Enrico Rossi - Academia.edu (original) (raw)

Papers by Enrico Rossi

International Journal of Quantum Chemistry, 2007

A common format for quantum chemistry (QC), enhancing code interoperability and communication bet... more A common format for quantum chemistry (QC), enhancing code interoperability and communication between different programs, has been designed and implemented. An XML-based format, QC-ML, is presented for representing quantities such as geometry, basis set, and so on, while an HDF5-based format is presented for the storage of large binary data files. Some preliminary applications that use the format have been implemented and are also described. This activity was carried out within the COST in Chemistry D23 project “MetaChem,” in the Working Group “A meta-laboratory for code integration in ab initio methods.” © 2007 Wiley Periodicals, Inc. Int J Quantum Chem, 2007

Solid State Communications, 2009

We review the physics of charged impurities in the vicinity of graphene. The long-range nature of... more We review the physics of charged impurities in the vicinity of graphene. The long-range nature of Coulomb impurities affects both the nature of the ground state density profile as well as graphene's transport properties. We discuss the screening of a single Coulomb impurity and the ensemble averaged density profile of graphene in the presence of many randomly distributed impurities. Finally, we discuss graphene's transport properties due to scattering off charged impurities both at low and high carrier density.

We provide a broad review of fundamental electronic properties of two-dimensional graphene with t... more We provide a broad review of fundamental electronic properties of two-dimensional graphene with the emphasis on density and temperature dependent carrier transport in doped or gated graphene structures. A salient feature of our review is a critical comparison between carrier transport in graphene and in two-dimensional semiconductor systems (e.g. heterostructures, quantum wells, inversion layers) so that the unique features of graphene electronic properties arising from its gap- less, massless, chiral Dirac spectrum are highlighted. Experiment and theory as well as quantum and semi-classical transport are discussed in a synergistic manner in order to provide a unified and comprehensive perspective. Although the emphasis of the review is on those aspects of graphene transport where reasonable consensus exists in the literature, open questions are discussed as well. Various physical mechanisms controlling transport are described in depth including long- range charged impurity scattering, screening, short-range defect scattering, phonon scattering, many-body effects, Klein tunneling, minimum conductivity at the Dirac point, electron-hole puddle formation, p-n junctions, localization, percolation, quantum-classical crossover, midgap states, quantum Hall effects, and other phenomena.

Physical Review Letters, 2008

We calculate the carrier density dependent ground state properties of graphene in the presence of... more We calculate the carrier density dependent ground state properties of graphene in the presence of random charged impurities in the substrate taking into account disorder and interaction effects non-perturbatively on an equal footing in a self-consistent theoretical formalism. We provide detailed quantitative results on the dependence of the disorder-induced spatially inhomogeneous two-dimensional carrier density distribution on the external gate bias, the impurity density, and the impurity location. We find that the interplay between disorder and interaction is strong, particularly at lower impurity densities. We show that for the currently available typical graphene samples, inhomogeneity dominates graphene physics at low ($\lesssim 10^{12}$ cm$^{-2}$) carrier density with the density fluctuations becoming larger than the average density.

Clinical Chemistry, 2003

Background: Determining the stage of fibrosis by liver biopsy is important in managing patients w... more Background: Determining the stage of fibrosis by liver biopsy is important in managing patients with hepatitis C virus infection. We investigated the predictive value of the proprietary FibroTest score to accurately identify significant fibrosis in Australian hepatitis C patients. Methods: Serum obtained from 125 confirmed hepatitis C patients before antiviral therapy was analyzed for haptoglobin, ␣ 2 -macroglobulin, apolipoprotein A1, bilirubin, and ␥-glutamyltransferase activity, and the FibroTest score was computed. Liver fibrosis pathology was staged according to a defined system on a scale of F0 to F4. We used predictive values and a ROC curve to assess the accuracy of FibroTest scores. Results: The prevalence of significant fibrosis defined by liver biopsy was 0.38. The most useful single test for predicting significant fibrosis was serum ␣ 2 -macroglobulin (cutoff value, 2.52 g/L; sensitivity, 75%; specificity, 67%). The negative predictive value of a FibroTest score <0.1 was 85%, and the positive predictive value of a score >0.6 was 78%. Although 33 of the 125 patients had FibroTest scores <0.1 and were therefore deemed unlikely to have fibrosis, 6 (18%) had significant fibrosis. Conversely, of the 24 patients with scores >0.6 who were likely to have significant fibrosis, 5 (21%) had mild fibrosis. Of the 125 patients in the cohort, 57 (46%) could have avoided liver biopsy, but discrepant results were recorded in 11 of those 57 (19%). Conclusion: The FibroTest score could not accurately predict the presence or absence of significant liver fibrosis.

