195,525 research outputs found
Lee Ha Min
No full text학위논문(석사)--아주대학교 일반대학원 :에너지시스템학과,2014. 2CCS 기술은 발전소 등에서 발생되는 CO2를 대기 중에 배출하는 대신 이를 포집하여 지하 심부에 격리하는 기술로서 CO2 배출량의 약 80∼90%가 포집 될 수 있는 것으로 알려져 있다. CCS 기술 중에서 CO2를 저장하는 기술로는 해양 저장(Ocean storage), 광물탄산염화(Mineral carbonation) 및 지중저장(Geological storage) 등이 있다. 이 중 지중저장 기술은 지하 심부의 지질층에 CO2를 효율적으로 주입하기 위한 기술로서 이 때 저장되는 CO2의 성상은 온도 및 압력 조건이 각각 31.1℃, 7.38 MPa인 상태에서 이루어지는 초임계상태(supercritical phase)이다. 초임계상태란 액체와 기체의 구별이 없어지는 상(phase)으로 액체와 같은 밀도에 기체와 같은 점성을 지니기 때문에 저장효율 증대를 위해 가장 적합한 상태이다. 이러한 조건은 통상의 지온경사와 정수압 등을 고려했을 때 지하 800m 이하의 심부 지층에서 자연적으로 얻어질 수 있으므로 지중저장은 주로 이 깊이 이하의 지질구조를 대상으로 이루어진다.
지중저장을 위한 연구는 국외의 경우 다양하게 진행되고 있으나, 국내의 경우 대부분 모델링 연구에 집중되고 있으며 국외의 경우와 비교해 보았을 때 지중저장 특성화를 위한 실내실험을 통한 기초 연구는 매우 부족한 실정이다. 그러므로 본 연구에서는 실제 CO2 주입환경과 유사한 실험실 규모의 초임계 환경을 모사하는 기술을 고안하고, 각각의 다른 염도 조건 즉, 심부 대염수층의 주입 조건에서 CO2 주입 전후 일어나는 압력 변화와 그때 포획된 CO2의 양 등을 측정하여 대염수층의 염도와 초임계 CO2와 코어(암석)간의 반응성에 관한 실험을 진행하였다. 대염수층의 염수농도는 NaCl과 CaCl2를 사용하여 각각 5, 10, 15, 25 wt%로 변화를 주었고, CO2 주입 온도와 압력은 지중저장조건인 50℃, 150bar로 고정하여 실험을 실시하였다. 반응시간에 따른 포획반응을 관찰하기위해 15일과 60일로 나누어 실험을 진행하였으며 광물화 반응 여부는 XRF, XRD 분석을 통해 확인하였고, Aspen Plus를 통해 포획된 CO2의 양을 계산하였다.제 1 장 서론
제 1 절 연구 배경 및 목적
제 2 절 심부 대염수층 지중저장기술의 연구동향
제 2 장 CO2 지중저장의 이론적 배경
제 1 절 초임계 CO2의 성질
제 2 절 지중 격리 메커니즘
제 3 절 공극률(porosity)
제 4 절 모세관압(capillary pressure)
제 3 장 CO2 지중저장반응기 장치 설계 및 제작
제 1 절 장치 구성
제 2 절 실험장비의 검증
제 4 장 CO2 지중저장 실험
제 1 절 실험 준비
제 2 절 실험 방법
제 3 절 반응시간 결정을 위한 CO2-코어 반응 실험 결과
제 5 장 CO2 지중저장 실험 결과
제 1 절 공극률 측정 실험 결과
제 2 절 Brine(NaCl/CaCl2) 조건에 따른 CO2-코어 반응 결과
제 3 절 압력변화 결과에 따른 CO2 포획량 계산
제 4 절 광물화 반응에 의한 CO2 포획 실험 결과
제 6 장 결론
참고문헌Maste
Min Lee
No full text학위논문(박사)--아주대학교 일반대학원 :전자공학과,2014. 8List of Figures
Abbreviation
1 Introduction
1.1 Background and Motivation
1.2 Contributions
2 Closed-form Ergodic Cooperative Capacity for CoMP Joint Diversity Transmission
2.1 CoMP JDTN Model and Capacities
2.2 PDF of Instantaneous DC-SNR
2.3 Closed-form ECC
2.4 Proof of Theorem 2.1
2.5 ECC Behaviors
3 Joint Power Allocation for Ergodic Cooperative Capacity Maximization
3.1 CoMP JDTN Model
3.2 Problem Formulation and Optimum Power Allocation
3.3 JPA for Co2P JDT under Unity TCPP
3.4 JPA for Co2P JDT under Non-unity TCPP
3.5 JPA for Co3P JDT
3.6 Numerical Results
4 Approximations for Ergodic Capacities in Rayleigh fading Channels
4.1 Approximations for EC of a Single-branch Rayleigh-faded Channel
4.2 Approximation for ECC of Two-branch Rayleigh-faded Channels at the Balanced Point
4.3 Approximation for ECC of Three-branch Rayleigh-faded Channels at the Balanced Point
5 Joint Power Allocation for Total Coordination Point Power Minimization
5.1 Problem Formulation and Optimum Power Allocation
5.2 Approximated Expressions of JPA for Co2P JDT
5.3 JPA for Co2P JDT using Duality Condition
5.4 JPA for Co3P JDT using Duality Condition
5.5 Numerical Results
6 Conclusions
ReferencesDoctoralIn this dissertation, we study a coordinated multi-point (CoMP) joint diversity transmission network (JDTN) in Rayleigh fading channels.
