Experimental Study and Digital Analysis of Flammable Dust Granularity

Cel: W niniejszym artykule przedstawiono wyniki badań doświadczalnych oraz analizy cyfrowej ziarnistości pyłów palnych poddawanych testom parametrów wybuchowości w Zespole Laboratoriów Procesów Spalania i Wybuchowości CNBOP-PIB. W artykule opisano wyniki analizy sitowej pyłów, takich jak aluminium, kakao, likopodium, czy bułka tarta oraz problemy występujące podczas przesiewania pyłów w celu zbadania ich ziarnistości. Metodyka: Ze względu na przedmiot artykułu, oprócz badań doświadczalnych, wykorzystano mikroskop, aparat fotograficzny z adapterem do mikroskopu oraz komputer w celu opracowania alternatywnej metody badania ziarnistości pyłów. Wobec dużej różnorodności właściwości napotykanych materiałów nie jest możliwe wytypowanie jednej tylko metody analizy sitowej, którą można by zastosować do wszystkich badanych pyłów palnych. Pyły te różnią się właściwościami zarówno fizycznymi, jak i chemicznymi, takimi jak gęstość, kruchość, kształt ziarna, właściwości kohezyjne czy magnetyczne. Podstawowym problemem wynikającym z tych właściwości jest odpowiedni dobór parametrów oraz techniki ich przesiewania. Dla każdego materiału indywidualnie określić należy optymalny czas przesiewania, amplitudę wstrząsania, czy częstotliwość ręcznego ostukiwania, które niekiedy okazuje się konieczne. Wyboru parametrów dokonuje się empirycznie, co niekiedy bywa bardzo czasochłonne. Następnie dokonano analizy cyfrowej fotografii cząstek pyłu. Metoda ta opiera się na analizie fotografii cyfrowej z wykorzystaniem darmowego programu Image-J. W metodzie tej zdjęcie poddawane jest obróbce i analizie cyfrowej w celu uzyskania obrazu binarnego o określonym progu. Wyniki: Próby badania ziarnistości z wykorzystaniem jedynie metody cyfrowej okazały się znacznie bardziej czasochłonne. Główną przyczyną były duże niedokładności, skomplikowany proces przygotowania próbki, wykonania zdjęć ułatwiających późniejszą obróbkę oraz sam proces obróbki graficznej. Przetworzenie każdej z fotografii wymaga rozdzielenia złączonych ze sobą cząstek pyłu lub usunięcia fragmentów problematycznych, co w przypadku kilkudziesięciu zdjęć zajmuje wiele roboczogodzin. Wnioski: Na podstawie uzyskanych wyników metody nie można uznać za skuteczną alternatywę dla analizy sitowej. Przyczyną takiego stanu rzeczy są rozbieżności w wartościach średnicy sitowej oraz średnicy pozornej – dwu różnych sposobów określania ziarnistości pyłu w wymienionych wyżej metodach badawczych. Metoda pozwala jednak w pewnym stopniu usprawnić metodę analizy sitowej, pozwalając wstępnie oszacować ziarnistość danego pyłu, wybrać odpowiedni zestaw sit, a także wartości nasypowe pyłu.Aim: This paper presents the experimental study and digital analysis of flammable dust granularity performed in the Combustion Processes and Explosion Lab at the Scientific and Research Centre for Fire Protection (CNBOP-PIB). It contains experimental results of sieve analysis of several dusts such as aluminum, cocoa, lycopodium and breadcrumbs. It notices some problems identified during the screening of dust in order to examine its granularity. Methodology: Except some experimental work during the study the authors also used the laboratory microscope, camera with adapter for microscope and a computer in order to develop an alternative test method for granularity measurement. Due to a large variety of material properties it is not possible to nominate only one sieve analysis method that can be applied for all the combustible dust types. These dusts have large variety of properties both physical and chemical, such as density, fragility, grain shape, cohesive or magnetic properties. The main problem arising with these properties is suitable selection of parameters and sieving technique. For each material there is a need to determine individually the optimal sieving time, shaking amplitude or the frequency of manual tapping, which sometimes turns out to be necessary. Parameter selection needs to be made empirically, which sometimes can be very time consuming. The alternative method is based on the analysis of digital photography using the open source Image-J software. In this method, the image was processed in order to obtain a binary image with a specific threshold. Results: Granularity testing using only a digital method proved to be much more time consuming. The main reason was the large discrepancies in the results due to errors in all phases of work, such as the complicated process of preparation of the sample shots to facilitate further processing and graphics processing process itself. The processing of each of the photo requires the separation of accumulated dust particles or to remove problematic fragments, which in case of several tens of pictures takes a lot of man-hours. Conclusions: On the basis of tests results, this method cannot be considered as effective and alternative to the sieving analysis. The reason could be some discrepancies of the diameter of the sieve and the apparent diameter - two different ways of determining granularity of dust in this two methods. However, this method allows improving the sieving analysis process and estimating the granularity of the pre-dust, choose the right set and bulk of dust

