Dynamic Mechanical Behaviour of Polymer Bonded Nd-Fe-B Composite Materials

Magnetic composite materials with varied content of Nd-Fe-B particles in epoxy matrix are examined from a dynamic mechanical perspective. Structural, viscoelastic and magnetic properties of composites have been observed using Scanning Electron Microscope (SEM), Dynamic Mechanical Analysis (DMA) and Super Quantum Interference Device (SQUID) magnetometer, respectively. Experimental results show that magnetic properties and corresponding dynamic mechanical behaviour depend on packing density. Also, results observed by predictive mathematical models suggest that maximal packing factor has a direct impact on elastic behaviour of composites. [doi:10.2320/matertrans.M2011218

Hibdridni Nd-Fe-B/barijum-ferit magnetni materijali sa epoksi matricom

Lately, there has been great attention paid to the research of bonded hybrid composites with improved dynamic mechanical capacities capable of replacing bonded Nd-Fe-B magnetic materials, by using cheaper (ferrite) materials instead of the Nd-Fe-B powder while retaining the satisfying values of the maximum magnetic energy. The objective of this study is to assess how different contents of Nd-Fe-B and/or barium ferrite particles can affect morphological, dynamic mechanical and magnetic properties of bonded composite materials. The interactions between employed magnetic powders and the interactions between magnetic powders and polymer binder are considered. For the examination of the magnetic behaviour, a vibrating sample magnetometer (VSM) is used. Different shapes and sizes of the obtained hysteresis loops are used for comparison and prediction of the polymer bonded materials properties. The homogeneous distribution of the magnetic particles in the polymer matrix is validated using scanning electron microscopy (SEM). The elastic and damping behavior examined by dynamic mechanical analysis (DMA) show improved properties for hybrid composite materials.Istraživački trend u oblasti polimerom vezanih (bonded) Nd-Fe-B magnetnih materijala se reflektuje kroz razvoj bonded hibridnih kompozita sa poboljšanim dinamičko-mehaničkim svojstvima i primetno nižoj ceni zbog zamene skupe Nd- Fe-B legure jeftinijim magnetnim materijalima (ferit) uz postizanje zadovoljavajućih vrednosti maksimalne magnetne energije. Cilj ovog rada je da ukaže i predvidi uticaj različitog sadržaja Nd-Fe-B i/ili barijum feritnih čestica na morfološka, dinamičko mehanička i magnetna svojstava bonded magneta. Posmatrane su i analizirane interakcije između magnetnih prahova, kao i interakcije između magnetnih prahova i polimernog veziva i njihov uticaj na finalna svojstva bonded magneta. Za ispitivanje magnetnog ponašanja korišćen je vibraconi magnetometar (VSM). Različite veličine i oblici dobijenih histerezisnih krivih su poređeni i korišćeni za predviđanje svojstava ispitivanih kompozitnih materijala. Homogena raspodela magnetnih čestica u polimernoj matrici je potvrđena korišćenjem skenirajućeg elektronskog mikroskopa (SEM). Elastična svojstva i svojstvo prigušenja oscilacija ispitivano je korišćenjem dinamičko mehaničke analize (DMA) koja ukazuje na poboljšana svojstva kod hibridnih kompozita

Houses Based on Natural Stone; A Case Study—The Bay of Kotor (Montenegro)

The Bay of Kotor, in its exceptional natural conditions, thanks to its geographical location and influenced by historical events, saw the development of rural settlements that are historically, artistically and culturally worthy of recognition. These stone settlements were acquired completely spontaneously, keeping the same pace as the settling, and transformed to some degree due to contemporary social movement and migration. Up until the middle of the 20th century, structures on the coastline in general were built by applying the same verified methods, which remained unchanged for centuries. Unreinforced stone walls as load-bearing vertical elements, coupled with wooden floor joists attached in a traditional way are typically present in the stone architecture of the Adriatic region and karst areas in general. The construction characteristics of the stone houses built in such a way meet all needs in terms of strength, thermal insulation, and are suitable for the coastal climate of this region. The fast-paced development in the past 50 years, the inadequate legal protection of residential buildings in the Bay of Kotor, poverty, and the new rich have brought about the devastation of not only buildings built in traditional architecture styles themselves, but also the urban landscape of the bay. Throughout the Bay of Kotor, buildings built in traditional architecture styles are nowadays more and more rare to see in their original shape—houses outside of cities but which display all characteristics of civic coastal houses and buildings free of rigid style rules, even though closely in contact with them. Regardless of efforts to preserve the heritage inherited by our ancestors, cultural monuments and houses referenced here deteriorate on a daily basis due to troubles and neglect

Comparison of oncologic outcomes between elective partial and radical nephrectomy in patients with renal cell carcinoma in CT1B stadium

