EFFECT OF MEAN PORE SIZE ON THE LOW-TEMPERATURE ADSORPTION OF NITROGEN ON ALUMINA

1960 ◽  
Vol 38 (6) ◽  
pp. 783-786 ◽  
Author(s):  
J. L. Blumenthal ◽  
S. Sourirajan ◽  
Ken Nobe
Keyword(s):  
Low Temperature ◽  
Pore Size ◽  
Pore Radius ◽  
Capillary Condensation ◽  
Pressure Ratio ◽  
Relative Pressure ◽  
The Third ◽  
Two Samples ◽  
Adsorption Of Nitrogen ◽  
The Mean

The effect of mean pore size on the low-temperature adsorption of nitrogen on two samples of alumina has been studied. The mean pore radius of one sample of alumina was 37 Å, and that of the other was 3100 Å. The two adsorption isotherms at −195.8 °C have been plotted in terms of the volume of gas adsorbed per square meter of surface area vs. relative pressure ratio. The data have been found to fall into three distinct regions. In the first region extending up to the relative pressure ratio of 0.3, the two isotherms are nearly identical. In the second region extending from the relative pressure ratio of 0.3 to 0.75, the isotherm for the small mean pore size alumina lies above that for the large mean pore size sample. In the third region extending from the relative pressure ratio of 0.75 up to saturation, the isotherm for the small mean pore size sample tends to level off whereas that for the large mean pore size sample rises rapidly with increase in the relative pressure ratio. The above experimental observations have been explained on the basis of capillary condensation.

scholarly journals Characterization and Catalytic Behaviour of Co3(PO4)2–AlPO4 Catalysts

1998 ◽  
Vol 16 (4) ◽  
pp. 285-293 ◽  
Author(s):  
M.R. Mostafa ◽  
F.Sh. Ahmed
Keyword(s):  
Pore Radius ◽  
Surface Acidity ◽  
Total Pore Volume ◽  
Textural Properties ◽  
Acid Sites ◽  
Adsorption Of Nitrogen ◽  
Amorphous Structures ◽  
Ft Ir ◽  
Catalytic Behaviour ◽  
The Mean

Co3(PO4)2, AlPO4 and the binary system Co3(PO4)2-AlPO4 with different compositions were prepared by the coprecipitation method. The structural properties of these samples were determined using XRD, DTA and FT-IR techniques. The textural properties were determined from the adsorption of nitrogen at 77 K. The surface acidity was measured by a calorimetric titration method. The samples were tested as catalysts in the dehydration of ethanol and isopropanol using a pulse microcatalytic technique. The data obtained from XRD and FT-IR indicate the amorphous structures of the prepared catalysts. An increase in Co3(PO4)2 content led to a decrease in the surface area and in the total pore volume and an increase in the mean pore radius. The surface acidity of the catalyst depends on the chemical composition; the surface acidity increased with an increase in the AlPO4 content. The dehydration temperature and the distribution of acid sites are important parameters in determining the selectivity and activity of the catalyst.

THE DETERMINATION OF PORE SIZE DISTRIBUTION AND SURFACE AREA FROM ADSORPTION ISOTHERMS

1955 ◽  
Vol 33 (2) ◽  
pp. 215-231 ◽  
Author(s):  
E. M. Voigt ◽  
R. H. Tomlinson
Keyword(s):  
Pore Size Distribution ◽  
Pore Size ◽  
Size Distribution ◽  
Surface Area ◽  
Pore Radius ◽  
Weighted Average ◽  
Vycor Glass ◽  
Porous Vycor Glass ◽  
The Mean

Theoretical isotherms have been developed which when compared to experimental isotherms showing hysteresis, allow the calculation of pore size, pore size distribution, and surface area of the sorbent. Interpretation of some experimental isotherms obtained with porous vycor glass shows that this system can best be represented by the "ink bottle" pore model with a Gaussian distribution of pore sizes. The mean pore radius of the porous glass is about two thirds of the Kelvin radius, and the surface area greater than that obtained from the B.E.T. theory. The Kelvin radius is interpreted as a weighted average, but the B.E.T. surface area appears more fundamentally different.

