1,724,353 research outputs found
Tissue differentiation around a short stemmed metaphyseal loading implant employing a modified mechanoregulatory algorithm: a finite element study
No full textShort stemmed cementless implants are being used increasingly to avoid problems associated with their long stemmed counterparts such as size, stiffness, and bulky nature, which can contribute to stress shielding, fractures, and hence loosening. They are also thought to enhance physiological loading of the femur. We performed a computational investigation of the possible tissue differentiation and bone ingrowth processes for a specific type of stemless implant using a mechanoregulatory hypothesis, with modifications to simulate tissue differentiation, and simplified loading conditions. The peak forces during stair climbing and normal walking were investigated to evaluate their influence on the process. The results were compared to clinical studies for relevance and corroboration. The majority of the tissue type formed was fibrous, occupying the proximal regions of the implant. The lateral flare design feature of the implant was predicted to enhance bone and cartilage formation in regions beneath it compared to the same design without a flare. The percentage of bone formed increased through the iterations and accounted for nearly 35% of the tissue at the end of the iterations in Gruen zones 2 and 6, replacing cartilage tissue as differentiation progressed. This agreed well with clinical data showing similar regions of bone formation and suggests that the distal regions of the implant under the lateral flare, resting in the metaphyseal region of the bone, promoted implant stability
Excited-state intramolecular proton transfer of 2-acetylindan-1,3-dione studied by ultrafast absorption and fluorescence spectroscopy
Full text linkWe employ transient absorption from the deep-UV to the visible region and fluorescence upconversion to investigate the photoinduced excited-state intramolecular proton-transfer dynamics in a biologically relevant drug molecule, 2-acetylindan- 1,3-dione. The molecule is a ß-diketone which in the electronic ground state exists as exocyclic enol with an intramolecular H-bond. Upon electronic excitation at 300 nm, the first excited state of the exocyclic enol is initially populated, followed by ultrafast proton transfer (±160 fs) to form the vibrationally hot endocyclic enol. Subsequently, solvent-induced vibrational relaxation takes place (±10 ps) followed by decay (±390 ps) to the corresponding ground state. © 2015 Author(s)1561sciescopu
Simulation of tissue differentiation in uncemented hip implants based on a mechanoregulatory hypothesis
No full textEThOS - Electronic Theses Online ServiceGBUnited Kingdo
How Molecular Crowding Differs from Macromolecular Crowding: A Femtosecond Mid-Infrared Pump–Probe Study
No full textCrowding is an inherent
property of living systems in which biochemical
processes occur in highly concentrated solutions of various finite-sized
species of both low (molecular crowding) and high (macromolecular
crowding) molecular weights. Is molecular crowding fundamentally different
from macromolecular crowding? To answer this question, we use a femtosecond
mid-infrared pump–probe technique with three vibrational probes
in molecular (diethylene glycol) and macromolecular (polyethylene
glycol) solutions. In less crowded media, both molecular and macromolecular
crowders fail to affect the dynamics of interstitial bulk-like water
molecules and those at the crowder/water interface. In highly crowded
media, interstitial water dynamics strongly depends on molecular crowding,
but macromolecular crowding does not alter the bulk-like hydration
dynamics and has a modest crowding effect on water at the crowder/water
interface. The results of this study provide a molecular level understanding
of the structural and dynamic changes to water and the water-mediated
cross-linking of crowders
Water Dynamics in Cytoplasm-Like Crowded Environment Correlates with the Conformational Transition of the Macromolecular Crowder
No full textPolyethylene glycol (PEG) is a unique polymer material with enormous applicability in many industrial and scientific fields. Here, its use as macromolecular crowder to mimic the cellular environment in vitro is the focus of the present study. We show that femtosecond mid-IR pump–probe spectroscopy using three different IR probes, HDO, HN3, and azido-derivatized crowder, provides complete and stereoscopic information on water structure and dynamics in the cytoplasm-like macromolecular crowding environment. Our experimental results suggest two distinct subpopulations of water molecules: those that interact with other water molecules and those that are part of a hydration shell of crowder on its surface. Interestingly, water dynamics even in highly crowded environment remains bulk-like in spite of significant perturbation to the tetrahedral H-bonding network of water molecules. That is possible because of the formation of water aggregates (pools) even in water-deficient PEGDME-water solutions. In such a crowded environment, the conformationally accessible phase space of the macromolecular crowder is reduced, similar to biopolymers in highly crowded cytoplasm. Nonetheless, the hydration water on the surface of crowders slows down considerably with increased crowding. Most importantly, we do not observe any coalescing of surface hydration water (of the crowder) with bulk-like water to generate collective hydration dynamics at any crowder concentration, contrary to recent reports. We anticipate that the present triple-IR-probe approach is of exceptional use in studying how conformational states of crowders correlate with structural and dynamical changes of water, which is critical in understanding their key roles in biological and industrial applications.
© 2016 American Chemical Society19101sciescopu
Mystus prabini, a new species of catfish (Siluriformes: Bagridae) from Arunachal Pradesh, north-eastern, India
No full textDarshan, Achom, Abujam, Santoshkumar, Kumar, Ram, Parhi, Janmejay, Singh, Yambem Suresh, Vishwanath, Waikhom, Das, Debangshu Narayan, Pandey, Pramod Kumar (2019): Mystus prabini, a new species of catfish (Siluriformes: Bagridae) from Arunachal Pradesh, north-eastern, India. Zootaxa 4648 (3): 511-522, DOI: 10.11646/zootaxa.4648.3.
