Search

The effect of vibratory mill induced mechanical activation on the change of the particle size, crystallinity and the phase transformations of the minerals present in the activated material, was studied with the purpose of decreasing of the sintering temperature of talc (Mg3Si4O10(OH)2) as raw material which is the basic component of the steatite ceramics. The aims of the conducted investigation were, also, increasing of the reactivity of the comminuted raw material and establishing of the optimal activation period. The properties of the activated talc induced by mechanical force were expressed in form of the grain inertia change which was measured by means of automatic grain counter. Mechanically activated grains are the most convenient mineral form for physical concentration since the energy change of the mill-material system is recorded on them. The effect of dry grinding on the structure, particle size and shape of talc was studied by means of XRD, DTA and SEM/EDS methods. Activation of talc produced an increase of the starting surface area value progressively from 4.5 m2/g up to a maximum of 108.5 m2/g achieved at 30 min. A subsequent decrease of rate of surface area change and the rate of size reduction were observed following the prolonged grinding. Talc activated in vibratory mill for optimal 30 min showed properties which positively influence the decrease of sintering temperature and the increase of the sintering rate of steatite ceramics. [Projekat Ministarstva nauke Republike Srbije, br. 172057, br. 45008 i br. 33007]

Amount of fly ash which is and yet to be generated in the coming years highlights the necessity of developing new methods of the recycling where this waste can be reused in significant quantity. A new possibility for fly ash utilization is in high-temperature application (thermal insulators or/and refractory material products). As such, fly ash has to adequately answer the mechanical and thermal stability criteria. One of the ways of achieving it is by applying mechanical activation procedure on fly ash. In present study, fly ashes from two different power plants were mechanically activated in a planetary ball mill. Mechanically treated fly ashes were cemented with two different binders: standard Portland cement and high-aluminates cement. Physico-chemical analysis and investigation of mineralogical components of composites are emphasized, due to the changes occurred in fly ash during mechanical activation and sintering of composites. Macro-performance of the composites was correlated to the microstructure of fly ash studied by means of XRD and SEM analysis. Thermal stability of crystalline phases was investigated with DTA. Highlight was placed on determination of relationship between mechanically activated fly ash and obtained composites microstructure on one side and behavior of sintered composites on the other side. [Projekat Ministarstva nauke Republike Srbije, br. 172057, 45008 and a project F-198, financed by Serbian Academy of Sciences and Arts]

Interest for application of hydrometallurgical processes in a processing of complex sulphide ores and concentrates has increased in recent years. Their application provides better metal recoveries and reduced emission of gaseous and toxic ageneses in the environment. The kinetics and mechanism of sphalerite leaching from complex sulphide concentrate with sulphuric acid and sodium nitrate solution at standard conditions was presented in this paper. The influences of temperature and time on the leaching degree of zinc were investigated and kinetic analysis of the process was accomplished. With temperature increasing from 60 to 90°C, the zinc leaching increased from 25.23% to 71.66% after 2 hours, i.e. from 59.40% to 99.83% after 4 hours. The selected kinetic model indicated that the diffusion through the product layer was the rate-controlling step during the sphalerite leaching. The activation energy was determined to be 55 kJ/mol in the temperature range 60-90°C. XRD, light microscopy and SEM/EDX analyses of the complex concentrate and leach residue confirmed formation of elemental sulphur and diffusion-controlled leaching mechanism.

Determination of chlorophyll content as an indirect method of estimating the productivity of vegetation represents a good way to gain an understanding of the photosynthetic regime of plants. Physiological investigations of chlorophyll and carotenoid content in the uppermost internode of several wheat cultivars were carried out at the outset of the flowering phase. The dependence of chlorophyll and carotenoid content on the fertilization variant was established at that time. The tested wheat cultivars were grown under conditions of five fertilization variants. The content of chlorophyll a, chlorophyll b, and total chlorophyll (Chl a+b) was measured and carotenoid content was determined on each variant. The results indicate that chlorophyll and carotenoid content depended on the presence and ratio of mineral elements in the substrate. This is demonstrated by the variant with unfertilized soil, where chlorophyll and carotenoid content in all cultivars was lowest. The variant of fertilization with N and P turned out to be most favorable. The next most favorable variant was the one with nitrogen alone, and it was followed by the variant with N and K.