Liver International, 2004

Aim: To assess the severity of hepatic iron loading in patients with a compound heterozygous C282... more Aim: To assess the severity of hepatic iron loading in patients with a compound heterozygous C282Y/H63D HFE genotype. Methods: A total of 246 patients were referred to the Hepatology Clinic at a tertiary hospital for HFE genotyping and further assessment of elevated serum transferrin saturation and/or ferritin results, either with or without abnormal liver function tests. Subjects of the study were 19 patients compound heterozygous for HFE who had liver biopsy, quantitative liver iron estimation and liver histopathology. Results: Mild iron overload [hepatic iron concentration between 30 and 100 mmol/g dry weight], was present in 16/19 compound heterozygous patients, three patients had values within the reference range. As well as the compound heterozygous HFE genotype, 18/19 patients were found to have had at least one additional risk factor for developing either iron loading or liver disease. Conclusion: Compound heterozygous patients show no more than mild liver iron loading. The decision whether or not to recommend liver biopsy in C282Y/H63D patients with abnormal serum iron indices and/or liver function tests should be based on the need to evaluate liver damage rather than solely to assess liver iron loading.

Background: Staging hepatic fibrosis by liver biopsy guides prognosis and treatment of hepatitis ... more Background: Staging hepatic fibrosis by liver biopsy guides prognosis and treatment of hepatitis C, but is invasive and expensive. We sought to create an algorithm of serum markers that accurately and reliably predict liver fibrosis stage among hepatitis C patients. Methods: Ten biochemical markers were measured at time of liver biopsy in 117 untreated hepatitis C patients (training set). Multivariate logistic regression and ROC curve analyses were used to create a predictive model for significant fibrosis (METAVIR F2, F3, and F4), advanced fibrosis (F3 and F4), and cirrhosis (F4). The model was validated in 104 patients from other institutions. Results: A model (Hepascore) of bilirubin, ␥-glutamyltransferase, hyaluronic acid, ␣ 2 -macroglobulin, age, and sex produced areas under the ROC curves (AUCs) of 0.85, 0.96, and 0.94 for significant fibrosis, advanced fibrosis, and cirrhosis, respectively. In the training set, a score >0.5 (range, 0.0 -1.0) was 92% specific and 67% sensitive for significant fibrosis, a score <0.5 was 81% specific and 95% sensitive for advanced fibrosis, and a score <0.84 was 84% specific and 71% sensitive for cirrhosis. Among the validation set, the AUC for significant fibrosis, advanced fibrosis, and cirrhosis were 0.82, 0.90, and 0.89, respectively. A score >0.5 provided a specificity and sensitivity of 89% and 63% for significant fibrosis, whereas scores <0.5 had 74% specificity and 88% sensitivity for advanced fibrosis. Conclusions: A model of 4 serum markers plus age and sex provides clinically useful information regarding different fibrosis stages among hepatitis C patients.

