Search

OBJECTIVES Evaluate the association between maternal social factors and maternal time spent in the NICU for very preterm infants admitted to 4 level III and IV NICUs. METHODS In this prospective observational cohort study, we enrolled mother–infant dyads whose infants were born RESULTS A total of 169 mother–infant dyads were analyzed. Maternal social factors associated with more time spent in the NICU included an annual household income of >$100 000, compared with those with an annual household income of 60 minutes [aOR: 7.85; 95% CI 2.81–21.96]), and the lack of other children in the household, compared with women with other children (aOR: 3.15; 95% CI 1.39–7.11). CONCLUSIONS Maternal time spent in the NICU during a prolonged birth hospitalization of a very preterm infant differed by socioeconomic status, travel time, and presence of other dependents. Strategies to better identify and reduce these disparities to optimize engagement and, subsequently, improve infant health outcomes is needed.

BACKGROUND: Mothers’ engagement with their hospitalized preterm infant(s) is recognized as an important aspect of treatment in neonatal intensive care units (NICU). However, no gold standard exists for measuring maternal engagement, and the various methods used to measure mothers’ time have documented limitations. OBJECTIVES: This study sought to compare three measurement methods of maternal engagement (a 5-item maternal cross-sectional survey, time-use diaries, and electronic health records [EHRs]) to identify whether these methods capture consistent data and patterns in detected differences in measures of engagement. METHODS: Maternal engagement was defined as time spent visiting the infant in the NICU (presence); holding (blanket holding in the mother’s arms or by kangaroo care [KC]); and caregiving (e.g., bathing, changing diapers). The survey estimating daily maternal engagement was administered in two level III NICUs and one level IV NICU at study enrollment, at least 2 weeks after admission. Mothers then completed the daily time-use diaries until infant discharge. Data also were collected from participants’ EHRs, charted by nursing staff. Wilcoxon signed-rank tests were used for pairwise analysis of the three measures for maternal engagement activities. RESULTS: A total of 146 participants had data across all three measurement types and were included in the analysis. In the level III NICUs (n = 101), EHR data showed significantly more time spent with all engagement activities than the diary data. In the level IV data, only differences in time holding were significant when comparing EHR data with survey data, with mothers reporting more time doing KC and less time blanket holding. Comparison of EHR data with diary data showed more time in all activities except KC. DISCUSSION: In most cases, time spent in engagement activities measured in the EHR was higher than in the surveys or time-use diaries. Accuracy of measurements could not be determined due to limitations in data collection, and there is no gold standard for comparison. Nevertheless, findings contribute to ongoing efforts to develop the most valuable and accurate strategies for measuring maternal engagement—a significant predictor of maternal and infant health.

Background To close elliptical excisions, surgeons commonly use the rule of halves which involves initially closing of the middle portion of the wound, followed by closure of the remaining halves. Understanding the forces required for suturing such wounds can aid excisional surgery planning to decrease complications and improve wound healing. Methods Following full thickness excision for removal of skin cancers, back wounds with 3:1 ratio of length-to-width were closed using the rule of halves. The force required to bring the wound edges into contact at the middle portion of the wound was measured, followed by the two bisected halves. Findings The average force to close the center of the wounds averaged 3.7 N and was six times larger than that of the bisected halves. The forces to close the bisected halves were consistently small, and essentially negligible ( Interpretation When planning excisional surgery to avoid complications such as tearing the dermis (cheese wiring), the use of special wound closure techniques (high tension and/or pully sutures, skin support or suture retention devices, etc.) should focus on the center suture only when using the rule of halves, as the remaining sutures require very low forces.

Research suggests maternal engagement in the neonatal intensive care unit (NICU) may positively impact maternal and infant health outcomes. However, the U.S. has lower rates of maternal engagement in the NICU compared to other developed countries. This qualitative study reflects a transdisciplinary research partnership between social work, nursing, and neonatology. Qualitative inquiry explores maternal experiences in the NICU from the perspectives of mothers of preterm infants hospitalized in 2 U.S. NICUs. Results support an ecological systems framework to understanding barriers and facilitators to maternal engagement in the NICU and the utilization of a trauma-informed health care approach in NICU settings.

For patients of reproductive age, treating cancer may come at the price of infertility. Literature regarding fertility preservation recommendations in this population has increased significantly, but this literature too often overlooks or insufficiently considers the relevance of religious preferences. Similarly, practice guidelines do not address the role of religion in the oncofertility discussion. The acceptance of oncofertility practices varies significantly among Christianity, Judaism, and Islam. A patient’s faith-based spirituality or secular morality may enhance his or her interpretation of the meaning of illness and should be incorporated into the informed-consent process. In this article, we describe the role of religious sensitivity in oncofertility care and argue for its importance in such care. We briefly summarize the views and moral reasoning about oncofertility in a few religions commonly encountered in many patient populations today. We recommend that clinicians discuss fertility options early in the decision process and, when relevant, incorporate the patient’s moral and religious preferences into the treatment plan. We encourage providers to be prepared to offer resources to patients who desire moral and spiritual guidance about fertility preservation options. Hospital chaplains should be able to provide such resources.

