Combinatorics, Probability & Computing最新文献

{"title":"Получение металлического горючего AlB2 методом самораспространяющегося высокотемпературного синтеза и высокоэнергетические составы на его основе","authors":"С. Х. Акназаров, А. Б. Сейсенова, У.Д. Диканбай, А.Ж. Мутушев, Хуан Мария Гонсалес-Лил","doi":"10.18321/CPC402","DOIUrl":"https://doi.org/10.18321/CPC402","url":null,"abstract":"В работе исследована возможность получения диборида алюминия методом самораспространяющегося высокотемпературного синтеза (СВС), рассчитаны термодинамические параметры синтеза, выбран компонентный состав шихты. Экспериментально подобран количественный состав шихты для получения в процессе синтеза диборида алюминия, отвечающего предъявляемыми к нему требованиями, с максимальным выходом.","PeriodicalId":10513,"journal":{"name":"Combinatorics, Probability & Computing","volume":"18 1","pages":"200-210"},"PeriodicalIF":0.9,"publicationDate":"2020-12-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43861441","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Clustered colouring of graph classes with bounded treedepth or pathwidth","authors":"S. Norin, A. Scott, D. Wood","doi":"10.1017/S0963548322000165","DOIUrl":"https://doi.org/10.1017/S0963548322000165","url":null,"abstract":"The \"clustered chromatic number\" of a class of graphs is the minimum integer $k$ such that for some integer $c$ every graph in the class is $k$-colourable with monochromatic components of size at most $c$. We determine the clustered chromatic number of any minor-closed class with bounded treedepth, and prove a best possible upper bound on the clustered chromatic number of any minor-closed class with bounded pathwidth. As a consequence, we determine the fractional clustered chromatic number of every minor-closed class.","PeriodicalId":10513,"journal":{"name":"Combinatorics, Probability & Computing","volume":"11 1","pages":"122-133"},"PeriodicalIF":0.9,"publicationDate":"2020-12-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"73419589","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"On tripartite common graphs","authors":"Andrzej Grzesik, Joonkyung Lee, Bernard Lidick'y, Jan Volec","doi":"10.1017/s0963548322000074","DOIUrl":"https://doi.org/10.1017/s0963548322000074","url":null,"abstract":"\u0000 A graph \u0000 \u0000 \u0000 \u0000$H$\u0000\u0000 \u0000 is common if the number of monochromatic copies of \u0000 \u0000 \u0000 \u0000$H$\u0000\u0000 \u0000 in a 2-edge-colouring of the complete graph \u0000 \u0000 \u0000 \u0000$K_n$\u0000\u0000 \u0000 is asymptotically minimised by the random colouring. Burr and Rosta, extending a famous conjecture of Erdős, conjectured that every graph is common. The conjectures of Erdős and of Burr and Rosta were disproved by Thomason and by Sidorenko, respectively, in the late 1980s. Collecting new examples of common graphs had not seen much progress since then, although very recently a few more graphs were verified to be common by the flag algebra method or the recent progress on Sidorenko’s conjecture. Our contribution here is to provide several new classes of tripartite common graphs. The first example is the class of so-called triangle trees, which generalises two theorems by Sidorenko and answers a question of Jagger, Šťovíček, and Thomason from 1996. We also prove that, somewhat surprisingly, given any tree \u0000 \u0000 \u0000 \u0000$T$\u0000\u0000 \u0000 , there exists a triangle tree such that the graph obtained by adding \u0000 \u0000 \u0000 \u0000$T$\u0000\u0000 \u0000 as a pendant tree is still common. Furthermore, we show that adding arbitrarily many apex vertices to any connected bipartite graph on at most \u0000 \u0000 \u0000 \u0000$5$\u0000\u0000 \u0000 vertices yields a common graph.","PeriodicalId":10513,"journal":{"name":"Combinatorics, Probability & Computing","volume":"77 1","pages":"907-923"},"PeriodicalIF":0.9,"publicationDate":"2020-12-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"83875851","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Lower bound on the size of a quasirandom forcing set of permutations","authors":"Martin Kurečka","doi":"10.1017/S0963548321000298","DOIUrl":"https://doi.org/10.1017/S0963548321000298","url":null,"abstract":"\u0000 A set S of permutations is forcing if for any sequence \u0000 \u0000 \u0000 \u0000${Pi_i}_{i in mathbb{N}}$\u0000\u0000 \u0000 of permutations where the density \u0000 \u0000 \u0000 \u0000$d(pi,Pi_i)$\u0000\u0000 \u0000 converges to \u0000 \u0000 \u0000 \u0000$frac{1}{|pi|!