Temperature- and quantum phonon effects on Holstein-Hubbard bipolarons

The one-dimensional Holstein-Hubbard model with two electrons of opposite spin is studied using an extension of a recently developed quantum Monte Carlo method, and a very simple yet rewarding variational approach, both based on a canonically transformed Hamiltonian. The quantum Monte Carlo method yields very accurate results in the regime of small but finite phonon frequencies, characteristic of many strongly correlated materials such as, e.g., the cuprates and the manganites. The influence of electron-electron repulsion, phonon frequency and temperature on the bipolaron state is investigated. Thermal dissociation of the intersite bipolaron is observed at high temperatures, and its relation to an existing theory of the manganites is discussed.Comment: 12 pages, 7 figures; final version, accepted for publication in Phys. Rev.

Fractional calculus and the ESR test

We consider the partial di_x005F_x005F_x005F_x000B_erential equation of a mathematical model proposed by Sharma et al. [1] to describe the concentration of nutrients in blood, a factor which influences erythrocyte sedimentation rate. Introducing in it a fractional derivative in the Caputo sense, we create a new, timefractional mathematical model which contains, as a particular case, the original model. We obtain an analytic solution of this time-fractional partial di_x005F_x005F_x005F_x000B_erential equation in terms of Mittag-Le_x005F_x005F_x005F_x000F_er and Wright functions and to show that our model is more realistic than the Sharma model2469270

Sensor-embedded face masks for detection of volatiles in breath: a proof of concept study

The correlation between breath volatilome and health is prompting a growing interest in the development of sensors optimized for breath analysis. On the other hand, the outbreak of COVID-19 evidenced that breath is a vehicle of infection; thus, the introduction of low-cost and disposable devices is becoming urgent for a clinical implementation of breath analysis. In this paper, a proof of concept about the functionalization of face masks is provided. Porphyrin-based sensors are among the most performant devices for breath analysis, but since porphyrins are scarcely conductive, they make use of costly and bulky mass or optical transducers. To overcome this drawback, we introduce here a hybrid material made of conducting polymer and porphyrins. The resulting material can be easily deposited on the internal surface of standard FFP face masks producing resistive sensors that retain the chemical sensitivity of porphyrins implementing their combinatorial selectivity for the identification of volatile compounds and the classification of complex samples. The sensitivity of sensors has been tested with respect to a set of seven volatile compounds representative of diverse chemical families. Sensors react to all compounds but with a different sensitivity pattern. Functionalized face masks have been tested in a proof-of-concept test aimed at identifying changes of breath due to the ingestion of beverages (coffee and wine) and solid food (banana- and mint-flavored candies). Results indicate that sensors can detect volatile compounds against the background of normal breath VOCs, suggesting the possibility to embed sensors in face masks for extensive breath analysis

Proline Enantiomers Discrimination by (L)-Prolinated Porphyrin Derivative Langmuir–Schaefer Films: Proof of Concept for Chiral Sensing Applications

A porphyrin derivative functionalized with the L-enantiomer of proline amino acid was characterized at the air–pure water interface of the Langmuir trough. The porphyrin derivative was dissolved in dichloromethane solution, spread at the air–subphase interface and investigated by acquiring the surface pressure vs. area per molecule Langmuir curves. It is worth observing that the behavior of the molecules of the porphyrin derivative floating film was substantially influenced by the presence of L-proline amino acid dissolved in the subphase (10−5 M); on the contrary, the physical chemical features of the floating molecules were only slightly influenced by the D-proline dissolved in the subphase. Such an interesting chirality-driven selection was preserved when the floating film was transferred onto solid supports by means of the Langmuir–Schaefer method, but it did not emerge when a spin-coating technique was used for the layering of the tetrapyrrolic derivatives. The obtained results represent proof of concept for the realization of active molecular layers for chiral discrimination: porphyrin derivatives, due to their intriguing spectroscopic and supramolecular properties, can be functionalized with the chiral molecule that should be detected. Moreover, the results emphasize the crucial role of the deposition technique on the features of the sensing layers

A Clinical, Epidemological, Laboratorial, Histological And Ultrasonographical Evaluation Of Anti-hcv Eia-2 Positive Blood Donors.

