Sabtu, 03 Juli 2010

Abu Musa Jabir bin Hayyan

sumber : http://tonyoke.wordpress.com/2009/06/22/abu-musa-jabir-ibn-hayyan-the-father-of-chemistery/#more-589
http://id.wikipedia.org/wiki/Abu_Musa_Jabir_bin_Hayyan

Abu Musa Jabir bin Hayyan, atau dikenal dengan nama Geber di dunia Barat, diperkirakan lahir di Kuffah, Irak pada tahun 750 dan wafat pada tahun 803. Kontribusi terbesar Jabir adalah dalam bidang kimia. Keahliannya ini didapatnya dengan ia berguru pada Barmaki Vizier, di masa pemerintahan Harun Ar-Rasyid di Baghdad. Ia mengembangkan teknik eksperimentasi sistematis di dalam penelitian kimia, sehingga setiap eksperimen dapat direproduksi kembali. Jabir menekankan bahwa kuantitas zat berhubungan dengan reaksi kimia yang terjadi, sehingga dapat dianggap Jabir telah merintis ditemukannya hukum perbandingan tetap.

Kontribusi lainnya antara lain dalam penyempurnaan proses kristalisasi, distilasi, kalsinasi, sublimasi dan penguapan serta pengembangan instrumen untuk melakukan proses-proses tersebut.
[sunting] Buku

Karya Jabir antara lain:

* Kitab Al-Kimya (diterjemahkan ke Inggris menjadi The Book of the Composition of Alchemy)
* Kitab Al-Sab'een
* Kitab Al Rahmah
* Al Tajmi
* Al Zilaq al Sharqi
* Book of The Kingdom
* Book of Eastern Mercury
* Book of Balance.


Abu Musa Jabir Ibn Hayyan “The Father of Chemistery”
Posted by tonyoke under Abu Musa Jabir Ibn Hayyan “The Father of Chemistery”
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Ilmu kimia merupakan sumbangan penting yang telah diwariskan para kimiawan Muslim di abad keemasan bagi peradaban modern. Para ilmuwan dan sejarah Barat pun mengakui bahwa dasar-dasar ilmu kimia modern diletakkan para kimiawan Muslim. Tak heran, bila dunia menabalkan kimiawan Muslim bernama Jabir Ibnu Hayyan sebagai ‘Bapak Kimia Modern’.”Para kimiawan Muslim adalah pendiri ilmu kimia,” cetus Ilmuwan berkebangsaan Jerman di abad ke-18 M. Tanpa tedeng aling-aling, Will Durant dalam The Story of Civilization IV: The Age of Faith, juga mengakui bahwa para kimiawan Muslim di zaman kekhalifahanlah yang meletakkan fondasi ilmu kimia modern.

Menurut Durant, kimia merupakan ilmu yang hampir seluruhnya diciptakan oleh peradaban Islam. “Dalam bidang ini (kimia), peradaban Yunani (seperti kita ketahui) hanya sebatas melahirkan hipotesis yang samar-samar,” ungkapnya.

Sedangkan, peradaban Islam, papar dia, telah memperkenalkan observasi yang tepat, eksperimen yang terkontrol, serta catatan atau dokumen yang begitu teliti.Tak hanya itu, sejarah mencatat bahwa peradaban Islam di era kejayaan telah melakukan revolusi dalam bidang kimia.

Kimiawan Muslim telah mengubah teori-teori ilmu kimia menjadi sebuah industri yang penting bagi peradaban dunia. Dengan memanfaatkan ilmu kimia, Ilmuwan Islam di zaman kegemilangan telah berhasil menghasilkan sederet produk dan penemuan yang sangat dirasakan manfaatnya hingga kini.

