21 research outputs found
Noncovalent Interactions of Hydrated DNA and RNA Mapped by 2D-IR Spectroscopy
Biomolecules couple to their aqueous environment through a variety of
noncovalent interactions. Local structures at the surface of DNA and RNA are
frequently determined by hydrogen bonds with water molecules, complemented by
non-specific electrostatic and many-body interactions. Structural fluctuations
of the water shell result in fluctuating Coulomb forces on polar and/or ionic
groups of the biomolecular structure and in a breaking and reformation of
hydrogen bonds. Two-dimensional infrared (2D-IR) spectroscopy of vibrational
modes of DNA and RNA gives insight into local hydration geometries, elementary
molecular dynamics, and the mechanisms behind them. In this chapter, recent
results from 2D-IR spectroscopy of native and artificial DNA and RNA are
presented, together with theoretical calculations of molecular couplings and
molecular dynamics simulations. Backbone vibrations of DNA and RNA are
established as sensitive noninvasive probes of the complex behavior of hydrated
helices. The results reveal the femtosecond fluctuation dynamics of the water
shell, the short-range character of Coulomb interactions, and the strength and
fluctuation amplitudes of interfacial electric fields.Comment: To appear as Chapter 8 of Springer Series in Optical Sciences:
Coherent Multidimensional Spectroscopy -- Editors: Cho, Minhaeng (Ed.), 201
Evaluation of new classifications of N descriptor in non-small cell lung cancer (NSCLC) based on the number and the ratio of metastatic lymph nodes
Intensyfikacja konwekcyjnej wymiany ciepła przez mechaniczne zrywanie termicznej warstwy przyściennej
W pracy zaprezentowano metodę intensyfikacji wymiany ciepła za pomocą mechanicznego zaburzania termicznej warstwy przyściennej. Podano metodę wyznaczania współczynnika wnikania ciepła w takich warunkach oraz przedstawiono wyniki badań eksperymentalnych. Mechaniczne zrywanie termicznej warstwy przyściennej jest jedną z aktywnych metod intensyfikacji wymiany ciepła. Laminarna warstwa przyścienna temperatury stanowi główny opór cieplny w procesie wymiany ciepła. Usunięcie tej warstwy za pomocą obrotowych elementów mechanicznych (skrobaków) skutkuje zmniejszeniem całkowitego oporu przenikania ciepła, a przez to zwiększeniem przekazywanego strumienia ciepła. Badania przeprowadzono na specjalnie do tego celu zaprojektowanym stanowisku eksperymentalnym. Czynnikiem roboczym było powietrze. Zbadano wpływ prędkości obrotowej łopatek skrobiących na wymianę ciepła. Wyniki badań zostały zaprezentowane w formie wykresów
Numerical study on mechanical removing of thermal boundary layer for infinite scrapers cascade
The aim of the study is to examine the impact of the gap between the tip of the scraping blade (scraper) and the wall on the heat transfer. Numerical simulations of heat transfer and fluid flow under mechanical removing of thermal boundary layer were conducted. Due to the complexity of the phenomenon calculations were simplified to the two-dimensional case. As a test case a heat transfer under removing thermal boundary layer via infinite, rectangular scrapers cascade was chosen. Calculations were carried out for different scraper heights, ie. for different gap values. Reynolds and Grashof numbers were constant and equalled 1000 and 10 000 respectively. The range of Prandtl number and the gap varied 0.7-56.0 and 0.005L-0.25L accordingly. The results showed that heat transfer intensification increases with the increasing Prandtl. It was shown that gap value strongly influences both temperature distribution and heat transfer rate. With the decreasing gap heat transfer rate increases
On numerical modelling of heat transfer and fluid flow in a scraped surface heat exchanger
Steady state two-dimensional numerical simulation of laminar heat transfer and fluid flow in a scraped surface heat exchanger (SSHE) is presented. Typical SSHE consists of a stator, rotating shaft and scraping blades. Due to symmetry only a quarter of the heat exchanger is modelled. Governing equations for transport of mass, momentum and energy are discretised and solved with the use of commercial CFD code. The results are presented in a nondimensional form for velocity, pressure and temperature distributions. Local and averaged Nusselt number along the stator wall are calculated and depicted in graphs. It was found that the thirty fold increase of the cReynolds number, leads to heat transfer enhancement rate by three times
