Thermosalient materials - example of N'-2-propylidene-4-hydoxybenzohydrazide

Termosalientni (termoodskočni) materijali, obično još zvani ”skačući kristali”, obećavajući su materijali za pretvaranje toplinske (ili svjetlosne) energije u mehanički rad na nanoskali. Prilikom grijanja ili hlađenja, ovi materijali prolaze kroz nagle i oštre polimorfne fazne prijelaze gdje je sačuvan integritet jediničnih kristala. Tokom tog prijelaza, mijenja se oblik kristala, kao i veličina jedinične ćelije, i ta je promjena toliko velika da izaziva skakanje kristala na visine nekoliko puta veće od njih samih. Ovaj efekt obično se dogodi u nekoliko mikrosekundi. U literaturi je objavljeno da se N’-2-propiliden-4-hidroksibenzohidrazid ponaša slično kao skačući kristali. Utvrđeno je da se ovaj sustav pojavljuje u tri polimorfna oblika (I, II i III) iste prostorne grupe Pna21, s topotaktičkim (očuvan integritet jediničnih kristala) faznim prijelazima I u II i III u II (i obrnuto). Također je utvrđeno da prilikom ireverzibilnog faznog prijelaza iz I u II dolazi do snažne kompresije (oko 15%) duž polarne osi; jedinični kristali faze I raspadnu se na manje kristale faze II (skakanjem), a kod reverzibilnog prijelaza iz faze III u II dolazi do produljenja polarne osi (oko 14%) te nije opaženo skakanje. Naša mjerenja pokazuju malo drugačije ponašanje. Tokom ireverzibilnog faznog prijelaza iz I u II kristali su pokazali tipično ponašanje skačućih kristala te su skakali u nasumičnim smjerovima nekoliko centimetara daleko. Jedan dio kristala raspao se na manje, ali veliki broj kristala ostao je očuvan. Također, tokom reverzibilnog faznog prijelaza II u III (i obrnuto), dolazilo je do skakanja kristala, iako slabijeg nego kod prijelaza I u II. To je u suprotnosti sa dosadašnjim rezultatima, zbog čega je potrebno novo objašnjenje termosalientnog efekta kod ovog spoja.Thermosalient materials, or colloquially commonly called “jumping crystals”, are promising materials for conversion of thermal (or light) energy into mechanical work on the nanoscale. These materials, when heated or cooled, undergo a sudden and sharp polymorphic single crystal to single crystal phase transition. During this transition the crystals experience a change in their shape, as well as in the size of the unit-cell, and this change is so large that it causes them to jump up to a height that is several times bigger than their size. This phenomenon usually happens in several microseconds. It was reported that N’-2-propylidene-4-hydroxybenzohydrazide behaved similarly as the jumping crystals. It was found that this system exhibited three polymorphic modifications (I, II and III), all having the same polar space group Pna21, with the phase transitions I to II and III to II reported as topotactic (single crystal to single crystal). It was also reported that during the irreversible phase transition from I to II, the periodicity along the polar axis underwent a strong compression (approximately 15%); single crystals of the phase I were violently disintegrated into single crystal fragments of the phase II (with jumping), while in the reversible phase transition III to II the periodicity along the polar axis expanded (approximately 14%) and no movement of crystals was observed. Our measurements showed a somewhat different behaviour. During the irreversible phase transition from I to II some of the crystals did indeed disintegrate into smaller fragments, but a large number remained intact and showed a typical jumping crystal behaviour – jumping all around over large distances (several cm). This is typical for other thermosalient materials. Also, during the reversible phase transition II to III (both ways), crystals exhibited the jumping behaviour, but somewhat weaker than during the phase transition I to II. This is in contrast to the statements reported previously and the new model for the thermosalient effect in this system has to be proposed

