Birch material procurement in a furniture producing company

Detta examensarbete handlar om hur ett möbelproducerande företags råmaterialförsörjning går till. Företaget som har varit värd för arbetet är ett möbeltillverkande företag som heter Stolab och ligger i Smålandstenar. Studiebesök och intervjuer har hos Stolab och deras leverantörer legat till grund för det arbete som vi har utfört. Ämnen som är behandlade är kvalitetsaspekter på råmaterialet samt hur relationerna mellan kund – leverantör fungerar. Arbetet fokuserar främst på den sista punkten, hur relationerna ser ut mellan kund leverantör, vilka möjligheter man har att förbättra kommunikationen mellan företagen och hur inköp och lagerhållning kan fungera. För att kunna förbättra kvaliteten på det råmaterial som kommer till företaget så är en viktig del i det att öka förståelsen för de krav som ställs. Kraven måste också kommuniceras på ett effektivt sätt. Vi har utarbetat en modell för hur detta samarbete kan gå till samt gett en del andra förslag till åtgärder för att kunna förbättra kvalitet på materialet och förbättra relationerna.This final thesis deals with the hardwood raw material procurement in a furniture producing company. The company that has been our host is a furniture producing company called Stolab situated in Smålandstenar. The study visits and interviews we have completed has been the base of this work and the theory studies that we have made. Subjects that have been treated in this report are quality aspects on the raw material and also the relationships between customer and the supplier. The discussion is focused on the latest mentioned part, which possibilities there are to improve the communication between the companies and how purchase and store-keeping can work. To be able to improve the quality of the raw material that is being delivered to the company an important part is to gain the understanding of the demand that is set. The demands also need to be communicated in an efficient way. We have worked out a model which gives suggestions to motions to be made to improve the quality of the raw material and the relationships between customers and suppliers

QCM-D as a method for monitoring enzyme immobilization in mesoporous silica particles

Enzyme immobilization in mesoporous materials is a field of great interest, with applications in biocatalysis and biosensing. However, the actual immobilization process is not well understood and has mainly been studied by indirect measurements. The present work demonstrates a direct method for real time study of enzyme immobilization in mesoporous silica particles using quartz crystal microbalance with dissipation monitoring (QCM-D). Silica-coated sensors were grafted with amine groups followed by adsorption of small (40 nm), spherical mesoporous silica particles, after which the enzyme immobilization into the mesoporous particles could be studied in real time. The influence of pH on the immobilization efficiency was studied using two different enzymes; lipase from Rhizopus oryzae and feruloyl esterase from Fusarium oxysporum. The results showed that the silica particles adsorbed readily to the amine-grafted surface. The QCM-D measurements indicated that considerably more enzyme was immobilized into mesoporous silica particles than to non-porous silica particles and to a flat silica surface. The viscoelastic effect of the immobilized enzymes was visualized by plotting the frequency shift against the corresponding dissipation. It was observed that the immobilization into the porous particles can be divided into two regimes where the first regime is suggested to represent adsorption to the outer surface and pore openings and the second regime represents further adsorption inside the pores. In summary, we demonstrated QCM-D as a novel method for understanding enzyme immobilization in mesoporous particles in real time and the approach may be of general use for studies of entrapment of molecules into porous particles

Immobilization of feruloyl esterases in mesoporous materials leads to improved transesterification yield

Feruloyl esterases are used in biocatalysis for refinement of hydroxycinnamic acids, a group of compounds with antioxidant and antibacterial properties where modification of solubility is necessary for the compounds to be of interest in different commercial products. In industrially feasible and efficient processes, immobilization of enzymes is often required for sufficient enzyme stability and to enable recovery. In recent years, mesoporous materials have become popular as immobilization support due to advantages such as high protein loading capacity and enhanced enzyme activity because of confinement into pores. We used mesoporous silica, for the first time, as immobilization support for feruloyl esterases. The crude enzyme preparation Depol 740L was adsorbed into two SBA-15 mesoporous silica materials of different pore size and the effects of the immobilization on transesterification of methyl ferulate with 1-butanol into butyl ferulate were studied, tested in a reaction system based on 92.5% 1-butanol and 7.5% MOPS buffer (pH 6.0). Immobilization in mesoporous silica with larger pore size (9 rim) showed higher protein loading and higher specific activity compared to immobilization with smaller pore size (5 nm). Importantly, adsorption into mesoporous silica changed the product specificity of the enzymes to favor transesterification and decrease the rate of hydrolysis compared to free enzymes. The immobilized enzyme had a butyl ferulate yield of up to 90%, significantly higher compared to free enzymes. Additionally, the immobilized enzymes showed an excellent operational stability and reusability. retaining >= 70% of the initial activity after 6 sequential runs, each lasting 6 days. Consequently, we show that mesoporous silica is a robust immobilization support for feruloyl esterases to be used in the development of biocatalysts for customization of the antioxidant properties of hydroxycinnamic acids

A comparison of lipase and trypsin encapsulated in mesoporous materials with varying pore sizes and pH conditions

