Vacancies, self-interstitials, and Frenkel pairs represent the basic point defects in silicon single-crystals and are unavoidably introduced in the ingots during the manufacturing process. In semiconductor technology, several problems are caused by points defects that are not at thermodynamic equilibrium. For this reason, virtually defect-free silicon wafers having a small residual concentration of vacancies in the bulk (“Perfect-vacancy”, or Pv silicon) are solely used for the fabrication of advanced microelectronic devices, whereas similar wafers containing a residual concentration of silicon self-interstitials (Pi silicon) are often regarded as unsuitable substrates for device fabrication. This paper describes the possibility of using Pi silicon wafers, after their conversion to Pv, for those applications requiring only vacancy-rich perfect silicon as the substrate. The conversion from Pi to Pv is achieved in these wafers by using rapid thermal annealing at high temperature to produce Frenkel pairs first and to re-install a specific vacancy concentration in the bulk of the wafer later, thus reassigning a new Pv character to the silicon substrate.

The Continuous-feeding Czochralski (CCz) method and an apparatus comprising multiple quartz crucibles have recently been used to manufacture commercial silicon single-crystals for microelectronics. This paper describes a practical method for calculating and predicting the resistivity in the CCz-silicon crystal as a function of the initial dopant concentration in the silicon melt, the pull rate, the crystal mass and the amount of dopant regularly added to the melt during the growth process. This simplified model considers and includes the silicon mass transport from the outer crucible to the inner crucibles, the concentration of the dopant species added to the melt, the evaporation of the dopant (for volatile species), the impurity segregation to the crystal. Data collected from real crystals grown with the CCz method by using three separated melt zones are also reported here for a comparison with the model.

Only limited data exist on the effect of neutron irradiation on the brittle to ductile transition (BDT) in tungsten. This work investigates the increase in brittle to ductile transition temperature (BDTT) following neutron irradiation to 1.67 displacements per atom, using four-point bend tests over a range of temperatures (623-1173 K) and strain rates (3.5 x 10(-7) - 2.5 x 10(-5) s(-1)). The BDTT was found to increase by 500 K after irradiation. The activation energy for the BDT was determined using Arrhenius analysis of the four-point bend tests. Nanoindentation strain-rate jump tests were used to characterise the activation volume for dislocation motion. These were quantified as 1.05 eV and 4.6 b(3) respectively, very close to values found for unirradiated tungsten. This suggests that kink-pair formation is the controlling mechanism for the BDT before and after irradiation. This work also carries out a unique verification of inventory-code-modelling (via FISPACT-II) of transmutation of tungsten to rhenium and osmium under neutron irradiation using two independent techniques (X-ray and gamma-ray spectroscopy). These results show that modelling can correctly predict this transmutation, provided that an accurate neutron spectrum is used. This is a critical result given the widespread use of inventory codes such as FISPACT-II, and the associated nuclear data libraries, for modelling transmutation of tungsten. (C) 2019 The Authors. Published by Elsevier B.V.