The Bend plus Libration Combination Band Is an Intrinsic, Collective, and Strongly Solute-Dependent Reporter on the Hydrogen Bonding Network of Liquid Water
Full text linkWater is an extensively self-associated liquid due to its extensive hydrogen bond (H-bond) forming ability. The resulting H-bonded network fluid exhibits nearly continuous absorption of light from the terahertz to the near-IR region. The relatively weak bend+libration water combination band (centered at 2130 cm(-1)) has been largely overlooked as a reporter of liquid water's structure and dynamics despite its location in a convenient region of the IR for spectroscopic study. The intermolecular nature of the combination band leads to a unique absorption signal that reports collectively on the rigidity of the H-bonding network in the presence of many different solutes. This study reports comprehensively how the combination band acts as an intrinsic and collective probe in various chemically and biologically relevant solutions, including salts of varying character, denaturants, osmolytes, crowders, and surfactants that form reverse micelles and micelles. While we remark on changes in the line width and intensity of this combination band, we mainly focus on the frequency and how the frequency reports on the collective H-bonding network of liquid water. We also comment on the "association band" moniker often applied to this band and how to evaluate discrete features in this spectral region that sometimes appear in the IR spectra of specific kinds of aqueous samples of organic solutes, especially those with very high solute concentrations, with the conclusion that most of these discrete spectral features come exclusively from the solutes and do not report on the water. Contrasts are drawn throughout this work between the collective and delocalized reporting ability of the combination band and the response of more site-specific vibrations like the much-investigated OD stretch of HDO in H2O: the combination band is a unique reporter of H-bonding structure and dynamics and fundamentally different than any local mode probe. Since this band appears as the spectroscopic "background" for many local-mode reporter groups, we note the possibility of observing both local and collective solvent dynamics at the same time in this spectral region
© 2017 American Chemical Society
Evaluation of Relative Operational Performance and Measurement Functionality of Wave Measuring Instruments
No full text© 2022 Pramod Kumar JangirAccurate ocean wave measurements are needed for the safe design and operation of offshore facilities, but despite the availability of ocean wave measurements, wave analysis remains troubled by continuing uncertainty on what exactly the instruments are measuring and the accuracy of those measurements. Of paramount importance are measurements during extreme sea states. We examine wave measurements made with an Optech Laser, a Rosemount WaveRadar, and a Datawell Waverider buoy at North Rankin A platform (NRA), Australia; Ekofisk, the North Sea; and the South China Sea. We evaluate the relative performance of these instruments based upon various time and frequency domain comparisons. The time-domain investigation includes results from quality controlled (QC) measurements of the wave surface profile (skewness), and crest heights for varying wind sea, and swell conditions. In the frequency domain comparison, we examine one-dimensional frequency spectra using spectrogram, spectral moments, high-frequency tail slopes, and significant wave heights and second moment periods derived from wave spectra. The spectral relationship (transfer function) in terms of the mean spectral ratio of the instruments is established which can be used for spectral calibration. In addition, the functionality of the instruments using linear simulation is examined, providing an overview of how instrumentation setups might affect actual wave measurements. The results from the various time and frequency domain comparisons and linear simulations allow us to draw conclusions as to the performance of these instruments and the most likely cause of the discrepancies in the measurements
Smoking, nicotine and the kidney
Full text linkTerwijl roken schadelijk is voor de nieren, lijkt nicotine juist een beschermend effect op deze organen te hebben. Matige alcoholconsumptie lijkt positieve effecten te hebben na niertransplantatie: het vermindert het risico op overlijden en het ontstaan van diabetes. Dat blijkt uit onderzoek van Pramod Kumar Agarwal. Er zijn tal van factoren bekend die het risico op nierfalen vergroten: diabetes, hoge bloeddruk en overgewicht zijn bekende risicofactoren. Maar ook zoutinname, gebrek aan lichamelijke activiteit en slaap, en psychosociale stress spelen een rol. Agarwal bracht de gevaren van roken en alcohol na niertransplantatie nader in kaart. Hij stelt vast dat de nierfunctie van rokers sneller afneemt dan die van niet-rokers en ex-rokers. Sigarettenrook bevat tal van schadelijke stoffen, waarvan nicotine het bekendst en meest verslavend is. Uit eerdere studies bleek echter dat nicotine een remmende werking heeft op ontstekingen. Uit het onderzoek van Agarwal blijkt dat een nicotinebehandeling - in een diermodel - nierfalen vermindert. Wellicht zijn middelen die worden gebruikt om te stoppen met roken dus ook geschikt ter bescherming van de nieren. Verder blijkt na een niertransplantatie matige alcoholconsumptie een positief effect te hebben. Het risico op overlijden en diabetes neemt vooral af wanneer de patiënt niet rookt
Supplemental Material, Figure_E2A-E2C - Bentall’s Procedure for Annuloaortic Ectasia and Severe Aortic Regurgitation in a Patient With Repaired Tetralogy of Fallot and Aortic Valvular Reconstruction
No full textSupplemental Material, Figure_E2A-E2C for Bentall’s Procedure for Annuloaortic Ectasia and Severe Aortic Regurgitation in a Patient With Repaired Tetralogy of Fallot and Aortic Valvular Reconstruction by Ujjwal Kumar Chowdhury, Niwin George, Vasubabu Gudala, Anish Gupta, Sheil Avneesh, Lakshmi Kumari Sankhyan, Vishwas Malik and Pramod Kumar in World Journal for Pediatric and Congenital Heart Surgery</p
- …
