Protein translocation across the ER requires a functional GTP binding site in the alpha subunit of the signal recognition particle receptor

The signal recognition particle (SRP)-mediated translocation of proteins across the RER is a GTP dependent process. Analysis of the primary amino acid sequence of one protein subunit of SRP (SRP54), as well as the alpha subunit of the SRP receptor (SR alpha), has indicated that these proteins contain predicted GTP binding sites. Several point mutations confined to the GTP binding consensus elements of SR alpha were constructed by site specific mutagenesis to define a role for the GTP binding site in SR alpha during protein translocation. The SR alpha mutants were analyzed using an in vitro system wherein SR alpha-deficient microsomal membranes were repopulated with SR alpha by in vitro translation of wild-type or mutant mRNA transcripts. SRP receptors containing SR alpha point mutants were analyzed for their ability to function in protein translocation and to form guanylyl-5\u27-imidodiphosphate (Gpp[NH]p) stabilized complexes with the SRP. Mutations in SR alpha produced SRP receptors that were either impaired or inactive in protein translocation. These SRP receptors were likewise unable to form Gpp(NH)p stabilized complexes with the SRP. One SR alpha point mutant, Thr 588 to Asn 588, required 50- to 100-fold higher concentrations of GTP relative to the wild-type SR alpha to function in protein translocation. This mutant has provided information on the reaction step in protein translocation that involves the GTP binding site in the alpha subunit of the SRP receptor

Wpływ dodatków stopowych Cr i V na mikrostrukturę i właściwości mechaniczne stopu AM60

The paper presents the results of the investigation of the effect of Cr and/or V alloy additions on the microstructure and mechanical properties of the magnesium AM60 alloy. The examinations are performed within the frames of a project aiming at the elaboration of an experimental and industrial technology of producing constructively complex elements of machines and devices made of magnesium alloys with the method of investment casting. It has been proven that small numbers of Cr and V alloy additions improve the strength properties: Rm, A%, and the hardness HB of the obtained casts. The experimental casts were made in ceramic molds.W pracy przedstawiono wyniki badań wpływu dodatków stopowych Cr i/lub V na mikrostrukturę oraz właściwości mechaniczne stopu magnezu AM60. Badania prowadzone są w ramach projektu, którego celem jest opracowanie technologii doświadczalnej i przemysłowej wytwarzania złożonych konstrukcyjnie elementów maszyn i urządzeń ze stopów magnezu metoda wytapianych modeli. Wykazano, że niewielkie ilości dodatków stopowych Cr i V poprawiają właściwości wytrzymałościowe: Rm, A%, oraz twardość HB otrzymanych odlewów. Odlewy doświadczalne wykonano w formach ceramicznych

Cladosporium spores in the air of selected Polish cities in 2015

The aim of the study was to compare the concentration of Cladosporium spores in the cities of Katowice, Cracow, Olsztyn, Piotrkow Trybunalski, Szczecin, Warsaw, and Zielona Gora in 2015. Measurements were performed by the volumetric method (Burkard and Lanzoni pollen and spores sampler). Cladosporium season was defined as the period in which 90% of the annual total catch occurred. The Cladosporium season started first in Zielona Gora on the 27th April and in the other cities it started during the next days. The latest the fungal season started in Szczecin. The number of days with spores count above 2800 spores in 1 m3 ranged from 15 to 63

Odlewanie precyzyjne stopów magnezu o podwyższonych właściwościach

W pracy przedstawiono wybrane aspekty technologii precyzyjnego odlewania stopów magnezu o podwyższonych właściwościach w formach ceramicznych. Przedstawione wyniki badań dotyczą możliwości otrzymywania odlewów ze stopów magnezu o podwyższonych właściwościach mechanicznych i tribologicznych w technologii wytapianych modeli. Poprawę właściwości stopów magnezu uzyskano w wyniku opracowania składu chemicznego nowych stopów magnezu w oparciu o znormalizowane stopy AM60 i AZ91 oraz parametrów ich krystalizacji stosując intensywne studzenie form ceramicznych. W pracy przedstawiono wpływ dodatków chromu lub/i wanadu na mikrostrukturę, charakterystyczne krzywe ATD oraz właściwości mechaniczne oraz tribologiczne badanych stopów. Dodatkowo przedstawiono wyniki badań dotyczące opracowania innowacyjnej technologii nanoszenia inhibitorów na wewnętrzne ściany formy ceramicznej, których zastosowanie pozwoliło na wykonanie odlewów pozbawionych wad powierzchniowych (...).The monograph, based on the author’s original research and ideas, is his contribution to the discipline of Mechanical Engineering. The monograph presents selected aspects of the precision casting technology applied for magnesium alloys with elevated mechanical and tribological properties made in ceramic moulds. The discussed test results concern the possibility of obtaining casts from magnesium alloys with elevated properties in the investment casting technology. An improvement of the magnesium alloy properties was achieved through modification of the chemical composition of normalized alloys AM60 and AZ91 as well as elaboration and application of the technology of intensive cooling of the ceramic moulds. The study demonstrates the effect of chromium and/or vanadium additions on the microstructure, characteristic ATD curves as well as mechanical and tribological properties of the examined alloys. Additionally, the paper presents the test results referring to the elaboration of a technology of preparing ceramic moulds with inhibitors, the application of which made it possible to produce casts without surface defects (...)

