Dynamical model for the formation of patterned deposits at receding contact lines

We describe the formation of deposition patterns that are observed in many different experiments where a three-phase contact line of a volatile nanoparticle suspension or polymer solution recedes. A dynamical model based on a long-wave approximation predicts the deposition of irregular and regular line patterns due to self-organised pinning-depinning cycles corresponding to a stick-slip motion of the contact line. We analyze how the line pattern properties depend on the evaporation rate and solute concentration

Dynamical model for the formation of patterned deposits at receding contact lines

We describe the formation of deposition patterns that are observed in many different experiments where a three-phase contact line of a volatile nanoparticle suspension or polymer solution recedes. A dynamical model based on a long-wave approximation predicts the deposition of irregular and regular line patterns due to self-organized pinning-depinning cycles corresponding to a stick-slip motion of the contact line. We analyze how the line pattern properties depend on the evaporation rate and solute concentration

Modelling the formation of structured deposits at receding contact lines of evaporating solutions and suspensions

When a film of a liquid suspension of nanoparticles or a polymer solution is deposited on a surface, it may dewet from the surface and as the solvent evaporates the solute particles/polymer can be deposited on the surface in regular line patterns. In this paper we explore a hydrodynamic model for the process that is based on a long-wave approximation that predicts the deposition of irregular and regular line patterns. This is due to a self-organised pinning–depinning cycle that resembles a stick–slip motion of the contact line. We present a detailed analysis of how the line pattern properties depend on quantities such as the evaporation rate, the solute concentration, the Péclet number, the chemical potential of the ambient vapour, the disjoining pressure, and the intrinsic viscosity. The results are related to several experiments and to depinning transitions in other soft matter systems

KOMBINASI ZPT EKSTRAK BAWANG MERAH DAN PUPUK KOTORAN AYAM TERHADAP PERTUMBUHAN DAN HASIL TANAMAN PAKCOY (Brassica chinensis L.)

Pakcoy (Brassica rapa L.) merupakan salah satu jenis tanaman sayuran yang termasuk dalam famili Brassicaceae. Tanaman pakcoy berasal dari China dan telah banyak dibudidayakan setelah abad ke-5 di China Selatan dan Tengah serta Taiwan. Ekstrak bawang merah mengandung zat pengatur tumbuh yang berperan sebagai hormon auksin. Hormon auksin paling aktif untuk berbagai tanaman dan berperan penting dalam mendorong pertumbuhan yang optimal. Pupuk organik dibedakan menjadi dua, yaitu pupuk organik padat dan cair. Salah satu alternatif pupuk organik padat, adalah kotoran ayam. Penelitian ini bertujuan untuk mengetahui pengaruh ZPT ekstrak bawang merah dan kotoran ayam terhadap pertumbuhan dan hasil tanaman pakcoy (Brassica rappa L). Penelitian ini akan dilaksanakan di Pondok Sentosa No. 27 Aek Nabara dengan ketinggian tempat ± 27 meter di atas permukaan laut. Rancangan yang digunakan adalah Rancangan Acak Kelompok (RAK) faktorial dengan 9 perlakuan dan 3 ulangan. Hasil penelitian menunjukkan bahwa dosis kombinasi ekstrak bawang merah dan kotoran ayam berpengaruh nyata terhadap parameter berat kering dengan perlakuan ekstrak bawang merah 20-40% (2,08 g) dan perlakuan pupuk kotoran ayam dengan dosis 158-316 g/polybag (2,08 g) sedangkan parameter tinggi tanaman, jumlah daun dan berat basah tidak berpengaruh nyata pada kedua perlakuan dan tidak berpengaruh nyata terhadap interaksi kedua faktor perlakuan

Decomposition driven interface evolution for layers of binary mixtures: I. Model derivation and stratified base states

A dynamical model is proposed to describe the coupled decomposition and profile evolution of a free surface film of a binary mixture. An example is a thin film of a polymer blend on a solid substrate undergoing simultaneous phase separation and dewetting. The model is based on model-H describing the coupled transport of the mass of one component (convective Cahn-Hilliard equation) and momentum (Navier-Stokes-Korteweg equations) supplemented by appropriate boundary conditions at the solid substrate and the free surface. General transport equations are derived using phenomenological non-equilibrium thermodynamics for a general non-isothermal setting taking into account Soret and Dufour effects and interfacial viscosity for the internal diffuse interface between the two components. Focusing on an isothermal setting the resulting model is compared to literature results and its base states corresponding to homogeneous or vertically stratified flat layers are analysed.Comment: Submitted to Physics of Fluid

Thin film evolution equations from (evaporating) dewetting liquid layers to epitaxial growth

