scholarly journals Glass Fracture during Micro-Scratching

Surfaces ◽  
2020 ◽  
Vol 3 (2) ◽  
pp. 211-224
Author(s):  
Islam Zakiev ◽  
George A. Gogotsi ◽  
Michael Storchak ◽  
Vadim Zakiev
Keyword(s):  
Statistical Method ◽  
Glass Surface ◽  
Applied Load ◽  
Constant Load ◽  
Berkovich Indenter ◽  
Surface Fracture ◽  
Glass Fracture ◽  
Long Time ◽  
Breaking Mechanism ◽  
Established Fact

The regularity of glass surface fracture and resistance to destruction were investigated by the methods of progressive and static microscratching with the Berkovich indenter. The research hardware was the original nanoindentation/microscratching devices and a non-contact interference profilometer for studying the morphology of the formed microscratches. The regularities of the fracture stages and the cracks growth along the microscratch were established depending on the indenter applied load. Based on analysis of the microcracks profile formed at various loads on the indenter immediately after the process of applying these scratches and after several hours of rest, it was found that the process of crack propagation along the scratch continues for a long time. Taking into account this established fact, a discrete-statistical method of the cracks formation for a long time is proposed. In accordance with this method, scratching is carried out with a constant load on short and separated tracks. The load on the indenter in each track increases discretely with a certain step. The influence of the medium on the scratching process is analyzed. The breaking mechanism in the glasses scratching process is formulated as the load on the indenter increases, and a model of the glass fracture stages is proposed.

scholarly journals Rheometer enabled study of cartilage frequency-dependent properties

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Stefano Perni ◽  
Polina Prokopovich
Keyword(s):  
Applied Load ◽  
Cost Effective ◽  
Constant Load ◽  
Hydraulic Permeability ◽  
Frequency Dependent ◽  
Shear Moduli ◽  
Tissue Replacement ◽  
Cost Effective Approach ◽  
The Impact

AbstractDespite the well-established dependence of cartilage mechanical properties on the frequency of the applied load, most research in the field is carried out in either load-free or constant load conditions because of the complexity of the equipment required for the determination of time-dependent properties. These simpler analyses provide a limited representation of cartilage properties thus greatly reducing the impact of the information gathered hindering the understanding of the mechanisms involved in this tissue replacement, development and pathology. More complex techniques could represent better investigative methods, but their uptake in cartilage research is limited by the highly specialised training required and cost of the equipment. There is, therefore, a clear need for alternative experimental approaches to cartilage testing to be deployed in research and clinical settings using more user-friendly and financial accessible devices. Frequency dependent material properties can be determined through rheometry that is an easy to use requiring a relatively inexpensive device; we present how a commercial rheometer can be adapted to determine the viscoelastic properties of articular cartilage. Frequency-sweep tests were run at various applied normal loads on immature, mature and trypsinased (as model of osteoarthritis) cartilage samples to determine the dynamic shear moduli (G*, G′ G″) of the tissues. Moduli increased with increasing frequency and applied load; mature cartilage had generally the highest moduli and GAG depleted samples the lowest. Hydraulic permeability (KH) was estimated from the rheological data and decreased with applied load; GAG depleted cartilage exhibited higher hydraulic permeability than either immature or mature tissues. The rheometer-based methodology developed was validated by the close comparison of the rheometer-obtained cartilage characteristics (G*, G′, G″, KH) with results obtained with more complex testing techniques available in literature. Rheometry is relatively simpler and does not require highly capital intensive machinery and staff training is more accessible; thus the use of a rheometer would represent a cost-effective approach for the determination of frequency-dependent properties of cartilage for more comprehensive and impactful results for both healthcare professional and R&D.

scholarly journals The lunar diurnal variation of atmospheric temperature at Batavia, 1866-1928

1932 ◽  
Vol 137 (831) ◽  
pp. 1-24 ◽  
Keyword(s):  
Heat Flow ◽  
Temperature Variation ◽  
Wave Length ◽  
Barometric Pressure ◽  
Atmospheric Temperature ◽  
Vertical Flow ◽  
Tidal Changes ◽  
Long Time ◽  
Semidiurnal Variation ◽  
Established Fact

The existence of a lunar tide in the earth’s atmosphere is now a well-established fact. It is indicated by a lunar semidiurnal variation of barometric pressure, found at every station for which the necessary reductions have been made. Now a variation of pressure in a gas is in general accompanied by a variation of temperature. The amount of this variation depends on the rate at which heat can flow in the gas, from a region of compression to one of rarefaction, or from the earth or ocean to or from the gas. The maximum variation of temperature corresponds to adiabatic changes of pressure, while if the heat flow can be very rapid, the temperature variation may be reduced almost to zero, corresponding to isothermal changes of pressure. I have shown that the lunar tidal changes of pressure will be almost adiabatic so far as concerns heat flow in the gas , between regions of compression and of rarefaction. The long time available for equalisation of temperature, viz., a quarter of a lunar day, or about 6 hours, is in fact ineffective because of the long wave-length of the tide, the distance between the regions of highest or lowest pressure in any latitude being a quarter of the circumference of the circle of latitude. The temperature variation might be reduced below the adiabatic value if vertical flow of heat, between the air and the ground or ocean, is sufficiently rapid. This point will be discussed in another paper; the conclusion reached is that the vertical flow of heat is unlikely to be important over the land . Hence a temperature variation approaching the adiabatic value is likely to be associated with the lunar atmospheric tide at a land station.