Berkat revolusi sains yang digelorakan para kimiawan Muslim-lah, dunia mengenal berbagai industri serta zat dan senyawa kimia penting. Adalah fakta tak terbantahkan bahwa alkohol, nitrat, asam sulfur, nitrat silver, dan potasium–senyawa penting dalam kehidupan manusia modern–merupakan penemuan para kimiawan Muslim. Revolusi ilmu kimia yang dilakukan para kimiawan Muslim di abad kejayaan juga telah melahirkan teknik-teknik sublimasi, kristalisasi, dan distilasi. Dengan menguasai teknik-teknik itulah, peradaban Islam akhirnya mampu membidani kelahiran sederet industri penting bagi umat manusia, seperti industri farmasi, tekstil, perminyakan, kesehatan, makanan dan minuman, perhiasan, hingga militer.

Pencapaian yang sangat fenomenal itu merupakan buah karya dan dedikasi para ilmuwan seperti Jabir Ibnu Hayyan, Al-Razi, Al-Majriti, Al-Biruni, Ibnu Sina, dan masih banyak yang lainnya. Setiap kimiawan Muslim itu telah memberi sumbangan yang berbeda-beda bagi pengembangan ilmu kimia. Jabir (721 M-815 M), misalnya, telah memperkenalkan eksperimen atau percobaan kimia. Ia bekerja keras mengelaborasi kimia di sebuah laboratorium dengan serangkaian eksperimen. Salah satu ciri khas eksperimen yang dilakukannya bersifat kuantitatif. Ilmuwan Muslim berjuluk ‘Bapak Kimia Modern’ itu juga tercatat sebagai penemu sederet proses kimia, seperti penyulingan/distilasi, kristalisasi, kalnasi, dan sublimasi.

Sang ilmuwan yang dikenal di Barat dengan sebutan ‘Geber’ itu pun tercatat berhasil menciptakan instrumen pemotong, pelebur, dan pengkristal. Selain itu, dia pun mampu menyempurnakan proses dasar sublimasi, penguapan, pencairan, kristalisasi, pembuatan kapur, penyulingan, pencelupan, dan pemurnian.Berkat jasanya pula, teori oksidasi-reduksi yang begitu terkenal dalam ilmu kimia terungkap. Senyawa atau zat penting seperti asam klorida, asam nitrat, asam sitrat, dan asam asetat lahir dari hasil penelitian dan pemikiran Jabir. Ia pun sukses melakukan distilasi alkohol. Salah satu pencapaian penting lainnya dalam merevolusi kimia adalah mendirikan industri parfum.
untitledIlmuwan Muslim lainnya yang berjasa melakukan revolusi dalam ilmu kimia adalah Al-Razi (lahir 866 M). Dalam karyanya berjudul, Secret of Secret, Al-Razi mampu membuat klasifikasi zat alam yang sangat bermanfaat. Ia membagi zat yang ada di alam menjadi tiga, yakni zat keduniawian, tumbuhan, dan zat binatang. Soda serta oksida timah merupakan hasil kreasinya.Al-Razi pun tercatat mampu membangun dan mengembangkan laboratorium kimia bernuansa modern. Ia menggunakan lebih dari 20 peralatan laboratorium pada saat itu. Dia juga menjelaskan eksperimen-eksperimen yang dilakukannya. “Al-Razi merupakan ilmuwan pelopor yang menciptakan laboratorium modern,” ungkap Anawati dan Hill.

Bahkan, peralatan laboratorium yang digunakannya pada zaman itu masih tetap dipakai hingga sekarang. “Kontribusi yang diberikan Al-Razi dalam ilmu kimia sungguh luar biasa penting,” cetus Erick John Holmyard (1990) dalam bukunya, Alchemy. Berkat Al-Razi pula industri farmakologi muncul di dunia.

Sosok kimiawan Muslim lainnya yang tak kalah populer adalah Al-Majriti (950 M-1007 M). Ilmuwan Muslim asal Madrid, Spanyol, ini berhasil menulis buku kimia bertajuk, Rutbat Al-Hakim. Dalam kitab itu, dia memaparkan rumus dan tata cara pemurnian logam mulia. Dia juga tercatat sebagai ilmuwan pertama yang membuktikan prinsip-prinsip kekekalan masa –yang delapan abad berikutnya dikembangkan kimiawan Barat bernama Lavoisier.

