1,001 research outputs found
Scanning Electron Fractography of Body Centered Cubic (BCC) Metals
Scanning electron fractography is an inherent part of investigations of factors which determine the mechanical properties of materials and their failure. Transition bcc metals show the widest variety of fracture mechanisms under uniaxial tension.
Brittle fracture is affected by cleavage from various defects - stress concentrators.
In brittle-ductile transition, fracture starts by a tough mode but finishes by a brittle one - by cleavage. A fracture mechanism changes after the tough crack has reached some critical length. Mechanisms of subcritical growth are of cleavage with relaxation, inter-granular fracture and dimpled ones.
Dimples are observed in ductile fracture. Cleavage is absent. The dimples are nucleated as a result of both failure of particles and their interfaces and delamination of structure elements.
All varieties of observed fracture surface may be described as a result of actions of the following mechanisms - cleavage, cleavage with relaxation, pore coalescence, brittle intergranular or intercellular fracture.
Fractographical analysis allows one to obtain information not only about the fracture mechanisms but also such characteristics as: fracture toughness, brittle-ductile transition limits, structure transformations preceding fracture
Kinetics of Twinning and Dislocation Slip During Cyclic Deformation of ZK30 Magnesium Alloy
The present study clarifies the anisotropy of tension-compression behaviour during the cyclic deformation of ZK30 magnesium alloy. Some details of mechanical twinning and dislocation slip are studied by acoustic emission technique and direct video observations. Through the combination of these methods, the overall effect of deformation mechanisms is determined for each loading direction and their effect on the cyclic deformation is highlighted
A Hybrid N-body--Coagulation Code for Planet Formation
We describe a hybrid algorithm to calculate the formation of planets from an
initial ensemble of planetesimals. The algorithm uses a coagulation code to
treat the growth of planetesimals into oligarchs and explicit N-body
calculations to follow the evolution of oligarchs into planets. To validate the
N-body portion of the algorithm, we use a battery of tests in planetary
dynamics. Several complete calculations of terrestrial planet formation with
the hybrid code yield good agreement with previously published calculations.
These results demonstrate that the hybrid code provides an accurate treatment
of the evolution of planetesimals into planets.Comment: Astronomical Journal, accepted; 33 pages + 11 figure
The effect of excretory-secretory antigen of Trichinella spiralis muscle larvae and antihelmintic mebendazole on melanome ells in vitro and in vivo
Melanom je vrlo agresivna forma tumora kože, koja je u većini sluĉajeva
rezistentna na konvencionalnu hemioterapiju. Zbog toga melanom predstavlja veliki
izazov za istraživanje novih terapijskih pristupa. Rezultati, dobijeni na animalnim
modelima, ukazuju da helminti ili njihovi ekskretorno-sekretorni (ES) produkti mogu da
modulišu imuni sistem domaćina, i tako dovedu do smanjivanja intenziteta ili
spreĉavanja razvoja autoimunih, alergijskih i malignih bolesti. Sa druge strane, lekovi
koji su odobreni za razliĉite indikacije ali ne i za terapiju kancera, a koji poseduju
prethodno neprepoznat citotoksiĉni efekat prema malignim ćelijama, mogli bi se brzo
naći u primeni i za ovu novu indikaciju. Rezultati dobijeni u in vitro i in vivo uslovima
pokazuju da bi jedan od takvih lekova mogao biti mebendazol. Mebendazol je
antihelmintik, pripada grupi benzimidazola i široko se koristi u veterinarskoj i humanoj
medicini.
U ovom radu posebnu pažnju usmerili smo na analizu dejstva ES produkata
mišićnih, infektivnih larvi (L1) Trichinella spiralis i mebendazola na melanomske ćelije
I) In vitro ispitivanja:
a) Ispitivali smo efekat ES L1 antigena i mebendazola na preživljavanje
melanomskih ćelija. Humane (Fem-X) i mišje (B16) melanomske ćelije gajene su u
jednom sloju i posle 20h tretirane sa po pet rastućih koncentracija ispitivanih supstanci
(ES L1 antigen: 12.5–200 μg/ml, i mebendazol: 0.007-2.5μM) u kompletnom
hranljivom medijumu. Kontrola se sastojala od ćelija gajenih u samom medijumu.