First, as a useful tool to analyze the performance of the CoMP JDTN, we derive a closed-form ergodic cooperative capacity (ECC) expression of the CoMP JDTN in Rayleigh fading channels. To obtain the closed-form ECC expression, we first derive a closed-form probability density function (PDF) of the instantaneous diversity-combined signal-to-noise ratio, and then a closed-form ECC expression for the CoMP JDTN by using the derived closed-form PDF.
Second, using the closed-form ECC expression, we deal with the joint power allocation (JPA) problem for the CoMP JDTN with the constraint on the total coordination point power (TCPP), aimed at maximizing the ECC in Rayleigh fading channels. We first consider the coordinated two-point (Co2P) JDTN that consists of two coordinated transmission points (CTPs) - CTP1 and CTP2 - and a user equipment, under the unity TCPP. We obtain the relationship that yields the optimum CTP1 power with respect to the mean branch gain-to-noise ratios (GNRs). Then, we introduce two simple log-linear approximated (LLA) expressions for the optimum CTP1 power, with exact slope and approximated slope, respectively, at the balanced point. Using the LLA expressions, we also draw efficient criteria for turning off Co2P joint diversity transmission (JDT). Next, we extend the JPA problem to the case of a non-unity TCPP constraint. We furthermore introduce more accurate log-quadratic approximated (LQA) expressions for obtaining the CTP powers. Then, we extend our study to a coordinated three-point (Co3P) JDTN. Given the mean branch GNRs, we obtain a LLA expression for obtaining the optimum power of the third CTP (i.e., the worst quality-providing CTP). After obtaining the third-CTP power, we obtain the CTP powers of the two better quality-providing CTPs by invoking the LLA CTP power expressions for Co2P JDT power allocation, under the remaining power that is given by the TCPP minus the third-CTP power.
Finally, we deal with the JPA problem for the CoMP JDTN with an ergodic rate requirement in Rayleigh fading channels, aimed at minimizing the TCPP. Prior to the JPA problem for minimizing the TCPP in the CoMP JDTN, we present several approximate expressions for the EC of a single-branch Rayleigh-faded channel and the ECC of cooperative-branch Rayleigh-faded channels. Next, for the Co2P JDTN, we derive an optimality-conserving condition for the optimum CTP powers. We present two simple expressions such as a LLA expression for optimum CTP1 power and a LQA expression for optimum CTP2 power. Then, we present an improved JPA method for the Co2P JDTN, which can maintain the TCPP at an almost optimum level for the ergodic rate requirement. In this improved method, we obtain a much better TCPP approximation to give the required ergodic rate by using the linear interpolation of two known nearby sets of TCPP versus the ergodic rate. Using the TCPP approximation, we then obtain two CTP powers by using the LQA and LLA CTP power expressions of Co2P JDT for ECC maximization under the TCPP constraint. We further extend this method to the Co3P JDTN according to the similar process to that in the Co2P JDTN