Heavily doped silicon substrates are widely used for the fabrication of discrete devices for power applications. The basic wafer template is generally composed of an epitaxial layer over a heavily doped silicon substrate whose dopant type and resistivity vary depending on the final device characteristics but, in either case of P- and N-type substrates, the demand is more and more oriented towards very low resistivity ranges, such as 0.5-5 mΩ·cm, in order to minimize the substrate contribution to the transistor drain-source resistance. Furthermore, the continuous effort to reduce manufacturing costs is moving discrete device fabrication from 100-150 mm in wafer diameter to 200 mm and even to 300 mm. Often a vertical device structure is chosen, where the electric current flows through the entire wafer thickness, therefore the properties of the wafer bulk affect the device performance and the bulk defectivity level have to be understood and controlled carefully. This paper focuses on the microdefect formation in heavily donor-doped silicon, and, in particular, on the behaviour of oxygen precipitation in heavily arsenic-doped silicon. A challenge when dealing with experimental investigations on the behaviour of oxygen in heavily donor-doped silicon is the difficulty of decoupling the oxygen level and the dopant concentration level during crystal growth. Differently from the case of lightly doped or even of heavily boron-doped crystals, during the growth of silicon crystals heavily doped with volatile donors, such as arsenic, antimony or red phosphorus, a strong interaction is unavoidably observed between oxygen and dopant evaporation, leading to a certain degree of correlation between the resulting oxygen level and the dopant concentration level. To overcome this problem, a set of lightly doped silicon samples with similar initial oxygen concentration and growth conditions are included in this study, to discriminate the impact of the oxygen concentration and the impact of the dopant concentration. A wide arsenic concentration range is explored, from 3 × 1018 cm-3 to 4 × 1019 cm-3. The oxygen precipitation is characterized after a thermal cycle of 4 h at 800°C for nuclei stabilization + 16 h at 1000°C for nuclei growth. Oxide precipitates (BMD) are counted under microscope on the cleaved sample surface after preferential etching. A precipitation retardation effect is observed in the arsenic doped samples when the dopant concentration is higher than 1.7x1019 cm-3 compared with lightly doped samples having the same initial oxygen content and grown under similar conditions. The BMD density in the arsenic-doped samples is uniform along the radius, with no rings or cores, contrary to what is commonly observed in lightly doped samples grown with similar V/G values. This finding is discussed by considering the role played by vacancies in the formation of oxygen precipitates and the impact of the arsenic concentration on the equilibrium concentration of point defects in silicon, deduced from the experimentally observed voids revealed as light-scattering surface defects in polished wafers. For arsenic-doped wafers, the voids count first increases but then – at [As] > 1.7x1019 cm-3 - sharply drops. This dependence of counts on concentration can be explained by assuming that the substitutional dopant Ms can trap vacancies by forming vacancy-impurity complexes VMs (trapped vacancies) while a small fraction of interstitial dopant Mi acts as trapped self-interstitials. The net amount of incorporated vacancy species includes the initial concentration difference [VMs] – [Mi]. The VMs species – assumed of the same positive charge state as Ms - provide a dominant contribution at lower [Ms] whereas the negatively charged Mi species dominate at higher [Ms]. Accordingly, the net vacancy concentration increases at first, but then decreases and tends toward zero [1], reducing the number of vacancies available for void formation as well as for assisting BMD nucleation. [1] V. V. Voronkov, R. Falster, M. Porrini, and J. Duchini, Phys. Status Solidi A 209, 1898 (2012)

Objectives and study: It has been reported that the quality of life (QoL) of children with chronic viral hepatitis (CVH) is deteriorated during interferon treatment, although QoL returned to baseline after stopping therapy. Poor data are available on the impact of chronic hepatitis C (CHC) and B (CHB) on QoL of treatment-naïve children or after a long time after stopping treatment. The aim of this study was to assess the Health-Related QoL (HRQoL) of treatment-naïve or previously treated adolescents and young adults with CVH, and to analyze differences between patients with CHC and CHB.

Indium is becoming one of the most important dopant species for silicon crystals used in photovoltaics. In this work we have investigated the behavior of indium in silicon crystals grown by the Czochralski pulling process. The experiments were performed by growing 200 mm crystals, which is a standard diameter for large volume production, thus the data reported here are of technological interest for the large scale production of indium doped p-type silicon. The indium segregation coefficient and the evaporation rate from the silicon melt have been calculated to be 5 x 10(-4) +/- 3% and 1.6 x 10(-4) cm.s(-1), respectively. In contrast to previous works the indium was introduced in liquid phase and the efficiency was compared with that deduced by other authors, using different methods. In addition, the percentage of electrically active indium at different dopant concentrations is calculated and compared with the carrier concentration at room temperature, measured by four-point bulk method. (C) 2016 The Japan Society of Applied Physics

Nosocomial infections are a major public health issue and preventative strategies using probiotics and micronutrients are being evaluated. To investigate the efficacy of a mixture of Lactobacillus GG and micronutrients in preventing nosocomial infections in children. A randomised, double-blind, placebo-controlled trial was conducted in hospitalised children. Children (6 months to 5 years of age) received Lactobacillus GG (6 × 10 9 CFU/day) together with vitamins B and C and zinc or placebo, for 15 days, starting on the first day of hospitalisation. The incidence of gastrointestinal and respiratory nosocomial infections after discharge was determined by follow-up telephone call at 7 days. After 3 months, another telephone call estimated the incidence of further infections during follow-up. Ninety children completed the follow-up. Of 19/90 children with a nosocomial infection (20%), 4/45 children (9%) were in the treatment group and 15/45 (33%) in the placebo group ( P = 0.016). Specifically, 2/45 (4%) children in the treatment group vs. 11/45 (24%) children in the placebo group ( P = 0.007) presented with diarrhoea. The duration of hospitalisation was significantly shorter in the treatment group (3.9 days ± 1.7 vs. 4.9 ± 1.2; P = 0.003). At the follow-up, a total of 11/45 (24.4%) children in the treatment group had at least one episode of infection compared to 22/45 (48.9%) in the placebo group ( P = 0.016). A mixture containing Lactobacillus GG and micronutrients may reduce the incidence of nosocomial infections, supporting the hypothesis that this may represent a valid strategy to prevent nosocomial infections.

