Long-term effects of irrigation with waste water on soil AM fungi diversity and microbial activities: the implications for agro-ecosystem resilience

The effects of irrigation with treated urban wastewater (WW) on the arbuscular mycorrhizal fungi (AMF) diversity and soil microbial activities were assayed on a long-term basis in a semiarid orange-tree orchard. After 43 years, the soil irrigated with fresh water (FW) had higher AMF diversity than soils irrigated with WW. Microbial activities were significantly higher in the soils irrigated with WW than in those irrigated with FW. Therefore, as no negative effects were observed on crop vitality and productivity, it seems that the ecosystem resilience gave rise to the selection of AMF species better able to thrive in soils with higher microbial activity and, thus, to higher soil fertility.

Short communication: RNASEL alleles and susceptibility to infection by human retroviruses and hepatitis viruses

RNASEL seems to function as an intracellular restriction factor blocking the establishment of infections caused by viral agents. Herein, we investigated whether allelic variants at the RNASEL gene might influence the susceptibility to viral infections or conditions potentially linked to viral agents. The allelic distribution at codon 462 was 139 (33.9%), 204 (49.8%), and 67 (16.3%) for RR, RQ, and QQ, respectively, in 410 individuals in Spain. There were no significant differences comparing 105 blood donors and 71 patients with HIV-1 infection, 27 with chronic hepatitis C, 67 with prostate cancer, and 107 with chronic fatigue syndrome. In contrast, two-thirds of 18 patients with HTLV-1 infection and 15 with chronic hepatitis B harbored RR. Thus, polymorphisms at the RNASEL gene do not seem to influence the susceptibility to common viral infections or conditions potentially of viral etiology. The role in influencing the susceptibility to HTLV-1 or HBV chronic infection warrants further examination in larger patient populations.

[Mixed design for the evaluation of the Mesoamerica Health 2015 initiative]

Since the Salud Mesoamerica 2015 initiative (SM-2015) aim is to improve health and nutrition conditions of those most vulnerable in Mesoamerica, the goal of the evaluation is to generate evidence of the joint effectiveness of a package of interventions designed to improve the health conditions. We propose a mix design for the evaluation, which will allow to know the magnitude of changes attributable to the interventions, as well as the meanings of these changes for the target population, taking into account the specificities of each country. The main axis of this design is a locality panel where information about individuals, households, and health facilities (first and second level) will also be collected. The evaluation design described in this paper was developed between June and December, 2009, and it was integrated during workshops in Cuernavaca (Mexico), Managua (Nicaragua), and San Jose (Costa Rica). The proposed design will allow to generate evidence about the joint effectiveness of the package of interventions proposed for the SM-2015. The success of this design rests on the political commitment of countries and donors.

Radiation dose reduction in a neonatal intensive care unit in computed radiography

The purpose of this study was to evaluate the dose received by chest x-rays in neonatal care with thermoluminescent dosimetry and to determine the level of exposure where the quantum noise level does not affect the diagnostic image quality in order to reduce the dose to neonates. In pediatric radiology, especially the prematurely born children are highly sensitive to the radiation because of the highly mitotic state of their cells; in general, the sensitivity of a tissue to radiation is directly proportional to its rate of proliferation. The sample consisted of 208 neonatal chest x-rays of 12 neonates admitted and treated in a Neonatal Intensive Care Unit (NICU). All the neonates were preterm in the range of 28-34 weeks, with a mean of 30.8 weeks. Entrance Surface Doses (ESD) values for chest x-rays are higher than the DRL of 50 μGy proposed by the National Radiological Protection Board (NRPB). In order to reduce the dose to neonates, the optimum image quality was achieved by determining the level of ESD where level noise does not affect the diagnostic image quality. The optimum ESD was estimated for additional 20 chest x-rays increasing kVp and reducing mAs until quantum noise affects image quality.

Involvement of thyroid hormones in the control of larval metamorphosis in Sicyopterus lagocephalus (Teleostei: Gobioidei) at the time of river recruitment