scholarly journals Summary of JD 9 Supernovae: past, present, and future

2006 ◽  
Vol 2 (14) ◽  
pp. 317-318
Author(s):  
Virginia L. Trimble
Keyword(s):  
Statistical Method ◽  
Variable Stars ◽  
Hard Work ◽  
Long Time

SN 1006 was the first (and for a very long time the only) event to be caught before peak light. A passage which, according to Stephenson, does not actually pertain to the SN, nevertheless makes clear that, even then, a hypothesis was more likely to be accepted if it made a prediction later verified, though the prediction was that something bad would happen to Emperor Sanjo In. The hypothesis was that the star was not new, but related to behavior of existing stars in Qichen Jianjun. According to the poster by P.J. Boner, Kepler made the opposite choice for ‘his’ SN, calling it a genuinely new star formed out of the ether, rather than mere change in appearance. Indeed the distinction between true novae and variable stars was not drawn correctly until Hevelius's 1662 study of Mira, after Tycho had shown that his event (and the comet of 1577) were more distant than our Moon, a point disputed by many of his contemporaries, but accepted by Galileo, who applied a very early statistical method to many different observations of SN 1572. Tycho's main advantages were better equipment and hard work, again not so different from present conditions.

Space, Society, Religion: A Short Retrospective and Prospective Note

2016 ◽  
Author(s):  
François de Polignac
Keyword(s):  
Spatial Distribution ◽  
Social Life ◽  
Historical Geography ◽  
Fundamental Aspect ◽  
General Conception ◽  
Human And Social Sciences ◽  
Classical Studies ◽  
Long Time ◽  
Established Fact ◽  
Epigraphic Evidence

It is now a well-established fact in the human and social sciences that the study of the spatial distribution of social life, including religion, is one of the best accesses to the analysis and understanding of societies. But it has not always been so. For quite a long time, in Classical studies, the only approach to space was traditional ‘historical geography’, the scope of which was primarily to identify the places mentioned in the ancient sources or known through archaeological or epigraphic evidence. This was and remains an important contribution to the study of ancient societies. But in these works the study of topography does not sustain a general conception of space as such and as a fundamental aspect of social life; and in fact, space as a category of study was not formalised as such.

scholarly journals Crack formation in soda-lime glass after high-power ion beam irradiation

2018 ◽  
Vol 36 (3) ◽  
pp. 359-362
Author(s):  
Vladimir S. Kovivchak ◽  
Tatyana V. Panova
Keyword(s):  
High Power ◽  
Glass Surface ◽  
Ion Beam ◽  
Soda Lime ◽  
Soda Lime Glass ◽  
Nanosecond Duration ◽  
Air Atmosphere ◽  
Glass Fracture ◽  
Current Densities ◽  
Heated Glass

AbstractThe fractures of a soda-lime glass surface layer were investigated under irradiation by a high-power ion beam of nanosecond duration with different current densities. Two kinds of cracks (perpendicular and approximately parallel irradiated surfaces) have been identified. It is defined that cracks approximately parallel to the surface are localized at a depth of 10 ± 2 µm from the irradiated glass surface after one-time irradiation with a current density of 100 A/cm2. The formation of these cracks was detected within ~170 h after the end of irradiation when irradiated samples were under an air atmosphere. In a vacuum, the growth of these cracks was insignificant. It is shown that irradiation of heated glass or heating of glass started no later than 2–3 min after irradiation can suppress or substantially reduce surface fracture of glass. The possible mechanisms of glass fracture were discussed.

Construction Organization Optimization for Subgrade Engineering in Tropical Rainy Regions

2013 ◽  
Vol 353-356 ◽  
pp. 795-801
Author(s):  
Bo Yang ◽  
Rui Zhang ◽  
Shu Ping Luo ◽  
Ping He ◽  
Yu Feng Qiu
Keyword(s):  
Statistical Method ◽  
Correlation Coefficient ◽  
Random Variable ◽  
Exponential Relationship ◽  
Engineering Construction ◽  
Construction Period ◽  
Statistical Function ◽  
Long Time ◽  
Grade Division ◽  
Construction Organization

According to the highway subgrade engineering construction period serious delaying by rainy climate for a long time in the tropical rainy regions. The key process of the subgrade construction affected by climate is roadbed filling turning. Binding the law of rainy, Considered the continuous available period for filling turning as a random variable to analyze the correlation with its frequency, established the regression formula, the values of correlation coefficient is more than 0.95, shows that the continuous available period for filling turning presents good exponential relationship, A new statistical method of continuous available period for filling turning called selecting time construction concept was put forward. According the feasible probability of the continuous available period for filling turning, put forward a new grade division method for roadbed filling. Optimized the construction organization of the subgrade engineering by the statistical function of continuous available period for roadbed filling turning, and proved its reliability and achievability. Demonstration and reference were provided for the highway construction and local standardization in southern rainy regions.

