• Journal of Environmental Science International
• /
• v.17 no.3
• /
• pp.351-357
• /
• 2008

In order to develope an efficient way for the synthesis of highly pure 1,4-sorbitan solution from sorbitol, some experimental studies were performed. The reaction showed first order reaction with activation energy of 118.3 KJ/mol. Color of the product solutions changed to brown with reaction temperature and reaction time. The equilibrium contents of 1,4-sorbitan increased with decrease in reaction pressure, but the content of major impurity, sorbide, showed maximum about 550 torr vacuum with $H_3PO_4$ catalyst. The reasonable catalyst configuration was 0.26 wt% PTSA and 1 wt% $H_3PO_2$ and optimum reaction temperature and pressure range was $110\sim120^{\circ}C$ and $700\sim720$ torr vacuum, respectively. At optimum reaction conditions, we could obtain white product solutions of highly pure 1,4-sorbitan with sorbide less than 10 wt%. This white product solution is advantageous for preparation of high quality span, anti-fogging agent.

• Journal of Microbiology and Biotechnology
• /
• v.18 no.1
• /
• pp.124-127
• /
• 2008

The behavior of Penicillium camembertii and Geotrichum candidum growing in submerged pure cultures on simple (glutamate) or complex (peptones) substrates as nitrogen and carbon sources and lactate as a second carbon source was examined. Similar to the behavior previously recorded on a simple substrate (glutamate), a clear differentiation between the carbon source and the energy source was also shown on peptones and lactate during P. camembertii growth, since throughout growth, lactate was only dissimilated, viz., used for energy supply by oxidation into $CO_2$, whereas peptides and amino acids from peptones were used for carbon (and nitrogen) assimilation. Because of its deaminating activity, G candidum preferred peptides and amino acids to lactate as energy sources, in addition to being assimilated as carbon and nitrogen sources. From this, on peptones and lactate, G candidum grew faster than P. camembertii (0.19 and 0.08 g/l/h, respectively) by assimilating the most readily utilizable peptides and amino acids; however, owing to its lower proteolytic activity, the maximum biomass was lower than that of P. camembertii (3.7 and 5.5 g/l, respectively), for which continuous proteolysis and assimilation of peptides were shown.

• Journal of Microbiology and Biotechnology
• /
• v.26 no.1
• /
• pp.80-88
• /
• 2016

The enzyme-catalyzed Henry reaction was realized using deep eutectic solvents (DESs) as a reaction medium. The lipase from Aspergillus niger (lipase AS) showed excellent catalytic activity toward the substrates aromatic aldehydes and nitromethane in choline chloride:glycerol at a molar ratio of 1:2. Addition of 30 vol% water to DES further improved the lipase activity and inhibited DES-catalyzed transformation. A final yield of 92.2% for the lipase AS-catalyzed Henry reaction was achieved under optimized reaction conditions in only 4 h. In addition, the lipase AS activity was improved by approximately 3-fold in a DES-water mixture compared with that in pure water, which produced a final yield of only 33.4%. Structural studies with fluorescence spectroscopy showed that the established strong hydrogen bonds between DES and water may be the main driving force that affects the spatial conformation of the enzyme, leading to a change in lipase activity. The methodology was also extended to the aza-Henry reaction, which easily occurred in contrast to that in pure water. The enantioselectivity of both Henry and aza-Henry reactions was not found. However, the results are still remarkable, as we report the first use of DES as a reaction medium in a lipase-catalyzed Henry reaction.