Diagnostics and application of pulsed cold atmospheric pressure plasma

Ova disertacija bavi se dijagnostikom atmosferskog plazmenog mlaza koji pripada širokoj grupi hladnih neravnotežnih plazmi. U tu svrhu razvijen je eksperimentalni uređaj za generaciju visokonaponskih DC pulseva koji uzrokuju paljenje izboja na repeticiji od nekoliko kiloherca. Slobodni plazmeni mlaz karakteriziran je posredstvom optičke emisijske spektroskopije i mjerenjem struje izboja. Laserskom apsorpcijskom spektroskopijom u optičkom rezonatoru istražen je utjecaj različitih meta na koncentraciju atoma helija u metastabilnom stanju. Razvijen je eksperimentalni postav koji omogućava proučavanje međudjelovanja laserski inducirane plazme i plazmenog mlaza. Istraženi su efekti predionizacije na paljenje laserski inducirane plazme, te su napravljena prostorno razlučiva emisijska mjerenja i mjerenja za različita vremena kašnjenja između laserskog i naponskog pulsa. Predložena je nova eksperimentalna tehnika za dijagnostiku plazmenog mlaza, ali i ostalih tipova hladne plazme. Napravljena su emisijska mjerenja za vrijeme kontakta plazmenog mlaza i vode, te je istražen utjecaj plazmenog mlaza na pH vrijednost tretirane vode.This dissertation deals with diagnostics of atmospheric pressure plasma jet which belongs to a group of cold nonequilibrium plasmas. To that purpose, an experimental device has been developed for the generation of high voltage DC pulses used for repetitive (kHz) discharge ignition. Free plasma jet was characterised by means of optical emission spectroscopy (OES) and electrical measurements. Influence of different targets on helium metastable concentrations was investigated by means of cavity ring-down spectroscopy. Experimental setup that enables study of laser induced plasma interacting with the plasma jet was developed. Effects of preionisation on the ignition of laser induced plasma were investigated, as were effects of spatial coupling and synchronisation of laser and high voltage pulse by means of OES and absorbed energy measurements. A new experimental technique was proposed for the diagnostics of plasma jet and other types of cold plasma. OES measurements were performed during the interaction of the plasma jet with the water target and the pH value of the plasma treated water was measured for different treatment parameters

Diagnostics and application of pulsed cold atmospheric pressure plasma

Ova disertacija bavi se dijagnostikom atmosferskog plazmenog mlaza koji pripada širokoj grupi hladnih neravnotežnih plazmi. U tu svrhu razvijen je eksperimentalni uređaj za generaciju visokonaponskih DC pulseva koji uzrokuju paljenje izboja na repeticiji od nekoliko kiloherca. Slobodni plazmeni mlaz karakteriziran je posredstvom optičke emisijske spektroskopije i mjerenjem struje izboja. Laserskom apsorpcijskom spektroskopijom u optičkom rezonatoru istražen je utjecaj različitih meta na koncentraciju atoma helija u metastabilnom stanju. Razvijen je eksperimentalni postav koji omogućava proučavanje međudjelovanja laserski inducirane plazme i plazmenog mlaza. Istraženi su efekti predionizacije na paljenje laserski inducirane plazme, te su napravljena prostorno razlučiva emisijska mjerenja i mjerenja za različita vremena kašnjenja između laserskog i naponskog pulsa. Predložena je nova eksperimentalna tehnika za dijagnostiku plazmenog mlaza, ali i ostalih tipova hladne plazme. Napravljena su emisijska mjerenja za vrijeme kontakta plazmenog mlaza i vode, te je istražen utjecaj plazmenog mlaza na pH vrijednost tretirane vode.This dissertation deals with diagnostics of atmospheric pressure plasma jet which belongs to a group of cold nonequilibrium plasmas. To that purpose, an experimental device has been developed for the generation of high voltage DC pulses used for repetitive (kHz) discharge ignition. Free plasma jet was characterised by means of optical emission spectroscopy (OES) and electrical measurements. Influence of different targets on helium metastable concentrations was investigated by means of cavity ring-down spectroscopy. Experimental setup that enables study of laser induced plasma interacting with the plasma jet was developed. Effects of preionisation on the ignition of laser induced plasma were investigated, as were effects of spatial coupling and synchronisation of laser and high voltage pulse by means of OES and absorbed energy measurements. A new experimental technique was proposed for the diagnostics of plasma jet and other types of cold plasma. OES measurements were performed during the interaction of the plasma jet with the water target and the pH value of the plasma treated water was measured for different treatment parameters

