pH-Sensitive Hydrogels Based on (Meth)Acrylates and Itaconic Acid

Simonida Lj. Tomić,Marija M. Babić,Katarina M. Antić,Jovana S. Jovašević Vuković,Neda B. Malešić,Jovanka M. Filipović 한국고분자학회 2014 Macromolecular Research Vol.22 No.11

Novel hydrogels based on 2-hydroxyethyl methacrylate (HEMA), itaconic acid (IA) and different poly(alkylene glycol) (meth)acrylates (PAGM) (P(HEMA/IA/PAGM)) were synthesized. We investigated the influenceof different PAGM components, with acrylic or methacrylic acid residues in the main chain and ethylene glycol (EG)and/or propylene glycol (PG) units in pendant chains of varying length, on the nature and inherent properties ofP(HEMA/IA/PAGM) copolymeric hydrogels. Swelling studies revealed pH sensitive behavior of P(HEMA/IA/PAGM)samples. Hydrogel structure and morphology were characterized by Fourier transform infrared (FTIR) spectroscopyand scanning electron microscopy (SEM), which confirmed their chemical structure and differences in pore size. The shear modulus values for P(HEMA/IA/PAGM) hydrogels were close to that of PHEMA, but slightly lower thanthe value for P(HEMA/IA). Cephalexin (CEX) drug release profiles from P(HEMA/IA/PAGM) samples showed amarked dependence on the PAGM component. The presence of IA also influenced the release rate of CEX, leadingto a faster release when IA was combined with the more hydrophilic PAGM component. An in vitro assay of P(HEMA/IA/PAGM) cytotoxicity showed good cell viability. The results obtained indicate that P(HEMA/IA/PAGM) hydrogelproperties were significantly dependent on the PAGM component, meaning that the type of side chains can be usedto tune the characteristics of such biomaterials. These properties make P(HEMA/IA/PAGM) copolymeric hydrogelsapplicable in biomedical and biotechnological fields and controlled drug delivery.

Xylella fastidiosa in Europe: From the Introduction to the Current Status

Vojislav Trkulja(Vojislav Trkulja ),Andrija Tomić(Andrija Tomić ),Renata Iličić(Renata Iličić ),Miloš Nožinić(Miloš Nožinić ),Tatjana Popović Milovanović(Tatjana Popović Milovanović ) 한국식물병리학회 2022 Plant Pathology Journal Vol.38 No.6

Xylella fastidiosa is xylem-limited bacterium capable of infecting a wide range of host plants, resulting in Pierce's disease in grapevine, citrus variegated chlorosis, olive quick decline syndrome, peach phony disease, plum leaf scald, alfalfa dwarf, margin necrosis and leaf scorch affecting oleander, coffee, almond, pecan, mulberry, red maple, oak, and other types of cultivated and ornamental plants and forest trees. In the European Union, X. fastidiosa is listed as a quarantine organism. Since its first outbreak in the Apulia region of southern Italy in 2013 where it caused devastating disease on Olea europaea (called olive leaf scorch and quick decline), X. fastidiosa continued to spread and successfully established in some European countries (Corsica and PACA in France, Balearic Islands, Madrid and Comunitat Valenciana in Spain, and Porto in Portugal). The most recent data for Europe indicates that X. fastidiosa is present on 174 hosts, 25 of which were newly identified in 2021 (with further five hosts discovered in other parts of the world in the same year). From the six reported subspecies of X. fastidiosa worldwide, four have been recorded in European countries (fastidiosa, multiplex, pauca, and sandyi). Currently confirmed X. fastidiosa vector species are Philaenus spumarius, Neophilaenus campestris, and Philaenus italosignus, whereby only P. spumarius (which has been identified as the key vector in Apulia, Italy) is also present in Americas. X. fastidiosa control is currently based on pathogen-free propagation plant material, eradication, territory demarcation, and vector control, as well as use of resistant plant cultivars and bactericidal treatments.

Functional and Environmental Advantage of Cleaning Ti5B1 Master Alloy

Aleksandar Mitrašinović,Miloš Tomić 한국정밀공학회 2022 International Journal of Precision Engineering and Vol.9 No.3

One of the greatest environmental goals for the aluminum alloys industry is generating higher quality products by introducing cleaner input materials while maintaining low production costs. A typical dilemma for the master alloy producers is the cleanness level of the master alloy since insoluble inclusions could serve as inoculants during the solidification process. In this work, commercial Ti5B1 master alloy is used for grain refinement of Al7Si4Cu aluminum alloy and compared with the cleaned master alloy that contained a lower amount of residual refractory oxides and salts. Metallography analysis was used for grain size measurement while Computer Aided Cooling Curve Analysis was used for assessment of the undercooling and heat release values. In all instances, specimens treated with the cleaned master alloy showed smaller grains in the final structure and lower undercooling values. The difference in released heat between liquidus and recalescence temperatures was about 25% in specimens where added 0.66 wt% of cleaned master alloys compared to specimens where the commercial master alloys were added. Using cleaner Ti5B1 master alloy with a higher number of TiAl 3 and TiB 2 particles improves its grain refi nementefficiency and transmits fewer impurities in produced parts. Producing cleaner master alloy would be beneficial from economic and environmental aspects by increasing its value and service time of produced parts besides simplifying the recycling process at the end of parts life-cycle.

