favorable reduction but less favorable oxidation equilibria. The energy penalties due to larger temperature swings and excess oxidants are discussed in particular. Using electronic structure theory, we conclude with a practical methodology estimating thermodynamic activity to rationally design perovskites with variable stoichiometry and valence.

High Redox Capacity of Al-Doped La1-x Srx MnO3-δ Perovskites for Splitting CO2 and H2 O at Mn-Enriched Surfaces.

Perovskites are attractive candidates for the solar-driven thermochemical redox splitting of CO2 and H2 O into CO and H2 (syngas) and O2 . This work investigates the surface activity of La1-x Srx Mn1-y Aly O3-δ (0≤x≤1, 0≤y≤1) and La0.6 Ca0.4 Mn0.6 Al0.4 O3-δ . At 1623 K and 15 mbar O2 , the oxygen non-stoichiometry of La0.2 Sr0.8 Mn0.8 Al0.2 O3-δ increases with the strontium content and reaches a maximum of δ=0.351. X-ray photoelectron spectroscopy analysis indicates that manganese is the only redox-active metal at the surface. All La1-x Srx Mn1-y Aly O3-δ compositions exhibit surfaces enriched in manganese and depleted in strontium. We discuss how these compositional differences of the surface from the bulk lead to the beneficially higher reduction extents and lower strontium carbonate concentrations at the aluminum-doped surfaces. Using first principles calculations, we validate the experimental reduction trends and elucidate the mechanism of the partial electronic charge redistribution upon perovskite reduction.

Chemical looping of metal nitride catalysts: low-pressure ammonia synthesis for energy storage.

The activity of many heterogeneous catalysts is limited by strong correlations between activation energies and adsorption energies of reaction intermediates. Although the reaction is thermodynamically favourable at ambient temperature and pressure, the catalytic synthesis of ammonia (NH3), a fertilizer and chemical fuel, from N2 and H2 requires some of the most extreme conditions of the chemical industry. We demonstrate how ammonia can be produced at ambient pressure from air, water, and concentrated sunlight as renewable source of process heat via nitrogen reduction with a looped metal nitride, followed by separate hydrogenation of the lattice nitrogen into ammonia. Separating ammonia synthesis into two reaction steps introduces an additional degree of freedom when designing catalysts with desirable activation and adsorption energies. We discuss the hydrogenation of alkali and alkaline earth metal nitrides and the reduction of transition metal nitrides to outline a promoting role of lattice hydrogen in ammonia evolution. This is rationalized via electronic structure calculations with the activity of nitrogen vacancies controlling the redox-intercalation of hydrogen and the formation and hydrogenation of adsorbed nitrogen species. The predicted trends are confirmed experimentally with evolution of 56.3, 80.7, and 128 µmol NH3 per mol metal per min at 1 bar and above 550 °C via reduction of Mn6N2.58 to Mn4N and hydrogenation of Ca3N2 and Sr2N to Ca2NH and SrH2, respectively.

[Treatment of the elderly in the regional surgical department]. / Lécení senioru na okresním chirurgickém oddelení.

A retrospective study of health problems among patients aged 80 and over was performed in the in-patient Department of Surgery, Karviná Hospital, since 2005 to 2007. A total of 624 patients were hospitalized during the period under study, 174 males and 450 females, the M:F ratio being 1 to 2.6. Most hospital stays were categorized as acute--583 (i.e., 80.3%). A total of 295 operations (i.e.,40.6%) have been performed. The two major reasons for hospitalization were: 1) The most frequent reasons for hospital admissions and treatment were as follows: unexplained abdominal pain--60 cases, cholecystopathy--48 cases, hematemesis or melena--43 cases, abdominal hernias--29 cases, vomiting--26 cases, intestinal passage impairments--24 cases, diarrhoea--17 cases. 2). Injuries--274 cases (i.e., 37.7%), of which 121 cases presented with the primarily treated diagnosis of proximal femoral neck fracture (44.2% of all injuries). There were 35 cases (i.e., 4.8%) presenting with impairments of lower extremity arterial blood supply. Interestingly, the proportion of 'surgical' malignant tumours in this age group has been found relatively low: only 61 cases in the span of 3 years, 27 of the cases being colorectal carcinomas. Other reasons for hospital treatment were less common. There were only 34 social hospitalizations (4.7%). 295 patients have undergone operations (40.6%). 53 patients died, mostly as a result of circulatory failure. Of those 53, 16 patients had undergone surgical procedures (9 abdominal surgeries and 5 above-knee amputations). The present article discusses, among other issues, the nursing problems of caring for aged persons when there is a large amount of behavioural disorders due to advanced vascular dementia.

[Kidney transplantation from paediatric cadaveric donors to adult recipients (review article)]. / Transplantace ledvin od detských kadaverózních dárcu dospelým príjemcum. (Prehledový clánek).

