A sinterless, low-temperature route to 3D print nanoscale optical-grade glass

Three-dimensional (3D) printing of silica glass is dominated by techniques that rely on traditional particle sintering. At the nanoscale, this limits their adoption within microsystem technology, which prevents technological breakthroughs. We introduce the sinterless, two-photon polymerization 3D printing of free-form fused silica nanostructures from a polyhedral oligomeric silsesquioxane (POSS) resin. Contrary to particle-loaded sacrificial binders, our POSS resin itself constitutes a continuous silicon-oxygen molecular network that forms transparent fused silica at only 650°C. This temperature is 500°C lower than the sintering temperatures for fusing discrete silica particles to a continuum, which brings silica 3D printing below the melting points of essential microsystem materials. Simultaneously, we achieve a fourfold resolution enhancement, which enables visible light nanophotonics. By demonstrating excellent optical quality, mechanical resilience, ease of processing, and coverable size scale, our material sets a benchmark for micro- and nano-3D printing of inorganic solids.

Tensegrity Metamaterials: Toward Failure-Resistant Engineering Systems through Delocalized Deformation

Failure of materials and structures is inherently linked to localized mechanisms, from shear banding in metals, to crack propagation in ceramics and collapse of space-trusses after buckling of individual struts. In lightweight structures, localized deformation causes catastrophic failure, limiting their application to small strain regimes. To ensure robustness under real-world nonlinear loading scenarios, overdesigned linear-elastic constructions are adopted. Here, the concept of delocalized deformation as a pathway to failure-resistant structures and materials is introduced. Space-tileable tensegrity metamaterials achieving delocalized deformation via the discontinuity of their compression members are presented. Unprecedented failure resistance is shown, with up to 25-fold enhancement in deformability and orders of magnitude increased energy absorption capability without failure over same-strength state-of-the-art lattice architectures. This study provides important groundwork for design of superior engineering systems, from reusable impact protection systems to adaptive load-bearing structures.

A-06 Current Norms May Overestimate Rates of Neurocognitive Impairment among American Indian and Alaskan Native Adults

Objective

Currently available normative data subsume American Indian and Alaskan Native (AI/AN) populations within the non-Latinx white (NLW) ethnoracial group. The classification accuracy of such norms among AI/AN remains unknown. This cross-sectional study aims to identify whether disparities exist in the rates of neurocognitive impairment (NCI) between AI/AN and NLW adults. < br><br > 

Method

Two hundred community-dwelling adults (50% NLW; 50% Male; M Age = 42 ± 14 years; M Education = 13 ± 3 years) completed comprehensive neurocognitive, quality of education (Wide Range Achievement Test- 4 [WRAT-4]), neuromedical, urine toxicology, and psychiatric/substance use evaluations. Average T-scores were calculated using widely used demographically corrected (age, gender, education) NLW norms to identify NCI (> 1 SD; e.g., Heaton et al., 2004; Heaton & Marcotte, 2000). A comorbid condition propensity score (CCPS) identified the probability to which comorbid conditions (e.g., Heaton et al., 2010) informed ethnoracial identity. <br><br > 

Results

After adjusting for WRAT-4 and CCPS, the results of a logistic regression analysis demonstrated a significant ethnoracial disparity in risk for NCI (X2(3) = 13.88, p<.01, R2 = .07), such that the AI/AN group was at 2.52 times higher odds (32.3% vs. 16.0, CI: 1.15–5.46, p = .01, Cohen’s d = .51) for NCI in comparison to the NLW group. <br><br > 

Conclusions

Published norms for NLW adults may overestimate impairment in AI/AN adults. Thus, population-specific normative data are needed to clarify the classification accuracy of neurocognitive impairment and possible disparities in neurocognitive disorders (e.g., HIV-associated neurocognitive disorders) among AI/AN adults. Future work should replicate these findings among other diverse populations (e.g., Caribbean, Middle Eastern) lacking population-specific normative data.876199.

Evolution of hot zone care: MARA

Modern conflict and terrorist events have moved from linear two-dimensional battlespaces into complex, continuously evolving three-dimensional environments. Contested spaces make traditional definitions of zones of response confusing and lead to delays in care. The presence of actual or perceived ongoing threats creates an environment in which the initiation of tactical field care (TFC) may be inappropriate, despite the absence of an immediate risk to life. This risks a 'time and space gap' between care under fire and TFC. Major haemorrhage, airway, respiration, analgesia is proposed as a rethought approach to care in such environments.

