Microstructural comparison of synthetic bioceramics with natural bioceramics

1991 ◽  
Vol 49 ◽  
pp. 38-39
Author(s):  
Shulin Wen ◽  
Jingwei Feng ◽  
A. Krajewski ◽  
A. Ravaglioli
Keyword(s):  
Recent Work ◽  
Human Body ◽  
Human Tissues ◽  
Main Constituent ◽  
Laboratory Furnace ◽  
Chinese Adult ◽  
Human Enamel ◽  
Biological Compatibility ◽  
Synthetic Hydroxyapatite ◽  
Synthetic Work

Hydroxyapatite bioceramics has attracted many material scientists as it is the main constituent of the bone and the teeth in human body. The synthesis of the bioceramics has been performed for years. Nowadays, the synthetic work is not only focused on the hydroapatite but also on the fluorapatite and chlorapatite bioceramics since later materials have also biological compatibility with human tissues; and they may also be very promising for clinic purpose. However, in comparison of the synthetic bioceramics with natural one on microstructure, a great differences were observed according to our previous results. We have investigated these differences further in this work since they are very important to appraise the synthetic bioceramics for their clinic application.The synthetic hydroxyapatite and chlorapatite were prepared according to A. Krajewski and A. Ravaglioli and their recent work. The briquettes from different hydroxyapatite or chlorapatite powders were fired in a laboratory furnace at the temperature of 900-1300°C. The samples of human enamel selected for the comparison with synthetic bioceramics were from Chinese adult teeth.

Microstructure of bioceramic chloroapatite

1990 ◽  
Vol 48 (4) ◽  
pp. 1042-1043
Author(s):  
Jingwei Feng ◽  
Shulin Wen ◽  
A. Ravaglioli
Keyword(s):  
Human Tissues ◽  
Important Class ◽  
Main Constituent ◽  
Monoclinic System ◽  
Hexagonal System ◽  
Space Group ◽  
Chlorinated Compound ◽  
Bioactive Properties ◽  
Biological Compatibility ◽  
Hydroxyl Apatite

Bioceramics has drawn the attention of scientists working at the solid state field. The main constituent of bone and teeth in human body is Ca10(PO4)6(OH)2. So this compound and its derivatives form a first important class of particular bioceramic materials. Chloroapatite is a member of this compound family. We synthesized a series of chloroapatite at increasing content of chlorine in comparison with the hydroxyl- apatite in order to search better bioceramics which has not only large biological compatibility with human tissues, but also exert bioactive properties. We found that in comparison with hydroxylapatite all the structures are very similar among them at the level of atomic arrangement. However, in the case of high chlorinated compound, like Ca10(PO4)Cl2, the structure would transform to monoclinic system with space group P21/a from original hexagonal system with space group P63/m. Only in the case of low chlorinated compound, the structure would be kept to be hexagonal system with space group P63/m.

The Crisis of Becoming-Nature in Howard Barker’s Recent Dramas

2020 ◽  
Vol 8 (1) ◽  
pp. 100-114
Author(s):  
Karoline Gritzner
Keyword(s):  
Recent Work ◽  
Human Body ◽  
Elderly Women ◽  
Young Men ◽  
Human Agency ◽  
The Self ◽  
Love Relationships ◽  
Late Style ◽  
Life Force ◽  
The Individual

AbstractThis article discusses how in Howard Barker’s recent work the idea of the subject’s crisis hinges on the introduction of an impersonal or transpersonal life force that persists beyond human agency. The article considers Barker’s metaphorical treatment of the images of land and stone and their interrelationship with the human body, where the notion of subjective crisis results from an awareness of objective forces that transcend the self. In “Immense Kiss” (2018) and “Critique of Pure Feeling” (2018), the idea of crisis, whilst still dominant, seems to lose its intermittent character of singular rupture and reveals itself as a permanent force of dissolution and reification. In these plays, the evocation of nonhuman nature in the love relationships between young men and elderly women affirms the existence of something that goes beyond the individual, which Barker approaches with a late-style poetic sensibility.

