178 research outputs found
High-temperature molten salt thermal energy storage systems
The results of comparative screening studies of candidate molten carbonate salts as phase change materials (PCM) for advanced solar thermal energy storage applications at 540 to 870 C (1004 to 1600 F) and steam Rankine electric generation at 400 to 540 C (752 to 1004 F) are presented. Alkali carbonates are attractive as latent heat storage materials because of their relatively high storage capacity and thermal conductivity, low corrosivity, moderate cost, and safe and simple handling requirements. Salts were tested in 0.1 kWhr lab scale modules and evaluated on the basis of discharge heat flux, solidification temperature range, thermal cycling stability, and compatibility with containment materials. The feasibility of using a distributed network of high conductivity material to increase the heat flux through the layer of solidified salt was evaluated. The thermal performance of an 8 kWhr thermal energy storage (TES) module containing LiKCO3 remained very stable throughout 5650 hours and 130 charge/discharge cycles at 480 to 535 C (896 to 995 F). A TES utilization concept of an electrical generation peaking subsystem composed of a multistage condensing steam turbine and a TES subsystem with a separate power conversion loop was defined. Conceptual designs for a 100 MW sub e TES peaking system providing steam at 316 C, 427 C, and 454 C (600 F, 800 F, and 850 F) at 3.79 million Pa (550 psia) were developed and evaluated. Areas requiring further investigation have also been identified
The comparison of two different embryo culture methods in the course of in vitro fertilization program.
The objective of the study was to compare two different embryo culture methods in the course of in vitro fertilization program by means of fertilization rate, embryo development, total time and cost. 98 patients undergoing assisted reproduction procedures due to infertility were analyzed. The inclusion criteria for the study: first IVF-ET program, at least 10 MII oocytes, no indications for ICSI. Oocytes were divided into two study groups: group A- open culture (oocytes placed in four-well dishes together, then inseminated and cultured in successive wells) and group B - a closed culture (oocytes placed in microdroplets, each embryo cultured separately). The fertilization rate was assessed around 18 hours from insemination. The embryos were classified into four classes. The best embryos were chosen for transfer. In the group A the fertilization rate obtained was lower than in group B (68% vs. 78%, respectively). The microdroplet culture required more time on the insemination day and on the second day of culture, while the four-well dish method required more time on the first day of culture and on the day of transfer. On analyzing the total cost of the above procedures (MI medium and oil costs) it occurred that the microdroplet culture was more expensive than the four-well dish method (due to the intake of paraffin oil). However, the difference was of no practical importance. In the conclusion, microdroplet culture gives a higher fertilization rate than four-well dish culture, probably due to a homogenous sperm distribution. Despite the differences in time outside the incubator and laboratory expenses (which are after all insignificant) microdroplet culture allows a better control over the embryo development. The embryos of best developmental potential can therefore be chosen for ET
Recurrent neuroendocrine adenoma of the middle ear: A case report
Les historiens, qui sont rarement des oiseaux de très bon augure pour la vitalité des croyances qu’ils étudient, ont beaucoup écrit, depuis les années 1970, sur le purgatoire, ce troisième « lieu » de l’au-delà catholique, situé entre enfer et paradis. Support d’une dévotion très populaire, il a connu en Europe trois pics successifs de popularité, à la fin du Moyen Âge, au xviie et au xixe siècles. Le dogme et la croyance ont ainsi puissamment structuré dans la longue durée le rapport aux morts dans les sociétés de culture catholique, en leur conférant une « utilité » particulière, à la fois matérielle, institutionnelle, pastorale et anthropologique, que cet article s’efforce d’explorer.Historians are people who rarely contribute to the continued vitality of the beliefs they study. Since the 1970’s they have written a lot about purgatory, the third place in the catholic beyond. This is situated in between hell and paradise. The belief was the basis of a very popular cult which peaked in popularity in three different periods, one at the end of the Middle Ages, another in the seventeenth and a third in the nineteenth century. The dogma and the belief in purgatory have thus for long periods powerfully structured the relation to the dead in catholic cultures and have given these a particular “usefulness” whether this concerns material, institutional, pastoral or anthropological aspects. The paper attempts to explore these issues
Satellite design optimization for differential lift and drag applications
Utilizing differential atmospheric forces in the Very Low Earth Orbits (VLEO)
regime for the control of the relative motion within a satellite formation is a
promising option as any thrusting device has tremendous effects on the mission
capacity due to the limited weight and size restrictions of small satellites.
