Accessibility and enzymatic degradation of native and model cellulose substrates

This thesis investigated two issues relevant to the bioconversion of lignocellulosic biomass. The first part relates to the accessibility of cellulose in wood, more specifically, the impact of initial drying on wood ultrastructure. The second part of this thesis pertains to the enzymatic hydrolysis of cellulose, including a characterization of a model film of amorphous cellulose and its subsequent utilization in a fundamental evaluation of the mechanism of cellulase action. In addition, the impact of cellulase treatment on the properties and the morphology of wood pulp fibers was evaluated. The impact of drying on the ultrastructure of fresh wood was studied by deuterium exchange coupled with FT-IR analysis. Initially, the experimental concept and its reliability were evaluated using fresh wood samples. The same experimental concept was then applied to study the impact of initial drying on wood pulps of different characteristics and composition. The objective was to correlate the trends in drying-induced alterations observed for wood and for pulps, bleached chemical pulp in particular. Drying-induced alterations of a native wood sample exhibited a remarkable similarity to those observed for wood pulp samples. The results suggest that the supramolecular rearrangements in the native wood matrix upon dehydration are qualitatively identical to the well-known changes occurring in pulp fibers after drying, although the changes are considerably different in quantity. Quantitative studies of cellulose degradation by cellulase enzymes were carried out using an amorphous cellulose model film with well-defined characteristics. First, the films were extensively characterized, particularly their crystalline nature and swelling behavior. The film swelled excessively in water, doubling its thickness, but returned to the original thickness upon water removal, while retaining its amorphous nature. This film was then used as a substrate in studying the action of monocomponent endoglucanase (EG) that acts on amorphous cellulose. The study was carried out using a quartz crystal microbalance with dissipation monitoring (QCMD). The main objectives were to study the impact of film thickness on the rate of hydrolysis and to directly quantify the extent of hydrolysis (decrease in thickness of films after hydrolysis). It was demonstrated that the amount of substrate available for hydrolysis did not have an impact on the rate of hydrolysis. The investigation also demonstrated impacts of various factors on the kinetic evaluation of the cellulase action. The investigation of the action of a commercial celobiohydrolase on wood pulp fibers showed that the treatment had no significant impact on the strength properties of the pulp. Changes of fiber morphology and of fracture type in the treated fibers during zero span evaluation

X-Ray Kay

http://deepblue.lib.umich.edu/bitstream/2027.42/91009/1/suchyky_1334766956.pd

PRARANCANGAN PABRIK BIODIESEL DARI REFINED, BLEACHED, AND DEODORIZED PALM OIL (RBDPO) DENGAN KAPASITAS PRODUKSI 13.000 TON/TAHUN

ABSTRAKPrarancangan pabrik biodiesel ini menggunakan RBDPO sebagai bahan baku utama. Kapasitas produksi pabrik biodiesel ini adalah 13.000 ton/tahun dengan hari kerja 330 hari/tahun. Bentuk perusahaan yang direncanakan adalah Perseroan Terbatas (PT) dengan menggunakan metode struktur organisasi garis dan staf. Kebutuhan tenaga kerja untuk menjalankan perusahaan ini berjumlah 160 orang. Lokasi pabrik direncanakan didirikan di Aceh Singkil, tepatnya di Desa Tanah Merah, Kecamatan Gunung Meriah, dengan luas tanah 26.400 m2. Sumber air pabrik biodiesel ini berasal dari Sungai Singkil, Kabupaten Aceh Singkil dan untuk memenuhi kebutuhan listrik diperoleh dari Perusahaan Listrik Negara (PLN) dan generator dengan daya 11.885,13 kW.Hasil analisa ekonomi yang diperoleh adalah sebagai berikut: 1.Fixed Capital Investment= Rp 196.649.421.896,-2.Working Capital Investment= Rp34.702.839.158,-3.Total Capital Investment= Rp 231.352.261.054,-4.Total Biaya Produksi= Rp 346.928.832.367,-5.Hasil Penjualan= Rp 444.041.551.680,-,-6.Laba bersih= Rp 72.834.539.485,-7.Pay Out Time (POT) = 4 tahun 3 bulan 8.ROR= 31,48%9.IRR= 24,88%10.Break even Point (BEP)= 29,72% ABSTRACTThis preliminary of biodiesel factory design use RBDPO as a raw material with capacity of production is 13.000 ton/year with work days 330 day per year. Form of this company is Limited Liability Company (Ltd) with structure method line and staff, with total of employees 160 people. The factory location was plans in Aceh Singkil, precisely in Tanah Merah village, Gunung Meriah district with a land area of 26.400 m2. Water sources of this factory obtain from Singkil river in Aceh Singkil and for electricity supply obtain for National Electricty Power Company and Generator with power 11.885,13 kW.From economic analysis was obtained :1.Fixed Capital Investment= Rp. 196.649.421.896,-2.Working Capital Investment= Rp. 34.702.839.158,-3.Total Capital Investment= Rp. 231.352.261.054,-4.Total Production Cost= Rp. 346.928.832.367,-5.Sales Prices= Rp. 444.041.551.680,-6.Profit= Rp. 72.834.539.485,-7.Pay Out Time (POT) = 4 tahun 3 bulan 8.ROR= 31,48%9.IRR= 24,88%10.Break even Point (BEP)= 29,72

Tree Deletion Set has a Polynomial Kernel (but no OPT^O(1) approximation)

In the Tree Deletion Set problem the input is a graph G together with an integer k. The objective is to determine whether there exists a set S of at most k vertices such that G-S is a tree. The problem is NP-complete and even NP-hard to approximate within any factor of OPT^c for any constant c. In this paper we give a O(k^4) size kernel for the Tree Deletion Set problem. To the best of our knowledge our result is the first counterexample to the "conventional wisdom" that kernelization algorithms automatically provide approximation algorithms with approximation ratio close to the size of the kernel. An appealing feature of our kernelization algorithm is a new algebraic reduction rule that we use to handle the instances on which Tree Deletion Set is hard to approximate