Number of Particles Per Unit Volume

Stereology ◽  
1967 ◽  
pp. 199-210 ◽  
Author(s):  
Herbert Haug
Keyword(s):  
Unit Volume ◽  
Number Of Particles

scholarly journals Remarks on the Size Distribution of Colliding and Fragmenting Particles

1971 ◽  
Vol 12 ◽  
pp. 297-303
Author(s):  
Lothar W. Bandermann
Keyword(s):  
Finite Number ◽  
Size Distribution ◽  
Unit Volume ◽  
Interplanetary Dust ◽  
Fixed Volume ◽  
Two Bodies ◽  
Mass Interval ◽  
Number Of Particles ◽  
The Way

This paper is concerned with some aspects of determining the evolution of the size distribution of a finite number of mutually colliding and fragmenting particles such as the asteroids or interplanetary dust. If n(m, t) is the number of particles per unit volume per mass interval at time t, then n = dn/dt is the rate at which that number changes with time. This rate can be calculated if the laws are known according to which the colliding bodies erode one another and fragment and if the influence of collisions on the motion of the particles is known. To reduce the complexity of the problem, one assumes that the speed of approach between the bodies is always the same vcoll and that they, as well as the debris, occupy a fixed volume (“particles in a box”). Only collisions between two bodies are considered, and the way in which erosion and fragmentation occurs at a given value of vcoll depends only on their masses. The particles are assumed to be spherical.

The properties of a perfect Einstein-Bose gas at low temperatures

1938 ◽  
Vol 34 (4) ◽  
pp. 573-576 ◽  
Author(s):  
R. H. Fowler ◽  
H. Jones
Keyword(s):  
Condensed Phase ◽  
Low Temperatures ◽  
Unit Volume ◽  
Bose Gas ◽  
The Other ◽  
Perfect Gas ◽  
Recent Letter ◽  
Bose Statistics ◽  
Image Position ◽  
Number Of Particles

In a recent letter to Nature F. London(3) has called attention to a discontinuity in the derivative dCV/dT of the specific heat with respect to temperature which arises in a perfect Einstein-Bose gas at low temperatures. When discussing the properties of a perfect gas satisfying the Bose statistics, Einstein(1) remarked that at low temperatures something resembling a condensed phase should appear. The temperature at which this condensation should begin is given by the equationwhere n is the number of particles of mass m per unit volume and the other symbols have their usual significance.

scholarly journals HASIL PENGUKURAN PARTIKEL ASAP GROUND PERTICLES GENERATOR (GPG) DI LAB TMC PUSPIPTEK SERPONG PADA 11 APRIL 2013

2013 ◽  
Vol 14 (1) ◽  
pp. 59
Author(s):  
R. Djoko Goenawan ◽  
Untung Haryanto ◽  
Pitoyo Sarwono Sudibyo ◽  
Bambang Asmoro ◽  
Pamuji Pamuji
Keyword(s):  
Concentration Distribution ◽  
Unit Volume ◽  
Measurement Tool ◽  
Smoke Particles ◽  
Tail Distribution ◽  
Large Particles ◽  
Long Time ◽  
Distribution Right ◽  
Sediment Particles ◽  
Number Of Particles