Between 1992 and 1997, 790 blood donors with anti-HCV EIA-2 strongly reagent (relationship between the sample optical density/cut-off > 3) detected at the blood bank serological screening, were evaluated in ambulatory environment. They were all negative for Chagas disease, syphilis, hepatitis B (HBsAg) and AIDS. Blood samples were collected at the first ambulatorial evaluation, for hemogram, biochemical tests and new serological tests for HCV (anti-HCV EIA-2). In blood samples of 226 repeatedly reagent anti-HCV EIA-2 blood donors, supplementary immunoblot test for HCV (RIBA-2) was used. In 209 donors, the presence of HCV-RNA was investigated by the PCR test. The abdominal ultrasonography was realized in 366 donors. In 269 patients liver biopsy was performed for the histopathological study. The follow-up of blood donors showed that 95.6% were repeatedly EIA-2 reagent, 94% were symptomless and denied any hepatitis history, with only 2% mentioning previous jaundice. In 47% of this population at least one risk factor has been detected for the HCV transmission, the use of intravenous drugs being the main one (27.8%). Blood transfusion was the second factor for HCV transmission (27.2%). Hepatomegaly was detected in 54% of the cases. Splenomegaly and signs of portal hypertension have seldom been found in the physical examination, indicating a low degree of hepatic compromising in HCV. Abdominal ultrasound showed alterations in 65% of the subjects, being the steatosis the most frequent (50%). In 83. 5% of the donors submitted to the liver biopsy, the histopathological exam showed the presence of chronic hepatitis, usually classified as active (89%) with mild or moderate grade in most of the cases (99.5%). The histopathological exam of the liver was normal in 1.5% of blood donors. The RIBA-2 test and the HCV-RNA investigation by PCR were positive in respectively 91.6 and 75% of the anti-HCV EIA-2 reagent donors. The HCV-RNA research was positive in 82% of the RIBA-2 positive subjects, in 37.5% of the indeterminate RIBA-2 donors and in 9% of the negative RIBA-2 donors. Chronic hepatitis has also been observed in 50% of the histopathological exams of the anti-HCV EIA-2 reagent donors which were indeterminate RIBA-2. Among 18 blood donors with minimal changes histopathological exam 11 (61%) were HCV-RNA positive. Our blood donors anti-HCV reagent generally had clinical, laboratorial and histopathological features observed in patients with chronic HCV hepatitis and a high proportion could be identified in interviews and medical evaluation realized in blood blanks. Generally, these HCV infected donors are identified and discharged only by the serological tests results.42147-5

Proline enantiomers discrimination by (L)-prolinated porphyrin derivative Langmuir-Schaefer films: proof of concept for chiral sensing applications

A porphyrin derivative functionalized with the L-enantiomer of proline amino acid was characterized at the air-pure water interface of the Langmuir trough. The porphyrin derivative was dissolved in dichloromethane solution, spread at the air-subphase interface and investigated by acquiring the surface pressure vs. area per molecule Langmuir curves. It is worth observing that the behavior of the molecules of the porphyrin derivative floating film was substantially influenced by the presence of L-proline amino acid dissolved in the subphase (10(-5) M); on the contrary, the physical chemical features of the floating molecules were only slightly influenced by the D-proline dissolved in the subphase. Such an interesting chirality-driven selection was preserved when the floating film was transferred onto solid supports by means of the Langmuir-Schaefer method, but it did not emerge when a spin-coating technique was used for the layering of the tetrapyrrolic derivatives. The obtained results represent proof of concept for the realization of active molecular layers for chiral discrimination: porphyrin derivatives, due to their intriguing spectroscopic and supramolecular properties, can be functionalized with the chiral molecule that should be detected. Moreover, the results emphasize the crucial role of the deposition technique on the features of the sensing layers