Oxygen precipitation in heavily arsenic doped Czochralski silicon is investigated for a wide dopant concentration range (from 3 × 1018 cm–3 to 4 × 1019 cm–3) and it is compared with that observed in lightly doped silicon having similar initial oxygen concentration. A lower density of oxide precipitates after an anneal of 4 h at 800 °C followed by 16 h at 1000 °C is measured in the case of arsenic doped samples, in comparison to lightly doped ones, when the dopant concentration exceeds 1.6 × 1019 cm–3. In addition, no radial bands (rings) of precipitation are observed in arsenic-doped samples, contrary to lightly doped samples grown at the same V/G (ratio between pull rate V and axial thermal gradient G). These findings are explained by considering the role played by vacancies in the formation of oxygen precipitates and the impact of the arsenic concentration on the total concentration of point defects in silicon. Data obtained by computer simulation of microdefect formation in silicon are also presented in support of this explanation. (© 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

Background: Although alterations in thyroid function are reported in obese patients, no study on the ultrasound pattern of thyroid in these patients is available. The aim of this study was to evaluate ultrasound features of thyroid in a large group of obese and nonobese children. Patients and methods: The study was carried out between January and May 2013 in middle-school children of Molise Region. In all subjects, the following anthropometric parameters were assessed: weight, height, waist and hip circumferences, body mass index (BMI), waist-to-hip ratio (WHR), waist-to-height ratio (WHtR). Overweight was defined by BMI = 90 percentile for age and obesity by BMI = 95 percentile for age, according to CDC standards. A WHR > 0.95 in boys and > 0.85 in girls was considered as index of central obesity. A WHtR > 0.5 was used as index of cardiovascular risk (CVR), while a WHtR > 0.59 as index of metabolic syndrome risk (MSR). Thyroid morphology was evaluated by ultrasound (US) with a linear 7.5 MHz probe, by the same observer, well trained in thyroid imaging. Results: Overall, 621 children (310 males, mean age 12.3 ± 1 years) have been enrolled. 93 (15%) children were obese and 96 (15.4%) overweight. Central obesity was detected in 205 (33%) children. 178 (28.7%) children had a CVR, and 43 (6.9%) a MSR. An US pattern suggestive of thyroiditis was found in 51 (8.2%) cases (14 males, 4.5%; 37 females, 11.9%; p < 0.001). The percentage of obese or overweight did not significantly differ between 51 children with thyroid alteration (33.3% of obese/overweight) and 570 children with normal thyroid structure (30.2%). As well, mean BMI did not differ between the two groups (21 ± 4.2 versus 20.8 ± 4.3, respectively). Central obesity was significantly more frequent among children with thyroid alteration (25/51 children, 49%) compared to children without US signs of thyroiditis (180/570, 31.6%) (p = 0.011). CVR and MSR indexes did not differ between the two groups. Conclusion: We found in Molise Region a higher prevalence of thyroid structure alteration in middle-school students compared to the reported prevalence of thyroiditis in Italian children (1–4%). Thyroid morphology alteration did not correlate with BMI and obesity, but with the type of obesity. The presence of central adiposity may be considered as an index of a high risk of thyroid structure alteration in pediatric patients. It has been reported a strong relationship with obesity and markers of inflammation. The systemic inflammation status described in presence of central adiposity might be also involved in thyroid dysfunction and morphological thyroid changes, reported in our study. The determination of thyroid hormones and auto-antibodies is required to support the diagnosis of autoimmune thyroiditis in these children.

