Neurocognitive change over the course of a multiday external lumbar drain trial in patients with suspected normal pressure hydrocephalus.

Objective: To characterize neurocognitive response to cerebrospinal fluid (CSF) diversion during a multiday external lumbar drainage (ELD) trial in patients with suspected normal pressure hydrocephalus (NPH). Methods: Inpatients (N = 70) undergoing an ELD trial as part of NPH evaluation participated. Cognition and balance were assessed using standardized measures before and after a three-day ELD trial. Cognitive change pre- to post-ELD trial was assessed in relation to change in balance, baseline neuroimaging findings, NPH symptoms, demographics, and other disease-relevant clinical parameters. Results: Multiday ELD resulted in significant cognitive improvement (particularly on measures of memory and language). This improvement was independent of demographics, test-retest interval, number of medical and psychiatric comorbidities, NPH symptom duration, estimated premorbid intelligence, baseline level of cognitive impairment, cerebrovascular disease burden, degree of ventriculomegaly, or other NPH-related morphological brain alterations. Balance scores evidenced a greater magnitude of improvement than cognitive scores and were weakly, but positively correlated with cognitive change scores. Conclusions: Findings suggest that cognitive improvement associated with a multiday ELD trial can be sufficiently captured with bedside neurocognitive testing. These findings support the utility of neuropsychological consultation, along with balance assessment, in informing clinical decision-making regarding responsiveness to temporary CSF diversion for patients undergoing elective NPH evaluation. Implications for the understanding of neuroanatomical and cognitive underpinnings of NPH are discussed.

Perceived cognitive impairment is related to internalizing psychopathology but unrelated to objective cognitive performance among nongeriatric adults presenting for outpatient neuropsychological evaluation.

Objective: This study investigated the relationship between perceived cognitive impairment, objective cognitive performance, and intrapersonal variables thought to influence ratings of perceived cognitive impairment. Method: Study sample comprised 194 nongeriatric adults who were seen in a general outpatient neuropsychology clinic for a variety of referral questions. The cognition subscale score from the WHO Disability Assessment Schedule served as the measure of perceived cognitive impairment. Objective cognitive performance was indexed via a composite score derived from a comprehensive neuropsychological battery. Internalizing psychopathology was indexed via a composite score derived from anxiety and depression measures. Medical and neuropsychiatric comorbidities were indexed by the number of different ICD diagnostic categories documented in medical records. Demographics included age, sex, race, and years of education. Results: Objective cognitive performance was unrelated to subjective concerns, explaining <1% of the variance in perceived cognitive impairment ratings. Conversely, internalizing psychopathology was significantly predictive, explaining nearly one-third of the variance in perceived cognitive impairment ratings, even after accounting for test performance, demographics, and number of comorbidities. Internalizing psychopathology was also highly associated with a greater discrepancy between scores on perceived and objective cognitive measures among participants with greater cognitive concerns. Clinically significant somatic symptoms uniquely contributed to the explained variance in perceived cognitive impairment (by ∼13%) when analyzed in a model with internalizing symptoms. Conclusions: These findings suggest that perceived cognitive impairment may be more indicative of the extent of internalizing psychopathology and somatic concerns than cognitive ability.

Functional silicone oils and elastomers: new routes lead to new properties.

Silicones are mostly utilized for their stability to a range of vigorous environmental conditions, which arises, in part, from the lack of functionality in finished products. The commonly used functional groups in silicones, e.g., SiH, SiCHCH2, are mostly consumed during final product synthesis. Organic functional groups may also be found in silicone products, including organic alcohols, amines, polyethers, etc., that deliver functionality not achieved by traditional organic polymers (e.g., aminosilicones, softening of fabrics; silicone polyethers, superwetting agricultural adjuvants). However, relatively little organic chemistry is practiced in commercial silicones, limiting the types of desirable functionality that can be attained. We report the utilization of a series of simple-to-practice organic reactions that take place efficiently on silicone oils to allow the preparation of a wide variety of functional silicones. The silicone oil starting materials typically act as both solvent and educt to allow many of the newer reactions, such as Click processes, to be used to tune the properties of both silicone oil and elastomer products. The review considers the concept of 'functionality' to include: the reactive groups used to enable synthesis of more complicated structures; and separately, the functional properties of the product silicones. One such property that is considered throughout is degradability at end-of-life, which is related to the sustainability of silicones.

Exploring Lipoic Acid-Mediated Dynamic Bottlebrush Elastomers as a New Platform for the Design of High-Performance Thermally Conductive Materials.