Background Family-centered care (FCC) in neonatal intensive care units (NICUs) was initiated in 1992 to promote a respectful response to individual family needs and support parental participation in care and decision-making for their infants. Although benefits of FCC have been reported, changes in the maternal experience in the NICU are unknown. Purpose The purpose of this study was to compare mothers' experiences in NICUs where FCC is the standard of care and to compare these with the experiences of mothers 2 decades ago. Methods In this qualitative descriptive design, mothers of infants born under 32 weeks postconceptional age were asked to describe their experiences with their infant's birth and hospitalization. Open-ended probing questions clarified maternal responses. Saturation was reached after 14 interviews. Iterative coding and thematic grouping was used for analysis. Results Common themes that emerged were: (1) visiting; (2) general caregiving; (3) holding; (4) feeding; and (5) maternal ideas for improvement. Findings indicated important improvements in privacy, mother-nurse relationship, ease of visiting, and maternal knowledge and participation in infant caregiving. Implications for practice Mothers suggested improvements such as additional comforts in private rooms, areas in the NICU where they can meet other mothers, and early information on back-transport. Better recognition and response for mothers without adequate social support would provide much needed emotional assistance. Implications for research Future research addressing benefits of webcams, wireless monitors, back-transport, maternity leave, and accommodations for extended visiting for siblings would address other needs mentioned by mothers.

Follicle-stimulating hormone (FSH) regulates follicular growth and stimulates estrogen synthesis in the ovaries. FSH is a heterodimer consisting of an α subunit, also present in luteinizing hormone, and a unique β subunit, which is transcriptionally regulated by gonadotropin-releasing hormone 1 (GNRH). Because most FSH is constitutively secreted, tight transcriptional regulation is critical for maintaining FSH levels within a narrow physiological range. Previously, we reported that GNRH induces FSHβ (Fshb) transcription via induction of the AP-1 transcription factor, a heterodimer of c-FOS and c-JUN. Herein, we identify c-JUN-dimerization protein 2 (JDP2) as a novel repressor of GNRH-mediated Fshb induction. JDP2 exhibited high basal expression and bound the Fshb promoter at an AP-1-binding site in a complex with c-JUN. GNRH treatment induced c-FOS to replace JDP2 as a c-JUN binding partner, forming transcriptionally active AP-1. Subsequently, rapid c-FOS degradation enabled reformation of the JDP2 complex. In vivo studies revealed that JDP2 null male mice have normal reproductive function, as expected from a negative regulator of the FSH hormone. Female JDP2 null mice, however, exhibited early puberty, observed as early vaginal opening, larger litters, and early reproductive senescence. JDP2 null females had increased levels of circulating FSH and higher expression of the Fshb subunit in the pituitary, resulting in elevated serum estrogen and higher numbers of large ovarian follicles. Disruption of JDP2 function therefore appears to cause early cessation of reproductive function, a condition that has been associated with elevated FSH in women.

A 6-year-old boy with Bannayan-Riley-Ruvalcaba syndrome (BRRS) presented to the emergency department with periumbilical abdominal pain for 12 h. A contrast-enhanced abdominal and pelvis CT examination revealed significant interval change in the size and appearance of a previously seen hypoattenuating right mesocolic fatty mass suggestive for lipoma, first observed 5 months prior. This lesion demonstrated new enhancing internal septations, a thickened capsule, interval development of adjacent mesenteric fat stranding and engorgement of the mesenteric vessels. Given the short follow-up interval and acute clinical presentation, imaging findings were suggestive for torsion. We present this case for the unusual imaging findings as well as to highlight the differential diagnosis for abdominal fat containing lesions by imaging in patients with BRRS and other hamartomatous syndromes.

Background Large, prenatally diagnosed sacrococcygeal teratomas (SCTs) present a formidable challenge because of their unpredictable growth and propensity for complications. In our experience, even with aggressive serial imaging, many fetuses have died under a policy of "watchful waiting." We propose "early delivery" as the best option for selected cases of high-risk fetal SCT. Methods The medical charts of all fetuses with SCT followed up at our institution and delivered before 32 weeks of gestation were reviewed for radiologic findings, fetal interventions, delivery information, perinatal inpatient course, and autopsy or discharge report. Results Between 1996 and 2009, excluding those that underwent fetal surgery, 9 patients with fetal SCT were delivered before 32 weeks of gestation. Four had type I tumors, and 5 had type II tumors. Of the 9 fetuses, 4 survived the neonatal period. The only surviving patient delivered before 28 weeks underwent an ex utero intrapartum therapy procedure. Conclusions A significant number of pregnancies complicated by high-risk SCT will manifest signs of fetal or maternal decompensation, or both, between 27 and 32 weeks of gestation. In the absence of fulminant hydrops, preemptive early delivery can be associated with surprisingly good outcomes in appropriately selected fetuses with high-risk SCT.

