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Query: "author" (Franc Bo%C5%BEi%C4%8Dek) .

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1.
Effect of Ti and S content on the properties and machinability of low-carbon ferritic–pearlitic steel
Boštjan Arh, Franc Tehovnik, Franci Vode, Bojan Podgornik, 2024, original scientific article

Abstract: This research was focused on the effect of Ti and S content on the formation of non-metallic inclusions and their influence on the mechanical properties and machinability of low-carbon ferritic– pearlitic steels. An analysis and classification of the non-metallic inclusions were carried out. The tensile strength and impact toughness were determined from samples taken in the rolling direction. Machinability investigations were carried out on a CNC turning machine and by analyzing the surface roughness. TiO-TiN inclusions are present in steels with an increased Ti content. In these steels, the hardness, tensile strength, and cutting forces increase with a higher proportion of Ti. In the second group of steels with increased contents of S, Al, and Ca, MnS and CaO-Al2O3-MnS non-metallic inclusions are formed. As the S content increases, the tensile strength and cutting forces decrease, while the impact toughness increases. In steels with added Ti, the This research was focused on the effect of Ti and S content on the formation of non-metallic inclusions and their influence on the mechanical properties and machinability of low-carbon ferritic– pearlitic steels. An analysis and classification of the non-metallic inclusions were carried out. The tensile strength and impact toughness were determined from samples taken in the rolling direction. Machinability investigations were carried out on a CNC turning machine and by analyzing the surface roughness. TiO-TiN inclusions are present in steels with an increased Ti content. In these steels, the hardness, tensile strength, and cutting forces increase with a higher proportion of Ti. In the second group of steels with increased contents of S, Al, and Ca, MnS and CaO-Al2O3-MnS non-metallic inclusions are formed. As the S content increases, the tensile strength and cutting forces decrease, while the impact toughness increases. In steels with added Ti, the machining is more difficult, but a finer surface is achieved after turning, while a higher S content results in an increased fraction of softer sulfide inclusions, which reduce the cutting forces but also result in a reduced surface quality. turning, while a higher S content results in an increased fraction of softer sulfide inclusions, which reduce the cutting forces but also result in a reduced surface quality.
Keywords: non-metallic inclusions, mechanical properties, machinability, surface roughness
Published in DiRROS: 03.09.2024; Views: 123; Downloads: 366
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2.
Structural basis for the multitasking nature of the potato virus Y coat protein
Andreja Kežar, Luka Kavčič, Martin Pólak, Jiři Nováček, Ion Gutiérrez-Aguirre, Magda Tušek-Žnidarič, Anna Coll Rius, Katja Stare, Kristina Gruden, Maja Ravnikar, David Pahovnik, Ema Žagar, Franci Merzel, Gregor Anderluh, Marjetka Podobnik, 2019, original scientific article

Abstract: Potato virus Y (PVY) is among the most economically important plant pathogens. Using cryoelectron microscopy, we determined the near-atomic structure of PVY’s flexuous virions, revealing a previously unknown lumenal interplay between extended carboxyl-terminal regions of the coat protein units and viral RNA. RNA–coat protein interactions are crucial for the helical configuration and stability of the virion, as revealed by the unique near-atomic structure of RNA-free virus-like particles. The structures offer the first evidence for plasticity of the coat protein’s amino- and carboxyl-terminal regions. Together with mutational analysis and in planta experiments, we show their crucial role in PVY infectivity and explain the ability of the coat protein to perform multiple biological tasks. Moreover, the high modularity of PVY virus-like particles suggests their potential as a new molecular scaffold for nanobiotechnological applications.
Keywords: plant pathogens, potato virus Y, viral RNA
Published in DiRROS: 23.07.2024; Views: 214; Downloads: 183
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3.
Embedded complex curves in the affine plane
Antonio Alarcón, Franc Forstnerič, 2024, original scientific article

