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venerdì 3 luglio 2020

# gst: contactless manipulation of droplets levitating in an acoustic wave

<< A unique, versatile, and material-independent approach to manipulate contactlessly and merge two chemically distinct droplets suspended in an acoustic levitator is reported. Large-amplitude axial oscillations are induced in the top droplet by low-frequency amplitude modulation of the ultrasonic carrier wave, which causes the top sample to merge with the sample in the pressure minimum below. The levitator is enclosed within a pressure-compatible process chamber to enable control of the environmental conditions. The merging technique permits precise control of the substances affecting the chemical reactions, the sample temperature, the volumes of the liquid reactants down to the picoliter range, and the mixing locations in space and time. >>

Stephen J. Brotton, Ralf I. Kaiser. 
Controlled Chemistry via Contactless Manipulation and Merging of Droplets in an Acoustic Levitator. Anal. Chem. 2020, 92, 12, 8371–8377. doi: 10.1021/ acs.analchem.0c00929. Jun 1, 2020. 


Levitating droplets allow scientists to perform 'touchless' chemical reactions.  American Chemical Society. Jun 24, 2020.



mercoledì 1 luglio 2020

# life: apropos of transitional blennies

<< Research on blennies, a family of fish that have repeatedly left the sea for land, suggests that being a 'jack of all trades' allows species to make the dramatic transition onto land but adapting into a 'master of one' allows them to stay there. >>

<< a flexible diet and behavior were likely to be instrumental in the transition to land. However, once out of the water, restrictions on the type of food available triggered major evolutionary changes, particularly to their teeth, as land dwelling blennies have become specialists in scraping algae and detritus from rocks. >>

<< having a broad diet or being behaviorally flexible can help you move into a new habitat. But once there, this flexibility becomes eroded by natural selection. This presumably means those highly specialized species are less likely to be able to make further transitions, or cope with abrupt environment changes in their existing habitat. >> Terry Ord.

How fish got onto land, and stayed there. British Ecological Society. Jun 17, 2020.  


Terry J. Ord, Peter J. Hundt. Crossing extreme habitat boundaries: Jack‐of‐all‐trades facilitates invasion but is eroded by adaptation to a master‐of‐one. Funct Ecol. doi: 10.1111/ 1365-2435.13600. Jun 16, 2020.


Also

The multifactorial relationship system evolved in Blenny. FonT. Jun 2, 2017.



martedì 30 giugno 2020

# gst: elastic instabilities, a morphing model to quickly trap anything (in 100msec), the Venus flytrap (Dionaea muscipula)

<< The Venus flytrap (Dionaea muscipula) takes only 100 milliseconds to trap its prey. Once their leaves, which have been transformed into snap traps, have closed, insects can no longer escape. >>

<< the trap of the carnivorous plant is under mechanical prestress. In addition, its three tissue layers of each lobe have to deform according to a special pattern. >>

<< In order to close correctly, the traps also had to consist of three layers of tissue: an inner which constricts, an outer which expands, and a neutral middle layer. >>

Albert Ludwigs. Biomechanical analyses and computer simulations reveal the Venus flytrap snapping mechanisms. University of Freiburg. Jun 23, 2020.


Renate Sachse, Anna Westermeier, et al. Snapping mechanics of the Venus flytrap (Dionaea muscipula). PNAS. doi: 10.1073/ pnas.2002707117. Jun 22, 2020. 


Also

Dionaea muscipula, with precision. FonT. Feb 2, 2016. 




lunedì 29 giugno 2020

# gst: self-assembly in complex patterns during the evaporation of a sessile droplet

<< When a sessile droplet containing a solute in a volatile solvent evaporates, flow in the droplet can transport and assemble solute particles into complex patterns. >>

Bryan A. Nerger, P.-T. Brun, Celeste M. Nelson. Marangoni flows drive the alignment of fibrillar cell-laden hydrogels. Science Advances. Vol. 6, no. 24, eaaz7748. doi: 10.1126/ sciadv.aaz7748. Jun 12, 2020.