Background/Aim. In renal cell carcinoma (RCC), the choice of surgical technique, radical (RN) or partial nephrectomy (PN), is still center-dependent because there are still no absolute recommendations for this approach. The aim of this study was to analyze the oncological aspects, time until recurrent disease appears, and cancer-specific survival in patients with RCC in T1bN0М0 stadium depending on the type of surgical procedure, PN or RN technique. Methods. In a clinical observational study, data of 154 patients operated at the Clinic for Urology, Military Medical Academy, Belgrade, Serbia with a mean follow-up period of no less than five years were analyzed. Patients were divided into two groups; a group of patients with RN and a group of patients with PN. The inclusion criteria were: renal tumors 4–7 cm, histopathological confirmation of RCC, absence of metastasis, and normal serum creatinine. Exclusion criteria included: the presence of other malignancies, solitary functional kidney or comorbidities that can compromise renal function, bilateral tumors, or unilateral multiple tumors. Results. The study analyzed data from 154 patients, 97 (63%) RNs, and 57 (37%) patients that underwent PN. Analyzing cancer-specific survival in four patients with RN, there was a disease advancement that led to a lethal outcome, and one PN patient died as a result of local relapse and distant metastasis. Conclusion. Based on our results, PN is a good and safe treatment option for patients with RCC in T1b stadium. PN offers a similar tumor control and better cancer specific survival

Milk quality at purchases in the area of Kozarska Dubica

У исхрани становништва Републике Српске, као и у сусједним земљама, млијеко и производи од млијека задовољавају добар дио потреба за високо вриједним протеинима и минералним материјама, а са друге стране производња млијека и мљекарство као привредна грана имају важно учешће у остваривању прихода људи, који се баве пољопривредом. Млијеко при откупу треба да испуњава услове квалитета прописане Правилником о квалитету свјежег сировог млијека и условима за рад овлашћене лабораторије (”Службени гласник Републике Српске” бр. 81/15). При откупу млијека испитују се физичко-хемијски параметри (маст, протеини, сува материја, сува материја без масти, густина, степен киселости, тачка мржњења, као и укупан број микроорганизама и број соматских ћелија). Циљ рада је био да се на основу ретроспективне анализе резултата, добијених из мониторинга квалитета сировог млијека са четири фарме, смјештене на подручју општине Козарска Дубица оцијени квалитет млијека при откупу. Материјал је представљало 200 узорака сировог млијека са 4 фарме. У узорцима млијека су испитани: хемијски параметри (млијечна маст, лактоза, протеини, сува материја, сува материја без масти), тачка мржњења, број соматских ћелија и укупан број микро- организама. Резултати су добијени испитивањем сировог млијека примјеном инструменталних метода (MilkoScan за одређивање хемијског састава млијека, Fossomatic за одређивање броја соматских ћелија, BactoScan за одређивање укупног броја микроорганизама и криоскоп за одређивање тачке мржњења). Свих 200 узорака сировог млијека са четири фарме на подручју општине Козарска Дубица, у погледу хемијског састава, су задовољавали захтјеве прописане правилником. У погледу броја соматских ћелија сирово млијеко све четири фарме је задовољавало захтјеве прописане за млијеко стандардног квалитета. Просјечан број микроорганизама у сировом млијеку на фармама 1, 2 и 3 није задовољавао захтјеве за млијеко стандардног квалитета. Просјечан број микроорганизама у млијеку на фарми 4 прелази границу од 100.000 cfu/ml и износи 125.000 cfu/ml. На основу анализе броја микроорганизама у сировом млијеку може се закључити да је потребно извршити едукацију музача на фарми 4 у вези са хигијеном муже и музне опреме, као и поступања са млијеком након муже, у циљу смањења укупног броја микроорганизама у сировом млијеку.Milk and milk products provide a large portion of the needs for high valuаble proteins and minerals in the diet of population in the Republic of Srpska, as well as in neighboring countries and on the other hand milk production and dairy industry, as agricultural branch take an important part in achieving the income of people dealing with agriculture. Milk at purchases should meet the quality requirements according to the Rulebook of the Quality of Fresh Raw Milk and the Conditions for the Work of an Authorized Laboratory (Official Gazette of the Republic of Srpska No. 81/15). Physical and chemical parameters (fat, proteins, total solids, total solids not fat, density, acidity, freezing point, total number of microorganisms and somatic cell counts) should be examined at prchases. The aim of the study was to be based on a retrospective analysis of the results obtained from the monitoring of the quality of raw milk from four farms, located in the municipality of Kozarska Dubica assess the quality of milk at purchases. The material represented 200 raw milk samples from four farms. Milk samples were examined: for chemical parameters (milk fat, lactose, proteins, total solids, total solids not fat), the freezing point, the somatic cell counts and total bacterial count. The results were obtained by examining raw milk using instrumental methods (MilkoScan for determination of the chemical composition of milk, Fossomatic for determinination of somatic cell counts, BactoScan for determing the total bacterial count and the cryoscope fordeterminination of the freezing point). All 200 raw milk samples from 4 farms in the Kozarska Dubica municipality, met the requirements prescribed for the quality by the rulebooks in terms of chemical composition Regarding the somatic cell counts in raw milk, all four farms met the requirements prescribed for an standard class of milk. The average number of bacteria in raw milk at farms 1, 2 and 3 does not meet the requirements for an standard milk class. The average number of bacteria in milk at farm 4 exceeds the limit of 100.000 cfu/ml and amounts to 125.000 cfu/ml. Based on the analysis of the number of microorganisms in raw milk, it can be concluded that training of milking staff at farm 4 is necessary in connection to the milking and milking equipment hygiene, as well as milk process after milking, in order to reduce the total bacterial count in the raw milk.Zbornik kratkih sadržaj

