Rješavanje problema kemijske procesne industrije potaklo je stvaranje nove znanstvene discipline koja raspolaže vlastitim alatima (paradigmama) temeljenim na znanstvenim spoznajama različitih
...disciplina. Nova disciplina, kemijsko inženjerstvo, omogućava početkom dvadesetog stoljeća analizu različitih procesa petrokemijske i velike kemijske industrije, dijeleći ih na manji broj jediničnih operacija. Kasnije, kemijsko inženjerstvo proširuje koncepciju jediničnih operacija, dijeleći proces do sve niže i niže razine, primjenom u reakcijskom inženjerstvu. Istodobno, potreba za optimiranjem procesa uključuje sustavski pristup. Umjesto traženja detalja, sintezom procesa osmišljavaju se više razine organizacije. Primjena računala postaje ključni element pri modeliranju i vođenju procesa. Metode kemijskog inženjerstva šire se i na druga područja, pri čemu disciplina zadržava iste temeljne karakteristike.
Promjene na globalnom tržištu potiču nove trendove u istraživanju i evoluciju u poučavanju, jer razvoj proizvoda definiranih uporabnih svojstava postaje ključno područje djelovanja, koje podrazumijeva integrirani pristup pojavama i procesima koji se odvijaju u različitim veličinskim mjerilima radi moguće pretvorbe molekula u korisni proizvod na procesnoj razini.
Naglasak je na prikazu razvoja discipline u Hrvatskoj s posebnim osvrtom na osobe koje su u pojedinim razdobljima najviše pridonijele prihvatu i širenju novih spoznaja.
Hot-melt coating process (HMCP) was applied to develop a lipid based oral controlled release matrix system (tablet) to deliver highly aqueous soluble drugs using paracetamol as a model drug. Granules ...prepared from paracetamol and particular filler were coated with different levels of lipid and then compressed into tablets to get controlled/sustained delivery of the drug over an optimum period. Process parameters were optimized with particular focus on fluidization pattern during HMCP proposing a ‘design space’ with ‘Quality by Design’ (QbD) concept in mind. The results demonstrated that the granule composition influenced the drug release pattern, and the rate of release could be manipulated by varying the amount of lipid in the formulation. The in vitro release profile of the drug was pH-independent and the most promising release profile was obtained from tablets prepared from granules with the water-soluble filler, lactose, and coated at 9% (w/w) level with a lipid, glyceryl behanate. In vivo plasma profiles of the drug were predicted from the in vitro release profile data by convolution analysis which confirmed that the lactose based formulation with 9% (w/w) lipid coating on the granules would be suitable for controlled delivery of the drug over a period of 12 h making the formulation suitable for highly water soluble drug candidates like paracetamol with twice daily dose regimen. Moreover, the dissolution data adequately fitted into Higuchi model suggesting that the drug release occurred predominantly by diffusion.
Solving important problems of chemical and process industries stimulated the creation of a new scientific discipline, chemical engineering, which apart from other disciplines includes firm ...theoretical foundations, core subjects taught to entering students, widely adopted textbooks and journals. The new discipline, at the beginning of the 20th century, provided a way of analyzing the wide variety of processes in terms of small "unit operations". Later, the largely empirical approach of the unit operations was broadened by molecular explanations of macroscopic phenomena. It was not long before chemical engineering extended the operation approach to chemical reaction engineering. At the same time, process optimization prompted the system approach. Instead of looking for details, higher levels of organization were recognized by synthesis. The use of computers has become the key element in process modeling and control. The methods of chemical engineering have extended to other fields, while the discipline keeps the same basis and characteristics.The changes on the global market stimulate new trends in research and education. Product development has become an important segment of the discipline, which presumes an integrated approach to the phenomena and processes at different time and length levels following the possible transfer from molecule to product at process level.This paper mainly deals with the development of this discipline in Croatia, with a preview of the persons that contributed to the acceptance and propagation of the new concepts.
The aim of this research was to check the validity of the weighed system of criteria for evaluating the actual quality of water polo players proposed by Hraste, Dizdar and Trninić. The authors have ...determined the attributes of the measurement instrument for assessment of the overall performance efficiency of elite water polo players. Based on the determined descriptive indicators, on the coefficients of the relative importance of criteria, and on the degree of the objectivity level (interobservers' agreement) of the expert evaluations, it can be concluded that the measuring attributes (objectivity and sensitivity) for most of the criteria are in accordance with their relative importance coefficients for a particular position in the game. Consequently, a structure of relevant criteria is proposed for each play action position in the water polo game. The established instrument for evaluation the actual quality of the elite water polo players is a precondition to establish the professional system orientation, but it would also mean and a hypotheses for adequate design tactic model of play and a process of sports preparation. In succeeding steps of developing the system of criteria and its applicability, the latent structure of the criteria variables should be determined as well as overall importance of criteria with respect to the game of water polo.