The development of high-performance thermally conductive interface materials is the key to unlocking the serious bottleneck of modern microelectronic technology through enhanced heat dispersion. Existing methods that utilize silicone composites rely either on loading large doses of randomly distributed thermal conductive fillers or on filling prealigned thermal conductive scaffolds with liquid silicone precursors. Both approaches suffer from several limitations in terms of physical traits and processability. We describe an alternative approach in which malleable silicone matrices, based on the dynamic cyclic disulfide nature cross-linker (α-lipoic acid), are readily prepared using ring-opening polymerization. The mechanical properties of the resultant dynamic silicone matrix are readily tunable. Stress-dependent depolymerization of the disulfide network demonstrates the ability to reprocess the silicone elastomer matrix, which allows for the fabrication of highly efficient thermal conductive composites with a 3D interconnecting, thermally conductive network (3D-graphite/MxBy composites) via in situ methods. Applications of the composites as thermal dispersion interface materials are demonstrated by LEDs and CPUs, suggesting great potential in advanced electronics.

Antioxidant Silicone Elastomers without Covalent Cross-Links.

Improved sustainability is associated with elastomers that readily breakdown in the environment at end of life and, as importantly, that can be reprocessed/reused long before end of life arises. We report the preparation of silicone elastomers that possess both thermoplasticity-reprocessability-and antioxidant activity. A combination of ionic and H-bonding links natural phenolic antioxidants, including catechol, pyrogallol, tannic acid, and others, to telechelic aminoalkylsilicones. The mechanical properties of the elastomers, including their processability, are intimately linked to the ratio of [ArOH]/[H2NR] that was found to be optimal when the ratio exceeded 1:1.

Preparation of ultra-thin elastomeric films.

When polydimethylsiloxane elastomers are produced, in the absence of great care, chains remain that are unbound to the cross-linked matrix. Due to the unbound chains swelling the crosslinked matrix, these materials are gels. We have developed a simple process to prepare well-controlled elastomeric thin films which do not rely on unknown commercial formulations.

Starch-Directed Synthesis of Worm-Shaped Silica Microtubes.

Many strategies have been adopted to prepare silica materials with highly controlled structures, typically using sol-gel chemistry. Frequently, the alkoxysilanes used in sol-gel chemistry are based on monoalcohols, e.g., Si(OEt)4. The structural control over silica synthesis achieved by these precursors is highly sensitive to pH and solvency. Alkoxysilanes derived from the sugar alcohol glycerol (diglycerylsilane) react more slowly and with much less sensitivity to pH. We report that, in the presence of cooled aqueous starch solutions, glyceroxysilanes undergo transesterification with the sugars on starch, leading to (hollow) microtubules resembling worms of about 400 nm in diameter. The tubes arise from the pre-assembly of starch bundles, which occurs only well below room temperature. It is straightforward to treat the first-formed starch/silica composite with the enzyme amylase to, in a programmed fashion, increasingly expose porosity, including the worm morphology, while washing away untethered silica and digested starch to leave an open, highly porous materials. Sintering at 600 °C completely removes the starch silane moieties.

Profile of Embedded Validity Indicators in Criminal Defendants with Verified Valid Neuropsychological Test Performance.

OBJECTIVE: Few studies have examined the use of embedded validity indicators (EVIs) in criminal-forensic practice settings, where judgements regarding performance validity can carry severe consequences for the individual and society. This study sought to examine how various EVIs perform in criminal defendant populations, and determine relationships between EVI scores and intrapersonal variables thought to influence performance validity. METHOD: Performance on 16 empirically established EVI cutoffs were examined in a sample of 164 criminal defendants with valid performance who were referred for forensic neuropsychological evaluation. Subsequent analyses examined the relationship between EVI scores and intrapersonal variables in 83 of these defendants. RESULTS: Half of the EVIs (within the Wechsler Adult Intelligence Scale Digit Span Total, Conners' Continuous Performance Test Commissions, Wechsler Memory Scale Logical Memory I and II, Controlled Oral Word Association Test, Trail Making Test Part B, and Stroop Word and Color) performed as intended in this sample. The EVIs that did not perform as intended were significantly influenced by relevant intrapersonal variables, including below-average intellectual functioning and history of moderate-severe traumatic brain injury and neurodevelopmental disorder. CONCLUSIONS: This study identifies multiple EVIs appropriate for use in criminal-forensic settings. However, based on these findings, practitioners may wish to be selective in choosing and interpreting EVIs for forensic evaluations of criminal court defendants.

Ascorbic Acid-Modified Silicones: Crosslinking and Antioxidant Delivery.