The basic problem of all developed transplant programs is organs deficiency available for transplantation. There is an effort within last 10 years to get each organ for transplantation that it is supposed to be functional for several years. These problems also occur in the program of kidney transplantation. Apart from realizing of kidney transplantations from donors alive, which have an increasing tendency in Czech Republic (in 2001 more than 5%, in 2002 more than 10%), there is the only another possibility to get kidney grafts from non-ideal (suboptimal, marginal) donors. Both short-term and long-term results of kidney transplantation from non-ideal donors are comparable with the transplantation results from ideal donors. The kidneys from very young paediatric cadaveric donors, especially up to five years are the typical example of non-ideal graft. The article introduces the international position of the Czech Republic in organ procurement from cadaveric donors as well as in kidney transplantations. It shortly summarizes the history of kidney transplantations and at the same time it deals with realizing of kidney transplantation from paediatric cadaveric donors to adult recipients. The new division of kidney grafts from paediatric cadaveric donors into four groups according to their age is introduced. All at once the present surgical technique is described and the problems of some post-operative complications are discussed, especially the higher occurrence of primary graft non-function. The principle that kidneys from donor up to three years should be transplanted as a block to the single recipient is emphasized. In conclusion the author recommends, on the basis of his own experiences, the realizing of these transplantations.

[The results of kidney transplantation from very young paediatric cadaveric donors to adult recipients in Czech Republic in the years 1994-2001 (retrospective study of the Czech transplant centres)]. / Výsledky transplantací ledvin od malých detských kadaverózních dárcu dospelým príjemcum v Ceské republice v letech 1994-2001 (Retrospektivní studie ceských transplantacních center).

The results of kidney transplantation from very young paediatric cadaveric donors up to five years, which were transplanted to adult recipients, are evaluated in the first retrospective study of all Czech transplantcentres. In general, 42 of these transplantations were carried out during 1994-2001. In 28 cases single kidney was transplanted, in 14 cases en bloc graft of both children kidneys was transplanted. The reasons of kidney failure by recipients are usual (in 42.9% glomerulonephritis). An average age of the donors was 34.7 months (median 39 months). An average age of the recipients during transplantation was 42.6 years (median 43.5 years). All the kidneys were placed into retroperitoneum. As long as only single kidney was transplanted, the rules, already propagated by Salvatiera in 1970, were respected. At the transplantation of en bloc graft, Kinne's method with possible vessels elongation of the graft and with uretero-uretero anastomoses (in so called Ostrava modification) was used. The higher occurrence of the primary graft non-function (as 50% losses of all grafts) was confirmed in the study. Its reason was an acute thrombosis of vessels or rotation of graft stem. One-, three- and five-years patients and grafts survival were 97.6-90.5-90.5% and 76.2-73.8-73.8% actually. Patients survival are very good while grafts survival are average, momentarily a bit worse than national data published by the Czech Transplant Society, which determines one-, three- and five-years grafts survival with 90.3-82.9-75.5% and 79.1-71.1-65% actually. The kidney transplantation from paediatric cadaveric donors to adult recipients is acceptable under present allocated criteria, in case that some principles are kept. The study confirms the international experiences about rather higher incidence of surgical complications and primary graft non-function. In conclusion, some general references for reduction of complications, as well as for improvement of these transplantation results are introduced.

[Incidence of inguinal hernias]. / K problematice výskytu tríselných kýl.

Groin hernia operation is the third most frequent operation in the Czech republic. Early recurrence of the hernia after prime operation is a medical failure. The recurrences can arise after all types of operation. Incidence of recurrences, time factors of its genesis and treatment are discussed there.

[Basic principles of surgical treatment of recurrent inguinal hernias]. / Hlavní zásady chirurgického lécení recidiv tríselných kýl.

The incidence of the recurrences after groin hernia operation can be surprisingly high. Both basic principles of the surgical treatment (tension on, tension free) of this disease are known more than 30 years. It seems, that the latest endoscopic-laparoscopic proceedings have smaller recurrences. However long-term results are absent for more than 10 years from the prime surgery. In the report the basic principles of prime groin hernia surgery are mentioned, both classical transinguinal operation and endoscopic surgery. In the end the fundamental scheme is introduced--how to proceed in surgical treatment of groin hernia recurrences.

[The first kidney block transplantation in the Czech Republic--results]. / První transplantace bloku ledvin v Ceské republice--výsledek.

A case report of the fate of the first cadaveric pediatric kidney block transplantation into adult recipient in the Czech republic. The operation was done in Regional transplant centre in Faculty hospital Ostrava in February 1994. The whole postoperative period has been recapitulated since the operation to the end 2000. Pediatric kidney graft is functional 7 years after transplantation.

[Aneurysm of the superior mesenteric artery in a child]. / Aneuryzma horní mezenterické tepny u dítete.

A case report of the ruptured aneurysma of the superior mesenteric artery at 12-year-old girl which was successfully treated by resection and substitution by means of venous graft. There is illustrated good long-term result more than 7 years after operation. Superior mesenteric artery aneurysma diagnosis in childhood is very rare.

[Ureteroureteral end-to-side anastomosis in kidney transplantation--personal experience]. / Uretero-uretero anastomóza end to side u transplantací ledvin--nase zkusenosti.

