46 research outputs found
The effect of stress-induced martensite aging in tension and compression on B2–B19′ martensitic transformation in Ni50.3Ti32.2Hf17.5 high-temperature shape memory alloy
The present study investigates the high-temperature shape memory effect (SME) in heterophase Ni50.3Ti32.2Hf17.5 polycrystals with nanosized H-phase particles after stress-induced martensite (SIM) aging in tension and compression. SIM aging created the conditions for fully reversible two-way SME with a strain of up to 50% of the one-way shape memory strain. SIM aging altered the viscoelastic properties of material, in particular, the elastic moduli of austenite and martensite increased, as did internal friction. Increased interface mobility is suggested as the reason for internal friction growth
Analysis of Nematic Liquid Crystals with Disclination Lines
We investigate the structure of nematic liquid crystal thin films described
by the Landau--de Gennes tensor-valued order parameter with Dirichlet boundary
conditions of nonzero degree. We prove that as the elasticity constant goes to
zero a limiting uniaxial texture forms with disclination lines corresponding to
a finite number of defects, all of degree 1/2 or all of degree -1/2. We also
state a result on the limiting behavior of minimizers of the Chern-Simons-Higgs
model without magnetic field that follows from a similar proof.Comment: 40 pages, 1 figur
Multi-level Dynamical Systems: Connecting the Ruelle Response Theory and the Mori-Zwanzig Approach
In this paper we consider the problem of deriving approximate autonomous
dynamics for a number of variables of a dynamical system, which are weakly
coupled to the remaining variables. In a previous paper we have used the Ruelle
response theory on such a weakly coupled system to construct a surrogate
dynamics, such that the expectation value of any observable agrees, up to
second order in the coupling strength, to its expectation evaluated on the full
dynamics. We show here that such surrogate dynamics agree up to second order to
an expansion of the Mori-Zwanzig projected dynamics. This implies that the
parametrizations of unresolved processes suited for prediction and for the
representation of long term statistical properties are closely related, if one
takes into account, in addition to the widely adopted stochastic forcing, the
often neglected memory effects.Comment: 14 pages, 1 figur
Microbial landscape patients with advanced sterile pancreatic necrosis in the dynamics of complex treatment
Method of gas chromatography - mass spectrometry was used for the study of microbial landscape of patients with pancreatonecrosis. It was found that the provision of sterile necrotic destruction dysbiosis occurs that requires correction during the treatment. Unlike conventional methods of diagnosis of infection pancreatogenic gas chromatography - mass spectrometry allows to express mode (3 hours) monitored landscape microbial degradation pancreatogenic patients. In patients with necrotizing pancreatitis concentration of organisms was determined in serum on admission, on day 5, day 10, day 15, day 20 of treatment. Data on the composition of microorganisms, participants of widespread sterile necrotic destruction when assessing the overall microecological status, obtained for each patient allow to get a qualitatively new comprehensive information to make adequate antibiotic therapy and complex treatment that significantly broadens the etiology of this disease
Mean square displacement and reorientational correlation function in entangled polymer melts revealed by field cycling 1H and 2H NMR relaxometry
Mixtures of protonated and deuterated polybutadiene and polydimethylsiloxane are studied by means of field-cycling (FC) 1H NMR relaxometry in order to analyze the intra- and intermolecular contributions to spin-lattice relaxation. They reflect reorientational and translational dynamics,respectively. Master curves in the susceptibility representation π″(ωτ s) are constructed by employing frequency-temperature superposition with τ s denoting the segmental correlation time. The intermolecular contribution is dominating at low frequencies and allows extracting the segmental mean square displacement 〈R 2(t)〉, which reveals two power-law regimes. The one at short times agrees with t 0.5 predicted for the free Rouse regime and at long times a lower exponent is observed in fair agreement with t 0.25 expected for the constrained Rouse regime of the tube-reptation model. Concomitantly the reorientational rank-two correlation function C 2(t/τ s) is obtained from the intramolecular part. Again two power-law regimes t -ε are identified for polybutadiene. The first agrees with t -1 of free Rouse dynamics whereas at long times ε = 0.49 is obtained. The latter is corroborated by the 2H relaxation of deuterated polybutadiene, yet, it does not agree with ε = 0.25 predicted for constrained Rouse dynamics. Thus, the relation C 2(t) ∝ 〈R 2(t)〉 -1 as assumed by the tube-reptation model is not confirmed. © 2012 American Chemical Society