}$\u0000\u0000 \u0000 for every permutation \u0000 \u0000 \u0000 \u0000$pi in S$\u0000\u0000 \u0000 , it holds that \u0000 \u0000 \u0000 \u0000${Pi_i}_{i in mathbb{N}}$\u0000\u0000 \u0000 is quasirandom. Graham asked whether there exists an integer k such that the set of all permutations of order k is forcing; this has been shown to be true for any \u0000 \u0000 \u0000 \u0000$kge 4$\u0000\u0000 \u0000 . In particular, the set of all 24 permutations of order 4 is forcing. We provide the first non-trivial lower bound on the size of a forcing set of permutations: every forcing set of permutations (with arbitrary orders) contains at least four permutations.","PeriodicalId":10513,"journal":{"name":"Combinatorics, Probability & Computing","volume":"55 1","pages":"304-319"},"PeriodicalIF":0.9,"publicationDate":"2020-11-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"89340412","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Tail bounds on hitting times of randomized search heuristics using variable drift analysis","authors":"P. Lehre, C. Witt","doi":"10.1017/s0963548320000565","DOIUrl":"https://doi.org/10.1017/s0963548320000565","url":null,"abstract":"Drift analysis is one of the state-of-the-art techniques for the runtime analysis of randomized search heuristics (RSHs) such as evolutionary algorithms (EAs), simulated annealing, etc. The vast majority of existing drift theorems yield bounds on the expected value of the hitting time for a target state, for example the set of optimal solutions, without making additional statements on the distribution of this time. We address this lack by providing a general drift theorem that includes bounds on the upper and lower tail of the hitting time distribution. The new tail bounds are applied to prove very precise sharp-concentration results on the running time of a simple EA on standard benchmark problems, including the class of general linear functions. On all these problems, the probability of deviating by an r-factor in lower-order terms of the expected time decreases exponentially with r. The usefulness of the theorem outside the theory of RSHs is demonstrated by deriving tail bounds on the number of cycles in random permutations. All these results handle a position-dependent (variable) drift that was not covered by previous drift theorems with tail bounds. Finally, user-friendly specializations of the general drift theorem are given.","PeriodicalId":10513,"journal":{"name":"Combinatorics, Probability & Computing","volume":"38 1","pages":"550-569"},"PeriodicalIF":0.9,"publicationDate":"2020-11-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"89653627","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Photocatalytic Degradation and Antibacterial Study of Copper(II) Mustard Thiourea Complex","authors":"Vandana Sukhadia, Rashmi Sharma, Asha Meena","doi":"10.2174/1877946810666200221122053","DOIUrl":"https://doi.org/10.2174/1877946810666200221122053","url":null,"abstract":"\u0000\u0000The aim of this research work is to synthesise, study and analyse\u0000photocatalytic degradation, kinetics.\u0000\u0000\u0000\u0000Copper(II) mustard thio urea complex has been synthesized and\u0000characterized through FT-IR, NMR, ESR studies.\u0000\u0000\u0000\u0000Photocatalytic degradation of copper(II) mustard thio urea complex was studied\u0000in the presence of ZnO as a catalyst in the solution form, using a non polar solvent benzene\u0000and a polar solvent methanol with different compositions. Antibacterial activities of\u0000copper(II) complex have also been studied against Staphylococcus aureus.\u0000\u0000\u0000\u0000O.D. was measured after different time intervals spectrophotometrically to\u0000measure the degradation of the complex.\u0000\u0000\u0000\u0000Plot of 2+ log O.D. (absorbance) versus time was plotted and found to be linear.\u0000The heterogeneous photocatalysis followed pseudo-first-order reaction kinetics. The present\u0000study suggests that the CMT complex shows antibacterial activity at different concentrations.\u0000\u0000\u0000\u0000The rate of photocatalytic degradation of CMT complex was studied and analyzed.\u0000It has been found that the rate of degradation varies with different parameters like\u0000the concentration of complex, the amount of catalyst, light intensity, solvent polarity etc.\u0000The CMT complex derived from natural mustard oil has shown an inhibitory effect on the\u0000growth of S. aureus which may cause skin diseases.\u0000","PeriodicalId":10513,"journal":{"name":"Combinatorics, Probability & Computing","volume":"10 1","pages":"229-242"},"PeriodicalIF":0.9,"publicationDate":"2020-11-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44898689","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Cetyl Trimethyl Ammonium Bromide as Anti-Pit Agent for Mild Steel in Sulfuric Acid Medium","authors":"H. Kumar, Tilak Dhanda","doi":"10.2174/1877946809666191011162351","DOIUrl":"https://doi.org/10.2174/1877946809666191011162351","url":null,"abstract":"\u0000\u0000Pitting corrosion is a very serious problem for mild steel when it comes in\u0000contact with the dilute sulfuric acid medium. Specialized corrosion inhibitors are essentially\u0000required to minimize pitting and uniform types of corrosion in mild steel.