Exchange and Correlation in Open Systems of Fluctuating Electron Number

While the exact total energy of a separated open system varies linearly as a function of average electron number between adjacent integers, the energy predicted by semi-local density functional approximations curves upward and the exact-exchange-only or Hartree-Fock energy downward. As a result, semi-local density functionals fail for separated open systems of fluctuating electron number, as in stretched molecular ions A$_2^{+}$ and in solid transition metal oxides. We develop an exact-exchange theory and an exchange-hole sum rule that explain these failures and we propose a way to correct them via a local hybrid functional.Comment: 4 pages, 2 figure

Постгоспитальные сердечно-сосудистые осложнения у больных, перенесших некардиохирургические операции

The objective: to analyze the incidence and spectrum of cardiovascular complications within 12 months after noncardiac surgery, as well as to assess the association of preoperative values of various cardiac risk indices (CRI) and other potential risk factors with the actual development of complications.Subjects and Methods. We analyzed data of medical records and telephone interviews of 141 patients aged 65 [60-71] years who had undergone non-cardiac surgery a year before the interview The operations were low risk in 13.5% of observations, medium risk in 64.5%, and high risk in 22%. A retrospective calculation of the Revised CRI (RCRI), Individual CRI (Khoronenko CRI), and the American College of Surgeons Perioperative Risk for Myocardial Infarction or Cardiac Arrest (MICA) was performed.Results. Cardiac events (myocardial infarction, decompensation of chronic heart failure, new arrhythmias, stroke, and/or the need to prescribe or escalate the dose of cardiovascular drugs and/or hospitalization for cardiac indications, and/or death from cardiovascular diseases) within 12 months after elective noncardiac surgeries were detected in 27.7% of cases, and in 2.1% of patient's death occurred due to cardiac disorders. Predictors of cardiac events were concomitant ischemic heart disease (OR = 2.777; 95% CI 1.286-5.966; p = 0.0093) and chronic heart failure (OR = 2.900; 95% CI 1.224-6.869; p = 0, 0155), RCRI (OR = 1.886; 95% CI 1.2-8-2.944; p = 0.005), Khoronenko CRI (OR = 3254.3; 95% CI 64.33-164,638; p = 0.0001), MICA (OR = 1.628; 95% CI 1.156-2.292; p = 0.005), creatininemia on the first postoperative day (OR = 1.023; 95% CI 1.010-1.061; p = 0.005), and propensity for bradycardia during surgery (OR = 0.945; 95% CI 0.908-0.983; p = 0.005). Combined analysis of Khoronenko's CRI and postoperative creatininemia provided a very good model: area under the ROC-curve - 0.823 (95% CI 0.728-0.641; p = 0.0002).Conclusion. All studied CRIs can be used to predict posthospital cardiac events; however, the most promising is a joint assessment of Khoronenko's CRI and postoperative creatinemia.Цель исследования: проанализировать частоту и спектр сердечно-сосудистых осложнений в течение 12 мес. после перенесенных некардинальных операций, а также оценить ассоциированность предоперационных значений различных индексов кардиального риска (ИКР) и других потенциальных факторов риска с реальным развитием осложнений.Материал и методы. Проанализировали данные медицинских карт и телефонного опроса 141 больного в возрасте 65 [60-71] лет, которым за год до опроса выполнены некардиохирургические оперативные вмешательства. В 13,5% наблюдений операции имели низкий риск, в 64,5% - средний и в 22% - высокий. Выполнили ретроспективный расчет пересмотренного ИКР (ИКР Lee), индивидуального ИКР (ИКР Хороненко) и ИКР Американского колледжа хирургов (ИКР MICA).Результаты. Кардиальные события (инфаркт миокарда, декомпенсация хронической сердечной недостаточности, вновь возникшие аритмии, инсульт, и/или потребность в назначении или усилении дозировок сердечно-сосудистых лекарственных средств, и/или госпитализация вm стационар по кардиальным показаниям, и/или смерть от сердечно-сосудистых заболеваний) в течение 12 мес. после плановых некардиальных операций выявлены в 27,7% наблюдений, причем у 2,1% больных наступила смерть вследствие кардиальных причин. Предикторами кардиальных событий явились сопутствующие ишемическая болезнь сердца (ОШ = 2,777; 95%-ный ДИ 1,286-5,966; p = 0,0093) и хрони­ческая сердечная недостаточность (ОШ = 2,900; 95%-ный ДИ 1,224-6,869; p = 0,0155), ИКР Lee (ОШ = 1,886; 95%-ный ДИ 1,280-2,944; p = 0,005), ИКР Хороненко (ОШ = 3 254,3; 95%-ный ДИ 64,33-164,638; p = 0,0001), ИКР MICA (ОШ = 1,628; 95%-ный ДИ 1,156-2,292; p = 0,005), креатининемия в первые послеоперационные сутки (ОШ = 1,023; 95%-ный ДИ 1,010-1,061; p = 0,005) и склонность к брадикардии во время операций (ОШ = 0,945; 95%-ный ДИ 0,908-0,983; p = 0,005). Совместный анализ ИКР Хороненко и послеоперационной креатининемии обеспечивала модель очень хорошего качества: площадь под ROC-кривой 0,823 (95%-ный ДИ 0,728-0,641; p = 0,0002).Заключение. Для прогнозирования постгоспитальных кардиальных событий могут использоваться все изученные ИКР, однако наиболее перспективной представляется совместная оценка ИКР Хороненко и послеоперационной креатининемии