• Bulletin of the Korean Mathematical Society
• /
• v.51 no.4
• /
• pp.1145-1153
• /
• 2014

Let G be a finite group and X be a union of conjugacy classes of G. Define C(G,X) to be the graph with vertex set X and $x,y{\in}X$ ($x{\neq}y$) joined by an edge whenever they commute. In the case that X = G, this graph is named commuting graph of G, denoted by ${\Delta}(G)$. The aim of this paper is to study the automorphism group of the commuting graph. It is proved that Aut(${\Delta}(G)$) is abelian if and only if ${\mid}G{\mid}{\leq}2$; ${\mid}Aut({\Delta}(G)){\mid}$ is of prime power if and only if ${\mid}G{\mid}{\leq}2$, and ${\mid}Aut({\Delta}(G)){\mid}$ is square-free if and only if ${\mid}G{\mid}{\leq}3$. Some new graphs that are useful in studying the automorphism group of ${\Delta}(G)$ are presented and their main properties are investigated.

• Bulletin of the Korean Mathematical Society
• /
• v.55 no.1
• /
• pp.187-204
• /
• 2018

Let $R={\bigoplus}_{{\alpha}{\in}{\Gamma}}\;R_{\alpha}$ be a graded integral domain, H be the set of nonzero homogeneous elements of R, and ${\star}$ be a semistar operation on R. The purpose of this paper is to study the properties of $quasi-Pr{\ddot{u}}fer$ and UMt-domains of graded integral domains. For this reason we study the graded analogue of ${\star}-quasi-Pr{\ddot{u}}fer$ domains called $gr-{\star}-quasi-Pr{\ddot{u}}fer$ domains. We study several ring-theoretic properties of $gr-{\star}-quasi-Pr{\ddot{u}}fer$ domains. As an application we give new characterizations of UMt-domains. In particular it is shown that R is a $gr-t-quasi-Pr{\ddot{u}}fer$ domain if and only if R is a UMt-domain if and only if RP is a $quasi-Pr{\ddot{u}}fer$ domain for each homogeneous maximal t-ideal P of R. We also show that R is a UMt-domain if and only if H is a t-splitting set in R[X] if and only if each prime t-ideal Q in R[X] such that $Q{\cap}H ={\emptyset}$ is a maximal t-ideal.

• Speech Sciences
• /
• v.12 no.2
• /
• pp.101-108
• /
• 2005

Apraxia of phonation (AOP) has often been described as a feature of apraxia of speech or of severe non-fluent type of aphasia. Pure AOP is rare and, to our knowledge, only two cases have been reported. Brain lesion sites of the reported cases were not those sites known to be responsible for apraxia of speech. This study presents a case of AOP which resulted from the secondary stroke in the left corona radiata immediately following the first stroke in the left temporoparietal lobe. A 61-year old right-handed man shwoed a global type of aphasia after the first cerebral infarction, but was able to generate spontaneously some short fragments of speech. On the day after the first infarction, he suffered from the secondary infarction, leaving him a complete loss of voluntary phonation. He did not showed any significant change in language functions. Several occurrences of involuntary phonation were observed upon laughing or crying. He was also able to cough unintentionally. A vidoe-stroboscopic examination failed to reveal any evidence of structural and functional impairment in larynx. Although this case is not of pure form of AOP, AOP appeared after the secondary stroke without significant changes of language impairment since the first stroke. Therefore, AOP may be a consequence of the brain lesion from the secondary stroke even though we cannot rule out the possibility of an additive effect of the secondary to the first stroke.

• Journal of the Korean Mathematical Society
• /
• v.49 no.1
• /
• pp.85-98
• /
• 2012

Let R be a commutative ring and I its proper ideal, let S(I) be the set of all elements of R that are not prime to I. Here we introduce and study the total graph of a commutative ring R with respect to proper ideal I, denoted by T(${\Gamma}_I(R)$). It is the (undirected) graph with all elements of R as vertices, and for distinct x, y ${\in}$ R, the vertices x and y are adjacent if and only if x + y ${\in}$ S(I). The total graph of a commutative ring, that denoted by T(${\Gamma}(R)$), is the graph where the vertices are all elements of R and where there is an undirected edge between two distinct vertices x and y if and only if x + y ${\in}$ Z(R) which is due to Anderson and Badawi [2]. In the case I = {0}, $T({\Gamma}_I(R))=T({\Gamma}(R))$; this is an important result on the definition.

