Droplet activation, separation, and compositional analysis: laboratory studies and atmospheric measurements [Discussion paper]

Droplets produced in a cloud condensation nucleus chamber as a function of supersaturation have been separated from unactivated aerosol particles using counterflow virtual impaction. Residual material after droplets were evaporated was chemically analyzed with an Aerodyne Aerosol Mass Spectrometer and the Particle Analysis by Laser Mass Spectrometry instrument. Experiments were initially conducted to verify activation conditions for monodisperse ammonium sulfate particles and to determine the resulting droplet size distribution as a function of supersaturation. Based on the observed droplet size, the counterflow virtual impactor cut-size was set to differentiate droplets from unactivated interstitial particles. Validation experiments were then performed to verify that only droplets with sufficient size passed through the counterflow virtual impactor for subsequent analysis. A two-component external mixture of monodisperse particles was also exposed to a supersaturation which would activate one of the types (ammonium sulfate) but not the other (polystyrene latex spheres). The mass spectrum observed after separation indicated only the former, validating separation of droplets from unactivated particles. Results from atmospheric measurements using this technique indicate that aerosol particles often activate predominantly as a function of particle size. Chemical composition is not irrelevant, however, and we observed enhancement of sulfate in droplet residuals using single particle analysis

Formulasi dan Stabilitas Mikroemulsi O/W dengan Metode Emulsifikasi Spontan Menggunakan VCO dan Minyak Sawit sebagai Fase Minyak: Pengaruh Rasio Surfaktan-Minyak

Penelitian ini bertujuan untuk (1) formulasi mikroemulsi o/w dengan variasirasio surfaktan-minyak, (2) menentukan stabilitas mikroemulsiterhadap sentrifugasi, pemanasan dan penyimpanan suhu ruang, dan (3) karakterisasi mikroemulsi dengan stabilitas terbaik. Mikroemulsi dibuat menggunakan campuran tiga surfaktan food grade yaitu surfaktan HLB rendah (span 80), sedang (span 20 atau span 40), dan tinggi (tween 80), dengan rasio surfaktan minyak 2, 3, 4 dan 5. VCO dan minyak kelapa sawit digunakan sebagai fase minyak, 10 μM bufer fosfat pH 7 sebagai fase aqueous. Mikroemulsi o/w terbentuk pada rasio surfaktan minyak 3 atau lebih untuk penggunaan VCO dan pada rasio surfaktan minyak yang lebih tinggi (yaitu 4 atau 5) untuk penggunaan minyak sawit sebagai fase minyak. Mikroemulsi dengan fase minyak VCO yang stabil terhadap sentrifugasi, pemanasan maupun penyimpanan suhu ruang adalah mikroemulsi dengan rasio surfaktan-minyak 4 atau 5, sedangkan penggunaan minyak sawit sebagai fase minyak menghasilkan mikroemulsi yang stabil pada rasio surfaktan-minyak 4. Mikroemulsi dengan rasio surfaktan-minyak 4 memperlihatkan stabilitas terbaik. Mikroemulsi tersebut memiliki distribusi ukuran partikel monomodal, rerata diameter partikel dan viskositas mencapai 21,7 ± 0,02nm dan 6,0 ± 0,10cp (VCO), 22,9 ± 0,15nm dan 6,2 ± 0,05cp (minyak sawit)

Sifat Prooksidatif Fortifikan NaFeEDTA Dan Fe-SULFAT Pada Kecap Hasil Fortifikasi

Iron in iron-fortified soy sauce may have oxidative effect in both oil and amino acids or protein component. In order to evaluate the possible oxidative properties of both NaFeEDTA and FeSO fortificants, a study of oxidation in soy sauce fortified with the fortificants was conducted. Level of fortificant was 266 mg Fe/L of soy sauce. The extent of oxidation was measured by the level of peroxide value and TBARS value of oil component of fortified soy sauce, as well as car- bonyls content of soy sauce model. The effect of H O addition on level of oxidation was also evaluated. It was found that in soy sauce fortified with either NaFeEDTA or FeSO , the fortificants did not promote oxidation of oil and amino acids components. However, addition of H O made peroxide value, TBARS value, and carbonyls content of fortified samples increased

