Istraživanje utjecaja pripreme površine osnovnog materijala na svojstva toplinski naštrcanog sloja

Using specimens, a research was conducted to determine the influence of the base material surface preparation for 42CrMo4 on the final coating, prior to actual thermal spraying. During thermal spraying, an Al-Ni-alloy was used as an interlayer before the actual coating with Cr-Mo-Ni. The surface hardness and the hardness distribution across the thickness of the sprayed coating were measured and the structure of respective sprayed coatings was photographed. A comparison of experimental results enabled the identification of the particular material preparation method with an optimal ratio of the satisfactory coating thickness and its hardness.Na uzorcima je istraživan utjecaj kvalitete pripreme površine osnovnog materijala 42CrMo4 prije naštrcavanja na svojstva toplinski plinski naštrcanog sloja. Pri naštrcavanju je kao međusloj korištena legura Al-Ni, dok je za završni sloj korištena legura Cr-Mo-Ni. Izvršena su ispitivanja površinske tvrdoće, toka tvrdoće po debljini naštrcanog sloja, te odgovarajuća snimanja struktura naštrcanih slojeva. Usporedbom rezultata ispitivanja utvrđena je priprema površine osnovnog materijala kod koje se postiže prihvatljiva debljina naštrcanog sloja uz postizanje zadovoljavajućih tvrdoća u naštrcanom sloju

On rationality of nonnegative matrix factorization

Nonnegative matrix factorization (NMF) is the problem of decomposing a given nonnegative n × m matrix M into a product of a nonnegative n × d matrix W and a nonnegative d × m matrix H. NMF has a wide variety of applications, including bioinformatics, chemometrics, communication complexity, machine learning, polyhedral combinatorics, among many others. A longstanding open question, posed by Cohen and Rothblum in 1993, is whether every rational matrix M has an NMF with minimal d whose factors W and H are also rational. We answer this question negatively, by exhibiting a matrix M for which W and H require irrational entries. As an application of this result, we show that state minimization of labeled Markov chains can require the introduction of irrational transition probabilities. We complement these irrationality results with an NP- complete version of NMF for which rational numbers suffice

Effect of litter type and perches on footpad dermatitis and hock burn in broilers housed at different stocking densities

The aim of the study was to assess the effect of litter type and environmental enrichment on the occurrence of footpad dermatitis and hock burns in broilers housed at low and high stocking densities. Chopped straw and sand were used as litter, and perches as environmental enrichment. Low and high stocking density implied 12 chickens/m2 and 20 chickens/m2, respectively. The study sample was divided into four groups of 50 birds, which were observed during a six-week fattening period. A significantly higher rate of severe footpad dermatitis was recorded in the group of chickens raised on sand at high stocking density, compared with low stocking density, whereas no significant difference was found between the groups of chickens raised on straw at different stocking densities. The rate of footpad dermatitis was also significantly higher in the group of chickens raised on sand at high stocking density, compared with chickens raised on straw at the same stocking density. There were no group differences in the occurrences of hock burns and perching. However, a significant negative correlation was recorded between perching and the occurrence of footpad dermatitis and hock burns. According to the occurrence of footpad dermatitis and hock burns, the study results suggested that chopped straw and sand were equally acceptable as litter for broilers, yet sand should be avoided at high stocking densities. There was no effect of stocking density and litter type on perching, but perches as a form of environmental enrichment proved efficient in reducing the rate of footpad dermatitis and hock burns.Keywords: chickens, contact dermatitis, environmental enrichment, housing, san

