Structural Properties of Some C2-Symmetric Schiff Bases and Stereoselectivity in Cyclopropanation of Styrene by Their Cu(I) Complexes

C2-symmetric Schiff bases derived from ñ-camphor and R-fenchone (1-6) were prepared, their configurational and conformational features determined by ID- and 2D-NMR spectra and supported by MM2 calculations. Their Cu(I) complexes prepared in situ were examined in cyclopropanation of styrene and low to medium e.e.\u27s (2-32%) were obtained. Correlation of the structure of E,E-1 and Z,Z-6 with enantioselectivity of their Cu(I) complexes revealed restricting steric requirements in the former, possessing gem dimethyl group in the proximity of the chiral centre, near to the coordination sphere of alkene and carbene, as the probable origin of its higher enantioselectivity

Preparation and Properties of Some Pro chiral and Chiral Precursors of S-3-(3-Hydroxyphenyl)-1-propylpiperidine (S-3-PPP)

Various synthetic approaches to 2,3-dehydro- and 3,4-dehydro-1-propio- nylpiperidines 12,13 and to their 1-propyl congeners 14,15,-two pairs of unsaturated, regioisomeric precursor of S-(-)-3-PPP [S-(-)-3-(3-hydroxyphe- nyl)-l-propylpyperidine, 20] were investigated. Compounds 12 and 13 were prepared by regioselective elimination of water in 11. Preparation of 14 and 15 by two different methods is described. The ratio of the E/Z isomers at the C(0)-N bond in 11-13 was determined by 13C-NMR, and separation of the enantiotopic XH-NMR signals in the enantiomers of 18 and 19 was investigated with chiral shift reagent Eu(tfc>3. Hydrogenation of 15 was performed with five different Rh(l) catalytic complexes, affording the O-methyl-conge- ner of 3-PPP 19. Complete conversion of 15 into 19 was only achieved at elevated temperature and/or pressure to give the R- or S-isomer with low enantioselectivity (7-18% e.e.)

Investigation of Effects of Inhibitor on Corrosion of Carbon Steel in Water with Biocide

U ovom radu istražen je utjecaj komercijalnog inhibitora (Chemtec FI30) na proces korozije ugljičnog čelika P235 u različitim vodenim otopinama; demineraliziranoj i/ili vodovodnoj vodi uz dodatak komercijalnog biocida (Chemtec BI01). Istraživanja su provedena gravimetrijskom metodom i elektrokemijskim metodama, dok je površina ispitivanog materijala analizirana pomoću optičkog mikroskopa. Analize pokazuju da inhibitor smanjuje brzinu korozije ugljičnog čelika u ispitivanim otopinama, ima visoku djelotvornost te da se može svrstati u anodne inhibitore. Također, uočeno je da inhibitor smanjuje opću i jamičastu koroziju ugljičnog čelika u korozivnim vodenim otopinama. Ovo djelo je dano na korištenje pod licencom Creative Commons Imenovanje 4.0 međunarodna.The effect of a commercial inhibitor (Chemtec FI30) on the corrosion of P235 carbon steel in water (demineralised and/or tap water) with the addition of a commercial biocide (Chemtec BI01) was studied in the present work. This study was carried out by weight loss and electrochemical methods, while specimen’s surface was examined using optical microscope. Results obtained from gravimetric measurement revealed that P235 carbon steel corroded in aqueous solution, i.e., in a solution of demineralised and tap water (50 : 50) and a biocide (Fig. 1), and in tap water with a biocide (Fig. 5). By analysing the surface of carbon steel with an optical microscope, general and pitting corrosion was observed, which was more pronounced in tap water with biocide (Figs. 2 and 6). The addition of a commercial inhibitor significantly reduced the occurrence of corrosion damage on the surface of carbon steel (Figs. 3, 4, 7, and 8) and decreased the rate of carbon steel corrosion in all aqueous solutions (Table 1). Electrochemical investigations performed by open circuit potential measurement, linear polarisation and potentiodynamic polarisation measurement showed that the inhibitor Chemtec FI03 shifted the potential to more positive values (Figs. 9 and 10), increased polarisation resistance (Table 3), decreased the rate of carbon steel corrosion, and had high efficiency in all tested solutions (Table 4). The results obtained showed that this commercial inhibitor could be used as an effective inhibitor for the corrosion of carbon steel in aqueous media. This work is licensed under a Creative Commons Attribution 4.0 International License

Karakterizacija β-glukana izoliranih iz pivskoga kvasca te osušenih različitim metodama

