Early embryo-maternal communication in the oviduct: A review.

An intact embryo-maternal communication is critical for the establishment of a successful pregnancy. To date, a huge number of studies have been performed describing the complex process of embryo-maternal signaling within the uterus. However, recent studies indicate that the early embryo communicates with the oviductal cells shortly after fertilizationand that this is important for the successful establishment of pregnancy. Only if the early embryo is capable to signal the mother within a precise timeframe and to garner a response, will the embryo be able to survive and reach the uterus. This review will give an overview of all the experimental designs which have investigated embryo-maternal interaction in the oviduct. In addition to that, it will provide a comprehensive analysis of the findings to date elucidating the morphological and molecular changes in the oviduct which are induced by the presence of the early embryo highlighting how the tubal responses affect embryo development and survival.

How do elevated levels of testosterone affect the function of the human fallopian tube and fertility?-New insights.

Excess testosterone levels affect up to 20% of the female population worldwide and are a key component in the pathogenesis of polycystic ovary syndrome. However, little is known about how excess testosterone affects the function of the human fallopian tube-the site of gamete transport, fertilization, and early embryogenesis. Therefore, this study aimed to characterize alterations caused by long-term exposure to male testosterone levels. For this purpose, the Fallopian tubes of nine female-to-male transsexuals, who had been undergoing testosterone treatment for 1-3 years, were compared with the tubes of 19 cycling patients. In the ampulla, testosterone treatment resulted in extensive luminal accumulations of secretions and cell debris which caused ciliary clumping and luminal blockage. Additionally, the percentage of ciliated cells in the ampulla was significantly increased. Transsexual patients, who had had sexual intercourse before surgery, showed spermatozoa trapped in mucus. Finally, in the isthmus complete luminal collapse occurred. Our results imply that fertility in women with elevated levels of testosterone is altered by tubal luminal obstruction resulting in impaired gamete transport and survival.

Synthesis and Spectroscopy of Silver-Doped PbSe Quantum Dots.

Electronic impurity doping of bulk semiconductors is an essential component of semiconductor science and technology. Yet there are only a handful of studies demonstrating control of electronic impurities in semiconductor nanocrystals. Here, we studied electronic impurity doping of colloidal PbSe quantum dots (QDs) using a postsynthetic cation exchange reaction in which Pb is exchanged for Ag. We found that varying the concentration of dopants exposed to the as-synthesized PbSe QDs controls the extent of exchange. The electronic impurity doped QDs exhibit the fundamental spectroscopic signatures associated with injecting a free charge carrier into a QD under equilibrium conditions, including a bleach of the first exciton transition and the appearance of a quantum-confined, low-energy intraband absorption feature. Photoelectron spectroscopy confirms that Ag acts as a p-type dopant for PbSe QDs and infrared spectroscopy is consistent with k·p calculations of the size-dependent intraband transition energy. We find that to bleach the first exciton transition by an average of 1 carrier per QD requires that approximately 10% of the Pb be replaced by Ag. We hypothesize that the majority of incorporated Ag remains at the QD surface and does not interact with the core electronic states of the QD. Instead, the excess Ag at the surface promotes the incorporation of <1% Ag into the QD core where it causes p-type doping behavior.

Synthesis and spectroscopy of PbSe fused quantum-dot dimers.

We report the synthesis and characterization of Pb-chalcogenide fused quantum-dot (QD) dimer structures. The resulting QD dimers range in length from 6 to 16 nm and are produced by oriented attachment of single QD monomers with diameters of 3.1-7.8 nm. QD monomers with diameters exceeding about 5 nm appear to have the greatest affinity for QD dimer formation and, therefore, gave the greatest yields of fused structures. We find a new absorption feature in the first exciton QD dimer spectra and assign this to a splitting of the 8-fold degenerate 1S-level. The dimer splitting increases from 50 to 140 meV with decrease of the QD-monomer size, and we present a mechanism that accounts for this splitting. We also demonstrate the possibility of fusing two QDs with different sizes into a heterostructure.

