181,353 research outputs found
A study of the acid lability and acute toxicity of dimethoxymethane in rats
No full textThe pH stability and acute oral toxicity of dimethoxymethane (DMM) in rats were studied, In in vitro studies, DMM was found to be stable in artificial gastric juice at pH 2.5 and above but readily hydrolyzed at pH2 and below, with 1 mole of DMM producing approximately 1 mole of formaldehyde and 2 moles of methanol. DMM incubated in sealed, excised stomachs appeared to equilibrate with the external incubation fluid over a 24-hour period without significant hydrolysis, In the toxicity study, three groups of female rats (n = 5) were administered, by gavage, phosphate-buffered saline (control), DMM (31 mmoles/kg body weight [bw]/day), or methanol (MeOH) (30 mmoles/kg bw/day), respectively, for 3 consecutive days and then sacrificed on day 5, Transient ataxia lasting about 30 minutes was observed in animals following DMM administration, increased urine volume was observed in the DMM group at the end of days 4 and 5, Markedly elevated level of formic acid was present in the urine of the MeOH group at days 1, 2, and 3, but not in the DMM group, Urinary ascorbic acid levels were increased In the DMM group on days 1, 2 and 3, and returned to baseline level at days 4 and 5, Microscopic examination detected no abnormal histological changes in the liver and kidneys of MeOH- or DMM-treated animals, No treatment effects were observed on the following endpoints: organ weights (liver, heart, thymus, kidneys), serum corticosterone, serum chemistry profile, hematology, hepatic phase 1 and phase 2 mixed-function oxidase activities, hepatic and serum thiobarbituric acid, hepatic glutathione, urinary protein, and urinary N-acetylglucosaminidase activity, These observations suggested that hydrolysis of DMM in the stomach required a gastric acidity below pH 2,5, At higher DW, intact DMM readily penetrated the stomach and therefore likely reached the circulation and other body tissues. There was no significant hydrolysis of orally administered DMM, and the acute effects were limited to transient ataxia and biochemical responses in the liver.PT: J; CR: *ACGIH, THRESH VAL TLVS CHEM *CCAC, 1993, GUID CAR US EXP AN *HSDB, 1998, HSDB *IARC, 1995, IARC MON EV CARC RIS, V62, P217 *US EPA, 1998, CHEM HAZ DAT AV STUD *USP, 1995, US PHARM, V23 BENINI L, 1995, GUT, V36, P825 BURCHELL B, 1981, METHOD ENZYMOL, V77, P169 BURKE MD, 1985, BIOCHEM PHARMACOL, V34, P3337 CHIVERTON SG, 1989, ALIMENT PHARM THERAP, V3, P403 CHU I, 1992, ORGANOHALOGEN COMPOU, V10, P17 DODGE L, 1994, NTIDDE94006949 GARGAS ML, 1989, TOXICOL APPL PHARM, V98, P87 GRADY S, 1986, J ANAL TOXICOL, V10, P1 HABIG WH, 1974, J BIOL CHEM, V249, P7130 JONES AW, 1993, CLIN CHEM, V39, P1837 KAO CH, 1998, J NUCL MED, V39, P1798 KONTUREK JW, 1993, SCAND J GASTROENTERO, V28, P401 LUBET RA, 1985, MUTAT RES, V142, P127 MAHE S, 1995, GASTROEN CLIN BIOL, V19, P20 MARICQ MM, 1998, 216 AM CHEM SOC NAT, V43, P578 MCLAUCHLAN G, 1989, GUT, V30, P573 MCMARTIN KE, 1980, AM J MED, V68, P414 POON R, 1992, P 4 ANN M INT SOC ST, P146 POON R, 1994, J BIOCHEM TOXICOL, V9, P297 POON R, 1995, INHAL TOXICOL, V7, P1195 ROGERS JM, 1993, TERATOLOGY, V47, P175 SAKANASHI TM, 1996, TERATOLOGY, V54, P198 SCHENKMAN JB, 1967, MOL PHARMACOL, V3, P113 TOMILINA LA, 1984, GIG TR PROF ZABOL, V6, P27 VANHERCK H, 1991, LAB ANIM, V25, P325 VINET B, 1987, CLIN CHEM, V33, P2204 YAGI K, 1982, LIPID PEROXIDE BIOL, P232; NR: 33; TC: 4; J9: INT J TOXICOL; PG: 7; GA: 331DTSource type: Electronic(1
Ekstraksi Model Gummel Poon dengan Metode Pencocokan Kurva
No full textSimulator rangkaian elektronika berbasis SPICE menerapkan model Gummel Poon banyak digunakan pelajar. Perancang harus memiliki parameter model dari devais elektronika sebelum melakukan analisis dengan bantuan komputer. Jika komponen yang digunakan diperoleh dari pasar, ada kemungkinan karakteristiknya tidak sesuai dengan lembar data dan / atau model dalam pustaka SPICE. Oleh karena itu perlu dikembangkan metode ekstrasi parameter model. Metode ekstaksi model Gummel Poon menerapkan analisis regresi telah diuji dan disimulasi. Hasilnya menunjukkan bahwa faktor kualitas kurva yang dicocokkan, R2, sangat dekat dengan 1. Hasil ini cukup memuaskan dalam simulasi.
