Use and Evaluation of Lignin as Ion Exchangers

Ads, Essam.N.,Nada, A.M.A.,El-Masry, A.M. Korean Chemical Society 2011 대한화학회지 Vol.55 No.1

수산화나트륨과 과산화 무기산을 사용하여 흑색 액체로부터 수산화 리그닌과 과산화 리그닌을 얻었다. 과산화 리그닌을 10% HCl을 사용하여 가수분해하여 가수분해 리그닌을 얻었다. 카르복실화와 인산화과정을 거쳐 카르복시 리그닌과 인산화 리그닌을 얻었다. 에피클로르히드린을 사용하여 가교 리그닌도 얻었다. 이들 얻어진 리그닌들을 적외선분광법, 열김량분석, 시차열분석법으로 분석 하였다. 이들 얻어진 리그닌의 금속이온 흡착효과를 조사하였다. 과산화 리그닌이 수산화된 리그닌 보다 흡착 능력이 우수하였다. Modified lignins were prepared. Soda and peroxy lignins were precipitated from black liquor produced from bagasse pulping with soda and peroxyacid pulping process. The precipitated lignins were hydrolyzed using 10% HCl. Different functional groups were also incorporated into lignin by carboxylation and phosphorylation reactions. Moreover crosslinking of these lignins were carried out using epichlorohydrin. Characterization of the modified lignins and lignins derivative were carried out using Infrared spectroscopy. Thermal analysis of these compounds were also carried out using TGA and DTA techniques. Efficiency of sorption of metal ions by the modified lignin was also investigated. It was found that, the peroxylignin and its derivatives show higher efficiency toward metal ions uptake than the soda lignin.

Use and Evaluation of Lignin as Ion Exchangers

Essam. N. Ads,A. M. A. Nada,A. M. El-Masry 대한화학회 2011 대한화학회지 Vol.55 No.1

Modified lignins were prepared. Soda and peroxy lignins were precipitated from black liquor produced from bagasse pulping with soda and peroxyacid pulping process. The precipitated lignins were hydrolyzed using 10% HCl. Different functional groups were also incorporated into lignin by carboxylation and phosphorylation reactions. Moreover crosslinking of these lignins were carried out using epichlorohydrin. Characterization of the modified lignins and lignins derivative were carried out using Infrared spectroscopy. Thermal analysis of these compounds were also carried out using TGA and DTA techniques. Efficiency of sorption of metal ions by the modified lignin was also investigated. It was found that, the peroxylignin and its derivatives show higher efficiency toward metal ions uptake than the soda lignin.

HOW DO SPLIT QUESTIONNAIRES REDUCE RESPONSE STYLES?

Adıgüzel Feray 글로벌지식마케팅경영학회 2018 Global Marketing Conference Vol.2018 No.07

Lengthy surveys take more time and induce the use of undesired response styles. Response styles generate biases in responses, particularly in lengthy surveys (Baumgartner & Steenkamp, 2001). Response style is defined as tendency to systematically respond to questionnaire items regardless of item content (Baumgartner & Steenkamp, 2001). In practice, market research agencies prefer to use split questionnaires where questionnaires split into parts and each subset is administered to a randomly selected group of respondents (Raghunathan & Grizzle 1995). So far, split questionnaire design literature has been mainly investigated estimation and inference (Lord, 1962; Shoemaker, 1973; Merkouris, 2014; Chipperfield, Barr, & Steel, 2017), data imputation (Raghunathan & Grizzle, 1995; Rässler et al. 2002), and optimal designs (Thomas et al. 2006; Adıgüzel & Wedel 2008; Gonzalez & Eltinge, 2008; Chipperfield & Steel, 2009; Chipperfield & Steel, 2011). Despite split questionnaire is recommended to reduce undesired response styles, its relationship with response styles remains unclear. Two methods of optimal split questionnaire designs were proposed (Adıgüzel & Wedel, 2008): 1) Between-block design: To select entire blocks of questions, 2) Within-block design: To select sets of questions in each block. In this paper, we examine empirically how split designs lessen different type of response styles. Our findings indicate that split questionnaires reduce acquiescence balance, and disacquiescence relative to full questionnaires. The within-block split surveys reduce disacquiescence, acquiescence and balance, whereas the between-block ones did not. Stylistic responding is also influenced by questionnaire satisfaction, attitude, length and mood. Disacquiescence is negatively correlated to mood, questionnaire length and attitude. Midpoint is positively correlated to length, but negatively to questionnaire satisfaction, while acquiescence is opposite for both.

