Editorial: focus on waste-heat harvesting via thermoelectric conversion: materials, devices and systems for sustainable energy technologies.

The focus collection 'Waste-heat harvestingviathermoelectric conversion: Materials, devices and systems for sustainable energy technologies' collates several research articles and a Roadmap highlighting the most recent advances in the field of thermoelectricity from the viewpoint of both basic and applied research, with a special eye on the work of the Italian community.

Publisher Correction: Fe-functionalized paramagnetic sporopollenin from pollen grains: one-pot synthesis using ionic liquids.

An amendment to this paper has been published and can be accessed via a link at the top of the paper.

Fe-functionalized paramagnetic sporopollenin from pollen grains: one-pot synthesis using ionic liquids.

The preparation of Fe-decorated sporopollenins was achieved using pollen grains and an ionic liquid as solvent and functionalizing agent. The integrity of the organic capsules was ascertained through scanning electron microscopy studies. The presence of Fe in the capsule was investigated using FT-IR, X-ray photoemission spectroscopy and energy-dispersive X-ray spectroscopy. Electron paramagnetic resonance and magnetization measurements allowed us to demonstrate the paramagnetic behavior of our Fe-functionalized sporopollenin. A few potential applications of pollen-based systems functionalized with magnetic metal ions via ionic liquids are discussed.

Polychromatic emission in a wide energy range from InP-InAs-InP multi-shell nanowires.

InP-InAs-InP multi-shell nanowires (NWs) were grown in the wurtzite (WZ) or zincblende (ZB) crystal phase and their photoluminescence (PL) properties were investigated at low temperature (≈6 K) for different measurement geometries. PL emissions from the NWs were carefully studied in a wide energy range from 0.7 to 1.6 eV. The different features observed in the PL spectra for increasing energies are attributed to four distinct emitting domains of these nano-heterostructures: the InAs island (axially grown), the thin InAs capping shell (radially grown), the crystal-phase quantum disks arising from the coexistence of InP ZB and WZ segments in the same NW, and the InP portions of the NW. These results provide a useful frame for the rational implementation of InP-InAs-InP multi-shell NWs containing various quantum confined domains as polychromatic optically active components in nanodevices for quantum information and communication technologies.

Crystal Phases in Hybrid Metal-Semiconductor Nanowire Devices.

We investigate the metallic phases observed in hybrid metal-GaAs nanowire devices obtained by controlled thermal annealing of Ni/Au electrodes. Devices are fabricated onto a SiN membrane compatible with transmission electron microscopy studies. Energy dispersive X-ray spectroscopy allows us to show that the nanowire body includes two Ni-rich phases that thanks to an innovative use of electron diffraction tomography can be unambiguously identified as Ni3GaAs and Ni5As2 crystals. The mechanisms of Ni incorporation leading to the observed phenomenology are discussed.

Tunable Esaki Effect in Catalyst-Free InAs/GaSb Core-Shell Nanowires.

We demonstrate tunable bistability and a strong negative differential resistance in InAs/GaSb core-shell nanowire devices embedding a radial broken-gap heterojunction. Nanostructures have been grown using a catalyst-free synthesis on a Si substrate. Current-voltage characteristics display a top peak-to-valley ratio of 4.8 at 4.2 K and 2.2 at room temperature. The Esaki effect can be modulated-or even completely quenched-by field effect, by controlling the band bending profile along the azimuthal angle of the radial heterostructure. Hysteretic behavior is also observed in the presence of a suitable resistive load. Our results indicate that high-quality broken-gap devices can be obtained using Au-free growth.

Local noise in a diffusive conductor.

The control and measurement of local non-equilibrium configurations is of utmost importance in applications on energy harvesting, thermoelectrics and heat management in nano-electronics. This challenging task can be achieved with the help of various local probes, prominent examples including superconducting or quantum dot based tunnel junctions, classical and quantum resistors, and Raman thermography. Beyond time-averaged properties, valuable information can also be gained from spontaneous fluctuations of current (noise). From these perspective, however, a fundamental constraint is set by current conservation, which makes noise a characteristic of the whole conductor, rather than some part of it. Here we demonstrate how to remove this obstacle and pick up a local noise temperature of a current biased diffusive conductor with the help of a miniature noise probe. This approach is virtually noninvasive for the electronic energy distributions and extends primary local measurements towards strongly non-equilibrium regimes.