Avaliação clínica, epidemiológica, laboratorial, histológica e ultrassonográfica de doadores de sangue anti-HCV EIA-2 positivos

Between 1992 and 1997, 790 blood donors with anti-HCV EIA-2 strongly reagent (relationship between the sample optical density/cut-off >; 3) detected at the blood bank serological screening, were evaluated in ambulatory environment. They were all negative for Chagas disease, syphilis, hepatitis B (HBsAg) and AIDS. Blood samples were collected at the first ambulatorial evaluation, for hemogram, biochemical tests and new serological tests for HCV (anti-HCV EIA-2). In blood samples of 226 repeatedly reagent anti-HCV EIA-2 blood donors, supplementary "immunoblot" test for HCV (RIBA-2) was used. In 209 donors, the presence of HCV-RNA was investigated by the PCR test. The abdominal ultrasonography was realized in 366 donors. In 269 patients liver biopsy was performed for the histopathological study. The follow-up of blood donors showed that 95.6% were repeatedly EIA-2 reagent, 94% were symptomless and denied any hepatitis history, with only 2% mentioning previous jaundice. In 47% of this population at least one risk factor has been detected for the HCV transmission, the use of intravenous drugs being the main one (27.8%). Blood transfusion was the second factor for HCV transmission (27.2%). Hepatomegaly was detected in 54% of the cases. Splenomegaly and signs of portal hypertension have seldom been found in the physical examination, indicating a low degree of hepatic compromising in HCV. Abdominal ultrasound showed alterations in 65% of the subjects, being the steatosis the most frequent (50%). In 83.5% of the donors submitted to the liver biopsy, the histopathological exam showed the presence of chronic hepatitis, usually classified as active (89%) with mild or moderate grade in most of the cases (99.5%). The histopathological exam of the liver was normal in 1.5% of blood donors. The RIBA-2 test and the HCV-RNA investigation by PCR were positive in respectively 91.6 and 75% of the anti-HCV EIA-2 reagent donors. The HCV-RNA research was positive in 82% of the RIBA-2 positive subjects, in 37.5% of the indeterminate RIBA-2 donors and in 9% of the negative RIBA-2 donors. Chronic hepatitis has also been observed in 50% of the histopathological exams of the anti-HCV EIA-2 reagent donors which were indeterminate RIBA-2. Among 18 blood donors with minimal changes histopathological exam 11 (61%) were HCV-RNA positive. Our blood donors anti-HCV reagent generally had clinical, laboratorial and histopathological features observed in patients with chronic HCV hepatitis and a high proportion could be identified in interviews and medical evaluation realized in blood blanks. Generally, these HCV infected donors are identified and discharged only by the serological tests results.Entre 1992 e 1997 foram avaliados, ambulatorialmente, 790 doadores de sangue com teste anti-HCV EIA-2 fortemente reagente (relação entre a densidade ótica da amostra / "cut-off" >; 3), que haviam sido detectados na triagem sorológica do banco de sangue. Todos eram negativos para doença de Chagas, sífilis, hepatite B (HBsAg) e AIDS. Amostras de sangue foram coletadas, na primeira consulta ambulatorial, para a realização de hemograma, exames bioquímicos e novos testes sorológicos para a HVC (anti-HCV EIA-2). Em 226 doadores anti-HCV EIA-2 repetidamente reagentes, realizou-se o teste suplementar de "immunoblot" para a HVC (RIBA-2). Em 209 doadores, pesquisou-se a presença do RNA do VHC pelo teste do PCR, através de exame automatizado (HCV-AMPLICOR, ROCHE). A ultra-sonografia abdominal foi realizada em 366 doadores e a biópsia hepática em 269 concordantes. Notou-se que 95,6% eram EIA-2 repetidamente reagentes, 94% eram assintomáticos e que apenas 2% referiram icterícia pregressa. Em 47% detectou-se, pelo menos, um fator de risco para a transmissão do VHC, sendo o uso de drogas E.V. o principal deles (27,8%). A transfusão de sangue foi o segundo fator na transmissão da HVC (27,2%). Hepatomegalia foi encontrada em 54%. Esplenomegalia e sinais de hipertensão portal foram raramente encontrados no exame físico, denotando o baixo grau de comprometimento hepático na HVC. A ultra-sonografia abdominal mostrou-se alterada em 65% dos indivíduos, sendo a esteatose a alteração mais freqüentemente observada (50%). Em 83,5% dos doadores submetidos à biópsia hepática, diagnosticou-se hepatite crônica, geralmente classificada como ativa (89%) e de grau leve ou moderado na maioria dos casos (99,5%). O histopatológico foi normal em 1,5% dos doadores. O teste de RIBA-2 e a pesquisa do RNA do VHC pelo PCR foram positivos em, respectivamente, 91,6 e 75% dos doadores anti-HCV EIA-2 reagentes. A pesquisa do RNA do VHC foi positiva em 82% dos indivíduos RIBA-2 reagentes, em 37,5% dos doadores RIBA-2 indeterminados e em 9% dos RIBA-2 negativos. Hepatite crônica foi observada em 50% dos doadores RIBA-2 indeterminados. Entre 18 doadores com alterações mínimas, ao exame histopatológico, 11 (61%) eram positivos para o RNA do VHC. Nossos doadores de sangue anti-HCV reagentes geralmente apresentam alterações clínicas, laboratoriais e histopatológicas próprias de pacientes com hepatites crônicas pelo VHC e uma elevada proporção destes podem ser identificados em entrevistas e avaliação médicas rotineiramente realizadas em bancos de sangue. Geralmente estes doadores infectados pelo VHC somente são identificados e bloqueados pelos resultados dos testes sorológicos