Comparison of mastoid air cell volume in patients with or without a pneumatized articular tubercle

Adışen Mehmet Zahit,Aydoğdu Merve 대한영상치의학회 2022 Imaging Science in Dentistry Vol.52 No.1

Purpose: The aim of this study was to compare mastoid air cell volumes in patients with or without a pneumatized articular tubercle (PAT) on cone-beam computed tomography (CBCT) images. Materials and Methods: The CBCT images of 224 patients were retrospectively analyzed for the presence of PAT. The Digital Imaging and Communications in Medicine data of 30 patients with PAT and 30 individuals without PAT were transferred to 3D Doctor Software. Mastoid air cell volumes were measured using semi-automatic segmentation on axial sections. Data were analyzed using SPSS version 20.0. Results: The patients with PAT and those without PAT had a mean mastoid volume of 6.31±2.86 cm3 and 3.25±1.99 3 , respectively. There were statistically significant differences in mastoid air cell volumes between patients with and cm without PAT regardless of sex and mastoid air cell side (P<0.05). Conclusion: The detection of PAT on routine dental radiographic examinations might be a potential prognostic factor that could be used to detect extensive pneumatization in the temporal bone. Clinicians should be aware that there may be widespread pneumatization of mastoid air cells in patients in whom PAT is detected. Advanced imaging should be performed in these cases, and possible complications due to surgical interventions should be considered.

WHATIF THE FACE OF THE FIRM IS A NARCISSIST CEO? CORPORATE REPUTATION AND FIRM PERFORMANCE

Adıgüzel, Feray,Turner Karynne,Sithu, Jatinder 글로벌지식마케팅경영학회 2018 Global Marketing Conference Vol.2018 No.07