Hydroxyapatite and Carbonated Apatite as Models for the Dissolution Behavior of Human Dental Enamel

1987 ◽  
Vol 1 (2) ◽  
pp. 314-321 ◽  
Author(s):  
J.A. Budz ◽  
M. Lore ◽  
G.H. Nancollas
Keyword(s):  
Driving Forces ◽  
Dental Enamel ◽  
Dissolution Behavior ◽  
Constant Composition ◽  
Interesting Phenomenon ◽  
Carbonated Apatite ◽  
Human Enamel ◽  
Synthetic Hydroxyapatite ◽  
Intact Surface

It is now well-established that kinetic aspects as well as considerations based solely on solubilities and thermodynamic driving forces should be taken into account while one is attempting to understand the mechanism of dental caries. In the present study, kinetic comparisons of the dissolution of hydroxyapatite, carbonated apatite, and ground human dental enamel have been made in order that the appropriateness of these synthetic phases as enamel dissolution models can be assessed. Specific additives used to form intact surface layers in vitro have also been investigated. An interesting phenomenon related to surface-controlled dissolution has been revealed. During Constant Composition experiments, the dissolution rates for all the systems decrease markedly as the reaction proceeds. Further tests with fresh crystals suggest that micro-impurities, in addition to microstructural changes of the dissolving surfaces, may play a role in the case of hydroxyapatite but do not influence the dissolution of carbonated apatite. Kinetic results for ground human enamel indicate the release of dissolution poisons. Nevertheless, the results confirm expectations that carbonated apatite may be a better model for enamel than near-stoichiometric synthetic hydroxyapatite.

scholarly journals On-the-fly selection of cell-specific enhancers, genes, miRNAs and proteins across the human body using SlideBase

Database ◽  
2016 ◽  
Vol 2016 ◽  
Author(s):  
Hans Ienasescu ◽  
Kang Li ◽  
Robin Andersson ◽  
Morana Vitezic ◽  
Sarah Rennie ◽  
...  
Keyword(s):  
Human Body ◽  
Individual Cell ◽  
Cell Types ◽  
Large Datasets ◽  
Human Tissues ◽  
Web Tool ◽  
Expression Of Genes ◽  
Micro Rnas ◽  
Human Protein Atlas ◽  
Selection Of

Genomics consortia have produced large datasets profiling the expression of genes, micro-RNAs, enhancers and more across human tissues or cells. There is a need for intuitive tools to select subsets of such data that is the most relevant for specific studies. To this end, we present SlideBase, a web tool which offers a new way of selecting genes, promoters, enhancers and microRNAs that are preferentially expressed/used in a specified set of cells/tissues, based on the use of interactive sliders. With the help of sliders, SlideBase enables users to define custom expression thresholds for individual cell types/tissues, producing sets of genes, enhancers etc. which satisfy these constraints. Changes in slider settings result in simultaneous changes in the selected sets, updated in real time. SlideBase is linked to major databases from genomics consortia, including FANTOM, GTEx, The Human Protein Atlas and BioGPS. Database URL: http://slidebase.binf.ku.dk

scholarly journals Acetylcholinesterase and Butyrylcholinesterase – Important Enzymes of Human Body

2004 ◽  
Vol 47 (4) ◽  
pp. 215-228 ◽  
Author(s):  
Jiří Patočka ◽  
Kamil Kuča ◽  
Daniel Jun
Keyword(s):  
Reaction Mechanism ◽  
Peripheral Nerve ◽  
Human Body ◽  
Physiological Function ◽  
Human Tissues ◽  
Serine Hydrolases ◽  
Chemical Reaction Mechanism ◽  
Cholinesterase Activities ◽  
Peripheral Nerve System ◽  
Nerve System

The serine hydrolases and proteases are a ubiquitous group of enzymes that is fundamental to many critical lifefunctions. Human tissues have two distinct cholinesterase activities: acetylcholinesterase and butyrylcholinesterase. Acetylcholinesterase functions in the transmission of nerve impulses, whereas the physiological function of butyrylcholinesterase remains unknown. Acetylcholinesterase is one of the crucial enzymes in the central and peripheral nerve system. Organophosphates and carbamates are potent inhibitors of serine hydrolases and well suited probes for investigating the chemical reaction mechanism of the inhibition. Understanding the enzyme’s chemistry is essential in preventing and/or treating organophosphate and carbamate poisoning as well as designing new medicaments for cholinergic-related diseases like as Alzheimer’s disease.

scholarly journals The structure of helical lipoprotein lipase reveals an unexpected twist in lipase storage

2020 ◽  
Vol 117 (19) ◽  
pp. 10254-10264
Author(s):  
Kathryn H. Gunn ◽  
Benjamin S. Roberts ◽  
Fengbin Wang ◽  
Joshua D. Strauss ◽  
Mario J. Borgnia ◽  
...  
Keyword(s):  
Recent Work ◽  
Lipoprotein Lipase ◽  
Human Body ◽  
Crucial Role ◽  
Fluorescent Microscopy ◽  
Heparin Binding ◽  
Helix Formation ◽  
Intracellular Vesicles ◽  
Shed Light