Diagnostics and application of pulsed cold atmospheric pressure plasma

Ova disertacija bavi se dijagnostikom atmosferskog plazmenog mlaza koji pripada širokoj grupi hladnih neravnotežnih plazmi. U tu svrhu razvijen je eksperimentalni uređaj za generaciju visokonaponskih DC pulseva koji uzrokuju paljenje izboja na repeticiji od nekoliko kiloherca. Slobodni plazmeni mlaz karakteriziran je posredstvom optičke emisijske spektroskopije i mjerenjem struje izboja. Laserskom apsorpcijskom spektroskopijom u optičkom rezonatoru istražen je utjecaj različitih meta na koncentraciju atoma helija u metastabilnom stanju. Razvijen je eksperimentalni postav koji omogućava proučavanje međudjelovanja laserski inducirane plazme i plazmenog mlaza. Istraženi su efekti predionizacije na paljenje laserski inducirane plazme, te su napravljena prostorno razlučiva emisijska mjerenja i mjerenja za različita vremena kašnjenja između laserskog i naponskog pulsa. Predložena je nova eksperimentalna tehnika za dijagnostiku plazmenog mlaza, ali i ostalih tipova hladne plazme. Napravljena su emisijska mjerenja za vrijeme kontakta plazmenog mlaza i vode, te je istražen utjecaj plazmenog mlaza na pH vrijednost tretirane vode.This dissertation deals with diagnostics of atmospheric pressure plasma jet which belongs to a group of cold nonequilibrium plasmas. To that purpose, an experimental device has been developed for the generation of high voltage DC pulses used for repetitive (kHz) discharge ignition. Free plasma jet was characterised by means of optical emission spectroscopy (OES) and electrical measurements. Influence of different targets on helium metastable concentrations was investigated by means of cavity ring-down spectroscopy. Experimental setup that enables study of laser induced plasma interacting with the plasma jet was developed. Effects of preionisation on the ignition of laser induced plasma were investigated, as were effects of spatial coupling and synchronisation of laser and high voltage pulse by means of OES and absorbed energy measurements. A new experimental technique was proposed for the diagnostics of plasma jet and other types of cold plasma. OES measurements were performed during the interaction of the plasma jet with the water target and the pH value of the plasma treated water was measured for different treatment parameters

Tuning the composition of plasma-activated water by a surface-wave microwave discharge and a kHz plasma jet

An atmospheric pressure surface-wave microwave discharge and a kHz plasma jet are used to activate purified water. It is shown, that by varying the treatment distance and the initial Ar/N2/O2 mixture composition of the surface-wave microwave discharge the concentration ratio of NO−3 and H2O2 radicals created in the plasma activated water (PAW) can be varied over three orders of magnitude, which can be preserved during months of storage at room temperature. At the same time, with the 5 min treatment of the 32 ml water the absolute radical concentrations are varied in the range of 0.5–85 mg l−1 for H2O2, 20–180 mg l−1 for NO−3 and 0.5–14 mg l−1 for NO−2 . In the case of the N2 kHz plasma jet this concentration ratio can be tuned within one order of magnitude by varying the treatment distance. By treating different volumes very similar concentration ratios are obtained, which evolve differently during storage, as the ageing dynamics is determined by the absolute concentration of radicals. In general, the radical most affected by ageing is NO−2 , whose recombination is found to be determined by the H2O2 radical. In order to control the H2O2 concentration and thus the NO−2 radicals recombination, the application of a Fenton type reaction is suggested, which is implied by inserting a copper surface into PAW during or after plasma treatment

Chemical Evaluation, Antioxidant, Antiproliferative, Anti-Inflammatory and Antibacterial Activities of Organic Extract and Semi-Purified Fractions of the Adriatic Sea Fan, Eunicella cavolini

Due to sedentary lifestyle and harsh environmental conditions, gorgonian coral extracts are recognized as a rich source of novel compounds with various biological activities, of interest to the pharmaceutical and cosmetic industries. The presented study aimed to perform chemical screening of organic extracts and semi-purified fractions obtained from the common Adriatic gorgonian, sea fan, Eunicella cavolini (Koch, 1887) and explore its abilities to exert different biological effects in vitro. Qualitative chemical evaluation revealed the presence of several classes of secondary metabolites extended with mass spectrometry analysis and tentative dereplication by using Global Natural Product Social Molecular Networking online platform (GNPS). Furthermore, fractions F4 and F3 showed the highest phenolic (3.28 ± 0.04 mg GAE/g sample) and carotene (23.11 ± 2.48 mg β-CA/g sample) content, respectively. The fraction F3 inhibited 50% of DPPH (2, 2-diphenyl-1-picryl- hydrazyl-hydrate) and ABTS (2, 2′-azino-bis (3- ethylbenzthiazolin-6-yl) sulfonic acid) radicals at the concentrations of 767.09 ± 11.57 and 157.16 ± 10.83 µg/mL, respectively. The highest anti-inflammatory potential was exhibited by F2 (IC50 = 198.70 ± 28.77 µg/mL) regarding the inhibition of albumin denaturation and F1 (IC50 = 254.49 ± 49.17 µg/mL) in terms of soybean lipoxygenase inhibition. In addition, the most pronounced antiproliferative effects were observed for all samples (IC50 ranging from 0.82 ± 0.14–231.18 ± 46.13 µg/mL) against several carcinoma cell lines, but also towards non-transformed human fibroblasts pointing to a generally cytotoxic effect. In addition, the antibacterial activity was tested by broth microdilution assay against three human pathogenic bacteria: Escherichia coli, Pseudomonas aeruginosa, and Staphylococcus aureus. The latter was the most affected by fractions F2 and F3. Finally, further purification, isolation and characterization of pure compounds from the most active fractions are under investigation