ABSTRAK  Telah dilakukan pengukuran distribusi dan konsentrasi asap partikel dari hasil penyalaan GPG yang dilakukan di Lap TMC - Puspiptek Serpong. Alat yang digunakan dalam pengukuran baik besar, distribusi dan konsentrasi partikel adalah menggunakan LightHouse (LH) yang bisa menampilkan secara langsung dalam layar monitor alat tersebut. Yang secara langsung terbaca dalam monitoring LH adalah besar partikel dan jumlah partikel per satuan volume (m3). Kisaran alat pengukur partikel LH bisa mengukur terkecil 0.3 mikron hingga 5 mikron dengan rincian 0.3, 0.5, 1.0, 2.5, dan 5 mikron. Light House (LH) adalah satu satunya alat yang biasa digunakan untuk pengukuran udara dan lingkungan dari Laboratorium Aerosol, PTKMR BATAN. Telah dilakukan pengukuran partikel dari asap GPG (Ground Particles Generator) sebanyak 21 kali sampling. Sekali pegambilan sampling asap diperlukan waktu sebanyak 5 menit dan pengukuran udara dalam wadah sampling tersebut juga diperlukan waktu sekitar 5 menit. Selain pengukuran dengan menggunakan LH, juga dilakukan pengukuran dengan menggunakan Impaktor Kaskade Type Anderson dengan 12 tingkat yang memungkinkan pengukuran dari 0.1 mikron hingga 9 mikron. Waktu yang diperlukan cukup lama, yaitu antara pukul 13.15 hingga 18.15 WIB yaitu 5 jam. Impaktor tidak bisa langsung terbaca hasil pengukuran partikelnya namun harus di proses kemudian di kondiskan serta dilakukan penimbangan partikel yang mengendap di setiap tingkatan, sehingga bisa diketahui distribusi partikel tersebut setiap tingkat dari 0.1 mikron hingga partikel terbesar yaitu 9 mikron. Hasil sementara dari pengukuran menggunakan LH dari sebanyak 21 sampel adalah untuk partikel 0.3 mikron memiliki jumlah partikel terbesar mencapai 495.466.815/m3 atau 495 partikel/cm3 asap dan terkecil sebanyak  51.767.763/m3 atau 52 partikel/cm3 asap. Sementara, untuk partikel yang terukur 0.5 mikron terbanyak mencapai 8.969.923/m3 atau 9 partikel/cm3 asap dan terkecil 84.755.200 partikel/cm3 atau 85 partikel/cm3. Sedangkan, partikel yang terukur 1.0, 2.5 dan 5.0 mikron di LH tidak terpantau atau tidak ada sama sekali alias Nol (skala 1 cm3). Tampak puncak distribusinya diperkirakan kurang dari 0.3 mikron (antara 0.1 – 0.05 mikron), sebagai “tail” kanan distribusi (jika dianggap normal) adalah 0.5 mikron. Perkiraan tersebut akan di buktikan dengan menggunakan Impaktor yang bisa mengukur partikel terkecil 0.1 mikron.    ABSTRACT  Measurement of Concentration Distribution and smoke particles from the ignition GPG conducted in TMC-Lab Puspiptek Serpong. Measurement tool used in both large, the distribution and concentration of particles is using Light-House (LH) which can display directly in the device monitor screen which is directly readable in monitoring large particles and LH is the number of particles per unit volume (m3). LH range of gauges can measure the smallest particles 0.3 microns to 5 microns with the details 0.3, 0.5, 1.0, 2.5 and 5 microns. Light House (LH) is the only tool used to measure air and environment of the Aerosol Laboratory, PTKMR BATAN in Jakarta. Have performed measurements of the smoke particles GPG (Ground Particles Generator) as much as 21 times the sampling. Once pegambilan sampling smoke take as many as 5 minutes and air measurements in the sampling container also takes about 5 minutes as well. In addition to measurements by using LH, also be measured by using the cascade Impaktor Type Anderson with 12 levels that allow measurement of 0.1 microns to 9 microns. It takes quite a long time, which is between 13:15 to 18:15 hrs ie 5 hour. Impaktor can not directly read the results of measurements of the particles but must be in process later in kondiskan and sediment particles weighing is done at every level, so they can know the distribution of particles of 0.1 microns each level until the largest particles is 9 microns. Interim results of measurements using as many as 21 samples of LH is for 0.3 micron particles have the greatest number of particles reaching 495 partikel/cm3 495.466.815/m3 or as much smoke and the smallest 52 partikel/cm3 51.767.763/m3 or smoke. While, for the measured particles 0.5 microns or 9 the highest reaches 8.969.923/m3 partikel/cm3 smoke and smallest partikel/m3 84,755,200 or 85 partikel/cm3. Whereas, particles measured 1.0, 2.5 and 5.0 microns in LH is not monitored or none at all, aka Zero. Looks peak distribution estimated to be less than 0.1 microns, as the "tail" distribution right (if it is considered normal) is 0.5 microns. The estimate will be proved by using Impaktor that can measure the smallest particles of 0.1 microns.

Scattering Cross Sections in Electron Microscopy and Microanalysis

1999 ◽  
Vol 5 (S2) ◽  
pp. 672-673
Author(s):  
Peter Rez
Keyword(s):  
Electron Microscopy ◽  
Cross Section ◽  
Cross Sections ◽  
Unit Volume ◽  
Unit Area ◽  
Incident Beam ◽  
Scattering Cross Section ◽  
Scattering Cross ◽  
Scattering Cross Sections ◽  
Number Of Particles

In all scattering experiments some measure is need of the strength of the scattering interaction. The scattering cross section, which has dimensions of area, is a quantity that can be defined for any scattering interactions, irrespective of the nature of the scatterer, or the particle or radiation being scattered. To define a scattering cross section, refer to the geometry of Figure 1. If I0 is the incident number of particles, Is the number of particles scattered through an angle θ with an energy loss ΔE, N is the number of scatterers/ unit volume and t is the thickness of the specimen (or length of the scattering region) then where σ(θ ,ΔE) is the scattering cross section. The product N t represents the number of scatterers per unit area as seen by the incident beamIn electron microscopy all scattering arises from the Coulomb interaction between the incident electron and the electrons or nuclei or the atoms in the specimen.

INITIAL VALUE PROBLEMS IN λφ4 FIELD THEORY IN A BACKGROUND GRAVITATIONAL FIELD

1987 ◽  
Vol 02 (09) ◽  
pp. 635-644 ◽  
Author(s):  
FRED COOPER ◽  
EMIL MOTTOLA
Keyword(s):  
Field Theory ◽  
Initial Value Problems ◽  
Unit Volume ◽  
Evolution Equations ◽  
Initial Value ◽  
Initial State ◽  
Simple Method ◽  
Large N ◽  
Number Of Particles ◽  
Classical Background

We derive the time evolution equations appropriate to initial value problems in λ(φαφα)2 field theory at large N interacting with a classical background spatially flat R.W. metric. We determine from physical considerations the renormalization of the mass, the self coupling and the coupling to the scalar curvature. A simple method is given to arrive at finite differential equations suitable for numerical integration forward in time. We find that for the equations to be finite, the ultraviolet properties of the initial state are constrained by the requirement that the initial state contains a finite average number of particles and/or correlated pairs per unit volume.