Recently, concern about the environmental impact of drug analysis methods has increased significantly. Reversed-phase high-performance liquid chromatography (RP-HPLC), the predominant technique in drug analysis, relies heavily on organic solvents such as acetonitrile, which is known for its chromatographic efficiency, but also for its toxicity and flammability. To address these concerns, it is essential to minimize the use of toxic organic solvents. The aim of this study is to explore greener RP-HPLC modifications and evaluate their applicability in the pharmaceutical industry. Methods were developed for the separation of dronedarone hydrochloride and its degradation products based on experimental design, including micellar liquid chromatography (MLC), b-cyclodextrin (CD) modified RP-HPLC and ultra-high performance liquid chromatography (UHPLC). The eco-friendliness of these methods was assessed using the analytical eco-scale score, green analytical procedure index (GAPI) and analytical greenness (AGREE). AGREE appears to be the most suitable, as it revealed the greatest differences between the compared methods, as well as insights into critical aspects of the methods. UHPLC and b-CD modified RP-HPLC have been shown to be superior to MLC, and both methods can be a good choice, depending on whether the ease of implementation or energy efficiency is considered to be a more important criterion.

Phyllosilicate mineral pyrophyllite is predominantly used in the ceramic industry because it exhibits high refractoriness. Due to its thermal transformation into mullite, pyrophyllite is stable at elevated temperatures, making it a suitable mineral additive for refractory non-shaped materials and various ceramic shaped products. In this study, pyrophyllite is employed as 50 % clay replacement in the ceramics and up to 30 % cement replacement in mortars. Physico-mechanical properties were investigated. The firing shrinkage in the ceramics treated at 1200 °C was reduced by pyrophyllite addition. Pyrophyllite acted as additional pozzolana during cement hydration. Within the microstructure, it formed micro-reinforcement in the shape of crystalline folia, which improves the mechanical properties of ordinary Portland cement, high aluminate cement, and blended cement mortars. The investigation proved the efficiency and suitability of pyrophyllite employed as a substitution for clay in ceramics and a cement replacement in mortars.

Introduction. Alzheimer's disease is the most common form of dementia. Apraxia can be one of the symptoms of Alzheimer's disease. Apraxia is defined as an acquired deficit in the execution of movements that cannot be explained by motor or sensory impairments. Aim. The main aim of this research is to determine the types of apraxia in people with Alzheimer's dementia and to point out the importance of early rehabilitation of these patients. Method. The sample consists of 15 patients with Alzheimer's dementia (amnestic type - multiple domains) aged from 50 to 85 years. In addition to the free interview, which follows predetermined principles, a neurological clinical assessment of motor skills and sensitivity and a neurobehavioral assessment of appearance, behavior, and emotions were conducted. The examination was conducted according to the established criteria at the Antamedica Polyclinic in Belgrade. Results. The results of our study show that patients with Alzheimer's disease are impaired in both the first and second stages: time orientation, attention, arithmetic, remembering, naming, writing, and copying figures. On the other hand, other cognitive functions are relatively well preserved in these stages of the disease. Patients with Alzheimer's disease have an impaired ability to understand spoken and written language. In contrast, no deficits were found on the verbal-visual discrimination test. Conclusion. Assessment of apraxia has become an important aspect of neurodegenerative diseases and a main indicator for psychotherapy and occupational therapy, contributing to the quality of life of the elderly, primarily with cognitive decline.

Dysfunctions underlining type 2 diabetes mellitus (DM2) evolution are insulin resistance and beta-cell secretory insufficiency. Practical but reliable beta-cell function (BCF) testing is still elusive. Methods of BCF measurement include the homeostasis model assessment (HOMA), glucagon stimulation test (GST), oral glucose tolerance tests (OGTT), intravenous glucose tolerance tests (IVGTT), meal tolerance tests (MTT) and the hyperglycemic clamp procedure. Oral tests have the advantage of simpler use and superior approximation of real-life stimulation inclusive for incretin activation effects. The advantage of the test meal over the OGTT incudes a more adequate simulation of nutrients effect on incretin secretion. Therefore, a standardized test meal (STO) would best reflect the spike in insulin secretion after a meal in real life. Conclusion: Standardized test meal, as potent stimulus of C-peptide secretion, is a promising simple and naturalistic alternative to in vivo assess beta-cell function in an affordable outpatient setting, through analysis of C-peptide response in newly diagnosed diabetic patients, as potent stimulus of C-peptide secretion.

