| 1. |
- Klionsky, Daniel J., et al.
(författare)
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Guidelines for the use and interpretation of assays for monitoring autophagy
- 2012
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Ingår i: Autophagy. - : Informa UK Limited. - 1554-8635 .- 1554-8627. ; 8:4, s. 445-544
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Forskningsöversikt (refereegranskat)abstract
- In 2008 we published the first set of guidelines for standardizing research in autophagy. Since then, research on this topic has continued to accelerate, and many new scientists have entered the field. Our knowledge base and relevant new technologies have also been expanding. Accordingly, it is important to update these guidelines for monitoring autophagy in different organisms. Various reviews have described the range of assays that have been used for this purpose. Nevertheless, there continues to be confusion regarding acceptable methods to measure autophagy, especially in multicellular eukaryotes. A key point that needs to be emphasized is that there is a difference between measurements that monitor the numbers or volume of autophagic elements (e.g., autophagosomes or autolysosomes) at any stage of the autophagic process vs. those that measure flux through the autophagy pathway (i.e., the complete process); thus, a block in macroautophagy that results in autophagosome accumulation needs to be differentiated from stimuli that result in increased autophagic activity, defined as increased autophagy induction coupled with increased delivery to, and degradation within, lysosomes (in most higher eukaryotes and some protists such as Dictyostelium) or the vacuole (in plants and fungi). In other words, it is especially important that investigators new to the field understand that the appearance of more autophagosomes does not necessarily equate with more autophagy. In fact, in many cases, autophagosomes accumulate because of a block in trafficking to lysosomes without a concomitant change in autophagosome biogenesis, whereas an increase in autolysosomes may reflect a reduction in degradative activity. Here, we present a set of guidelines for the selection and interpretation of methods for use by investigators who aim to examine macroautophagy and related processes, as well as for reviewers who need to provide realistic and reasonable critiques of papers that are focused on these processes. These guidelines are not meant to be a formulaic set of rules, because the appropriate assays depend in part on the question being asked and the system being used. In addition, we emphasize that no individual assay is guaranteed to be the most appropriate one in every situation, and we strongly recommend the use of multiple assays to monitor autophagy. In these guidelines, we consider these various methods of assessing autophagy and what information can, or cannot, be obtained from them. Finally, by discussing the merits and limits of particular autophagy assays, we hope to encourage technical innovation in the field.
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| 2. |
- Ballem, Mohamed A., et al.
(författare)
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Low Temperature Nanocasting of Ultrafine Hematite Nanoparticles using Mesoporous Silica Molds
- 2012
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Ingår i: Powder Technology. - : Elsevier. - 0032-5910 .- 1873-328X. ; 217, s. 269-273
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Tidskriftsartikel (refereegranskat)abstract
- Iron oxide (α-Fe2O3) nanoparticles with very small size, high crystallinity, and narrow size distribution were synthesized by infiltration of Fe(NO3)3.9H2O as an oxide precursor into mesoporous silica (SBA-15 and SBA-16) molds using a wetimpregnation technique. High resolution transmission electron microscopy shows that during the hydrothermal treatment of the precursor at 140 °C for 2 days, stable α-Fe2O3 nanoparticles inside the silica pores are formed. Subsequent leaching out of the silica template by NaOH resulted in well dispersed nanoparticles with an average diameter of ~ 4 nm.
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| 3. |
- Frodelius, Jenny, 1978-, et al.