Thamarasee Jeewandara. Marangoni flows drive the alignment of fibrillar cell-laden hydrogels. Phys.org. Jun 25, 2020


Also

keyword 'Marangoni effect'





giovedì 25 giugno 2020

# life: a paradigm shift; extinction vs. evanescence, relict species, ...

<< The first "complete" paradigm of extinction was proposed as "the multigenerational, attritional loss of reproductive fitness," for which MALF is a suitable acronym. A "complete" paradigm must encompass cause, effect, and a mechanism. The primary goal of this study is to verify the new paradigm. (AA) cite four independent tests of the paradigm employing observational, experimental, and wholly theoretical techniques, >>

<< "extinction" presents certain problems with adjectival and gerund forms. (AA) do not refer to a process of "extinctioning" or "extincting" and there is no disciplinary field named "extinctionary" biology, ecology, or genetics. There are several possible verbs for extinction that treat the population or species as agent. These include "devolve," "senesce," "die off," "terminate," and "disappear," among others. However, all of these are in common use with connotations that would distract from (they) proposed meaning. "Devolve" is common in antievolutionist literature. "Senesce" is usually applied only to individuals. "Die off" does not have a single-word noun form. "Terminate" used intransitively comes close to our proposed meaning, but the popularity of the Arnold Schwarzenegger film Terminator will suggest the transitive form to most people. "Disappear" suggests something that is merely out of sight, not necessarily extinct. Instead of these common words, (they) propose using a verb with no distracting connotations. (AA) take our cue from Jefferson’s concern over extinction. Jefferson (1799:256) uses the term "evanish," or in its modern form, "vanish." The adjectival form "vanished" is usable but the noun form sounds a bit awkward: "vanishment." However, Jefferson’s "evanish" calls attention to the Latin root, e + vanescere = to pass away. "Evanesce" has an elegant noun form, "evanescence," and several adjectival forms covering a range of states: "evanesced" denoting the completed action, "evanescing" denoting an action in process, and "evanescent" denoting action in process or in potential. In physics, the adjective "evanescent" is used to designate an electromagnetic field that does not propagate waves beyond the vicinity of the source of the field. Physics and biology are sufficiently distinct that (AA) proposed usage would not create confusion. "Evanescence" does not imply an external agent performing the action and fits the understanding of extinction as a process without adding confusing connotations. This process may be a precursor or complement to evolution, but not necessarily so. >>

Delbert Wiens, Timothy Sweet, Thomas Worsley. Validating the New Paradigm for Extinction: Overcoming 200 Years of Historical Neglect, Philosophical Misconception, and Inadequate Language. The Quarterly Review of Biology. Vol. 95, Issue 2, Pages 109-124. doi: 10.1086/709086. Jun 2020.


Goodbye 'extinction,' hello 'evanescence'? Validating a new paradigm. University of Chicago. Jun 18, 2020. 



lunedì 22 giugno 2020

# bots: tiny machinery, nanobots (molecule-sized bots) from 1k to millions swarming together to perform tasks

<< Multi-disciplinary research has led to the innovative fabrication of molecule-sized robots. Scientists are now advancing their efforts to make these robots interact and work together in the millions. >>

AA << have made molecular robots with three key components: microtubules, single-stranded DNA, and a light-sensing chemical compound. The microtubules act as the molecular robot's motor, converting chemical energy into mechanical work. The DNA strands act as the information processor due to its incredible ability to store data and perform multiple functions simultaneously. The chemical compound, azobenzene derivative, is able to sense light, acting as the molecular robot's on/off switch. (..) (They) have successfully controlled the shape of those swarms by tuning the length and rigidity of the microtubules. Relatively stiff robots swarm in uni-directional, linear bundles, while more flexible ones form rotating, ring-shaped swarms.>>

<< A continuing challenge, though, is making separate groups of robots swarm at the same time, but in different patterns. This is needed to perform multiple tasks simultaneously. >>

Scientists working to make molecule-sized robots swarm together to perform tasks. National Institute for Materials Science. Jun 18, 2020.


Arif Md. Rashedul Kabir, Daisuke Inoue,  Akira Kakugo. Molecular swarm robots: recent progress and future challenges.  Science and Technology of Advanced Materials. 21:1, 323-332. doi: 10.1080/ 14686996.2020.1761761. Jun 16, 2020. 


Also

keyword 'bot' in FonT





sabato 20 giugno 2020

# life: unaware racisms

<< racism is about action in everyday life, not just words or hashtags at a time of uprising. We can be careful about what we say – language is conscious and controllable. But it is perfectly possible to hold deep-seated racist views, sometimes subconsciously, and simultaneously announce you are definitely not racist. >>

Geoff Beattie. Black Lives Matter: you may be a vocal supporter and still hold racist views. Jun 17, 2020


Also

keyword "CTZ" in FonT