Observing and preventing rubidium runaway in a direct-infusion xenon-spin hyperpolarizer optimized for high-resolution hyper-CEST (chemical exchange saturation transfer using hyperpolarized nuclei) NMR.

Xenon is well known to undergo host-guest interactions with proteins and synthetic molecules. As xenon can also be hyperpolarized by spin exchange optical pumping, allowing the investigation of highly dilute systems, it makes an ideal nuclear magnetic resonance probe for such host molecules. The utility of xenon as a probe can be further improved using Chemical Exchange Saturation Transfer using hyperpolarized nuclei (Hyper-CEST), but for highly accurate experiments requires a polarizer and xenon infusion system optimized for such measurements. We present the design of a hyperpolarizer and xenon infusion system specifically designed to meet the requirements of Hyper-CEST measurements. One key element of this design is preventing rubidium runaway, a chain reaction induced by laser heating that prevents efficient utilization of high photon densities. Using thermocouples positioned along the pumping cell we identify the sources of heating and conditions for rubidium runaway to occur. We then demonstrate the effectiveness of actively cooling the optical cell to prevent rubidium runaway in a compact setup. This results in a 2-3-fold higher polarization than without cooling, allowing us to achieve a polarization of 25% at continuous flow rates of 9 ml/min of (129)Xe. The simplicity of this design also allows it to be retrofitted to many existing polarizers. Combined with a direction infusion system that reduces shot-to-shot noise down to 0.56% we have captured Hyper-CEST spectra in unprecedented detail, allowing us to completely resolve peaks separated by just 1.62 ppm. Due to its high polarization and excellent stability, our design allows the comparison of underlying theories of host-guest systems with experiment at low concentrations, something extremely difficult with previous polarizers.

Urinary polycyclic aromatic hydrocarbons and monohydroxy metabolites as biomarkers of exposure in coke oven workers.

OBJECTIVES: To assess exposure to polycyclic aromatic hydrocarbons (PAHs) using 13 unmetabolised PAHs (U-PAHs) and 12 monohydroxy metabolites (OHPAHs) in urine, and to compare the utility of these biomarkers. METHODS: 55 male Polish coke oven workers collected urine spot samples after a workshift. U-PAHs (naphthalene, acenaphtylene, acenaphthene, fluorene, phenanthrene, anthracene, fluoranthene, pyrene, benzo[a]anthracene, chrysene, benzo[k]fluoranthene, benzo[b]fluoranthene, benzo[a]pyrene) were determined by automatic solid phase micro-extraction followed by gas chromatography/mass spectrometry (GC/MS). OHPAHs (1- and 2-hydroxynaphthalene, 2- and 9-hydroxyfluorene, 4-, 9-, 3-, 1- and 2-hydroxyphenanthrene, 1-hydroxypyrene, 6-hydroxychrysene, 3-hydroxybenzo[a]pyrene) were determined, after liquid/liquid extraction and derivatisation, by GC/MS. RESULTS: U-PAHs from naphthalene to chrysene were found in 100% of samples, and heavier U-PAHs in 7-22% of samples. OHPAHs up to 1-hydroxypyrene were found in 100% of samples, while 6-hydroxychrysene and 3-hydroxybenzo[a]pyrene were always below the quantification limit. Median naphthalene, phenanthrene, pyrene, chrysene and benzo[a]anthracene levels were 0.806, 0.721, 0.020, 0.032 and 0.035 microg/l, while hydroxynaphthalenes, hydroxyphenanthrenes and 1-hydroxypyrene levels were 81.1, 18.9 and 15.4 microg/l. For each chemical, the ratio between U-PAH and the corresponding OHPAH ranged from 1:26 to 1:1000. Significant correlations between logged values of U-PAHs and OHPAHs, between U-PAHs, and between OHPAHs were found, with Pearson's r ranging from 0.27 to 0.97. CONCLUSION: Current analytical techniques allow specific and simultaneous measurement of several urinary determinants of PAHs in humans. The results of these measurements support the use of U-PAHs as biomarkers of exposure and suggest the spectrum of chemicals to be investigated, including carcinogenic chrysene and benzo[a]anthracene, should be widened.