Introduction The attributes of the Chief Executive Officer (CEO) have a significant influence on the actions of the organization and, ultimately, firm performance (Chatterjee & Hambrick, 2007; Kashmiri, Nicol, & Arora, 2017). Recently, there has been growing interest in one particular CEO attribute, i.e., narcissism and how this individual characteristic affects actions taken by the firm and the outcomes achieved. Narcissistic CEOs have been described as “having an inflated self-concept that is enacted through a desire for recognition and a high degree of self-reference when interacting with others (Resick, Whitman, Weingarden, & Hiller, 2009: pg. 1367).” Prior research has found that CEOs with a more narcissistic personality make riskier decisions by changing the company’s strategy more often (Chatterjee & Hambrick, 2007), making acquisitions more frequently and of larger targets (Chatterjee & Hambrick, 2007), adopting discontinuous technologies (Gerstner, König, Enders, & Hambrick, 2013), and expanding international business activities (Oesterle, Elosge, & Elosge, 2016). The results of previous studies show that by pursuing decisions with greater risk and involving the firm in wide-ranging efforts, the actions of narcissistic CEOs lead to fluctuating firm performance (Chatterjee & Hambrick, 2007) and diminishes the positive effect of various firm activities. While these prior studies have provided valuable insight, the strong emphasis on the organizational actions taken as a consequence of the narcissistic CEO has not added to our understanding of the relationship between CEOs who seek personal affirmation, admiration, and attention and important intervening variables for firm performance such as corporate brand reputation. Corporate brand reputation signals the status of an organization and influences the actions of capital markets, investors, consumers, and applicants in the job market (Fombrun & Shanley, 1990). Managers actively work to construct favourable corporate brand reputations through the actions the firm takes and the information selectively released to the media and public. Yet, the literature suggests that narcissistic CEOs spend time focusing on how to enhance their own image rather than on achieving organizational goals (Resick et al., 2009). In this regard, the attention-seeking CEO likely becomes a focal point for the corporate brand. However, no research to date has examined the relationship between the narcissistic CEO’s personality and the effects of corporate brand reputation. This study fills the gap in the literature by investigating how CEO narcissism influences the effectiveness of corporate brand reputation on firm performance. Theoretical development The literature on corporate brands noted that corporate brand reputation is a critical intangible asset that affects firm performance (Roberts & Dowling, 2002). Stakeholders use corporate brand reputation as a means to compare and contrast competitors Researchers have noted various advantages for highly reputable firms: customers are willing to pay more for offerings (Roberts & Dowling, 2002) and accept new product innovations (Dowling, 2002); managers accept lower remuneration (Tavassoli, Sorescu, & Chandy, 2014) and receive higher payoff for investments (Benjamin & Podolny, 1999). These types of advantages allow for greater performance. Thus, consistent with prior literature, we argue the following: Hypothesis 1: Corporate brand reputation has a positive effect on future firm performance. Research has shown that CEO narcissism diminishes the effect of the firm’s positive actions. Petrenko, Aime, Ridge, and Hill (2016) argue that narcissistic CEOs pursue Corporate Social Responsibility efforts (CSR) as a means to enhance their own image. Yet, the authors found that the narcissistic CEOs actually reduce the positive affect of CSR initiatives. Likewise, Engelen, Neumann, and Schmidt (2016) examined the effect CEO narcissism had on the relationship between entrepreneurial orientation and performance finding that CEO narcissism lessens the positive effect of entrepreneurial orientation. These results are due to the narcissistic CEOs perpetual need for attention and self-affirmation which leads to unconcentrated work initiatives and a lack of attention to the needs of employees. When subordinates’ needs are ignored they develop a sense of powerlessness, incompetence and a lack of desire to present their own ideas. This environment diminishes entrepreneurial engagement (Engelen et al., 2016; Wales, Patel, & Lumpkin, 2013). In line with this view, we believe the attention-seeking narcissistic CEO competes with the development of the corporate brand and will dampen the positive effect of highly reputable brands on firm performance. Thus, we argue the following: Hypothesis 2: CEO narcissism diminishes the positive effect of corporate brand reputation on firm performance. Method We compiled a unique unbalanced panel composed of data from COMPUSTAT, ExecuComp, and Fortune Most Admired Companies listing. Our sample includes 993 firm-year observations consists of 237 CEOs from 144 U.S companies on eight-year period, 2009-2016. Data on CEOs were collected from the ExecuComp databases. Financial performance data were from COMPUSTAT. Firm reputation was obtained from firm’s published score in the Fortune “Most Admired Companies” survey in a given year. The fortune rating is obtained through surveys from executives and directors, and has been widely used in previous research (Love, Lim, & Bednar 2017). Our independent and control variables are measured in the year prior to the one in which the survey ratings are published. CEO narcissism is invariant meaning narcissism is a relatively stable disposition similar to Chatterjee and Hambrick’s (2011) and obtained by averaging data from the second and third years of each CEO’s tenure (t + 1 and t + 2). First year of the CEO’s tenure was not considered because of frequently mentioned anomalies reported at first year. CEO narcissism was measured with the same way as Chatterjee and Hambrick’s (2011). Thus, it combines indicators for (1) the prominence of the CEO’s photograph in the company’s annual report; (2) the CEO’s prominence in the company’s press releases; (3) the CEO’s use of first-person singular pronouns in interviews; (4) the CEO’s cash relative pay where cash compensation divided by that of the second-highest paid executive in the firm; and (5) the CEO’s non-cash relative pay where non-cash compensation divided by that of the second-highest-paid executive in the firm. Dependent variables were measures annually and consider available data after the second-year tenure of CEO (n > 2), yielding a 380 firm-years, 61 CEOs for testing our hypothesis. Firm performance was measured with Tobin’s Q (TQ), calculated by dividing the firm’s market value by firm’s asset replacement costs. We have the CEO, the firm, and the industry level control variables. CEO level control variables are CEO age, CEO tenure, CEO gender, CEO stock ownership as the percentage of company stock owned by the CEO, whether the CEO was also board chairman (duality). Firm-level control variables are firm’s the prior year performance, firm size (natural logarithm of revenues t+n–1), firm age, for each dependent variable, to consider strategy or performance tendencies, we included performance value for the firm in the year prior to the start of the CEO’s tenure (t – 1). Industry control variables are dummies for the industry sector (manufacturing, regulated and services industries), the industry average (for all firms in the sample, always excluding the focal firm) in each year (t + n), for each dependent variable to be able to control for industry tendencies. To control for endogeneity i.e. narcissistic CEOs are drawn to certain situations and/or that some conditions, we followed exactly the same procedure of Chatterjee and Hambrick’s (2011). Thus, we regressed CEO narcissism on firm revenues, age, ROA, and calendar year for the year prior to the CEO’s start, ROA change between first and second years of CEO tenure, measures in t+1, namely power (CEO/chair duality and CEO ownership), CEO age, industry dummies. Using the regression coefficients of the significant variables, we calculated each CEO’s predicted narcissism score and included that value as an endogeneity control in our analyses. We used generalized estimating equations (GEE) (Liang & Zeger, 1986), which derive maximum likelihood estimates and accommodate non-independent observations. Due to multiple observations for almost all firms, there is non-independency in our model. We specified a Gaussian (normal) distribution with an identity link function. The covariance structure of the repeated measurement was autoregressive of order one (AR(1)). We used robust variance estimators in our estimations. We used the xtgee routine in Stata 14.2. Results and conclusions The results provide considerable support for hypotheses 1 and 2. Hypothesis 1 predicted that corporate reputation has a positive effect on firm performance (b = .02, p < .01). CEO narcissism is a moderating effect between corporate brand reputation and firm performance. Specifically, CEO narcissism diminishes the positive effect of corporate reputation on firm performance (b = -.04, p < .05). Besides, CEO narcissism have a negative main effect on firm performance (b = -.14, p < .05). Corporate reputation is an intangible asset for firms and positively associated with firm performance according to our results. Little is known so far about the CEO and corporate brand relationship and the role of CEO brands in creating value for the company (Bendisch, Larsen, & Trueman, 2013). We investigated how CEO narcissism influence the relationship between firm’s reputations and firm performance which have not been investigated so far. Since CEOs are the face of the company and it contributes to corporate brand value, narcissistic CEOs might diminish the effect of corporate brand reputation on firm performance with their actions and messages. We find support for our ideas. As a future research, we suggest investigating this issue for different industry sectors and different firm performance measures. Besides, the process of what type of actions of CEOs might diminish brand value should be investigated further. When narcissistic CEOs reduce corporate brand reputation, another potential topic worth to investigate further.