Plate-nanolattices at the theoretical limit of stiffness and strength

Though beam-based lattices have dominated mechanical metamaterials for the past two decades, low structural efficiency limits their performance to fractions of the Hashin-Shtrikman and Suquet upper bounds, i.e. the theoretical stiffness and strength limits of any isotropic cellular topology, respectively. While plate-based designs are predicted to reach the upper bounds, experimental verification has remained elusive due to significant manufacturing challenges. Here, we present a new class of nanolattices, constructed from closed-cell plate-architectures. Carbon plate-nanolattices are fabricated via two-photon lithography and pyrolysis and shown to reach the Hashin-Shtrikman and Suquet upper bounds, via in situ mechanical compression, nano-computed tomography and micro-Raman spectroscopy. Demonstrating specific strengths surpassing those of bulk diamond and average performance improvements up to 639% over the best beam-nanolattices, this study provides detailed experimental evidence of plate architectures as a superior mechanical metamaterial topology.

Plate-lattices are predicted to reach the upper bounds of strength and stiffness compared to traditional beam-lattices, but they are difficult to manufacture. Here, the authors use two-photon polymerization 3D-printing and pyrolysis to make carbon plate-nanolattices which reach those theoretical bounds, making them up to 639% stronger than beam-nanolattices.

Ultrahigh Energy Absorption Multifunctional Spinodal Nanoarchitectures

Nanolattices are promoted as next-generation multifunctional high-performance materials, but their mechanical response is limited to extreme strength yet brittleness, or extreme deformability but low strength and stiffness. Ideal impact protection systems require high-stress plateaus over long deformation ranges to maximize energy absorption. Here, glassy carbon nanospinodals, i.e., nanoarchitectures with spinodal shell topology, combining ultrahigh energy absorption and exceptional strength and stiffness at low weight are presented. Noncatastrophic deformation up to 80% strain, and energy absorption up to one order of magnitude higher than for other nano-, micro-, macro-architectures and solids, and state-of-the-art impact protection structures are shown. At the same time, the strength and stiffness are on par with the most advanced yet brittle nanolattices, demonstrating true multifunctionality. Finite element simulations show that optimized shell thickness-to-curvature-radius ratios suppress catastrophic failure by impeding propagation of dangerously oriented cracks. In contrast to most micro- and nano-architected materials, spinodal architectures may be easily manufacturable on an industrial scale, and may become the next generation of superior cellular materials for structural applications.

Does Decision-Making Ability Predict HIV-Associated Neurocognitive Disorder?

Background

Executive dysfunction (EF) in people living with HIV (PLWH) is well-established. However, decision-making, a key aspect of EF, is often overlooked in neurocognitive (NC) evaluations of PLWH. Poor decision-making can detrimentally impact PLWH by increasing risk of poor health outcomes. This study aimed to determine if including a decision-making task in NC evaluations might improve diagnostic formulations.

Participants and Method

This cross-sectional study included 90 PLWH (63 Latinx; 27 non-Latinx white) who were evaluated for HIV-Associated Neurocognitive Disorder (HAND) using established criteria, with the Wisconsin Card Sorting Test (WCST) and Trail Making Test Part B (TMTB) comprising the “traditional” EF domain. The Iowa Gambling Task (IGT) assessed decision-making. Demographically corrected T-scores were calculated for each test. The “traditional” EF tests were averaged into an EF domain T-score. The WCST, TMTB, and IGT were also averaged into a “new” EF+IGT domain T-score.

Results

The new EF+IGT domain T-score significantly predicted HAND diagnosis (R^2 = .14, p < .001). However, using hierarchical regression, the “traditional” EF domain (WCST and TMTB) also significantly predicted HAND (R^2 = .18, p < .001) and adding the IGT Total T-score did not contribute unique variance to the model (R^2 = .18, p < .001; R^2Δ < .001, pΔ = .92).

Conclusions

A new combined EF domain T-score that included decision-making was a significant predictor of HAND diagnosis. However, adding IGT Total Score did not enhance HAND diagnosis compared to “traditional” EF measurement, indicating that the “traditional” EF domain adequately informs HAND diagnosis. A limitation of this study was the small sample size. Given the important health implications of decision-making in PLWH, future research, with a larger sample size is warranted to better conceptualize how decision-making can be incorporated into diagnostic formulations for PLWH.

Advancing Science Through Diversity and Inclusion in the Editorial Process: A Case Study

Objective

In the U.S., women and culturally/linguistically diverse persons are underrepresented in research and editorial boards. This case study details how one journal, The Clinical Neuropsychologist (TCN), created and implemented a strategic plan to advance diversity and inclusion in its editorial board and process.

