633 research outputs found
Parametric study of lunar landing techniques using a predetermined thrust orientation
Parametric study of variation in trajectory parameters for predetermined thrust orientation angle to perform lunar descent from parking orbi
Motion of the sub-satellite point for 24-hour orbits
Subsatellite path for 24-hour orbits affected by changes in eccentricity, inclination, and argument of perigee - orbital path of syncom i
Pengaruh Model Numbered Head Together Dalam Pembelajaran IPS Terhadap Hasil Belajar Siswa Mis Bawari
The problem of this research is "Is there any influence of using Numbered Head Together model in IPS learning toward student learning result class V Mis Bawari Pontianak City?". The research method used is experimental method. The form of research is quasi experiment (Quasi Experimental Design) with the experimental design Nonequivalent Control Group Design. The population and its sample are VA class students and VB Mis Bawari Pontianak City which consists of 28 students of VA class (control class) and 28 students of VB class (experimental class). The research instrument used in the form of test questions in the form of multiple choice with the number of 60 questions. The average post test class test results were 76.90 and the average post test class test result was 66.90. The result of t test is obtained tcount 3,8553 and ttable α = 5% (with dk = 28 + 28 - 2 = 54) equal to 1.6619, which means tcount (3.8553)> ttable (1.6619), then Ha be accepted. This is the influence of the use of Numbered Head Together model in the social studies learning on the results of students of class V Mis Bawari Pontianak City. Calculation effect size (ES), obtained ES of 1.03 (high criteria). This means that the use of Numbered Head Together model gives a high influence on the students' IPS learning outcomes in class V Mis Bawari Pontianak City
Working with simple machines
A set of examples is provided that illustrate the use of work as applied to
simple machines. The ramp, pulley, lever and hydraulic press are common
experiences in the life of a student and their theoretical analysis therefore
makes the abstract concept of work more real. The mechanical advantage of each
of these systems is also discussed so that students can evaluate their
usefulness as machines.Comment: 9 pages, 4 figure
Understanding the interactions of cellulose fibres and deep eutectic solvent of choline chloride and urea
This is the author accepted manuscript. The final version is available from Springer Verlag via the DOI in this record.A deep eutectic solvent composed of choline chloride (ChCl) and urea has been recently introduced as a promising cellulose compatible medium that enables e.g. fibre spinning. This paper clarifies the influence of such a solvent system on the structure and chemical composition of the cellulosic pulp fibres. Special emphasis was placed on the probable alterations of the chemical composition due to the dissolution of the fibre components and/or due to the chemical derivatisation taking place during the DES treatment. Possible changes in fibre morphology were studied with atomic force microscopy and scanning electron microscopy. Chemical compositions of pulp fibres were determined from the carbohydrate content, and by analysing the elemental content. Detailed structural characterisation of the fibres was carried out using spectroscopic methods; namely X-Ray Photoelectron Spectroscopy, solid state Nuclear Magnetic Resonance and Raman Spectroscopy. No changes with respect to fibre morphology were revealed and negligible changes in the carbohydrate composition were noted. The most significant change was related to the nitrogen content of the pulp after the DES treatment. Comprehensive examination using spectroscopic methods revealed that the nitrogen originated from strongly bound ChCl residuals that could not be removed with a mild ethanol washing procedure. According to Raman spectroscopic data and methylene blue adsorption tests, the cationic groups of ChCl seems to be attached to the anionic groups of pulp by electrostatic forces. These findings will facilitate the efficient utilisation of DES as a cellulose compatible medium without significantly affecting the native fibre structure.The authors acknowledge the Finnish Funding Agency for Innovation (TEKES) for funding the work via Design Driven Value Chains in the World of Cellulose 2.0 project. The Academy of Finland (Project ID 300367) is acknowledged for enabling the research mobility of T.T. to the University of Exeter, UK. Unto Tapper (VTT) is thanked for the SEM imaging, Atte Mikkelson, Ritva Heinonen and Marita Ikonen (VTT) for the chemical analysis and Robertus Nugroho (Aalto University) for the AFM imaging