Min-Jeong Lee
No full text학위논문(석사)--아주대학교 일반대학원 :의학과,2014. 8“신대체요법을 언제 시작해야 하는가?”란 물음에 답하는 것은 어려운 일이다. 신대체요법이 임박한 말기신장질환 환자에서 언제 투석을 시작할지에 대한 결정을 돕기 위하여, 본 연구에서는 한국 3차 의료기관에서 혈액투석 시작 시점에서의 말기신장질환 환자의 임상적 특징을 분석하고자 한다. 2010년 1월부터 2012년 12월까지 처음 혈액투석을 시작한 409명의 환자를 후향적으로 분석하였다. 말기신부전의 가장 흔한 원인은 당뇨병성신증 (48.7%) 였으며, 두 번째로 흔한 원인은 조직검사로 증명된 사구체신염 (11.7%)이었다. 혈액투석 시작 시점에서의 사구체 여과율은 5.59 ~ 7.82 ml/min/1.73m2 였다 (Nankivell equation 으로 계산한 사구체 여과율 제외). 이러한 사구체 여과율은 사구체 여과율 계산 공식을 어떤 것을 사용하는가에 따라 통계학적으로 유의한 차이가 있었다 (p ≤ 0.002). 다섯 가지의 사구체 여과율 공식 중에서, Modified Cockcroft-Gault 식, MDRD 식과 CKD-EPI 식이 만성신부전 합병증과 유의한 상관관계를 보였다. 특히 Modified Cockcroft-Gault 식의 경우 변동 계수(CV; coefficient of variation)가 가장 작았으며, 이는 이 식이 본 연구의 환자들의 eGFR 값을 가장 재현성 있게 나타낸다는 것을 의미한다. 혈액투석을 시작하게 된 주된 이유는 부종 (38.4%), 요독 증세 (35.0%) 였다. 당뇨 환자는 비당뇨 환자에 비하여 더 나이가 많고, 투석 시작시 높은 사구체 여과율을 보였다. 59.2% 의 환자는 외래를 경유하여 혈액투석을 시작하였고, 40.8% 의 환자는 응급실로 내원하여 혈액투석을 시작하였다. 응급실로 내원하여 투석을 시작한 경우, 고칼륨혈증 및 대사성 산증이 외래 내원하여 시작한 환자군에 비하여 더 심한 소견을 보였다. 현재 한국에서 행해지고 있는 혈액 투석 시작 시점에서의 말기신장질환 환자들의 임상적 특징 및 혈액검사 자료 등의 자료가 향후 투석 시작 시점을 결정하는데 유용한 정보가 되길 기대한다.ABSTRACTS
LIST OF FIGURES
LIST OF TABLES
I. INTRODUCTION
II. METHODS
A. Patient selection
B. Laboratory data
C. Estimated glomerular filtration rate
D. Statistical analysis
III. RESULTS
IV. DISCUSSION
REFERENCES
FIGURES
TABLES
국문요약Maste
Multiply imputing missing values in data sets with mixed measurement scales using a sequence of generalised linear models
No full textMultiple imputation is a commonly used approach to deal with missing values. In this approach, an imputer repeatedly imputes the missing values by taking draws from the posterior predictive distribution for the missing values conditional on the observed values, and releases these completed data sets to analysts. With each completed data set the analyst performs the analysis of interest, treating the data as if it were fully observed. These analyses are then combined with standard combining rules, allowing the analyst to make appropriate inferences which take into account the uncertainty present due to the missing data. In order to preserve the statistical properties present in the data, the imputer must use a plausible distribution to generate the imputed values. In data sets containing variables with different measurement scales, e.g. some categorical and some continuous variables, this is a challenging problem. A method is proposed to multiply impute missing values in such data sets by modelling the joint distribution of the variables in the data through a sequence of generalised linear models, and data augmentation methods are used to draw imputations from a proper posterior distribution using Markov Chain Monte Carlo (MCMC). The performance of the proposed method is illustrated using simulation studies and on a data set taken from a breast feeding study
Prionospio expansa Lee & Lee & Min 2023, sp. nov.
