Digital Light Processing 3D-Printed Silica Aerogel and as a Versatile Host Framework for High-Performance Functional Nanocomposites.

Vat-photopolymerization-based 3D printing enables on-demand construction of customized objects with scalable production capacity and high precision. Herein, the sol-gel process for aerogels with digital light processing 3D printing to produce advanced functional materials possessing hierarchical pore structures and complex shapes is combined. It has revealed the temporal evolution of the photorheological behavior of acrylate-modified silica sols in an acid-base catalytic procedure, and confirmed that silica aerogels can be fabricated with very low acrylate content. The resulting aerogels are thermostable with intrinsic silica contents, skeletal densities, and physical characteristics similar to those of commercial silica aerogels yet distinct mechanical behaviors. More importantly, the printed silica aerogels can be used as a versatile nanoengineering platform to produce high-performance and multifunctional interpenetrating phase nanocomposites with complex shapes through programmable post-printing processes. Epoxy-based nanocomposites possessing excellent mechanical performance, ionogel-based conductive nanocomposites with decoupled electrical and mechanical properties, and anti-swelling hydrogel-based nanocomposites are demonstrated. The results of this study offer new guidelines for the design and fabrication of novel materials by additive manufacturing.

Gender, union formation, and assortative mating among older women.

This paper presents a search-theoretic model of union formation among women, aged 55 and older. Specifically, it provides new estimates of gender differentials in cohabitation and marriage at older ages, and documents recent patterns of assortative mating using data from the 2008-2017 American Community Survey. Our analyses reveal that cohabitation represents a much smaller share of all older unmarried women, all partnered women, and all women in comparison to patterns observed among their male counterparts. The results also reveal highly uneven patterns of union formation by age, race and marital history, which reflect demographically uneven constraints and preferences. Our analyses also document, for the first time, patterns of assortative mating at older ages. Shortages of similarly-aged men, especially among older African American women, seemingly heighten the likelihood of demographically mismatched unions. Older women are less likely to form unions with same-race or economically attractive partners, defined as men having a college-degree. This study shows that older single women, in general, are at a comparative disadvantage in the marriage market, both in forming co-residential unions and in finding partners who match their own social, demographic, and economic profiles. This paper highlights considerable heterogeneity in the experiences of America's older women. It calls for new theoretical approaches that acknowledge the unequal resources and bargaining power among older women in the marriage market.

Racial Pairings and Fertility: Do Interracial Couples Have Fewer Children?

OBJECTIVE: Our overall goal is largely descriptive-to compare recent fertility patterns between racially endogamous and exogamous couples in the United States. Evidence of lower fertility among exogamous or interracial couples arguably provides indirect evidence of social distance and cultural and economic integration. BACKGROUND: The growth of interracial marriage and cohabitation has fueled the rise in biracial or mixed-race children. Fertility rates are uneven among racial and ethnic groups, seemingly rooted in stigma and cultural differences (e.g., fertility norms). Whether fertility is different among interracial couples is unclear: Fertility rates that largely conform to the population of racially endogamous White couples provide evidence of social integration whereas differential fertility may reveal gender dynamics in fertility decision-making, including power relationships that depend on the race of male and female partners. METHOD: We pool data from the 2008 to 2017 American Community Survey to compare past-year fertility patterns among endogamously and interracially married and cohabiting couples. RESULTS: Fertility is generally lower among racially exogamous than endogamous unions, especially among Asian American-White couples. Fertility among American Indian-White couples is much closer to patterns of White couples than of American Indian couples. Fertility among other interracial couples nevertheless varies by the race of male partners. That is, fertility of the Black male/White female and the Hispanic male/White female couples is similar to patterns found among endogamous Black and Hispanic couples, respectively. The White male/Black female and the White male/Hispanic female couples follow the fertility patterns of White couples. CONCLUSION: In general, the fertility levels of interracial couples are intermediate between those of endogamous White couples and their endogamous Black, Hispanic, or American Indian counterparts, but vary significantly by the race-gender mix of partners.

Bioinspired "Skin" with Cooperative Thermo-Optical Effect for Daytime Radiative Cooling.

