Wall Sampling of Suspensions from Liquid-solid Systems

Problem uzorkovanja suspendiranih čvrstih čestica kroz stijenku uređaja, kao i njihovog kontinuiranog odvoda iz određenog sustava prisutan je u mnogim procesima kemijske i srodnih industrija. Uspješno vođenje i kontrola procesa sa suspendiranim česticama zahtijeva poznavanje koncentracije tih čestica, kao i njihove raspodjele veličina. Zbog svoje jednostavnosti i prilagodljivosti na uvjete odvijanja procesa uzorkovanje kroz stijenku veoma je zastupljeno u industrijskoj praksi. U ovom radu dan je osvrt na čimbenike koji mogu uzrokovati pogreške tijekom postupka uzorkovanja suspendiranih čestica iz sustava čvrsto/kapljevito i udaljiti nas od postupka tzv. idealnog uzorkovanja. Izokinetičko, odnosno i neizokinetičko uzorkovanje suspenzija iz cijevnih sustava vrlo je dobro proučeno, kako eksperimentalno tako i teorijski. Međutim, mnogo manje je istovjetnih istraživanja koja se odnose na uzorkovanja iz miješalica. Pogreške koje se javljaju pri ovom postupku usko su vezane uz tromost čvrstih čestica, sudare čvrstih čestica sa stijenkom uzorkovala te uz strukturu toka kapljevine ispred otvora uzorkovala. Može se zaključiti da učinkovitost uzorkovanja tj. masena koncentracija čvrstih čestica u uzorku nije funkcija isključivo srednje koncentracije čvrstih čestica u sustavu, već značajno ovisi i o fizikalnim karakteristikama sustava čvrsto-kapljevito, geometrijskim karakteristikama uzorkovala, poziciji uzorkovanja te brzini kojom se ono izvodi.The problem of an adequate sampling from slurry handling equipment is present in many branches of the chemical and related industries. It is often very important to know the solid concentration and the particle size distribution in the apparatus of this kind, in order to control and operate them. For this purpose, wall sampling is widely adopted in industrial practice for its simplicity and versatility. Serious errors in measuring solids concentration can arise from unsuitable sampling. This work reports the main factors that may cause these deviations from ideal wall sampling during work with slurry handling equipment. Up to now, some authors have thoroughly studied the problem of isokinetic and anisokinetic sampling from slurry pipelines, both theoretically and experimentally. However, little work was dedicated to the withdrawal of solid suspensions from stirred vessels. The main sources of sampling errors occur because of particle inertia, particle bouncing effects and flow structure ahead of the sampling device. The results of experimental work of different authors indicate that the solid concentration in the sample, i. e. sampling efficiency, depends strongly on the sample tube design, withdrawal velocity and sampling device location as well

ESSENCE-Q: Slavic language versions for developmental screening in young children

Dejan Stevanovic,1 Rajna Knez,2,3 Tatjana Zorcec,4 Marija Anderluh,5 Jana Kodrič,5 Petar Petrov,6 Feriha Hadžagić Ćatibušić,7 Azra Deljković,8 Slavica Brkic Cvetkovic,1 Nikolina Vrljičak Davidovic,9 Radenka Kuzmanić Šamija,10 Ana Ðorić,11 Christopher Gillberg12 1Psychiatry Department, Clinic for Neurology and Psychiatry for Children and Youth, Belgrade, Serbia; 2Department of Child and Adolescent Psychiatry, Skaraborgs Hospital, Skövde, Sweden; 3Department of Psychiatry and Psychological Medicine, Faculty of Medicine, University of Rijeka, Rijeka, Croatia; 4Developmental Department, University Children’s Hospital, Skopje, Macedonia; 5Department of Child Psychiatry, University Children’s Hospital, University Medical Center Ljubljana, Ljubljana, Slovenia; 6Department of Child and Adolescent Psychiatry, University Hospital St Marina, Varna, Bulgaria; 7Pediatric Clinic, Clinical Center Sarajevo, Bosnia and Herzegovina; 8Psychiatry Department, Mental Health Center Pljevlja, Pljevlja, Montenegro; 9Department of Child and Adolescent Psychiatry, Clinical Hospital Center, Split, Croatia; 10Clinic for Children’s Disorders, Clinical Hospital Center, Split, Croatia; 11Center of Applied Psychology, Faculty of Humanity and Social Sciences, University of Rijeka, Rijeka, Croatia; 12Gillberg Neuropsychiatry Center, University of Gothenburg, Gothenburg, Sweden Purpose: The Early Symptomatic Syndromes Eliciting Neurodevelopmental Clinical Examinations – Questionnaire (ESSENCE-Q) was developed as a brief screener to identify children with developmental concerns who might have neurodevelopmental disorders (NDDs). This study aimed to translate the ESSENCE-Q into south Slavic languages, namely, Bosnian, Bulgarian, Croatian, Macedonian, Montenegrin, Serbian, and Slovenian, and to evaluate its psychometric properties for screening purposes in clinical settings. Patients and methods: In the study, the ESSENCE-Q was completed for 251 “typically developing” children and 200 children with 1 or more diagnosed NDDs, all aged 1–6 years. Internal consistency and construct validity were tested first, followed by generating receiver operating characteristic curves and the area under the curve. Optimal cutoff values were then explored. Results: The Cronbach’s α coefficients were 0.91, 0.88, and 0.86 for ESSENCE-Q parent-completed form, and the telephone and direct interview forms administered by trained nurse or specialist, respectively. The 3 versions produced area under the curve values (95% confidence interval): 0.96 (0.93–0.99), 0.91 (0.86–0.95), and 0.91 (0.86–0.97), respectively. An optimal cutoff for ESSENCE-Q parent-completed form was found to be ≥3 points, while for the telephone and direct interviews, it was ≥5 points. Conclusion: We found adequate measurement properties of the south Slavic languages versions of the ESSENCE-Q as a screener for NDDs in clinical settings. This study provided additional data supporting sound psychometric properties of the ESSENCE-Q. Keywords: early screening, questionnaire, autism, intellectual disabilit