No full text<i>Prionospio expansa</i> sp. nov. <p>urn:lsid:zoobank.org:act: FFB09C6C-8B69-4FD3-A49B-EFCC348F3B14</p> <p>Figs 2–4</p> Diagnostic features <p>Prostomium with orangish-brown pigmentations, anteriormost body conspicuously expended (Fig. 3C– D), four pairs of short, apinnate, and cirriform branchiae, dorsal crests and ventral flaps absent.</p> Etymology <p> The specific epithet ‘ <i>expansa’</i> refers to the conspicuously expanded body in the anteriomost chaetigers of the new species.</p> Material examined <p> <b>Holotype</b> KOREA • 1 complete spec. with palps; Yellow Sea, Yeongjongdo Is., Eurwangni Beach; 37.4472 <b>°</b> N, 126.3705 <b>°</b> E; 1 Apr. 2022; Geon Hyeok Lee leg.; intertidal, silty sand; NIBRIV0000900991.</p> <p> <b>Paratypes</b> KOREA • 1 complete spec.; Yellow Sea, Jaeun Is.; 34.9200 <b>°</b> N, 126.0572 <b>°</b> E; 24 Sep. 2021; Geon Hyeok Lee leg.; low intertidal, muddy sand; NIBRIV0000900998 • 4 af; Yellow Sea, Deokjeok Is.; 37.2065 <b>°</b> N, 126.1743 <b>°</b> E; 24 Oct. 2021; Geon Hyeok Lee leg.; low intertidal, muddy sand NIBRIV0000900999 • 10 complete specs, 9 af, 10 mf, 7 pf; same collection data as for holotype; 1 Apr. 2022; Geon Hyeok Lee leg.; NIBRIV0000901890–1891 (2 complete specs), NIBRIV0000900992–0993 (2 complete specs), other for NIBRIV0000901000 • 1 complete spec.; Yellow Sea, Deokjeok Is.; 37.2165 <b>°</b> N, 126.1120 <b>°</b> E; 16 Apr. 2022; Geon Hyeok Lee leg.; low intertidal, muddy sand; NIBRIV0000901001 • 7 complete specs, 21 af, 5 mf; same collection data as for holotype; 2 May. 2022; NIBRIV0000901002 • 1 af; same collection data as for holotype; 15 Jan. 2021; GenBank COI gene OQ672519, GenBank 16S gene OQ685963, GenBank 18S gene OQ685953; NIBRIV0000900994 • 3 complete specs; same collection data as for holotype; 1 Apr. 2022; GenBank COI gene OQ672520 – 2522, GenBank 16S gene OQ685964 – 5966, GenBank 18S gene OQ685954 – 5956; NIBRIV0000900995–0997.</p> Description <p>Holotype complete with 90 chaetigers, about 0.41 mm wide at chaetiger 4 and about 14.2 mm long. Paratypes complete with 61–105 chaetigers, up to 0.51 mm wide at chaetiger 4 and about up to 15.5 mm long. Body conspicuously expanded dorsoventrally in chaetigers 2–6 (Fig. 3C–D), cylindrical afterwards, tapered towards pygidium (Fig. 4A).</p> <p>Prostomium subtriangular, with three small peaks on anterior margin (Fig. 4E), extending posteriorly to posterior end of chaetiger 1 as a distinct caruncle; two pairs of reddish and rounded to oval eyes arranged in trapezoid, anterolateral pair larger and wider apart than posterior pair (Figs 2A, 3C–D). Peristomium reduced, fused to chaetiger 1, not forming lateral wings. Palps reaching up to about chaetiger 25 with longitudinal groove lined with fine cilia. Nuchal organs U-shaped, reaching posterior end of chaetiger 1, separated by caruncle (Fig. 4C). Transverse ciliated bands and intersegmental transverse ciliation indiscernible (Fig. 4B–C).</p> <p>Chaetiger 1 moderately developed, with large, rounded notopodial postchaetal lamellae and small rounded neuropodial postchaetal lamellae; notopodial postchaetal lamellae similar in size to second notopodial postchaetal lamellae; only a few chaetae on both rami; prechaetal lamellae absent (Fig. 4B).</p> <p>Notopodial postchaetal lamellae foliaceous on chaetigers 2‒5, becoming rounded in middle chaetigers, then subtriangular in posterior chaetigers; notopodial postchaetal lamellae largest in chaetigers 3 and 4, then abruptly decreasing in size posteriorly (Fig. 4B–C). Neuropodial postchaetal lamellae foliaceous on chaetiger 2, subrectangular on chaetiger 3, rounded from chaetiger 3; neuropodial postchaetal lamellae largest in chaetigers 2 and 3, then gradually decreasing in size posteriorly. Low and rounded prechaetal lamellae in both rami present in anterior chaetigers, but absent in middle and posterior chaetigers.</p> <p>Anterior notochaetae all unilimbate capillaries, heavily granulated (Figs 2F, 3H), arranged in three rows; from about chaetiger 16, notochaetae arranged in two rows, then becoming arranged in a bundle posteriorly; anterior neurochaetae unilimbate capillaries rather thin, heavily granulated, arranged in two rows; sheaths of capillaries most broad at first 6–7 chaetigers; granulation disappeared in posterior chaetigers. Hooded hooks in notopodia appearing from chaetigers 28–38 (usually 35–38), numbering 1–2 at first, increasing up to four per fascicle; hooks in neuropodia usually appearing from chaetigers 15–17 (usually 17), numbering 1–2 at first, increasing up to six per fascicle (Fig. 5); hooks multidentate (Figs 2H, 3J, 4G), with three (Fig. 4I) or four (Fig. 4H) pairs arranged in two vertical rows and a smallest uppermost tooth above main fang; hooks in neuropodia accompanied by 1–4 thin, long non-limbate capillaries. Ventral sabre chaetae broadly unilimbate, heavily granulated with sheaths (Figs 2G, 3I), appearing from chaetiger 10.