After oceanic migration, post-larvae of the amphidromous Sicyopterus lagocephalus recruit to rivers in Reunion Island. As they enter the river mouth, post-larvae undergo many morphological, physiological and behavioural changes. These drastic changes, which allow them to change feeding regime and to colonise the juvenile and adult freshwater habitat, are defined as metamorphosis. The endocrine control of these changes has never been investigated in Gobioid fish. Here, we investigated whether thyroid hormones (TH) influence metamorphosis in recruiting S.lagocephalus. An analytical study was first performed on a cohort of 2400 fish caught at post-larval stage 1 and maintained for 37 days after capture in a flume tank (fluvarium), which replicates as closely as possible the natural conditions. Biometrical parameters (total and standard lengths, corner of mouth angle, body mass and condition factor) and whole-body thyroxine (T(4)) and triiodothyronine (T(3)) contents were measured on fish, sampled at regular intervals during these 37 days (192 fish). TH levels, measured by radioimmunoassays, were highest when morphological changes, such as the change in the position of the mouth, were most important. An experimental approach was then used to test the effect of the hormonal treatment (T(4) or thiourea, TU, a TH inhibitor) on biometrical parameters of 576 post-larvae. The change in the position of the mouth was significantly accelerated in the T(4)-treated post-larvae, while it was significantly delayed in the TU-treated post-larvae, compared to controls. Our study suggests that S.lagocephalus post-larva undergoes a true metamorphic event under the control of thyroid hormones at the time of its recruitment into the river.

Transient occult hepatitis B virus infection in a blood donor with high viremia

BACKGROUND

Screening of blood donors for viral nucleic acids has recently been introduced in several countries. With the use of transcription-mediated amplification, a blood donor was detected who had 90,000 copies of hepatitis B virus (HBV) DNA/mL but no hepatitis B surface antigen (HBsAg) or antibody to hepatitis B core antigen (anti-HBc). One month later, anti-HBc and hepatitis B surface antibody (anti-HBs) appeared; HBV DNA disappeared after 2 months. This study asked why HBsAg was undetectable in this rare case of transient occult HBV infection.

STUDY DESIGN AND METHODS

The HBV DNA in the first sample was cloned and sequenced to identify mutations. The physical nature of the virus was examined by polyethylene glycol precipitation, DNase digestion, density gradient centrifugation, and immunoprecipitation.

RESULTS

Several mutations were found all over the genome, but the HBs antigen loop was unchanged. A stop mutation in the precore region led to loss of hepatitis B e antigen (HBeAg) expression. No HBV DNA–containing immune complexes were present. The plasma did not contain nonencapsidated HBV DNA that could explain the absence of HBsAg. The virus was immune precipitated by antibodies against HBsAg or preS1 antigen. The ratio of HBV to HBsAg subviral particles was estimated to be 1 in less than 20 whereas in overt cases the ratio is 1 in more than 1000.

CONCLUSION

The acute resolving occult HBV infection was caused by an HBeAg-negative variant, which otherwise was almost normal. The negative HBsAg result was probably due to an unusually low production of surplus HBsAg. The absence of the viral immunomodulator HBeAg and the early appearance of anti-HBs suggested a rapid noncytolytic HBsAg-specific T-cell response leading to low expression of HBsAg.

Hydrogenated Microcrystalline Silicon: From Material to Solar Cells

Undoped hydrogenated microcrystalline silicon (νc-Si:H) layers and solar cells have been deposited by plasma-enhanced chemical vapour at low temperature and at different values of VHF plasma power and silane to hydrogen dilution ratios. Transport and defect density measurements on layers suggest that structural properties (e.g. crystallite shape and size) only marginally influence the electronic transport properties. The latter are influenced strongly by the Fermi level, which depends on the oxygen impurity content. Furthermore, they are best described by the quality parameter ν0τ0 (deduced from photoconductivity and ambipolar diffusion length). Cell efficiency correlates better with νoτ0 than with the defect density as determined from subbandgap absorption. Anisotropy of the transport properties in some νc-Si:H is also demonstrated but does not seem to play a major role in νc-Si:H cells deposited at high rates under VHF glow discharge conditions.

Electronic transport and structure of microcrystalline silicon deposited by the VHF-GD technique

Electronic transport parallel and perpendicular to growth direction has been studied in a series of microcrystalline silicon samples obtained by various dilutions of silane in hydrogen. It is clearly shown that the transport properties (dark conductivity, drift mobility, ambipolar diffusion length and photoconductivity) under dark and under illumination conditions are enhanced as the dilution is increased. Furthermore, these films exhibit no degradation upon light-soaking. X-Ray diffraction patterns of the samples confirm that there is a correlation between the amount of crystalline fraction in the samples and the transport properties, as well as a preferential orientation along the growth direction. A similar correlation is found with the shift of the Si-H stretching mode peak of the infrared spectra (IR). Because transport properties have been measured by different techniques (dark conductivity, ambipolar length and photoconductivity in the direction perpendicular to growth direction, drift mobility in the direction parallel to growth direction), no statement can be made about a possible anisotropy in transport, as it would be expected from the columnar shape of the crystallites.