Comparing multiple exciton generation in quantum dots to impact ionization in bulk semiconductors: implications for enhancement of solar energy conversion.

Multiple exciton generation (MEG) in quantum dots (QDs) and impact ionization (II) in bulk semiconductors are processes that describe producing more than one electron-hole pair per absorbed photon. We derive expressions for the proper way to compare MEG in QDs with II in bulk semiconductors and argue that there are important differences in the photophysics between bulk semiconductors and QDs. Our analysis demonstrates that the fundamental unit of energy required to produce each electron-hole pair in a given QD is the band gap energy. We find that the efficiency of the multiplication process increases by at least 2 in PbSe QDs compared to bulk PbSe, while the competition between cooling and multiplication favors multiplication by a factor of 3 in QDs. We also demonstrate that power conversion efficiencies in QD solar cells exhibiting MEG can greatly exceed conversion efficiencies of their bulk counterparts, especially if the MEG threshold energy can be reduced toward twice the QD band gap energy, which requires a further increase in the MEG efficiency. Finally, we discuss the research challenges associated with achieving the maximum benefit of MEG in solar energy conversion since we show the threshold and efficiency are mathematically related.

"Could you give us an idea on what we are all doing here?" the Patient Voice in Cancer Research (PVCR) starting the journey of involvement in Ireland.

BACKGROUND: Involving patients and their carers in research has become more common, as funders demand evidence of involvement. The 'Patient Voice in Cancer Research' (PVCR) is an initiative led by University College Dublin (UCD) in Ireland. It encourages and enables people affected by cancer, and their families to become involved in shaping and informing the future of cancer research across the island of Ireland. Its aim is to identify the questions and needs that matter most to (i) people living with a cancer diagnosis, and (ii) those most likely to improve the relevance of cancer research. The initiative commenced in April 2016. METHODS: This paper presents a reflective case study of our journey thus far. We outline three key stages of the initiative and share what we have learnt. At the core of PVCR, is a focus on building long-term relationships. RESULTS: We have developed over time an inclusive initiative that is built on trust and respect for everyone's contributions. This work is grounded on collegiality, mixed with a good sense of humour and friendship. CONCLUSION: The development of PVCR has taken time and investment. The benefits and impact of undertaking this work have been immensely rewarding and now require significant focus as we enhance cancer research across the island of Ireland.

Nurse-physician collaboration in an acute care community hospital.

Despite the evidence from the literature of the benefits of collaboration, a collaborative practice model in the acute-care setting remains the exception rather than the dominant practice. The purpose of this study was to evaluate attitudes toward collaboration among nurses and physicians practicing in an acute care community hospital. The sample included 118 nurses and 53 physicians. Background variables of gender, age, education, experience, practice setting, cultural background, and time to interact were examined to determine if they influenced attitudes towards collaboration. The results indicated that both physicians and nurses expressed positive attitudes towards collaboration but that there was a significant difference on two of the underlying factors: shared education and physician authority. The study may serve as a baseline for future research, specifically focused on interventions to enhance collaboration.

Structural, optical, and electrical properties of PbSe nanocrystal solids treated thermally or with simple amines.

We describe the structural, optical, and electrical properties of films of spin-cast, oleate-capped PbSe nanocrystals that are treated thermally or chemically in solutions of hydrazine, methylamine, or pyridine to produce electronically coupled nanocrystal solids. Postdeposition heat treatments trigger nanocrystal sintering at approximately 200 degrees C, before a substantial fraction of the oleate capping group evaporates or pyrolyzes. The sintered nanocrystal films have a large hole density and are highly conductive. Most of the amine treatments preserve the size of the nanocrystals and remove much of the oleate, decreasing the separation between nanocrystals and yielding conductive films. X-ray scattering, X-ray photoelectron and optical spectroscopy, electron microscopy, and field-effect transistor electrical measurements are used to compare the impact of these chemical treatments. We find that the concentration of amines adsorbed to the NC films is very low in all cases. Treatments in hydrazine in acetonitrile remove only 2-7% of the oleate yet result in high-mobility n-type transistors. In contrast, ethanol-based hydrazine treatments remove 85-90% of the original oleate load. Treatments in pure ethanol strip 20% of the oleate and create conductive p-type transistors. Methylamine- and pyridine-treated films are also p-type. These chemically treated films oxidize rapidly in air to yield, after short air exposures, highly conductive p-type nanocrystal solids. Our results aid in the rational development of solar cells based on colloidal nanocrystal films.