We study the effect on various properties of varying the intrinsic layer (i-layer) thickness of amorphous/crystalline silicon heterojunction (SHJ) solar cells. Double-side monocrystalline silicon (c-Si) heterojunction solar cells are made using hot-wire chemical vapor deposition on high-lifetime n-type Czochralski wafers. We fabricate a series of SHJ solar cells with the amorphous silicon (a-Si:H) i-layer thickness at the front emitter varying from 3.2 nm (0.8xi) to ~ 96 nm (24xi). Our optimized i-layer thickness is about 4 nm (1xi). Our reference cell (1xi) performance has an efficiency of 17.1% with open-circuit voltage (V oc ) of 684 mV, fill factor (FF) of 76%, and short-circuit current density (J sc ) of 33.1 mA/cm 2 . With an increase of i-layer thickness, V oc changes little, whereas the FF falls significantly after 12 nm (3xi) of i-layer. Transient capacitance measurements are used to probe the effect of the potential barrier at the n-type c-Si/a-Si interface on minority-carrier collection. We show that hole transport through the i-layer is field-driven transport rather than tunneling.

Miho Watanabe, Hiaying Li, Jessica Roybal, Matthew Santore, Antonetta Radu, Jun-Ichiro Jo, Michio Kaneko, Yasuhiko Tabata, and Alan Flake. Tissue Engineering Part A.Apr 2011.1099-1110. http://doi.org/10.1089/ten.tea.2010.0390, Myelomeningocele (MMC) is a common and devastating malformation. As an alternative to fetal surgical repair, tissue engineering has the potential to provide a less invasive approach for tissue coverage applicable at an earlier stage of gestation. We have previously evaluated the use of gelatin hydrogel composites composed of gelatin sponges and sheets as a platform for tissue coverage of the MMC defect in the retinoic acid induced fetal rat model of MMC. In the current study, we compare our previous composite with gelatin microspheres as a scaffold for tissue ingrowth and cellular adhesion within the amniotic fluid environment. We also examine the relative efficacy of various bioactive protein coatings on the adhesion of amniotic fluid cells to the construct within the amniotic cavity. We conclude from this study that gelatin microspheres are as effective as gelatin sponges as a scaffold for cellular ingrowth and amniotic fluid cell adhesion and that collagen type I and fibronectin coatings enhance amniotic fluid cell adhesion to the gelatin-based scaffolds. These findings support the potential for the development of a tissue-engineered injectable scaffold that could be applied by ultrasound-guided injection, much earlier and less invasively than sponge or sheet-based composites. © 2011 Mary Ann Liebert, Inc.

Advances in prenatal diagnosis have led to the prenatal management of a variety of congenital diseases. Although prenatal stem cell and gene therapy await clinical application, they offer tremendous potential for the treatment of many genetic disorders. Normal developmental events in the fetus offer unique biologic advantages for the engraftment of hematopoietic stem cells and efficient gene transfer that are not present after birth. Although barriers to hematopoietic stem cell engraftment exist, progress has been made and preclinical studies are now underway for strategies based on prenatal tolerance induction to facilitate postnatal cellular transplantation. Similarly, in-utero gene therapy shows experimental promise for a host of diseases and proof-in-principle has been demonstrated in murine models, but ethical and safety issues still need to be addressed. Here we review the current status and future potential of prenatal cellular and genetic therapy.

At the present time, the most likely and eminent application of stem cell therapy to the fetus is in utero hematopoietic stem cell transplantation (IUHCT), and this stem cell type will be discussed as a paradigm for all prenatal stem cell therapy. The authors feel that the most likely initial application of IUHCT will use adult HSC derived from bone marrow (BM) or peripheral blood (PB), and will focus this article on this specific approach. The article also reviews the experimental data that support the capacity of IUHCT to induce donor-specific tolerance.

Our research aiming to improve silicon photovoltaic materials and devices extensively utilizes hot-wire chemical vapor deposition (HWCVD). We have recently achieved 18.2% heterojunction silicon solar cells by applying HWCVD a-Si:H front and back contacts to textured p-type silicon wafers. This is the best reported p-wafer heterojunction solar cell by any technique. We have also dramatically improved the quality of HWCVD silicon epitaxy and recently achieved 11 μm of epitaxial growth at a rate of 110 nm/min.