New England Journal of Medicine, 1999

Hereditary hemochromatosis is associated with homozygosity for the C282Y mutation in the hemochro... more Hereditary hemochromatosis is associated with homozygosity for the C282Y mutation in the hemochromatosis (HFE) gene on chromosome 6, elevated serum transferrin saturation, and excess iron deposits throughout the body. To assess the prevalence and clinical expression of the HFE gene, we conducted a population-based study in Busselton, Australia. In 1994, we obtained blood samples for the determination of serum transferrin saturation and ferritin levels and the presence or absence of the C282Y mutation and the H63D mutation (which may contribute to increased hepatic iron levels) in 3011 unrelated white adults. We evaluated all subjects who had persistently elevated transferrin-saturation values (45 percent or higher) or were homozygous for the C282Y mutation. We recommended liver biopsy for subjects with serum ferritin levels of 300 ng per milliliter or higher. The subjects were followed for up to four years. Sixteen of the subjects (0.5 percent) were homozygous for the C282Y mutation, and 424 (14.1 percent) were heterozygous. The serum transferrin saturation was 45 percent or higher in 15 of the 16 who were homozygous; in 1 subject it was 43 percent. Four of the homozygous subjects had previously been given a diagnosis of hemochromatosis, and 12 had not. Seven of these 12 patients had elevated serum ferritin levels in 1994; 6 of the 7 had further increases in 1998, and 1 had a decrease, although the value remained elevated. The serum ferritin levels in the four other homozygous patients remained in the normal range. Eleven of the 16 homozygous subjects underwent liver biopsy; 3 had hepatic fibrosis, and 1, who had a history of excessive alcohol consumption, had cirrhosis and mild microvesicular steatosis. Eight of the 16 homozygous subjects had clinical findings that were consistent with the presence of hereditary hemochromatosis, such as hepatomegaly, skin pigmentation, and arthritis. In a population of white adults of northern European ancestry, 0.5 percent were homozygous for the C282Y mutation in the HFE gene. However, only half of those who were homozygous had clinical features of hemochromatosis, and one quarter had serum ferritin levels that remained normal over a four-year period.

European Journal of Cancer, 2004

Breast cancer risk may be associated with folate status or the C677T genotype of the methylenetet... more Breast cancer risk may be associated with folate status or the C677T genotype of the methylenetetrahydrofolate reductase (MTHFR) gene. We compared serum folate concentrations and C677T genotype in 141 breast cancer patients and 109 age-matched controls. Serum folate was significantly lower in cases compared to controls (geometric means, 5.7 versus 6.6 mg/l; P=0.005). Breast cancer risk was not associated with C677T genotype. After adjusting for age of menarche, parity, alcohol intake and total fat intake we observed reductions in odds ratios for breast cancer risk comparing the highest with the lowest quartiles of serum folate concentrations of 0.23 (95% confidence interval (CI) 0.09, 0.54) for the entire group, 0.27 (CI 0.09, 0.80) for the wild-type and 0.08 (CI 0.01, 0.52) for the heterozygous C677T genotype. We conclude that for the whole group, and the wild-type and heterozygous C677T genotypes, increased serum concentrations of folate were associated with reduced risks of breast cancer. #

Background: Heterozygotes for the C282Y mutation of the HFE gene may have altered hematology indi... more Background: Heterozygotes for the C282Y mutation of the HFE gene may have altered hematology indices and higher iron stores than wild-type subjects. Methods: We performed a cross-sectional analysis of 1488 females and 1522 males 20 -79 years of age drawn from the Busselton (Australia) population study to assess the effects of HFE genotype, age, gender, and lifestyle on serum iron and hematology indices. Results: Male C282Y heterozygotes had increased transferrin saturation compared with the wild-type genotype. Neither male nor female heterozygotes had significantly increased ferritin values compared with the wild-type genotype. Younger (20 -29 years) wild-type males, but not heterozygous males, had significantly lower ferritin values than wild-type males in the older age groups. Compound heterozygous subjects had increased means for serum iron, transferrin saturation, corpuscular volume, and corpuscular hemoglobin compared with the wild-type genotype, and the males also had increased ferritin values (medians 323 vs 177 g/L; P ‫؍‬ 0.003). In both male and female wild-type subjects, an increased body mass index was associated with decreased serum iron and transferrin saturation and increased ferritin values. There was a significant increase in ferritin concentrations in both genders with increasing frequency of red meat consumption above a baseline of 1-2 times per week and alcohol intakes >10 g/day. Conclusions: Male C282Y heterozygotes had significantly increased transferrin saturation values. Compound heterozygous (C282Y/H63D) subjects formed a separate category of C282Y heterozygotes in whom both iron and red cell indices were significantly increased compared with the wild-type genotype. Nonstandard abbreviations: wt, wild type; MCV, mean corpuscular volume; MCH, mean corpuscular hemoglobin; and BMI, body mass index.