(författare)
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Annealing of thermally sprayed Ti2AlC coatings
- 2011
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Ingår i: INTERNATIONAL JOURNAL OF APPLIED CERAMIC TECHNOLOGY. - : Blackwell. - 1546-542X. ; 8:1, s. 74-84
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Tidskriftsartikel (refereegranskat)abstract
- Phase transformations during annealing of coatings sprayed with the High Velocity Oxy-Fuel technique using Ti2AlC powder have been investigated by in-situ x-ray diffraction. The asdeposited coatings, consisting of Ti2AlC, Ti3AlC2, TiC, Ti-Al, and oxides, are stable up to 500 °C. Ti3AlC2 forms above 550 °C and Ti2AlC forms above 700 °C by intercalation of Al into TiCx. For temperatures between 900 and 1100 °C, Ti3AlC2 and Ti2AlC decompose by losing Al to the surrounding matrix resulting in TiCx, and Al2O3. The thermal expansion coefficient between ambient and 700°C is 11.9·10-6 K-1. The thermal diffusivity at room temperature is 1.9·10-6 m2/s.
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| 4. |
- Johansson, Emma M.
(författare)
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Controlling the Pore Size and Morphology of Mesoporous Silica
- 2010
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Mesoporous silica with a hexagonally ordered pore structure (SBA-15) has been synthesized. Through variations in the synthesis conditions several morphologies, such as fibers, sheets and separate rods, have been realized. Furthermore, additions of heptane and NH4F make it possible to synthesize SBA-15 with pores as large as 18 nm in the sheet morphology. Mechanisms for the formation of different morphologies have been suggested. In the case of fibers and sheets, the amount of heptane present during the synthesis determines the final morphology. For low concentrations, the heptane enters the micelles and increases the pore size while the particles (crystallites) attaches to each other end to end. When the heptane concentration increases, the heptane droplets increase in size, and above a critical droplet size the crystallites attach with one short end towards the droplet, forming the sheet morphology. The crystallites can also be separated. This is the case of the rod morphology. The separation is performed by shortening the stirring time and increasing the HCl concentration. The increased amount of HCl increases the hydration rate of the silica precursor, which can be used to control the thickness and length of the rods. Furthermore, the reaction time has been decreased from 20 h for all morphologies to less than 4 hours. The materials have been characterized with nitrogen sorption, electron microscopy and x-ray diffraction. Also, thermogravimetric analysis and fourier transformed infrared spectroscopy have been used for studying the removal of surfactants.
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| 5. |
- Spencer, C B, et al.
(författare)
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Phase Evaluation in Al(2)O(3) Fiber-Reinforced Ti(2)AlC During Sintering in the 1300 degrees C-1500 degrees C Temperature Range
- 2011
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Ingår i: Journal of The American Ceramic Society. - : Wiley-Blackwell. - 0002-7820 .- 1551-2916. ; 94:10, s. 3327-3334
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Tidskriftsartikel (refereegranskat)abstract
- In this article, the reactivity of Ti(2)AlC powders, with 3 and 10 mu m alumina, Al(2)O(3), fibers during pressure-assisted sintering is explored. Samples were fabricated by hot-isostatic-pressing (HIPed) or hot-pressing (HPed), and characterized by X-ray diffraction, differential thermal analysis, and electron microscopy-both scanning and transmission-equipped with energy dispersive X-ray spectroscopes. Samples prepared at 1300 degrees C were fully dense, with no apparent reaction between fiber and matrix. In samples HPed to 1500 degrees C, even pure Ti(2)AlC powders dissociated to Ti(3)AlC(2) according to: 2 Ti(2)AlC = Ti(3)AlC(2) + TiAl(x) (l) + (1-x) Al (l/v), with x andlt; 1. More severe Al loss results in the formation of TiC(y). The presence of the Al(2)O(3) fibers delayed densification enough to allow most of the Al and some of the Ti to escape into the vacuum of the hot press or react with the encapsulating glass during HIPing a resulting in a more intensive dissociation of the Ti(2)AlC. Although, in principle Ti(2)AlC can be reinforced with Al(2)O(3) fibers, the processing/use temperature will have to be kept below 1500 degrees C, as, at that temperature the fibers, used here, sinter together.
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| 6. |
- Tamayo-Ariztondo, J., et al.
