Synthesis of Polyhedral Magnetite Particles by Hydrothermal Process Under High Pressure Condition

Magnetite particles were successfully generated by hydrothermal synthesis using water at subcritical conditions. By changing the temperature and pressure at subcritical water conditions, the thermodynamics and transport properties of the water can be controlled, thus enabling to manage the way of crystal formation, morphology, and particle size. In this work, the experiments were carried out at temperatures of 250 °C and 290 °C and a pressure of 10 MPa with a reactor made of SUS 316 in a batch system. The synthesized particles were dried in vacuum condition and characterized by SEM and XRD. The XRD patterns showed that magnetite particles were dominantly formed in the particle products with a black color. The results showed that the magnetite particles formed had diameters of around 60 nm in all experiments with irregular polyhedral shaped morphologies

The effect of ultrasound pretreatment on some selected physicochemical properties of black cumin (Nigella Sativa)

Background In the present study, the effects of ultrasound pretreatment parameters including irradiation time and power on the quantity of the extracted phenolic compounds quantity as well as on some selected physicochemical properties of the extracted oils including oil extraction efficiency, acidity and peroxide values, color, and refractive index of the extracted oil of black cumin seeds with the use of cold press have been studied. Methods For each parameter, three different levels (30, 60, and 90 W) for the ultrasound power and (30, 45, and 60 min) and for the ultrasound irradiation time were studied. Each experiment was performed in three replications. Results The achieved results revealed that, with enhancements in the applied ultrasound power, the oil extraction efficiency, acidity value, total phenolic content, peroxide value, and color parameters increased significantly (P 0.05). Conclusions In summary, it could be mentioned that the application of ultrasound pretreatment in the oil extraction might improve the oil extraction efficiency, the extracted oil’s quality, and the extracted phenolic compounds content.info:eu-repo/semantics/publishedVersio

Centrifugal melt spinning of polyvinylpyrrolidone (PVP)/triacontene copolymer fibres

Polyvinylpyrrolidone/1-triacontene (PVP/TA) copolymer fibre webs produced by centrifugal melt spinning were studied to determine the influence of jet rotation speed on morphology and internal structure as well as their potential utility as adsorbent capture media for disperse dye effluents. Fibres were produced at 72 C with jet head rotation speeds from 7000 to 15,000 r min-1. The fibres were characterised by means of SEM, XRD and DSC. Adsorption behaviour was investigated by means of an isothermal bottle point adsorption study using a commercial disperse dye, Dianix AC-E. Through centrifugal spinning nanofibers and microfibers could be produced with individual fibres as fine as 200–300 nm and mean fibre diameters of ca. 1–2 lm. The PVP/TA fibres were mechanically brittle with characteristic brittle tensile fracture regions observed at the fibre ends. DSC and XRD analyses suggested that this brittleness was linked to the graft chain crystallisation where the PVP/TA was in the form of a radial brush copolymer. In this structure, the triacontene branches interlock and form small lateral crystals around an amorphous backbone. As an adsorbent, the PVP/TA fibres were found to adsorb 35.4 mg g-1 compared to a benchmark figure of 30.0 mg g-1 for a granular-activated carbon adsorbent under the same application conditions. PVP/TA is highly hydrophobic and adsorbs disperse dyes through the strong ‘‘hydrophobic bonding’’ interaction. Such fibrous assemblies may have applications in the targeted adsorption and separation of non-polar species from aqueous or polar environments

SIMULASI NUMERIK DEPOSISI AEROSOL PARTIKEL PADA POROUS STRUKTUR BERBASIS COMPUTATIONAL FLUID DYNAMIC (CFD)

Deposisi partikel didalam porous struktur substrate telah dikembangkan aplikasinya sebagai fotokatalitik, membran filter, dan template untuk material pendukung dalam bidang energi dan lingkungan. Penelitian ini bertujuan untuk mendapatkan kondisi optimum pada deposisi aerosol partikel pada substrat yang mempunyai struktur berpori berdasarkan simulasi numerik dengan software Computational Fluid Dynamics (CFD). Metode simulasi berbasis CFD digunakan sebagai alternatif untuk mereduksi beberapa variabel kondisi yang sulit dikontrol. Permodelan dengan menggunakan CFD ini meliputi tiga tahapan proses, yaitu pre-processing, processing, dan post-processing. Dimensi yang akan digunakan pada CFD ini adalah dengan permodelan 2 dimensi, dimana wall memiliki panjang 10 cm dan lebar 2,5 cm. Analisa yang dilakukan meliputi pola gerakan partikel, kecepatan gerakan partikel, dan jumlah partikel pada porous struktur. Variabel yang ditetapkan pada permodelan ini adalah jarak partikel dengan substrat dan diameter pori dari substrat. Sedangkan ukuran partikel dan kecepatan fluida divariasikan. Hasil penelitian menunjukkan bahwa pola alir dan pergerakan partikel sangat ditentukan oleh kecepatan fluida.  Selain itu, semakin kecil partikel yang digunakan maka semakin optimum deposisi yang terjadi, dimana deposisi optimum akan tercapai jika partikel tersebut mempunyai ukuran hingga 36 % dari ukuran pore nya. Deposisi yang optimum juga terjadi jika aliran fluidanya dalam kondisi laminar dan transisi

A multi-scale environmental niche model for the Endangered dhole Cuon alpinus

The dhole Cuon alpinus is a large canid that is categorized as Endangered on the IUCN Red List and at risk of global extinction. Information on the spatial distribution of suitable habitat is important for conservation planning but is largely unavailable. We quantified the spatial distribution of potential range as well as the relative probability of dhole occurrence across large parts of the species’ global range. We used the MaxEnt algorithm to produce a multi-scale environmental niche model based on 24 environmental variables and dhole occurrence data from 12 countries. We identified three regions where dhole conservation should be focused: western India, central India, and across the Himalayan foothills through Southeast Asia. Connectivity between suitable areas was poor, so coordinated action among these regions should be a priority. For instance, transboundary dhole conservation initiatives across the Himalayas from southern China, Myanmar, north-east India, Nepal and Bhutan need to be initiated. We also highlight the value of improving dhole population viability on unprotected land and increasing monitoring in the northern parts of its historic distribution, in particular in areas within mainland China