Energy-saving cooling materials with strong operability are desirable for sustainable thermal management. Inspired by the cooperative thermo-optical effect in the fur of a polar bear, we develop a flexible, superhydrophobic, and reusable cooling "skin" by laminating a poly(dimethylsiloxane) film with a highly scattering polyethylene aerogel. Owing to its high porosity (97.9%) and tailored pore size of 3.8 ± 1.4 µm, it can achieve superior solar reflectance (R̅sun ∼ 0.96) and high transparency to irradiated thermal energy (τ̅PE,MIR ∼ 0.8) at a thickness of 2.7 mm. Combined with the low thermal conductivity (0.032 W m-1 K-1) of the aerogel, the cooling skin exerts midday sub-ambient temperature drops of 5-6 °C in a metropolitan environment, with an estimated limit of 14 °C under ideal service conditions. Our generalized bilayer approach can be easily applied to different types of emitters, bridging the gap between night-time and daytime radiative cooling and paving the way for more cost-effective and scalable cooling materials.

Generation, education, and intermarriage of Asian Americans.

The influx of immigrants from Asia to the United States (U.S.) has expanded the pool of coethnic marriageable partners, strengthened racial identity, and contributed to the decline in interracial marriage with whites among Asian Americans. Yet, retreat from interracial marriage with whites may well vary by immigrant generation, an important factor in marital assimilation. Using data from the March Current Population Survey (1994 to 2015), we examine generational differences in intergenerational marriage and interracial marriage with whites among Asian Americans. The results reveal that over time third-plus-generation Asians show no significant change in interracial marriage with whites but declines in intergenerational marriage with first-or second-generation Asians. Second-generation Asians, on the other hand, have become more likely to marry first-generation Asians and less likely to marry whites. In addition, education provides different opportunities for intermarriage, with highly-educated Asian Americans more likely than their less-educated counterparts to marry whites and less likely to marry other Asians. Notably, highly-educated second-generation Asians tend to marry third-plus-generation Asians and whites while their less-educated counterparts marry first-generation Asians. These findings highlight the importance of generation and education in integration of Asian Americans.

Cast-and-Use Super Black Coating Based on Polymer-Derived Hierarchical Porous Carbon Spheres.

Super black materials with extremely low reflectance and high absorption of incident light are crucial in various applications with strict optical requirements. However, the existing super black materials suffer from technical complexity in practical use whereas the underlying physics of their ultralow reflectance is still unclear. Herein, hierarchical porous carbon spheres are prepared using poly(vinylidene chloride- co-vinyl chloride) as a precursor. Dehydrochlorination treatment has proved to be very crucial for the morphology robustness of the porous polymer spheres during carbonization process. Coatings cast from the dispersion of these carbon spheres exhibit a hemispherical reflectance of <0.2% in the visible region and <0.3% in the range of 300-2000 nm, and the lowest reflectance of 0.14% can be reached. This super black coating has great advantages in its easy availability of starting materials, low equipment requirement, and high adaptability onto various substrates. Besides, a theoretical investigation suggests that a small scatterer size and low volume-filling ratio are the two most essential factors in realizing ultralow reflectance, which also offers an instructive guidance for the rational design of super black materials.

Marriage Markets and Intermarriage: Exchange in First Marriages and Remarriages.

Drawing on data from the American Community Survey, we compare patterns of assortative mating in first marriages, remarriages, and mixed-order marriages. We identify a number of ascribed and achieved characteristics that are viewed as resources available for exchange, both as complements and substitutes. We apply conditional logit models to show how patterns of assortative mating among never-married and previously married persons are subject to local marriage market opportunities and constraints. The results reveal that previously married individuals "cast a wider net": spousal pairings are more heterogamous among remarriages than among first marriages. Marital heterogamy, however, is reflected in systematic evidence of trade-offs showing that marriage order (i.e., status of being never-married) is a valued trait for exchange. Never-married persons are better positioned than previously married persons to marry more attractive marital partners, variously measured (e.g., highly educated partners). Previously married persons-especially women-are disadvantaged in the marriage market, facing demographic shortages of potential partners to marry. Marriage market constraints take demographic expression in low remarriage rates and in heterogamous patterns of mate selection in which previously married partners often substitute other valued characteristics in marriage with never-married persons.