Case Description

In 2015, Dr. Yana Suchy became TCN’s first female Editor-in-Chief; and in 2016, she created the Culture and Gender in Neuropsychology Department (CGND). The CGND’s Editors are Drs. Rivera Mindt and Hilsabeck, and their mission is to diversify science and empirically-based practice within neuropsychology by (1) increasing representation of editors/reviewers from diverse backgrounds; (2) soliciting articles related to gender/culture; (3) providing resources addressing diversity issues; and (4) demonstrating editorial leadership via editorial content.

Diagnostic Impressions and Outcomes

In 2015, only 23% of TCN editors were women and only 2% were from diverse backgrounds. By 2018, representation of these groups increased to 50% and 13%, respectively. Also, in 2018 TCN published its first special issue on gender, numerous articles on culturally diverse populations, and the first guideline for evaluation of transgender persons. An upcoming special issue will focus on normative data for Spanish-speakers. Resources available include a Publication Guidelines Checklist, formal presentations, and informal communications (social media) to educate and engage stakeholders and consultors. These accomplishments were recently highlighted in the inaugural CGND editorial (2018).

Discussion

Over the last three years, TCN has taken steps to increase representation of gender- and culturally/linguistically-relevant content, editorial leadership, and professional development; thereby demonstrating that this is a tangible goal. This case study serves as a call to action for other journals to follow suit and further diversify science.

References

Rivera Mindt, M., Hilsabeck, R. C., Olsen, J. P., Savin, M. J., Crook, C. L., & Suchy, Y. Advancing science through diversity and inclusion in the editorial process: A case study. Science Editor, 41(3), 93-96. Rivera Mindt, M. & Hilsabeck, R. C. (2018) TCN culture and gender in Neuropsychology Department: inaugural editorial. The Clinical Neuropsychologist, 32(8), 1353-1355, DOI: 10.1080/13854046.2018.1525110. Hilsabeck, R. C. (2018) Editorial: Raising awareness about gender bias and disparity in clinical neuropsychology and a call to action. ClinNeuropsychol, 32,183–185. https://doi.org/10.1080/13854046.2018.1525110. Fujii, D. E. M. (2018) Developing a cultural context for conducting a neuropsychological evaluation with a culturally diverse client: The ECLECTIC framework. The Clinical Neuropsychologist, 32(8), 1356-1392, DOI: 10.1080/13854046.2018.1435826. Trittschuh, E. H., Parmenter, B. A., Clausell, E. R., Mariano, M. J. & Reger, M. A. (2018) Conducting neuropsychological assessment with transgender individuals. The Clinical Neuropsychologist, 32(8), 1393-1410, DOI: 10.1080/13854046.2018.1440632. Nielsen, T. R., Segers, K., Vanderaspoilden, V., Bekkhus-Wetterberg, P., Minthon, L., Pissiota, A., Bjørkløf, G. H., Beinhoff, U., Tsolaki, M., Gkioka, M., & Waldemar G. (2018) Performance of middle-aged and elderly European minority and majority populations on a Cross-Cultural Neuropsychological Test Battery (CNTB). The Clinical Neuropsychologist, 32(8), 1411-1430, DOI: 10.1080/13854046.2018.1430256. Suhr J. A., Ready R., Rosen W. G., Hilsabeck, R. C., & Ploetz, D. M. The changing face of neuropsychology: gender disparities and strategies for addressing them. CE workshop presented at the 37th annual conference of the National Academy of Neuropsychology, Boston, MA, 2017. Hilsabeck, R. C., Sweet J., Forrest B., Sachs B., & Kubu, C. Gender and the profession of neuropsychology: where we’ve been and where we need to go. CE workshop presented at the 15th Annual Conference of the American Academy of Clinical Neuropsychology, Boston, MA, 2017. Rivera Mindt, M. 2018. The Clinical Neuropsychologist: increasing diversity & inclusion. Council of Science Editors, TechnicaEditorial Services Webinar: The Peer Review Ecosystem: Where Does Diversity & Inclusion Fit In? [accessed 2018 Oct 9]. https://www.youtube.com/watch?v=7cixedlVR0o&feature=youtu.be.

Subsite mapping of enzymes. Double inhibition studies

Our earlier subsite mapping studies led us to believe that ground state distortion occurred when a glucopyranoside ring filled the site which held the substrate monomer unit transferred to water during hydrolysis. We tested this hypothesis by performing double inhibitor studies on two amylases (EC 3.2.1.1) of bacterial origin. A general theory for multiple inhibition of this type is developed and applied to these two enzymes. Our data are consistent with the hypothesis that ground state strain occurs when substrates are bound to carbohydrates. An explanation is offered to account for the fact that monomers give strictly competitive inhibition patterns. The subsite model predicts that noncompetitive or mixed inhibition patterns can occur.