Sejarah peradaban Islam pun merekam kontribusi Al-Biruni (wafat 1051 M) dalam bidang kimia dan farmakologi. Dalam Kitab Al-Saydalah (Kitab Obat-obatan), dia menjelaskan secara detail pengetahuan tentang obat-obatan. Selain itu, ia juga menegaskan pentingnya peran farmasi dan fungsinya. Begitulah, para kimiawan Muslim di era kekhalifahan berperan melakukan revolusi dalam ilmu kimia. heri ruslan/RioL

Baca :
1) http://en.wikipedia.org/wiki/Alchemy_and_chemistry_in_Islam

2) http://en.wikipedia.org/wiki/Jabir_ibn_Hayyan

3) http://en.wikipedia.org/wiki/Al-Razi

4) http://labitacoradealchemy.blogspot.com

Flame Test 07. warna api

The element song

C-reactive protein concentration and risk of coronary heart disease, stroke, and mortality: an individual participant meta-analysis

sumber : http://www.sciencedirect.com/science?_ob=ArticleURL&_udi=B6T1B-4Y0CXR9-1&_user=10&_coverDate=01%2F15%2F2010&_rdoc=1&_fmt=high&_orig=search&_sort=d&_docanchor=&view=c&_acct=C000050221&_version=1&_urlVersion=0&_userid=10&md5=3915578ad09a876b45dbbf032a06eb88

The Emerging Risk Factors Collaboration‡

Available online 22 December 2009.


Refers to: C-reactive protein and cardiovascular risk: more fuel to the fire
The Lancet, Volume 375, Issue 9709, 9 January 2010-15 January 2010, Pages 95-96,
S Matthijs Boekholdt, John JP Kastelein
PDF (217 K)
Referred to by: C-reactive protein and cardiovascular risk: more fuel to the fire
The Lancet, Volume 375, Issue 9709, 9 January 2010-15 January 2010, Pages 95-96,
S Matthijs Boekholdt, John JP Kastelein
PDF (217 K)
Summary
Background

Associations of C-reactive protein (CRP) concentration with risk of major diseases can best be assessed by long-term prospective follow-up of large numbers of people. We assessed the associations of CRP concentration with risk of vascular and non-vascular outcomes under different circumstances.
Methods

We meta-analysed individual records of 160 309 people without a history of vascular disease (ie, 1·31 million person-years at risk, 27 769 fatal or non-fatal disease outcomes) from 54 long-term prospective studies. Within-study regression analyses were adjusted for within-person variation in risk factor levels.
Results

Loge CRP concentration was linearly associated with several conventional risk factors and inflammatory markers, and nearly log-linearly with the risk of ischaemic vascular disease and non-vascular mortality. Risk ratios (RRs) for coronary heart disease per 1-SD higher loge CRP concentration (three-fold higher) were 1·63 (95% CI 1·51–1·76) when initially adjusted for age and sex only, and 1·37 (1·27–1·48) when adjusted further for conventional risk factors; 1·44 (1·32–1·57) and 1·27 (1·15–1·40) for ischaemic stroke; 1·71 (1·53–1·91) and 1·55 (1·37–1·76) for vascular mortality; and 1·55 (1·41–1·69) and 1·54 (1·40–1·68) for non-vascular mortality. RRs were largely unchanged after exclusion of smokers or initial follow-up. After further adjustment for fibrinogen, the corresponding RRs were 1·23 (1·07–1·42) for coronary heart disease; 1·32 (1·18–1·49) for ischaemic stroke; 1·34 (1·18–1·52) for vascular mortality; and 1·34 (1·20–1·50) for non-vascular mortality.
Interpretation

CRP concentration has continuous associations with the risk of coronary heart disease, ischaemic stroke, vascular mortality, and death from several cancers and lung disease that are each of broadly similar size. The relevance of CRP to such a range of disorders is unclear. Associations with ischaemic vascular disease depend considerably on conventional risk factors and other markers of inflammation.
Funding

British Heart Foundation, UK Medical Research Council, BUPA Foundation, and GlaxoSmithKline.

