Zvi C. Koren

Zvi C. Koren

orcid

Research Focus & Metrics

Academic Career Length

20Years (2007-Present)

(Calculated once Scilit publication data is synced: current year − year of first publication + 1)

Representative Publications

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29 October 2007 in Microchimica Acta
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ZKZvi C. Koren
Zvi C. Koren

1 September 2021 in Microporous and Mesoporous Materials
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Journal Article
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PMPiotr Miądlicki
Piotr Miądlicki
AWAgnieszka Wróblewska
Agnieszka Wróblewska
KKKarolina Kiełbasa
Karolina Kiełbasa
ZKZvi C. Koren
Zvi C. Koren
Beata MichalkiewiczBeata Michalkiewicz
Beata Michalkiewicz

11 March 2015 in Journal of Porous Materials
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Beata MichalkiewiczBeata Michalkiewicz
Beata Michalkiewicz
ZKZvi C. Koren
Zvi C. Koren

27 April 2019 in Catalysts
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AWAgnieszka Wróblewska
Agnieszka Wróblewska
PMPiotr Miądlicki
Piotr Miądlicki
JTJadwiga Tołpa
Jadwiga Tołpa
Joanna Sreńscek-NazzalJoanna Sreńscek-Nazzal
Joanna Sreńscek-Nazzal
ZKZvi C. Koren
Zvi C. Koren
Beata MichalkiewiczBeata Michalkiewicz
Beata Michalkiewicz
Titanium-containing mesoporous silica catalysts with different Ti contents were prepared by the sol–gel method, whereby the molar ratios of silicon to titanium in the crystallization gel amounted to, respectively, 40:1, 30:1, 20:1 and 10:1. The produced Ti-MCM-41 materials were characterized by the following instrumental methods: XRD, UV-Vis, FT-IR, SEM, and XRF. Textural parameters were also determined for these materials by means of the N2 adsorption/desorption method. The activities of these catalysts were investigated in the α-pinene isomerization process. The most active catalyst was found to be the material with the molar ratio of Si:Ti equal to 10:1, which contained 12.09 wt% Ti. This catalyst was used in the extended studies on the α-pinene isomerization process, and the most favorable conditions for this reaction were found to be temperature of 160 °C, reaction time of 7 h, with the catalyst composition of 7.5 wt% relative to α-pinene. These studies showed that the most active catalyst, at the best reaction conditions, allowed for the attainment of 100% conversion of α-pinene over a period of 7 h. After this time the selectivities (in mol%) of the main products were as follows: camphene (35.45) and limonene (21.32). Moreover, other products with lower selectivities were formed: γ-terpinene (4.38), α-terpinene (8.12), terpinolene (11.16), p-cymene (6.61), and α-phellandrene (1.58).

4 July 2024 in Antioxidants
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JGJadwiga Grzeszczak
Jadwiga Grzeszczak
AWAgnieszka Wróblewska
Agnieszka Wróblewska
AKAdam Klimowicz
Adam Klimowicz
SGSylwia Gajewska
Sylwia Gajewska
ŁKŁukasz Kucharski
Łukasz Kucharski
KJKatarzyna Janda-Milczarek
Katarzyna Janda-Milczarek
α-Pinene is the bicyclic, unsaturated terpene hydrocarbon present in many plants. Due to its beneficial chemical properties, this compound is of great interest and has found numerous applications as a raw material in many chemical industries as well as in medicine and cosmetics. The aim of this study was to evaluate the antioxidant activities of ethanolic extracts obtained from plants containing α-pinene and to test the properties of cosmetic emulsions prepared with these extracts. The raw plant materials consisted of fresh parts of Pinus sylvestris L., such as cones, needles, and branches, as well as dried unground and ground pinecones; dried and fresh Rosmarinus officinalis leaves; dried Levisticum officinale leaves; and dried Salvia officinalis L. leaves. The plant materials were individually extracted with 40% (v/v), 70% (v/v), and 96% (v/v) ethanol using ultrasound-assisted extraction (UAE) for 15, 30, or 60 min. This method is a green extraction technique, frequently applied to isolate active substances from plants. For the selected plant materials, Soxhlet extraction with 96% (v/v) ethanol was also performed. The qualitative and quantitative analyses of the components in the selected extracts were performed with gas chromatography coupled with mass spectrometry (GC-MS). The antioxidant activities of the extracts were evaluated with the DPPH and ABTS methods. The extracts of three plant materials with the highest antioxidant activities—dried Rosmarinus officinalis leaves, dried Salvia officinalis L. leaves, and dried and ground Pinus sylvestris L. cones—were selected to be incorporated in cosmetic emulsions containing glyceryl monostearate and Olivem 1000 as emulsifiers. The stabilities and antioxidant activities of the emulsions were evaluated. Moreover, the antimicrobial properties of the emulsions using microbiological tests were also determined. The findings suggest that the prepared emulsions are stable cosmetic products with a high antioxidant potential.

19 November 2016 in Catalysis Letters
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AWAgnieszka Wróblewska
Agnieszka Wróblewska
EKEDYTA KUCHARSKA
EDYTA KUCHARSKA
JMJacek Młodzik
Jacek Młodzik
ZKZvi C. Koren
Zvi C. Koren
Beata MichalkiewiczBeata Michalkiewicz
Beata Michalkiewicz
Iron/nanoporous carbon catalysts (Fe/NPC) were used in the studies on limonene oxidation employing methanol as a solvent and aqueous hydrogen peroxide as an oxidizing agent. The nanoporous carbon support of the catalyst was produced from molasses, a sugar refinery waste product. To the best of our knowledge, there are no reports on the preparation of nanoporous carbon from molasses. The content of iron in the Fe/NPC catalysts studied included 0.68, 1.32 and 2.64 wt% Fe. The products of the limonene oxidation process were 1,2-epoxylimonene and its diol, carveol and perillyl alcohol, which are compounds with a large number of applications. The conversion of limonene reached 60 mol%. The “pure” NPC material was also active in the oxidation process. The utilized catalytic system is simple and cheap, and the use of environmentally-friendly H2O2 and the natural product limonene signify that this process can be considered as a “green process”. The results of the current research indicate that the utilization of molasses for the preparation of the carbonaceous catalysts active in the limonene oxidation is feasible, and these catalysts could be used in numerous industrial oxidation processes.