Kandungan Gizi, Rendemen Tepung, dan Kadar Fenol Total Alpukat (Persea Americana, Mill) Varietas Ijo Panjang dan Ijo Bundar

Penelitian ini bertujuan untuk mengetahui proporsi daging buah, rendemen tepung, kandungan gizi dan fenol total alpukat varietas Ijo Panjang dan Ijo Bundar. Pemilihan kedua varietas tersebut karena merupakan varietas unggul dan direkomendasikan untuk dikembangkan di Indonesia. Kandungan, air, karbohidat, protein, lemak dan abu dilakukan dengan analisis proksimat (AOAC), kandungan vitamin A dan E dengan metode spektrofotometri dan vitamin C dengan metode titrasi, analisis mineral dengan metode AAS. Total fenol dianalisis dengan metode Folin-Ciocalteu. Hasil penelitian menunjukan bahwa proporsi daging buah, kadar air, seng varietas Ijo Panjang lebih tinggi dibandingkan Ijo Bundar. Rendemen tepung alpukat lebih tinggi pada varietas Ijo Bundar. Kandungan protein, lemak, abu, vitamin (A,E dan C), mineral (Fe, Na, K, P) lebih tinggi pada varietas Ijo Bundar. Kandungan magnesium dan mangan tidak terdapat perbedaan signifikan kedua varietas. Fenol total daging buah dan tepung alpukat lebih tinggi pada varietas Ijo Bundar dibandingkan Ijo Panjang

Droplet activation, separation, and compositional analysis: laboratory studies and atmospheric measurements

Droplets produced in a cloud condensation nuclei chamber (CCNC) as a function of supersaturation have been separated from unactivated aerosol particles using counterflow virtual impaction. Residual material after droplets were evaporated was chemically analyzed with an Aerodyne Aerosol Mass Spectrometer (AMS) and the Particle Analysis by Laser Mass Spectrometry (PALMS) instrument. Experiments were initially conducted to verify activation conditions for monodisperse ammonium sulfate particles and to determine the resulting droplet size distribution as a function of supersaturation. Based on the observed droplet size, the counterflow virtual impactor cut-size was set to differentiate droplets from unactivated interstitial particles. Validation experiments were then performed to verify that only droplets with sufficient size passed through the counterflow virtual impactor for subsequent analysis. A two-component external mixture of monodisperse particles was also exposed to a supersaturation which would activate one of the types (hygroscopic salts) but not the other (polystyrene latex spheres or adipic acid). The mass spectrum observed after separation indicated only the former, validating separation of droplets from unactivated particles. Results from ambient measurements using this technique and AMS analysis were inconclusive, showing little chemical differentiation between ambient aerosol and activated droplet residuals, largely due to low signal levels. When employing as single particle mass spectrometer for compositional analysis, however, we observed enhancement of sulfate in droplet residuals

Physics Opportunities with Meson Beams

Over the past two decades, meson photo- and electro-production data of unprecedented quality and quantity have been measured at electromagnetic facilities worldwide. By contrast, the meson-beam data for the same hadronic final states are mostly outdated and largely of poor quality, or even nonexistent, and thus provide inadequate input to help interpret, analyze, and exploit the full potential of the new electromagnetic data. To reap the full benefit of the high-precision electromagnetic data, new high-statistics data from measurements with meson beams, with good angle and energy coverage for a wide range of reactions, are critically needed to advance our knowledge in baryon and meson spectroscopy and other related areas of hadron physics. To address this situation, a state of-the-art meson-beam facility needs to be constructed. The present paper summarizes unresolved issues in hadron physics and outlines the vast opportunities and advances that only become possible with such a facility.Comment: 46 pages, 10 figures, 4 table

Experimental Signature of Medium Modifications for rho and omega Mesons in the 12 GeV p + A Reactions

The invariant mass spectra of e+e- pairs produced in 12-GeV proton-induced nuclear reactions are measured at the KEK Proton-Synchrotron. On the low-mass side of the omega meson peak, a significant enhancement over the known hadronic sources has been observed. The mass spectra, including the excess, are well reproduced by a model that takes into account the density dependence of the vector meson mass modification, as theoretically predicted.Comment: 4 pages, 3 figures, Version accepted for Physical Review Lette