Vitamin C is widely used as an antioxidant in biological systems. The very high density of functional groups makes it challenging to selectively tether this molecule to other moieties. We report that, following protection of the enediol as benzyl ethers, the introduction of an acrylate ester at C1 is straightforward. Ascorbic acid-modified silicones were synthesized via aza-Michael reactions of aminoalkylsilicones with ascorbic acrylate. Viscous oils formed when the amine/acrylate ratios were <1. However, at higher amine/acrylate ratios with pendent silicones, a double reaction occurred to give robust elastomers whose modulus is readily tuned simply by controlling the ascorbic acid amine ratio that leads to crosslinks. Reduction with H2/Pd removed the benzyl ethers and led to increased crosslinking, and either liberated the antioxidant small molecule or produced antioxidant elastomers. These pro-antioxidant elastomers show the power of exploiting natural materials as co-constituents of silicone polymers.

A Measurement-Based Protocol Improves Interrater Agreement and Accuracy of Right Ventricular Systolic Pressure Assessment by Echocardiography in Children: A Call for Quality Improvement.

BACKGROUND: Echocardiographic measurements carry the promise of improving interrater (IR) agreement over subjective assessment. The aim of this study was to assess the effect of implementing a measurement-based protocol on IR agreement and accuracy in reporting of right ventricular (RV) systolic pressure in children. The effect of this reporting protocol on IR agreement in reporting RV dilation, hypertrophy, and systolic function was also evaluated. METHODS: Five echocardiography readers reported their assessment of RV systolic pressure, dilation, hypertrophy, and systolic function on 40 deidentified echocardiograms using their individual accustomed methods and then using an agreed-upon protocol based solely on RV measurements. IR agreement was assessed using κ statistics. Accuracy of RV systolic pressure ratings was assessed using the McNemar test in comparison with hemodynamic data obtained by cardiac catheterization. The reliability of the RV measurements was assessed using intraclass correlation coefficient (ICC) and coefficient of variation. RESULTS: IR agreement and accuracy of RV systolic pressure assessment improved after using the measurement-based protocol (agreement from 0.39 [95% CI, 0.27-0.5] to 0.62 [95% CI, 0.48-0.76] and accuracy from 18 of 40 to 29 of 40 [P = .03]). IR agreement of RV dilation improved (from 0.36 [95% CI, 0.25-0.48] to 0.63 [95% CI, 0.48-0.79]), while IR agreement of RV hypertrophy (from 0.29 [95% CI, 0.17-0.42] to 0.35 [95% CI, 0.15-0.55]) and RV systolic function (from 0.57 [95% CI, 0.45-0.69] to 0.53 [95% CI, 0.41-0.66]) did not improve. The reliability of the measurements was good (ICC > 0.8), except for RV free wall thickness (ICC = 0.62, coefficient of variation = 24%) and RV fractional area change (ICC = 0.47, coefficient of variation = 22%), suggesting a possible reason for the lack of improvement in IR agreement of RV hypertrophy and RV systolic function. Heteroscedasticity was observed in the reliability of RV measurements, with the ICC being significantly lower at larger magnitudes for all RV measurements. CONCLUSIONS: Standardization of reporting protocols using RV measurements in place of subjective assessment improved IR agreement and accuracy of RV systolic pressure assessment. Reliable measurements (RV systolic pressure and dilation) resulted in improvement in IR agreement while unreliable measurements (RV hypertrophy and systolic function) did not. Special attention to measurements' reliability and heteroscedasticity of reliability is required when designing clinical protocols to decrease IR disagreement as a source of error.

Chelating Silicone Dendrons: Trying to Impact Organisms by Disrupting Ions at Interfaces.

The viability of pathogens at interfaces can be disrupted by the presence of (cationic) charge and chelating groups. We report on the synthesis of silicone dendrimers and linear polymers based on a motif of hexadentate ligands with the ability to capture and deliver metal ions. Mono-, di- or trialkoxysilanes are converted in G1 to analogous vinylsilicones and then, iteratively using the Piers-Rubinsztajn reaction and hydrosilylation, each vinyl group is transformed into a trivinyl cluster at G2. The thiol-ene reaction with cysteamine or 3-mercaptopropionic acid and the trivinyl cluster leads to hexadentate ligands 3 × N-S or 3 × HOOC-S. The compounds were shown to effectively capture a variety of metals ions. Copper ion chelation was pursued in more detail, because of its toxicity. On average, metal ions form chelates with 2.4 of the three ligands in a cluster. Upon chelation, viscous oils are converted to (very) soft elastomers. Most of the ions could be stripped from the elastomers using aqueous EDTA solutions, demonstrating the ability of the silicones to both sequester and deliver ions. However, complete ion removal is not observed; at equilibrium, the silicones remain ionically crosslinked.

High Refractive Index, Enantiopure Silicones Based on BINOL.

