Thermoresponsive Pickering Emulsions Stabilized by Silica Nanoparticles in Combination with Alkyl Polyoxyethylene Ether Nonionic Surfactant

We put forward a simple protocol to prepare thermoresponsive Pickering emulsions. Using hydrophilic silica nanoparticles in combination with a low concentration of alkyl polyoxyethylene monododecyl ether (C₁₂E_n) nonionic surfactant as emulsifier, oil-in-water (o/w) emulsions can be obtained, which are stable at room temperature but demulsified at elevated temperature. The stabilization can be restored once the separated mixture is cooled and rehomogenized, and this stabilization-destabilization behavior can be cycled many times. It is found that the adsorption of nonionic surfactant at the silica nanoparticle-water interface via hydrogen bonding between the oxygen atoms in the polyoxyethylene headgroup and the SiOH groups on particle surfaces at low temperature is responsible for the in situ hydrophobization of the particles rendering them surface-active. Dehydrophobization can be achieved at elevated temperature due to weakening or loss of this hydrogen bonding. The time required for demulsification decreases with increasing temperature, and the temperature interval between stabilization and destabilization of the emulsions is affected by the surfactant headgroup length. Experimental evidence including microscopy, adsorption isotherms, and three-phase contact angles is provided to support the mechanism.

Contribution of the PDL to Osteotomy Repair and Implant Osseointegration

Our objective was to clarify the fate of the periodontal ligament (PDL) retained in the socket after tooth extraction, then determine if this tissue contributed to the osseointegration of "immediate" implants placed in these fresh extraction sockets. Mice underwent maxillary first molar extraction, the residual PDL was removed by an osteotomy, and titanium implants were placed. The osteotomy was created in such a way that the palatal surface was devoid of PDL remnants while the buccal, mesial, and distal surfaces retained PDL fibers. At multiple time points after surgery, tissues were analyzed using a battery of molecular, cellular, and histomorphometrical assays. We found that PDL remnants mineralized and directly contributed to new bone formation in the extraction site. Compared with regions of an extraction site where the PDL was removed by osteotomy, regions that retained PDL fibers had produced significantly more new bone. Around immediate implants, the retained PDL remnants directly contributed to new bone formation and osseointegration. Thus, we conclude that PDL remnants are inherently osteogenic, and if the tissue is healthy, it is reasonable to conclude that curetting out an extraction socket prior to immediate implant placement should be avoided. This recommendation aligns with contemporary trends toward minimally invasive surgical manipulations of the extraction socket prior to immediate implant placement.

A Census of Actively Licensed Physicians in the United States, 2016

An accurate understanding of the demographic and state medical licensure characteristics of physicians in the United States is critical for health care workforce planning. Overall changes in the nation's population demographics, state and federal medical regulatory policies and dynamics surrounding the ongoing health care reform debate further highlight the need to have an up-to-date census of actively licensed physicians across all medical specialties.

This article uses data received by the Federation of State Medical Boards (FSMB) from the nation's state medical and osteopathic licensing boards to report and summarize key features of actively licensed physicians in the United States and the District of Columbia. Our biennial census, current through the end of 2016, identifies a total of 953,695 actively licensed allopathic and osteopathic physicians serving a national population of 323 million people. This represents a net physician-increase of 12% from the 2010 census. From 2010 to 2016, the actively licensed U.S. physician-to-population ratio increased from 277 physicians per 100,000-population to 295 physicians per 100,000-population. Females now make up one-third of all licensed physicians, with osteopathic physicians and Caribbean medical graduates continuing to demonstrate substantial increases in both their absolute numbers and as a percentage of all actively licensed physicians from the 2010 to 2016 time period.

CO2/N2 triggered switchable Pickering emulsions stabilized by alumina nanoparticles in combination with a conventional anionic surfactant

Switchable n-decane-in-water Pickering emulsions were prepared using positively charged alumina nanoparticles in combination with a trace amount of the anionic surfactant sodium dodecyl sulfate (SDS) and equal moles of a CO₂/N₂ switchable surfactant.

Intergenerational Exchange of Resources and Elderly Support in Rural China

This study examines how parental investments on children affect elderly support, and how this effect is contingent on emotional closeness or parental authority. Data collected from 770 elderly parents residing in rural China were analyzed. We gathered dichotomous data for (a) whether parents invested on their children via financial or instrumental means (i.e., parental investments) and (b) whether parents reported closeness to their children (i.e., emotional closeness) and whether children respected them (i.e., parental authority). We examined the relation between these variables and children's elderly support (financial, instrumental, and emotional). We tested models in two ways, one examining the direct effect of investments, and another testing the interactions between investments and closeness or authority. We first found that investments were not directly associated with elderly support, although the closeness and authority were. Additionally, the association between investments and support was found within parents who reported authority or closeness with their children.

