Machine learning and genetic algorithm prediction of energy differences between electronic calculations of graphene nanoflakes.

Computational screening is key to understanding structure-function relationships at the nanoscale but the high computational cost of accurate electronic structure calculations remains a bottleneck for the screening of large nanomaterial libraries. In this work we propose a data-driven strategy to predict accuracy differences between different levels of theory. Machine learning (ML) models are trained with structural features of graphene nanoflakes to predict the differences between electronic properties at two levels of approximation. The ML models yield an overall accuracy of 94% and 88%, for energy of the Fermi level and the band gap, respectively. This strategy represents a successful application of established ML methods to the selection of optimum level of theory, enabling more rapid and efficient screening of nanomaterials, and is extensible to other materials and computational methods.

Graphene-like Two-Dimensional Ionic Boron with Double Dirac Cones at Ambient Condition.

Recently, partially ionic boron (γ-B28) has been predicted and observed in pure boron, in bulk phase and controlled by pressure [ Nature 2009 , 457 , 863 ]. By using ab initio evolutionary structure search, we report the prediction of ionic boron at a reduced dimension and ambient pressure, namely, the two-dimensional (2D) ionic boron. This 2D boron structure consists of graphene-like plane and B2 atom pairs with the P6/mmm space group and six atoms in the unit cell and has lower energy than the previously reported α-sheet structure and its analogues. Its dynamical and thermal stability are confirmed by the phonon-spectrum and ab initio molecular dynamics simulation. In addition, this phase exhibits double Dirac cones with massless Dirac Fermions due to the significant charge transfer between the graphene-like plane and B2 pair that enhances the energetic stability of the P6/mmm boron. A Fermi velocity (vf) as high as 2.3 × 10(6) m/s, which is even higher than that of graphene (0.82 × 10(6) m/s), is predicted for the P6/mmm boron. The present work is the first report of the 2D ionic boron at atmospheric pressure. The unique electronic structure renders the 2D ionic boron a promising 2D material for applications in nanoelectronics.

A phase 3 trial evaluating panitumumab plus best supportive care vs best supportive care in chemorefractory wild-type KRAS or RAS metastatic colorectal cancer.

BACKGROUND: We assessed the treatment effect of panitumumab plus best supportive care (BSC) vs BSC on overall survival (OS) in patients with chemorefractory wild-type KRAS exon 2 metastatic colorectal cancer (mCRC) and report the first prospective extended RAS analysis in a phase 3 trial. METHODS: Patients with wild-type KRAS exon 2 mCRC were randomised 1 : 1 to panitumumab (6 mg kg-1 Q2W) plus BSC or BSC. On-study crossover was prohibited. RAS mutation status was determined by central laboratory testing. The primary endpoint was OS in wild-type KRAS exon 2 mCRC; OS in wild-type RAS mCRC (KRAS and NRAS exons 2, 3, and 4) was a secondary endpoint. RESULTS: Three hundred seventy seven patients with wild-type KRAS exon 2 mCRC were randomised. Median OS was 10.0 months with panitumumab plus BSC vs 7.4 months with BSC (HR=0.73; 95% CI=0.57-0.93; P=0.0096). RAS ascertainment was 86%. In wild-type RAS mCRC, median OS for panitumumab plus BSC was 10.0 vs 6.9 months for BSC (HR=0.70; 95% CI=0.53-0.93; P=0.0135). Patients with RAS mutations did not benefit from panitumumab (OS HR=0.99; 95% CI=0.49-2.00). No new safety signals were observed. CONCLUSIONS: Panitumumab significantly improved OS in wild-type KRAS exon 2 mCRC. The effect was more pronounced in wild-type RAS mCRC, validating previous retrospective analyses.

Two-Dimensional Boron Hydride Sheets: High Stability, Massless Dirac Fermions, and Excellent Mechanical Properties.