Global hydroelastic analysis of ultra large container ships by improved beam structural model

Ivo Senjanović,Nikola Vladimir,Marko Tomić,Neven Hadžić,Šime Malenica 대한조선학회 2014 International Journal of Naval Architecture and Oc Vol.6 No.4

Some results on the hydroelasticity of ultra large container ships related to the beam structural modeland restoring stiffness achieved within EU FP7 Project TULCS are summarized. An advanced thin-walled girder theorybased on the modified Timoshenko beam theory for flexural vibrations with analogical extension to the torsionalproblem, is used for formulation of the beam finite element for analysis of coupled horizontal and torsional ship hullvibrations. Special attention is paid to the contribution of transverse bulkheads to the open hull stiffness, as well as tothe reduced stiffness of the relatively short engine room structure. In addition two definitions of the restoring stiffnessare considered: consistent one, which includes hydrostatic and gravity properties, and unified one with geometric stiffnessas structural contribution via calm water stress field. Both formulations are worked out by employing the finiteelement concept. Complete hydroelastic response of a ULCS is performed by coupling 1D structural model and 3Dhydrodynamic model as well as for 3D structural and 3D hydrodynamic model. Also, fatigue of structural elementsexposed to high stress concentration is considered.

Antibacterial Activity of pH-Sensitive Silver(I)/Poly(2-hydroxyethyl acrylate/itaconic acid) Hydrogels

Jovana S. Vuković,Aleksandra A. Perić-Grujić,Dragana S. Mitić-Ćulafić,Biljana Dj. Božić Nedeljković,Simonida Lj. Tomić 한국고분자학회 2020 Macromolecular Research Vol.28 No.4

Since the management of infections becomes prior global healthcare issue, the “post antibiotic era” requires innovative and interdisciplinary approach. As an alternative to widespread and, nowdays mostly uneffective, antibiotic treatment of infections, the series of hydrogels were developed and further investigated as novel antibacterial biomaterials. The hydrogels based on 2-hydroxyethyl acrylate and itaconic acid were synthesized and used for silver(I) ions incorporation. The structural, thermal and swelling characteristics were examined by Fourier transform infrared spectroscopy, differential scanning calorimetry, and swelling study conducted in wide range of pHs at 37 °C. Results confirmed the expected structure, while the glass transition temperatures (Tg) of the hydrogels were detected in range of 10-37 °C. The in vitro release study revealed suitability of these pH sensitive hydrogels as the systems for topical delivery of silver(I) ions. Performed MTT test and Comet assay proved biocompatibility of the hydrogels, as well as the absence of acute genotoxic effect on human fibroblast cells (MRC-5). The hydrogels exhibited satisfying antibacterial activity against methicillin sensitive Staphylococcus aureus (MSSA) and methicillin resistant Staphylococcus aureus (MRSA), indicating the capacity to treat the life-threatening infections.

To compare the pre-lens tear break up time measured at 12 hours for 4 types of daily disposable contact lenses

Tomy Lo Ph.D.,Osbert Chan Ph.D. 대한시과학회 2015 대한시과학회지 학술대회 Vol.2015 No.05

Purpose: Non-invasive tear break up time (NITBUT) is a test commonly used by clinicians to measure the stability of the tear film. This study aims to compare the NITBUT of the Bausch and Lomb Biotrue Oneday (BT) Daily Disposable contact lenses against 3 other commercially available daily disposable lenses to see if BT can provide a more stable pre-lens tear film over the other 3 types of lenses at 12 hours of lens wear. Methods: Twelve existing contact lens wearers were recruited to wear 4 types of contact lenses each for a day of at least 12 hours. Other than BT, the other 3 test lenses were the daily disposable lenses made of etafilcon A (AV), narafilcon A (TE) and delefilcon A (DT1) materials. Each subject was assigned the lenses without knowing the brand of the lenses. Baseline NITBUT was first measured with no lens in the eye and pre-lens NITBUT was measured again at 12 hours after the lenses were worn. The NITBUT was measured using Oculus Keratograph 5M. This instrument measures the NITBUT objectively using infrared illumination which is invisible to the human eye and can prevent glare or bright light irritation during examination. Results: NITBUT was provided by the instrument as “first break” and “average break” values. In this study, the first break value was analyzed because that was the time when the break-up of tears was first detected by the instrument, and that matches with what the clinicians normally do in measuring NITBUT. The NITBUT for the nesofilcon A lens (BT) was longer than that for all the other 3 lens types in 10 out of the 12 subjects (83%). The mean TBUT for BT, AV, TE, DT1 was respectively 17.9 ± 4.3 sec, 9.5 ± 3.3 sec, 8.3 ± 5.9 sec and 8.8 ± 3.6 sec. Not only is the difference in NITBUT statistically significant (p<0.05, paired t-test – nesofilcon A (BT) Vs each of the 3 lens types), but also the NITBUT for BT is about double than that for all the other 3 types of lenses. Conclusion: The NITBUT for the nesofilcon A lens (BT) measured at 12 hours was about double than that for the other 3 lens types and the difference was statistically significant. The results suggested that the Biotrue Oneday provides a more stable pre-lens tear film than the other 3 types of daily disposable lenses at 12 hours of lens wear.

