EKSTRAKSI PEKTIN DARI AMPAS NANAS

Abstrak Buah nanas setelah panen akan cepat mengalami kerusakan karena tingginya kandungan air yang ada pada buah. Untuk mengatasi masalah panen raya agar harga buah tidak turun maka pemanfaatan nanas sebaiknya ditingkatkan untuk diambil pektinnya mengingat pektin masih diimport dari luar negeri untuk kebutuhan dalam negeri. Pektin adalah bahan pengental alami yang berasal dari buah dan beberapa macam tumbuhan. Adapun penggunaan pektin dalam industri pangan adalah sebagai bahan pengental, bahan tambahan pada pembuatan selai, jelly dan marmalade. Tujuan dari penelitian ini adalah untuk mengambil pektin yng terkandung dalam buah nanas dengan cara ekstraksi menggunakan pelarut asam sulfat (H2SO4). Adapun cara perolehan pektin tersebut dilakukan dengan menimbang ampas buah nanas sebanyak 10 gram yang dilarutkan dalam 100 cc aquadest, kemudian dicampur dengan asam sulfat sebagai bahan pelarut dengan konsentrasi 0,2 N pada volume (4 (pH=4), 9 (pH=3), 14 (pH=1,8), 19 (pH=1,5), 24 (pH=1,2) (cc)) dan suhu operasi 90 °C pada waktu ekstraksi (0, 30, 60, 90, 120 (menit)) dengan kecepatan pengadukan 300 rpm, kemudian dilakukan pengendapan dengan penambahan etanol dan yang terakhir adalah pencucian dan pengeringan dengan menggunakan oven. Hasil penelitian menunjukkan bahwa kondisi operasi terbaik dicapai pada waktu ekstraksi 120 menit, pH ekstraksi adalah 1,2 dengan berat pektin yang dihasilkan sebanyak 0,3681 gram. Kata kunci : Nanas, Ekstraksi, Pekti

MHD Flow and Heat Transfer in a Power-law Liquid Film at a Porous Surface in the Presence of Thermal Radiation

In this paper, the effects of variable thermal conductivity and thermal radiation on the MHD flow and heat transfer of a non-Newtonian power-law liquid film at a horizontal porous sheet in the presence of viscous dissipation is studied. The governing time dependent boundary layer equations are transformed to coupled, non-linear ordinary differential equations with power-law index, unsteady parameter, film thickness, magnetic parameter, injection parameter, variable thermal conductivity parameter, thermal radiation parameter, the Prandtl number and the Eckert number. These coupled non-linear equations are solved numerically by an implicit, finite difference scheme known as the Keller box method. The obtained numerical results for velocity and temperature profiles are presented graphically. Also, the obtained results of our study for some special cases are compared with the previously published results, and the results are found to be in very good agreement. The effects of unsteady parameter on the skin friction, wall-temperature gradient and the film thickness are explored for different values of the power-law index and the magnetic parameter. The results obtained reveal many interesting behaviors that warrant further study of the equations related to non-Newtonian fluid phenomena, especially the shear-thinning phenomena

Reducing the environmental impact of surgery on a global scale: systematic review and co-prioritization with healthcare workers in 132 countries

Abstract Background Healthcare cannot achieve net-zero carbon without addressing operating theatres. The aim of this study was to prioritize feasible interventions to reduce the environmental impact of operating theatres. Methods This study adopted a four-phase Delphi consensus co-prioritization methodology. In phase 1, a systematic review of published interventions and global consultation of perioperative healthcare professionals were used to longlist interventions. In phase 2, iterative thematic analysis consolidated comparable interventions into a shortlist. In phase 3, the shortlist was co-prioritized based on patient and clinician views on acceptability, feasibility, and safety. In phase 4, ranked lists of interventions were presented by their relevance to high-income countries and low–middle-income countries. Results In phase 1, 43 interventions were identified, which had low uptake in practice according to 3042 professionals globally. In phase 2, a shortlist of 15 intervention domains was generated. In phase 3, interventions were deemed acceptable for more than 90 per cent of patients except for reducing general anaesthesia (84 per cent) and re-sterilization of ‘single-use’ consumables (86 per cent). In phase 4, the top three shortlisted interventions for high-income countries were: introducing recycling; reducing use of anaesthetic gases; and appropriate clinical waste processing. In phase 4, the top three shortlisted interventions for low–middle-income countries were: introducing reusable surgical devices; reducing use of consumables; and reducing the use of general anaesthesia. Conclusion This is a step toward environmentally sustainable operating environments with actionable interventions applicable to both high– and low–middle–income countries

Mhd Mixed Convection Flow Over A Permeable Non-Isothermal Wedge

Numerical solutions are obtained for the hydro-magnetic mixed convection boundary layer flow of an electrically conducting fluid over a non-isothermal wedge in the presence of variable thermal conductivity. The effects due to viscous dissipation, internal heat generation/absorption, thermal radiation, Joule heating and stress work are included. The governing partial differential equations of the problem, subjected to the appropriate boundary conditions are solved numerically by an efficient finite difference scheme. Numerical calculations are carried out for several sets of values of the dimensionless parameters and a careful study of the results obtained reveal that the flow field is influenced appreciably by the applied magnetic field in addition to the other parameters. Numerical results for the velocity and temperature fields, the local skin-friction coefficient and the local Nusselt number are presented graphically and discussed. To validate the numerical method, comparisons are made with the available results in the literature as special cases and the results are found to be in good agreement. The results obtained reveal many interesting behaviors that warrant further study of the flow and heat transfer characteristics over the permeable wedge. © 2013

Hydromagnetic Fluid Flow And Heat Transfer At A Stretching Sheet With Fluid-Particle Suspension And Variable Fluid Properties

In this paper, we investigate the influence of temperature-dependent fluid properties on the flow and heat transfer characteristics of an electrically conducting dusty fluid over a stretching sheet. Temperature-dependent fluid properties are assumed to vary as a function of the temperature. The governing coupled nonlinear partial differential equations along with the appropriate boundary conditions are transformed into coupled, nonlinear ordinary differential equations by a similarity transformation. The resultant coupled highly nonlinear ordinary differential equations are solved numerically by a second order implicit finite difference scheme known as the Keller-Box method. The numerical solutions are compared with the approximate analytical solutions, obtained by a perturbation technique. The analysis reveals that even in the presence of variable fluid properties the transverse velocity of the fluid is to decrease with an increase in the fluid-particle interaction parameter. This observation holds even in the presence of magnetic field. Furthermore, the effects of the physical parameters on the fluid velocity, the velocity of the dust particle, the density of the dust particle, the fluid temperature, the dust-phase temperature, the skin friction, and the wall-temperature gradient are assessed through tables and graphs. © 2012 American Society of Mechanical Engineers

Optimal Homotopy Asymptotic Solutions For Nonlinear Ordinary Differential Equations Arising In Flow And Heat Transfer Due To Nonlinear Stretching Sheet

Optimal homotopy asymptotic method (OHAM) is used to obtain solutions for nonlinear ordinary differential equations (ODEs) arising in fluid flow and heat transfer at a nonlinear stretching sheet. The solutions for skin friction and temperature gradient for some special cases are tabulated and compared with the available numerical results in the literature. Moreover, OHAM is found to be very easy to use and the technique could be used for solving coupled nonlinear systems of ordinary differential equations arising in science and engineering