We previously identified FOXL2 as a critical component in FSHβ gene transcription. Here, we show that mice deficient in FOXL2 have lower levels of gonadotropin gene expression and fewer LH- and FSH-containing cells, but the same level of other pituitary hormones compared to wild-type littermates, highlighting a role of FOXL2 in the pituitary gonadotrope. Further, we investigate the function of FOXL2 in the gonadotrope cell and determine which domains of the FOXL2 protein are necessary for induction of FSHβ transcription. There is a stronger induction of FSHβ reporter transcription by truncated FOXL2 proteins, but no induction with the mutant lacking the forkhead domain. Specifically, FOXL2 plays a role in activin induction of FSHβ, functioning in concert with activin-induced SMAD proteins. Activin acts through multiple promoter elements to induce FSHβ expression, some of which bind FOXL2. Each of these FOXL2-binding sites is either juxtaposed or overlapping with a SMAD-binding element. We determined that FOXL2 and SMAD4 proteins form a higher order complex on the most proximal FOXL2 site. Surprisingly, two other sites important for activin induction bind neither SMADs nor FOXL2, suggesting additional factors at work. Furthermore, we show that FOXL2 plays a role in synergistic induction of FSHβ by GnRH and activin through interactions with the cJUN component of the AP1 complex that is necessary for GnRH responsiveness. Collectively, our results demonstrate the necessity of FOXL2 for proper FSH production in mice and implicate FOXL2 in integration of transcription factors at the level of the FSHβ promoter.

Background: Due to anecdotal concerns about adequacy of health professions students’ communication skills, health professions faculty at a private university formed an interprofessional research team. The study was designed to explore whether the use of social networking services (SNS) influenced health care students’ written and oral communication skills. Method: One hundred thirty-two students participated in the study. Communication skills were assessed by using assignments from a health care ethics course required of all students. Use of SNS was measured with an information technology questionnaire. Results: Contrary to expected findings, this exploratory correlation study found no meaningful relationship between the frequency of SNS usage and oral and written communication skills in health professions students. Conclusions: Future studies of SNS would benefit from a younger and more homogeneous study population to assess the use of SNS for learning versus leisure. [ J Nurs Educ. 2015;54(4):207–213.]

We study the differences in hydrogenated amorphous Si (a-Si:H) depositions between Hot-Wire Chemical Vapor Deposition (HWCVD) and Plasma Enhanced Chemical Vapor Deposition (PECVD) for high efficiency a-Si/c-Si heterojunction (HJ) solar cells. In HWCVD, process gases such as silane decompose from the high-temperature hot filament. The resulting deposition is thought to be gentle due to the lack of ion bombardment that may cause damage to c-Si surface. In PECVD, process gases decompose from a high frequency electric field and ion bombardment is expected during the a-Si:H deposition. We found that the initial minority carrier lifetime of a-Si:H passivated high-quality n-type wafer was higher (about a ms) with the HWCVD process, and the final minority carrier lifetime (after 250°C annealing) was higher (over a few ms) with the PECVD process. These findings suggest that the damage from the ion bombarding in PECVD is not as detrimental as we expected; or if there is damage, it can be repaired by the annealing. We also speculate that the lack of further increase of the lifetime after annealing with HWCVD intrinsic a-Si:H layer can be related to the direct substrate heating from the hot filament during the deposition. A high substrate temperature will promote epi-Si growth and drive hydrogen out of the a-Si/c-Si interface to decrease the quality of surface passivation. To reduce the heating effect, a shutter and a low filament temperature are preferred. With the optimized process, we were able to fabricate HJ solar cells with high open circuit voltage of 714 mV and efficiency greater than 19% on an un-textured n-type wafer using the PECVD process, and independently confirm best efficiency of 19.7% on textured n-type wafer with the HWCVD process.

Fetal gene transfer has been studied in various animal models, including rabbits, guinea pigs, cats, dogs, and nonhuman primate; however, the most common model is the rodent, particularly the mouse. There are numerous advantages to mouse models, including a short gestation time of around 20 days, large litter size usually of more than six pups, ease of colony maintenance due to the small physical size, and the relatively low expense of doing so. Moreover, the mouse genome is well defined, there are many transgenic models particularly of human monogenetic disorders, and mouse-specific biological reagents are readily available. One criticism has been that it is difficult to perform procedures on the fetal mouse with suitable accuracy. Over the past decade, accumulation of technical expertise and development of technology such as high-frequency ultrasound have permitted accurate vector delivery to organs and tissues. Here, we describe our experiences of gene transfer to the fetal mouse with and without ultrasound guidance from mid to late gestation. Depending upon the vector type, the route of delivery and the age of the fetus, specific or widespread gene transfer can be achieved, making fetal mice excellent models for exploratory biodistribution studies.

The researchers extensively studied the effects of annealing or thermal history of cell process on the minority carrier lifetimes of FZ n-type c-Si wafers with various i-layer thicknesses from 5 to 60 nm, substrate temperatures from 100 to 350°C, doped layers both p- and n-types, and transparent conducting oxide (TCO). Hot-Wire Chemical Vapor Deposition (HW-CVD) was used to achieve high lifetime, high open circuit voltage (V oc ), and high efficiency in crystalline silicon (c-Si) heterojunction (HJ) solar cells. The minority carrier lifetime with i-layer passivation in as-grown state was found to peak at 200°C substrate temperature. Annealing c-Si with as-grown layers affects the lifetime significantly. The optimized annealing temperature is from 250–350°C. It was also found that the lifetime of c-Si wafers with a very thin i/p passivation decreases significantly when annealed at temperatures higher than 250°C. However, the lifetime of the i/p passivated c-Si wafers is not affected by the p-layer even when the i-layer is as thin as 10 nm. Fourier Transform Infrared Spectroscopy (FTIR) was used to understand the annealing effect. For the c-Si wafers with i/n passivation, the minority carrier lifetime is usually longer than 2 ms and slightly improved by annealing. Minority carrier lifetime greater than 1 ms in a double side HJ structure with i/n and i/p layers can be achieved by controlling thermal history of the cell process. HJ cells were fabricated with an efficiency >18% on n-type wafers without texturing, and an efficiency of 19.2% with texturing.

