• Bulletin of the Korean Chemical Society
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• 제35권5호
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• pp.1440-1448
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• 2014

Co(II)-tetrasulfonated phthalocyanine (CoTSP) is known to be aggregated to dimer at high concentration levels in water. A study on the aggregation of CoTSP using multivariate curve resolution analysis of the visible absorbance spectra over a concentration range of 30, 40 and 50 ${\mu}M$ in the presence of dimethyl sulfoxide (DMSO), dimethyl formamide (DMF), acetonitrile (AN) and ethanol (EtOH) in the concentration range of 0 to 3.57 M is conducted. A hard modeling-based multivariate curve resolution method was applied to determine the dissociation constants of the CoTSP aggregates at various temperatures ranging from 25, 45 and $65^{\circ}C$ and in the presence of various co-solvents. Dissociation constant for aggregation was increased and then decrease by temperature and concentration of phthalocyanine, respectively. Utilizing the vant Hoff relation, the enthalpy and entropy of the dissociation equilibriums were calculated. For the dissociation of both aggregates, the enthalpy and entropy changes were positive and negative, respectively. Molecular dynamics simulation of cosolvent effect on CoTSP aggregation was done to confirm spectroscopy results. Results of radial distribution function (RDF), root mean square deviation (RMSD) and distance curves confirmed more effect of polar solvent to decrease monomer formation.

• 한국근적외분광분석학회:학술대회논문집
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• 한국근적외분광분석학회 2001년도 NIR-2001
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• pp.1284-1284
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• 2001

The transesterification of molten ethylene/vinylacetate (EVA) copolymers by octanol as a reagent and sodium methoxide as a catalyst in an extruder has been monitored by on-line near infrared (NIR) spectroscopy. A total of 60 NIR spectra were acquired for 37 minutes with the last spectrum recorded 31 minutes after the addition of octanol and catalyst was stopped. The experimental spectra show strong baseline fluctuations which are corrected for by multiplicative scatter correction (MSC). The chemometric methods of orthogonal projection approach (OPA) and multivariate curve resolution (MCR) were used to resolve the spectra and to derive concentration profiles of the species. The detailed analysis reveals the absence of completely pure variables that leads to small errors in the calculation of pure spectra. The initial estimation of a concentration that is necessary as an input parameter for MCR also presents a non-trivial task. We obtained results that were not ideal but applicable for practical concentration control. They enable a fast monitoring of the process in real-time and resolve the spectra of the EVA copolymer and the ethylene/vinyl alcohol (EVAL) copolymer to be very close to the reference spectra. The chemometric methods used and the decomposed spectra are discussed in detail.

• 대한환경공학회지
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• 제39권7호
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• pp.426-439
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• 2017

이 총설은 근권에서 일어나는 유기산, 산화음이온, 그리고 금속 산화물 간의 상호작용을 이해하는데 활용하고 있는 적외선 분광학과 계산화학에 대한 기본적 원리, 역사, 적용 분야, 장점, 그리고 단점에 대해 최근 연구들을 바탕으로 요약하였다. 식물의 유기산과 금속 산화물은 토양 환경에서 산화음이온의 유효도와 이동성을 결정하기 때문에, 산화음이온의 환경 내 거동을 이해하기 위해서는 계면에서 이들의 상호작용을 이해하는 것이 중요하다. 적외선 분광학의 감쇠 전반사 기법은 계면에서 일어나는 화학적인 반응을 측정하는 강력한 도구이지만, 광학적 특성들이 실험 설계와 대상에 따라 매우 다르게 나타날 수 있으므로 이를 이용한 측정은 까다롭다. 전반사에 의해 발생하는 소멸파의 침투 깊이가 가장 중요한 매개 변수인데, 침투 깊이는 적외선의 입사각과 대상 파장, 그리고 매질의 굴절률에 따라 결정된다. 또한, 적외선을 이용하여 계면에서의 화학반응을 분석할 때 겹쳐서 발생하는 스펙트럼을 해석하는 것 역시 큰 문제이기 때문에, 겹쳐 나타나는 스펙트럼을 해석하여 밴드를 검출하고, 이 스펙트럼을 deconvolution하는 것이 필수적이다. 본 총설에서는 적외선스펙트럼을 처리하는 기본적인 절차와, 밴드 검출에 사용하는 네가지 방법인 도함수 분광학과 이차 상관 분광학, multivariate curve resolution, 계산 화학을 액체상에 존재하는 인산염 종분화로 설명하였다. 스펙트럼 처리와 계산 화학을 조합하였을 때 간단한 계에서 측정한 겹쳐진 스펙트럼 결과는 해석할 수 있었지만, 자연과 같은 복잡계에서 측정한 겹쳐진 스펙트럼을 해석하는 것은 여전히 불가능한 상황이다. 그러나 향후 분석 및 신호 처리 기술 발달에 따라 복잡계뿐만 아니라 자연계에서 일어나는 계면 반응을 해석할 수 있을 것으로 기대한다.

