| 75251. |
- Kovacic, Suzana, et al.
(author)
-
Construction and Characterization of Kilobasepair Densely Labeled Peptide-DNA
- 2014
-
In: Biomacromolecules. - : American Chemical Society (ACS). - 1526-4602 .- 1525-7797. ; 15:11, s. 4065-4072
-
Journal article (peer-reviewed)abstract
- Directed assembly of biocompatible materials benefits from modular building blocks in which structural organization is independent of introduced functional modifications. For soft materials, such modifications have been limited. Here, long DNA is successfully functionalized with dense decoration by peptides. Following introduction of alkyne-modified nucleotides into kilobasepair DNA, measurements of persistence length show that DNA mechanics are unaltered by the dense incorporation of alkynes (similar to 1 alkyne/2 bp) and after click-chemistry attachment of a tunable density of peptides. Proteolytic cleavage of densely tethered peptides (similar to 1 peptide/3 bp) demonstrates addressability of the functional groups, showing that this accessible approach to creating hybrid structures can maintain orthogonality between backbone mechanics and overlaid function. The synthesis and characterization of these hybrid constructs establishes the groundwork for their implementation in future applications, such as building blocks in modular approaches to a range of problems in synthetic biology.
|
|
| 75252. |
- Kovacic, Suzana, et al.
(author)
-
Design and Construction of a One- Dimensional DNA Track for an Artificial Molecular Motor
- 2012
-
In: Journal of Nanomaterials. - : Hindawi Limited. - 1687-4129 .- 1687-4110.
-
Journal article (peer-reviewed)abstract
- DNA is a versatile heteropolymer that shows great potential as a building block for a diverse array of nanostructures. We present here a solution to the problem of designing and synthesizing a DNA-based nanostructure that will serve as the track along which an artificial molecular motor processes. This one-dimensional DNA track exhibits periodically repeating elements that provide specific binding sites for the molecular motor. Besides these binding elements, additional sequences are necessary to label specific regions within the DNA track and to facilitate track construction. Designing an ideal DNA track sequence presents a particular challenge because of the many variable elements that greatly expand the number of potential sequences from which the ideal sequence must be chosen. In order to find a suitable DNA sequence, we have adapted a genetic algorithm which is well suited for a large but sparse search space. This algorithm readily identifies long DNA sequences that include all the necessary elements to both facilitate DNA track construction and to present appropriate binding sites for the molecular motor. We have successfully experimentally incorporated the sequence identified by the algorithm into a long DNA track meeting the criteria for observation of the molecular motor's activity.
|
|
| 75253. |
|
|
| 75254. |
- Kovacic, Suzana, et al.
(author)
-
Design and Construction of the Lawnmower, An Artificial Burnt-Bridges Motor
- 2015
-
In: IEEE Transactions on Nanobioscience. - 1558-2639. ; 14:3, s. 305-312
-
Journal article (peer-reviewed)abstract
- Molecular motors of the cell are protein-based, nanoscale machines, which use a variety of strategies to transduce chemical energy into mechanical work in the presence of a large thermal background. The design and construction of artificial molecular motors is one approach to better understand their basic physical principles. Here, we propose the concept of a protein-based, burnt-bridges ratchet, inspired by biological examples. Our concept, the lawnmower, utilizes protease blades to cleave peptide substrates, and uses the asymmetric substrate-product interface arising from productive cleavage to bias subsequent diffusion on the track (lawn). Following experimental screening to select a protease to act as the motor's blades, we chemically couple trypsin to quantum dots and demonstrate activity of the resulting lawnmower construct in solution. Accompanying Brownian dynamics simulations illustrate the importance for processivity of correct protease density on the quantum dot and spacing of substrates on the track. These results lay the groundwork for future tests of the protein-based lawnmower's motor performance characteristics.
|
|
| 75255. |
- Kovacs, Andras, et al.
(author)
-
Effect of post-growth annealing on secondary phase formation in low-temperature-grown Mndoped GaAs
- 2013
-
In: Journal of Physics D: Applied Physics. - : IOP Publishing. - 1361-6463 .- 0022-3727. ; 46:14, s. 7-145309
-
Journal article (peer-reviewed)abstract
- The microstructures of annealed GaAs layers containing 0.1%, 0.5% and 2% Mn are studied using aberration-corrected transmission electron microscopy (TEM). The layers were grown by molecular beam epitaxy at 270 ◦C. After heat treatment at 400, 560 and 630 ◦C, they are found to contain precipitate complexes of cubic or hexagonal (Mn, Ga) As, orthorhombic or rhombohedral As and voids. Information about the crystallographic structures and compositions of the phases is obtained using high-resolution TEM, scanning TEM and energy-dispersive x-ray spectroscopy. A phase diagram for secondary phase formation in annealed GaMnAs layers doped with low Mn concentrations is proposed.
|
|
| 75256. |
- Kovács, Anikó, 1961, et al.