\u0000\u0000\u0000\u0000Most of the corrosion inhibitors discovered so far protects the mild steel from\u0000uniform type of corrosion. But pitting corrosion is more fatal than a uniform type of corrosion\u0000because it immediately makes mild steel unfit for use as leakage starts from the pit.\u0000\u0000\u0000\u0000The objective was to protect the mild steel alloys from pitting corrosion when\u0000comes in contact with dilute sulfuric acid by the use of organic corrosion inhibitor.\u0000\u0000\u0000\u0000 Cetyl Trimethyl Ammonium Bromide (CTAB) is tested as a corrosion inhibitor\u0000for mild steel in 0.1 N H2SO4 as corroding medium at 25.0, 30.0 and 35.0°C by weight\u0000loss, electrochemical polarization, and Impedance spectroscopy methods. Surface study of\u0000corroded and un-corroded specimens of mild steel was carried out by Metallurgical Research\u0000Microscopy (MRM) and Scanning Electron Microscopy (SEM) techniques.\u0000\u0000\u0000\u0000Surface study confirms that the adsorption of CTAB takes place through nitrogen\u0000atom resulting in the formation of uniform, nonporous, passive film confirmed by decrease\u0000in Warburg Impedance (Zw), decrease in Faradaic current, increase in Capacitive current,\u0000an increase in charge transfer resistance, Rct (41 to 401 Ω cm2) and significant increase in\u0000capacitive loop in Nyquist plot with increase in concentration of CTAB which results in\u0000significant decrease in corrosion rate of mild steel in 0.1N H2SO4 medium (percentage corrosion\u0000inhibition efficiency: 95.0%) especially eradicating pitting type of corrosion.\u0000\u0000\u0000\u0000 CTAB was proved to be a very good anti-pit agent for mild steel in 0.1N sulfuric\u0000acid medium. Pitting and uniform type of corrosion was significantly reduced by the\u0000use of CTAB as corrosion inhibitor for mild steel in the dilute sulfuric acid medium at\u000025.0, 30.0 and 35.0°C.\u0000","PeriodicalId":10513,"journal":{"name":"Combinatorics, Probability & Computing","volume":"18 2","pages":"1-14"},"PeriodicalIF":0.9,"publicationDate":"2020-11-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.2174/1877946809666191011162351","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"41293755","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Molecular Interactions within the Crystal Packing of Busulfan (DNA Cross-Linking Agent) by Hirshfeld Surface Analysis","authors":"D. Rajaniverma, D. J. Rao, S. R. Begum, V. Seetaramaiah, Yajjala Ramakrishna, Poonam Tondon, K. Thangavel","doi":"10.2174/1877946809666191115120147","DOIUrl":"https://doi.org/10.2174/1877946809666191115120147","url":null,"abstract":"\u0000\u0000Non-Covalent Interactions (NCIs) play a vital role in the chemical\u0000process. Certain Experimental and theoretical approaches provide information about the\u0000stronger and weaker interactions. In the present work, we have implemented Hirshfeld\u0000charges based surface mapping to find the weaker interactions between the molecules of\u0000busulfan.\u0000\u0000\u0000\u0000The main objective of this work is to recognize the non-covalent interactions\u0000which are not simply drawn from the experimental and conventional theoretical approach.\u0000It aims to provide more insightful information into the crystallographic structure.\u0000\u0000\u0000\u0000In the present work, we have implemented a Hirshfeld surface mapping which\u0000incorporates periodic boundary conditions of the crystalline geometry. Each point of the\u0000isosurface is defined by two distances i.e. de, the distance from the point to the nearest atom\u0000outside to the surface and di, the distance to the nearest atom inside the surface. Also,\u0000for precise identification of intermolecular interactions, mapping by normalized contact\u0000distance dnorm is also considered. Fingerprint plot di vs de for various types of interactions\u0000were also provided.\u0000\u0000\u0000\u0000The Hirshfeld surface and fingerprint plot show the very weak H···H interactions in\u0000addition to the O···H interactions. This enables the visualization of very weak interactions.\u0000\u0000\u0000\u0000 This proposed work on Hirschfeld surface analysis accounts for the solidstate\u0000environment of the busulfan, crystallographic parameters and packing information.\u0000Hence, the interactions obtained for monomer and extended molecular framework in this\u0000work are more reliable to study the intermolecular interactions. The 2D finger print plots\u0000revealed the predominant O⋅⋅⋅H interactions within the crystal packing. In addition to O⋅⋅⋅H\u0000interactions, H⋅⋅⋅H interaction were also identified.