High-pressure liquid chromatography (HPLC) is a technique of paramount importance in the analysis of pharmaceuticals because of its ability to separate moderately polar to less polar compounds, such as drugs and related substances.High-pressure liquid chromatography (HPLC) is a technique of paramount importance in the analysis of pharmaceuticals because of its ability to separate moderately polar to less polar compounds, such as drugs and related substances. The concept of green analytical chemistry (GAC) aims to provide more environmentally friendly and safer analytical methods in terms of reagents, energy, and waste. One of the major challenges of GAC is to find an appropriate approach to evaluate the greenness of analytical methods. An extension of GAC, called white analytical chemistry (WAC), has been introduced to consider not only environmental friendliness, but also other aspects that contribute to the sustainability of methods, such as analytical and economic or practical efficiency. HPLC methods are intrinsically not green, due to the high consumption of toxic organic solvents and the resulting generation of large amounts of toxic waste. Fortunately, there are many approaches to overcome the non-green character of HPLC methods. In this article, various modifications of the HPLC methods that increase its environmental friendliness are presented, as well as the various tools used to evaluate environmental friendliness. In addition, the new concept of white analytical chemistry is presented.

Introduction. Lymphomas are malignant diseases of the lymphocyte lineage. There are two basic types of lymphoma: Hodgkin's lymphoma (HL), whose main characteristic is the presence of Reed-Sternberg cells, and non-Hodgkin's lymphoma (NHL), which presents a heterogeneous group of diseases, and depending on the growth rate and the course of the disease, they can be indolent (slow-growing) and aggressive (fast-growing). Follicular lymphoma (FL) is the most common indolent form of NHL, while diffuse large B-cell lymphoma (DLBCL) is the most common aggressive form. Case report. The study presents a case of NHL, DLBCL, localized in the cervix, histopathologically diagnosed in a 35-year-old woman who, after a cervical biopsy, was histopathologically diagnosed with mild dysplasia (CIN1/L-SIL) of the cervical epithelium and, after that, an infection with human papillomavirus (HPV) subtypes 16 and 31 was proven. The diagnosis of DLBCL was histopathologically confirmed on a conical section of the vaginal portion of the uterus, after which the disease was treated with eight cycles of chemotherapy according to the RCHOP protocol. Conclusion. The coexistence of CIN1/L-SIL and NHL is random. However, this fact may cause the concomitant cervical lymphoma to be overlooked since the lymphoma is usually subepithelial if biopsies are not taken adequately and if HPV serotyping of the biopsy sample is not performed.

Background/Aim. Complications of diabetes mellitus (DM) in the eye are the leading cause of blindness in the world. Although research on eye complications of DM is mainly focused on retinal damage, changes in the cornea are also associated with DM. Central corneal thickness (CCT) reflects the metabolic status of the cornea and is also affected by DM. Knowledge of CCT changes that occur within DM is important for accurate IOP measurement, diagnosis, and monitoring of patients with glaucoma. The aim of the study was to examine the effect of DM type 2 on the central corneal thickness. Methods. The study was designed as a clinical, cross-sectional, observational study. It consists of 96 patients, divided into two groups. The first group consisted of 49 patients diagnosed with DM type 2. The second group was the control group and consisted of 47 healthy subjects. The DM group was divided into subgroups depending on the status of diabetic retinopathy, the length of DM treatment, and the levels of glycosylated hemoglobin (HbA1C). Results. A statistically significant difference in CCT was observed among DM patients and the control group. Analyzing only DM patients, the highest CCT values were observed in patients who had HbA1C > 7.0%, as well as those who have treated DM for more than 15 years, with a statistically significant difference in relation to the corresponding patient sub-groups (p = 0.002 and p = 0.037, respectively). No statistically significant difference was observed depending on the status of retinopathy. Intraocular pressure (IOP) was statistically significantly higher in patients with DM compared to the control group. Conclusion. Our research demonstrated that the status of retinopathy had no statistically significant influence on CCT. Knowing that the increase in CCT also affects the measured IOP values, this research will be useful in better understanding and control of the patients who have glaucoma in addition to DM type 2.

Introduction/Objective Acute myocardial infarction (AMI) and acute ischemic cerebral infarction (AICI) are both leading causes of death around the world. A simultaneous occurrence of these conditions is called a cardio-cerebral infarction (CCI). We are presenting a case of CCI detected in the prehospital setting as a rarity. Case report: The patient presented is a 78-year-old woman with simultaneous development of AMI and AICI. The diagnosis of a suspected CCI was made in the prehospital setting based on hetero anamnestic data, physical examination findings and ST-segment elevation. At the hospital, additional testing (MDCT of the endocranium, echocardiogram and high troponin levels) confirmed both diagnoses. The patient was treated with fibrinolytic therapy but developed cardiac arrest. After extensive CPR efforts, the patient was pronounced dead. Conclusion: It is necessary to create national guidelines for the diagnosis and treatment of this emergency condition as soon as possible. In the meantime, an individualized approach to each patient is the best policy.