Fetal and placental chromosomal mosaicism revealed by QF-PCR in severe IUGR pregnancies.

A number of genetic and environmental factors are taken into account as responsible for intrauterine growth restriction (IUGR); nevertheless, the relevance of genetic alteration in IUGR aetiology remains to be determined. The aim of this study was to investigate using a combined cytogenetic-molecular approach, improved by a new application of QF-PCR method, the presence of mosaic chromosomal changes in fetal/placental samples from 12 pregnancies with unexplained severe IUGR. This multiple approach allowed us to reveal and quantify subtle chromosomal mosaicisms with less than 5% of trisomic cells even in cases in which cytogenetic and FISH analyses failed to reveal them. These are three pregnancies with a mosaic trisomy for chromosomes 7, 2 and 14; the former case presented matUPD7 and was previously described in this journal (Placenta 22 (2001) 813) in association with pre- and postnatal growth restriction. It is intriguing that chromosomes 7, 2 and 14 are known or suspected to harbour imprinted genes, so that an unbalanced gene dosage in a subset of cells during embryonic development could lead to an early impairment of placental function. Our findings indicate that extensive molecular and cytogenetic studies of IUGR fetal and placental tissues are necessary to reveal at least part of the heterogeneous genetic lesions implicated in IUGR phenotypes.

Post-zygotic origin of complete maternal chromosome 7 isodisomy and consequent loss of placental PEG1/MEST expression.

Maternal UPD of chromosome 7 is associated with pre- and postnatal growth retardation (IUGR, PNGR) and Silver-Russell syndrome (SRS [MIM 180860]). We report a case of IUGR in a newborn with SRS stigmata. Using combined haplotyping and cytogenetic-FISH studies we characterized the lymphocytes, umbilical cord and four placental cotyledons. The results are consistent with complete maternal isodisomy 7 and trisomy 7 mosaicism of post-zygotic origin. The trisomic cell line was prevalent in trophoblast cells from two placental cotyledons. Trisomy 7 of post-zygotic origin is a frequent finding, but maternal isodisomy 7, due to trisomic rescue has never been reported. PEG1/MEST expression was evaluated on placenta cDNA and a specific transcript was revealed only in the cotyledons with a high percentage of trisomic cells and the presence of the paternal chromosome 7 contribution, but not in the placental biopsies with maternal isodisomy 7. The histological features of the four placental fragments revealed that isodisomy 7 correlates with a pattern of cotyledonary hyper-ramification due to an increase of the branching angiogenesis, which could be the result of a defect of angiogenesis caused by the absence of PEG1 product. The severe hypo-ramification of the two cotyledons, showing trisomy 7 mosaicism, may be due to the triplicate dosage of genes on chromosome 7. The delayed fetal growth could be the phenotypic effect of the imbalance between imprinted and non-imprinted genes on chromosome 7 in the fetus or the result of abnormal placental function during pregnancy.

Blood fetal microchimerism in primary biliary cirrhosis.

The autoimmune nature of primary biliary cirrhosis (PBC) is well established. We tested the hypothesis that fetal microchimerism indicated by the persistence of circulating fetal cells in women years after pregnancy might contribute to the aetiopathogenesis of PBC through a graft-versus-host-like response. We extracted DNA from the peripheral blood cells of 36 women carefully selected from 173 consecutive PBC patients, who were matched with 36 healthy women by age, age of last son, and number of children. Both patients and controls had to have male offspring, and no history of miscarriages or blood transfusions; they could not be twins. We tested all of the samples for the presence of two specific Y-chromosome sequences (SY154 and SRY) by amplifying DNA in a nested polymerase chain reaction. Y-chromosome-specific DNA was detected in the peripheral blood cell DNA of 13 (36%) of the 36 women with PBC and in 11 (31%) of the 36 healthy controls. The two groups of PBC patients with and without male DNA sequences were similar in terms of their clinical, biochemical, and serological features. Y-chromosome sequences were found in three of the four PBC women with associated systemic sclerosis. All of the 24 Y-positive samples contained SY154 sequences, but only three PBC patients and six controls showed the presence of both SY154 and SRY sequences. This discrepancy may suggest that not only fetal cells but also fragments of fetal DNA are present in maternal circulation. Overall, our data do not support the hypothesis that fetal microchimerism plays a significant role in the onset or progression of PBC.