One possible approach to increase the available control forces is to reduce the
mass of the respective satellites as well as to increase the available surface
area. However, satellites of these characteristics suffer from rapid orbital
decay and consequently have a reduced service lifetime. Therefore, achieving
higher control forces is in contradiction to achieving a minimum orbital decay
of the satellites, which currently represents one of the biggest challenges in
the VLEO regime. In this work, the geometry of a given reference satellite, a
3UCubeSat, is optimized under the consideration of different surface material
properties for differential lift and drag control applications while
simultaneously ensuring a sustained VLEO operation. Notably, not only the
consideration of sustainability but also the optimization with regard to
differential lift is new in literature. It was shown that the advantageous
geometries strongly depend on the type of gas-surface interaction and thus, two
different final designs, one for each extreme type, are presented. In both
cases, improvements in all relevant parameters could be achieved solely via
geometry adaptions
Molten Salt Thermal Energy Storage Systems
The feasibility of storing thermal energy at temperatures of 450 C to 535 C in the form of latent heat of fusion was examined for over 30 inorganic salts and salt mixtures. Alkali carbonate mixtures were chosen as phase-change storage materials in this temperature range because of their relatively high storage capacity and thermal conductivity, moderate cost, low volumetric expansion upon melting, low corrosivity, and good chemical stability. Means of improving heat conduction through the solid salt were explored
Robotic surgery in gynecology
Introduction of robotic surgery in the first decade of the 21 century was one of the biggest breakthroughs in surgery since the introduction of anesthesia. For the first time in history the surgeon was placed remotely from the patient and was able to operate with the device that has more degrees of freedom than human hand. Initially developed for the US Military in order to allow surgeons to be removed from the battlefield, surgical robots quickly made a leap to the mainstream medicine. One of the first surgical uses for the robot was cardiac surgery, but it is urology and prostate surgery that gave it a widespread popularity. Gynecologic surgeons caught on very quickly and it is estimated that 31% of hysterectomies done in the United States in 2012 will be done robotically. With over half a million hysterectomies done each year in the US alone, gynecologic surgery is one of the main driving forces behind the growth of robotic surgery. Other applications in gynecology include myomectomy, oophorectomy and ovarian cystectomy, resection of endometriosis andlymphadenectomy. Advantages of the surgical robot are clearly seen in myomectomy. The wrist motion allows for better, more precise suturing than conventional “straight stick” laparoscopy. The strength of the arms allow for better pulling of the suture and the third arm for holding the suture on tension. Other advantage of the robot is scaling of the movements when big movement on the outside translates to very fine movement on the inside. This enables much more precise surgery and may be important in the procedures like tubal anastomosis and implantation of the ureter. Three-dimensional vision provides excellent depth of field perception. It is important for surgeons who are switching from open surgeries and preliminary evidence shows that it may allow for better identification of lesions like endometriosis. Another big advantage of robotics is that the surgeon sits comfortably with his/her arms and head supported. This results in much less fatigue and therefore increases precision and potentially may decrease the number of medical errors. The eyes of the surgeon are directed at where the hands should be, which is more natural, allows for a more natural body position and mimics open surgery. Robot also enables better teaching, especially when two consoles are used. The surgeon and the student may be either sharing the instruments with two consoles or switching between one another. In a situation where the student operates, the surgeon can use the telestation to teach. Robotic simulator attached to one of the consoles allows students to practice after hours. In summary, surgical robot is a great tool, especially in gynecology but also in urology, cardiac surgery, general surgery and laryngology. The device will evolve and most likely with time will eliminate laparoscop
Blood pressure in postmenopausal women with a history of polycystic ovary syndrome
Polycystic ovarian syndrome (PCOS) is the most common endocrine disorder at reproductive age, affecting
6-10% of females in this group. The aetiology of this syndrome is not fully understood. Genetics, endocrinology
factors, and the influence of the environment are possible causes of this syndrome. PCOS is characterised by
menstrual disorders, hyperandrogenism, and abnormalities in ovarian morphology as well as metabolic disorders. PCOS increases the risk of overweight and obesity, diabetes, endometrial cancer, and cardiovascular
diseases such as hypertension along with all its long-term consequences. There are limited studies about cardiovascular disorders, especially hypertension, in postmenopausal women with a history of PCOS. The presented paper is an attempt to briefly summarise literature data concerning the influence of this disease on
the incidence of hypertension and blood pressure control in postmenopausal women. Women with PCOS more
often present features of metabolic syndrome and have increased cardiovascular risk factors including hypertension. The prevalence of hypertension is 2.5 times higher than in corresponding healthy peers. Furthermore,
hyperandrogenaemia is associated with elevated blood pressure independent of the patient’s age, insulin resistance, obesity, and dyslipidaemia. In view of this, these patients should be thoroughly screened for hypertensive
disorders and educated about the lifestyle modifications that could prevent hypertension later in life
Identification of Discolobium species indigenous to the Brazilian Pantanal ecosystem by microsatellite (SSRs) markers.
