Role of Diffusion in the Kinetics of Reversible Enzyme-catalyzed Reactions

Szabo, Attila,Zhou, Huan-Xiang Korean Chemical Society 2012 Bulletin of the Korean Chemical Society Vol.33 No.3

The accurate expression for the steady-state velocity of an irreversible enzyme-catalyzed reaction obtained by Shin and co-workers (J. Chem. Phys. 2001, 115, 1455) is generalized to allow for the rebinding of the product. The amplitude of the power-law ($t^{-1/2}$) relaxation of the free- and bound-enzyme concentrations to steady-state values is expressed in terms of the steady-state velocity and the intrinsic (chemical) rate constants. This result is conjectured to be exact, even though our expression for the steady-state velocity in terms of microscopic parameters is only approximate.

Photocatalyst separation from aqueous dispersion using graphene oxide/TiO₂ nanocomposites

Szabo, T.,Veres, A.,Cho, E.,Khim, J.,Varga, N.,Dekany, I. Elsevier 2013 Colloids and surfaces. A, Physicochemical and engi Vol.433 No.-

A series of nanocomposite photocatalysts was prepared from aqueous dispersions of Degussa P25 TiO<SUB>2</SUB> and exfoliated graphite oxide (GO) by heterocoagulation. The structure and catalytic activity of samples in the photooxidation of phenol were characterized in line with their separability by controlled settling experiments at different pHs, irradiation times and mechanical exposure. It was found that single or few-layer graphene oxide sheets were dispersed uniformly in the matrix of titanium dioxide aggregates and were partially reduced to oxygen-containing graphene-like carbon. Although the presence of GO was associated with a loss of photocatalytic efficiency, it has induced an accelerated sedimentation of catalyst slurry as compared to pure TiO<SUB>2</SUB>, resulting in the complete separation of photocatalyst from the treated water in a highly reduced time scale. The loose physical network of weakly adhered particles can be destroyed by sonication or other strong mechanical impacts, but spontaneous aggregation occurs upon mild redispersion. Therefore, heterocoagulation is reversibly induced and can be used to collect the finely suspended catalyst particles worn off from the composite. Extensive reuse of the catalyst without its abrasion and the concomitant need of its post-treatment separation is thus possible. Along with the beneficial sedimentation properties of the composites, this facilitates their use for large scale treatment of waste waters.

Advanced flutter simulation of flexible bridge decks

Szabo, Gergely,Gyorgyi, Jozsef,Kristof, Gergely Techno-Press 2012 Coupled systems mechanics Vol.1 No.2

In this paper a bridge flutter prediction is performed by using advanced numerical simulation. Two novel approaches were developed simultaneously by utilizing the ANSYS v12.1 commercial software package. The first one is a fluid-structure interaction simulation involving the three-dimensional elastic motion of a bridge deck and the fluid flow around it. The second one is an updated forced oscillation technique based on the dynamic mode shapes of the bridge. An aeroelastic wind tunnel model was constructed in order to validate the numerical results. Good agreement between the numerical results and the measurements proves the applicability of the novel methods in bridge flutter assessment.

Long-term clinical and experimental/surface analytical studies of carbon/carbon maxillofacial implants

Szabo, Gyorgy,Barabas, Jozsef,Bogdan, Sandor,Nemeth, Zsolt,Sebok, Bela,Kiss, Gabor Korean Association of Maxillofacial Plastic and Re 2015 Maxillofacial Plastic Reconstructive Surgery Vol.37 No.-

Background: Over the past 30-40 years, various carbon implant materials have become more interesting, because they are well accepted by the biological environment. The traditional carbon-based polymers give rise to many complications. The polymer complication may be eliminated through carbon fibres bound by pyrocarbon (carbon/carbon). The aim of this study is to present the long-term clinical results of carbon/carbon implants, and the results of the scanning electron microscope and energy dispersive spectrometer investigation of an implant retrieved from the human body after 8 years. Methods: Mandibular reconstruction (8-10 years ago) was performed with pure (99.99 %) carbon implants in 16 patients (10 malignant tumours, 4 large cystic lesions and 2 augmentative processes). The long-term effect of the human body on the carbon/carbon implant was investigated by comparing the structure, the surface morphology and the composition of an implant retrieved after 8 years to a sterilized, but not implanted one. Results: Of the 16 patients, the implants had to be removed earlier in 5 patients because of the defect that arose on the oral mucosa above the carbon plates. During the long-term follow-up, plate fracture, loosening of the screws, infection or inflammations around the carbon/carbon implants were not observed. The thickness of the carbon fibres constituting the implants did not change during the 8-year period, the surface of the implant retrieved was covered with a thin surface layer not present on the unimplanted implant. The composition of this layer is identical to the composition of the underlying carbon fibres. Residual soft tissue penetrating the bulk material between the carbon fibre bunches was found on the retrieved implant indicating the importance of the surface morphology in tissue growth and adhering implants. Conclusions: The surface morphology and the structure were not changed after 8 years. The two main components of the implant retrieved from the human body are still carbon and oxygen, but the amount of oxygen is 3-4 times higher than on the surface of the reference implant, which can be attributed to the oxidative effect of the human body, consequently in the integration and biocompatibility of the implant. The clinical conclusion is that if the soft part cover is appropriate, the carbon implants are cosmetically and functionally more suitable than titanium plates.