Covalently Bound Nitroxyl Radicals in an Organic Framework.

A series of covalent organic framework (COF) structures is synthesized that possesses a tunable density of covalently bound nitroxyl radicals within the COF pores. The highest density of organic radicals produces an electron paramagnetic resonance (EPR) signal that suggests the majority of radicals strongly interact with other radicals, whereas for smaller loadings the EPR signals indicate the radicals are primarily isolated but with restricted motion. The dielectric loss as determined from microwave absorption of the framework structures compared with an amorphous control suggests that free motion of the radicals is inhibited when more than 25% of available sites are occupied. The ability to tune the mode of radical interactions and the subsequent effect on redox, electrical, and optical characteristics in a porous framework may lead to a class of structures with properties ideal for photoelectrochemistry or energy storage.

Close Packing of Nitroxide Radicals in Stable Organic Radical Polymeric Materials.

The relationship between the polymer network and electronic transport properties for stable radical polymeric materials has come under investigation owing to their potential application in electronic devices. For the radical polymer poly(2,2,6,6-tetramethylpiperidine-4-yl-1-oxyl methacrylate), it is unclear whether the radical packing is optimal for charge transport partially because the relationship between radical packing and molecular structure is not well-understood. Using the paramagnetic nitroxide radical as a probe of the polymer and synthetic techniques to control the radical concentration on the methyl methacrylate backbone, we investigate the dependence of radical concentration on molecular structure. The electron paramagnetic resonance data indicate that radicals in the PTMA assume a closest approach distance to each other when more than 60% of the backbone is populated with radical pendant groups. Below 60% coverage, the polymer rearranges to accommodate larger radical-radical spacing. These findings are consistent with theoretical calculations and help explain some experimentally determined electron-transport properties.

Quenching of the perylene fluorophore by stable nitroxide radical-containing macromolecules.

Stable nitroxide radical bearing organic polymer materials are attracting much attention for their application as next generation energy storage materials. A greater understanding of the inherent charge transfer mechanisms in such systems will ultimately be paramount to further advancements in the understanding of both intrafilm and interfacial ion- and electron-transfer reactions. This work is focused on advancing the fundamental understanding of these dynamic charge transfer properties by exploiting the fact that these species are efficient fluorescence quenchers. We systematically incorporated fluorescent perylene dyes into solutions containing the 2,2,6,6-tetramethylpiperidine-N-oxyl (TEMPO) radical and controlled their interaction by binding the TEMPO moiety into macromolecules with varying morphologies (e.g., chain length, density of radical pendant groups). In the case of the model compound, 4-oxo-TEMPO, quenching of the perylene excited state was found to be dominated by a dynamic (collisional) process, with a contribution from an apparent static process that is described by an ∼2 nm quenching sphere of action. When we incorporated the TEMPO unit into a macromolecule, the quenching behavior was altered significantly. The results can be described by using two models: (A) a collisional quenching process that becomes less efficient, presumably due to a reduction in the diffusion constant of the quenching entity, with a quenching sphere of action similar to 4-oxo-TEMPO or (B) a collisional quenching process that becomes more efficient as the radius of interaction grows larger with increasing oligomer length. This is the first study that definitively illustrates that fluorophore quenching by a polymer system cannot be explained using merely a classical Stern-Volmer approach but rather necessitates a more complex model.

Malignant catatonia mimicking pheochromocytoma.