Fetal gene transfer has been studied in various animal models, including rabbits, guinea pigs, cats, dogs, and nonhuman primate; however, the most common model is the rodent, particularly the mouse. There are numerous advantages to mouse models, including a short gestation time of around 20 days, large litter size usually of more than six pups, ease of colony maintenance due to the small physical size, and the relatively low expense of doing so. Moreover, the mouse genome is well defined, there are many transgenic models particularly of human monogenetic disorders, and mouse-specific biological reagents are readily available. One criticism has been that it is difficult to perform procedures on the fetal mouse with suitable accuracy. Over the past decade, accumulation of technical expertise and development of technology such as high-frequency ultrasound have permitted accurate vector delivery to organs and tissues. Here, we describe our experiences of gene transfer to the fetal mouse with and without ultrasound guidance from mid to late gestation. Depending upon the vector type, the route of delivery and the age of the fetus, specific or widespread gene transfer can be achieved, making fetal mice excellent models for exploratory biodistribution studies.

The ideal gene therapy for metabolical liver disorders would target hepatocytes before the onset of disease and be durable, non-toxic and non-immunogenic. Early gestational gene transfer can achieve such goals. Here, we demonstrate that prenatal gene transfer of human Atp7b reduces liver pathology and improves biochemical markers in Atp7b(-/-) mice, a murine model of Wilson's disease (WD). Following prenatal injection of lentivirus vector containing the human Atp7b gene under the transcriptional control of a liver-specific promoter, the full-length ATP7B was detectable in mouse livers for the entire duration of experiments (20 weeks after birth). In contrast to a marked pathology in non-injected animals, livers from age-matched treated mice consistently demonstrated normal gross and histological morphology. Hepatic copper content was decreased in the majority of treated mice, although remaining copper levels varied. Improvement of hepatic copper metabolism was further apparent from the presence of copper-bound ceruloplasmin in the sera and normalization of the mRNA levels for HMG CoA-reductase. With this approach, the complete loss of copper transport function can be ameliorated, as evident from phenotypical improvement in treated Atp7b(-/-) mice. This study provides proof of principle for in utero gene therapy in WD and other liver-based enzyme deficiencies.

Gene therapy has been applied to murine models of rheumatoid arthritis (RA) using a number of different strategies to downregulate inflammation in synovial joints. However, prolonged joint expression has been problematic. Our laboratory has found that early gestational intravascular injection of lentiviral vector leads to efficient transduction and sustained transgene expression in articular cartilage and synovium. In this study, we show that in utero gene transfer of IL-10 can prevent and decrease pathology in a murine model of RA. Following prenatal injection of lentiviral vector containing murine IL-10 gene, the cytokine was detectable in the serum, and the green fluorescent protein reporter gene was detectable in chondrocytes and synoviocytes of adult mice up to 21 weeks of age. Adult mice that had been treated prenatally were later immunized against type II collagen to induce an autoimmune arthritis. Compared with controls, prenatally treated mice demonstrated delayed onset of arthritis, decreased frequency of arthritis and markedly decreased severity of disease, by both clinical and histological criteria. This effect was directly related to levels of IL-10 expression, but no immunosuppressive effects of the therapy were observed. This study demonstrates proof of principle for the prenatal prevention and amelioration of RA by early gestational gene transfer of the anti-inflammatory cytokine, IL-10.

This paper reports on thin film superconductors of YBaCuO, fabricated via an electrodeposition process from a single electrolyte solution consisting of the nitrate salts of Y(III), Ba(II), and Cu(II) dissolved in an organic solvent dimethyl sulfoxide. Nominal deposition potentials ranging from {minus}2.5 to {minus}4 V (vs. Ag/AgNO{sub 3} reference electrode) are employed. The postannealed electrodeposited films show reproducible zero resistance at about 74 K on Ni, 78 K on MgO, and 91 K on cubic zirconia substrate. The Meissner measurements also support the superconductivity behavior of the thin films. Critical current density of the films deposited on ZrO{sub 2} is 4000 A/cm{sup 2} in zero field at 4 K, and 360 A/cm{sup 2} at 77 K, zero field.

Optical second harmonic generation (SHG) has a long history of being used to selectively characterize surfaces and interface in a variety of materials, including semiconductors. Here, we briefly summarize the physics of SHG and explain why it is a promising characterization technique for photovoltaics (PV), where interfaces and surfaces play critical roles in device performance. We then show experimental results of initial SHG measurements performed on silicon heterojunction solar cells as they are swept through current-voltage curves.