Gastroenterology, 2002

Two major mutations are defined within the hemochromatosis gene, HFE. Although the effects of the... more Two major mutations are defined within the hemochromatosis gene, HFE. Although the effects of the C282Y mutation have been well characterized, the effects of the H63D mutation remain unclear. We accessed a well-defined population in Busselton, Australia, and determined the frequency of the H63D mutation and its influence on total body iron stores. Serum transferrin saturation and ferritin levels were correlated with the H63D mutation in 2531 unrelated white subjects who did not possess the C282Y mutation. Sixty-two subjects (2.1%) were homozygous for the H63D mutation, 711 (23.6%) were heterozygous, and 1758 (58.4%) were wild-type for the H63D mutation. Serum transferrin saturation was significantly increased in male and female H63D homozygotes and heterozygotes compared with wild-types. Serum ferritin levels within each gender were not influenced by H63D genotypes. Elevated transferrin saturation &amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;gt; or = 45% was observed in a greater proportion of male H63D carriers than male wild-types. Male H63D homozygotes (9%) and heterozygotes (3%) were more likely to have both elevated transferrin saturation and elevated ferritin &amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;gt; or = 300 ng/mL than male wild-types (0.7%). Homozygosity for H63D was not associated with the development of clinically significant iron overload. Presence of the H63D mutation results in a significant increase in serum transferrin saturation but does not result in significant iron overload. In the absence of the C282Y mutation, the H63D mutation is not clinically significant.

Background: Women who inherit heterozygosity for the C282Y mutation of the HFE gene may have incr... more Background: Women who inherit heterozygosity for the C282Y mutation of the HFE gene may have increased serum iron indices and hemoglobin and are less likely to develop iron deficiency compared with women with the wild-type genotype. Methods: We performed a cross-sectional analysis of 497 women 20 -44 years of age and 830 women >51 years of age drawn from the Busselton (Australia) population study to assess the effects of the HFE genotype on serum iron and hematology indices. Results: Heterozygosity for the C282Y mutation occurred in 13.8% of the study population, comprising 11.8% C282Y wild-type heterozygotes and 2.0% C282Y/ H63D compound heterozygotes. In the younger age group, C282Y wild-type women did not have significantly increased serum iron, transferrin saturation, or hemoglobin values, and were not protected from developing iron deficiency, compared with women of the same age with the wild-type genotype. Young compound heterozygous women had higher means for serum iron (25.0 vs 16.9 mol/L; P <0.001), transferrin saturation (42.0% vs 25.6%; P <0.05), hemoglobin (139.4 vs 132.3 g/L; P <0.05), and corpuscular volume (91.1 vs 87.7 fL; P <0.05), and a higher median ferritin (53 vs 44

Analytical Biochemistry, 2006

Few methods for assessing total antioxidant capacity (TAC) include both the percentage of inhibit... more Few methods for assessing total antioxidant capacity (TAC) include both the percentage of inhibition and the length of inhibition in the measurement. Available methods require above ambient constant temperature incubation, reaction preheating, and/or separate assays for testing hydrophilic and hydrophobic samples. We describe a high-throughput method, antioxidant inhibition of oxygen radicals (AIOR), that overcomes these difficulties. AIOR uses peroxyl radicals to trigger a decrease in fluorescence of the indicator molecule, uroporphyrin I, which is delayed by the presence of antioxidants. The area under the curve is measured by a fluorescence spectrophotometer in a 96-well microplate format, and TAC results are expressed as millimole/liter Trolox equivalents. AIOR is performed at ambient temperature and is applicable to samples in either aqueous or common organic solvents. The reaction between uroporphyrin I and the peroxyl radicals generated from 2,2 0 -azobis(2-amidinopropane) dihydrochloride (AAPH) was found to be of first-order kinetics with a mean rate constant (k) of 0.0254. Applications to measure antioxidant capacity are demonstrated on individual chemicals and biological samples. The method has good linearity, within-and between-assay precision, and recovery. Crown

