103,461 research outputs found
Glossoscolex (Glososscolex) maschio Feijoo & Brown 2018, sp. nov.
No full textGlossoscolex (Glososscolex) maschio sp. nov. (Figure 2) Etymology. Named in honor of Wilson Maschio & Wagner Maschio, father and son, for their contributions to the study of earthworms in southern Brazil. Noun in apposition. Holotype. COFM BRPR0433, one clitellate specimen found crawling on the surface of the road after rainfall next to mixed ombrophylous forest (Araucaria forest) at Embrapa Florestas, Colombo municipality, state of Paraná, Brazil; 25°18'56.88"S, 49°9'31.21"W, 950 masl, 18-04-2012, Wagner Maschio, coll. Paratype. COFM BRPR0191, 1 adult, same location as holotype, 10-02-2011, Wagner Maschio, coll. Other material examined. COFM BRPR0190, 1 adult, same location as holotype, 8-10-2008, Wilson Maschio, coll. Description. Epiendogeic species with cylindrical body and brown color dorsally and light brown ventrally and dark brown in the clitellum (color Nos. 701, 698 and 694, respectively according to Seguy, 1936). Holotype: length of preserved holotype 250.2 mm, diameter 7.99 mm in the preclitellar region, 9.03 mm in the clitellum, and 6.27 mm in the postclitellar region. Number of segments: 343. Paratype: length 177.1 mm long and widths of 6.39 mm (segment 10), 7.38 mm (segment 20) and 4.78 mm (segment 38). Number of segments: 345. Prolobic prostomium with first segment invaginated. Eight rows of closely paired setae a, b, c, d, visible from segment 12 on. The distance between the setae in segment 40 is aa:ab:bc:cd:dd = 12.2:1:4.7:0.4:24. The first 12 segments have transverse grooves; from segment five on, secondary annulations are present. The saddle-shaped clitellum lies in segments 15–24 (=10), with tubercula pubertatis in segments 19– 2/3 20, 21 (=1 2/3, 2 1/2) (Fig. 2A). The male pores are located in segment 18/19 and female pores in segment 14. The nephropores are above the line of b setae. Spermathecal pores absent. Internal anatomy. Septa of segments 6/7–10/11 are thick, conical and interpenetrated. Large, strong heartshaped gizzard in segment 6. One pair elongated calciferous glands 4.1 mm long in segment 12, with composite tubular structure (Kompositenschlauchtaschen), and lumen greatly irrigated with blood vessels that completely fill the interior spaces of the gland. Oesophagus-intestine transition in segment 14 and typhlosole beginning in segment 15, with an S-shaped folded dorsal lamina that occupies 2/3 of the intestinal lumen. The first part of the intestine, from the transition between the oesophagus up to segment 43 was empty and thereafter abundant quantities or organic matter and small wood pieces were observed in all three dissected specimens. Intestinal caeca absent. Five pairs of lateral-oesphageal hearts in segments 7–11. One pair of preseptal holonephridia per segment. Testes and funnels in single midventral subesophageal sac in segment 11. Ovaries and ovarian funnels in segment 13. One pair of whitish lobulated large seminal vesicles restricted to segment 12. Spermathecae absent. Male sexual system metandric, with vas deferens beginning in segment 11, extending backwards along c–d setae line, penetrating the copulatory chambers and exiting at the male pore in segment 18/19. Cylindrical-shaped copulatory chamber in segments 18–19 (Fig. 2B). Remarks. The subgenus Glossoscolex (Glossoscolex) has 48 species/subspecies, but only 16 of them have male pores in segments 18 and 19 or 19, and are therefore part of the giganteus group according to Righi & Lobo (1979) (see discussion), which now includes G. maschio sp. nov. However, of these only eight species have clitellum ranging from 15–23 (G. umijae Righi & Lobo, 1979; G. (G.) paulistus Michaelsen, 1925; G. (G.) facchini Righi, 1971; G. (G.) gordurensis Michaelsen, 1918; G. (G.) fasold Michaelsen, 1918; G. (G.) montagneri Righi, 1972 and G. (G.) mrazi Černosvitov, 1934), but only one of these has seminal vesicles restricted to 11 and 12 (G. paulistus). All other species have vesicles extending further back, from 13 (G. fasold), to 15 (G. mrazi, G. facchini) and beyond (other species). Although Righi (1978) states that seminal vesicle extension by itself is not a good enough character to define species differences, because it varies with maturation stage of the earthworm, all individuals evaluated were clearly adult, collected at different dates and had their seminal vesicles restricted to segment 12. Furthermore, when aided by other somatic characters such as clitellum position, size and shape of copulatory pouch and setal arrangements, it can be of use. The copulatory chamber of G. paulistus is large and reniform (kidney-shaped), occupying segments 17/18–23, while that of G. maschio sp. nov. is