As the production of metal-based nanomaterials increases, it is inevitable that nano-scale products and byproducts will enter the aquatic environment. In terms of global production, the most abundant nano-oxides are TiO2, CeO2 and Fe3O4 nanoparticles. Chironomus riparius is commonly used for ecotoxicological assessment and defining its histopathological biomarkers that showcase the toxic effect of tested nanoparticles should lead to a better understanding of the consequences of nanomaterial accumulation in aquatic ecosystems. In this study, a histological description of the digestive and excretory systems as well as the fat body structure of C. riparius larvae is provided. In addition, potential histological biomarkers of nano-oxide toxicity were determined based on the obtained histopathological alterations in organs. Vacuolization was observed in epithelial cells of midgut region I that were treated with nano-Fe3O4 as well as in Malpighian tubules treated with nano-Fe3O4 and nano-CeO2. Larvae exposed to nano-TiO2 showed alterations in the fat body and midgut region II tissue architecture. Additionally, shortening of the intestinal brush border was determined in groups exposed to nano-Fe3O4. These results reveal the high sensitivity of these organs, which can be used as biomarkers in histopathological assessment and therefore lead to further improvement of existing methodology in ecotoxicological studies.

Design of Experiments (DoE) is an indispensable tool in contemporary drug analysis as it simultaneously balances a number of chromatographic parameters to ensure optimal separation in High Pressure Liquid Chromatography (HPLC). This manuscript briefly outlines the theoretical background of the DOE and provides step-by-step instruction for its implementation in HPLC pharmaceutical practice. It particularly discusses the classification of various design types and their possibilities to rationalize the different stages of HPLC method development workflow, such as the selection of the most influential factors, factors optimization and assessment of the method robustness. Additionally, the application of the DOE-based Analytical Quality by Design (AQbD) concept in the LC method development has been summarized. Recent achievements in the use of DOE in the development of stability-indicating LC and hyphenated LC-MS methods have also been briefly reported. Performing of Quantitative structure retention relationship (QSRR) study enhanced with DOE-based data collection was recomended as a future perspective in description of retention in HPLC system.

Micro-silica is a highly efficient mineral additive whose role is reflected in improvements of microstructure packing, strength and durability of non-shaped composite building materials such as concrete and mortar. A comparative study of performances of rendering mortars with different quantities of micro silica was conducted. The experimental program included production of reference mortar based on Portland cement and quartz sand (CM) and three mortars with 5, 10, and 15 % addition of micro silica (SCM-5, SCM-10, and SCM-15). The effect that micro silica addition has on the thermal behavior and mechanical properties of mortars was discussed. Hydration mechanisms and thermally induced reactions were studied at temperatures ranging from ambient to 1100 °C by differential thermal analysis. The results were supported by X-ray diffraction analysis. The cementing efficiency of micro silica was assessed by cavitation erosion test. The changes in the morphology of mortar samples prior and upon cavitation testing were monitored by means of the scanning electron microscope imagining. It was found that 5 % of superfine micro silica (SCM-5 mortar) has positive effects on mechanical strengths (15 % increase in compressive strength) due to microstructure densification arising from the successive filling of voids by the micro silica. Addition of micro silica also improved the cavitation erosion resistance in comparison with reference cement mortar (SCM-5 showed cavitation velocity as low as 0.09 mg/min). This qualifies mortars with micro silica addition as building materials which can be safely employed in potential hydro-demolition environment.