Endoparaziti u divljih mačaka u Hrvatskoj

Reports on the parasitic fauna of wildcats (Felis silvestris silvestris) are rare and often based on a small sample size, therefore the goal of this research was to investigate the prevalence of endoparasites in wildcats in Croatia. Necropsy was conducted on 34 adult wildcats killed in traffic or provided by hunters following regular hunting operations. All animals tested negative for rabies. The contents of the stomach and intestine were examined under a microscope. Feces from the rectum were analyzed using flotation with a saturated ZnSO4 solution, while the diaphragm was examined using artificial digestion. Direct immunofluorescence was used for the first time to detect Giardia sp. cysts in wildcats. All animals were infected with at least one species of parasites, while the most diverse infestation included six different species of parasites in a single animal. The following parasite species were found (% of prevalence of adult parasites and their developmental stages in all analyzed samples): Taenia taeniaeformis (55.9%), Capillaria sp. (50%), Toxocara cati (50%), Isospora sp. (29.4%), Strongyloides sp. (23.5%), Giardia sp. (17.6%), Ancylostoma tubaeformae (14.7%), Physaloptera sp. (11.8%), Hymenolepididae (8.8%), Alaria alata (5.9%), Aelurostrongylus abstrusus (5.9%), Toxascaris leonina (5.9%), Trichinella sp. (5.9%), Mesocestoides lineatus (5.9%), Anoplocephalidae (2.9%), Dipylidium caninum (2.9%), Trichuris sp. (2.9%), Isospora felis (2.9%), Eimeria sp. (2.9%) and Sarcocystis sp. (2.9%). Among those, Eimeria sp., Trichuris sp. eggs, anoplocephalid and hymenolepidid type eggs are spurious parasites, coming from ingested prey. Four of the identified species have never been previously reported in wildcats - Giardia sp., Strongyloides sp., Sarcocystis sp. and Dipylidium caninum.Znanstveni radovi o parazitima divljih mačaka (Felis silvestris silvestris) rijetki su i najčešće rađeni na malom broju uzoraka te je stoga naš cilj bio istražiti učestalost endoparazita divljih mačaka u Hrvatskoj. Pregledali smo lešine 34 divlje mačke, stradale u prometu ili u sklopu provedbe lovnogospodarskih osnova. Sve su životinje bile negativne na bjesnoću. Sadržaj želudca i crijeva pregledali smo pod mikroskopom. Izmet iz debelog crijeva pregledan je metodom flotacije pomoću zasićene otopine ZnSO4, dok je dijafragma pregledana pomoću umjetne probave. Upotrijebili smo izravnu imunofluorescenciju za utvrđivanje cista Giardia sp., što je prvo takvo istraživanje kod divljih mačaka. Sve pregledane životinje bile su invadirane barem jednom vrstom parazita, dok je najraznolikija invazija uključivala šest različitih vrsta parazita utvrđenih kod jedne životinje. Sljedeće su vrste parazita identificirane (% prevalencije odraslih parazita i razvojnih stadija u svim analiziranim uzorcima): Taenia taeniaeformis (55,9 %), Capillaria sp. (50 %), Toxocara cati (50 %), Isospora sp. (29,4 %), Strongyloides sp. (23,5 %), Giardia sp. (17,6 %), Ancylostoma tubaeformae (14,7 %), Physaloptera sp. (11,8 %), Hymenolepididae (8,8 %), Alaria alata (5,9 %), Aelurostrongylus abstrusus (5,9 %), Toxascaris leonina (5,9 %), Trichinella sp. (5,9 %), Mesocestoides lineatus (5,9 %), Anoplocephalidae (2,9 %), Dipylidium caninum (2,9 %), Trichuris sp. (2,9 %), Isospora felis (2,9 %), Eimeria sp. (2,9 %) i Sarcocystis sp. (2,9 %). Među njima, Eimeria sp., Trichuris sp., jaja anoplocefalida i himenolepidida su pseudoparaziti, koji potječu od plijena. Četiri roda koje smo identificirali do sada nisu nikada opisani kod divljih mačaka - Giardia sp., Strongyloides sp., Sarcocystis sp. i Dipylidium caninum