Malignant catatonia is an unusual and highly fatal neuropsychiatric condition which can present with clinical and biochemical manifestations similar to those of pheochromocytoma. Differentiating between the two diseases is essential as management options greatly diverge. We describe a case of malignant catatonia in a 20-year-old male who presented with concurrent psychotic symptoms and autonomic instability, with markedly increased 24-hour urinary levels of norepinephrine at 1752 nmol/day (normal, 89-470 nmol/day), epinephrine at 1045 nmol/day (normal, <160 nmol/day), and dopamine at 7.9 µ mol/day (normal, 0.4-3.3 µ mol/day). The patient was treated with multiple sessions of electroconvulsive therapy, which led to complete clinical resolution. Repeat urine collections within weeks of this presenting event revealed normalization or near normalization of his catecholamine and metanephrine levels. Malignant catatonia should be considered in the differential diagnosis of the hypercatecholamine state, particularly in a patient who also exhibits concurrent catatonic features.

The subtle chemistry of colloidal, quantum-confined semiconductor nanostructures.

Nanoscale colloidal semiconductor structures with at least one dimension small enough to experience quantum confinement effects have captured the imagination and attention of scientists interested in controlling various chemical and photophysical processes. Aside from having desirable quantum confinement properties, colloidal nanocrystals are attractive because they are often synthesized in low-temperature, low-cost, and potentially scalable manners using simple benchtop reaction baths. Considerable progress in producing a variety of shapes, compositions, and complex structures has been achieved. However, there are challenges to overcome in order for these novel materials to reach their full potential and become new drivers for commercial applications. The final shape, composition, nanocrystal-ligand structure, and size can depend on a delicate interplay of precursors, surface ligands, and other compounds that may or may not participate in the reaction. In this Perspective, we discuss current efforts toward better understanding how the reactivity of the reagents can be used to produce unique and complex nanostructures.

Control of PbSe quantum dot surface chemistry and photophysics using an alkylselenide ligand.

We have synthesized alkylselenide reagents to replace the native oleate ligand on PbSe quantum dots (QDs) in order to investigate the effect of surface modification on their stoichiometry, photophysics, and air stability. The alkylselenide reagent removes all of the oleate on the QD surface and results in Se addition; however, complete Se enrichment does not occur, achieving a 53% decrease in the amount of excess Pb for 2 nm diameter QDs and a 23% decrease for 10 nm QDs. Our analysis suggests that the Se ligand preferentially binds to the {111} faces, which are more prevalent in smaller QDs. We find that attachment of the alkylselenide ligand to the QD surface enhances oxidative resistance, likely resulting from a more stable bond between surface Pb atoms and the alkylselenide ligand compared to Pb-oleate. However, binding of the alkylselenide ligand produces a separate nonradiative relaxation route that partially quenches PL, suggesting the formation of a dark hole-trap.

Emission Quenching in PbSe Quantum Dot Arrays by Short-Term Air Exposure.

Clear evidence for two emitting states in PbSe nanocrystals (NCs) has been observed. The flow of population between these two states as temperature increases is interrupted by the presence of nonradiative trap states correlated with the exposure of the NC film to air. Quenching of the higher-energy emission begins after only seconds of exposure, with the effect saturating after several days. Unlike short-term oxygen-related effects in solution, the emission quenching appears to be irreversible, signaling a distinction between surface reactivity in NCs in films and that in solution. The origin of the two emissive centers and the impact of trapping on other NC film properties (e.g., electron/hole mobilities) remain important issues to be resolved.

Spinal column and spinal cord injuries in mountain bikers: a 13-year review.