Introduction/Objective. Vocal folds are the most common primary site of laryngeal carcinoma. Advancement in diagnostic and therapeutic modalities have provided better prognosis for patients with early glottic carcinoma. We aimed to report the role of videolaryngostroboscopy (VLS) in early diagnosis of vocal fold carcinoma. Methods. Prospective controlled study included 300 dysphonic patients admitted to the tertiary medical center for microlaryngoscopy with biopsy. All patients underwent stroboscopic examination prior to biopsy. VLS findings were classified according to Hirano into four stages, with an adynamic vocal fold segment and absence of vocal fold vibration, suspected for vocal fold carcinoma at stage IV. Histopathological findings have been graded according to Ljubljana classification into simple hyperplasia, abnormal hyperplasia, atypical hyperplasia, and carcinoma in situ. Results. Analysis of VLS findings showed that 41.67% of patients (n = 125/300) had asymmetrical and irregular vocal fold vibration with a mucosal wave reduction (VLS stage III), while an adynamic vocal fold segment and absence of vocal fold vibration (VLS stage IV), suspected for vocal fold carcinoma, was noticed in 17.33% of patients (n = 52/300). Histopathology report showed that vocal fold carcinoma was verified in 5.6% of patients in VLS stage III (n = 7/125), while VLS stage IV carcinoma was detected in 26.92% of patients (n = 14/52). Adynamic segment or entire nonvibrating vocal fold finding predicts early glottic carcinoma with a sensitivity of 66.77%, specificity of 86.4%, and moderate diagnostic accuracy (AUC = 0.844). Conclusion. VLS plays an important role as a timely indicator for microlaryngoscopy with biopsy in diagnosis of vocal fold carcinoma.

Introduction. Laryngeal schwannomas are rare benign neuro-genic tumors. They are usually localized in the supraglottic portion of the larynx. We reported a rare case of laryngeal schwannoma with a focus on clinical presentation, diagnosis and management. Case report. A 61-year old male patient with a 3-year history of hoarseness underwent telescopic examination which revealed an oval submucosal tumefaction of the left ventricular fold extending over the left vocal fold toward the right ventricular fold. Multislice computed tomography showed a 22 x 15 mm well defined, oval heterodense mass in the region of the left ventricular fold, extending toward the left vocal fold and the posterior commissure of the larynx, with signs of initial compression lesion of the thyroid cartilage. Biopsy and histopathology revealed a primary benign encapsulated mesenchymal tumor, while immunohistochemistry analysis confirmed schwannoma diagnosis. The patient underwent tracheotomy and left hemilaryngectomy, with complete removal of the tumor. There were no signs of recurrence at the six-month follow-up. Conclusion. Schwannomas are rare among benign tumors of the larynx and might grow for years before being diagnosed. Biopsy with histopathology analysis is used to confirm the diagnosis of laryngeal schwannoma, although extreme care should be taken during biopsy. Treatment consists of complete surgical excision; the surgical approach depends on the size and localization of the tumor, as well as on the presence of a peduncle.

Bismuth (III) sulfide has been widely researched in recent years due to its application, but little emphasis has been placed on research regarding its behavior at elevated temperatures. This is of great importance, considering that bismuth, in the form of Bi2S3, is found in copper sulfide concentrates and is considered one of the most harmful components, along with lead, arsenic and antimony. The removal of these substances is one of the basic tasks in the processes of pyrometallurgical extraction of copper, in order to obtain a high purity metal. In order to better understand the behavior of bismuth (III) sulfide during oxidation at elevated temperatures, this paper characterized the synthesized sample of Bi2S3 at room temperature and the oxidation products at 500 °C by X-Ray diffraction (XRD), as well as thermodynamic, thermal and kinetic analysis of the oxidation process of Bi2S3 at elevated temperatures. In order to understand the behavior of Bi2S3 during oxidation and the distribution of oxidation products, phase stability diagrams in the Bi-S-O system were constructed at different temperatures and the values of the Gibbs free energy change at 400 °C and 1000 °C were calculated. Kinetic analysis of Bi2S3 oxidation process was performed by Kissingers method in non-isothermal conditions.

This experimental study was conducted with an aim to investigate the effect of the elevated temperature on the mineral phase composition, microstructure and mechanical properties of the thermal insulation lightweight concretes. The first group of experimental concretes was based on the expanded vermiculite and expanded perlite used as lightweight aggregates (in 65 wt%) in combination with either ordinary Portland cement or refractory calcium aluminate cement. The mix-design of the second group of concretes comprised standard quartz aggregate, vermiculite or perlite as aggregate replacement (25 wt%) and binder (PC or CAC). A total of 10 concrete mix-designs were fabricated in form of 40×40×160 mm samples which were submitted to heat-treatment at 400°, 600°, 800° and 1000°C upon standard 28-days period of curing and hardening. The changes in crystallinity and mineral phase composition induced by temperature were monitored by X-ray diffraction technique. Microstructural visualizations of the non-fired and fired concrete samples were conducted by scanning electron microscopy accompanied with EDX analysis. The results indicated that despite the decrease in compressive strengths upon firing, investigated lightweight concretes can be categorized both as thermal insulators and structural materials.