A Novel Method for Analyzing Pore Size Distribution of Complex Geometry Shaped Porous Shale

2020 ◽  
Vol 1003 ◽  
pp. 134-143
Author(s):  
Yang Ming ◽  
Lin Mian
Keyword(s):  
Porous Media ◽  
Pore Size Distribution ◽  
Pore Size ◽  
Size Distribution ◽  
Complex Geometry ◽  
Capillary Condensation ◽  
Relative Pressure ◽  
Differential Function ◽  
Novel Method

This article proposes the differential BJH equation based on the principles of multilayer adsorption and capillary condensation, which was simplified by theoretical investigation and experiments. This work indicates that the differential function of isotherm and the differential function of pore size to relative pressure determine the pore size distribution of porous media. The differential BJH model can be used to explain the source of the false peak in pore size distribution and to calculate the pore size distribution of different shapes of pores in a porous media with a porous structure. It has an excellent application prospect in the characterization of complex pore structure represented by shale.

Possibilities of determining the polymodal pore-size distribution from physical adsorption of nitrogen

1987 ◽  
Vol 52 (5) ◽  
pp. 1160-1166
Author(s):  
Dagmar Tomanová ◽  
Petr Schneider
Keyword(s):  
Pore Size ◽  
Size Distribution ◽  
Physical Adsorption ◽  
Relative Pressure ◽  
Size Distributions ◽  
Porous Sample ◽  
Fine Grained ◽  
Mesopore Size Distribution ◽  
Pore Size Distributions ◽  
Adsorption Of Nitrogen

It is shown, on the basis of experimentally determined adsorption isotherms of physical adsorption of nitrogen on two- and three-component mixtures of fine grained porous glasses with narrow pore-size distributions, that the polymodal mesopore-size distribution curves can be evaluated in case that the porous sample contains groups of mesopores differing rather significantly in size. The differentiation of groups of pores gets worse with wider pores where the demands on the accuracy of the relative pressure measurement grow stronger.

UPAYA MENINGKATKAN HASIL BELAJAR IPA MELALUI PENGGUNAAN VIDEO PEMBELAJARAN BAGI SISWA KELAS IV DI SDN 187/IV KOTA JAMBI

2015 ◽  
Vol 8 (2) ◽  
pp. 93
Author(s):  
Juniar Siregar
Keyword(s):  
Action Research ◽  
Research Method ◽  
Research Report ◽  
The Third ◽  
The Media ◽  
The Subject ◽  
The Mean ◽  
Classroom Action Research

This study presents a research report on improving students’ Learning results on IPA through Video. The objective was to find out whether students’ learning result improved when they are taught by using Video. It was conducted using classroom action research method. The subject of the study was the Grade IV students of SDN 187/IV Kota Jambi which is located on Jln. Adi Sucipto RT 05 Kecamatan Jambi Selatan, and the number of the students were 21 persons. The instruments used were test. In analyzing the data, the mean of the students’ score for the on fisrt sycle was 65,4 (42,85%) and the mean on cycle two was 68,5 (37,15%) and the mean of the third cycle was 81,4 (100%). Then it can be concluded that the use of video on learning IPA can improve the students’ learning result. It is suggested that teachers should use video as one of the media to improve students’ learning result on IPA.Keywords : IPA, students’ learning result, video

IMPROVING STUDENTS’ ACHIEVEMENT IN WRITING RECOUNT TEXT THROUGH THINK PAIR SHARE

2013 ◽  
Vol 2 (1) ◽  
Author(s):  
Hotria Manik ◽  
Elia Masa Ginting
Keyword(s):  
Action Research ◽  
Quantitative Data ◽  
Qualitative Data ◽  
Writing Achievement ◽  
The Third ◽  
Post Test ◽  
Class Viii ◽  
The Subject ◽  
The Mean ◽  
Writing Tests

This study attempts to improve students’ writing achievement in recount text through Think-Pair-Share Strategy. This study was conducted by using classroom action research. The subject of the research was class VIII-1 SMPN 1 Pematangsiantar. The number of the students was 32 students, consisted of 5 males and twenty seven females. The research was conducted in two cycles and consisted of six meetings. The instruments for collecting data were writing tests as the quantitative data and diary notes, observation sheet, interview sheet and questionnaire sheet as qualitative data. Based on the writing score, students’ scores kept improving in every test. In analyzing the data, the mean of the students’ score for the first test as a pre-test was 57.84, for the second test as a post test I was 73.56, for the third test as a post test II was 77.56. Based on diary notes, observation sheet and questionnaire sheet, it was found that students were actively involved in writing process. The result of the research showed that Think-Pair-Share Strategy can improve students’ achievement in writing recount text.   Keywords: Think Pair Share, Writing, Recount text, Action research

IMPROVING STUDENTS’ WRITING ACHIEVEMENT IN THE REPORT TEXT THROUGH FILM

2013 ◽  
Vol 2 (4) ◽  
Author(s):  
Esra N.F. Hutahaean And Tjut Ernidawati
Keyword(s):  
Action Research ◽  
Research Method ◽  
Writing Achievement ◽  
The Third ◽  
Total Percentage ◽  
The Subject ◽  
The Mean ◽  
Report Text