Chronic liver disease is characterised by liver fibrosis, which may lead to cirrhosis. Convention... more Chronic liver disease is characterised by liver fibrosis, which may lead to cirrhosis. Conventional serum-based liver function tests do not give information on either the presence or the rate of progress of liver fibrosis. The reference diagnostic test to detect fibrosis is liver biopsy, a procedure subject to various limitations, including risk of patient injury and sampling error.

Diabetes Care, 2008

OBJECTIVE -To examine the relationship between iron status, hereditary hemochromatosis (HFE) gene... more OBJECTIVE -To examine the relationship between iron status, hereditary hemochromatosis (HFE) gene mutations, and clinical features and outcomes of type 2 diabetes in a wellcharacterized representative sample of community-based patients.

Journal of Gastroenterology and Hepatology, 2002

Background: Two mutations in a newly described gene, HFE, have been proposed as genetic markers f... more Background: Two mutations in a newly described gene, HFE, have been proposed as genetic markers for the inherited iron overload disease, genetic haemochromatosis.Methods: We assessed the frequency of both mutations in a cohort of genetic haemochromatosis patients and compared these with a control population. The patients were genetic haemochromatosis patients from Western Australia whose diagnosis met strict criteria for phenotypic expression. Control patients had other liver disease where iron overload was excluded.Results: Genomic DNA of 72 genetic haemochromatosis patients and 69 controls was examined for the C282Y and H63D mutations of the HFE gene using polymerase chain reaction amplification and restriction enzyme digestion. In genetic haemochromatosis patients, the C282Y mutation was homozygous in 64 of 72, giving a sensitivity of 89% (95% confidence interval 82–96%), heterozygous in five (7%) and absent in another three (4%), whereas none of the control subjects were homozygous. The H63D mutation was present in one genetic haemochromatosis patient and was not useful as a diagnostic marker. In this cohort of Western Australian patients with phenotypic expression of genetic haemochromatosis, the specificity of a homozygous C282Y mutation for genetic haemochromatosis was 100%.Conclusions: The results indicate that genotyping for the C282Y mutation is a useful test for the diagnosis of genetic haemochromatosis in clinical practice.

We performed a case control study to assess the association between serum micronutrient and antio... more We performed a case control study to assess the association between serum micronutrient and antioxidant levels and the risk of breast cancer. Newly diagnosed breast cancer cases were recruited before any treatment and matched with controls randomly selected from the electoral roll. Blood samples were collected from 153 breast cancer cases and 151 controls. Serum samples were analyzed for retinol, ␣-tocopherol, lycopene, ␣and ␤-carotene by HPLC, and total antioxidant status by the Troloxequivalent antioxidant assay. Serum albumin, bilirubin and uric acid levels were also determined. After adjustment for age at menarche, parity, dietary fat and alcohol intake, we observed the following reductions in odds ratios for breast cancer risk comparing the highest with the lowest quartiles: 0.47 [95% confidence interval (CI) 0.24, 0.91] for ␤-carotene; 0.53 (CI 0.28, 1.01) for retinol; 0.50 (CI 0.26, 0.97) for bilirubin and 0.47 (CI 0.24, 0.94) for total antioxidant status. We conclude that increased serum levels of ␤-carotene, retinol, bilirubin and total antioxidant status are associated with reductions in breast cancer risk. J. Nutr. 132: 303-306, 2002.