The “Micromorph” Cell: a New Way to High-Efficiency-Low-Temperature Crystalline Silicon Thin-Film Cell Manufacturing?

In the past, microcrystalline silicon (μc-Si:H) has been successfully used as active semiconductor in entirely μc-Si:H p-i-n solar cells and a new type of tandem solar cell, called the “micromorph” cell, was introduced [1]. Micromorph cells consist of an amorphous silicon top cell and a microcrystalline bottom cell. In the paper a micromorph cell with a stable efficiency of 10.7 % (confirmed by ISE Freiburg) is reported.

Among sofar existing crystalline silicon-based solar cell manufacturing techniques, the application of microcrystalline silicon is a new promising way towards implementing thin-film silicon solar cells with a low temperature deposition. Microcrystalline silicon can, indeed, be deposited at temperatures as low as 220°C; hence, the way is here open to use cheap substrates as, e.g. plastic or glass. In the present paper, the development of single and tandem cells containing microcrystalline silicon is reviewed. As stated in previous publications, microcrystalline silicon technique has at present a severe drawback that has yet to be overcome: Its deposition rate for solar-grade material is about 2Å/s; in a more recent case 4.3 Å/s [2] could be obtained. In the present paper, using suitable mixtures of silane, hydrogen and argon, deposition rates of 9.4 Å/s are presented. Thereby the dominating plasma mechanism and the basic properties of resulting layers are described in detail. A first entirely microcrystalline cell deposited at 8.7 Å/s has an efficiency of 3.15%.

Microcrystalline Silicon Solar Cells at Higher Deposition Rates by the VHF-GD

A 7.7 % single junction cell efficiency for an entirely microcrystalline silicon (μc-SiH) device has recently been reported by our group [1]. This was achieved by applying the purifier technique, a technique which is indeed easier to handle than the earlier used “microdoping” approach. The purpose of the present paper is twofold: First to show in detail the impact on device performance when a gas purifier is used; and second to illustrate that the deposition rate of the active, absorbing i-layer can be increased from the former 1.55 Å/s up to 4.3 Å/s while still maintaining reasonable device performances. In the latter case a first n-i-p solar cell structure on an aluminium sheet could be fabricated with an efficiency of 4.9 %.

N-I-P Micromorph Solar Cells on Aluminium Substrates

The first successful deposition of ‘micromorph’ silicon tandem solar cells of the n-i-p-n-i-p configuration is reported. In order to implement the ‘micromorph’ solar cell concept, four key elements had to be prepared: First, the deposition of mid-gap, intrinsic microcrystalline silicon (μc-Si:H) by the 'gas purifier method', second, the amorphous silicon (a-Si:H) n-i-p single junction solar cell, third, the microcrystalline silicon n-i-p single junction solar cell and fourth, the ability of depositing on aluminium sheet substrates.

All the solar cells presented have been deposited on flat aluminium sheets, using a single layer antireflection coating to couple the light into the cell. It is shown, that this antireflection concept- together with a flat substrate- holds for amorphous single junction solar cells, but it reaches its limit with the extended range of spectral response of the ‘micromorph’ cell.

The best initial efficiencies for each category of n-i-p cells on flat substrates were: 8.7% for the amorphous silicon single junction cell, 4.9% for the microcrystalline silicon single junction cell and 9.25% for the ‘micromorph’ tandem cell.

On the Way Towards High Efficiency Thin Film Silicon Solar Cells by the “Micromorph” Concept

Recently the authors have demonstrated that compensated or “midgap” intrinsic hydrogenated microcrystalline silicon (μc-Si:H), as deposited by the Very High Frequency Glow Discharge (VHF-GD) technique, can be used as active layer in p-i-n solar cells. Compared to amorphous silicon (a-Si:H), μc-Si:H was found to have a significantly lower energy bandgap of around 1 eV. The combination of both materials (two absorbers with different gap energies) leads to a “real” tandem cell structure, which was called the “micromorph” cell. Micromorph cells can make better use of the sun's spectrum in contrast to conventional double-stacked a-Si:H / a-Si:H tandems.