Carbon nanotube–polymer composites: Chemistry, processing, mechanical and electrical properties

sumber : http://www.sciencedirect.com

Zdenko Spitalskya, 1, Dimitrios Tasisb, Corresponding Author Contact Information, E-mail The Corresponding Author, Konstantinos Papagelisb and Costas Galiotisa, b

a FORTH/ICE-HT, Stadiou Str., 265 04 Rion Patras, Greece

b Department of Materials Science, University of Patras, 265 04 Rio Patras, Greece
Received 8 January 2009;
revised 9 September 2009;
accepted 15 September 2009.
Available online 25 September 2009.

Abstract

Carbon nanotubes have long been recognized as the stiffest and strongest man-made material known to date. In addition, their high electrical conductivity has roused interest in the area of electrical appliances and communication related applications. However, due to their miniscule size, the excellent properties of these nanostructures can only be exploited if they are homogeneously embedded into light-weight matrices as those offered by a whole series of engineering polymers. We review the present state of polymer nanocomposites research in which the fillers are carbon nanotubes. In order to enhance their chemical affinity to engineering polymer matrices, chemical modification of the graphitic sidewalls and tips is necessary. In this review, an extended account of the various chemical strategies for grafting polymers onto carbon nanotubes and the manufacturing of carbon nanotube/polymer nanocomposites is given. The mechanical and electrical properties to date of a whole range of nanocomposites of various carbon nanotube contents are also reviewed in an attempt to facilitate progress in this emerging area.

Keywords: Carbon nanotubes; Polymers; Composites; Processing; Mechanical properties; Electrical properties

Abbreviations: ABS, acrylonitrile–butadiene–styrene copolymer; ACMA, acrylonitrile–methyl acrylate copolymer; AIBN, 2,2′-azobisisobutyronitrile; ATRP, atom transfer radical polymerization; CNT, carbon nanotube; CPP, chlorinated polypropylene; DWCNT, double-walled carbon nanotube; EDS, energy-dispersive X-ray spectroscopy; EMMA, ethyl–methyl methacrylate copolymer; EPDM, ethylene–propylene–diene rubber; EVA, ethylene–vinyl acetate copolymer; EVOH, ethylene–vinyl alcohol copolymer; HDPE, high-density polyethylene; HMW, high molecular weight; LDPE, low density polyethylene; LMW, low molecular weight; MA, maleic anhydride; MBMA, methyl–butyl methacrylate copolymer; MDPE, medium density polyethylene; MEMA, methyl–ethyl methacrylate copolymer; MPTS, methacryloxypropyltrimethoxysilane; MWCNT, multi-walled carbon nanotube; NMP, nitroxide-mediated polymerization; NMR, nuclear magnetic resonance; P3HT, poly(3-hexylthiophene); P3OT, poly(3-octylthiophene); PA, poly-acetylene; PAA, poly(acrylic acid); PABS, poly(m-aminobenzene sulfonic acid); PAM, polyacrylamide; PAMAM, poly(amidoamine); PAN, polyacrylonitrile; PANI, polyaniline; Parmax, poly(benzoyl-1,4-phenylene)-co-(1,3-phenylene); PBA, polybutyl acrylate; PtBA, poly(tert-butyl acrylate); PBMA, poly(butyl methacrylate); PBO, poly(phenylenebenzobisoxazole); PBT, poly(butyl terephthalate); PC, polycarbonate; PCL, polycaprolactone; PDEAEMA, poly[2-(diethylamino)ethyl methacrylate]; PDI, polydispersity index; PDMEMA, poly[2-(dimethylamino)ethyl methacrylate]; PDMS, polydimethylsiloxane; PDPA, polydiphenylamime; PE, polyethylene; PEG, polyethyleneglycol; PEI, polyethyleneimine; PEMA, poly(ethyl methacrylate); PEO, polyethyleneoxide; PET, poly(ethyl terephthalate); PETI, phenylethynyl-terminated imide; PGMA, poly(glycerol monomethacrylate); PHEMA, poly(2-hydroxyethyl methacrylate); PHET, poly[3-(2-hydroxyethyl)-2,5-thienylene]; PHPMA, poly[N-(2-hydroxypropyl)methacrylamide]; PI, polyimide; PIMA, poly(imidazolium methacrylate); PLLA, poly(l-lactic acid); PLLA-g-AA, poly(l-lactic acid) grafted with poly(acrylic acid) chains; PMDMAS, poly[3-(N-(3-methacrylamidopropyl)-N,N-dimethyl)ammoniopropanatesulfonate]; PMMA, poly(methyl methacrylate); PMMAHEMA, poly[(methyl methacrylate)-co-(2-hydroxyethyl methacrylate)]; PmPV, poly(m-phenylenevinylene-co-2,5-dioctoxy-p-phenylenevinylene); PNIPAAm, poly(N-isopropylacrylamide); PP, polypropylene; PPE, poly(p-phenylene ethynylene); PPEI-EI, poly(propionylethylenimine-co-ethylimine); PPS, poly(phenylene sulfide); PPY, polypyrrole; PS, polystyrene; PSS, poly(sodium 4-styrenesulfonate); PSV, poly(styrene-co-p-(4-(4′-vinylphenyl)-3-oxobutanol)); PTH, polythiophene; PU, polyurethane; PVA, poly(vinyl alcohol); PVAc, poly(vinyl acetate); PVAc-VA, poly(vinyl acetate-co-vinyl alcohol); PVC, poly(vinyl chloride); PVDF, poly(vinylidene fluoride); PVK, poly(N-vinyl carbazole); PVKV, poly(N-vinyl carbazole-co-p-(4-(4′-vinylphenyl)-3-oxobutanol)); PVP, polyvinylpyrrolidone; P2VP, poly(2-vinylpyridine); P4VP, poly(4-vinylpyridine); RAFT, reversible addition-fragmentation chain transfer polymerization; ROP, ring opening polymerization; SAN, styrene–acrylonitrile copolymer; SBA, styrene–butyl acrylate copolymer; SBBS, styrene–butadiene–butylene–styrene copolymer; SBR, styrene–butadiene rubber; SCMS, styrene-p-chloromethylstyrene copolymer; SE, silicone elastomer; SEC, size exclusion chromatography; SIBS, poly(styrene-b-isobutylene-b-styrene); SMA, styrene maleic anhydride copolymer; STM, scanning tunneling microscopy; SWCNT, single-walled carbon nanotube; TDI, toluene diisocyanate; TEMPO, 2,2,6,6-tetramethylpiperidinyl-1-oxy; TGA, thermogravimetric analysis; THF, tetrahydrofuran; UHMWPE, ultra high molecular weight polyethylene; WBPU, waterborne polyurethane
Article Outline