3D printing, as a tool for planning orthopedic surgery
Celem przeglądu literatury jest wyznaczenie zakresu zastosowań wydruków 3D uzyskiwanych w technologii druku przyrostowego CJP oraz 3DP w obrębie nauk przyrodniczych, ze szczególnym naciskiem na wykorzystanie ich do planowania zabiegów ortopedycznych o wysokim stopniu komplikacji. Badania nad stosowaną metodą będą związane w ścisłej korelacji z aspektem finansowym. Badacze przyjmują za aksjomat fakt, iż głównym nabywcą będzie jednostka poddana leczeniu (pacjent), odbiorcą natomiast podmiot lub osoba udzielająca jej pomocy (lekarz). Przy wykorzystaniu dostępnych otwarto-źródłowych rozwiązań programowych oraz odpowiedniej metodzie obróbki wyników badań CT, bazującej na algorytmie filtrów dla plików RAW, udało się uzyskać pierwsze relatywnie satysfakcjonujące efekty. Pozwalają one na prawie całkowite wykluczenie ludzkiej pracy z jednego z najtrudniejszych i najbardziej czasochłonnych procesów – jaki wpisz. Koszt całkowity (brutto) komercyjnego wydruku 3D, z uwzględnieniem wszystkich procesów produkcyjnych oraz poprodukcyjnych, jest średnio do 50% niższy od stawek komercyjnych dla modelu (os coxae) miednicy wraz z „os femoris” kością udową nieprzekraczającą długości 20 cm. Jest to efekt ”względnie pozytywny”. Mimo niewątpliwego sukcesu w zakresie kosztów druku 3D, będzie się dążyć do zmniejszenia kosztu wydruku o kolejne 30% (liczone od kwoty bazowej) poprzez wprowadzanie maszynowej obróbki oraz automatyzacji zadań oraz stosowanie innych metod druku. Zastosowanie wydruków 3D przy szeroko pojętym planowaniu zabiegów ortopedycznych, pozwala na znaczące zmniejszenie użycia instrumentarium oraz czasu zabiegu, w odniesieniu do przeprowadzonych podobnych działań, nieuwzględniających w swoim zakresie wydruku 3D.The purpose of the literature review is to determine the scope of 3D printing, also known as RP (Rapid Prototyping) applications in manufacturing medical model based on CJP (Collor Jet Printing) technology, with emphasis on the use in orthopedic surgery planning. The research of the presented method will be focused on the financial aspect. Researchers accept as axiomatic fact that the main buyer of the MRP (Medical Rapid Prototyping) structure will be the patient while the recipient will be the doctor or surgeon that provides the operation. Using available open-source software solutions and suitable method for the treatment of CT (Computed Tomography) scans based on filtering RAW files managed we to get the best or relatively good results allowing to exclude a human work from one of the most difficult and time-consuming processes. Total cost of 3D printings including all production processes and post-productions are about 50% lower than commercial rates (on free market) for the model of: “oscoxae” including "osfemoris" (femur length not exceeding 20 cm). In our opinion it’s "relatively positive" effect. Despite the success in the field of lowering the cost of 3D prints our work is still focused on reducing it (at least up to another 30%) by using automated-machine processing and tasks automation, as well as using another printing methods. Using 3D printings as a tools to help plan complex orthopedic surgeries make possible to extremely reduce the time of using instrumentation and the treatment time (comparing to similar surgeries carried out without using 3D printings)
Design, Integration, and Control of Organic Rankine Cycles with Thermal Energy Storage and Two-Phase Expansion System Utilizing Intermittent and Fluctuating Heat Sources—A Review