Immobilized enzymes have an advantage over enzymes free in solution in that they are easily recovered after completed reaction. In addition, immobilization often gives enhanced stability. Entrapment of an enzyme in the pores of a mesoporous material is an attractive procedure since the enzyme is immobilized without any covalent bonding to a support which may be detrimental to the catalytic performance. The objective of this work is to compare the encapsulation and catalytic performance of lipase from Mucor miehei and trypsin from bovine pancreas, two hydrolases with rather dissimilar properties and structures. We also demonstrate the importance of the pore dimensions and the pH for proper function of the encapsulated enzyme. Mesoporous silica particles (SBA-15) with three different pore sizes (50 angstrom, 60 angstrom and 89 angstrom) were synthesized and hexagonal structures with narrow pore size distributions were confirmed with TEM, SAXS and N(2)-adsorption. Lipase and trypsin were encapsulated separately in the silica particles and the results indicate distinct differences between the two enzymes, both in loading capacity and catalytic activity. For trypsin the encapsulation rate and the loading capacity were large with a maximum reached at pH 7.6. The largest product yield was obtained with the particles with 60 angstrom pores, however, the yield was significantly lower than with free trypsin. For lipase optimal encapsulation rate and loading capacity were reached with the particles with 89 angstrom pores at pH 6.0 but were low compared to trypsin. However, the catalytic activity of the encapsulated lipase was more than twice as large as for free lipase, which can be explained by an interfacial activation of lipase at the silica surface

Immobilization of feruloyl esterases in mesoporous silica

Mesoporous silica materials have become popular as immobilization support for enzymes due to advantages such as high protein loading capacity and enhanced enzyme activity because of confinement into pores. Immobilization of enzymes is often required for sufficient enzyme stability and to enable recovery in industrially feasible and efficient processes. Feruloyl esterases is a class of enzymes used in biocatalysis for refinement of hydroxycinnamic acids. These compounds have shown to have antioxidant and antibacterial properties, though modification of solubility is necessary for the compounds to be of interest in different commercial products. Previous work has showed that mesoporous silica is a robust immobilization support for feruloyl esterases and that transesterification activity was favored over hydrolysis. Immobilization of feruloyl esterases (FoFAEC) in SBA-15 mesoporous silica showed to be highly affected by pH. Testing the immobilized enzymes for transesterification of methyl ferulate to butyl ferulate showed that the specific activity was affected by the pH at which the enzymes had been immobilized. Consequently there is a pH memory effect, which could be reverted by subsequent washing with a buffer of different pH. The current work involves testing a pH probe bound to the enzyme which will give information of the microenvironment pH close to the enzyme. Additionally, an in silico model of FoFAEC has been developed so that the dimensions of the enzyme can be related to the pore size. The model will also be used to simulate the enzyme structure at different pH, predict orientation and adsorption behavior. The aim is to understand how mesoporous materials can be used to alter the enzymatic activity upon immobilization and in the end develop improved feruloyl esterase biocatalysts that allow customization of the antioxidant properties of hydroxycinnamic acids

A method to measure pH inside mesoporous particles using protein-bound SNARF1 fluorescent probe

We use fluorescence spectroscopy to measure the pH sensed by proteins which are immobilized in mesoporous silica particles by covalently attaching the pH-probe SNARF1 to the proteins. In contrast to previous attempts where pH-probes were attached to the pore surface, the present approach allows the pH to be measured without altering the properties of the silica material. When the particles are suspended in aqueous solutions of various pH the emission spectra of the labeled proteins indicate an environment inside the pores which is closer to neutral compared to the bulk solution. In a 1-butanol/water mixture (92.5/7.5%) the emission spectra of the immobilized proteins report a pH-behavior typical of the aqueous suspensions, in contrast to the blue-shifted emission spectrum of the protein in the outside organic solvent. This observation shows that the immobilized proteins experience an aqueous pore environment even though the surrounding solution is poor in water. The spectra of SNARF1-labeled bovine serum albumin and feruloyl esterase generated similar results suggesting that the method can be applied to different types of proteins. Taken together the results show that spectroscopic probes carried by immobilized macromolecules can be used to characterize the environment inside mesoporous particles without perturbing the properties of the material

Understanding the pH-dependent immobilization efficacy of feruloyl esterase-C on mesoporous silica and its structure activity changes

The purpose of the present investigation was to study the pH dependence of both the immobilization process and the enzyme activity of a feruloyl esterase (FoFaeC from Fusarium oxysporum) immobilized in mesoporous silica. This was done by interpreting experimental results with theoretical molecular modeling of the enzyme structure. Modeling of the 3D structure of the enzyme together with calculations of the electrostatic surface potential showed that changes in the electrostatic potential of the protein surface were correlated with the pH dependence of the immobilization process. High immobilization yields were associated with an increase in pH. The transesterification activity of both immobilized and free enzyme was studied at different values of pH and the optimal pH of the immobilized enzyme was found to be one unit lower than that for the free enzyme. The surface charge distribution around the binding pocket was identified as being a crucial factor for the accessibility of the active site of the immobilized enzyme, indicating that the orientation of the enzyme inside the pores is pH dependent. Interestingly, it was observed that the immobilization pH affects the specific activity, irrespective of the changes in reaction pH. This was identified as a pH memory effect for the immobilized enzyme. On the other hand, a change in product selectivity of the immobilized enzyme was also observed when the transesterification reaction was run in MOPS buffer instead of citrate phosphate buffer. Molecular docking studies revealed that the MOPS buffer molecule can bind to the enzyme binding pocket, and can therefore be assumed to modulate the product selectivity of the immobilized enzyme toward transesterification

Real-world stress resilience is associated with the responsivity of the locus coeruleus

Individuals may show different responses to stressful events. Here, we investigate the neurobiological basis of stress resilience, by showing that neural responsitivity of the noradrenergic locus coeruleus (LC-NE) and associated pupil responses are related to the subsequent change in measures of anxiety and depression in response to prolonged real-life stress. We acquired fMRI and pupillometry data during an emotional-conflict task in medical residents before they underwent stressful emergency-room internships known to be a risk factor for anxiety and depression. The LC-NE conflict response and its functional coupling with the amygdala was associated with stress-related symptom changes in response to the internship. A similar relationship was found for pupil-dilation, a potential marker of LC-NE firing. Our results provide insights into the noradrenergic basis of conflict generation, adaptation and stress resilience