1. Introduction
2. Modification of carbon nanotubes with polymers

2.1. Method “grafting to”

2.1.1. Ester linkage between oxidized CNTs and polymers
2.1.2. Amide linkage between oxidized CNTs and polymers
2.1.3. Grafting by a radical mechanism
2.1.4. Nucleophilic addition/coupling reactions
2.1.5. Cycloaddition
2.1.6. Condensation
2.1.7. Sonochemical reaction

2.2. Method “grafting from”

2.2.1. Atom transfer radical polymerization (ATRP)
2.2.2. Reversible addition-fragmentation chain transfer (RAFT)
2.2.3. Ring opening polymerization (ROP)
2.2.4. Free radical polymerization
2.2.5. Cationic/anionic polymerization
2.2.6. Condensation polymerization
2.2.7. Reduction/oxidation polymerization
2.2.8. Metallocene catalysis polymerization
2.2.9. Electrochemical grafting
2.2.10. Nitroxide-mediated radical polymerization

2.3. Mixed mechanism
2.4. Endohedral filling

3. Composite processing

3.1. Solution processing of CNTs and polymer
3.2. Bulk mixing
3.3. Melt mixing
3.4. In situ polymerization
3.5. CNT-based fibers and films

3.5.1. Composite fibers
3.5.2. Composite films

4. Mechanical properties of carbon nanotube/polymer composites

4.1. Literature data
4.2. General conclusions-remarks

5. Electrical properties of carbon nanotube/polymer composites

5.1. Literature data
5.2. General conclusions-remarks

Acknowledgements
References

Iceland volcano: Why a cloud of ash has grounded flights

sumber : http://news.bbc.co.uk/2/hi/science/nature/8621992.stm

ANALYSIS
By Victoria Gill
Science reporter, BBC News

The volcanic ash cloud
The volcanic ash cloud reached about 55,000ft, Eurocontrol says

More than 1,000km from the event itself, Iceland's second volcanic eruption in the space of a month has caused flights in the UK to be grounded.