Molecular Plasmonic Silver Forests for the Photocatalytic-Driven Sensing Platforms
Structural electronics, as well as flexible and wearable devices are applications that are possible by merging polymers with metal nanoparticles. However, using conventional technologies, it is challenging to fabricate plasmonic structures that remain flexible. We developed three-dimensional (3D) plasmonic nanostructures/polymer sensors via single-step laser processing and further functionalization with 4-nitrobenzenethiol (4-NBT) as a molecular probe. These sensors allow ultrasensitive detection with surface-enhanced Raman spectroscopy (SERS). We tracked the 4-NBT plasmonic enhancement and changes in its vibrational spectrum under the chemical environment perturbations. As a model system, we investigated the sensor’s performance when exposed to prostate cancer cells’ media over 7 days showing the possibility of identifying the cell death reflected in the environment through the effects on the 4-NBT probe. Thus, the fabricated sensor could have an impact on the monitoring of the cancer treatment process. Moreover, the laser-driven nanoparticles/polymer intermixing resulted in a free-form electrically conductive composite that withstands over 1000 bending cycles without losing electrical properties. Our results bridge the gap between plasmonic sensing with SERS and flexible electronics in a scalable, energy-efficient, inexpensive, and environmentally friendly way.</p
Oral squamous cell carcinoma in "young" patients
Aim of the study — to provide for medical oncologists and surgeon, who specialize in treatment of head and neck oncology patients, the most recent information about incidence and feature of oral squamous cell carcinoma (OSCC) in young patientsЦель исследования — предоставить онкологам и хирургам, специализирующимся на лечении пациентов, страдающих раком головы и шеи, наиболее полную информацию о распространенности и особенностях плоскоклеточного рака полости рта у «молодых» пациентов на основе последних литературных данны
Клинический случай метастаза рака носоглотки в щитовидную железу
Background. Nasopharyngeal cancer is a rare head and neck cancer with a relatively high risk of locoregional recurrence and distant metastases. The most common sites of metastases are bones (70–80 %) followed by liver (30 %), lung (18 %), and lymph node (axillary, mediastinal, pelvic, and inguinal). Thyroid gland is an uncommon site of metastasis with an incidence ranging from 0.5% to 24 %. Thyroid metastasis from nasopharyngeal cancer has been reported in only 9 cases in the world literature and no one in Russia. Case report. We report a case of thyroid metastasis from nasopharyngeal cancer found incidentally in a 53-year-old female patient. Conclusion. Metastases to the thyroid gland are rare, and patients with metastatic thyroid disease rarely present with organ-specifc symptoms, thus raising diagnostic diffculties for both clinicians and the pathologists. This clinical report demonstrates the diffculties of differential diagnosis,as well as the importance of a thorough collection of complaints, anamnesis, and clinical examination.Актуальность. Рак носоглотки относится к редким заболеваниям в структуре опухолей головы и шеи. Данное новообразование имеет относительно высокий риск метастазов в регионарные лимфоузлы и отдаленные органы-мишени. Наиболее часто отдаленное метастазирование происходит в кости (70–80 %), печень (30 %), легкие (18 %), а также лимфоузлы (подмышечные, средостения, малого таза, паховые). Метастазы в щитовидную железу являются редким событием и встречаются в 0,5–24 % случаев. В мировой литературе описано 9 случаев метастазов рака носоглотки в щитовидную железу, подобных сообщений в отечественной литературе не найдено. Описание клинического случая. Представлено клиническое наблюдение 53-летней пациентки, у которой первично выявлен метастаз рака носоглотки в щитовидную железу как случайная находка. Заключение. Щитовидная железа редко является органом-мишенью для метастазов, при этом ее метастатическое поражение обычно не сопровождается функциональными нарушениями. По этой причине его диагностика является затруднительной как для клинициста, так и для патолога. Данный клинический случай демонстрирует трудности дифференциальной диагностики, а также показывает важность тщательного сбора жалоб, анамнеза, клинического осмотра.
Liquid crystals and their defects
These lecture notes discuss classical models of liquid crystals, and the
different ways in which defects are described according to the different
models.Comment: CIME lecture course, Cetraro, 201