Pilot-scale production of polylactic acid nanofibers by melt electrospinning

Melt electrospinning has been used to manufacture fibers with diameters in the low micrometer range, but the production of submicrometer fibers has proven more challenging. In this study, we investigated the feasibility of fabricating polylactic acid nanofibers using polymer grades with the increasing melt flow rates (15–85 g/10 min at 210°C) by melt electrospinning with a 600-nozzle pilot-scale device featuring an integrated climate control system realized as a glass chamber around the spinneret. Previous experiments using this device without appropriate climate control produced fibers exceeding 1 µm in diameter because the drawing of fibers was inhibited by the rapid cooling of the polymer melt. The integrated glass chamber created a temperature gradient exceeding the glass transition temperature of the polymer, which enhanced the drawing of fibers below the spinneret. An average fiber diameter of 810 nm was achieved using Ingeo Biopolymer 6252, and the finest individual fiber (420 nm in diameter) was produced at a spin pump speed of 5 rpm and a spinneret set temperature of 230°C. We have therefore demonstrated the innovative performance of our pilot-scale melt-electrospinning device, which bridges the gap between laboratory-scale and pilot-scale manufacturing and achieves fiber diameters comparable to those produced by conventional solution electrospinning.

Global Warming and Biodiversity

Some natural and some artificial activities are responsible for global warming, which is not only affecting the environment but also humans at an alarming rate. The effects of global warming are seen in growing biodiversity. There are many greenhouse gases, which form a thin layer in the atmosphere making the Earth's surface warmer day by day. The presence of carbon dioxide, methane, nitrous oxide, and water vapors are responsible for global warming. Global warming behaves like greenhouse in which a glass chamber is incorporated that allows the sunrays to pass inside the chamber but does not allow reflecting back from the glass. Due to this, the inside temperature of the chamber becomes hotter in comparison to the outside temperature. The maintenance of the temperature inside the chamber helps plant growth.

UJI EFEKTIVITAS EKSTRAK BUAH LEUNCA (SOLANUM NIGRUM L.) SEBAGAI INSEKTISIDA TERHADAP NYAMUK AEDES AEGYPTI DAN ANOPHELES ACONITUS

Nyamuk Aedes aegypti dan Anopheles aconitus merupakan beberapa vektor penting pada penyakit tropis di Indonesia, antara lain seperti penyakit demam berdarah dan malaria. Salah satu cara pemberantasan nyamuk yang paling sering digunakan adalah dengan menggunakan insektisida. Penggunaan insektisida kimiawi yang bertujuan untuk membunuh nyamuk dewasa juga menimbulkan permasalahan tersendiri yaitu timbulnya resistensi nyamuk dan efek toksik pada manusia. Oleh karena itu, diperlukan insektisida alternatif yang lebih aman terhadap lingkungan yang berasal dari tanaman. Salah satunya dengan menggunakan ekstrak buah Leunca (Solanum nigrum). Buah Leunca mengandung glikoalkaloid yang beracun. Penelitian ini bertujuan untuk membuktikan ekstrak buah Leunca mempunyai potensi sebagai insektisida alami terhadap nyamuk Aedes aegypti dan Anopheles aconitus. Penelitian ini merupakan penelitian eksperimental laboratoris dengan rancangan true experimental-post test only control group design. Sampel yang digunakan adalah nyamuk Aedes aegypti dengan konsentrasi ekstrak 20%, 40%, 60%, dan 80% dan nyamuk Anopheles aconitus dengan konsentrasi ekstrak 5%, 10%, 20% dan 40%. Dilakukan penyemprotan pada glass chamber kemudian diamati sampai 20 menit, setelah itu nyamuk dipindah ke dalam paper cup dan diamati selama 24 jam. Pengulangan dilakukan sebanyak empat kali. Uji yang digunakan adalah uji Oneway Anova dengan nilai p < 0,05 dan analisis probit.Hasil uji Oneway Anova diperoleh nilai signifikansi < 0,05. Hasil penelitian menunjukkan bahwa ekstrak buah Leunca memiliki efek insektisida terhadap nyamuk Aedes aegypti dan Anopheles aconitus. Hasil analisis probit nyamuk Aedes aegypti LC50 terletak antara 69,890% dan 156,417% dengan estimasi 91,128% dan LC90 terletak antara 337,934% dan 5842,532% dengan estimasi 785,398%, sedangkan nyamuk Anopheles aconitus LC50 terletak antara 19,809% dan 33,570%. Dengan estimasi 24,767% dan LC90 terletak antara 96,540% dengan 450,875% dengan estimasi 169,046%. Peneliti menyimpulkan bahwa ekstrak buah Leunca (Solanum nigrum L.) memiliki efek insektisida terhadap nyamuk Aedes aegypti dengan konsentrasi 80% dan Anopheles aconitus dengan konsentrasi 40%.Kata Kunci: Ekstrak buah Leunca (Solanum nigrum), insektisida, Aedes aegypti, Anopheles aconitus

Motion and Deformation of a Water Droplet Under the Influence of an Electric Field

Due to its molecular polarity, a water droplet suspended in a dielectric medium experiences a force under the influence of an electric field. However, unlike a charged rigid particle, a water droplet undergoes a significant deformation due to its liquid state. Thus, the dynamic behavior of the water droplet cannot be fully analyzed without accounting for the interaction between the electric and fluid fields. In an effort to broaden our understanding of this phenomenon, a parallel plate electrode system was constructed inside a glass chamber. A water droplet was suspended in the glass chamber filled with insulated oil. After applying a high voltage across the plates, the droplet motion was recorded with a camera and analyzed using an image processing program. The effects of several parameters including, droplet size, droplet conductivity, and initial droplet position were investigated. Results obtained from this investigation help gain a better understanding of the droplet deformation and breakup mechanisms spanning several fields, some of which include oil-water separation, electrocoalescence, and electrospraying.