Two-dimensional (2D) boron sheets have been successfully synthesized in recent experiments, however, some important issues remain, including the dynamical instability, high energy, and the active surface of the sheets. In an attempt to stabilize 2D boron layers, we have used density functional theory and global minimum search with the particle-swarm optimization method to predict four stable 2D boron hydride layers, namely the C2/m, Pbcm, Cmmm, and Pmmn sheets. The vibrational normal mode calculations reveal all these structures are dynamically stable, indicating potential for successful experimental synthesis. The calculated Young's modulus indicates a high mechanical strength for the C2/m and Pbcm phases. Most importantly, the C2/m, Pbcm, and Pmmn structures exhibit Dirac cones with massless Dirac fermions and the Fermi velocities for the Pbcm and Cmmm structures are even higher than that of graphene. The Cmmm phase is reported as the first discovery of Dirac ring material among boron-based 2D structures. The unique electronic structure of the 2D boron hydride sheets makes them ideal for nanoelectronics applications.

Isoindigo-Based Small Molecules with Varied Donor Components for Solution-Processable Organic Field Effect Transistor Devices.

Two solution-processable small organic molecules, (E)-6,6'-bis(4-(diphenylamino)phenyl)-1,1'-bis(2-ethylhexyl)-(3,3'-biindolinylidene)-2,2'-dione (coded as S10) and (E)-6,6'-di(9H-carbazol-9-yl)-1,1'-bis(2-ethylhexyl)-(3,3'-biindolinylidene)-2,2'-dione (coded as S11) were successfully designed, synthesized and fully characterized. S10 and S11 are based on a donor-acceptor-donor structural motif and contain a common electron accepting moiety, isoindigo, along with different electron donating functionalities, triphenylamine and carbazole, respectively. Ultraviolet-visible absorption spectra revealed that the use of triphenylamine donor functionality resulted in an enhanced intramolecular charge transfer transition and reduction of optical band gap, when compared with its carbazole analogue. Both of these materials were designed to be donor semiconducting components, exerted excellent solubility in common organic solvents, showed excellent thermal stability, and their promising optoelectronic properties encouraged us to scrutinize charge-carrier mobilities using solution-processable organic field effect transistors. Hole mobilities of the order of 2.2 × 10(-4) cm²/Vs and 7.8 × 10(-3) cm²/Vs were measured using S10 and S11 as active materials, respectively.

Significant Improvement of Optoelectronic and Photovoltaic Properties by Incorporating Thiophene in a Solution-Processable D-A-D Modular Chromophore.

Through the incorporation of a thiophene functionality, a novel solution-processable small organic chromophore was designed, synthesized and characterized for application in bulk-heterojunction solar cells. The new chromophore, (2Z,2'Z)-2,2'-(1,4-phenylene)bis(3-(5-(4-(diphenylamino)phenyl)thiophen-2-yl)acrylonitrile) (coded as AS2), was based on a donor-acceptor-donor (D-A-D) module where a simple triphenylamine unit served as an electron donor, 1,4-phenylenediacetonitrile as an electron acceptor, and a thiophene ring as the π-bridge embedded between the donor and acceptor functionalities. AS2 was isolated as brick-red, needle-shaped crystals, and was fully characterized by ¹H- and (13)C-NMR, IR, mass spectrometry and single crystal X-ray diffraction. The optoelectronic and photovoltaic properties of AS2 were compared with those of a structural analogue, (2Z,2'Z)-2,2'-(1,4-phenylene)bis(3-(4-(diphenylamino)phenyl)-acrylonitrile) (AS1). Benefiting from the covalent thiophene bridges, compared to AS1 thin solid film, the AS2 film showed: (1) an enhancement of light-harvesting ability by 20%; (2) an increase in wavelength of the longest wavelength absorption maximum (497 nm vs. 470 nm) and (3) a narrower optical band-gap (1.93 eV vs. 2.17 eV). Studies on the photovoltaic properties revealed that the best AS2-[6,6]-phenyl-C61-butyric acid methyl ester (PC61BM)-based device showed an impressive enhanced power conversion efficiency of 4.10%, an approx. 3-fold increase with respect to the efficiency of the best AS1-based device (1.23%). These results clearly indicated that embodiment of thiophene functionality extended the molecular conjugation, thus enhancing the light-harvesting ability and short-circuit current density, while further improving the bulk-heterojunction device performance. To our knowledge, AS2 is the first example in the literature where a thiophene unit has been used in conjunction with a 1,4-phenylenediacetonitrile accepting functionality to extend the π-conjugation in a given D-A-D motif for bulk-heterojunction solar cell applications.