Comparison of postoperative pain intensity after using reciprocating and continuous rotary glide path systems: a randomized clinical trial

Mehmet Adıgüzel,Koray Yılmaz,Pelin Tüfenkçi 대한치과보존학회 2019 Restorative Dentistry & Endodontics Vol.44 No.1

Objectives: The aim of this study was to compare postoperative pain intensity after root canal treatment with One G (OG) vs. R-Pilot (RP) files used for glide path preparation. Materials and Methods: Ninety-three single-canaled mandibular premolar teeth with asymptomatic non-vital pulp were randomly assigned into 3 groups ( n = 31): OG, RP, or without glide path (WGP). After creating the glide path, the root canals were prepared using sequential Mtwo rotary files to size 30/0.05. One endodontic specialist carried out single-visit endodontic treatment. The patients were asked to rate the severity of postoperative pain on a visual analogue scale at 24, 48, and 72 hours after the visit. They were also asked to record their intake of prescribed analgesics taken. The data were analyzed using the χ2, Friedman, Kruskal-Wallis, and Mann-Whitney U tests. Results: In all 3 groups, postoperative pain decreased significantly at each time interval ( p < 0.05). At 24 hours, the OG group had less postoperative pain than the WGP group ( p < 0.05). However, no significant difference was found between the RP group and the others. No statistically significant difference was found among the WGP, OG, and RP groups in postoperative pain intensity at 48 or 72 hours or in analgesic tablet intake at the 3 assessed time intervals. Conclusions: The OG group had less postoperative pain than the WGP group in the first 24 hours. The OG and RP systems were similar regarding postoperative pain intensity and analgesic intake.