cylindrical and occupies only segments 18–19. Furthermore, seminal vesicles of G. maschio are short and restricted to segment 12, while those of G. paulistus are irregularly shaped and occupy segments 11 and 12. The setal arrangements of G. paulistus (21.8:1:5:0.8:23.8) is different from that of G. maschio (12.2:1:4.7:0.4:24). G. fasold, the only other species close enough to G. maschio by extension of its seminal vesicles is a very large earthworm (about 1 m long), with setal arrangements quite different from G. maschio (5:1:1.7:1:6.9), but for which we do not have exact details on copulatory chamber shape or placement. However, Michaelsen (1918) considered this species close to G. wiengreeni Michaelsen, 1897 and G. giganteus, both of which are quite different from G. maschio, particularly in their copulatory chamber placement (segments 18–22 and 18–20, respectively) and clitellum position (segments 15–24/25 and 15–24, respectively).Published as part of Feijoo, Alexander & Brown, George G., 2018, New species of Glossoscolex and Fimoscolex earthworms (Oligochaeta: Glossoscolecidae) from Embrapa Forestry, Paraná, Brazil, pp. 492-502 in Zootaxa 4496 (1) on pages 496-498, DOI: 10.11646/zootaxa.4496.1.38, http://zenodo.org/record/144699
A calorimetric study of a commercial monomer autopolymerization: an accident investigation.
No full textIn this work the analysis of an incident in transport of dangerous goods is proposed.
The objective of this study is to contribute to the determination of the causes that brought about the self-polymerization of commercial divinylbenzene (DVB 63%) contained in an isothermal container, in order to prevent this incident from happening in the future.
Time and conditions during transport/storage of monomers (in particular storage temperature) are very important factors that affect their aptitude of self-polymerization.
In particular one hypothesis has been investigated: that the quantity of oxygen in the tanker was insufficient to activate properly the inhibition mechanism. Consequently, the self-polymerization of DVB and the inhibition mechanism of 4-tert-Butylcatechol (TBC) have been studied as a function of temperature and monomer exposure to air with Differential Scanning Calorimetry and Adiabatic Calorimetry techniques
Screening Analysis for Hazard Assessment of Peroxides Decomposition
No full textIn this study the analysis of different kind of organic peroxides decomposition by screening calorimetry
is proposed. The aim is to analyze the kinetic and thermodynamic of the decomposition reactions and to
evaluate the consequences in particular when the process undergoes to thermal explosion and may be
the cause of incidents. Screening calorimetry data allow us to define the conditions and ranges of
temperature and pressure evolved during the reaction. In the experimental apparatus used (a screening
calorimeter), the experiments have been carried out safely even when there is a rapid and large increase
in temperature and pressure. Scanning and isothermal conditions has been investigated. An Early
Warning Detection System (EWDS) for thermal runaway based on the divergence criterion has also
been applied off-line to the experimental isothermal data, in order to evaluate the sensitivity of the
method applied to both temperature and pressure profiles. The results of the application of the EWDS
have been compared to the ones obtained by Hub and Jones criterion
Reaction Calorimetry and UV-Vis Spectrophotometry Integration aimed at Runaway Reaction Early Detection
No full textThe use of different calorimetric techniques for process design and scale up is well consolidated, allowing
the definition of the kinetic and thermodynamic of the process and the evaluation of several parameters
useful to optimization and process safety. During a calorimetric analysis temperature (or a temperature
difference) is measured; from experimental data it is for example possible to calculate the heat flow and
the heat evolved by the reaction and consequently the conversion and the reaction rate constant just if
kinetics of the reaction is known. To overcome these limitations and to obtain additional information about
the reaction, it is possible to couple to a calorimeter different type of sensors such as densitometers,
refractometers, electrochemical, chromatographic and spectrophotometric probes (Schwedt, 1997). Some
of these sensors are able to log data on line during the process and so to monitor the reaction at the same
time of the calorimetric analysis. For safety aims, it is important to choose a sensor whose time for the
analysis is comparable to the reaction time in order to have an accurate profile of the monitored parameter
during the reaction (Moritz, 1989).