• Nuclear Engineering and Technology
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• 제55권3호
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• pp.902-907
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• 2023

To understand the eutectic reaction mechanism and the relocation behavior of the core debris is indispensable for the safety assessment of core disruptive accidents (CDAs) in sodium-cooled fast reactors (SFRs). This paper addresses reaction products and their distribution of the eutectic melting/solidifying reaction of boron carbide (B₄C) and stainless-steel (SS). The influence of the existence of carbon on the B₄C-SS eutectic reaction was investigated by comparing the iron boride (FeB)-SS reaction by Raman spectroscopy with Multivariate Curve Resolution (MCR) analysis. The scanning electron microscopy with dispersive X-ray spectrometer was also used to investigate the elemental information of the pure metals such as Cr, Ni, and Fe. In the B₄C-SS samples, a new layer was formed between B₄C/SS interface, and the layer was confirmed that the formed layer corresponded to amorphous carbon (graphite) or FeB or Fe₂B. In contrast, a new layer was not clearly formed between FeB and SS interface in the FeB-SS samples. All samples observed the Cr-rich domain and Fe and Ni-rich domain after the reaction. These domains might be formed during the solidifying process.

• Asian Pacific Journal of Cancer Prevention
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• 제14권11호
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• pp.6293-6299
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• 2013

Background: A number of clinicopathologic factors have been found to be associated with pathological lymph node metastasis (pLNM) in rectal cancer; however, most of them can only be identified by expensive high resolution imaging or obtained after surgical treatment. Just like the Child-Turcotte-Pugh (CTP) and the model for end-stage liver disease (MELD) scores which have been widely used in clinical practice, our study was designed to assess the pre-operative factors which could be obtained easily to predict intra-operative pLNM in rectal cancer. Methods: A cohort of 469 patients who were treated at our hospital in the period from January 2003 to June 2011, and with a pathologically hospital discharge diagnosis of rectal cancer, were included. Clinical, laboratory and pathologic parameters were analyzed. A multivariate unconditional logistic regression model, areas under the curve (AUC), the Kaplan-Meier method (log-rank test) and the Cox regression model were used. Results: Of the 469 patients, 231 were diagnosed with pLNM (49.3%). Four variables were associated with pLNM by multivariate logistic analysis, age<60 yr (OR=1.819; 95% CI, 1.231-2.687; P=0.003), presence of abdominal pain or discomfort (OR=1.637; 95% CI, 1.052-2.547; P=0.029), absence of allergic history (OR=1.879; 95% CI, 1.041-3.392; P=0.036), and direct $bilirubin{\geq}2.60{\mu}mol/L$ (OR=1.540; 95% CI, 1.054-2.250; P=0.026). The combination of all 4 variables had the highest sensitivity (98.7%) for diagnostic performance. In addition, age<60 yr and direct $bilirubin{\geq}2.60{\mu}mol/L$ were found to be associated with prognosis. Conclusion: Age, abdominal pain or discomfort, allergic history and direct bilirubin were associated with pLNM, which may be helpful for preoperative selection.