The most widely used way of reconstruction of the urinary pathways in transplantations of the kidney is at present a ureteroneocysto anastomosis. In some patients this type of reconstruction is difficult, if not impossible (adhesions in the lesser pelvis of the recipient, atrophic urinary bladder, short ureter of the graft, transplantation of child kidneys). In these instances the authors indicated a uretero-uretero end-to-side anastomosis. The authors performed in 13 patients a total of 17 uretero-uretero end-to-side anastomoses. In six transplantation of child kidneys en bloc was involved. During the postoperative period one female patient developed a urinary fistula from the renal pelvis of the graft which healed after conservative treatment. End-to-side uretero-uretero anastomosis is a simple and safe way of reconstruction of the urinary pathways in renal transplantations.

[Reconstruction of the femoro-popliteal and peripheral portion in saphenous insufficiency]. / Náhradní rekonstrukce femoropopliteálního a periferního úseku pri nedostatku safény.

Implantation of a venous bypass is the best method of infraarticular and crural reconstructions. In 30%, however, a suitable saphenous vein is not available. If on account of severe ischemia revascularization is necessary, an alternative method must be selected. From a total number of 326 peripheral reconstructions with a distal anastomosis into the distal popliteal artery or crural artery the authors had to use instead of a long venous bypass a subsidiary reconstruction in 145 patients (44.6%). The authors implanted composite venous bypasses in 36 patients (24%), in 93 patients (64%) they combined a venous bypass with desobliteration of the superficial femoral artery and in 16 patients (11%) with an artificial prosthesis. For the end-to-end anastomosis of the prosthesis and vein the authors suggested a plastic operation by means of a venous patch which makes a short anastomosis possible with a smooth transit from a wide prosthesis into a narrow vein. The authors assume that in future ever more frequently the combination prosthesis and vein in the shape of a jump bypass will be preferred to other reconstructive methods, as it is relatively simple and rapid. Their hitherto assembled experience with this methods is favourable.

[Surgical treatment of post-traumatic thrombosis of the inferior vena cava]. / Chirurgická lécba poúrazové trombózy dolní duté zíly.

A 49-year-old man contracted a fracture of the 8th and 9th rib on the right side and developed after this injury thrombosis of the inferior vena cava in the renal and suprarenal portion and of both renal veins manifested clinically as nephrotic syndrome of obscure aetiology. Only detailed cavographic and CT examination revealed this thrombosis. Caval thrombectomy was performed according to Spencer's method because of concurrent phlebothrombosis of the left lower extremity. The patient is in a satisfactory condition with permanent Pelentan medication.

[Chemical lumbar sympathectomy]. / Chemická bederní sympatektomie.

After an account of historical facts the authors describe the technique of chemical lumbar sympathectomy. A 7.5% phenol solution in glycerol was used (7.5 ml). At the Surgical Clinic of the Institute for Postgraduate Medical Training of the Regional Hospital with Policlinic in Ostrava chemical lumbar sympathectomy was performed in 22 patients. No complications were observed during operation and during the postoperative period and in all patients the effect was favourable.

[Iatrogenic injuries of the abdominal aorta during surgery of intervertebral disks of the lumbar vertebrae]. / Iatrogenní poranení brisní aorty pri operacích meziobratlové ploténky bederních obratlu.

The authors present the case-histories of two successfully treated patients following injury of the infrarenal part of the abdominal aorta. The injury occurred during extirpation of sequestra of discs of lumbar vertebrae. Some problems of the tactics of surgical treatment are discussed.

[Arteriovenous shunt--a prerequisite for long-term hemodialysis therapy]. / Arteriovenózní shunt--nezbytná podmínka dlouhodobého hemodialyzacního lécení.

The authors give an account of the experience of their department with the establishment of arteriovenous fistulae during the preparation of patients for a dialyzation transplantation programme. In the course of 13 years a total of 685 a-v shunts were made. The results in 60 patients are evaluated in detail. These patients were treated in 1989 in the chronic dialyzation programme of the Ostrava dialyzation unit, focused on long-term patency of the fistulae. The cumulative patency of shunts up to one year is 83.3%, the long-term patency is 73.3%.

[Personal experience with the use of acute isovolemic hemodilution in vascular surgery]. / Nase zkusenosti s uzitím akutní izovolemické hemodiluce v cévní chirurgii.

The authors present their eight-year experience with acute isovolaemic haemodilution during operations on blood vessels in the aorto-femoro-popliteal region. They remind of basic physiological findings, present actual results, and based on their experience and data in the literature, they formulate the main principles of indications and implementation of haemodilution.

[The role of computer tomography in the diagnosis of aneurysms of the abdominal aorta]. / Uloha computerové tomografie v diagnostice aneurysmatu abdominální aorty.

The advantages of computer tomography are obvious. They include the non-invasive character of examination, the detection of aneurysms with a small diameter and the opportunity to check them systematically. Computer tomography is in the authors' opinion most effective in the differential diagnosis and for the assessment of the character of aneurysms--stable or unstable, and in particular in the diagnosis of initial stages of ruptures.