Aerogels Derived from Polymer Nanofibers and Their Applications.

Aerogels are gels in which the solvent is supplanted by air while the pores and networks are largely maintained. Owing to their low bulk density, high porosity, and large specific surface area (SSA), aerogels are promising for many applications. Various inorganic aerogels, e.g., silica aerogels, are intensively studied. However, the mechanical brittleness of common inorganic aerogels has seriously restricted their applications. In the past decade, nanofibers have been developed as building blocks for the construction of aerogels to improve their mechanical property. Unlike traditional frameworks constructed by interconnected particles, nanofibers can form chemically cross-linked and/or physically entangled 3D skeletons, thus showing flexibility instead of brittleness. Therefore, excellent elasticity and toughness, ultralow density, high SSA, and tunable chemical composition can be expected for the polymer nanofiber-derived aerogels (PNAs). In this review, recent research progress in the fabrication, properties, and applications of PNAs is summarized. Various nanofibers, including nanocelluloses, nanochitins, and electrospun nanofibers are included, as well as carbon nanofibers from the corresponding organic precursors. Typical applications in supercapacitors, electrocatalysts for oxygen reduction reaction, flexible electrodes, oil absorbents, adsorbents, tissue engineering, stimuli-responsive materials, and catalyst carriers, are presented. Finally, the challenges and future development of PNAs are discussed.

Transitions From Sexual Relationships Into Cohabitation and Beyond.

Much research on cohabitation has focused on transitions from cohabitation to marriage or dissolution, but less is known about how rapidly women progress into cohabitation, what factors are associated with the tempo to shared living, and whether the timing into cohabitation is associated with subsequent marital transitions. We use data from the 2006-2013 National Survey of Family Growth to answer these questions among women whose most recent sexual relationship began within 10 years of the interview. Life table results indicate that transitions into cohabitation are most common early in sexual relationships; nearly one-quarter of women had begun cohabiting within six months of becoming sexually involved. Multivariate analyses reveal important social class disparities in the timing to cohabitation. Not only are women from more-advantaged backgrounds significantly less likely to cohabit, but those who do cohabit enter shared living at significantly slower tempos than women whose mothers lacked a college degree. In addition, among sexual relationships that transitioned into cohabiting unions, college-educated women were significantly more likely to transition into marriage than less-educated women. Finally, although the tempo effect is only weakly significant, women who moved in within the first year of their sexual relationship demonstrated lower odds of marrying than did women who deferred cohabiting for over a year. Relationship processes are diverging by social class, contributing to inequality between more- and less-advantaged young adults.

Superhydrophobic/Superhydrophilic Janus Fabrics Reducing Blood Loss.

Hemostatic fabrics are most commonly used in baseline emergency treatment; however, the unnecessary blood loss due to the excessive blood absorption by traditional superhydrophilic fabrics is overlooked. Herein, for the first time, superhydrophobic/superhydrophilic Janus fabrics (superhydrophobic on one side and superhydrophilic on the other) are proposed: the superhydrophilic part absorbs water in the blood to expedite the clotting while the superhydrophobic part prevents blood from further permeating. Compared with the common counterparts, effective bleeding control with reducing blood loss more than 50% can be achieved while the breathability largely remain by using Janus fabrics. The proposed prototypes can even prolong the survival time in the rat model with serious bleeding. This strategy for reducing blood loss via simply tuning wettability is promising for the practical applications.

Divergent Pathways to Assimilation? Local Marriage Markets and Intermarriage among U.S. Hispanics.

The growing diversity of the U.S. population raises questions about integration among America's fastest growing minority population-Hispanics. The canonical view is that intermarriage with the native-born white population represents a singular pathway to assimilation, one that varies over geographic space in response to uneven local marital opportunities. Using data on past-year marriage from the 2009-2014 American Community Survey, we demonstrate high rates of intermarriage among Hispanics. Our analyses identify whether Hispanics marry co-ethnics, non-co-ethnic Hispanics, non-Hispanic whites, non-Hispanic blacks, or other minorities. We highlight variation by race, nativity, and socioeconomic status, but also reveal that Hispanics living in new immigrant destinations are more likely to intermarry than those living in traditional Hispanic gateways. Indeed, the higher out-marriage in new destinations disappears when the demographic context of reception is taken into account. Our analysis underscores that patterns of marital assimilation among Hispanics are neither monolithic nor expressed uniformly across geographic space.

