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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.

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.

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.