The present study will show that the compensation technique (involving boron “microdoping”) used sofar for obtaining midgap μc-Si:H can be replaced by the application of a gas purifier. The use of this gas purifier has a beneficial influence on the transport properties of undoped intrinsic μc-Si:H. By this procedure, increased cell efficiencies in both, single microcrystalline silicon p-i-n as well as micromorph cells could be obtained. In the first case 7.7 % stable, and in the second case 13.1% initial efficiency could be achieved under AM1.5 conditions. Preliminary light-soaking experiments performed on the tandem cells indicate that microcrystalline silicon could contribute to an enhancement of the stable efficiency performance. Micromorph cell manufacturing is fully compatible to a-Si:H technology; however, its deposition rate is still too low. With further increase of the rate, a similar cost reduction potential like in a-Si:H technology can be extrapolated.

Microcrystalline Single-Junction and Micromorph Tandem Thin Film Silicon Solar Cells

Higher open circuit voltages of the microcrystalline silicon bottom cell have a direct impact on the efficiency of the micromorph (μc-Si:H/a-Si:H) tandem cell. In this paper it is shown that open circuit voltages over 500 mV can be achieved leading to gc-Si:H cell efficiencies of 8.5 %. The behaviour of such cells is characterised both by the illuminated and the dark I-V characteristics in function of cell temperature. Microcrystalline cells with Voc-values higher than 500 mV and micromorph tandems possess in general a lower value of the temperature coefficient of the fill factor and thus of the efficiency, when compared to c-Si. Temperature-dependent dark I-V measurements suggest that the dominant recombination mechanism in lgc-Si:H cells is different from that prevailing in a-Si:H solar cells.

The first measurements of soft x-ray flux from ignition scale Hohlraums at the National Ignition Facility using DANTE (invited)

The first 96 and 192 beam vacuum Hohlraum target experiments have been fielded at the National Ignition Facility demonstrating radiation temperatures up to 340 eV and fluxes of 20 TW/sr as viewed by DANTE representing an ∼20 times flux increase over NOVA/Omega scale Hohlraums. The vacuum Hohlraums were irradiated with 2 ns square laser pulses with energies between 150 and 635 kJ. They produced nearly Planckian spectra with about 30±10% more flux than predicted by the preshot radiation hydrodynamic simulations. To validate these results, careful verification of all component calibrations, cable deconvolution, and software analysis routines has been conducted. In addition, a half Hohlraum experiment was conducted using a single 2 ns long axial quad with an irradiance of ∼2×10(15) W/cm(2) for comparison with NIF Early Light experiments completed in 2004. We have also completed a conversion efficiency test using a 128-beam nearly uniformly illuminated gold sphere with intensities kept low (at 1×10(14) W/cm(2) over 5 ns) to avoid sensitivity to modeling uncertainties for nonlocal heat conduction and nonlinear absorption mechanisms, to compare with similar intensity, 3 ns OMEGA sphere results. The 2004 and 2009 NIF half-Hohlraums agreed to 10% in flux, but more importantly, the 2006 OMEGA Au Sphere, the 2009 NIF Au sphere, and the calculated Au conversion efficiency agree to ±5% in flux, which is estimated to be the absolute calibration accuracy of the DANTEs. Hence we conclude that the 30±10% higher than expected radiation fluxes from the 96 and 192 beam vacuum Hohlraums are attributable to differences in physics of the larger Hohlraums.

Endohelminth parasites from salmonids in intensive culture from southern Chile

A total of 228 salmonids (90 Oncorhynchus mykiss, 48 Oncorhynchus kisutch, and 90 Salmo salar) from 8 intensive aquaculture centers in the south of Chile were examined for endohelminths parasites between December 2008 and May 2009. The body cavities of 2 O. mykiss were infected by Diphyllobothrium sp. plerocercoids (prevalence: 6.7%, mean intensity: 1.0, mean abundance: 0.07) from the Lake Tarahuin hatchery on the south of Chiloé Island. Also, tetraphyllidean plerocercoids (prevalence: 3.3%, mean intensity: 1, mean abundance: 0.03) and fourth-stage larvae of Hysterothylacium aduncum (prevalence: 6.7%, mean intensity: 1, mean abundance 0.07) were observed in O. kisutch from a marine hatchery in Chiloé. The occurrences of Diphyllobothrium sp. in a lake and a tetraphyllidean plerocercoid from marine cultured salmonid in Chiloé are reported for first time. No muscular infection by helminths was recorded in the fish examined.