Abstract: This paper brings several contributions to the classical Forster-Bell-Narasimhan conjecture and the Yang problem concerning the existence of proper and almost proper (hence complete) injective holomorphic immersions of open Riemann surfaces in the affine plane ${\mathbb C}^2$ satisfying interpolation and hitting conditions. We also show that in every compact Riemann surface there is a Cantor set whose complement admits a proper holomorphic embedding in ${\mathbb C}^2$. The focal point is a lemma saying the following. Given a compact bordered Riemann surface, $M$, a closed discrete subset $E$ of its interior ${\mathring M}=M\setminus bM$, a compact subset $K\subset {\mathring M}\setminus E$ without holes in $\mathring M$, and a ${\cal C}^1$ embedding $f: M\hookrightarrow \mathbb C^2$ which is holomorphic in $\mathring M$, we can approximate $f$ uniformly on $K$ by a holomorphic embedding $F: bM\hookrightarrow {\mathbb C}^2$ which maps $E\cup bM$ out of a given ball and satisfies some interpolation conditions.
Keywords: Riemann surfaces, complex curves, complete holomorphic embedding
Published in DiRROS: 15.07.2024; Views: 216; Downloads: 122
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4.
Ohranjanje gozdnih genskih virov s semenskim praktikumom
Hojka Kraigher, 2024, reviewed university, higher education or higher vocational education textbook

Keywords: gozdni reprodukcijski material, zakonodaja, certifikacija, gozdni reprodukcijski material, ohranjanje gozdnih genskih virov
Published in DiRROS: 08.07.2024; Views: 280; Downloads: 196
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Induction chemotherapy, chemoradiotherapy and consolidation chemotherapy in preoperative treatment of rectal cancer : long-term results of phase II OIGIT-01 Trial
Danijela Golo, Jasna But-Hadžić, Franc Anderluh, Erik Brecelj, Ibrahim Edhemović, Ana Jeromen, Mirko Omejc, Irena Oblak, Ajra Šečerov Ermenc, Vaneja Velenik, 2018, original scientific article

Abstract: The purpose of the study was to improve treatment efficacy for locally advanced rectal cancer (LARC) by shifting half of adjuvant chemotherapy preoperatively to one induction and two consolidation cycles. Patients and methods Between October 2011 and April 2013, 66 patients with LARC were treated with one induction chemotherapy cycle followed by chemoradiotherapy (CRT), two consolidation cycles, surgery and three adjuvant capecitabine cycles. Radiation doses were 50.4 Gy for T2-3 and 54 Gy for T4 tumours in 1.8 Gy daily fraction. The doses of concomitant and neo/adjuvant capecitabine were 825 mg/m2/12h and 1250mg/m2/12h, respectively. The primary endpoint was pathologic complete response (pCR). Results Forty-three (65.1%) patients were treated according to protocol. The compliance rates for induction, consolidation, and adjuvant chemotherapy were 98.5%, 93.8% and 87.3%, respectively. CRT was completed by 65/66 patients, with G % 3 non-hematologic toxicity at 13.6%. The rate of pCR (17.5%) was not increased, but N and the total-down staging rates were 77.7% and 79.3%, respectively. In a median follow-up of 55 months, we recorded one local relapse (LR) (1.6%). The 5-year disease-free survival (DFS) and overall survival (OS) rates were 64.0% (95% CI 63.89%64.11) and 69.5% (95% CI 69.39%69.61), respectively. Conclusions In LARC preoperative treatment intensification with capecitabine before and after radiotherapy is well tolerated, with a high compliance rate and acceptable toxicity. Though it does not improve the local effect, it achieves a high LR rate, DFS, and OS.
Keywords: rectal cancer, neoadjuvant chemotherapy, preoperative chemoradiotherapy
Published in DiRROS: 11.06.2024; Views: 235; Downloads: 122
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8.
Proper holomorphic embeddings with small limit sets
Franc Forstnerič, 2024, original scientific article