A Useful Synthesis of Diethyl 1-Substituted Vinylphosphonates

A variety of diethyl 1-substituted vinylphosphonates 8 has been conveniently synthesized by piperidine catalyzed decarboxylative condensation of 2-diethoxyphosphorylalkanoic acids and 2-diethoxyphosphorylalkenoic acids 7 with formaldehyde. The Knoevenagel-Doebner decarboxylative condensation of alkanoic acids bearing C-2 electron withdrawing substituents with aldehydes has long been recognized as a convenient route to various a,b-unsaturated compounds Herein, we wish to describe an alternative, convenient route to diethyl 1-substituted vinylphosphonates 8 by the decarboxylative condensation of 2-diethoxyphosphorylalkanoic acids and 2-diethoxphosphorylalkenoic acids 7 with formaldehyde

Crystal structure of 7-cyano-6,7-dimethyl-1-phenyl-1,3,6,7-tetrahydro-2,1-benzoxaphospole 1-oxide

The crystals (C16H18NO2P, Mr=287.30) are orthorhombic, space group Pbca with a=8.200(2), b=14.857(2), and c=24.396(5)Å, V=2972.1 Å3, Z=8, Dx=1.284 mg m-3, λ(Mo Kα)=0.71069 Å, μ=1.90 cm-1, F(000)=216, T=295K. Final R=0.044 for 1673 observed reflections collected on a diffractometer. Structure solved by direct methods. Cis-junction and double bond in the six-membered ring cause its almost ideal sofa conformation. The two neighboring methyl groups are cis, and cyano substituent is in an equatorial position. There is a short intramolecular H(o-phenyl)⋯O(endocyclic) contact of 2.53(3)Å and the phenyl ring is in a less favorable rotational orientation due to molecular packing. © 1989 Plenum Publishing Corporation

Atrial fibrillation in patients with Wolff-Parkinson-White syndrome: Role of pulmonary veins

AimWe aimed to characterize electrophysiological properties of pulmonary veins (PVs) in patients with Wolff-Parkinson-White (WPW) syndrome and atrial fibrillation (AF), and to compare them to those in patients with WPW without AF.Methods and resultsA total of 31 patients (mean age 40 ± 15 years, 23 males) with WPW were recruited: 16 patients with (AF group) and 15 without (controls) a history of AF. The basic electrophysiological (EPS) and echocardiographic data were not different between the 2 groups. Effective refractory periods (ERPs) of PVs were significantly shorter in the AF group compared to controls: left superior (LS) PV ERP 185±29 versus 230 ± 24 ms, P = 0.001; left inferior PV ERP 198 ± 25 versus 219 ± 26 ms, P = 0.04; right superior (RS) PV ERP 207 ± 25 versus 236 ± 19 ms, P = 0.001; right inferior PV ERP 208 ± 30 versus 240 ± 19 ms, P = 0.003. Maximal veno-atrial conduction delay (i.e., the maximal prolongation of interval from stimulus delivered at PV ostia to proximal coronary sinus after extrastimulus compared to the basic drive cycle) was longer in the AF group when pacing from LSPV (69.3 ± 37.9 vs 32.6 ± 16.1 ms, P = 0.01) and RSPV (74.1 ± 25.9 vs 50.2 ± 26.5 ms, P = 0.04). During EPS, AF was induced more often in the AF group (n = 7) compared to controls (n = 1; P = 0.04). Follow-up revealed that AF recurred in 3 patients in the AF group and none of the controls.ConclusionPatients with WPW syndrome and AF have shorter ERPs of PVs and greater maximal veno-atrial conduction delay compared to patients with WPW without AF. These findings suggest a potential role of PVs in the development of AF in patients with WPW.Paweł Derejko, Łukasz Jan Szumowski, Prashanthan Sanders, Wojciech Krupa, Robert Bodalski, Michał Orczykowski, Piotr Urbanek, Joanna Zakrzewska, Han S. Lim, Dennis H. Lau, Jacek Kusnierz and Franciszek Walcza