Background: The increased interest in probiotics use by physicians is supported on one side by the growing body of literature on probiotics, and on the other hand by their increasing commercial availability. Although there is a global interest in the field, little is known about pediatricians' perceptions regarding the use of probiotics. Aim of this survey-based study was to investigate pediatricians' attitudes and prescribing practices for probiotics in gastrointestinal and non-gastrointestinal illnesses. Methods: An 11 item questionnaire was administered to primary care pediatricians (PCPs) and hospital pediatricians (HPs). It included questions on their perceptions regarding the use of probiotics in gastrointestinal and non-gastrointestinal illnesses, recommendations for the use in their own practice, and probiotics strains commonly prescribed. Results: Sixty-five pediatricians returned the questionnaire, 45 PCPs (mean age 52.7 ± 5.4 years) and 20 HPs (mean age 48.8 ± 10.6 years). Both groups prescribed probiotics frequently, believing in their efficacy and safety mainly in gastrointestinal illnesses. Lactobacillus reuterii and Lactobacillus GG were the most commonly used strains, independently from the disease. The main gastrointestinal indication for the use of probiotics as therapeutic agents was acute gastroenteritis (90%), followed by antibiotic-associated diarrhea (78%) and constipation (60%). We found a different pattern of probiotics use according to the pediatricians' setting. HPs used probiotics mainly for the treatment of acute gastroenteritis (95% vs 62% of PCPs; p = 0.006), antibiotic-associated diarrhea (90% vs 40% of PCPs; p = 0.0002), and functional intestinal disease (50% vs 22% of PCPs; p = 0.02). Probiotics were widely used as therapeutic agents also for non-gastrointestinal conditions. Specifically, the main indication in PCPs group was urinary tract infections (38% vs 10% of HPs; p = 0.02), while in HPs group was atopic disease (45% vs 24% of PCPs; p = 0.09). As for the use of probiotics as preventive therapy, the most common indication in gastrointestinal disorders were antibiotic-associated diarrhea (PCPs 73% vs HPs 35%; p = 0.003), functional intestinal disorders (PCPs 65% vs HPs 40%; p = 0.05), and constipation (PCPs 46%; HPs 50%). In non-gastrointestinal disorders, probiotics were mainly prescribed for prevention of urinary tract infection and atopic disease, without differences between the groups. The main perceived barrier to large probiotic use was the lack of strong scientific evidence either for PCPs or HPs (53% vs 25%; p = 0.03). Conclusions: There is a large use of probiotics by pediatricians in agreement or disagreement with established indications. This study showed that pediatricians recognize a role for probiotics in a variety of illnesses. Considering the efficacy and supporting evidence, programs to implement guidelines are strongly needed to guide the use probiotics in gastrointestinal and non-gastrointestinal conditions.

Since children with chronic diseases represent a primary target for immunization strategies, it is important that their immunization coverage and timeliness of vaccines is optimal. We performed a study to measure immunization coverage and timeliness of vaccines in children with type 1 diabetes, HIV infection, Down syndrome, cystic fibrosis, and neurological diseases. A total of 275 children aged 6 months–18 years were included in the study. Coverage for diphtheria–tetanus–pertussis (DTP), polio (Pol), and hepatitis B (HBV) vaccines approximated 85% at 24 months, while measles–mumps–rubella (MMR) coverage was 62%. Immunization coverage for seasonal influenza was 59%. The analysis of timeliness revealed that there was heterogeneity among children with different chronic diseases. A proportional hazard model showed that children with HIV infection had the longest time to complete three doses of DTP, Pol, and HBV, and those with neurological diseases received the first dose of MMR later than the other categories. Causes of missing or delayed vaccination mostly included a concurrent acute disease. Children with chronic diseases should be strictly monitored for routine and recommended vaccinations, and health care providers and families should be properly informed to avoid false contraindications.

The strain rate dependence of the brittle-to-ductile transition (BDT) temperature was investigated in notched and un-notched miniature bars made of high-purity polycrystalline tungsten and in notched bars of less-pure sintered material. The activation energy, EBDT, for the process controlling the BDT in pure tungsten was equal to 1.0 eV both in un-notched and notched specimens, though the brittle-ductile transition temperature, TBDT, was approximate to 40 K lower at each strain rate for the un-notched samples, indicating that the activation energy, EBDT, is a materials parameter, independent of geometrical factors. The experimental data obtained from pure tungsten are described well by a two-dimensional dislocation-dynamics model of crack-tip plasticity, which is also discussed. For sintered tungsten, EBDT was found to be 1.45 eV; TBDT at a given strain rate was higher than in the pure tungsten by approximate to 90 K, suggesting that the BDT in tungsten is very sensitive to impurity levels.