A non-fullerene electron acceptor based on fluorene and diketopyrrolopyrrole building blocks for solution-processable organic solar cells with an impressive open-circuit voltage.

A novel solution-processable non-fullerene electron acceptor 6,6'-(5,5'-(9,9-dioctyl-9H-fluorene-2,7-diyl)bis(thiophene-5,2-diyl))bis(2,5-bis(2-ethylhexyl)-3-(thiophen-2-yl)pyrrolo[3,4-c]pyrrole-1,4(2H,5H)-dione) (DPP1) based on fluorene and diketopyrrolopyrrole conjugated moieties was designed, synthesized and fully characterized. DPP1 exhibited excellent solubility and high thermal stability which are essential for easy processing. Upon using DPP1 as an acceptor with the classical electron donor poly(3-hexylthiophene), solution processable bulk-heterojunction solar cells afforded a power conversion efficiency of 1.2% with a high open-circuit voltage (1.1 V). As per our knowledge, this value of open circuit voltage is one of the highest values reported so far for a bulk-heterojunction device using DPP1 as a non-fullerene acceptor.

Demographic, anthropometric and socioeconomic characteristics of functional constipation in Eastern Croatia.

Aim of the research is to establish the prevalence of constipation in Osjecko-baranjska County, to establish its specific characteristics and to determine the effect of demographic, anthropometric and socioeconomic factors. It is a cross-sectional study conducted in 2010. on systematic sample of 900 subjects between 20 and 69 years of age. Every subject was sent an invitation letter and a Rome III diagnostic questionnaire for one of the disorders. A scoring algorithm was used to confirm or exclude the diagnosis of functional constipation. The chi-square test (chi2 test), t-test and logistic regression were used for analysis. The prevalence of constipation in our study was 22.19%, which is higher than the prevalence in most other countries, where it ranges from 5% to 18%. In our study statistically significant variables were: place of current residence (urban), education level (high school), marital status (divorced people), a larger number of household members and a lower health status by self-assessment. According to t-test persons with constipation on average are older, have higher average BMI and lower average grade valued financial status of households and their health. There were a greater number of subjects that had at least one alarm symptom or some of the psychosocial factors and they often suffered from a chronic disease. Functional constipation presents a significant health problem. Rome III survey questionnaire proved to be an acceptable method for diagnosing this functional disorder in clinical-consilliary and primary health care, and for persons showing signs of alarm and needing further diagnostic treatment.

Irritable bowel syndrome in Croatia.

There are three epidemiological studies of irritable bowel syndrome (IBS) that were conducted in Croatia (in the area of Zagreb in 2002, Bjelovarsko-bilogorska County in 2008, and finally in Osjecko-baranjska County in 2011). The aim of this study is to analyze the anthropometric, demographic and socioeconomic characteristics of IBS in Croatia comparing these three studies. The studies included a questionnaire based on Rome criteria. Study population matched the adult population of Croatia according last available census (1991, 2001 resp.). Studies showed a high prevalence of IBS and some common factors relevant for development of IBS were determined such as gender, body mass index and lower level of education. There is a need for further investigations in coastal Croatia applying a uniform questionnaire on anthropometric, demographic and socioeconomic characteristics of IBS and Rome III criteria, diagnostic questionnaires and scoring algorithm for functional gastrointestinal disorders developed by Rome Foundation applicable in clinical practice and population studies, regarding the significant high prevalence of IBS in our country.

Anomalous length dependence of the conductance of graphene nanoribbons with zigzag edges.