We study amorphous/crystalline silicon heterojunctions (Si HJ) in both p-type and n-type c-Si solar cells under high level of photon injection using concentrated light up to 55 suns. The performance of the cells under intensive light is similar to other types of crystalline Si solar cells. The open circuit voltage (V oc ) increases logarithmically with light intensity for both n-type and p-type base cells and best 760 mV at 48 suns. The best cell efficiency peaks around 10 suns at 19.6% on an untextured p-type Si HJ cell. It represents an 11% increase of the efficiency relative to the one at 1 sun. The decrease of cell efficiency at a higher light intensity is mainly due to the decrease of fill factor (FF). We also found that the FF decreases much quickly in the cell with an n-type wafer compared to a p-type wafer. After more experiments with controlled front finger space, wafer bulk resistivity, and the area of the cells, we conclude that there is a difference in carrier collection for the heterojunction emitters of the n-type and of the p-type c-Si solar cells under intensive illumination.

Background Congenital high airway obstruction syndrome (CHAOS) is caused by complete or near-complete obstruction of the fetal airway. Obstruction sets in motion a sequence of events that can ultimately lead to fetal demise. However, on rare occasions in utero airway decompression occurs, reversing syndromic findings and improving the prognosis. In our relatively large series of CHAOS patients, we have observed a spectrum of clinical severity. The aim of this study was to identify the prenatal characteristics of CHAOS predictive of a milder postnatal course. Methods The medical charts of all fetuses observed at our institution with the diagnosis of CHAOS were reviewed for radiologic findings, delivery information, perinatal course, autopsy or discharge report, and long-term follow-up. Results Between 1996 and 2008, 12 fetuses with CHAOS were identified. Four fetuses had no evidence of hydrops on initial imaging. Of the 8 fetuses displaying hydrops, 3 were terminated, 2 died in utero, and 1 with multiple anomalies died at birth. Six fetuses were delivered via the ex utero intrapartum therapy procedure for attempted salvage, and 5 of the 6 survived the neonatal period including all 4 fetuses without hydrops. Serial prenatal imaging demonstrated less severe signs of CHAOS in 3 fetuses, and in 2 of them, direct laryngoscopy revealed a tiny opening in the airway. All 3 fetuses that showed improvement on serial imaging survived the neonatal period and were discharged home by 2-10 weeks of age. Conclusions Although the natural history of CHAOS is variable, trends in prenatal ultrasound findings are highly predictive of postnatal outcome and are a valuable guide to prenatal counseling.

We fabricated black silicon solar cells with conversion efficiency of 16.8% on p-type single crystal Si wafers with a conventional diffused emitter and Al back-surface field (BSF). We replaced the anti-reflection coating step with a single 3-minute ‘black-silicon’ etch of the bare wafer before processing. The nanoporous black-silicon layer, about 300-nm thick is produced in a 3-minute single-step liquid etch based upon catalysis by Au nano-particles formed in a solution containing HF and H 2 O 2 . Solar cell reflectance is well below 5% at incident wavelengths from 350 to 1000 nm. We present reflectance versus time data during this simple single-step etching. We also characterize cell performance and find that recombination in the black silicon surface layer must still be reduced.

Thin-film superconductors of TlBaCaCuO (TBCCO) and YBaCuO (YBCO) were fabricated via an electrodeposition process. The precursors of the superconducting TBCCO films were codeposited at a constant potential of −4 V onto a silver-coated SrTiO3 substrate. The YBCO precursors also were codeposited but under pulsed-potential conditions (in order to improve the film morphology) and onto a silver-coated MgO substrate. The pulsed-potential cycle consisted of 1 s at −4 V followed by 1 s at −1 V. The post-annealed TBCCO film showed zero resistance at about 102 K and critical current density at 76 K of 20 000 A/cm2 in zero magnetic field and 5000 A/cm2 in a 10 kOe field parallel to the film plane. The post-annealed YBCO film showed zero resistance at approximately 80 K and critical current density of 5160 A/cm2 at 4 K in zero magnetic field.

Minority carrier lifetime and Suns-V oc measurements are well-accepted methods for characterization of solar cell devices. We use these methods, with an instrument from Sinton Consulting, as we fabricate and optimize state-of-the-art all hot-wire chemical vapor deposition (HWCVD) silicon heterojunction (SHJ) devices. For double-sided SHJ devices, lifetime measurements were performed immediately after hydrogenated amorphous silicon (a-Si:H) deposition of the front emitter and back base contacts on a Silicon wafer, and also after indium tin oxide (ITO) deposition of transparent conducting oxide contacts. We report results of minority carrier lifetime measurements for double-sided p-type Si heterojunction devices and compare Suns-V oc results to Light I–V measurements on 1-cm2 solar cell devices measured on an AM1.5 calibrated XT-10 solar simulator.