The objective of this document is to identify and reinforce current recommendations concerning the management of HIV infection in infants and children in the context of good resource availability. All recommendations were graded according to the strength and quality of the evidence and were voted on by the 57 participants attending the first Italian Consensus on Paediatric HIV, held in Siracusa in 2008. Paediatricians and HIV/AIDS care specialists were requested to agree on different statements summarizing key issues in the management of paediatric HIV. The comprehensive approach on preventing mother-to-child transmission (PMTCT) has clearly reduced the number of children acquiring the infection in Italy. Although further reduction of MTCT should be attempted, efforts to personalize intervention to specific cases are now required in order to optimise the treatment and care of HIV-infected children. The prompt initiation of treatment and careful selection of first-line regimen, taking into consideration potency and tolerance, remain central. In addition, opportunistic infection prevention, adherence to treatment, and long-term psychosocial consequences are becoming increasingly relevant in the era of effective antiretroviral combination therapies (ART). The increasing proportion of infected children achieving adulthood highlights the need for multidisciplinary strategies to facilitate transition to adult care and maintain strategies specific to perinatally acquired HIV infection.

Aims: To assess plasma concentrations of folic acid, vitamin B12, and total plasma homocysteine (tHCY) during fasting and after methionine load in young patients with Type 1 diabetes mellitus (T1DM). Methods: We enrolled 41 young patients with T1DM without any sign of microvascular complications and 123 healthy controls in a 1:3 case-control study. Fasting and post-methionine load (PML) tHCY, folic acid, and vitamin B12 levels were measured in both groups. Data regarding chronological age, metabolic control (assessed by mean values of glycated hemoglobin in the last 12 months) and disease duration were also recorded. Results: Fasting and PML tHCY levels were significantly lower in patients than in controls: 7.3±2.7 μmol/l vs 8.3±2.5 μmol/l (p=0.01), and 16.7±5.8 μmol/l vs 17.3±4.3 μmol/l (p=0.01), respectively. No correlation was found between fasting and PML tHCY levels and chronological age, disease duration, metabolic control, and insulin requirement. Patients had significantly higher vitamin B12 levels compared to controls: 767±318 pg/ml vs 628±236 pg/ml (p=0.003), while folic acid turned out to be lower in patients than in controls: 5.3±1.9 nmol/l vs 7.5±2.6 nmol/l (p<0.0001). Conclusions: Adolescents and young adults with T1DM without microvascular complications showed lower tHCY both during fasting and after methionine load. Lower folate concentrations in these patients might benefit from food fortification.

Aims Permanent neonatal diabetes is a rare condition affecting 1 in 300 000-400 000 live births; only in 60% of cases it is possible to identify the genetic defect. The condition of pancreatic agenesis is rarer still. Only two genes are known to determine this phenotype: PDX-1 and PTF1A. Congenital heart defects are among the most common developmental anomalies, affecting 1% of new borns, and the GATA4 gene is less frequently involved in these disorders. An Italian child with pancreatic agenesis and an atrial septal defect was genetically investigated to elucidate whether the association of the two pathologies was casual, or represented a new pancreatic/cardiac syndrome.Methods A panel of pancreas development genes, including GCK, Kir6.2, PTF1A, PDX-1, HNF-1A, NgN3, SOX17, SOX7, SOX9, INS, HNF1-B and SUR1 plus the GATA4 gene, were screened for characterization of pancreatic agenesis and cardiac defect.Results Screening for genes causing permanent neonatal diabetes was negative. A novel mutation in GATA4 (c1512C>T) was detected and functional characterization confirmed a reduced activity of the protein. In the family members, the GATA4 mutation co-segregates with a cardiac phenotype, but not with pancreatic agenesis.Conclusions We describe the first report of pancretic agenesis with an associated cardiac defect and a mutation in the GATA4 gene. We could not establish that the GATA4 mutation was causative for pancreatic agenesis and further genetic investigation to detect the genetic cause of the pancreas agenesis was unsuccessful. We conclude that, the two pathologies are attributable to two independent events.