Charge transport through two sets of symmetric graphene nanoribbons with zigzag shaped edges in a two-terminal device has been investigated, using density functional theory combined with the non-equilibrium Green's function method. The conductance has been explored as a function of nanoribbon length, bias voltage, and the strength of terminal coupling. The set of narrower nanoribbons, in the form of thiolated linear acenes, shows an anomalous length dependence of the conductance, which at first exhibits a drop and a minimum, followed by an evident rise. The length trend is shown to arise because of a gradual transformation in the transport mechanism, which changes from being governed by a continuum of out-of-plane π type and in-plane state channels to being fully controlled by a single, increasingly more resonant, occupied π state channel. For the set of nanoribbons with a wider profile, a steady increase is observed across the whole length range, owing to the absence of the former transport mechanism. The predicted trends are confirmed by the inclusion of self-interaction correction in the calculations. For both sets of nanoribbons the replacement of the strongly coupling thiol groups by weakly bonding phenathroline has been found to cause a strong attenuation with the length and a generally low conductance.

[Classical medications in the treatment of inflammatory bowel diseases]. / Klasicni lijekovi koji se upotrebljavaju u lijecenju upalnih bolesti crijeva.

The treatment of inflammatory bowel diseases is complex and requires individual approach to every single patient. Traditionally, the approach is based on introduction of so called "classical" medication into the treatment regimen, from ones less potent and with fewer side effects to the ones more toxic but also therapeutically more effective. Aminosalicylates were the first choice of treatment for a long time. However, the role of aminosalicylates is becoming more and more diminished, although they are still the drug of choice in the treatment of mild to moderate ulcerative colitis. Corticosteroids are the therapy of choice in treatment of active IBD for achieving remission in moderate to severe disease. Azathioprine and 6- mercaptopurine belong to a group of thiopurines with an immunomodulatory effect which, in Crohn's disease as well as in ulcerative colitis, primarily have a role in a steroid dependant or steroid refractory type of disease and in maintenance of remission. Lately, early introduction of these medications is proposed to enhance the number of patients that remain in remission. Methotrexate is used for the therapy of active and relapsing Crohn's disease and represents an alternative in patients who do not tolerate or do not respond to azathioprine or 6-mercaptopurine therapy. Cyclosporine is used in treating steroid refractory ulcerative colitis and in some patients can postpone the need for colectomy. Antibiotics do not have a proven effect on the course of inflammatory bowel diseases and their primary role is to treat septic complications. Classic medications today represent a standard in the management of inflammatory bowel diseases, and the combination of the previously mentioned drugs often has a more potent effect on the course of the disease than any medication on its own and their combination is still an object of investigations and clinical studies.

[Croatian consensus on the treatment of inflammatory bowel diseases with biologic therapy]. / Hrvatski konsenzus o lijecenju upalnih bolesti crijeva bioloskom terapijom.

Introduction of biologic therapy in clinical practice represented significant progress in the treatment of inflammatory bowel diseases (IBD) because of its proven efficacy and due to the fact that biologics are the first drugs used in the treatment of IBD that can change the natural course of this diseases. At the same time, biologics are very expensive drugs with complex mechanism of action and important side effects and their use requires evidence-based clinical guidelines. These were the reasons that Referral Center of the Croatian Ministry of Health for IBD and the IBD Section of the Croatian Society of Gastroenterology organised Croatian consensus conference that defined guidelines for the treatment of IBD with anti-TNF drugs. The text below includes definitions of IBD, general principles of IBD therapy, comments on the importance of mucosal healing, analysis of reasons for nonresponse and loss of response to anti-TNF drugs, recommendation for the duration of anti-TNF therapy, rules of screening for opportunistic infections prior to anti-TNF therapy, comments on the problems with reproduction in IBD and finally guidelines for the treatment of various phenotypes of IBD including extraintestinal manifestations with anti-TNF therapy.

Nodal tumor volume as a prognostic factor for oral squamous cell carcinoma-a systematic review.