</p> <p>Dorsal branchiae short, cirriform with rounded tip, four pairs on chaetigers 2–5 (Fig. 4D), first pair sometimes longer than last three pairs (Fig. 3B); first pair usually 1.5–2 × as long as notopodial postchaetal lamellae, up to about 3 × as long as, but not extending over two segments (Figs 2B, 3B); second and third pairs similar in length or slightly longer than notopodial postchaetal lamellae, usually extending one segment, but slightly over than one segment in large specimens (Figs 2C–D, 3F); last pair distinctly usually 2 × as long as notopodial postchaetal lamellae; branchiae with heavy ciliation at inner and outer margins (Figs 2E, 3G); branchiae completely free from notopodial postchaetal lamellae.</p> <p>Dorsal crest, lateral pouches, and ventral flaps absent.</p> <p>Oocytes unknown.</p> <p>Pygidium with one elongated, thick middorsal cirrus and one pair of short, thick ventral lappets, all bearing numerous non-motile sensory cirri up to 60 μm long (Fig. 4F).</p> <p>COLORATION AND PIGMENTATION. Whitish color in live specimens with orangish brown pigmentations presented on the anterior part of prostomium, between anterolateral eyes of prostomium (Fig. 3B), and lateral paired ventral lappets of pygidium. In formalin- or ethanol-fixed specimens yellowish white color, pigmentation on prostomium usually remained (Fig. 3C–D), but pigmentation on pygidium usually fades or is completely lost.</p> Methyl green staining pattern (MGSP) <p>Twelve complete specimens were examined for MGSP. Anterior margin of prostomium, dorsal and lateral sides of peristomium, caruncle, margins of postchaetal lamellae and branchiae, pygidium weakly stained; staining almost faded out in about 2–3 hours and completely disappeared in about 2–3 days. Lateral and ventral sides of chaetigers 8–22 intensely stained, and narrow transverse bands along anterior edges of chaetigers 10–18 most intensely stained; the patterns remained for at least one week and faded out after about a month.</p> Habitat and distribution <p>Adults of this new species were found in muddy and silty sand in the intertidal zone of the Yellow Sea.</p> Genetics <p> Sequences of three gene fragments (COI, 16S rDNA, and 18S rDNA) were determined from four adult specimens of <i>Prionospio expansa</i> sp. nov. The length of obtained DNA sequences were 605 bp for COI, 532 bp for 16S rDNA, and 1,762 bp for 18S rDNA. The newly determined sequences have been registered in GenBank with the accession numbers OQ672519–22 (COI), OQ685963–6 (16S rDNA), and OQ685953–6 (18S rDNA). The intraspecific genetic distances were 0–0.2% in both COI and 16S rDNA, and no variation was detected in 18S rDNA. Based on available gene data of <i>Prionospio</i> species from GenBank, the new species is genetically closest to <i>P. japonica</i> from Northeast Asia (squares in Fig. 6). The genetic differences between sequences of the new species and those of <i>P. japonica</i> from Japan and Korea were 20.7% (97/469 bp, MW054868) in COI, 10.4% (59/469 bp, LC595695) in 16S rDNA, and 0.1% (1/1,619 bp, LC545865) in 18S rDNA.</p>Published as part of <i>Lee, Geon Hyeok, Lee, Ha-Eun & Min, Gi-Sik, 2023, Morphology and phylogeny of a new polychaete, Prionospio expansa (Annelida: Spionidae) from the intertidal zone of the Yellow Sea, Korea, pp. 86-98 in European Journal of Taxonomy 885</i> on pages 89-94, DOI: 10.5852/ejt.2023.885.2191, <a href="http://zenodo.org/record/8205484">http://zenodo.org/record/8205484</a>
Multiple imputation for missing data and statistical disclosure control for mixed-mode data using a sequence of generalised linear models
No full textMultiple imputation is a commonly used approach to deal with missing data and to protect confidentiality of public use data sets. The basic idea is to replace the missing values or sensitive values with multiple imputation, and we then release the multiply imputed data sets to the public. Users can analyze the multiply imputed data sets and obtain valid inferences by using simple combining rules, which take the uncertainty due to the presence of missing values and synthetic values into account. It is crucial that imputations are drawn from the posterior predictive distribution to preserve relationships present in the data and allow valid conclusions to be made from any analysis. In data