BACKGROUND: Multiple studies have described in general the injuries associated with mountain biking, and detailed accounts of spine injuries sustained in hockey, gymnastics, skiing, snowboarding, rugby, and paragliding have previously been published. However, no large-scale detailed assessment of mountain biking associated spinal fractures and spinal cord injuries has previously been published. PURPOSE: This study was undertaken to describe the patient demographics, injuries, mechanisms, treatments, outcomes, and resource requirements associated with spine injuries sustained while mountain biking. STUDY DESIGN: Case series; Level of evidence, 4. METHODS: Patients who were injured while mountain biking, and who were seen at a provincial spine referral center between 1995 and 2007 inclusive, with spinal cord injuries and/or spine fracture were included. A chart review was performed to obtain demographic data, and details of the injury, treatment, outcome, and resource requirements. RESULTS: A total of 102 men and 5 women were identified for inclusion. The mean age at injury was 32.7 years (95% confidence interval 30.6, 35.0). Seventy-nine patients (73.8%) sustained cervical injuries, while the remainder sustained thoracic or lumbar injuries. Forty-three patients (40.2%) sustained a spinal cord injury. Of those with cord injuries, 18 (41.9%) were American Spinal Injury Association (ASIA) A, 5 (11.6%) were ASIA B, 10 (23.3%) ASIA C, and 10 (23.3%) ASIA D. Sixty-seven patients (62.6%) required surgical treatment. The mean length of stay in an acute hospital bed was 16.9 days (95% confidence interval 13.1, 30.0). Thirty-three patients (30.8%) required intensive care unit attention, and 31 patients (29.0%) required inpatient rehabilitation. Of the 43 patients (40.2%) seen with spinal cord injuries, 14 (32.5%) improved by 1 ASIA category, and 1 (2.3%) improved by 2 ASIA categories. Two patients remained ventilator-dependent at discharge. CONCLUSION: Spine fractures and spinal cord injuries caused by mountain biking accidents typically affect young, male, recreational riders. The medical, personal, and societal costs of these injuries are high. Injury prevention should remain a primary goal, and further research is necessary to explore the utility of educational programs, and the effect of helmets and other protective gear on spine injuries sustained while mountain biking.

Comparison of wheelchair wheels in terms of vibration and spasticity in people with spinal cord injury.

A wheelchair undergoes vibrations while traveling over obstacles and uneven surfaces, resulting in whole body vibration of the person sitting in the wheelchair. According to clinicians, people with spinal cord injury (SCI) report that vibration evokes spasticity. The relatively new Spinergy wheelchair wheels (Spinergy, Inc; San Diego, California) are claimed to absorb more road shock then conventional steel-spoked wheelchair wheels. If this claim is true, this wheel might also reduce spasticity in people with SCI. We hypothesized that Spinergy wheels would absorb vibration, reduce perceived spasticity, and improve comfort in individuals with SCI more than standard steel-spoked wheels. To test this hypothesis, 22 nondisabled subjects performed a passive ramp test so that we could more closely examine the dampening characteristics of the Spinergy versus traditional wheels. Furthermore, 13 subjects with SCI performed an obstacle test with both wheel types. Vibrations were measured with accelerometers, and spasticity and comfort were assessed with subject-reported visual analog scales. The results of the study showed that, within the current experimental setup, the Spinergy wheels neither reduced vibration or perceived spasticity nor improved comfort in people with SCI more than the conventional steel-spoked wheels.

A comparison of spinergy versus standard steel-spoke wheelchair wheels.

OBJECTIVES: To compare the energy efficiency of straight-line wheeling using Spinergy wheels as compared with standard steel-spoke wheels, and to assess the 2 wheels in terms of user comfort and wheeling preference during a wheeling course with multiple turns and surfaces. DESIGN: Nonblinded randomized crossover trial. SETTING: Rehabilitation center. PARTICIPANTS: Twenty persons with paraplegia (neurologic level T6 and below). INTERVENTION: Wheeling a straight line and obstacle course with Spinergy or standard spoke wheelchair wheels. MAIN OUTCOME MEASURES: Velocity and Physiological Cost Index (PCI) while wheeling over ground at a self-selected pace, and the User Preference Questionnaire after wheeling an obstacle course, using Spinergy or standard spoke wheelchair wheels. RESULTS: There was no significant difference in wheeling energy efficiency between the Spinergy and the steel-spoke wheels as measured by PCI ( P =.975). When rated for overall comfort, the Spinergy wheels were preferred over steel-spoke wheels ( P =.002). CONCLUSIONS: Spinergy wheels provided a more comfortable ride, but did not differ from standard steel-spoked wheels in terms of energy efficiency. The increased comfort may have important implications in patient management of pain and spasticity.