Search results

Filters

  • Journals
  • Authors
  • Keywords
  • Date
  • Type

Search results

Number of results: 4
items per page: 25 50 75
Sort by:

Abstract

The paper presents results of a study concerning an AlSi7Mg alloy and the effect of subjecting the liquid metal to four different processes: conventional refining with hexachloroethane; the same refining followed by modification with titanium, boron, and sodium; refining by purging with argon carried out in parallel with modification with titanium and boron salts and strontium; and parallel refining with argon and modification with titanium, boron, and sodium salts. The effect of these four processes on compactness of the material, parameters of microstructure, and fatigue strength of AlSi7Mg alloy after heat treatment. It has been found that the highest compactness (the lowest porosity ratio value) and the most favorable values of the examined parameters of microstructure were demonstrated by the alloy obtained with the use of the process including parallel purging with argon and modification with salts of titanium, boron, and sodium. It has been found that in the fatigue cracking process observed in all the four variants of the liquid metal treatment, the crucial role in initiation of fatigue cracks was played by porosity. Application of the process consisting in refining by purging with argon parallel to modification with Ti, B, and Na salts allowed to refine the microstructure and reduce significantly porosity of the alloy extending thus the time of initiation and propagation of fatigue cracks. The ultimate effect consisted in a distinct increase of the fatigue limit value.
Go to article

Abstract

Between 2004 and 2017, multiple studies on the herbicide resistance of weeds were conducted by the Institute of Plant Protection – National Research Institute in Poland. Weed seeds, collected from fields located in various regions of Poland where herbicide use was ineffective, were used in studies conducted under greenhouse conditions. A total of 261 loose silky bent (Apera spica-venti L.) samples were found to be herbicide resistant, which translates to 52.4% of the fields under study. Nearly 50% of the analyzed samples exhibited resistance to sulfonylurea herbicides. Resistance to acetyl CoA carboxylase (ACCase) inhibitors was found in 18 fields, whereas resistance to photosystem II (PSII) inhibitors (isoproturon) was found in 12 fields. Herbicide resistance of blackgrass (Alopecurus myosuroides Huds.) occurred in 26 of the fields under study. In addition, resistance of wild oat (Avena fatua L.) to acetyl CoA carboxylase inhibitors occurred in 10 spring cereal crops. In the case of winter wheat, resistance of cornflower (Centaurea cyanus L.) to tribenuron-methyl occurred in 23 fields. Scentless chamomile (Matricaria inodora L.) and field poppy (Papaver rhoeas L.) were resistant to tribenuron-methyl in four and three fields, respectively, of winter wheat. In the case of sugar beet, three biotypes of fat hen (Chenopodium album L.) and two biotypes of redroot amaranth (Amaranthus retroflexus L.) were resistant to metamitron. Horseweed (Conyza canadensis L.), which grows on railway tracks, exhibited resistance to glyphosate. This paper reviews all studies conducted in Poland on weed resistance. Based on the results, maps of weed resistance in Poland were created.
Go to article

Abstract

This article deals with the effect of manganese that is the most applied element to eliminate the negative effect of iron in the investigated alloy AlSi7Mg0.3. In this time are several methods that are used for elimination harmful effect of iron. The most used method is elimination by applying the additive elements, so-called iron correctors. The influence of manganese on the morphology of excluded ironbased intermetallic phases was analysed at various iron contents (0.4; 0.8 and 1.2 wt. %). The effect of manganese was assessed in additions of 0.1; 0.2; 0.4 and 0.6 wt. % Mn. The morphology of iron intermetallic phases was assessed using electron microscopy (SEM) and EDX analysis. The increase of iron content in investigated alloys caused the formation of more intermetallic phases and this effect has been more significant with higher concentrations of manganese. The measurements carried out also showed that alloys with the same Mn/Fe ratio can manifest different structures and characteristics of excluded iron-based intermetallic phases, which might, at the same time, be related to different resulting mechanical properties.
Go to article

Abstract

This article deals with Janusz Makarczyk’s bestselling historical romance Jafar of Baghdad, first published in 1950. Makarczyk had a varied career as a journalist, travel writer of the ‘globtrotter school’, military officer, diplomat and academic; his deep involvement with the Middle East and Arab history began in the 1926 when he was sent to the Polish consulate in Jerusalem. The life of Jafar ibn Yahya provided him not only with enough material for a gripping story of love and romance but also a pretext for painting a broad canvas of historical events and personages. Addressed to younger readers, the book is didactic in the sense that it offers them basic information about Islam (e.g. the division between the sunni and the shia) as well as lots of facts about the Arab world at the peak of the Abbasid Age (e.g. Harun al-Rashid and the struggle for his succession; rise and fall of the powerful Barmakid family, Harun al-Rashid’s half-sister Abassa; the great Islamic jurists Malik ibn Anas, Muhammad al-Shaybani and Al-Shafi ‘i; an assortment of poets and scholars, including the translator Ibn al-Muqaffa). In addition to countless allusions to the Book of the Thousand Nights and One Night, the narrative is encrusted with explicit and covert quotes from the Qur’an, Arabic adages and proverbs (32), the poems of Abu-l-’Atahiya and Abu Nuwas. The writer is aware that the allusions and learned references need to be contextualized in a way that is functional and that their incorporation into the main text must be handled with maximum flexibility. The great popularity of Jafar of Baghdad in its time can be taken as proof that Makarczyk did succeed in bringing the two functions of his novel, the cognitive and the aesthetic – to instruct and to please – into a harmonious whole.
Go to article

This page uses 'cookies'. Learn more