In vitro fragmentation performance of a novel, pulsed Thulium solid-state laser compared to a Thulium fibre laser and standard Ho:YAG laser

The aim of this work was to compare the fragmentation efficiency of a novel, pulsed Thulium solid-state laser (p-Tm:YAG) to that of a chopped Thulium fibre laser (TFL) and a pulsed Holmium solid-state laser (Ho:YAG). During the fragmentation process, we used a silicone mould to fixate the hemispherical stone models under water in a jar filled with room-temperature water. Each laser device registered the total energy applied to the stone model to determine fragmentation efficiency. Our study examined laser settings with single pulse energies ranging from 0.6 to 6 J and pulse frequencies ranging from 5 to 15 Hz. Similar laser settings were applied to explicitly compare the fragmentation efficiency of all three devices. We experimented with additional laser settings to see which of the three devices would perform best. The fragmentation performance of the three laser devices differed statistically significantly (p < 0.05). The average total energy required to fragment the stone model was 345.96 J for Ho:YAG, 372.43 J for p-Tm:YAG and 483.90 J for TFL. To fragment the stone models, both Ho:YAG and p-Tm:YAG needed similar total energy (p = 0.97). TFL’s fragmentation efficiency is significantly lower than that of Ho:YAG and p-Tm:YAG. Furthermore, we found the novel p-Tm:YAG’s fragmentation efficiency to closely resemble that of Ho:YAG. The fragmentation efficiency is thought to be influenced by the pulse duration. TFL’s shortest possible pulse duration was considerably longer than that of Ho:YAG and p-Tm:YAG, resulting in Ho:YAG and p-Tm:YAG exhibiting better fragmenting efficiency.

Evaluating the Performance of 193 nm Ultraviolet Photodissociation for Tandem Mass Tag Labeled Peptides

Despite the successful application of tandem mass tags (TMT) for peptide quantitation, missing reporter ions in higher energy collisional dissociation (HCD) spectra remains a challenge for consistent quantitation, especially for peptides with labile post-translational modifications. Ultraviolet photodissociation (UVPD) is an alternative ion activation method shown to provide superior coverage for sequencing of peptides and intact proteins. Here, we optimized and evaluated 193 nm UVPD for the characterization of TMT-labeled model peptides, HeLa proteome, and N-glycopeptides from model proteins. UVPD yielded the same TMT reporter ions as HCD, at m/z 126–131. Additionally, UVPD produced a wide range of fragments that yielded more complete characterization of glycopeptides and less frequent missing TMT reporter ion channels, whereas HCD yielded a strong tradeoff between characterization and quantitation of TMT-labeled glycopeptides. However, the lower fragmentation efficiency of UVPD yielded fewer peptide identifications than HCD. Overall, 193 nm UVPD is a valuable tool that provides an alternative to HCD for the quantitation of large and highly modified peptides with labile PTMs. Continued development of instrumentation specific to UVPD will yield greater fragmentation efficiency and fulfil the potential of UVPD to be an all-in-one spectrum ion activation method for broad use in the field of proteomics.

Application of Split Desktop Image Analysis and Kuz-Ram Empirical Model for Evaluation of Blast Fragmentation Efficiency in a Typical Granite Quarry

Evaluation of fragmentation efficiency is an integral aspect of blasting operation. This study therefore assesses the efficiency of fragmentation size at Eminent granite quarry, Ibadan, Nigeria using Split Desktop software and Kuz-Ram empirical model. Five muckpiles of blasted rocks with the same blast design were analysed. The muckpile images were captured using smart high precision digital camera and uploaded into computer for Split Desktop analysis. The results of the fragment size distribution obtained from Kuz-Ram vary slightly with that of the Split Desktop but follow similar trend. The average values of F80 and F90 from the Split Desktop image analysis were 90.96 cm and 98.24 cm respectively. The Kuz-Ram model values for F80 and F90 were 88.52 cm and 92.95 cm respectively. The results of the Split Desktop were compared to the results obtained from the Kuz-Ram experiential model. The findings showed that the results obtained from Kuz-Ram empirical model were in conformity with the results from the Split Desktop software based on empirical relationship. Hence, the model is good for preliminary evaluation of blast design. Keywords: Blasting, Particle Size Distribution, Split Desktop Software, Muckpile, Fragmentation Indicator