• Bulletin of the Korean Mathematical Society
• /
• v.56 no.4
• /
• pp.1041-1057
• /
• 2019

Let ${\Gamma}$ be a nonzero commutative cancellative monoid (written additively), $R={\bigoplus}_{{\alpha}{\in}{\Gamma}}$ $R_{\alpha}$ be a ${\Gamma}$-graded integral domain with $R_{\alpha}{\neq}\{0\}$ for all ${\alpha}{\in}{\Gamma}$, and $S(H)=\{f{\in}R{\mid}C(f)=R\}$. In this paper, we study homogeneously divisorial domains which are graded integral domains whose nonzero homogeneous ideals are divisorial. Among other things, we show that if R is integrally closed, then R is a homogeneously divisorial domain if and only if $R_{S(H)}$ is an h-local $Pr{\ddot{u}}fer$ domain whose maximal ideals are invertible, if and only if R satisfies the following four conditions: (i) R is a graded-$Pr{\ddot{u}}fer$ domain, (ii) every homogeneous maximal ideal of R is invertible, (iii) each nonzero homogeneous prime ideal of R is contained in a unique homogeneous maximal ideal, and (iv) each homogeneous ideal of R has only finitely many minimal prime ideals. We also show that if R is a graded-Noetherian domain, then R is a homogeneously divisorial domain if and only if $R_{S(H)}$ is a divisorial domain of (Krull) dimension one.

• Membrane and Water Treatment
• /
• v.14 no.1
• /
• pp.11-18
• /
• 2023

This work addresses the development of microfiltration ceramic membrane from alumina using extrusion method. The membranes were sintered at different temperatures ranging between 1000 and 1300℃. The alumina was characterized with thermogravimetric analysis, particle size distribution, X-ray diffraction, Fourier transform infrared spectrometer and scanning electron microscope analysis. Subsequently, the effect of sintering temperature on the membrane properties such as porosity, flexural strength, and pure water permeability was investigated and optimized for the sintering temperature. It is observed that with increasing sintering temperature, the porosity of the membranes decreases and the flexural strength, and pure water permeability of the membranes increase. The uncoated and coated membranes were compared at constant flux mode of filtration. Under the turbidity solution recirculation alone at 100 NTU, trans-membrane pressure (TMP) of uncoated membrane remained constant when the filtration flux was below 121 Lm^-2 h ^-1 , while the coated membrane was 111 Lm_-2 h ^-1 . Although suction pressure increased more rapidly at higher turbidity, coated membrane filtration showed better removal efficiency of the turbidity.

• Microbiology and Biotechnology Letters
• /
• v.51 no.1
• /
• pp.69-82
• /
• 2023

Nitrilases are a hydrolase group of enzymes that catalyzes nitrile compounds and produce industrially important organic acids. The current objective is to optimize nitrilase production using statistical methods assisted with artificial intelligence (AI) tool from novel nitrile degrading isolate. A nitrile hydrolyzing bacteria Bacillus subtilis AGAB-2 (GenBank Ascension number- MW857547) was isolated from industrial effluent waste through an enrichment culture technique. The culture conditions were optimized by creating an orthogonal design with 7 variables to investigate the effect of the significant factors on nitrilase activity. On the basis of obtained data, an AI-driven support vector machine was used for the fitted regression, which yielded new sets of predicted responses with zero mean error and reduced root mean square error. The results of the above global optimization were regarded as the theoretical optimal function conditions. Nitrilase activity of 9832 ± 15.3 U/ml was obtained under optimized conditions, which is a 5.3-fold increase in compared to unoptimized (1822 ± 18.42 U/ml). The statistical optimization method involving Plackett Burman Design and Response surface methodology in combination with an AI tool created a better response prediction model with a significant improvement in enzyme production.