Clinical Validation and Comparison of Alternative Methods for Evaluation of Entrainment Mapping

The definitive version may be found at www.wiley.comIntroductionMeasuring the postpacing interval (PPI) and correcting for the tachycardia cycle length (TCL) is an important entrainment response (ER). However, it may be impossible to measure PPI due to electrical noise on the mapping catheter. To overcome this problem, 2 alternative methods for the assessment of ER have been proposed: N+1 difference (N+1 DIFF) and PPIR method. PPI-TCL difference (PPI-TCL) correlates very well with ER assessed by new methods, but the agreement with PPI-TCL was established only in relation to PPIR method. Moreover, it is not known which of these methods is superior in the assessment of ER.MethodsWe analyzed 155 episodes of ER in 21 patients with heterogeneous reentrant arrhythmias. ER was estimated by PPI-TCL and by both alternative methods. Agreement between methods was assessed by means of the Bland-Altman test, kappa coefficient (kappa), and correlation coefficient (r). Finally, a mathematical comparison of the alternative methods was performed.ResultsThe agreement between PPI-TCL and alternative methods was very good. For N+1 DIFF the mean difference was -1.86 +/- 7.31 ms; kappa = 0.9; r = 0.98; for PPIR method the mean difference was -1.46 +/- 7.65 ms; kappa = 0.92; r = 0.99. Agreement between both alternative methods was also very high: the mean difference of 0.5 +/- 6.6 ms; kappa = 0.89; r = 0.99. The analysis of the equations used for calculation of ER by these methods revealed that essentially they were mathematically equivalent.ConclusionEach of the alternative methods may be used for evaluation of ER when PPI-TCL cannot be assessed directly. Results obtained by both alternative methods are comparable.Pawel Derejko, Lukasz J. Szumowski, Prashanthan Sanders, Hany Dimitri, Pawel Kuklik, Andrzej Przybylski, Piotr Urbanek, Ewa Szufladowicz, Robert Bodalski, Frederic Sacher, Michel Haissaguerre and Franciszek Walcza

Ablation of severe drug-resistant tachyarrhythmia during pregnancy

AimsThe goal of this study was to describe mapping and ablation of severe arrhythmias during pregnancy, with minimum or no X-ray exposure. Treatment of tachyarrhythmia in pregnancy is a clinical problem. Pharmacotherapy entails a risk of adverse effects and is unsuccessful in some patients. Radiofrequency ablation has been performed rarely, because of fetal X-ray exposure and potential maternal and fetus complications. GROUP AND METHOD: Mapping and ablation was performed in 9 women (age 24-34 years) at 12-38th week of pregnancy. Three had permanent junctional reciprocating tachycardia, and 2 had incessant atrial tachycardia. Four of them had left ventricular ejection fraction ResultsThree women had an electroanatomic map and ablation done without X-ray exposure. The mean fluoroscopy time in the whole group was 42 +/- 37 seconds. The mean procedure time was 56 +/- 18 minutes. After the procedure, all women and fetuses were in good condition. After a mean period of 43 +/- 23 months follow up (FU), all patients were free of arrhythmia without complications related to ablation either in the mothers or children.ConclusionAblation can be performed safely with no or minimal radiation exposure during pregnancy. In the setting of malignant, drug-resistant arrhythmia, ablation may be considered a therapeutic option in selected cases.Lukasz Szumowski, Ewa Szufladowicz, Michał Orczykowski, Robert Bodalski, Paweł Derejko, Andrzej Przybylski, Piotr Urbanek, Mariusz Ku´Smierczyk, Edward Ko´Zluk, Frederic Sacher, Prashanthan Sanders, Joanna Dangel, Michel Haissaguerre, and Franciszek Walcza