We prototype an alternative n-type monocrystalline silicon (c-Si) solar cell structure that utilizes an n/i-type hydrogenated amorphous silicon (a-Si:H) front hetero-contact and a back p-n junction formed by alloying aluminum (Al) with the n-type Si wafer. Such a structure combines a conventional high-throughput Al-Si alloying process with excellent front surface passivation provided by a-Si:H. A key process consideration is to preserve the clean c-Si front surface through the high-temperature alloying, so there will be effective a-Si:H passivation. From cell simulations, we estimate a front SRV of 10–50 cm/sec has been achieved in our process. The best prototype 1×1 cm2 cell with planar front surface and single anti-reflection (AR) coating layer has demonstrated a confirmed conversion efficiency of 13.5%, V oc of 604.7 mV, and fill factor (FF) of 79.9%. Processes for further efficiency improvements are described.

We are reporting high performance silicon heterojuncton (SHJ) solar cells fabricated using the hot-wire chemical vapor deposition (HWCVD) technique. On p-type c-Si float-zone wafers, we used an amorphous n/i contact to the top surface and an i/p contact to the back surface to obtain an open circuit voltage (V oc ) of 0.67 V in a 1 cm2 cell with an independent confirmed efficiency of 18.2%. This is the best reported p-type SHJ solar cell, at least by HWCVD. On n-type c-Si float-zone wafers, we used an amorphous (p/i) front emitter and an a-Si:H (i/n) back contact to achieve a Voc of 0.69 V on 1 cm2 cell. We found that proper c-Si surface cleaning prior to the amorphous Si deposition and double-heterojunction is a key to the high Voc. In the heterojunction region, an abrupt interface from c-Si to a-Si:H results in a high Voc; while incorporating a transition to either microcrystalline or epitaxial Si at the c-Si interface results in a low V oc . Lifetime measurement shows that the back surface recombination velocity can be reduced to ~15 cm/s through a-Si:H passivation. Amorphous silicon heterojunction layers on crystalline wafers thus combine low-surface recombination velocity with excellent carrier extraction. The advantages of using HWCVD in comparing with plasma-enhanced CVD are the fast deposition rate and, more important, a wide range of deposition parameters enabling formation of an effective heterojunction with high V oc . Further, the heterojuction cell processing is entirely below 200°C making it one of the few promising low-stress methods for the manufacturing of next generation ultra-thin Si wafer solar cells.

High open-circuit voltage (Voc) silicon heterojunction (SHJ) solar cells are fabricated in double-heterojunction a-Si:H/c-Si/a-Si:H structures using low temperature (p-type c-Si float-zone wafers, we used an amorphous n/i contact to the top surface and an i/p contact to the back surface to obtain a Voc of 667 mV in a 1 cm2 cell with an efficiency of 18.2%. This is the best reported p-type SHJ voltage. In our labs, it improves over the 652 mV cell obtained with a front amorphous n/i heterojunction emitter and a high-temperature alloyed Al back-surface-field contact. On n-type c-Si float-zone wafers, we used an a Si:H (p/i) front emitter and an a-Si:H (i/n) back contact to achieve a Voc of 691 mV on 1 cm2 cell. Though not as high as the 730 mV reported by Sanyo on n-wafers, this is the highest reported Voc for SHJ c-Si cells processed by the HWCVD technique. We found that effective c-Si surface cleaning and a double-heterojunction are keys to obtaining high Voc. Transmission electron microscopy reveals that high Voc cells require an abrupt interface from c-Si to a-Si:H. If the transition from the base wafer to the a-Si:H incorporates either microcrystalline or epitaxial Si at c Si interface, a low Voc will result. Lifetime measurement shows that the back-surface-recombination velocity (BSRV) can be reduced to ~15 cm/s through a-Si:H passivation. Amorphous silicon heterojunction layers on crystalline wafers thus combine low-surface recombination velocity with excellent carrier extraction.

We report progresses in the development of silicon heterojunction (SHJ) solar cells by hot-wire chemical vapor deposition (HWCVD). A confirmed 18.2% efficiency on a p-type textured wafer has been achieved based on improvements in surface passivation by a-Si:H emitter and back contact as well as in fill factor. The primary objective of high open-circuit voltage (Voc) is achieved by front a-Si:H/c-Si heterojunction optimization, by replacing a conventional Al-alloyed or P-diffused back-surface field with a back c-Si/a-Si:H heterojunction, and by maintaining excellent surface passivation on textured silicon wafers. We first obtain a Voc of 652 mV with a front a-Si:H(n/i) heterojunction emitter on p-type solar cells with an Al back-surface-field (BSF) contact. The high-temperature Al-BSF is then successfully replaced by low-temperature HWCVD-deposited a-Si:H(i/p) layers as the back contact. Lifetime measurement shows the surface recombination velocity (SRV) is reduced to ~15 cm/sec. A higher Voc of 676 mV is obtained with an a-Si:H(n/i) front-emitter and a-Si:H(i/p) back-contact double-heterojunction SHJ solar cell structure, indicating superior back-surface passivation of the textured p-wafer. On n-type silicon wafers, we use an a-Si:H(p/i) front emitter and an a-Si:H(i/n) back contact, to achieve a Voc of 711 mV, the highest voltage obtained by the HWCVD technique so far. Good fill factors are also obtained using the amorphous-phase materials as the back contacts. S-shaped I-V curves are observed if doping cross-contamination are present among different a-Si:H layers or doping level is not enough in the TCO-contacting p-type a-Si:H layer