Small Angle Neutron Scattering Study of Nanostructural Changes in Microbial Transglutaminase-treated Low-fat Yogurt during Fermentation

Lívia Darnay,Adél Len,Ágota Koncz,László Friedrich,László Rosta 한국식품과학회 2015 Food Science and Biotechnology Vol.24 No.6

Small angle neutron scattering (SANS) studies of fermentation of bovine milk with and without microbial transglutaminase (mTG) are described. Use of mTG increased the quality of low-fat yogurt via cross-linking of milk proteins. The SANS method was suitable for simultaneous characterization of the fermentation process and the effect of mTG. A decrease of whey protein release into the supernatant of centrifuged low-fat yogurt samples showed how mTG was capable to cross-link them already after 1 h of fermentation. The applied SANS method can be used to follow the sol-gel transformation of fermented dairy products in general. Moreover it can be a special tool for detecting the activity of mTG during fermentation of low-fat yogurts.

Ultrasonic preparation of mesoporous silica using pyridinium ionic liquid

László Almásy,Ana-Maria Putz,Adél Len,Catalin Ianăşi,Cecilia Savii 한국화학공학회 2016 Korean Journal of Chemical Engineering Vol.33 No.3

Mesoporous silica matrices have been prepared via classic acid catalyzed and sono-catalyzed sol-gel routes. Tetramethoxysilan (TMOS) and methyl-trimethoxysilane (MTMS) were used as silica precursors, and N-butyl-3-methylpyridinium tetrafluoroborate ([bmPy][BF4]) was employed as co-solvent and pore template. The ionic liquid (IL) to silica mole ratio was varied between 0.007 and 0.07. Nitrogen adsorption-desorption and small-angle neutron scattering measurements were used to characterize the obtained materials. The ionic liquid played the role of catalyst that affected the formation of the primary xerogel particles, and changed the porosity of the materials. Ultrasound treatment resulted in microstructure change on the level of the colloid particle aggregates. In comparison with IL containing xerogels, the IL containing sonogels show increased pore diameter, bigger pore volumes and diminished surface areas.

On the secrecy performance of RIS-enabled wireless communications over Nakagami-m fading channels

Ashutosh K. Yadav,Suneel Yadav,Anshul Pandey,Adão Silva 한국통신학회 2023 ICT Express Vol.9 No.3

This paper examines the secrecy performance of reconfigurable intelligent surface aided wireless communication systems. Specifically, we derive the secrecy outage probability (SOP), intercept probability, probability of non-zero secrecy capacity, and ergodic secrecy capacity (ESC) expressions over Nakagami-m fading channels. We further evaluate the asymptotic SOP expressions to get some insights into the secrecy diversity order under two scenarios of interest; (1) when the signal-to-noise ratio approaches infinity, and (2) when the main-to-eavesdropper ratio tends to infinity. Also, we analytically show the effect of reflecting element density on the ESC performance. The numerical and simulation studies verify our analytical findings.

Surface Properties, Thermal Behavior, and Molecular Simulations of Azo-Polysiloxanes Under Light Stimuli. Insight into the Relaxation

Ana-Maria Resmerita,Luiza Epure,Nicolae Hurduc,Dominique Adès,Alain Siove 한국고분자학회 2010 Macromolecular Research Vol.18 No.8

Light-sensitive materials as azo-polymers have interesting applications in microelectronics, biology, or energy storage, due to their capacity to change their supramolecular ordering. Light-induced modifications result in i) changes in the azobenzene-groups dipole moment due to the trans-cis isomerization, ii) thermal backward cistrans relaxation, and iii) re-ordering of the polymer chain conformation. Conjugation of these phenomena leads to mass transport in the solid state, which is still not well understood. Changes in the surface properties of non-substituted and p-CF3,-CN,-NO2-substituted azophenoxy-polysiloxane films, before and after photo-excitation, were examined. Molecular simulations were performed to evaluate the dipole-moments of the trans and cis p-substituted azobenzene groups and provide a general vision of the spatial arrangement of polymer chains. The role of trans-cis back relaxation and that of the polymer matrix relaxation on the surface and bulk of the materials was discussed. Surface free energy determination of the non-substituted azophenoxy-polysiloxane suggested that the relaxation process is dominated by the thermal slow back-isomerization of the cis fraction and not by the motion of a glassy polymer matrix involving both the surface and bulk. A less clear situation was presented by the semi-crystalline polysiloxanes with electron-withdrawing groups substituted in the para-position. This was attributed mainly to the similar values of the dipole-moment of trans and cis azo-group, the former being slightly more dipolar than the latter.