Structure of Be probed via secondary beam reactions
The low-lying level structure of the unbound neutron-rich nucleus Be
has been investigated via breakup on a carbon target of secondary beams of
B at 35 MeV/nucleon. The coincident detection of the beam velocity
Be fragments and neutrons permitted the invariant mass of the
Be+ and Be++ systems to be reconstructed. In the case of
the breakup of B, a very narrow structure at threshold was observed in
the Be+ channel. Contrary to earlier stable beam fragmentation
studies which identified this as a strongly interacting -wave virtual state
in Be, analysis here of the Be++ events demonstrated that
this was an artifact resulting from the sequential-decay of the
Be(2) state. Single-proton removal from B was found to
populate a broad low-lying structure some 0.70 MeV above the neutron-decay
threshold in addition to a less prominent feature at around 2.4 MeV. Based on
the selectivity of the reaction and a comparison with (0-3)
shell-model calculations, the low-lying structure is concluded to most probably
arise from closely spaced J=1/2 and 5/2 resonances
(E=0.400.03 and 0.85 MeV), whilst the broad
higher-lying feature is a second 5/2 level (E=2.350.14 MeV). Taken
in conjunction with earlier studies, it would appear that the lowest 1/2
and 1/2 levels lie relatively close together below 1 MeV.Comment: 14 pages, 13 figures, 2 tables. Accepted for publication in Physical
Review
Direct reaction measurements with a 132Sn radioactive ion beam
The (d,p) neutron transfer and (d,d) elastic scattering reactions were
measured in inverse kinematics using a radioactive ion beam of 132Sn at 630
MeV. The elastic scattering data were taken in a region where Rutherford
scattering dominated the reaction, and nuclear effects account for less than 8%
of the cross section. The magnitude of the nuclear effects was found to be
independent of the optical potential used, allowing the transfer data to be
normalized in a reliable manner. The neutron-transfer reaction populated a
previously unmeasured state at 1363 keV, which is most likely the
single-particle 3p1/2 state expected above the N=82 shell closure. The data
were analyzed using finite range adiabatic wave calculations and the results
compared with the previous analysis using the distorted wave Born
approximation. Angular distributions for the ground and first excited states
are consistent with the previous tentative spin and parity assignments.
Spectroscopic factors extracted from the differential cross sections are
similar to those found for the one neutron states beyond the benchmark
doubly-magic nucleus 208Pb.Comment: 22 pages, 7 figure
Biodegradable nanomats produced by electrospinning : expanding multifunctionality and potential for tissue engineering
With increasing interest in nanotechnology, development of nanofibers (n-fibers) by using the
technique of electrospinning is gaining new momentum. Among important potential applications of
n-fiber-based structures, scaffolds for tissue-engineering represent an advancing front. Nanoscaffolds
(n-scaffolds) are closer to natural extracellular matrix (ECM) and its nanoscale fibrous structure.
Although the technique of electrospinning is relatively old, various improvements have been
made in the last decades to explore the spinning of submicron fibers from biodegradable polymers
and to develop also multifunctional drug-releasing and bioactive scaffolds. Various factors can
affect the properties of resulting nanostructures that can be classified into three main categories,
namely: (1) Substrate related, (2) Apparatus related, and (3) Environment related factors. Developed
n-scaffolds were tested for their cytocompatibility using different cell models and were seeded
with cells for to develop tissue engineering constructs. Most importantly, studies have looked at the
potential of using n-scaffolds for the development of blood vessels. There is a large area ahead
for further applications and development of the field. For instance, multifunctional scaffolds that
can be used as controlled delivery system do have a potential and have yet to be investigated for
engineering of various tissues. So far, in vivo data on n-scaffolds are scarce, but in future reports
are expected to emerge. With the convergence of the fields of nanotechnology, drug release and
tissue engineering, new solutions could be found for the current limitations of tissue engineering
scaffolds, which may enhance their functionality upon in vivo implantation. In this paper electrospinning
process, factors affecting it, used polymers, developed n-scaffolds and their characterization
are reviewed with focus on application in tissue engineering
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