Development of a Laser-Photofragmentation Laser-Induced Fluorescence instrument for the detection of nitrous acid and hydroxyl radicals in the atmosphere

A new instrument for the measurement of atmospheric nitrous acid (HONO) and hydroxyl radicals (OH) has been developed using laser photofragmentation (LP) of HONO at 355 nm after expansion into a low-pressure cell, followed by resonant laser-induced fluorescence (LIF) of the resulting OH radical fragment at 308 nm similar to the fluorescence assay by gas expansion technique (FAGE). The LP/LIF instrument is calibrated by determining the photo-fragmentation efficiency of HONO. In this method, a known concentration of OH from the photo-dissociation of water vapor is titrated with nitric oxide to produce a known concentration of HONO. Measurement of the concentration of the OH radical fragment relative to the concentration of HONO provides a measurement of the photo-fragmentation efficiency. The LP/LIF instrument has demonstrated a 1σ detection limit of 9 ppt for a 10-min integration time. Ambient measurements of HONO and OH from a forested environment and an urban setting are presented along with indoor measurements to demonstrate the performance of the instrument.

Experimental determination of fragmentation efficiency for Plinian and Pelean eruptions of Mt. Pelée, Martinique

&lt;p&gt;Mt. Pel&amp;#233;e is a historically active volcano, situated on the island of Martinique (Lesser Antilles), that has shown a variety of explosive styles in the recent past, ranging from dome-forming (Pelean) to open-vent (Plinian) eruptions. &amp;#160;The 1902-1905 eruption is infamous for the pyroclastic density currents (PDCs) that destroyed the towns of St. Pierre and Morne Rouge, killing 30 000 residents. &amp;#160;Since the last eruption (dome-forming) in 1929-1932, Mt. Pel&amp;#233;e was quiet and considered dormant until recently. &amp;#160;In late 2020, the local Volcanological Observatory (OVSM) raised the alert level following a noticeable increase in seismicity, bringing into effect a reinforcement of monitoring resources. &amp;#160;As St. Pierre is long since re-established, along with several other towns along the volcano&amp;#8217;s flanks, it is of utmost importance to understand the possible range of eruptive activity to improve the preparedness strategies of local communities.&lt;/p&gt;&lt;p&gt;The precise controls on eruption dynamics vary across volcanic systems and cannot be constrained via direct observation. However, crucial inferences can be made based on petrophysical properties and mechanical behaviours of erupted materials.&amp;#160; For this study, we collected samples from PDC deposits of Mt. Pel&amp;#233;e, from the two historic Pelean (1902-1905, and 1929-1932) and three pre-Columbian Plinian eruptions (1300 CE P1, 280 CE P2, and 79 CE P3). We measured petrophysical properties (density, porosity, permeability) of cylindrical samples drilled from bomb-sized clasts and investigated their fragmentation behaviour via grain size and high-speed video analysis. These results are used in comparison with field data of grain-size distribution (GSD) of individual outcrops and calculated total GSD data. &amp;#160;We investigated the effects of transport-related sorting or fining.&lt;/p&gt;&lt;p&gt;The &amp;#8220;Pelean&amp;#8221; samples are found to be denser (32-47% open porosity) than the pumiceous &amp;#8220;Plinian&amp;#8221; samples (55-66% open porosity).&amp;#160; Moreover, these two classes are distinctly different in their crystallinity as samples underwent different ascent conditions. &amp;#160;In our experiments, distinct fragmentation behaviour and resulting GSDs are observed for samples from each eruption style, regardless of experimental pressure conditions (5-20 MPa). Our results show the paramount importance of open porosity on fragmentation efficiency in pumiceous samples, alongside a strong influence of crystallinity.&amp;#160; The fractal dimension of fragmentation calculated from weight fractions, independent of grain shape, shows clear differences in fragmentation efficiency as a function of sample properties and experimental starting conditions.&lt;/p&gt;&lt;p&gt;Our results suggest that (i) the variability in porosity and permeability is too low to cause the increased explosivity exhibited during the 1902 eruption compared to the 1929 event, (ii) open porosity has a major control on fragmentation efficiency in pumiceous samples, (iii) fragmentation efficiency can be effectively evaluated by calculating the fractal dimension of the cumulative weight fractions of experimental products.&lt;/p&gt;&lt;p&gt;The influence of crystallinity and pore textures on fragmentation efficiency must be further investigated to aid hazard model development for future eruptions of Mt. Pel&amp;#233;e. Future work will constrain these textural parameters of naturally and experimentally fragmented materials from Mt. Pel&amp;#233;e, to further elucidate the controls on eruptive dynamics at this hazardous volcano.&lt;/p&gt;