Two different procedures have been used for isolation of water-insoluble ß-glucans from brewer’s yeast: alkaline-acidic isolation (AA) and alkaline-acidic isolation with mannoprotein removal (AAM). The obtained ß-glucans were then dried by air-drying, lyophilization and combination of sonication and spray-drying. ß-Glucan preparations obtained by AA and AAM isolations had similar values of dry mass, total polysaccharides, proteins and organic elemental microanalysis. The mass fractions of ß-glucan in total polysaccharides were significantly affected by different isolation procedures. Fourier transform infrared (FTIR) spectra of all preparations had the appearance typical for (1→3)-ß-D-glucan. Lyophilization and especially air-drying caused a higher degree of agglomeration and changes in ß-glucan microstructure. Sonication followed by spray-drying resulted in minimal structural changes and negligible formation of agglomerates.Netopljivi β-glukani izolirani su iz pivskoga kvasca primjenom dvaju različitih postupaka: alkalno-kiselinskog (AK) i alkalno-kiselinskog s uklanjanjem manoproteina (AKM). Dobiveni pripravci β-glukana osušeni su na zraku, liofilizacijom i raspršivanjem uz prethodnu obradu ultrazvukom. Takvi su pripravci, dobiveni AK i AKM postupcima, imali približno iste vrijednosti suhe tvari, ukupnih polisaharida i proteina, te udjele ugljika, dušika i kisika određene organskom mikroanalizom. Na udio β-glukana u ukupnim polisaharidima bitno su utjecali različiti postupci izolacije. FT-IR spektri svih pripravaka imali su izgled tipičan za (1→3)-β-D-glukan. Sušenjem na zraku i liofilizacijom došlo je do značajnih promjena strukture čestica i aglomeracije ß-glukana. Sušenje raspršivanjem uz prethodnu obradu ultrazvukom nije dovelo do stvaranja nakupina čestica kao ni do znatnih promjena njihove strukture

Karakterizacija β-glukana izoliranih iz pivskoga kvasca te osušenih različitim metodama

Two different procedures have been used for isolation of water-insoluble ß-glucans from brewer’s yeast: alkaline-acidic isolation (AA) and alkaline-acidic isolation with mannoprotein removal (AAM). The obtained ß-glucans were then dried by air-drying, lyophilization and combination of sonication and spray-drying. ß-Glucan preparations obtained by AA and AAM isolations had similar values of dry mass, total polysaccharides, proteins and organic elemental microanalysis. The mass fractions of ß-glucan in total polysaccharides were significantly affected by different isolation procedures. Fourier transform infrared (FTIR) spectra of all preparations had the appearance typical for (1→3)-ß-D-glucan. Lyophilization and especially air-drying caused a higher degree of agglomeration and changes in ß-glucan microstructure. Sonication followed by spray-drying resulted in minimal structural changes and negligible formation of agglomerates.Netopljivi β-glukani izolirani su iz pivskoga kvasca primjenom dvaju različitih postupaka: alkalno-kiselinskog (AK) i alkalno-kiselinskog s uklanjanjem manoproteina (AKM). Dobiveni pripravci β-glukana osušeni su na zraku, liofilizacijom i raspršivanjem uz prethodnu obradu ultrazvukom. Takvi su pripravci, dobiveni AK i AKM postupcima, imali približno iste vrijednosti suhe tvari, ukupnih polisaharida i proteina, te udjele ugljika, dušika i kisika određene organskom mikroanalizom. Na udio β-glukana u ukupnim polisaharidima bitno su utjecali različiti postupci izolacije. FT-IR spektri svih pripravaka imali su izgled tipičan za (1→3)-β-D-glukan. Sušenjem na zraku i liofilizacijom došlo je do značajnih promjena strukture čestica i aglomeracije ß-glukana. Sušenje raspršivanjem uz prethodnu obradu ultrazvukom nije dovelo do stvaranja nakupina čestica kao ni do znatnih promjena njihove strukture

Characterization of b-glucans isolated from brewer’s yeast and dried by different methods

Two different procedures have been used for isolation of water-insoluble b-glucans from brewer’s yeast: alkaline-acidic isolation (AA) and alkaline-acidic isolation with mannoprotein removal (AAM). The obtained b-glucans were then dried by air-drying, lyophilization and combination of sonication and spray-drying. b-Glucan preparations obtained by AA and AAM isolations had similar values of dry mass, total polysaccharides, proteins and organic elemental microanalysis. The mass fractions of b-glucan in total polysaccharides were significantly affected by different isolation procedures. Fourier transform infrared (FTIR) spectra of all preparations had the appearance typical for (1®3)-b-D-glucan. Lyophilization and especially air-drying caused a higher degree of agglomeration and changes in b-glucan microstructure. Sonication followed by spray-drying resulted in minimal structural changes and negligible formation of agglomerates