Mechanically-sensitive hydrogels formed from β-cyclodextrin and an anionic surfactant containing a biphenyl group

Hydrogels are important soft materials with intriguing properties. By taking advantage of the host-guest interactions and multiple molecular interactions, it is expected that novel hydrogel systems can be formed. This strategy has been implemented here, transparent hydrogels were formed by using a newly-synthesized anionic surfactant, sodium 2-(4-phenylphenoxy)dodecanoate (C12biphNa), and β-cyclodextrin (β-CD) in different proportions and their properties were investigated. Gelation of water occurs at extremely low surfactant concentrations (5 mM for a 1:3 C12biphNa: β-CD system), and a single C12biphNa with its associated β-CDs can trap about 11,000 water molecules on average. In addition, the systems are fragile to mechanical stimulus and thus show mechanical sensitivity. Cryo-TEM reveals that the hydrogels have a microstructure consisting of rigid nanowire-like aggregates (with cross-sectional diameters of about 7-8 nm) locally distributed in a parallel manner in solution. These microstructural features are responsible for the peculiar properties of the hydrogel systems presented. The inclusion complexes formed by C12biphNa and β-CD were investigated using (1)H NMR and 2D nuclear overhauser effect spectroscopy and their aggregation state was proposed. This work enriches the connotation of nonamphiphilic self-assembly and provides inspiration for constructing new functional soft materials.

The revascularization and follicular survival of mouse ovarian grafts treated with FSH during cryopreservation by vitrification

BACKGROUND

Ovarian cryopreservation by vitrification is a very effective pathway for the preservation of female fertility during radiotherapy and chemotherapy. However, damage of follicles was triggered by cryo-injure during the process of ovarian vitrification and ischemia/reperfusion during the process of ovarian transplantation. Appropriate FSH play important roles in anti-apoptosis and neoangiogenesis during ovarian follicle development.

OBJECTIVE

Therefore, the purpose of this study was to investigate the effect of FSH on the revascularization and follicular survival of vitrified-warmed ovarian grafts.

MATERIALS AND TMETHODS

Four-week-old C57BL/6J mice with diestrus were used and the ovaries were randomized into the following three groups: fresh control group (FCG), vitrified/warmed group (VCG) and vitrified/warmed group treated with 0.3 IU/mL FSH (FSH-VG) during ovarian vitrification. After warming, the ovaries of the three groups were allotransplanted into the renal capsule of receptor mice. Assessment of follicular quantity was performed by histological analysis. The angiogenesis factors, CD31 and MMP-2, and cell survival factors, PCNA, EdU and survivin were examined by immunohistochemistry and western blot analysis. Angiogenesis was detected by vascular perfusion with the fluorescent dye 2MD-FITC-Dextran.

RESULTS

The expression of CD31and MMP-2 were not significantly different in either VCG or FSH-VG compared with FCG, but when the ovaries were transplanted 48 hours later, the expression levels of CD31 and MMP-2 were lower for VCG than FCG (P < 0.05) and FSH-VG was not significantly different from FCG. Before transplantation, the expression levels of PCNA and survivin were lower for VCG and FSH-VG than FCG (p < 0.05), but FSH-VG was higher than VCG (p < 0.05). After 48 h of ovarian transplantation, the expression of survivin was lower for VCG than FCG (P < 0.05), but FSH-VG was not significantly different from FCG. In addition, these data were further supported by the results from detecting the 2MD-FITC-Dextran and EdU.

CONCLUSION

Taken together, supplementation with 0.3 IU/mL FSH during ovarian cryopreservation by vitrification increased the revascularization and follicular survival for mouse ovarian grafts through the up-regulated expression of angiogenesis and ovarian survival factors.

Responsive Aqueous Foams Stabilized by Silica Nanoparticles Hydrophobized in Situ with a Conventional Surfactant

In the recent past, switchable surfactants and switchable/stimulus-responsive surface-active particles have been of great interest. Both can be transformed between surface-active and surface-inactive states via several triggers, making them recoverable and reusable afterward. However, the synthesis of these materials is complicated. In this paper we report a facile protocol to obtain responsive surface-active nanoparticles and their use in preparing responsive particle-stabilized foams. Hydrophilic silica nanoparticles are initially hydrophobized in situ with a trace amount of a conventional cationic surfactant in water, rendering them surface-active such that they stabilize aqueous foams. The latter can then be destabilized by adding equal moles of an anionic surfactant, and restabilized by adding another trace amount of the cationic surfactant followed by shaking. The stabilization-destabilization of the foams can be cycled many times at room temperature. The trigger is the stronger electrostatic interaction between the oppositely charged surfactants than that between the cationic surfactant and the negatively charged particles. The added anionic surfactant tends to form ion pairs with the cationic surfactant, leading to desorption of the latter from particle surfaces and dehydrophobization of the particles. Upon addition of another trace amount of cationic surfactant, the particles are rehydrophobized in situ and can then stabilize foams again. This principle makes it possible to obtain responsive surface-active particles using commercially available inorganic nanoparticles and conventional surfactants.

A Census of Actively Licensed Physicians in the United States, 2014

Marked changes have occurred in health care delivery in the United States with the implementation of the Affordable Care Act (ACA), including the advancement of integrated health systems, the introduction of patient centered medical homes and the creation of accountable care organizations. With millions of Americans newly insured, never has there been a more pressing need for accurate physician workforce information and planning. Opinions vary about the nature and degree of anticipated physician shortages, and health care workforce determinations are fraught with variables and uncertainties that are challenging to address definitively. Identifying accurate information about the nation's currently licensed physician workforce, however, is an important starting point.

This article reviews data received in 2014 by the Federation of State Medical Boards from the nation's state medical and osteopathic boards about the current supply of actively licensed physicians in the United States and the District of Columbia. Our census data demonstrates the total population of licensed physicians (916,264) has increased by 4% since 2012, and the nation, on average, added 12,168 more licensed physicians annually than it lost. The average physician is now older (by a year), predominantly male (but increasingly female at entry level) and increasingly a graduate of a medical school in the Caribbean. Meanwhile, the percentage of physicians with a single state medical license has remained constant at 79%.