Oral squamous cell carcinoma (OSCC) is a complex disease with a high potential for lymph node metastasis and poor survival rates. Accurate nodal staging is crucial for prognostic assessment and treatment planning in OSCC. Recent research has suggested that nodal tumor volume (NTV) may be a more accurate indicator of nodal disease burden than traditional staging methods. However, the prognostic significance of NTV in OSCC remains unclear. This systematic review aims to evaluate the existing evidence on the relationship between NTV and prognosis in OSCC. A comprehensive search of electronic databases was conducted, and studies meeting inclusion criteria were critically appraised and synthesized. Our review identified 23 studies that investigated the prognostic significance of NTV in OSCC. The majority of studies reported that larger NTV was associated with poorer survival outcomes, although the strength of the association varied. The review also identified several areas for future research, including the standardization of NTV measurement and the integration of NTV into the broader landscape of OSCC management. In conclusion, our review suggests that NTV holds promise as a novel prognostic factor in OSCC, but more research is needed to fully elucidate its potential and inform clinical decision-making.

Anthropological, demographic and socioeconomic characteristics of irritable bowel syndrome.

Irritable bowel syndrome (IBS) in one of the most frequent functional gastrointestinal disorders (FGIDs) with a prevalence in 10 to 20%, of cases in some developed countries. The Rome Foundation has drawn up Rome III criteria, diagnostic questionnaires and scoring algorithm for FGIDs, applicable in clinical practice and population studies. The aim of this research is to determine the presence of IBS in Osjecko-baranjska County and the effect of anthropometric, demographic and socioeconomic factors. 703 subjects selected in the systematic sample filled in the Rome III diagnostic questionnaire for IBS. Prevalence of IBS was recorded in 29.16%, in men in 21.39%, and in women in 36.69% of cases, anxiety and depression in 26.34% and 25.85%. Persons suffering from IBS were on average shorter, weighed less and had a lower BMI than persons not showing signs of IBS. Women have 2.101 times greater chance of risk of IBS, and with an increase in the number of members in the household the risk of IBS increases 1.139 times. Rome III survey questionnaire is an acceptable method for diagnosing IBS and identifying persons showing signs of structural changes in order to provide further treatment.

Clinical and anorectal motility features in chronically constipated children.

Constipation is a common problem in children. It can be a symptom of functional disorder in majority of cases, but sometimes a serious organic disease is a cause of constipation. Anorectal manometry plays an important role in the diagnostic procedure. It can be presumed that some values of manometric parameters could be very useful in treatment plan. The aim of this study was to confirm or exclude such limits in manometric finding, to make a plan of the therapy more accurate. Therefore the group of 81 constipated children was investigated. There were 58 patients suffering from functional constipation and 23 with organic disorders. The age of the patients was 3 to 15 years. Scoring system was applied to estimate severity of constipation and anorectal manometry was performed. Our results did not show significant correlation between clinical symptoms and signs and the values that we obtained using anorectal manometry. But, we recommend anorectal manometry because it is a safe method and contributes to clarify the diagnosis, which is very important for treatment plan.

Seroprevalence of Helicobacter pylori infection in dyspeptic patients.

The objective of the study was to assess the effect of age on the seroprevalence of Helicobacter (H.) pylori infection in dyspeptic patients. The results obtained in the patient group were compared with findings on the seroprevalence of H. pylori infection in 2051 blood donors. Serum samples were tested by the commercial ELISA and CFT assays according to manufacturer's instructions. The mean seroprevalence of H. pylori infection as determined by ELISA/CFT was 64.0%/51.7% in the group of blood donors and 92.3%/89.5% in the group of dyspeptic patients. Study results indicated a higher prevalence of H. pylori infection in dyspeptic patients as compared with blood donors in all age groups. In the patient S group, H. pylori seroprevalence was not age dependent.

Impaired esophageal function in patients with irritable bowel syndrome.