(author)
-
Effect of Radiotherapy After Breast-Conserving Surgery Depending on the Presence of Tumor-Infiltrating Lymphocytes : A Long-Term Follow-Up of the SweBCG91RT Randomized Trial
- 2019
-
In: Journal of Clinical Oncology. - 0732-183X. ; 37:14, s. 1179-87
-
Journal article (peer-reviewed)abstract
- PURPOSE: The effects of radiotherapy (RT) on the basis of the presence of stromal tumor infiltrating lymphocytes (TILs) have not been studied. The purpose of this study was to analyze the association of TILs with the effect of postoperative RT on ipsilateral breast tumor recurrence (IBTR) in a large randomized trial. METHODS: In the SweBCT91RT (Swedish Breast Cancer Group 91 Radiotherapy) trial, 1,178 patients with breast cancer stage I and II were randomly assigned to breast-conserving surgery plus postoperative RT or breast-conserving surgery only and followed for a median of 15.2 years. Tumor blocks were retrieved from 1,003 patients. Stromal TILs were assessed on whole-section hematoxylin-eosin-stained slides using a dichotomized cutoff of 10%. Subtypes were scored using immunohistochemistry on tissue microarray. In total, 936 patients were evaluated. RESULTS: Altogether, 670 (71%) of patients had TILs less than 10%. In a multivariable regression analysis with IBTR as dependent variable and RT, TILs, subtype, age, and grade as independent variables, RT (hazard ratio [HR], 0.42; 95% CI, 0.29 to 0.61; P < .001), high TILs (HR, 0.61; 95% CI, 0.39 to 0.96, P = .033) grade (3 v 1; HR, 2.17; 95% CI, 1.08 to 4.34; P = .029), and age (≥ 50 v < 50 years; HR, 0.55; 95% CI, 0.38 to 0.80; P = .002) were predictive of IBTR. RT was significantly beneficial in the low TILs group (HR, 0.37; 95% CI, 0.24 to 0.58; P < .001) but not in the high TILs group (HR, 0.58; 95% CI, 0.28 to 1.19; P = .138). The test for interaction between RT and TILs was not statistically significant (P = .317). CONCLUSION: This study shows that high values of TILs in the primary tumor independently seem to reduce the risk for an IBTR. Our findings further suggest that patients with breast cancer with low TILs may derive a larger benefit from RT regarding the risk of IBTR.
|
|
| 75257. |
- Kovacs, A., et al.
(author)
-
Voids and Mn-rich inclusions in a (Ga,Mn)As ferromagnetic semiconductor investigated by transmission electron microscopy
- 2011
-
In: Applied Physics Reviews. - : AIP Publishing. - 1931-9401. ; 109:8, s. 1-083546
-
Journal article (peer-reviewed)abstract
- Voids adjacent to cubic (ZnS-type) and hexagonal (NiAs-type) Mn-rich nanocrystals are characterized using aberration-corrected transmission electron microscopy in an annealed Ga(0.995)Mn(0.005)As magnetic semiconductor specimen grown by molecular beam epitaxy. Nanobeam electron diffraction measurements suggest that the nanocrystals exhibit deviations in lattice parameter as compared to bulk MnAs. After annealing at 903 K, the magnetic transition temperature of the specimen is likely to be dominated by the presence of cubic ferromagnetic nanocrystals. In situ annealing inside the electron microscope is used to study the nucleation, coalescence, and grain growth of individual nanocrystals.
|
|
| 75258. |
- Kovács, Gyöngyi, et al.
(author)
-
Gender mainstreaming in humanitarian purchasing
- 2011
-
In: Gender, peace and development.