Hukou Locality and Intermarriages in Two Chinese Cities: Shanghai and Shenzhen.

China's household registration system (hukou) has created an institutional boundary for the social integration of migrants, but few studies have explored if hukou barriers vary by city. We investigate the value of hukou locality in Shanghai and Shenzhen by comparing their patterns of intermarriage between locals and migrants. We hypothesize that levels of intermarriage reflect the rigidity of the hukou barrier- the likelihood of intermarriage is lower and tradeoffs for local hukou are higher if one city has more stringent hukou policies than the other. Using data from the 2005 mini-census, we find support for our hypothesis. Shanghai, in which internal migrants in China find it most difficult to secure local hukou, exhibits lower levels of intermarriage and lower levels of hukou locality-education exchange between locals and migrants compared to Shenzhen. The findings suggest that the decentralization of China's hukou system and subsequent varying hukou policies have made hukou locality an increasingly salient factor in shaping migrants' integration and social inequality.

Boundary Blurring? Racial Identification among the Children of Interracial Couples.

For America's children, racial and ethnic identity is complicated by the fact that interracial couples define their children's racial and ethnic identity rather than the children themselves. The commonplace idea of racial self-identification in government surveys is a misnomer for America's children. In this paper, we use data, pooled annually, from the 2008 to 2014 American Community Survey to document (1) recent fertility patterns among interracially married couples, and (2) the racial or ethnic identification of the children from interracial marriages. A sizeable minority share of America's children from mixed-race marriages are identified by their parents as monoracial, which suggests that mixed-race children are seriously underreported. Moreover, the assignment of race is highly uneven across interracial marriages comprised of husbands and wives with different racial backgrounds. Our result suggest that children's racial identity reflects a kind of racial "tug-of-war" between parents who bring their own racial and cultural identities to marriages. The status or power of parents is often unequal, and this is played out in how children are identified as their biological offspring. For example, the parents from minority populations often have fewer claims on the race of their children. The racial and ethnic identities of children of interracial marriages, at a minimum, are highly subjective and complex.

Unemployment and the Transition From Separation to Divorce.

Informal marital separation often quickly leads to divorce, but can become long-lasting, especially among disadvantaged populations. In this study, we focus on the timing of divorce after separating and examine how unemployment before or during separation affects this pivotal moment in the divorce process. Using data from the National Longitudinal Survey of Youth, 1979 Cohort (N = 2,219), we track unemployment before and during separation and show that men's unemployment during separation, rather than women's, reduces the likelihood of divorce, independent of preseparation unemployment and other characteristics. For men, unemployment during a marital separation prolongs the divorce process, creating an extended period of uncertainty in marital relationships on the brink of dissolution. We discuss the gendered relationship observed between employment status during an informal separation and an estranged couple's decision to complete the divorce process.

Assortative Mating by Education and Hukou in Shanghai.

Previous research on Hukou-based stratification mostly focuses on Hukou-derived labor market outcomes, with growing attention paid to the role of Hukou locality (local vs. nonlocal) as an increasingly important agent of social stratification in urban China. Few studies have, however, examined how Hukou shapes the patterns of who marries whom in geographically-defined marriage markets, despite the far-reaching implications of assortative mating for migrant integration into the host society, economic inequality among families, and intergenerational transmissions of social traits. In this paper, using a most recent, representative sample of the post-'80s generation living in Shanghai, we evaluate how Hukou locality intersects with educational attainment to shape assortative marriage patterns. We find that highly-educated Hukou residents and non-Hukou migrants are both more likely than their less-educated counterparts to marry a Hukou resident, suggesting that Shanghai Hukou is a valuable attribute in Shanghai marriage market. In addition, Hukou intermarriage seldom occurs when Hukou residents marry a non-Hukou migrant with less education than themselves. The results indicate that Hukou locality is an important stratifier in contemporary China that shapes marriage market conditions and individual mating choices.

Does higher education expansion promote educational homogamy? Evidence from married couples of the post-80s generation in Shanghai, China.