Characterization of ß-Glucans Isolated from Brewer’s Yeast and Dried by Different Methods

Two different procedures have been used for isolation of water-insoluble ß-glucans from brewer’s yeast: alkaline-acidic isolation (AA) and alkaline-acidic isolation with mannoprotein removal (AAM). The obtained ß-glucans were then dried by air-drying, lyophilization and combination of sonication and spray-drying. ß-Glucan preparations obtained by AA and AAM isolations had similar values of dry mass, total polysaccharides, proteins and organic elemental microanalysis. The mass fractions of ß-glucan in total polysaccharides were significantly affected by different isolation procedures. Fourier transform infrared (FTIR) spectra of all preparations had the appearance typical for (1→3)-ß-D-glucan. Lyophilization and especially air-drying caused a higher degree of agglomeration and changes in ß-glucan microstructure. Sonication followed by spray-drying resulted in minimal structural changes and negligible formation of agglomerates

Personality and work behavior: Nature and measurement of socially desirable responding

Glavni prigovor valjanosti i primjenjivosti upitnika ličnosti u selekcije svrhe je njihova podložnosti lažiranju odgovora, odnosno namjernom davanju socijalno poželjnih odgovora. Posljednjih desetljeća proveden je niz istraživanja kojima se pokušalo utvrditi kakva je priroda socijalno poželjnog odgovaranja i koji su načini njegova mjerenja. Od početne konceptualizacije prema kojoj se socijalno poželjno odgovaranje izjednačava s namjernim iskrivljavanjem odgovora na upitnicima ličnosti, socijalna poželjnost je evoluirala u višedimenzionalni konstrukt. Prema trenutačno najutjecajnijem modelu (Paulhus, 2002, 2006) socijalno poželjno odgovaranje je moguće razmatrati na dvije razine: procesnoj i sadržajnoj. Na procesnoj razini razlikujemo svjesno upravljanje dojmovima i nesvjesno samoosnaživanje, a na sadržajnoj egoističko pretjerivanje u vlastitoj kognitivnoj i socijalnoj kompetentnosti te moralističko negiranje društveno nepoželjnih impulsa i isticanje atributa svetosti. S obzirom da su provjere novog modela vrlo oskudne, osnovni cilj istraživanja opisanog u ovoj knjizi bio je provjeriti njegove temeljne pretpostavke koristeći različite indikatore socijalno poželjnog odgovaranja. Istraživanje smo proveli na prigodnom uzorku ispitanika završnih godina studija i netom diplomiranih (N=345). U istraživanju su korištena tri upitnika: Sveobuhvatni inventar socijalno poželjnog odgovaranja (CIDR) namijenjen mjerenju komponenti Paulhusovog modela, petfaktorski upitnik ličnosti (IPIP-300) te Upitnik pretjeranih tvrdnji (OCQ- 150) namijenjen mjerenju precjenjivanja vlastitog znanja. Ispitanici su sva tri upitnika najprije ispunjavali u iskrenoj situaciji odgovaranja, a zatim je polovica ispitanika CIDR i IPIP-300 ispunjavala u situaciji poticanog egoističkog iskrivljavanja, a druga polovica ispitanika ih je ispunjavala u situaciji poticanog moralističkog iskrivljavanja. Rezultati provedenih analiza nisu potvrdili model ni na procesnoj, ni na sadržajnoj razini. Na procesnoj razini, suprotno očekivanjima, rezultati nisu opravdali razlikovanje nesvjesnog i svjesnog socijalno poželjnog odgovaranja jer su se u situacijama poticanog iskrivljavanja rezultati na skalama osnaživanja povećali, jednako kao i rezultati na skalama upravljanja dojmovima. Osim toga, komponente socijalne poželjnosti nisu na očekivan način korelirale s direktnim mjerama iskrivljavanja odgovora na upitniku ličnosti i rezultatom na upitniku pretjeranih tvrdnji. Na sadržajnoj razini, osim osobine ugodnosti, obrazac promjena na skalama CIDR-a i upitnika ličnosti nije bio sukladan pretpostavkama modela. Generalno, dobiveni rezultati pokazuju da skale socijalno poželjnog odgovaranja, razvijene u okviru Paulhusovog modela, nisu dobra mjera socijalno poželjnog odgovaranja. Stoga bi se buduće provjere modela trebale temeljiti ili na valjanijim skalama i/ili na alternativnim metodama mjerenja socijalno poželjnog odgovaranja