Abstract: In order to lessen reliance on fossil fuels, a rise in interest in the utilization of fluctuating and intermittent heat sources derived from renewable energy (such as solar thermal, ocean thermal, and geothermal) and waste heat has been observed. These heat sources could be used to generate electricity at relatively low and medium temperatures, for example, through the organic Rankine cycle (ORC). In some case studies, various approaches have been developed to deal with and design ORCs in the desired operating condition utilizing suitable working fluids. This article aims to review some designs and integrated systems of ORC with thermal energy storage (TES) and a twophase expansion system focusing on the utilization of medium- and low-temperature heat sources in which some subcritical ORCs are presented. Moreover, several possible control systems (both conventional and advanced ones) of ORC with TES and a two-phase expansion system are reported and compared. At the end of this article, the possible future developments of design and control systems are discussed to describe advanced ORC for utilizing low-grade heat sources. This study aims to provide researchers and engineers with an insight into the challenges involved in this process, making industrialization of ORC technology more extensive, in particular when combined with TES and a two-phase expansion system
The use of biodegradable materials in dentistry : a review of the literature
W zależności od rodzaju utraconej struktury tkankowej
w obrębie układu stomatognatycznego lub przerwania
jej ciągłości mogą być wykorzystywane różne biomateriały,
które powinny spełniać określone właściwości mechaniczne.
Stosowane implanty, skafoldy, a także śruby, mikropłytki lub
klamry zazwyczaj wykonane są z tytanu lub jego stopów. Postęp
w dziedzinie biomateriałów spowodował, iż współcześnie wykorzystywane
są również materiały biodegradowalne, które po
spełnieniu swojej funkcji reparacyjnej ulegają samoistnej degradacji
(tj. nici chirurgiczne). W pracy przeanalizowano piśmiennictwo
dotyczące wykorzystania materiałów biodegradowalnych
w stomatologii.Depending on the type of the lost tissue within the stomatognathic
system or breaking of its continuity, various biomaterials
having proper mechanical properties can be used. Applied
implants, scafolds as well as screws, micro-plates or clamps are
usually made of titanium or its alloys. Advances in the field of
biomaterials caused that nowadays biodegradable materials are
used, and after their reparative function become self-degrading
(ie. surgical stitches). The paper analyzes the literature regarding
the use of biodegradable materials in dentistry
64 channel neural recording amplifier with tunable bandwidth in 180 nm CMOS technology
This paper presents the design and measurements of low-noise multichannel front-end electronics for recording extra-cellular neuronal signals using microelectrode arrays. The integrated circuit contains 64 readout channels and is fabricated in CMOS 180 nm technology. A single readout channel is built of an AC coupling circuit at the input, a low-noise preamplifier, a band-pass filter and a second amplifier. In order to reduce the number of output lines, the 64 analog signals from readout channels are multiplexed to a single output by an analog multiplexer. The chip is optimized for low noise and good matching performance and has the possibility of passband tuning. The low cut-off frequency can be tuned in the 1 Hz - 60 Hz range while the high cut-off frequency can be tuned in the 3.5 kHz - 15 kHz range. For the nominal gain setting at 44 dB and power dissipation per single channel of 220 žW, the equivalent input noise is in the range from 6 žV - 11 žV rms depending on the band-pass filter settings. The chip has good uniformity concerning the spread of its electrical parameters from channel to channel. The spread of the gain calculated as standard deviation to mean value is about 4.4% and the spread of the low cut-off frequency set at 1.6 Hz is only 0.07 Hz. The chip occupies 5×2.3 mm⊃2 of silicon area. To our knowledge, our solution is the first reported multichannel recording system which allows to set in each recording channel the low cut-off frequency within a single Hz with a small spread of this parameter from channel to channel. The first recordings of action potentials from the thalamus of the rat under urethane anesthesia are presented