Pyroclast textures and fragmentation efficiency - constraining the range of eruptive dynamics of Mt. Pelée volcano, Martinique

&lt;p&gt;Mt. Pel&amp;#233;e is a historically active stratovolcano, situated on the island of Martinique in the French Caribbean.&amp;#160; It exhibits a variety of eruptive styles, from dome formation to highly violent explosivity.&amp;#160;&lt;/p&gt;&lt;p&gt;In 1902, a Pelean event destroyed the town of St. Pierre, killing more than 28,000 residents (Lacroix, 1904).&amp;#160; As this town is now re-established, along with several others along the volcano&amp;#8217;s flanks, it is of utmost importance to understand the range of eruptive activity possible such that preparedness of the local authorities and population can be improved.&lt;/p&gt;&lt;p&gt;There remains a gap in quantitative understanding of the energy required to fragment material to produce explosive eruptions, as this process is not directly observable.&amp;#160; Further, eruption records are incomplete (as at most volcanic islands) due to product loss to the ocean and intense tropical erosion.&amp;#160; Here, we constrain the energies of past eruptions by performing rapid decompression experiments and comparing the resulting grain-size distributions with primary deposits and dispersal in the field.&lt;/p&gt;&lt;p&gt;During a field campaign in March 2019, we collected ash and pumice blocks from five recent magmatic eruptions.&amp;#160; Two of these eruptions are historic (the Pelean episodes of 1902-1905, and 1929-1932), and three are prehistoric (the Plinian eruptions of 1300 CE P1, 280 CE P2, and 79 CE P3)(Carazzo et al. 2012).&amp;#160; We characterized ash (morphology), and constrained petrophysical (porosity, density, and permeability) and thermal properties of cylindrical samples. These cores (58-70% porosity) were subjected to rapid decompression in shock tube experiments to mimic explosive eruptions.&amp;#160; Fragmentation efficiency results from a combination of material properties and experimental conditions (temperature and overpressure). The particulate products were evaluated for their grain-size distribution in order to calculate the fractal dimension D&lt;sub&gt;f&lt;/sub&gt; and constrain eruptive conditions.&lt;/p&gt;&lt;p&gt;Our results provide new insights into the energy required for magma fragmentation at Mt. Pel&amp;#233;e and similar volcanoes. We hope to elucidate whether the 1902 eruption was catastrophic due to significant and measurable differences in eruption dynamics, or due to the flank topography and direction of the initial blast.&amp;#160;&lt;/p&gt;&lt;p&gt;&amp;#160;&lt;/p&gt;&lt;p&gt;References:&lt;/p&gt;&lt;p&gt;Carazzo, G., Tait, S., Kaminski, E., Gardner, E., (2012), The recent Plinian explosive activity of Mt. Pel&amp;#233;e volcano (Lesser Antilles): The P1 AD 1300 eruption, Bull. Volc., 74, 2187-2203, doi: 10.1007/s00445-012-0655-4&lt;/p&gt;&lt;p&gt;Lacroix, A. (1904) La Montagne Pel&amp;#233;e et ses &amp;#233;ruptions. Masson, Paris&lt;/p&gt;