Scientists and aviation authorities are continuing to monitor a plume of volcanic ash that is moving southwards over the UK.

The entirety of UK airspace closed from noon on Thursday.

National Air Traffic Services said: "The current restrictions across UK controlled airspace due to the volcanic ash cloud will remain in place until at least 0100 BST on Tuesday 20 April."

The eruption ejected the plume, which is made up of fine rock particles, up to 11km into the atmosphere.

"This ash cloud is now drifting with the high altitude winds," said Dr David Rothery, a volcano researcher from the UK's Open University.

"The main mass is over Scandinavia, but it is also over the north of Great Britain and is likely to spread south over the whole island by the end of [Thursday]."

It developed into something more than we'd ever seen before... it was, yeah, a little bit frightening
Capt Eric Moody, who piloted a 747 through a volcanic dust cloud

Read more here

The plume is so high that it will neither be visible nor pose a threat to the health of humans on the ground, although Dr Rothery added that we may have a "spectacularly red sunset" on Thursday evening.

The major concern is that the ash could pose a very serious hazard to aircraft engines. The latest maps showing the spread of the volcanic ash cloud can be found here.

Dr Dougal Jerram, an earth scientist at the University of Durham, UK, explained: "Eruptions which are charged with gas start to froth and expand as they reach the surface.

"This results in explosive eruptions and this fine ash being sent up into the atmosphere.

"If it is ejected high enough, the ash can reach the high winds and be dispersed around the globe, for example, from Iceland to Europe. These high winds are exactly where the aeroplanes cruise."

Emergency developments

Airports operator BAA confirmed that all flights at Heathrow, Stansted and Gatwick would be suspended from midday.

"Air traffic restrictions have very properly been applied," said Dr Rothery. "If volcanic ash particles are ingested into a jet engine, they accumulate and clog the engines with molten glass."
Graphic showing effects of volcanic ash on a jet engine

In 1982, British Airways and Singapore Airways jumbo jets lost all their engines when they flew into an ash cloud over Indonesia.

Reports said that the ash sandblasted the windscreen and clogged the engines, which only restarted when enough of the molten ash solidified and broke off.

A KLM flight had a similar experience in 1989 over Alaska.

Stewart John, a fellow of the Royal Academy of Engineering and former president of the Royal Aeronautical Society, explained that the ash can cause severe damage.

"This dust really is nasty stuff," he told BBC News. "It's extremely fine and if it gets into a jet engine, it blocks up all of the ventilation holes that bleed in cooling air.

"Jet engines operate at about 2,000C, and the metals can't take that. The engine will just shut down."

In the case of the 1982 British Airways flight, Mr John explained, when the plane emerged from the cloud, the pilot repeatedly tried and failed to restart the engines.

"They were going down and down, and had just about accepted that they would have to ditch.

"But, at the last minute, one engine started. By repeatedly turning the engine over and having a clean airflow going through, he managed to blow the ash out."

Dr Rothery explained that as a result of those incidents, emergency procedure manuals for pilots were changed.

"Previously, when engines began to fail the standard practice had been to increase power. This just makes the ash problem worse," he said.

"Nowadays, a pilot will throttle back and lose height so as to drop below the ash cloud as soon as possible. The inrush of cold, clean air is usually enough to shatter the glass and unclog the engines.

"Even so, the forward windows may have become so badly abraded by ash that they are useless, and the plane has to land on instruments."

Mr John concluded: "We do not know how long this will last.

"It's like a typhoon - because you can't fly through it, you can't directly monitor it, so we have rely on satellite images and to err on the side of extreme caution."
Height comparison graphic