Losses of heterozygosity in endometrial adenocarcinomas: positive correlations with histopathological parameters.

We analyzed 37 samples of endometrial adenocarcinoma for loss of heterozygosity (LOH) by using a panel of 44 microsatellites located in 29 chromosomal regions. The aim of our study was to investigate the existence of a possible preferential involvement of some tumor suppressor genes in endometrial carcinogenesis. The analysis was performed on tumoral tissue and on a corresponding normal tissue by the use of polymerase chain reaction (PCR) and the comparison of the amplified alleles. We observed significative LOH (>20%) in the chromosomal regions of 2q14 (33.33%), 7q35 (24.00%), 10q22.1 (37. 50%), 11q13-q14 (44.12%), 15q26 (40.63%), 17p13 (25.71%), and 17q21. 3 (37.04%). We defined a 1-cM minimal common deletion in 11q13-q14 between D11S911 and D11S937 markers. A statistical analysis revealed a positive correlation between LOH of 11q13-q14 and clinicopathological data.

Losses of heterozygosity in oral and oropharyngeal epithelial carcinomas.

We analyzed 25 oral and oropharyngeal epithelial carcinomas for loss of heterozygosity (LOH) and microsatellite instability by using 55 oligonucleotide repeat markers located in 45 chromosomal regions. The aim was to identify which chromosomal regions and tumor-suppressor genes (TSGs) are preferentially lost in these tumors and to relate LOH at specific loci to clinicopathologic data. The analysis was performed on tumor tissue and on a corresponding normal tissue (blood lymphocytes) with the use of the polymerase chain reaction technique followed by microsatellite allele separation with denaturing gel electrophoresis. Thirty-two of 45 chromosomal regions demonstrated a significant (>/=20%) incidence of LOH. An allelic loss of >/=50% was found in 9p21 (77.8%), 8p22-23 (70%), 3p12 (61.5%), 1p36.1 and 12q22 (60%), 3q28 (57.1%), 5q23.3 (54.5%), 3p25-26, 3p24, and 7q35 (50%). We did not find any microsatellite instability. Our results suggest that in addition to a group of TSGs, pleiotropic for several tumor types, other suppressor genes are specifically involved in oral and oropharyngeal carcinogenesis.

Cytogenetic abnormalities and microsatellite instability in endometrial adenocarcinoma.

Recently various authors described a new mechanism involved in the genesis of some tumors, which is characterized by a tendency for replication mistakes and by genomic instability of microsatellite repeats. This instability can be revealed through the shift in the electrophoretic mobility of the analyzed fragments, which is due to a different number of repeat units. This phenomenon is widely documented in colorectal tumors of patients affected by hereditary nonpolyposis colorectal carcinoma (HNPCC). We performed a cytogenetic and molecular study of 23 endometrial adenocarcinomas to investigate the presence of genomic instability and to evaluate the possibility of a positive correlation with specific chromosomal changes. The study of genomic instability was performed using 23 microsatellites localized over 8 chromosomes. Genomic instability of microsatellites was observed in 3 cases over all 8 analyzed chromosomes. The tumoral stage of cases with microsatellite instability does not differ significantly from the remaining tumors. As a matter of fact several cases showing no evidence of instability were more advanced (II B, III A) than tumors with instability. In ten cases we observed trisomy of chromosome 10, in some as a sole anomaly. The 3 cases with genomic instability revealed a near-diploid karyotype and all showed the presence of a supernumerary marker derived from chromosome 1 rearrangements. A derivative chromosome 1 was revealed in 4 cases without evidence of microsatellite instability. It should be noted that the presence of many unidentified markers and the small number of tumors with instability do not allow us to give a definitive significance to this observation. Our results indicate that there is not an apparent correlation between microsatellite instability and specific chromosomal abnormalities. Moreover, we did not find any correlation between pathological characteristics of the tumor and genomic instability. Microsatellite instability appears to be a relatively rare event in endometrial carcinoma.

HIV-1 proviral DNA polymerase chain reaction detection in chorionic villi after exclusion of maternal contamination by variable number of tandem repeats analysis.