-
Conference paper (peer-reviewed)abstract
- Abstract in UndeterminedIn the humanitarian context, gender mediates access to aid. The gender of the beneficiary is not only intrinsically linked with her/his disaster vulnerability (Enarson, 2002), but also to their ability to physically access aid distribution points (Lutz and Gady, 2004) and even to be considered a beneficiary in the first place. There is, however, yet another factor mitigating an individual’s access to aid: namely the humanitarian organization and its workers (Kovács and Tatham, 2009).Particularly in the case of purchasing within humanitarian organizations, it is both the mainstreaming of gender among purchasers and as well as the use of the purchasing function itself to empower women that deserve attention. In relation to the latter, humanitarian organizations have frequently adopted a strategy aimed at increasing the income, skills and influence of women in local communities by purchasing from them (UNOPS, 2010). In case of former, the gender of the purchaser has been linked to the quality of decision-making in, for example, deciding what products to buy and distribute to beneficiaries (Min et al., 1995). In particular, the gender of the decision maker affects their awareness of gender specific needs, and there is ample evidence of the wrong items being bought and of the needs of female beneficiaries not being considered sufficiently well in purchasing decisions. Examples of such failings include the provision of tents for refugee/IDP camps made of transparent materials that made it possible to detect females who were alone and, thus, exposed them to sexual violence; or the absence of hygiene items for females. Purchasing decisions are, thus, linked to the safety and hygiene, health and wellbeing the beneficiaries.Gender is, therefore, an important aspect that purchasers in the humanitarian context need to consider - and yet it is an area of current practice that has frequently been overlooked. However, this is less surprising when one considers the gender ratios of purchasing decision-makers which, in the humanitarian context, can range from 70:30 up to 90:10 male to female. Thus, although gender mainstreaming is undoubtedly on the agenda of many humanitarian organizations, there is clear evidence that this strategic aim yet to be implemented in the area of purchasing. The aim of this research is, therefore, to improve the situation of beneficiaries through diverse and more gender-aware purchasing decisions.
|
|
| 75259. |
- Kovacs, Gabor, et al.
(author)
-
Graphite electrodes modified with Neurospora crassa cellobiose dehydrogenase: Comparative electrochemical characterization under direct and mediated electron transfer
- 2012
-
In: Bioelectrochemistry. - : Elsevier BV. - 1878-562X .- 1567-5394. ; 88, s. 84-91
-
Journal article (peer-reviewed)abstract
- The electrochemical characterization of a class II cellobiose dehydrogenase (CDH), from the ascomycete fungus Neurospora crassa. adsorbed on graphite (G), was performed in regard to direct (DET) and mediated electron transfer (MET). The effects of the applied potential, mediator (1,4 benzoquinone) concentration and flow carrier pH on the amperometric response of the G/CDH modified electrodes were investigated under flow conditions. From the calibration curves, recorded at two pH values (5.2 and 7.0) for nine different sugars, the kinetic and the analytical parameters were evaluated under DET and MET operation modes. These results together with those obtained from long term operational stability measurements showed that: (i) for all nine investigated sugars the sensitivity was higher for MET than for DET and for pH 5.2 compared to pH 7.0; (ii) irrespective of DET or MET operation mode, the sensitivity of the new enzyme towards the investigated sugars decreased in the following sequence: cellobiose > lactose > (cellotriose approximate to cellopentaose) > > (maltotriose approximate to maltotetraose approximate to maltopentaose) > (maltose approximate to glucose); (iii) for all tested substrates, the apparent CDH affinity was roughly higher in DET than in MET operation mode. (C) 2012 Elsevier B.V. All rights reserved.
|
|
| 75260. |
- Kovacs, Krisztina, et al.
(author)
-
Comparative enzymatic hydrolysis of pretreated spruce by supernatants, whole fermentation broths and washed mycelia of Trichoderma reesei and Trichoderma atroviride.
- 2009
-
In: Bioresource Technology. - : Elsevier BV. - 1873-2976 .- 0960-8524. ; 100:3, s. 1350-1357
-
Journal article (peer-reviewed)abstract
- Cellulase and beta-glucosidase production on steam pretreated spruce (SPS) with Trichoderma reesei Rut C30, Trichoderma atroviride TUB F-1505 and TUB F-1663 was investigated. The enzymes were compared in term of activity, temperature optima and hydrolytic capacity. The T. atroviride cellulases proved to have lower temperature optima for filter paper activity (FPA) assay (50 degrees C) and for hydrolysis of SPS (40 degrees C) than the Rut C30 enzymes (60 degrees C for FPA and 50 degrees C for hydrolysis). Due to high levels of extracellular beta-glucosidases, the T. atroviride enzyme supernatants hydrolyzed the washed SPS to glucose more efficiently than the enzymes produced by T. reesei. On the other hand, when the whole fermentation broths were used instead of the supernatants, thus the mycelium bound enzymes were also present, the hydrolytic capacity of T. reesei Rut C30 was enhanced by approximately 200%, while an improvement of only 15% was observed in case of the T. atroviride isolates.
|
|