Stereo Electron Microscopy Applied to High Resolution Freeze-Etch Replicas

1970 ◽  
Vol 28 ◽  
pp. 306-307
Author(s):  
L. Andrew Staehelin
Keyword(s):  
Electron Microscopy ◽  
Plastic Deformation ◽  
High Resolution ◽  
Smooth Surfaces ◽  
Small Particles ◽  
Membrane Surfaces ◽  
Wide Acceptance ◽  
New Information ◽  
Number Of Particles ◽  
Small Holes

Freeze-etched membranes usually appear as relatively smooth surfaces covered with numerous small particles and a few small holes (Fig. 1). In 1966 Branton (1“) suggested that these surfaces represent split inner mem¬brane faces and not true external membrane surfaces. His theory has now gained wide acceptance partly due to new information obtained from double replicas of freeze-cleaved specimens (2,3) and from freeze-etch experi¬ments with surface labeled membranes (4). While theses studies have fur¬ther substantiated the basic idea of membrane splitting and have shown clearly which membrane faces are complementary to each other, they have left the question open, why the replicated membrane faces usually exhibit con¬siderably fewer holes than particles. According to Branton's theory the number of holes should on the average equal the number of particles. The absence of these holes can be explained in either of two ways: a) it is possible that no holes are formed during the cleaving process e.g. due to plastic deformation (5); b) holes may arise during the cleaving process but remain undetected because of inadequate replication and microscope techniques.

Quantitative energy-filtered tem imaging of interfaces

1996 ◽  
Vol 54 ◽  
pp. 542-543 ◽  
Author(s):  
J. Bentley ◽  
E. A. Kenik ◽  
K. Siangchaew ◽  
M. Libera
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Unit Volume ◽  
Core Loss ◽  
Mean Free Path ◽  
Slit Width ◽  
Elemental Mapping ◽  
Low Loss ◽  
Transmission Electron ◽  
Inelastic Mean Free Path

Quantitative elemental mapping by inner shell core-loss energy-filtered transmission electron microscopy (TEM) with a Gatan Imaging Filter (GIF) interfaced to a Philips CM30 TEM operated with a LaB6 filament at 300 kV has been applied to interfaces in a range of materials. Typically, 15s exposures, slit width Δ = 30 eV, TEM magnifications ∼2000 to 5000×, and probe currents ≥200 nA, were used. Net core-loss maps were produced by AE−r background extrapolation from two pre-edge windows. Zero-loss I0 (Δ ≈ 5 eV) and “total” intensity IT (unfiltered, no slit) images were used to produce maps of t/λ = ln(IT/I0), where λ is the total inelastic mean free path. Core-loss images were corrected for diffraction contrast by normalization with low-loss images recorded with the same slit width, and for changes in thickness by normalization with t/λ, maps. Such corrected images have intensities proportional to the concentration in atoms per unit volume. Jump-ratio images (post-edge divided by pre-edge) were also produced. Spectrum lines across planar interfaces were recorded with TEM illumination by operating the GIF in the spectroscopy mode with an area-selecting slit oriented normal to the energy-dispersion direction. Planar interfaces were oriented normal to the area-selecting slit with a specimen rotation holder.

Angular Calibration of Ribosomal Subuntts in Factor Space

1990 ◽  
Vol 48 (1) ◽  
pp. 462-463
Author(s):  
Minakhi Pujari ◽  
Joachim Frank
Keyword(s):  
Three Dimensional ◽  
Carbon Layer ◽  
Uranyl Acetate ◽  
Particle Analysis ◽  
Factor Space ◽  
Multivariate Statistical ◽  
Ribosomal Subunits ◽  
Layer Method ◽  
Dimensional Reconstruction ◽  
Number Of Particles

In single-particle analysis of macromolecule images with the electron microscope, variations of projections are often observed that can be attributed to the changes of the particle’s orientation on the specimen grid (“rocking”). In the multivariate statistical analysis (MSA) of such projections, a single factor is often found that expresses a large portion of these variations. Successful angle calibration of this “rocking factor” would mean that correct angles can be assigned to a large number of particles, thus facilitating three-dimensional reconstruction.In a study to explore angle calibration in factor space, we used 40S ribosomal subunits, which are known to rock around an axis approximately coincident with their long axis. We analyzed micrographs of a field of these particles, taken with 20° tilt and without tilt, using the standard methods of alignment and MSA. The specimen was prepared with the double carbon-layer method, using uranyl acetate for negative staining. In the MSA analysis, the untilted-particle projections were used as active, the tilted-particle projections as inactive objects. Upon tilting, those particles whose rocking axes are parallel to the tilt axis will change their appearance in the same way as under the influence of rocking. Therefore, each vector, in factor space, joining a tilted and untilted projection of the same particle can be regarded as a local 20-degree calibration bar.

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