Kata Kunci— Ekstraksi, Gummel Poon, karakteristik statik, kuadrat terkecil, pencocokan kurva
Ekstraksi Model Gummel Poon Dengan Metode Pencocokan Kurva
No full textSimulator rangkaian elektronika berbasis SPICE menerapkan model Gummel Poon banyak digunakan pelajar. Perancang harus memiliki parameter model dari devais elektronika sebelum melakukan analisis dengan bantuan komputer. Jika komponen yang digunakan diperoleh dari pasar, ada kemungkinan karakteristiknya tidak sesuai dengan lembar data dan / atau model dalam pustaka SPICE. Oleh karena itu perlu dikembangkan metode ekstrasi parameter model. Metode ekstaksi model Gummel Poon menerapkan analisis regresi telah diuji dan disimulasi. Hasilnya menunjukkan bahwa faktor kualitas kurva yang dicocokkan, R2, sangat dekat dengan 1. Hasil ini cukup memuaskan dalam simulasi.Kata Kunci— Ekstraksi, Gummel Poon, karakteristik statik, kuadrat terkecil, pencocokan kurva
Estimation of on-road PM₂.₅ distributions by combining satellite top-of-atmosphere with microscale geographic predictors for healthy route planning
No full text202505 bcchVersion of RecordOthersNational Key R&D Program of China (2019YFB2103102); Otto Poon Charitable Foundation Smart Cities Research Institute; The Hong Kong Polytechnic University (Work Program: CD03)PublishedC
Ekstraksi Parameter Model Gummel-Poon dengan Metode Pencocokan Kurva
No full textModel Gummel-Poon adalah rangkaian listrik ekivalen yang meniru perilaku elektrik transistor persambungan bipolar. Simulator rangkaian elektronika berbasis SPICE menerapkan model Gummel Poon banyak digunakan pelajar. Perancang harus memiliki parameter model dari devais elektronika sebelum melakukan analisis dengan bantuan komputer. Jika komponen yang digunakan diperoleh dari pasar, ada kemungkinan karakteristiknya tidak sesuai dengan lembar data dan / atau model dalam pustaka SPICE. Oleh karena itu perlu dikembangkan metode ekstrasi parameter model. Tujuan penelitian ini adalah untuk mendapatkan metode ekstraksi parameter BF , IS , ISE , NE , NF , IKF , RE , VAF , dan VAR dari model Gummel-Poon. Pengembangan metode ekstraksi dilakukan dengan melakukan penyederhanaan persamaan model. Penyederhanaan pertama adalah dengan memperhatikan modus kerja transistor dan kedua adalah dengan memilih kisaran tegangan basis-emiter. Bentuk eksponensial dari persamaan ditransformasi menjadi fungsi linier dengan operasi logaritma sehingga pencocokan kurva linier dapat diterapkan. Metode kuadrat terkecil digunakan untuk ekstraksi parameter model yang ada di dalam persaman yang tidak dapat diubah menjadi fungsi linier.
Metode ekstraksi diuji dengan memberi data arus-tegangan yang diambil dari simulator berbasis SPICE. Parameter hasil ekstraksi dimasukkan ke dalam persamaan model Gummel-Poon dan digunakan untuk membuat kurva Beta(V BE ). Kurva perhitungan dan hasil simulasi dibandingkan dengan metode kuadrat terkecil. Rendahnya nilai E tot dan faktor kualitas, R 2 , yang dekat dengan satu menjadi indikator keberhasilan ekstraksi.
Hasil pengujian menunjukkan bahwa kurva perhitungan dan hasil simulasi sangat berimpit. Harga E tot cukup rendah, kurang dari 0,002, dan R 2 dekat dengan satu, 1,011. Perbandingan parameter model hasil ekstrasi dan parameter simulasi memiliki selisih maksimum 1,1% yaitu pada parameter IKF
Appropriate Similarity Measures for Author Cocitation Analysis
No full textWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
"Closing the R&D Gap, Evaluating the Sources of R&D Spending"
No full textBoth spending and tax policies have been implemented in the United States with the goal of stimulating private sector research and development (R&D). Karier questions whether current R&D policy, especially the research and experimentation tax credit, can contribute to closing the gap between nondefense expenditures on R&D in the United States and such expenditures in other countries, such as Japan and Germany. He also explores possible changes to our current R&D policy to make it more effective.
Online public opinion during the first epidemic wave of COVID-19 in China based on Weibo data
No full text202212 bcchVersion of RecordOthersthe National Key R&D Program of China (2019YFB2103102)Research Grant Council, HKSAR Government (C5079-21G)Otto Poon Charitable Foundation Smart Cities Research Institute, The Hong Kong Polytechnic University (Work Program: CD03)Innovation and Technology Fund, HKSAR Government (ITP/041/21LP)PublishedC
Going Beyond Counting First Authors in Author Co-citation Analysis
No full textThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
A Modular Approach to Educational Technology Professional Development Among Post-Secondary Educators in Alberta, Canada
No full textPCF1 // Working paper presented by Michael Szabo, Mohamed Ally, William Fricker, Richard Poon, and Clayton R Wright, at the First Pan-Commonwealth Forum on Open Learning (PCF1) in Bandar Seri Begawan, Brunei Darussalam. /
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