Isolation, characterization and molecular cloning of Duplex-Specific Nuclease from the hepatopancreas of the Kamchatka crab

<p>Abstract</p> <p>Background</p> <p>Nucleases, which are key components of biologically diverse processes such as DNA replication, repair and recombination, antiviral defense, apoptosis and digestion, have revolutionized the field of molecular biology. Indeed many standard molecular strategies, including molecular cloning, studies of DNA-protein interactions, and analysis of nucleic acid structures, would be virtually impossible without these versatile enzymes. The discovery of nucleases with unique properties has often served as the basis for the development of modern molecular biology methods. Thus, the search for novel nucleases with potentially exploitable functions remains an important scientific undertaking.</p> <p>Results</p> <p>Using degenerative primers and the rapid amplification of cDNA ends (RACE) procedure, we cloned the Duplex-Specific Nuclease (DSN) gene from the hepatopancreas of the Kamchatka crab and determined its full primary structure. We also developed an effective method for purifying functional DSN from the crab hepatopancreas. The isolated enzyme was highly thermostable, exhibited a broad pH optimum (5.5 – 7.5) and required divalent cations for activity, with manganese and cobalt being especially effective. The enzyme was highly specific, cleaving double-stranded DNA or DNA in DNA-RNA hybrids, but not single-stranded DNA or single- or double-stranded RNA. Moreover, only DNA duplexes containing at least 9 base pairs were effectively cleaved by DSN; shorter DNA duplexes were left intact.</p> <p>Conclusion</p> <p>We describe a new DSN from Kamchatka crab hepatopancreas, determining its primary structure and developing a preparative method for its purification. We found that DSN had unique substrate specificity, cleaving only DNA duplexes longer than 8 base pairs, or DNA in DNA-RNA hybrids. Interestingly, the DSN primary structure is homologous to well-known Serratia-like non-specific nucleases structures, but the properties of DSN are distinct. The unique substrate specificity of DSN should prove valuable in certain molecular biology applications.</p

Step-Wise Computational Synthesis of Fullerene C60 derivatives. 1.Fluorinated Fullerenes C60F2k

The reactions of fullerene C60 with atomic fluorine have been studied by unrestricted broken spin-symmetry Hartree-Fock (UBS HF) approach implemented in semiempirical codes based on AM1 technique. The calculations were focused on a sequential addition of fluorine atom to the fullerene cage following indication of the cage atom highest chemical susceptibility that is calculated at each step. The effectively-non-paired-electron concept of the fullerene atoms chemical susceptibility lays the foundation of the suggested computational synthesis. The obtained results are analyzed from energetic, symmetry, and the composition abundance viewpoints. A good fitting of the data to experimental findings proves a creative role of the suggested synthesis methodology.Comment: 33 pages, 11 figures, 2 tables, 2 chart

Entanglement Measures for Single- and Multi-Reference Correlation Effects

Electron correlation effects are essential for an accurate ab initio description of molecules. A quantitative a priori knowledge of the single- or multi-reference nature of electronic structures as well as of the dominant contributions to the correlation energy can facilitate the decision regarding the optimum quantum chemical method of choice. We propose concepts from quantum information theory as orbital entanglement measures that allow us to evaluate the single- and multi-reference character of any molecular structure in a given orbital basis set. By studying these measures we can detect possible artifacts of small active spaces.Comment: 14 pages, 4 figure

Continuous symmetry of C60 fullerene and its derivatives

Conventionally, the Ih symmetry of fullerene C60 is accepted which is supported by numerous calculations. However, this conclusion results from the consideration of the molecule electron system, of its odd electrons in particular, in a close-shell approximation without taking the electron spin into account. Passing to the open-shell approximation has lead to both the energy and the symmetry lowering up to Ci. Seemingly contradicting to a high-symmetry pattern of experimental recording, particularly concerning the molecule electronic spectra, the finding is considered in the current paper from the continuous symmetry viewpoint. Exploiting both continuous symmetry measure and continuous symmetry content, was shown that formal Ci symmetry of the molecule is by 99.99% Ih. A similar continuous symmetry analysis of the fullerene monoderivatives gives a reasonable explanation of a large variety of their optical spectra patterns within the framework of the same C1 formal symmetry exhibiting a strong stability of the C60 skeleton.Comment: 11 pages. 5 figures. 6 table