Analysis of the crystallization of AZ91 alloy by thermal and derivative analysis method intensively cooled in ceramic shell.

The work presents the test result of the influence of cooling rate on the microstructure of AZ91 alloy, Vickers micro-hardness and Brinell hardness. Studies cooling and crystallization of AZ91 alloy was cast into the ceramic shells pre-heated to 180 ° C and then air-cooled at ambient temperature or intensively super cooled in the liquid coolant. The TDA method was applied to record and characterize the thermal effect resulting from the phase transformations occurring during the crystallization of AZ91 alloy. The kinetics and dynamics of the thermal processes of crystallization of AZ91 alloy in the ceramic shells were determined. Metallographic tests were performed with the use of an optical microscope. A comparison of these test results with the thermal effect recorded by way of the TDA method was made. Influence of cooling rate of AZ91 on HV0, 01 micro-hardness and Brinell hardness alloy was examined

Analiza krystalizacji stopów AM60 i AZ91 w formie ceramicznej metoda analizy termiczno-derywacyjnej (ATD)

The work presents the test results of the crystallisation and cooling of magnesium alloys: AM60 and AZ91, with the use of the TDA method. The tested alloys were cast into ceramic shells heated up to 180 C, produced according to the technology of the shell production in the investment casting method. The TDA method was applied to record and characterize the thermal effect resulting from the phase transformations occurring during the crystallisation of magnesium alloys. The kinetics and dynamics of the thermal processes of the crystallisation of AM60 and AZ91 in the ceramic shells were determined. Metallographic tests were performed with the use of an optical microscope as well as scanning microscopy, together with the EDS chemical analysis of the phases present in the tested casts. A comparison of these test results with the thermal effect recorded by way of the TDA method was made.W pracy przedstawiono wyniki badań krystalizacji i stygnięcia stopów magnezu: AM60 i AZ91 przy użyciu metody ATD. Badane stopy zalewano do form ceramicznych podgrzanych do temperatury 180C, wykonanych zgodnie z technologią wytwarzania form w metodzie traconych modeli. Przy pomocy metody ATD zarejestrowano i wyznaczono charakterystyczne efekty cieplne wynikające z przemian fazowych zachodzących podczas krystalizacji badanych stopów magnezu. Określono kinetykę i dynamikę procesów cieplnych krystalizacji stopów AM60 i AZ91 w formach ceramicznych. Przeprowadzono badania metalograficzne przy pomocy mikroskopu optycznego oraz mikroskopii skaningowej wraz z analizą chemiczną EDS występujących faz w badanych odlewach. Porównano wyniki tych badań z efektami cieplnymi zarejestrowanymi metodą AT

Dynamic evolution of interface roughness during friction and wear processes

Dynamic evolution of surface roughness and influence of initial roughness (Sa=0.282 to 6.73 µm) during friction and wear processes has been analyzed experimentally. The mirror polished and rough surfaces (28 samples in total) have been prepared by surface polishing on Ti-6Al-4V and AISI 1045 samples. Friction and wear have been tested in classical sphere/plane configuration using linear reciprocating tribometer with very small displacement from 130 to 200 microns. After an initial period of rapid degradation, dynamic evolution of surface roughness converges to certain level specific to a given tribosystem. However, roughness at such dynamic interface is still increasing and analysis of initial roughness influence revealed that to certain extent, a rheology effect of interface can be observed and dynamic evolution of roughness will depend on initial condition and history of interface roughness evolution. Multiscale analysis shows that morphology created in wear process is composed from nano, micro and macro scale roughness. Therefore, mechanical parts working under very severe contact conditions, like rotor/blade contact, screws, clutch etc. with poor initial surface finishing are susceptible to have much shorter lifetime than a quality finished parts

Mugwort pollen season in southern Poland and Lviv (Ukraine) in 2015

The aim of the study was to compare the pollen season of the mugwort in Zielona Gora, Opole, Wroclaw, Sosnowiec, Cracow, Lublin, Guciow (Roztocze National Park) and Lviv. Measurements of pollen concentrations were performed with the volumetric method (Burkard or Lanzoni pollen sampler) in Poland and using the Durham trap in Lviv. Maximum pollen concentrations were observed in all measurement sites in the period between 2nd and 15th August. The highest concentration, the highest annual sum of pollen grains, and the highest risk of pollen allergy due of the presence of high concentrations of mugwort pollen grains in the air were recorded in Zielona Gora, Lublin, and Opole

Alternaria spores in the air of selected Polish cities in 2015

The aim of the study was to compare the concentration of Alternaria spores in the cities of Poznan, Bydgoszcz, Sosnowiec, Piotrkow Trybunalski, Olsztyn, Opole, Warsaw, Zielona Gora, Lublin and Szczecin in 2015. Measurements were performed by the volumetric method (Hirst). Alternaria season was defined as the period in which 90% of the annual total catch occurred. The Alternaria season started first in Bydgoszcz on the 27th May and in the other cities it started during the next four weeks. The highest airborne concentration of 900 Alternaria spores × m-3 was noted in Lublin on the 4th July