Lipases are enzymes necessary for the proper distribution and utilization of lipids in the human body. Lipoprotein lipase (LPL) is active in capillaries, where it plays a crucial role in preventing dyslipidemia by hydrolyzing triglycerides from packaged lipoproteins. Thirty years ago, the existence of a condensed and inactive LPL oligomer was proposed. Although recent work has shed light on the structure of the LPL monomer, the inactive oligomer remained opaque. Here we present a cryo-EM reconstruction of a helical LPL oligomer at 3.8-Å resolution. Helix formation is concentration-dependent, and helices are composed of inactive dihedral LPL dimers. Heparin binding stabilizes LPL helices, and the presence of substrate triggers helix disassembly. Superresolution fluorescent microscopy of endogenous LPL revealed that LPL adopts a filament-like distribution in vesicles. Mutation of one of the helical LPL interaction interfaces causes loss of the filament-like distribution. Taken together, this suggests that LPL is condensed into its inactive helical form for storage in intracellular vesicles.

Modeling of In-Body Propagation Characterization for 2.5/3.5 GHz Implantable Devices Applications

2013 ◽  
Vol 273 ◽  
pp. 583-587
Author(s):  
Bao Lin Wei ◽  
Hong Wei Yue ◽  
Qian Zhou ◽  
Wei Lin Xu ◽  
Xue Ming Wei ◽  
...  
Keyword(s):  
Human Body ◽  
Implantable Devices ◽  
Human Tissues ◽  
Computational Results ◽  
Mean Square ◽  
Electromagnetic Model ◽  
Power Law Function ◽  
Em Simulation ◽  
Ct And Mri ◽  
Path Gain

To investigate the propagate channel for implantable devices deep inside of a human body to receiver on-body or outside body, a 3D electromagnetic model of human body which including 85 kinds of different human tissues and organs, based on CT and MRI slices data take from living human males, was built. The in-body channel path gain in different distance for 2.5/3.5 GHz biomedical implants was investigated using electromagnetic (EM) simulator and its numerical sta-tistical model was presented. EM simulation and numerical computational results show that the dis-tance dependent path gain for inside body can be modeled by a modificatory classical power law function with root-mean-square error (RMSE) of 2.6 and 3.9 for 2.5 GHz and 3.5 GHz, respectively

Mercury and Lead Content of Human Body Tissues from a Selected Population

1978 ◽  
Vol 18 (3) ◽  
pp. 155-158 ◽  
Author(s):  
Robert Schmidt ◽  
Charles G. Wilber
Keyword(s):  
Human Body ◽  
Mercury Content ◽  
Human Tissues ◽  
Sharp Drop ◽  
Human Organs ◽  
Body Tissues ◽  
Atomic Absorption Technique ◽  
Autopsy Specimens ◽  
Kidney Liver ◽  
Absorption Technique

Organs from 40 cadavers, ranging in age from 1 to 90 years, were analyzed for lead and mercury using the atomic absorption technique. The results show no overall elevated trends in lead and mercury content of human tissues from persons in Northeastern Colorado, USA. The data, when compared with values obtained from autopsy specimens taken 60 years ago, suggest a sharp drop in mercury content of most human organs over that period of time. In general, lead in bone increases with age. Lead in kidney, liver, and muscle decreases with age. Mercury in bone is usually quite low. Mercury in kidney increases with age; in muscle it remains the same; in liver there is only a suggestion of increase with age.

scholarly journals The hidden structure of human enamel

2019 ◽  
Vol 10 (1) ◽  
Author(s):  
Elia Beniash ◽  
Cayla A. Stifler ◽  
Chang-Yu Sun ◽  
Gang Seob Jung ◽  
Zhao Qin ◽  
...  
Keyword(s):  
Molecular Dynamics ◽  
Molecular Dynamics Simulations ◽  
Human Body ◽  
Crack Deflection ◽  
Toughening Mechanism ◽  
Space Filling ◽  
Human Enamel ◽  
Dynamics Simulations ◽  
Physical And Chemical ◽  
Enamel Layer

Abstract Enamel is the hardest and most resilient tissue in the human body. Enamel includes morphologically aligned, parallel, ∼50 nm wide, microns-long nanocrystals, bundled either into 5-μm-wide rods or their space-filling interrod. The orientation of enamel crystals, however, is poorly understood. Here we show that the crystalline c-axes are homogenously oriented in interrod crystals across most of the enamel layer thickness. Within each rod crystals are not co-oriented with one another or with the long axis of the rod, as previously assumed: the c-axes of adjacent nanocrystals are most frequently mis-oriented by 1°–30°, and this orientation within each rod gradually changes, with an overall angle spread that is never zero, but varies between 30°–90° within one rod. Molecular dynamics simulations demonstrate that the observed mis-orientations of adjacent crystals induce crack deflection. This toughening mechanism contributes to the unique resilience of enamel, which lasts a lifetime under extreme physical and chemical challenges.

Sign in / Sign up

Export Citation Format

Share Document