OBJECTIVE: The study of the placental HIV infection in cases of seropositive pregnant women after exclusion of maternal contamination of chorionic villi samples by variable number of tandem repeats (VNTR) analysis. METHODS: We studied 30 HIV-positive women: 17 terminated their pregnancy (11 in the first trimester and six in the second) and 13 delivered at term (one was a twin gestation). We selected chorionic villi and ruled out maternal contamination by VNTR analysis. DNA from chorionic villi and cord and maternal blood were tested for HIV by PCR. All infants underwent a paediatric follow-up. RESULTS: All maternal blood samples tested positive for HIV-1 by polymerase chain reaction. No maternal contamination was revealed and HIV was found in six out of 11 first trimester placentas, in all second trimester samples, and in 10 out of 14 at term. Cord blood tested positive in all second trimester cases and in seven out of 14 liveborns. In no case was HIV found in cord blood without infection of the corresponding placenta; conversely, three placentas tested positive but cord blood was negative. Two infants were HIV-positive, 11 were uninfected (one case was lost to follow-up). CONCLUSION: Our study indicates that HIV-1 can infect the placenta from first trimester onwards. HIV was found in two-thirds of our cord blood samples but it is possible that some viral DNA in cord blood may have come from infected placental cells. Additional studies are needed to assess the source of HIV in cord blood and the possible contribution of placental or maternal cells infected with HIV to vertical transmission of the virus.

Genetic amniocentesis in biamniotic twin pregnancies by a single transabdominal insertion of the needle.

We present a technique to aspirate amniotic fluid from both sacs in biamniotic twin pregnancies using a single abdominal insertion with a spinal needle. It was successful in 48 out of 55 cases of biamniotic twin pregnancies referred to our perinatal unit between 1985 and 1994. The single insertion technique was used when the inter-amniotic membrane was clearly evident and two separate free amniotic fluid pools could be reached by the operator with a single puncture. An adequate amount of amniotic fluid was sampled from both sacs to make a cytogenetic diagnosis in all cases. There were four fetuses with trisomy 21 in three twin pregnancies. In two cases, only one twin was affected whilst the co-twin was normal, so that a selective feticide was performed. No miscarriages due to genetic amniocentesis were reported. After 1990, all genetic amniocenteses in biamniotic twin pregnancies (except for one case due to late booking) were performed between 14 and 15 weeks of gestation and with all cases except one, it was possible to sample both twins by a single puncture. We suggest that early amniocentesis (14-15 weeks) by a single abdominal puncture could be a reliable and safe alternative to first-trimester chorionic villus sampling in twin pregnancies.

Frequency of chromosomal aberrations after exposure to gamma-radiation of human chorionic villi.

We investigated the chromosomal damage induced by in vitro exposure to gamma-rays of uncultured first trimester chorionic villi. Frequency and types of chromosomal aberrations at increasing doses of radiation have been evaluated on cytotrophoblast spontaneous metaphases obtained after a short term incubation. Our results indicate a direct correlation between radiation dose and aberration frequency.

Applicability of DNA isolated from syncytiotrophoblast vesicles to gene amplification and molecular analysis.

Maternal contamination of fetal DNA represents a major problem when highly sensitive molecular techniques are used in the prenatal diagnosis of genetic diseases. For this reason, we have studied the possibility of using DNA isolated from syncytiotrophoblast vesicles as a target of gene amplification (PCR). Three PCR systems were selected which included a repetitive 149 bp fragment of the Y chromosome, the VNTR locus D1S80, and a portion of the beta-globin gene. The results of these experiments indicate that DNA isolated from syncytiotrophoblast vesicles is free of maternal contamination and is suitable for gene amplification and DNA analysis.

Prenatal diagnosis of metabolic diseases on chorionic villi obtained before the ninth week of pregnancy.

Nine pregnancies at risk for various metabolic disorders were monitored by prenatal diagnosis on chorionic villi obtained between the sixth and ninth weeks of pregnancy. A diagnosis of an affected fetus was made in five cases (Sandhoff, Tay-Sachs (2), Pompe's, GM1), while metachromatic leukodystrophy, GM1 (2), and Pompe's were excluded in four cases. It is concluded that chorionic villi are a reliable tissue for prenatal diagnosis of metabolic disorders also when obtained before the ninth week.