In a previous study (Parisi, 2002; Ampelli et al. 2003) an Ultra Violet - Visible spectrophotometer was
integrated to a reaction calorimeter to analyse the kinetic of a specific reaction. In this work a similar UV -
Vis probe has been coupled to an isoperibolic reaction calorimeter in order to study the feasibility of the
application of an Early Warning Detection System (EDWS) to a spectrophotometric signal. The innovation
of this integration of techniques is the analysis of the spectrophotometric signals with a reactor stability
criterion based on divergence theory in order to check if this method of monitoring allows detecting
runaway reactions at an early stage of the process, when it is still possible to take protective measures.
The innovation of the integration between the calorimetric and the spectrophotometric techniques is the
application of an Early Warning Detection System based on divergence criterion to spectrophotometric
signals in order to check if this method of monitoring high reactive processes could lead to a greater
advance in the detection of the thermal explosion with respect to temperature monitoring.
The results are that EWDS does not give a good result in the detection of the onset when applied to
Absorbance signal: it is not possible to define a ΔVLIM, and the profile of ΔV does not show a peak when
adding catalyst. This makes the analysis not reliable and subject to false alarm. This monitoring cannot be
used for process safety purpose.
The application of the method to the Intensity signal gives different results. There is the detection of the
onset 1 second before the profile of Intensity starts to decrease and the noise is more smoothed than in
the previous case. The algorithm is able to detect the runaway start 59 seconds before the maximum of
temperature is developed (6 seconds before the application to temperature signal). This monitoring could
be used at the same time than temperature monitoring, in order to improve the efficiency of the system in
detecting runaway reaction decreasing the possibilities of false alarms. The method could be very useful if
applied to those processes in which the accumulation of a reaction intermediate, that develops no
temperature increase in the system, could lead to thermal explosion by starting a secondary reaction: in
this case the EWDS working on Intensity signal (that can be monitored on line, during the process) could
detect the runaway at a very early stage, when the temperature in the system could still be kept under
control by some protective measure activated after the alarm.
The integration of calorimetry and spectrophotometry gave good results: spectrophotometry is able to
supply useful data for process modelling and also for safety purpose. This methodology could be easily
implemented in a plant-scale reactor providing a valid process safety monitoring against runaway
reactions.
The divergence criterion account reasonably well for the thermal runaway in the considered reaction. An
advantage of the Strozzi and Zaldívar criterion over existing criteria is that it is possible to reconstruct,
using non-linear time series analysis techniques, the divergence of the system from a monitored signal
without the necessity to have a model for the process. Hence, all the results and conclusions obtained
from an off-line analysis may be extended and applied on-line to develop a general early warning detection
device, based on a robust criterion
CALORIMETRIC STUDY OF THE INHIBITION OF THE RUNAWAY REACTION DURING POLYMERIZATION PROCESSES
No full textTHERMAL-SHOCK RESISTANCE OF MATERIALS BASED ON CEO2-STABILIZED TETRAGONAL ZIRCONIA POLYCRYSTALS
No full textMaterials based on tetragonal zirconia polycrystals fully stabilized with CeO2 have been prepared starting from commercial powders. The mechanical properties of samples with different compositions were measured at room temperature and after quench tests. The effects of thermal treatments on the microstructure and crystal phases and their detrimental influence on strength, toughness and hardness were evaluated. Experiments demonstrated that residual porosity and higher amounts of ceria favourably influence the retention of material properties after thermal treatment
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