(författare)
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Effect of heat treatment of carbon nanofibres on electroless copper deposition
- 2010
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Ingår i: Composites Science And Technology. - : Elsevier BV. - 0266-3538 .- 1879-1050. ; 70:16, s. 2269-2275
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Tidskriftsartikel (refereegranskat)abstract
- Cu is a well known heat sink material due to its high thermal conductivity. However, its coefficient of thermal expansion (CTE) is high. One of the most promising solutions for reducing it is to reinforce copper with carbon nanofibres (CNF) because of their low CTE. To exploit the properties of the CNFs a good dispersion of the reinforcement within the matrix must be achieved. One of the processing methods used to obtain a homogeneous CNF distribution is coating the CNF with Cu using electrochemical deposition. In this paper, the effect of the carbon structure on electroless deposition technique is studied. Different CNF have been compared: herringbone (HB), platelet (PL) and longitudinally aligned (previously heat treated) (LAHT). Herringbone and Platelet CNF were heat treated at 2750 °C for 30′ which resulted in a structure resembling graphite with loops at the fibre surface. These loops are responsible for an enhancement of the copper coating. It is shown that the Cu coverage in electroless deposition is high for the graphene plane and poor at the edges of the plane.
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| 7. |
- Ullbrand, Jennifer, et al.
(författare)
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Thermomechanical properties of copper-carbon nanofibre composites prepared by spark plasma sintering and hot pressing
- 2010
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Ingår i: Composites Science And Technology. - : Elsevier BV. - 0266-3538 .- 1879-1050. ; 70:16, s. 2263-2268
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Tidskriftsartikel (refereegranskat)abstract
- Several types of carbon nanofibres (CNF) were coated with a uniform and dense copper layer by electroless copper deposition. The coated fibres were then sintered by two different methods, spark plasma sintering (SPS) and hot pressing (HP). The Cu coating thickness was varied so that different volume fraction of fibres was achieved in the produced composites. In some cases, the CNF were pre-coated with Cr for the improvement the Cu adhesion on CNF. The results show that the dispersion of the CNF into the Cu matrix is independent of the sintering method used. On the contrary, the dispersion is directly related to the efficiency of the Cu coating, which is tightly connected to the CNF type. Overall, strong variations of the thermal conductivity (TC) of the composites were observed (20-200 W/mK) as a function of CNF type, CNF volume fraction and Cr content, while the coefficient of thermal expansion (CTE) in all cases was found to be considerably lower than Cu (9.9-11.3 ppm/K). The results show a good potential for SPS to be used to process this type of materials, since the SPS samples show better properties than HP samples even though they have a higher porosity, in applications where moderate TC and low CTE are required.
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| 8. |
- Ballem, Mohamed A., et al.
(författare)
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Influence of synthesis temperature on morphology of SBA-16 mesoporous materials with a three-dimensional pore system
- 2010
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Ingår i: Microporous and Mesoporous Materials. - : Elsevier BV. - 1387-1811 .- 1873-3093. ; 129, s. 106-111
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Tidskriftsartikel (refereegranskat)abstract
- Spherical particles of mesoporous silica SBA-16 with cubic Im3m structure were synthesized at low pH using Pluronic F127 as template and TEOS as silica source. The diameter of the spherical particles can be controlled in the range of 0.5–8 μm by varying synthesis temperature from 1 °C up to 40 °C. A sharp transition from large particle sizes at approximately 20 °C to smaller ones is observed when the temperature is increased. It is suggested that this morphology transition is due to a change in hydrolysis and condensation rate of the silica source and as a result the assembly of F127 micelles will differ. The SBA-16 samples were characterized using powder X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and nitrogen adsorption techniques.
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| 9. |
- Ballem, Mohamed A.