Experimental Study of a Dry Sliding Wear for a Different Materials Using a Pin-on-Disk Apparatus

2021 ◽  
Vol 1021 ◽  
pp. 78-86
Author(s):  
Hussein M. Ali ◽  
Qussay Y. Hamid ◽  
Thaer F.A. Al-Sultan
Keyword(s):  
Stainless Steel ◽  
Wear Rate ◽  
Sliding Wear ◽  
Applied Load ◽  
Constant Load ◽  
Dry Sliding Wear ◽  
Dry Sliding ◽  
Sliding Speed ◽  
Stainless Steel 304 ◽  
Pin On Disk

In the present work, an experimental investigation has been made of a dry sliding wear rate for aluminum, aluminum alloy (Al-Fe-V-Si), bronze, stainless steel 304 and structural steel ASTM A36, using a pin-on-disk apparatus under the effect of sliding speed and time at constant load. The materials were tested on two types of abrasive surfaces with a grit surface of 24 and 36. The applied load was equal to 2500 grams and the same load was used for all of the pins that were tested. The relative wear was indicated by the loss in length and loss in mass. The results show that the wear rate will directly proportional with sliding speed and time, and the stainless steel has less wear rate than the other materials.

The Power of Movies and a Method to Study It

2021 ◽  
pp. 1-19
Author(s):  
James E. Cutting
Keyword(s):  
Statistical Method ◽  
Sustained Attention ◽  
Human Mind ◽  
Past Century ◽  
Case Study Method ◽  
Popular Cinema ◽  
Long Time ◽  
Emotional Commitment ◽  
Psychological Dimensions

Popular cinema has been around a long time; much has remained constant, much has changed. This chapter broaches some of the changes in and around movies during the past century. These changes have been made to boost viewers’ engagement, which depends on at least four psychological dimensions: their sustained attention, their understanding of the narrative, their emotional commitment, and their feeling of presence in the story. The chapter also provides an overview of two methods of academic study in the sciences and humanities—the case study method and the wider sampling, statistical method. It then lays out the case for studying many movies as a sampled group, but it also knowledges pitfalls. Nonetheless, study of many movies has a great number of things to offer, for each of the movies and for understanding the nature of the human mind.

Toward a probabilistic biology

2014 ◽  
Vol 24 (3) ◽  
Author(s):  
JEAN-JACQUES KUPIEC
Keyword(s):  
Gene Expression ◽  
Probabilistic Models ◽  
Probabilistic Approach ◽  
Short Paper ◽  
Cell Physiology ◽  
New Techniques ◽  
Cellular Processes ◽  
Long Time ◽  
Established Fact ◽  
Epistemological Obstacle

Stochastic gene expression (SGE) is now considered to be an established fact and has become an important subject of research (Viñuelas et al. 2012). During the last decade, the availability of new techniques has made possible the production of more precise and more spectacular data showing the extensive variability in gene expression occurring between individual cells. However, evidence supporting probabilistic models of cell behaviour and gene expression has been available for quite a long time – for example, see the reviews in Laforge et al. (2005) and Golubev (2010). It should be noted that the first model of stochastic cell differentiation was proposed in 1964 (Till et al. 1964), which is almost at the same time as the genetic programming theory (Jacob and Monod 1961), which is deterministic in nature. One can thus wonder why the determinist view of biology has remained dominant for such a long time, and what makes a probabilistic view more acceptable nowadays? In this short paper, I will briefly argue that there is a strong epistemological obstacle to the acceptance of probabilism in biology, and that even today SGE is not integrated into a fully probabilistic approach of cellular processes, but rather into a concept that I call ‘determinism with noise’. I will argue that a new fully probabilistic theoretical framework is needed to truly integrate the stochastic aspects of cell physiology.

200kv superconducting cryo electron microscope

1987 ◽  
Vol 45 ◽  
pp. 642-643
Author(s):  
M. Iwatsuki ◽  
Y. Kokubo ◽  
Y. Harada ◽  
J. Lehman
Keyword(s):  
Electron Microscope ◽  
Structure Analysis ◽  
Organic Materials ◽  
Strong Interactions ◽  
Specimen Preparation ◽  
Great Effort ◽  
Electron Microscopic ◽  
Crystal Fields ◽  
Special Skill ◽  
Long Time

In recent years, the electron microscope has been significantly improved in resolution and we can obtain routinely atomic-level high resolution images without any special skill. With this improvement, the structure analysis of organic materials has become one of the interesting targets in the biological and polymer crystal fields.Up to now, X-ray structure analysis has been mainly used for such materials. With this method, however, great effort and a long time are required for specimen preparation because of the need for larger crystals. This method can analyze average crystal structure but is insufficient for interpreting it on the atomic or molecular level. The electron microscopic method for organic materials has not only the advantage of specimen preparation but also the capability of providing various information from extremely small specimen regions, using strong interactions between electrons and the substance. On the other hand, however, this strong interaction has a big disadvantage in high radiation damage.

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