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Zastosowanie proteomiki do badań nad endometriozą
Despite significant scientific progress, etiology of endometriosis remains enigmatic. New advances in molecular biology have allowed the use of proteomics in demystifying this puzzling disease. Proteomics is a technology that permits the visualization of thousands of proteins inside a cell, tissue, or organism, and simultaneous observation of any alterations in protein expression and post-translational modification that may have important, clinical implications. Owing to its capacity to reveal the structural and functional properties of proteins, proteomics might illuminate the biology of the disease much better than genomics can. This state-of-the-art technology allows us to globally compare the expression and regulation profiles of proteins found in endometriosis with normal eutopic tissues (endometrium and peritoneum), as well as to compare those found in the different forms of endometriosis (i.e., peritoneal endometriosis, endometrioma, and adenomyoma). Proteomic analysis has been employed in endometriosis research in hope of discovering endometriosis-specific proteins, pathways, and potential biomarkers for precise, early detection. In recent years, several published studies have compared serum and peritoneal fluid protein content in women with and without endometriosis, as well as protein composition in endometrial implants, eutopic endometrium, endometriomas, menstrual blood and urine. It appears that use of proteomics could revolutionize our understanding of etiopathogenesis of the disease. Some of the identified proteins could indeed be responsible for the onset and progression of endometriotic implants. Because early stages of endometriosis may be difficult to diagnose, it would be of the utmost importance to identify specific biological markers of the disease. Additionally, specific implant proteins could become targets for molecular treatment of endometriosis. It is very challenging, however, to draw clear conclusions from the analysis of the obtained samples. First of all, the samples are usually pathologically confirmed to be endometriotic, but from a molecular stand point, the particular portion of the sample that is analyzed may matter greatly; none of the methods allow us to gain information about the molecular and pathological pattern of the same sample. Secondly, it is very difficult to define an ‘unaffected peritoneum’ as a control for the endometriotic lesions. Thirdly, the variety of options in each individual makes it difficult to see the molecular picture of the diseased area (such as the ovary or peritoneum) clearly. Ideally, the samples would be of greater value if obtained at an early age, that is, before puberty in each individual and then again when endometriosis occurs later in reproductive age. Such a project cannot be performed prospectively, although it may be considered as retrospective analysis of obtained material in some patients after successful chemotherapy due to oncological conditions.Etiologia endometriozy, pomimo wysiłku naukowców, wciąż nie została poznana w stopniu wystarczającym. Coraz częściej do badań nad tą jednostką chorobową wykorzystuje się wysoce specjalistyczne techniki molekularne - proteomikę. W ostatnich latach przeprowadzono wiele interesujących badań porównujących skład białkowy w różnych preparatach pochodzących od kobiet z endometriozą: surowicy krwi, płynie z jamy otrzewnowej, ogniskach endometrialnych na otrzewnej, torbieli jajnika, eutopowym endometrium oraz krwi miesiączkowej i moczu. Wydaje się, że zastosowanie badań proteomicznych mogłoby przyczynić się do uzyskania pewnych danych związanych z patogenezą endometriozy, dać klinicystom nowe narzędzia służące diagnostyce. Dodatkowo badania dotyczące znaczenia poszczególnych białek dają szansę na opracowanie nowych markerów, mających znaczenie dla oceny progresji czy ryzyka nawrotu. Dadzą również być może szansę na opracowanie nowych strategii terapeutycznych
Avaliação da capacidade de complexação da solução do solo comparando sistemas de plantio direto e convencional.
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