Effects of Rashig rings placed in interplate spaces and the rheological properties of the liquid phase on power consumption in a gassed reciprocating plate column

The power consumption in a gassed reciprocating plate column with Rashig rings placed in interplate spaces increases with both increasing vibration intensity and content of solid particles but decreases with increasing the superficial gas velocity, regardless of the rheological properties of the liquid phase. Under the same operating conditions, the power consumption is higher when the column is filled with a non-newtonian liquid than with distilled water

Significance of the correlation between serum-prostate specific antigen and the percentage of prostate cancer volume in postoperative biochemical progression

Introduction/Objective. Radical prostatectomy (RP) is the best form of treatment of patients with locally confined prostate cancer (PC). Biochemical progression (BP) of the disease occurs in 27–53% of patients after RP. The aim of our analysis was to assess the significance of the correlation of preoperative prostate-specific antigen (PSA) values and the percentage volume of PC in biochemical progression in patients with RP and the biopsy Gleason score of 6 and 7. Methods. The analysis included the results of treatment of 228 patients with the committed radical retropubic prostatectomy for localized PC in the 2007–2011 period. According to the Gleason grade system values, three groups were identified – 6 (3 + 3), 7 (3 + 4) and 7 (4 + 3). According to the preoperative PSA values the following three groups were determined and monitored: ≤ 4 ng/ml, 4.1–10 ng/ml, and ≥ 10.1 ng/ml. Biochemical progression was defined as two consecutive increases of PSA values ≥ 0.2 ng/ml after RP. The percentage of tumor volume (PTV) is determined by a visual assessment of the percentage of PC in each microscopic sample. Four PTV groups were determined: 0–5%, 6–25%, 26–50%, and 51–100%. Results. Biochemical progression was registered in 19 patients. Most frequent PTV in the group of patients with BP and from biopsy and RP was 6–50%, an average of 30%. Conclusion. Our study showed predictive significant connections between preoperative PSA values and the values of PTV after operational treatment and that these are independent parameters in the assessment of treatment results

Complications of radical and partial nephrectomy for renal cell carcinoma up to 7 cm

Background/Aim. Renal cell carcinoma (RCC) is the third most frequent urological carcinoma. Radical nephrectomy (RN) is considered as the gold standard in the treatment of localized RCC, but recently the use of minimally invasive techniques are more frequently used. The aim of this study is to determine is there a difference in the incidence of complications in the group of patients treated by RN and partial nephrectomy (PN) for renal cell carcinoma up to 7 cm. Methods. The retrospective study included the analysis of the medical history of patients surgically treated in the six years period. The inclusion criteria were RCC size up to 7 cm and no detectable metastasis. The exclusion criterion was the presence of a bilateral tumor. Intraoperative and early postoperative complications were followed-up. The Clavien- Dindo grade system was used for classification of surgical complications. Results. In six years period 481 (76.35%) radical transperitoneal nephrectomies and 149 (23.65%) partial nephrectomies were performed. Bilateral RCCs were verified in 2.06% (13/630), an initial metastatic disease in 15.8% (100/630) and lymph node involvement in 7.14% (45/630) of the patients and their data were not included in analysis. Therefore, data from 120 patients with RN and 97 patients with PN who fulfill inclusion criteria were analyzed. Complications were recorded in 29.5% (64/217) of patients. Significantly less patients had complications in the RN group [22.5 % (27/120)] compared to the PN group [38.1% (37/97)] (p = 0.006). These complications were mostly grade I and II. Complications grade III and IV were only present in the group of patients treated by PN. Conclusion. Based on our data in selected patients with renal cell carcinoma in stage T1, PN is a proper and safe choice. The patient must be involved in making the definitive decision of modalities of surgical treatment

Hybrid Nd-Fe-B/barium ferrite magnetic materials with epoxy matrix

Lately a great attention has been paid to the research of bonded hybrid composites with improved dynamic mechanical capacities capable of replacing bonded Nd-Fe-B magnetic materials, by using the cheaper (ferrite) materials instead of the Nd-Fe-B powder while retaining the satisfying values of the maximal magnetic energy. The objective of this study is to assess how different contents of Nd-Fe-B and/or barium ferrite particles can affect morphological, dynamic mechanical and magnetic properties of bonded composite materials. The interactions between employed magnetic powders and the interactions between magnetic powders and polymer binder are considered. For the examination of the magnetic behaviour, a vibrating sample magnetometer (VSM) is used. Different shapes and sizes of the obtained hysteresis loops are used for comparison and prediction of the polymer bonded materials properties. The homogeneous distribution of the magnetic particles in the polymer matrix is validated using the scanning electron microscope (SEM). The elastic and damping behaviour examined by the dynamic mechanical analysis (DMA) show improved properties for hybrid composite materials