In this paper, we present the electromagnetic and structural design of a low-/spl beta/ superconducting spoke resonator for a beam-test in the Low Energy Demonstration Accelerator (LEDA). This test is part of the Advanced Accelerator Applications (AAA) project. Recently, the use of superconducting resonators for energies greater than 6.7 MeV has been approved. The beam test will use the lowest-/spl beta/ resonator from this accelerator design. The choices of the cavity dimensions are driven by its use immediately downstream of the LEDA Radio-Frequency Quadrupole (RFQ). The frequency is 350 MHz. The length corresponds to a geometric /spl beta/ (/spl beta//sub g/) of 0.175. Our design approach has been to carry out an integrated RF and mechanical design from the start. The final cavity is well understood in terms of RF and mechanical properties. The RF properties, like Q, R/Q, peak surface fields and acceleration efficiency are very reasonable for such a low-/spl beta/ structure. The design also includes power coupler, vacuum and pick-up ports and their influences. The mechanical design added tuning sensitivities, tuning forces, stiffening schemes and the understanding of stresses under various load conditions.

The Accelerator Driven Test Facility (ADTF) is being developed as a reactor concepts test bed for transmutation of nuclear waste. A 13.3 mA continuous-wave (CW) proton beam will be accelerated to 600 MeV and impinged on a spallation target. The subsequent neutron shower is used to create a nuclear reaction within a subcritical assembly of waste material that reduces the waste half-life from the order of 10 5 years to 10 2 years. Additionally, significant energy is produced that can be used to generate electrical power. The ADTF proton accelerator consists of room-temperature (RT) structures that accelerate the beam to 6.7-MeV and superconducting (SC) elements that boost the beam's energy to 600-MeV. Traditional SC elliptical cavities experience structural difficulties at low energies due to their geometry. Therefore, stiff-structured SC spoke cavities have been adopted for the energy range between 6.7 and 109 MeV. Elliptical cavities are used at the higher energies. This paper describes a multi-spoke-cavity cryomodule concept for ADTF.

Efficient crystalline silicon heterojunction solar cells are fabricated on p-type wafers using amorphous silicon emitter and back contact layers. The independently confirmed AM1.5 conversion efficiencies are 19.3% on a float-zone wafer and 18.8% on a Czochralski wafer; conversion efficiencies show no significant light-induced degradation. The best open-circuit voltage is above 700 mV. Surface cleaning and passivation play important roles in heterojunction solar cell performance.

Thin film superconductors of Pb-Bi-Sr-Ca-Cu-O and Y-Ba-Cu-O are fabricated via an electrodeposition process. Nominal deposition potentials ranging from −2.5 V to −4 V (versus Ag/AgNO3, reference electrode) are employed. The post-annealed electrodeposited Pb-Bi-Sr-Ca-Cu-O films show reproducible zero resistance at about 62K on Al2O3 or MgO substrates. The post-annealed electrodeposited Y-Ba-Cu-O films show reproducible zero resistance at about 74K on Ni, 78K on MgO and 91K on ZrO substrate. The Meissner measurements also support the superconductivity behavior of the thin films. The critical current density of the Pb-Bi-Sr-Ca-Cu-O films deposited on MgO is about 500 A/cm2 in zero field at 4K. The critical current density of the Y-Ba-Cu-O films deposited on ZrO is 4×103 A/cm2 in zero field at 4K, and 360 A/cm2 at 77K, in zero field.

The standard diagnostic for determining the superconducting transition temperatures of thin films is the resistivity-temperature (R-T) measurement. These resistivity measurements are made as a function of temperature at constant current in a four-point probe configuration. The R-T measurements show that the films contain superconducting paths but are not very sensitive to the uniformity of the superconducting phase.

A radio-frequency quadrupole (RFQ) structure operating at low frequency has been developed for possible use in accelerators for heavy ion fusion or Tokamak plasma heating. The structure uses a series of shunt spiral inductors placed periodically along the electrodes of an electric quadrupole to achieve resonance at the desired frequency. A 1.2-m-long model has been constructed for low-power testing. The model resonates near 12 MHz and has radial dimensions that are reduced by a factor of 15 compared to the commonly used four-vane resonator.

Very strong capacitance‐voltage dispersive effects are observed in mercury/indium phosphide Schottky diodes. These effects are related to a partially compensated region at the surface for which the Debye length is relatively large. The small‐signal capacitance is indicative of a critical dielectric relaxation time exceeding the period of the ac probe. This effect may be used to characterize the majority‐carrier profile in lightly doped or low mobility semiconductors.