Abstract
Ascorbic acid has been fluidized and microencapsulated with three different hydrophobic coating materials by the top-spray method. The experiments were conducted with polymethacrylate ...coating material formulated as a water dispersion, and ethyl-cellulose and waxy coating material both formulated as organic solutions. Characteristics of the fluidized bed procedure in conical geometry have been determined by estimation of two parameters: bed porosity and total pressure drop. A satisfactory agreement between experimental and calculated values has been reached. The following properties of the micro-encapsulated ascorbic acid have been determined: core content, bulk and tapped density, crystal size distribution prior and after microencapsulation, surface morpholgy and release profile. The comparison and evaluation of different hydrophobic coating materials have been performed on the basis of these findings.
The goal of the research was to define experts opinion about adequate criteria for water polo players' actual quality evaluation and to determine experts opinion about weight coefficients (ponders) ...of the here defined criteria across the playing positions in the game of water polo. Based upon the expertise performed by ten water polo professionals, the relative importance coefficients with regard to playing positions in the game were determined for twenty seven performance evaluation criteria. High degree of interobserves' agreement was obtained regarding all positions (from 0.93 to 0.96). In concordance with the obtained results the particular playing positions were explicitly described, as well as the similarities and the differences between them were determined from the aspect of the single criteria importance. The research results could be usefully applied by the water polo practitioners for the selection and follow-up of players during training programme implementation, and for programming, control and evaluation of transformational effects.
High-shear and fluid-bed processes were used for granulation of dolomite powder into agrochemical product. In this paper, comparative study of the granulation process focuses on the observation of ...granule size distribution (GSD). Considerable difference between high-shear and fluid-bed GSDs is analyzed with process kinetics. Simulation of dynamic development of GSD is achieved with application of a 1-D discretized population balance and Equi-Partition of Kinetic Energy (EKE) coalescence model. The used
approach indicates for both processes (high-shear and fluid-bed granulation) the presence of coalescence growth as a dominant mechanism in the dolomite granulation process. Deviations between simulated and real GSDs signify the probable existence of other granulation mechanism(s). A posteriori approach by the integral method was used for coalescence rate constant estimation. The generated kinetic considerations represent a valuable step towards a comprehensive perspective of dolomite granulation and implementing
the acquired knowledge in real-life agrochemical granulation.
There is not in Argentina publications regarding the presentation of patients with COVID-19 requiring hospitalized and emergency care in vulnerable populations (lower incomes and less education tend ...at greater risk for poor health status and healthcare access), and it has few reports in developing countries. The objective is to determine whether in the care of vulnerable patients, to succeed against COVID-19, multiple public health tools and interventions will be needed to minimize morbidity and mortality. The study is a prospective cohort investigation of patients with lab-confirmed COVID-19, who required to any of the Health Centers response from April 8, 2020, to August 18, 2020. In Buenos Aires Metropolitan Area (AMBA), April 8, 2020 the virus was identified in patients hospitalized in the "Southeast Network" (SN), AMBA. SN covering an area of 661 square kilometers, with 1.8 million inhabitants residing in urban, and rural areas. A total of 14 health centers with different levels of care complexity provide care to patients in the region. The information of each patient with COVID-19 evaluated by SN, was incorporated in an Epidemiological Dashboard. The investigation was designed and reported with consideration of observational studies in epidemiology. We describe the hospitals presentation and care of persons who required SN response and were ultimately diagnosed with COVID-19. From April 8, 2020, to August 18, 2020, were included 1495 patients with lab-confirmed COVID-19 in SN. A total of 58% patients were men, and the mean age (SD) was 48.9 (15.59) years. Eighty one percent patients with pre-existing diseases, most frequent hypertension and diabetes, but hypertension, chronic lung disease, and cardiovascular disease presented higher risk. A total of 13% were hospitalized in Intensive Therapy Unit. The mortality of the cohort was 9.77%. Mortality was higher for patients aged 65 or more (OR 5.09), and for those had some pre-existing disease (OR 2.61). Our observations are consistent with reports demonstrating older persons, and those with comorbidities have the highest risk of mortality related to COVID-19. However, unlike other reports from developed or some developing countries, the mortality in our study is lower. This finding may be related to age of our cohort is younger than other published. Also, the health system was able to respond to the demand.
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