DO CONSUMERS MAKE IMPULSIVE OR REFLECTIVE PURCHASE DECISIONS DURING IMMERSIVE METAVERSE SHOPPING?

Tomi Tonteri,Jani Holopainen,Heli Hallikainen,Tommi Laukkanen 글로벌지식마케팅경영학회 2023 Global Marketing Conference Vol.2023 No.07

Virtual reality (VR) has been set with an expectation of becoming the technology to enable new electronic businesses on metaverse platforms. VR is an application of three-dimensional computer graphics to create a convincing virtual environment where users can interact (Cowan & Ketron, 2019). The most used immersive VR devices are head-mounted displays. Importantly, in addition to visual sense, auditory, haptic, and olfactory senses stimulating devices are used in conjunction with head-mounted displays to reach a multi-sensory VR experience (Xi & Hamari, 2021). VR has been part of the brand strategy for various marketing endeavours (Cowan & Ketron, 2019) such as viewing furniture or kitchen setups by IKEA or creating virtual customer experiences in the real estate sector. However, VR’s impact on the consumer thought model has not been thoroughly examined. This extended abstract contributes to this shortcoming.

Cucumber (Cucumis sativus L.) Fruit and Combination with Losartan Attenuate the Elevation of Blood Pressure in Hypertensive Rats Induced by Angiotensin II

Tomi Hendrayana,Klaudia Yoana,I Ketut Adnyana,Elin Yulinah Sukandar KOREAN PHARMACOPUNCTURE INSTITUTE 2023 Journal of pharmacopuncture Vol.26 No.4

Objectives: Cucumis sativus L. (C. sativus) is vegetable commonly used for managing blood pressure and often consumed in combination with standard antihypertensive therapy, despite lack of scientific evidence supporting their use. Combination of herbs and standard medication could have positive or negative effects. Therefore, this study aimed to evaluate the antihypertensive activity of C. sativus and the combined effect with losartan in the hypertensive rat model induced by angiotensin II. Angiotensin II is a component of the renin-angiotensin-aldosterone system that, upon binding to its receptor, constricts blood vessels leading to elevation of blood pressure. Methods: In an antihypertensive study, rats received C. sativus orally at doses of 9, 18, 27, and 36 mg/kg (full dose); while in a combination study, animals received losartan 2.25 mg/kg combined by either with C. sativus 9 or 18 mg/kg. The standards group received losartan 2.25 mg/kg or 4.5 mg/kg (full dose). Results: Blood pressure was measured using the tail-cuff method. C. sativus significantly attenuated angiotensin II-induced hypertension as observed in groups receiving C. sativus at 9, 18, 27, and 36 mg/kg at 30 minutes after induction showed the average change (Δ) of systolic blood pressure (SBP) and diastolic blood pressure (DBP) with respect to time zero were 28.8/18.3, 24.8/15.8, 22.8/15.5, and 11.5/9.0 mmHg, respectively. Whereas the average change (Δ) of SBP and DBP in the rats receiving the combination of half doses of C. sativus and losartan were 8.8/9.0 mmHg, respectively. These diminished effects were better than a full dose of C. sativus and comparable with a full dose of losartan (6.5/7.8 mmHg). Conclusion: The present findings indicate that C. sativus dose-dependently blocks blood pressure elevation induced by angiotensin II. The combination of half dose of C. sativus and losartan has an additive effect in lowering blood pressure.

제지산업에 있어 원료의 전망 및 미래의 제지 설비 발전 방향

Tomi Ulmanen 한국펄프·종이공학회 1999 펄프.종이기술 Vol.31 No.4

Application of Permanent Magnet Synchronous Machines in Automotive Steering Systems

Tomy Sebastian,Mohammad S. Islam,Sayeed Mir 대한전기학회 2005 KIEE International Transactions on Electrical Mach Vol.5-B No.2