In the present contribution we review basic mathematical results for three physical systems involving self-organising solid or liquid films at solid surfaces. The films may undergo a structuring process by dewetting, evaporation/condensation or epitaxial growth, respectively. We highlight similarities and differences of the three systems based on the observation that in certain limits all of them may be described using models of similar form, i.e., time evolution equations for the film thickness profile. Those equations represent gradient dynamics characterized by mobility functions and an underlying energy functional. Two basic steps of mathematical analysis are used to compare the different system. First, we discuss the linear stability of homogeneous steady states, i.e., flat films; and second the systematics of non-trivial steady states, i.e., drop/hole states for dewetting films and quantum dot states in epitaxial growth, respectively. Our aim is to illustrate that the underlying solution structure might be very complex as in the case of epitaxial growth but can be better understood when comparing to the much simpler results for the dewetting liquid film. We furthermore show that the numerical continuation techniques employed can shed some light on this structure in a more convenient way than time-stepping methods. Finally we discuss that the usage of the employed general formulation does not only relate seemingly not related physical systems mathematically, but does as well allow to discuss model extensions in a more unified way

Modelling approaches to the dewetting of evaporating thin films of nanoparticle suspensions

We review recent experiments on dewetting thin films of evaporating colloidal nanoparticle suspensions (nanofluids) and discuss several theoretical approaches to describe the ongoing processes including coupled transport and phase changes. These approaches range from microscopic discrete stochastic theories to mesoscopic continuous deterministic descriptions. In particular, we describe (i) a microscopic kinetic Monte Carlo model, (ii) a dynamical density functional theory and (iii) a hydrodynamic thin film model. Models (i) and (ii) are employed to discuss the formation of polygonal networks, spinodal and branched structures resulting from the dewetting of an ultrathin ‘postcursor film’ that remains behind a mesoscopic dewetting front. We highlight, in particular, the presence of a transverse instability in the evaporative dewetting front, which results in highly branched fingering structures. The subtle interplay of decomposition in the film and contact line motion is discussed. Finally, we discuss a simple thin film model (iii) of the hydrodynamics on the mesoscale. We employ coupled evolution equations for the film thickness profile and mean particle concentration. The model is used to discuss the self-pinning and depinning of a contact line related to the ‘coffee-stain’ effect. In the course of the review we discuss the advantages and limitations of the different theories, as well as possible future developments and extensions

Laporan Praktek Kerja Lapangan (PKL) di RW 8 Kelurahan Rangkah Kecamatan Tambaksari Kota Surabaya

RW 8 Kelurahan Rangkah berada di Kecamatan Tambaksari Kota Surabaya Provinsi Jawa Timur. Total luas wilayah 70 hektar. Mayoritas penduduk RW 8 Kelurahan Rangkah berprofesi sebagai pedagang dan karyawan swasta. Berdasarkan analisis data diperoleh hasil dari penyebaran kuesioner di 8 RT dengan jumlah sampel 250 kepala keluarga yang diperoleh dengan metode simple random sampling, observasi, focus grup discussion (FGD), wawancara mendalam (indepth interview) kepada masyarakat sekaligus perangkat desa, dan studi kasus (case study). Data sekunder diperoleh dari Data Puskesmas Rangkah dan Profil Kelurahan Rangkah. Hasil analisis data didapatkan beberapa masalah terkait pemberian ASI Ekslusif rendah, pemberian MP-ASI kurang dari 6 bulan, adanya kasus Tuberculosis, kepemilikan septictank rendah dan pemberantasan sarang nyamuk yang dilakukan mandiri (oleh diri sendiri) rendah. Beberapa permasalahan tersebut diprioritaskan menggunakan metode USG dan didapatkan dari perhitungan metode USG adalah masalah kasus Tuberculosis. Selanjutnya dalam pencairan akar penyebab masalah kami menggunakan metode Fishbone, dan penentuan alternative solusi menggunakan metode MERR. Hasil dari perhitungan MEER diperoleh bahwa prioritas alternative solusi yang ditetapkan adalah sosialisasi kepada masyarakat terkait pencegahan dan penanggulangan penyakit Tuberkulosis. Intervensi yang akan dilakukan dikenal dengan KECEBUR RANGKAH (Kita Cegah Tuberkulosis Bersama Dulur Rangkah). Intervensi tersebut bertujuan agar masyarakat mampu dan mau melakukan pencegahan dan penanggulangan penyakit Tuberkulosis dengan tujuan khusus yang meliputi peningkatan pengetahuan masyarakat terkait penyakit Tuberkulosis. Sasaran dari program KECEBUR RANGKAH adalah masyarakat RW 8 Kelurahan Rangkah. Beberapa kegiatan dalam program KECEBUR RANGKAH dapat terlaksana dengan lancar meskipun terdapat beberapa kendala. Kegiatan tersebut meliputi pembentukan kader TB, pelatihan pengisian form skrining awal Tuberkulosis dan penyuluhan / sosialisasi mengenai penyakit Tuberkulosis

Transport and deposition patterns in drying sessile droplets

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/106826/1/aic14338.pd