The Awareness of the Students about Testicular Tumors

Cilj: Ispitati upućenost studenata o tumorima testisa, poznavanju samopregleda i motiviranosti da steknu dodatna znanja o ovoj bolesti. Ispitanici i metode: U istraživanje je bilo uključeno 116 studenata Sveučilišta u Rijeci. Prvu grupu (42 studenta) sačinjavali su studenti prve godine Odjela za informatiku, drugu su grupu sačinjavala 44 studenata druge godine Odjela za informatiku, a 30 mladića ostale studentske populacije sačinjavalo je treću grupu. Za istraživanje se koristio anonimni anketni upitnik s 18 pitanja. Rezultati: Medijan dobi u prvoj i trećoj grupi bio je 19 godina, a u drugoj grupi 20 godina. Najveći broj studenata dolazio je iz Primorsko-goranske županije. O tumorima testisa čulo je 71,4 % studenata iz prve grupe, 93,2 % studenata iz druge grupe i 90 % studenata iz treće grupe. Najvažniji izvor informacija za sve tri grupe su Internet i televizija. Samopregled testisa učinilo je 57,8 % ispitanika, a samo njih 45,7 % zna kako ga ispravno učiniti. Zaključci: Studenti su putem Interneta i televizije upoznati s tumorima testisa i imaju želju da budu još bolje informirani. Samopregled testisa, kojim se ova bolest može otkriti, provodi samo oko 50 % studenata, a manje od 50 % ih zna kako ga i učiniti, što je nezadovoljavajuće. Podatci dobiveni našom studijom pokazuju kako je neophodno provesti edukaciju studenata o ovom zdravstvenom problemu.Aim: The aim of the study was to examine students’ awareness of testicular tumors, their knowledge of self-examination, and motivation to learn more about the disease. Subjects and Methods: The survey was conducted among 116 students of the University of Rijeka. The first group (42 students) consisted of first year students of the Department of Informatics, the second group consisted of 44 students of the second year of the Department of Informatics and the third group consisted of 30 young men of other student population. The survey used an anonymous survey questionnaire with 18 questions. Results: The median age of the participants in the first and third group was 19 years and 20 years in the second group. The largest number of students came from Primorje-Gorski Kotar County. The information about testicular tumor was known in 71.4% of students in the first group, 93.2% of students in the second group and 90% of students in the third group. The most important source of information for all three groups is the Internet and television. The testicular self-examination was done by 57.8% of the participants, and only 45.7% knew how to do it properly. Conclusions: Students are familiar with testicular tumors via the Internet and television and are eager to be better informed. Testicular self-examination, the method that can detect this disease, is conducted by only 50% of students, and less than 50% know how to do it, which is unsatisfactory. The data of our study show that it is necessary to educate students about this health problem

Reversible thermosalient effect of N′-2-propylidene-4-hydroxybenzohydrazide accompanied by an immense negative compressibility: Structural and theoretical arguments aiming toward the elucidation of jumping phenomenon

The temperature-induced reversible phase transition of N′-2-propylidene-4-hydroxybenzohydrazide from the polymorphic Form II to Form III, and vice versa, is accompanied by the dramatic change of the macroscopic dimensions of the crystal which resulted in the pronounced mechanical motion (jumping) during the phase transition. Prior to the phase transition, the extremely large uniaxial negative thermal expansion along one crystal axis (b axis) was observed, together with the positive thermal expansions along the other two crystal axes. Form III of N′-2-propylidene-4-hydroxybenzohydrazide exhibits the thermal expansion α = 360 × 10 K, which is the largest value ever noticed in any organic or metal-organic crystal. From the structural point of view, a thermosalient effect is escorted by the springlike behavior of the zig-zag molecular assemblies along the c axis. First-principles electronic structure calculations show that negative thermal expansion arises from the elastic properties of the crystal which show uniaxial negative compressibilities, NLC. Form III exhibits the negative compressibility along the 001 direction β = -28 TPa, which is 1 order of magnitude larger than that of any organic compound and, in fact, is comparable to compressibilities of molecular frameworks showing the most pronounced NLC behavior. Elastic properties are also the reason for the reversibility of Form II to Form III transition in contrast to the irreversible Form I to Form II transition. Low energy springlike phonons are easily thermally excited and can assist in the overcoming of the energy barrier between the two phases that precedes thermosalient transition.This work was supported by the Croatian Science Foundation project IP-2014-09-7506.Peer Reviewe