Septic sacroiliitis with iliacus muscle abscess – a case report

Prikazali smo slučaj 26 godina starog, prethodno zdravog muškarca s radiološki verificiranim septičkim sakroileitisom i apscesom lijevog ilijačnog mišića u tijeku stafilokokne sepse. Bolest se prezentirala naglim nastupom visokog febriliteta praćenog zimicama i tresavicama te bolovima u donjem dijelu leđa i lijevom kuku. Standardnom laboratorijskom obradom kod prijama nađena je lagano ubrzana SE 26 mm/1 h (uz porast na 60 mm/1 h trećeg dana), povišene vrijednosti CRP 123 mg/L, blaža leukocitoza 11,1 s neutrofilijom 78 % u DKS, blaža hipoproteinemija 61 g/L i hipoalbuminemija 33 g/L uz povišene vrijednosti frakcije alfa 1 (6,8 %) i alfa 2 (11,2 %) globulina u elektroforezi bjelančevina i fibrinogena 7,74 g/L te uredne ostale rutinske laboratorijske nalaze. Izolacija Staphylococcus aureusa iz hemokulture omogućila je ranu etiološku terapiju, a scintigrafijom skeleta i potom ciljanom radiografskom snimkom i kompjuteriziranom tomografijom (u daljnjem tekstu CT) sakroilijačnog zgloba locirano je mjesto upalnog procesa. Primijenjena antimikrobna terapija (vankomicin i ciprofloksacin parenteralno 2 tjedna, cefazolin parenteralno 4 tjedna, cefaleksin peroralno 3 tjedna) rezultirala je potpunim kliničkim oporavkom uz gotovo potpunu regresiju promjena na kontrolnim radiološkim snimkama. Septički sakroileitis izrazito je rijetka komplikacija u tijeku stafilokokne bakterijemije te smo iz toga razloga željeli prikazati bolesnika koji je uspješno liječen konzervativnom terapijom.We present a case of a 26-year-old previously healthy young male with radiologically confirmed septic sacroiliitis and left iliacus muscle abscess during staphylococcal sepsis. The disease onset was sudden with high fever, chills and shivering accompanied by pain in the lower back and left hip. Standard laboratory analysis on admission revealed moderately increased sedimentation rate 26 mm/1h (increasing up to 60 mm/1 h on the third day), elevated CRP 123 mg/L, mild leukocytosis 11.1 with neutrophilia 78 % in differential blood count, mild hypoproteinemia 61 g/L and hypoalbuminemia 33 g/L with elevated alpha-1 (6.8 %) and alpha-2 (11.2 %) globulins in protein electrophoresis and fibrinogen 7.74 g/L. Other routine laboratory tests were normal. The isolation of Staphylococcus aureus from blood culture has enabled early etiological therapy. Skeletal scintigraphy and targeted radiographic imaging as well as computed tomography of the sacroiliac joint revealed the location of the inflammatory process. Administered antimicrobial therapy (vancomycin and ciprofloxacin parenterally for 2 weeks, cefazolin parenterally for 4 weeks, cephalexin perorally for 3 weeks) resulted in full clinical recovery with almost complete regression of the changes observed on radiological images taken during follow-up visit. Septic sacroiliitis is an extremely rare complication during staphylococcal bacteremia and for this reason we decided to report a case that was successfully treated with conservative therapy

Neuroretinitis associated with cat-scratch disease: a case report

U studenom 2003. godine u Centralnoj prijamnoj ambulanti Klinike za infektivne bolesti »Dr. Fran Mihaljević«, Zagreb liječena je bolesnica s vitritisom i stražnjim uveitisom oba oka te neuroretinitisom lijevog oka, nastalim tijekom bolesti mačjeg ogreba (BMO). Slabljenje vida nastalo je istovremeno s otokom limfnog čvora u aksili, tri tjedna nakon ogreba mačke. Nakon pregleda u jednoj zagrebačkoj klinici za očne bolesti, bolesnica je upućena u našu Kliniku radi etiološke dijagnostike i preporuke za antimikrobno liječenje. Idućeg dana hospitalizirana je na Klinici za očne bolesti. Za vrijeme hospitalizacije liječena je azitromicinom peroralno tijekom pet dana prema preporuci infektologa, uz lokalnu i parenteralnu terapiju kortikosteroidima. Bolest je imala povoljan ishod. Ovo je prvi slučaj neuroretinitisa nastalog tijekom BMO koji je dijagnosticiran u ovoj Klinici, u suradnji s oftalmolozima. Dijagnoza se temeljila na epidemiološkoj anamnezi, regionalnom limfadenitisu s odgovarajućim citološkim nalazom punktata i serološkoj potvrdi protutijela na Bartonellu henselae.In November 2003, a 32-year-old female patient with vitritis and uveitis (pars planitis) of both eyes and neuroretinitis of the left eye, associated with cat-scratch disease (CSD) was treated at the Central Admissions Department of the University Hospital for Infectious Diseases »Dr. Fran Mihaljevic«, Zagreb. Impaired vision occurred simultaneously with axillar lymph node swelling, three weeks after cat scratch. After the patient was examined at the Ophthalmology Clinic in Zagreb, she was referred to our Hospital for etiological diagnostics and recommendation for antimicrobial treatment. The following day the patient was hospitalized at the Ophthalmology Clinic. During hospitalization she was treated with azithromycin p.o. for five days according to recommendation by the infectious disease specialist, with local and parenteral corticosteroid therapy. The disease had favorable outcome. This is the first case of neuroretinitis associated with CSD that was diagnosed in our Hospital in collaboration with colleagues ophthalmologists. The diagnosis was based on epidemiological data, regional lymphadenitis with corresponding cytological finding and serological confirmation of antibodies to Bartonella henselae