This research concerns on improving students’ writing achievement in the report text through film.  The objective was to find out the improvement of students’ writing achievement in writing the report text through film. This research was conducted by using action research method. The subject of the research was XI IPA grade students of SMA SWASWTA JOSUA Medan. The numbers of students were thirty one students. They were taught writing the report text through film. The instruments used were writing report text test, diary notes, interview sheets, questionnaire sheets and observation sheets. In analyzing data, the mean of students’ score for the first competency test was 43.1, for the second competency test was 64.8 and for the third competency test was 76.3 and the total percentage of improvement from the first competency test to the third competency test was 84.1%. The conclusion is that through watching film can improve the students’ writing achievement in the report text. It is suggested that teachers should apply watching film as one of media to improve students’ writing achievement in the report text.

Correlations Between the Values of Maternal Glycemia from the Last Trimester of Pregnancy and Fetal Birth Weight

2013 ◽  
Vol 20 (3) ◽  
pp. 259-265
Author(s):  
Monica Vereş ◽  
Aurel Babeş ◽  
Szidonia Lacziko
Keyword(s):  
First Trimester ◽  
Mean Value ◽  
Fetal Macrosomia ◽  
Entire Group ◽  
Third Trimester ◽  
The Third ◽  
Group I ◽  
Fetal Birth Weight ◽  
First Trimester Of Pregnancy ◽  
The Mean

Abstract Background and aims: Gestational diabetes represents a form of diabetes diagnosed during pregnancy that is not clearly overt diabetes. In the last trimester of gestation the growth of fetoplacental unit takes place, thus maternal hyperglycemia will determine an increased transplacental passage, hyperinsulinemia and fetal macrosomia. The aim of our study was that o analyzing the effect of maternal glycemia from the last trimester of pregnancy over fetal weight. Material and method: We run an observational study on a group of 46 pregnant women taken into evidence from the first trimester of pregnancy, separated in two groups according to blood glucose determined in the third trimester (before birth): group I normoglycemic and group II with hyperglycemia (>92mg/dl). Results: The mean value of third trimester glycemia for the entire group was of 87.13±22.03. The mean value of the glycemia determined in the third trimester of pregnancy was higher in the second group (109.17 mg/dl) in comparison to the first group (74.,21 mg/dl). The ROC curve for third trimester glycemia as fetal macrosomia appreciation test has an AUC of 0.517. Conclusions: Glycemia determined in the last trimester of pregnancy cannot be used alone as the predictive factor for fetal macrosomia.

scholarly journals Publication activity of chief and consultant general/visceral surgeons in German university hospitals—a ten-year analysis

2021 ◽  
Author(s):  
Eva C. Böckmann ◽  
E. S. Debus ◽  
R. T. Grundmann
Keyword(s):  
Impact Factor ◽  
Publication Activity ◽  
University Hospitals ◽  
Cumulative Impact ◽  
University Departments ◽  
The Third ◽  
Publication Number ◽  
Significant Difference ◽  
The Mean ◽  
Number Of Publications

Abstract Purpose The publication activity of 38 German general/visceral surgery university departments, documented by first or last authorship from staff surgeons (chief and consultants), was evaluated. Methods The observation period extended from 2007 to 2017 and all PubMed-listed publications were considered. Impact factor (IF) was evaluated through the publishing journal’s 5-year IF in 2016, as was the IF for each individual publication. Ranking was expressed in quartiles. Results The staff surgeons of the 38 departments comprised 442 surgeons, of which only 351 (79.4%) were active as first or last authors. Four thousand six hundred and ninety-nine publications published in 702 journals were recorded. The four leading departments in publication number published as much as the last 20 departments (1330 vs. 1336 publications, respectively). The mean of the first (most active) department quartile was 19.6 publications, the second 15.4, the third 11.0, and the last quartile 7.6 per publishing surgeon. The total cumulative impact factor was 14,130. When examining the mean number of publications per publishing surgeons per the 10 year period, the mean of the first quartile was 57.9 cumulative IF, the second 45.0, the third 29.5, and the fourth quartile 17.1. With 352 (7.5%) publications, the most frequently used journal was Chirurg, followed by Langenbeck’s Archives of Surgery with 274 (5.8%) publications. Pancreas-related topics led in terms of publication number and IF generated per individual publication. Conclusion A significant difference in publication performance of individual departments was apparent that cannot be explained by staff number. This indicates that there are as yet unknown factors responsible for minor publication activity in many university departments.

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