Abstract: Let $X$ be a Stein manifold of dimension $n\ge 1$. Given a continuous positive increasing function $h$ on ${\mathbb R}_+ = [0,\infty)$ with $\lim_{t\to\infty} h(t)=\infty$, we construct a proper holomorphic embedding $f=(z,w):X \hookrightarrow {\mathbb C}^{n+1}\times {\mathbb C}^n$ satisfying $|w(x)|Keywords: Stein manifold, proper holomorphic embedding
Published in DiRROS: 13.05.2024; Views: 332; Downloads: 254
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9.
The impact of anaemia on treatment outcome in patients with squamous cell carcinoma of anal canal and anal margin
Irena Oblak, Monika Češnjevar, Mitja Anžič, Jasna But-Hadžić, Ajra Šečerov Ermenc, Franc Anderluh, Vaneja Velenik, Ana Jeromen, Peter Korošec, 2016, original scientific article

Abstract: Radiochemotherapy is the main treatment for patients with squamous cell carcinoma of the anal canal. Anaemia is reported to have adverse effect on survival in cancer patients. The aim of the study was to evaluate the influence of anaemia on radiochemotherapy treatment outcome in patients with squamous cell carcinoma of the anal canal. Patients and methods. One hundred consecutive patients with histologically confirmed squamous cell carcinoma of the anal canal were treated radically with 3-dimensional conformal or intensity-modulated radiation therapy followed by brachytherapy or external beam radiotherapy boost and with concurrent mitomycin C and 5-fluorouracil. The influence on survival of pre-treatment, mean on-treatment and end-of-treatment haemoglobin (Hb) concentrations was studied. Results. The 5-year locoregional control, disease free survival, disease specific survival and overall survival rates for all patients were 72%, 71%, 77% and 62%, respectively. In univariate analysis, patients with pre-treatment and end-oftreatment Hb > 120 g/L survived statistically significantly better compared to patients with Hb % 120 g/L. Patients with mean on-treatment Hb > 120 g/L only had statistically significant better locoregional control and overall survival than patients with Hb % 120 g/L. In multivariate analysis, independent prognostic factors were pre-treatment Hb (> 120 g/L vs. % 120 g/L) for overall survival (hazard ratio [HR] = 0.419, 95% confidence interval [CI] = 0.190%0.927, p = 0.032) and stage (I & II vs. III) for disease specific (HR = 3.523, 95% CI = 1.375%9.026, p = 0.009) and overall survival (HR = 2.230, 95% CI = 1.167%4.264, p = 0.015). Conclusions. The pre-treatment, mean on-treatment and end-of-treatment Hb concentration > 120 g/L carried better prognosis for patients for with squamous cell carcinoma of the anal canal treated with radiochemotherapy. The pre-treatment Hb > 120 g/L was an independent prognostic factor for overall survival of patients with anal canal cancer.
Keywords: anaemia, anal canal squamous cell carcinoma, radiochemotherapy
Published in DiRROS: 30.04.2024; Views: 380; Downloads: 211
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10.
Schwarz-Pick lemma for harmonic maps which are conformal at a point
Franc Forstnerič, David Kalaj, 2024, original scientific article

Abstract: We obtain a sharp estimate on the norm of the differential of a harmonic map from the unit disc ${\mathbb D}$ in ${\mathbb C}$ into the unit ball ${\mathbb B}^n$ in ${\mathbb R}^n$, $n\ge 2$, at any point where the map is conformal. In dimension $n=2$, this generalizes the classical Schwarz-Pick lemma, and for $n\ge 3$ it gives the optimal Schwarz-Pick lemma for conformal minimal discs ${\mathbb D}\to {\mathbb B}^n$. This implies that conformal harmonic immersions $M \to {\mathbb B}^n$ from any hyperbolic conformal surface are distance-decreasing in the Poincaré metric on $M$ and the Cayley-Klein metric on the ball ${\mathbb B}^n$, and the extremal maps are precisely the conformal embeddings of the disc ${\mathbb D}$ onto affine discs in ${\mathbb B}^n$. Motivated by these results, we introduce an intrinsic pseudometric on any Riemannian manifold of dimension at least three by using conformal minimal discs, and we lay foundations of the corresponding hyperbolicity theory.
Keywords: harmonic maps, minimal surfaces, Schwarz–Pick lemma, Cayley–Klein metric
Published in DiRROS: 25.04.2024; Views: 387; Downloads: 204
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