The expansion of higher education witnessed in many societies influences the pattern of educational assortative mating. Structural transition theory predicts growing educational homogamy due to increasing preference for highly-educated partners who become more widely available. In contrast, social closure theory suggests depressed educational homogamy because the inflation of the education elite circle fosters the openness of marriage market, reducing the preference for a highly-educated mate and increasing the penetrability across social-status boundaries. Capitalizing the survey data that are representative of the post-80s one-child generation collected in Shanghai, China, we test the hypotheses derived from the two theories. Empirical results suggest that, with increasing availability of highly educated individuals, the extent of educational homogamy by birth cohort reveals a U-shaped pattern. This U-shaped pattern demonstrates increasing levels of educational homogamy and lends support to structural transition theory.

Gendered transitions to adulthood by college field of study in the United States.

BACKGROUND: Field of study may influence the timing of transitions to the labor market, marriage, and parenthood among college graduates. Research to date has yet to study how field of study is associated with the interweaving of these transitions in the USA. OBJECTIVE: The current study examines gendered influences of college field of study on transitions to a series of adult roles, including full-time work, marriage, and parenthood. METHODS: We use Cox proportional hazards models and multinomial logistic regression to examine gendered associations between field of study and the three transitions among college graduates of the NLSY97 (National Longitudinal Survey of Youth) cohort. RESULTS: Men majoring in STEM achieve early transitions to full-time work, marriage, and parenthood; women majoring in STEM show no significant advantage in finding full-time work and delayed marriage and childbearing; women in business have earlier transitions to full-time work and marriage than women in other fields, demonstrating an advantage similar to that of men in STEM. CONCLUSIONS: The contrast between men and women in STEM shows that transition to adulthood remains gendered; the contrast between women in STEM and women in business illustrates that a prestigious career may not necessarily delay family formation.

Robust superhydrophobic bridged silsesquioxane aerogels with tunable performances and their applications.

Aerogels are a family of highly porous materials whose applications are commonly restricted by poor mechanical properties. Herein, thiol-ene chemistry is employed to synthesize a series of novel bridged silsesquioxane (BSQ) precursors with various alkoxy groups. On the basis of the different hydrolyzing rates of the methoxy and ethoxy groups, robust superhydrophobic BSQ aerogels with tailorable morphology and mechanical performances have been prepared. The flexible thioether bridge contributes to the robustness of the as-formed aerogels, and the property can be tuned on the basis of the distinct combinations of alkoxy groups with the density of the aerogels almost unchanged. To the best of our knowledge, the lowest density among the ambient pressure dried aerogels is obtained. Further, potential application of the aerogels for oil/water separation and acoustic materials has also been presented.

Rh(III)-catalyzed regioselective hydroarylation of alkynes via directed C-H functionalization of pyridines.

Rh(III)-catalyzed C-3 selective alkenylation of pyridine derivatives via hydroarylation of alkynes has been developed. The reaction shows high regioselectivity, high yield and good functional group tolerance, providing a convenient strategy for the synthesis of trisubstituted (pyridin-3-yl)alkenes.

Obesity and mortality risk: new findings from body mass index trajectories.

Little research has addressed the heterogeneity and mortality risk in body mass index (BMI) trajectories among older populations. Applying latent class trajectory models to 9,538 adults aged 51 to 77 years from the US Health and Retirement Study (1992-2008), we defined 6 latent BMI trajectories: normal weight downward, normal weight upward, overweight stable, overweight obesity, class I obese upward, and class II/III obese upward. Using survival analysis, we found that people in the overweight stable trajectory had the highest survival rate, followed by those in the overweight obesity, normal weight upward, class I obese upward, normal weight downward, and class II/III obese upward trajectories. The results were robust after controlling for baseline demographic and socioeconomic characteristics, smoking status, limitations in activities of daily living, a wide range of chronic illnesses, and self-rated health. Further analysis suggested that BMI trajectories were more predictive of mortality risk than was static BMI status. Using attributable risk analysis, we found that approximately 7.2% of deaths after 51 years of age among the 1931-1941 birth cohort were due to class I and class II/III obese upward trajectories. This suggests that trajectories of increasing obesity past 51 years of age pose a substantive threat to future gains in life expectancy.