Wastewater use in agriculture: irrigation of sugar cane with effluents from the Cañaveralejo wastewater treatment plant in Cali, Colombia

In Valle del Cauca, south-west Colombia, surface and ground waters are used for sugar cane irrigation at a rate of 100 m3 of water per tonne of sugar produced. In addition large quantities of artificial fertilizers and pesticides are used to grow the crop. Preliminary experiments were undertaken to determine the feasibility of using effluents from the Cañaveralejo primary wastewater treatment plant in Cali. Sugar cane variety CC 8592 was planted in 18 box plots, each 0.5 m2. Six were irrigated with conventional primary effluent, six with chemically enhanced primary effluent and six with groundwater. For each set of six box plots, three contained local soil and three a 50:50 mixture of sand and rice husks. The three irrigation waters were monitored for 12 months, and immediately after harvest the sugar content of the sugar cane juice determined. All physico-chemical quality parameters for the three irrigation waters were lower than the FAO guideline values for irrigation water quality; on the basis of their sodium absorption ratios and electrical conductivity values, both wastewater effluents were in the USDA low-to-medium risk category C2S1. There was no difference in the sugar content of the cane juice irrigated with the three waters. However, the microbiological quality (E. coli and helminth numbers) of the two effluents did not meet the WHO guidelines and therefore additional human exposure control measures are required in order to minimize any resulting adverse health risks to those working in the wastewater-irrigated fields.

Efficacy of hepatitis B virus (HBV) DNA screening and characterization of acute and occult HBV infections among blood donors from Madrid, Spain

BACKGROUND

Screening of blood units for hepatitis B virus (HBV) DNA identifies donations collected during the window period (WP) of the acute infection and may improve viral safety of the blood supply. It also leads to the detection of occult hepatitis B infection (OBI).

STUDY DESIGN AND METHODS

From January 2005 to December 2006, a total of 383,267 blood units were screened for hepatitis B surface antigen (HBsAg) and HBV DNA in two transfusion centers in Madrid, using either individual-donation nucleic acid testing (ID-NAT) or minipool (MP-NAT) of eight donations (MP8). Samples positive for HBV DNA and negative for HBsAg were confirmed by a second molecular test, the viral DNA was quantified, and a genome fragment including the region encoding the major hydrophilic region (MHR) of HBsAg was sequenced.

RESULTS

The overall yield of HBV DNA-positive, HBsAg-negative units was 1 in 21,282 (18 cases), higher when using ID-NAT than MP8-NAT (1:9862 vs. 1:51,011; p < 0.01). Four donations (1/95,817) were collected during the infectious pre-HBsAg WP, one during an early recovery stage, and the remaining 13 (1/29,482) were OBIs, six of whom had no detectable antibody to HBsAg. Low-level Genotype D HBV DNA was detected in all OBI cases; the frequencies of this genotype and MHR amino acid substitutions were significantly higher than reported from unselected Spanish HBsAg carriers. Donors with OBI had normal aminotransferase levels and were significantly older than donors carrying HBsAg.

CONCLUSIONS

Blood donors in the WP and with OBI are not uncommon in Madrid and are detected at a higher frequency with ID-NAT than MP-NAT.

Efficacy of hepatitis B virus (HBV) DNA screening and characterization of acute and occult HBV infections among blood donors from Madrid, Spain

BACKGROUND

Screening of blood units for hepatitis B virus (HBV) DNA identifies donations collected during the window period (WP) of the acute infection and may improve viral safety of the blood supply. It also leads to the detection of occult hepatitis B infection (OBI).

STUDY DESIGN AND METHODS

From January 2005 to December 2006, a total of 383,267 blood units were screened for hepatitis B surface antigen (HBsAg) and HBV DNA in two transfusion centers in Madrid, using either individual-donation nucleic acid testing (ID-NAT) or minipool (MP-NAT) of eight donations (MP8). Samples positive for HBV DNA and negative for HBsAg were confirmed by a second molecular test, the viral DNA was quantified, and a genome fragment including the region encoding the major hydrophilic region (MHR) of HBsAg was sequenced.

RESULTS

The overall yield of HBV DNA-positive, HBsAg-negative units was 1 in 21,282 (18 cases), higher when using ID-NAT than MP8-NAT (1:9862 vs. 1:51,011; p < 0.01). Four donations (1/95,817) were collected during the infectious pre-HBsAg WP, one during an early recovery stage, and the remaining 13 (1/29,482) were OBIs, six of whom had no detectable antibody to HBsAg. Low-level Genotype D HBV DNA was detected in all OBI cases; the frequencies of this genotype and MHR amino acid substitutions were significantly higher than reported from unselected Spanish HBsAg carriers. Donors with OBI had normal aminotransferase levels and were significantly older than donors carrying HBsAg.

CONCLUSIONS

Blood donors in the WP and with OBI are not uncommon in Madrid and are detected at a higher frequency with ID-NAT than MP-NAT.