The aim of the study was to determine prevalence of the signs and symptoms related to esophageal dysfunction in irritable bowel syndrome (IBS) patients, and to investigate sensorimotor function impairment based on the esophageal manometry study, thus to determine the correlation between them. The study included 30 patients with IBS, 14 of them with diarrhea (IBSd) and 16 with constipation (IBSc) as a predominant discomfort. Control group consisted of 30 healthy subjects. The patients were included in the study on the basis of the Rome criteria for IBS. In addition to thorough history and physical examination patient underwent esophagogastroduodenoscopy and esophageal manometry. The values of esophageal manometry obtained in healthy subjects served as controls in manometry studies. The patients with IBS suffered a great number of both colonic and extracolonic signs and symptoms, however, there was no statistically significant difference in the prevalence of particular symptoms between the two patient subgroups. In comparison with healthy subjects, the patients suffering from IBS showed pathologically altered values in the majority of parameters of esophageal motility. Comparison of the two subgroups of IBS patients according to esophageal motility characteristics yielded differences in only few of them. The results obtained in the study could explain why the patients with IBS quite commonly complain of the symptoms related to upper gastrointestinal tract, such as heartburn and chest pain of noncardiac genesis. The results also suggest that the IBS might be associated with considerably more extensive smooth muscle or innervation changes than presumed before.

Lower gastrointestinal disorders in patients with irritable bowel syndrome.

Irritable bowel syndrome (IBS) is a functional disorder of the gastrointestinal system characterized by abdominal pain related to bowel emptying, defecation impairment and abdominal distention. The aim of the study was to objectify lower gastrointestinal system disturbances in IBS patients. Thirty IBS patients and 30 healthy subjects were included in the study. IBS patients were divided into two subgroups: IBS with predominant diarrhea (IBSd) and IBS with predominant constipation (IBSc). All study subjects underwent physical examination (including digitorectal examination), standard laboratory testing and anorectal manometry. Endoscopy was performed only in group of IBS patients. A statistically significant difference was recorded in most manometric parameters between healthy subjects and IBS patients, which was even more pronounced in IBSd patients. Study results showed that the intestinal motility disorder underlying IBS could be objectified by use of anorectal manometry.

Clinical course of uremic neuropathy in long-term hemodialysis.

One hundred and thirty-one patients on long-term hemodialysis were examined for the presence of clinical symptoms and signs, and for the effects of dialytic age, age and sex on uremic neuropathy. According to dialysis age, the patients were divided into three subgroups: low dialysis age, < 5 years of dialysis (n = 58); intermediate dialysis age, 5-10 years of hemodialysis (n = 39); and high dialysis age, > 10 years of dialysis (n = 34). Two patient subgroups were differentiated according to mean age of 53.2 years: younger (n = 57) and older (n = 74). Clinical grading of uremic neuropathy was based on Nielsen's criteria. The most common symptoms were restless legs syndrome (47%) and cramps (51%). Sensory symptoms were less common in patients on long-term hemodialysis, most common of them being paresthesia (29%) and burning feet syndrome (28%). Abnormal Achilles reflex (53%) and impaired vibration sense (59%) were the most common clinical signs. Clinically manifested uremic neuropathy was present in more than 80% of all study patients, i.e. mild in 41%, and moderate to severe forms of uremic neuropathy according to Nielsen's criteria in 39%. There was no evident effect of dialytic age and sex on the clinical course of uremic neuropathy, however, there was a clear impact of age. It is concluded that long-term hemodialysis does not influence the clinical course of uremic neuropathy unlike evident deterioration of electroneurophysiologic findings.

An efficient non-fullerene acceptor based on central and peripheral naphthalene diimides.

Through the coupling of central and terminal naphthalene diimide functionalities, a unique non-fullerene electron acceptor, coded as N10, was designed, synthesized, characterized and applied in solution-processable bulk-heterojunction devices. The target N10 displayed good solubility, excellent thermal stability and energy levels complementing those of the conventional donor polymer poly(3-hexyl thiophene) (P3HT). An excellent power conversion efficiency of 7.65% was obtained in simple BHJ devices (P3HT : N10 1 : 1.2), which is the highest observed so far for NDI core-based non-fullerene acceptors.