sets with different types of variables, e.g. some categorical and some continuous variables, multivariate imputation by chained equations (MICE) (Van Buuren (2011)) is a commonly used multiple imputation method. However, imputations from such an approach are not necessarily drawn from a proper posterior predictive distribution. We propose a method, called factored regression model (FRM) to multiply impute missing values in such data sets by modelling the joint distribution of the variables in the data through a sequence of generalised linear models.We use data augmentation methods to connect the categorical and continuous variables and this allows us to draw imputations from a proper posterior distribution. We compare the performance of our method with MICE using simulation studies and on a breastfeeding data. We also extend our modelling strategies to incorporate different informative priors for the FRM to explore robust regression modelling and the sparse relationships between the predictors. We then apply our model to protect confidentiality of the current population survey (CPS) data by generating multiply imputed, partially synthetic data sets. These data sets comprise a mix of original data and the synthetic data where values chosen for synthesis are based on an approach that considers unique and sensitive units in the survey. Valid inference can then be made using the combining rules described by Reiter (2003). An extension to the modelling strategy is also introduced to deal with the presence of spikes at zero in some of the continuous variables in the CPS data
CREAM-based communication error analysis method (CEAM) for nuclear power plant operators’ communication
No full textCommunication error has been considered a primary cause of many incidents and accidents in the nuclear industry. In order to prevent these accidents, a method for the analysis of such communication errors is proposed here. This paper presents a qualitative and a quantitative method to analyze communication errors. The qualitative method focuses on finding a root cause of the communication error and predicting the type of communication error which could happen in nuclear power plants. We develop context conditions and antecedent-consequent links of influential factors related to communication errors. The quantitative analysis method focuses on estimating the probability of communication errors. To accomplish the quantification of communication errors, the Cognitive Speaking Process (CSP) is defined and a method to estimate the weighting factors and the probability is suggested. Finally, case studies conducted to validate the applicability of the proposed methods are detailed. From the results, we can foresee the effects of given plant conditions on communication errors and reduce the error occurrences. (C) 2010 Published by Elsevier Ltd
An Investigation of Human Communication Errors and Causes in Nuclear Power Plants (NPPs)
No full textDetection of large pK(alpha) perturbations of an inhibitor and a catalytic group at an enzyme active site, a mechanistic basis for catalytic power of many enzymes
No full textDelta (5)-3-Ketosteroid isomerase catalyzes cleavage and formation of a C-H bond at a diffusion-controlled limit. By determining the crystal structures of the enzyme in complex with each of three different inhibitors and by nuclear magnetic resonance (NMR) spectroscopic investigation, we evidenced the ionization of a hydroxyl group (pK(a) similar to 16.5) of an inhibitor, which forms a low barrier hydrogen bond (LBHB) with a catalytic residue Tyr(14) (pK(a) similar to 11.5), and the protonation of the catalytic residue Asp(38) With pK(a) of similar to4.5 at pH 6.7 in the interaction with a carboxylate group of an inhibitor. The perturbation of the pK(a) values in both cases arises from the formation of favorable interactions between inhibitors and catalytic residues. The results indicate that the pK(a) difference between catalytic residue and substrate can be significantly:reduced in the active site environment as:a result of the formation of energetically favorable interactions during the course of enzyme reactions. The reduction in the pK(a) difference should facilitate the abstraction of a proton and thereby eliminate a large fraction of activation energy in general acid/base enzyme reactions. The pK(a) perturbation provides a mechanistic ground for the fast reactivity of many enzymes and for the understanding of how some enzymes are able to extract a proton from a C-H group with a pK(a) value as high as similar to 30
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