Numerical study of the E⊗eE\otimes e Jahn-Teller polaron and bipolaron

The properties of the polaron and bipolaron are explored in the 1D Jahn-Teller model with dynamical quantum phonons. The ground-state properties of the polaron and bipolaron are computed using a recently developed variational method. Dynamical properties of the ground state of a polaron are investigated by calculating the optical conductivity $\sigma(\omega)$. Our numerical results suggest that the Jahn-Teller and Holstein polarons are similar. However, in the strong-coupling regime qualitative differences in $\sigma(\omega)$ between the two models are found and discussed. The influence of the electron-phonon coupling and the electrostatic repulsion on the bipolaron binding energy, bipolaron masses, and correlation functions is investigated.Comment: 9 pages including 11 figures. To appear in PR

Does Tumor Extent on Needle Prostatic Biopsies Influence the Value of Perineural Invasion to Predict Pathologic Stage > T2 in Radical Prostatectomies?

Purpose: Perineural invasion (PNI) on needle prostatic biopsies (NPB) has been controversial as a marker of extraprostatic extension and consequently for planning of nerve-sparing radical prostatectomy (RP). The aim of this study was to find whether tumor extent on NPB influences the value of PNI to predict stage > pT2 on RP. Materials and Methods: This retrospective study was based on 264 consecutive patients submitted to radical retropubic prostatectomy. Their NPB were matched with whole-mount processed and totally embedded surgical specimens. Tumor extent on NPB was evaluated as the percentage of linear tissue in mm containing carcinoma in all cores. Considering the median value, patients were stratified into 2 groups: harboring less or more extensive tumors on NPB. Univariate and multivariate logistic regression analyses were used to relate stage > pT2 to PNI and other clinical and pathological variables. Results: In patients with more extensive tumors, PNI was predictive of stage > pT2 in univariate analysis but not in multivariate analysis. In less extensive tumors, PNI showed no association between any clinical or pathological variables studied; no difference in the time to biochemical progression-free status compared to patients without PNI; and, no predictive value for pathological stage > pT2 on both univariate and multivariate analyses. Conclusion: Tumor extent on NPB influences the predictive value of PNI for pathologic stage > pT2 on RP. With a higher number of small tumors currently detected, there is no evidence that perineural invasion should influence the decision on preservation of the nerve during radical prostatectomy.36443944