(författare)
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Synthesis of Mesoporous Silica and their Use as Templates for Metal and Metal Oxide Nanoparticles
- 2011
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- This thesis covers the synthesis and characterization of two types of mesoporous silica, SBA-15 silica with two-dimensional hexagonal arrangement, and SBA-16 silica with three-dimensional cubic arrangement. The obtained mesoporous materials were then used as hard templates for synthesizing of different types of nanostructures. In the first part, the effects of some synthesis parameters on the morphology and texture properties of the mesoporous silica have been studied. By varying the synthesis temperature solid spheres of SBA-16 with different sizes were synthesized and by additions of heptane as a swelling agent, SBA-16 in a hollow-sphere morphology with a large pore size was obtained. In the case of SBA-15, dispersed rods were synthesized in the presence of heptane and NH4F in a low-temperature synthesis. The length of the rods was varied by changing the concentration of HCl, and the pore size was tuned by changing the hydrothermal treatment time and temperature. Furthermore, the reaction time was decreased with a well-retained pore size and morphology. This work has resulted in SBA-15 rods with large pore sizes for this morphology. In the second part, SBA-15 and SBA-16 silica were used to synthesize different nanostructured materials such as metal and metal oxide nanoparticles. In fact, most of the work in this part is focused on the use of mesoporous silica as hard templates for synthesis of different types of nanoparticles. The synthesis of these nanoparticles was carried out by infiltration of a suitable precursor in the pores of the silica template. The mesoporous frameworks act as molds controlling the size and the final shape of the formed nanostructures. Subsequent dissolution of the silica templates by NaOH resulted in e.g., monodispersed zirconia, hematite, and cobalt nanoparticles with narrow size distributions. Functionalization of the SBA-15 surfaces was carried out in the synthesis of cobalt nanoparticles. This functionalization plays a crucial role on the infiltration and reaction of the reagents in the pores of the silica. By functionalization of the external surface, a highly hydrophobic surface was achieved, which proved to be sufficient to avoid formation of large cobalt particles outside the silica channels, while the internal functionalization enhances the attraction of cobalt ions to the silica pores, and as a result the nanoparticles grew inside these pores.
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| 10. |
- Balmativola, D., et al.
(författare)
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Pathological non-response to chemotherapy in a neoadjuvant setting of breast cancer: an inter-institutional study
- 2014
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Ingår i: Breast Cancer Research and Treatment. - : Springer Science and Business Media LLC. - 1573-7217 .- 0167-6806. ; 148:3, s. 511-523
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Tidskriftsartikel (refereegranskat)abstract
- To identify markers of non-response to neoadjuvant chemotherapy (NAC) that could be used in the adjuvant setting. Sixteen pathologists of the European Working Group for Breast Screening Pathology reviewed the core biopsies of breast cancers treated with NAC and recorded the clinico-pathological findings (histological type and grade; estrogen, progesterone receptors, and HER2 status; Ki67; mitotic count; tumor-infiltrating lymphocytes; necrosis) and data regarding the pathological response in corresponding surgical resection specimens. Analyses were carried out in a cohort of 490 cases by comparing the groups of patients showing pathological complete response (pCR) and partial response (pPR) with the group of non-responders (pathological non-response: pNR). Among other parameters, the lobular histotype and the absence of inflammation were significantly more common in pNR (p < 0.001). By ROC curve analyses, cut-off values of 9 mitosis/2 mm(2) and 18 % of Ki67-positive cells best discriminated the pNR and pCR + pPR categories (p = 0.018 and < 0.001, respectively). By multivariable analysis, only the cut-off value of 9 mitosis discriminated the different response categories (p = 0.036) in the entire cohort. In the Luminal B/HER2- subgroup, a mitotic count < 9, although not statistically significant, showed an OR of 2.7 of pNR. A lobular histotype and the absence of inflammation were independent predictors of pNR (p = 0.024 and < 0.001, respectively). Classical morphological parameters, such as lobular histotype and inflammation, confirmed their predictive value in response to NAC, particularly in the Luminal B/HER2- subgroup, which is a challenging breast cancer subtype from a therapeutic point of view. Mitotic count could represent an additional marker but has a poor positive predictive value.
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