Preživljavanje ćelija je odreĊivano korišćenjem metode redukcije dimetiltiazol difenil
tetrazolijum bromida (MTT test) 72 sata nakon dodavanja antigena. Dobijeni rezultati
ukazuju da ES L1 sntigen T. spiralis na statistiĉki znaĉajan naĉin ispoljava blago
smanjenje preživljavanja kod obe melanomske linije. Mebendazol je, takoĊe, doveo do
smanjenja preživljavanja kod melanomskih ćelija. Kod obe ispitivane supstance ustanovljeno je da je jaĉi efekat prema humanim melanomskim ćelijama nego prema
mišjim, ali to nije bilo statistiĉki znaĉajno...Melanoma is a very aggressive form of skin cancer. It is in most cases resistant to
conventional chemotherapy. Because of that it represents a great challenge for
investigation of new therapeutic approaches. It is well known that co infection with
different pathogens, including helminths and in particular Trichinella spiralis (T. spiralis),
can ameliorate (alter) the progression of different diseases (autoimmune, allergic)
including malignant one. Drugs approved for indications other than cancer that possess
previously unrecognized cytotoxicity toward malignant cells could be rapidly used for this
new indication. Data suggest that one of drugs with such indication could be mebendazole.
Benzimidazole anthelmintics including mebendazole are widely used in human and
veterinary medicine.
We studied the in vivo and in vitro effect of: a) T. spiralis excretory-secretory
muscle larvae (ES L1) antigen and b) mebendazole on the melanoma cells.
I) In vitro studies:
a) We investigated the effect of ES L1 antigen and mebendazole on the survival of
melanoma cells. Human melanoma (Fem-x), and mouse melanoma (B16) tumor cells were
cultured as a monolayer and after 20h treated with five different concentrations of
investigated compounds (ES L1 antigen: 12.5–200 μg/ml, and mebendazole: 0.007-2.5μM)
in complete nutrient medium. Control consisted of cell cultivated in medium alone. Cell
survival was determined 72 h later by using reduction of 3-(4,5-Dimethylthiazol-2-yl)-2,5-
diphenyltetrazolium bromide (MTT test). Obtained results indicated that T. spiralis ES L1
antigen, in a statistically significant manner, exerted a mild survival inhibition of target
tumor cell lines. Mebendazole exerted strong inhibition of the survival. With both
compounds stronger effect was determined toward human melanoma tumor cells
compared with the effect on mouse melanoma cells.
b) Also, we investigated the effect of ES L1 antigen (50-200 μg/ml) and
mebendazole (1.25-5μM) on the apoptosis of mouse B16 melanoma cells. Apoptosis was measured after cultivation of the cells for 72h with ES L1 antigen, and for 24h with
mebendazole..
The structure of Green functions in quantum field theory with a general state
In quantum field theory, the Green function is usually calculated as the
expectation value of the time-ordered product of fields over the vacuum. In
some cases, especially in degenerate systems, expectation values over general
states are required. The corresponding Green functions are essentially more
complex than in the vacuum, because they cannot be written in terms of standard
Feynman diagrams. Here, a method is proposed to determine the structure of
these Green functions and to derive nonperturbative equations for them. The
main idea is to transform the cumulants describing correlations into
interaction terms.Comment: 13 pages, 6 figure
Supplementary data for article: Vojislavljević-Vasilev, D.; Janjić, G. V.; Ninković, D.; Kapor, A.; Zarić, S. The Influence of Water Molecule Coordination onto the Water-Aromatic Interaction. Strong Interactions of Water Coordinating to a Metal Ion. CrystEngComm 2013, 15 (11), 2099–2105. https://doi.org/10.1039/c2ce25621e
Supplementary material for: [https://doi.org/10.1039/c2ce25621e]Related to published version: [http://cherry.chem.bg.ac.rs/handle/123456789/1602
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