Does SARS-CoV-2 affect neurodegenerative disorders? TLR2, a potential receptor for SARS-CoV-2 in the CNS

Szabo Marcell P.,Iba Michiyo,Nath Avindra,Masliah Eliezer,Kim Changyoun 생화학분자생물학회 2022 Experimental and molecular medicine Vol.54 No.-

The coronavirus (COVID-19) pandemic, caused by severe acute respiratory system coronavirus 2 (SARS-CoV-2), has created significant challenges for scientists seeking to understand the pathogenic mechanisms of SARS-CoV-2 infection and to identify the best therapies for infected patients. Although ACE2 is a known receptor for the virus and has been shown to mediate viral entry into the lungs, accumulating reports highlight the presence of neurological symptoms resulting from infection. As ACE2 expression is low in the central nervous system (CNS), these neurological symptoms are unlikely to be caused by ACE2-virus binding. In this review, we will discuss a proposed interaction between SARS-CoV-2 and Toll-like receptor 2 (TLR2) in the CNS. TLR2 is an innate immune receptor that recognizes exogenous microbial components but has also been shown to interact with multiple viral components, including the envelope (E) protein of SARS-CoV-2. In addition, TLR2 plays an important role in the pathogenesis of neurodegenerative diseases such as Alzheimer’s disease (AD) and Parkinson’s disease (PD). Based on these observations, we hypothesize that TLR2 may play a critical role in the response to SARS-CoV-2 infiltration in the CNS, thereby resulting in the induction or acceleration of AD and PD pathologies in patients.

서둘러야 할 에너지개발

Szabo Imre 한국원자력산업회의 1990 원자력산업 Vol.10 No.5

Pharmacological Treatment of Alcoholic Hepatitis

( Gyongyi Szabo ) 대한간학회 2020 춘·추계 학술대회 (KASL) Vol.2020 No.1

Severe alcoholic hepatitis (AH) is an acute and often devastating form of alcohol-associated liver disease. Clinically, AH is characterized by elevated bilirubin, MELD >20, and nonspecific symptoms that are caused by underlying inflammation, hepatocyte injury, and impaired intestinal barrier function. Compromised immune defense in AH contributes to infections, sepsis and organ failure. To date, corticosteroids are the only recommended treatment for severe AH, however it does not provide survival benefits beyond one month. Recent preclinical and early clinical studies in AH aided understanding of the disease and presented opportunities for new therapeutic options targeting inflammation, oxidative stress, liver regeneration and modification of intestinal microbiota. In this comprehensive review, we discuss promising preclinical results and ongoing clinical trials evaluating novel therapeutic agents for the treatment of severe AH.

Role of Hepatic Innate Immunity in Hepatic Fibrosis

Gyongyi Szabo 한국간담췌외과학회 2014 한국간담췌외과학회 학술대회지 Vol.2014 No.4

Simulation of photonic crystal waveguides with dispersion

Zsolt Szabo,Gyorgy Kadar,Janos Balazs 한국물리학회 2006 Current Applied Physics Vol.6 No.2

In this paper the nite dierence time domain (FDTD) method is applied to calculate the wave propagation in two dimensionalphotonic crystal optical waveguides and to determine the energy distribution along the propagation path. The band structure isdetermined taking into account the frequency dependence of the dielectric permittivity. Two dimensional photonic crystals basedon bulk and porous silicon material were investigated and a gradual decrease of the averaged energy was found.

Inflammation and Signals in Alcoholic and Non-Alcoholic Fatty Liver Disease

Gyongyi Szabo 한국간담췌외과학회 2014 한국간담췌외과학회 학술대회지 Vol.2014 No.4