\u0000","PeriodicalId":10513,"journal":{"name":"Combinatorics, Probability & Computing","volume":"10 1","pages":"199-205"},"PeriodicalIF":0.9,"publicationDate":"2020-11-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.2174/1877946809666191115120147","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42180930","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"FRET Study Between Carbon Quantum Dots and Malachite Green by Steady-State and Time-Resolved Fluorescence Spectroscopy","authors":"Bipin Rooj, Ankita Dutta, Debojyoti Mukherjee, Sahidul Islam, Ujjwal Mandal","doi":"10.2174/1877946809666191114143123","DOIUrl":"https://doi.org/10.2174/1877946809666191114143123","url":null,"abstract":"\u0000\u0000Understanding the interaction between different organic dyes and\u0000carbon quantum dots helps us to understand several photo physical processes like electron\u0000transfer, energy transfer, molecular sensing, drug delivery and dye degradation processes\u0000etc.\u0000\u0000\u0000\u0000The primary objective of this study is to whether the carbon quantum dots can\u0000act as an electron donor and can participate in the different photo physical processes.\u0000\u0000\u0000\u0000In this work, Carbon Quantum Dots (CQDLs) are synthesized in most economical\u0000and simple carbonization method where petals of Nelumbo nucifera L. are used as a\u0000carbon precursor. The synthesized CQDLs were characterized by using experimental techniques\u0000like UV−Vis absorption, FT-IR, Transmission Electron Microscopy (TEM), steadystate\u0000and time-resolved fluorescence spectroscopy.\u0000\u0000\u0000\u0000The spectral analysis shows that the so synthesized CQDLs are spherical in shape\u0000and its diameter is around 4.2 nm. It shows the fluorescence emission maximum at 495 nm\u0000with a quantum yield of 4%. In this work the interaction between Carbon Quantum Dots\u0000(CQDLs) and an organic dye Malachite Green (MG) is studied using fluorescence spectroscopic\u0000technique under ambient pH condition (At pH 7). The quenching mechanism of\u0000CQDLs with MG was investigated using Stern-Volmer equation and time-resolved fluorescence\u0000lifetime studies. The results show that the dominant process of fluorescence\u0000quenching is attributed to Forster Resonance Energy Transfer (FRET) having a donor acceptor\u0000distance of 53 Å where CQDLs act as a donor and MG acts as an acceptor.\u0000\u0000\u0000\u0000This work has a consequence that CQDLs can be used as a donor species for\u0000different photo physical processes such as photovoltaic cell, dye sensitized solar cell, and\u0000also for antioxidant activity study.\u0000","PeriodicalId":10513,"journal":{"name":"Combinatorics, Probability & Computing","volume":"10 1","pages":"178-188"},"PeriodicalIF":0.9,"publicationDate":"2020-11-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.2174/1877946809666191114143123","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48483537","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Studies on the Temperature Stability of Pure and Doped Triglycine Sulphate Crystals Using TGA/DTA","authors":"V. Padmanabhan, M. Madhu, S. M. Hariharan","doi":"10.2174/1877946810666200212094533","DOIUrl":"https://doi.org/10.2174/1877946810666200212094533","url":null,"abstract":"\u0000\u0000To study the temperature stability of TGS doped with ZnSO4, CdCl2,\u0000BaCl2, and compare it with that of pure TGS.\u0000\u0000\u0000\u0000 Synthesizing pure and doped TGS and studying their temperature dependence\u0000using TGA, DTA, and DSC analysis.\u0000\u0000\u0000\u0000Slow cooling solution growth was used to grow single crystals of pure and\u0000doped TGS. The TGA, DTA and DSC analysis was conducted for determining the temperature\u0000stability.\u0000\u0000\u0000\u0000 The thermal analysis of pure and doped TGS shows that the doped samples show\u0000a similar dependence on temperature as pure TGS. The temperature of decomposition of\u0000pure and doped samples (BTGS, ZTGS, CdTGS) was 226.60°C, 228.38°C, 229.13°C, and\u0000239.13°C respectively. The melting onset of these samples was 214.51°C, 216.04°C,\u0000217.69°C and 216.04°C respectively.\u0000\u0000\u0000\u0000The study shows that doping TGS with the above three described materials\u0000did not alter their temperature stability considerably. It is a good result as doping TGS, for\u0000varying its characteristics like absorbance, reflectance, bandgap energy, etc., which did not\u0000alter its temperature stability. Therefore, TGS doped with the above three dopants can be\u0000used at the same temperature ranges as of pure TGS but with much-improved efficiency.\u0000","PeriodicalId":10513,"journal":{"name":"Combinatorics, Probability & Computing","volume":"10 1","pages":"206-212"},"PeriodicalIF":0.9,"publicationDate":"2020-11-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"41831628","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}