The high refractive index aromatic compound, binaphthol (BINOL), is readily incorporated into silicone polymer chains using the Piers-Rubinsztajn (PR) reaction; alternating and random linear copolymers, and elastomers are available. The highest refractive index (RI) materials are BINOL rich. It is not possible to directly make high refractive index linear polymers with very short HSi-capped, telechelic silicone chains, as they do not react cleanly. However, chain extending short vinyl-capped BINOL macromers with simple arylsilanes using hydrosilylation leads to polymers with a molar mass of up to 8000 and refractive indices of up to 1.58. Elastomers are prepared using similar processes. The reactions are facile to practice and suggest BINOL can be harnessed in these and other processes to augment RI.

Differentiating Perpetrators of Intimate Partner Violence From Other Violent Offenders Using a Statistical Learning Model: The Role of Cognition and Life History Variables.

Intimate partner violence (IPV) is a widespread crime that victimizes over 4-million women per year in the United States and results in significant monetary cost and unmeasured physical and psychological consequences for victims. Specialized IPV offender treatment programs demonstrate limited effectiveness, which may be due to an insufficient understanding of the factors that differentiate between IPV perpetrators and non-IPV violent offenders. In this study, we utilized classification and regression tree (CART) analysis to identify combinations of factors that best discriminate IPV perpetrators from non-IPV violent offenders. We also compared cognitive abilities between IPV perpetrators and non-IPV violent offenders using standardized neurocognitive tests. CART analysis presented two pathways for identifying offenders as IPV perpetrators: (a) extensive nonviolent criminal history and (b) moderate-to-severe expression of interpersonal traits of psychopathy without attentional deficits. In addition, a third pathway identified non-IPV violent offenders: (c) low levels of interpersonal psychopathic traits and no history of neurodevelopmental diagnosis. IPV perpetrators demonstrated intact cognition relative to test norms, and study groups did not significantly differ on cognitive performance. These findings suggest that individuals with multiple arrests for nonviolent crime or individuals with interpersonal traits of psychopathy without attentional difficulties may be at enhanced risk for IPV perpetration.

Phonological processing in psychopathic offenders.

Recent research has demonstrated that psychopathic offenders exhibit dynamic cognitive and behavioral deficits on a variety of lab tasks that differentially activate left hemisphere resources. The Left Hemisphere Activation (LHA) hypothesis is a cognitive perspective that aims to address these deficits by conceptualizing psychopathy as a disorder in which behavior and cognitive processing change dynamically as a function of the differential taxation of left hemisphere resources. This study aimed to investigate whether psychopathic traits are associated with electrophysiological anomalies under conditions that place differential demands on left hemisphere language processing systems. We examined in a sample of 43 incarcerated indivdiuals the evocation of the N320, an event-related potential (ERP) elicited by nontarget stimuli during a phonological/phonetic decision task that has been shown to elicit greater activation and cognitive processing within the left hemisphere than the right hemisphere. Findings for a subsample of 18 offenders low in psychopathic traits were generally consistent with previous findings in healthy individuals, suggesting similar electrophysiological activity during phonological processing. However, psychopathic traits impacted the amplitude of the N320. Higher levels of psychopathic traits were associated with reduced left-lateralization in phonological processing as well as enhanced ERP differentiation between pronounceable and nonpronounceable stimuli. These findings provide physiological evidence of a relationship between psychopathic traits and anomalous language processing at the phonological level of word processing.

Naturally Derived Silicone Surfactants Based on Saccharides and Cysteamine.

Silicone surfactants are widely used in many industries and mostly rely on poly(ethylene glycol) (PEG) as the hydrophile. This can be disadvantageous because commercial PEG examples vary significantly in polydispersity-constraining control over surface activity of the surfactant-and there are environmental concerns associated with PEG. Herein, we report a three-step synthetic method for the preparation of saccharide-silicone surfactants using the natural linker, cysteamine, and saccharide lactones. The Piers-Rubinsztajn plus thiol-ene plus amidation process is attractive for several reasons: if employed in the correct synthetic order, it allows for precise tailoring of both hydrophobe and hydrophile; it permits the ready utilization of natural hydrophiles cysteamine and saccharides in combination with silicones, which have significantly better environmental profiles than PEG; and the products exhibit interesting surface activities.

Spatially Controlled Highly Branched Vinylsilicones.

Branched silicones possess interesting properties as oils, including their viscoelastic behavior, or as precursors to controlled networks. However, highly branched silicone polymers are difficult to form reliably using a "grafting to" strategy because functional groups may be bunched together preventing complete conversion for steric reasons. We report the synthesis of vinyl-functional highly branched silicone polymers based, at their core, on the ability to spatially locate functional vinyl groups along a silicone backbone at the desired frequency. Macromonomers were created and then polymerized using the Piers-Rubinsztajn reaction with dialkoxyvinylsilanes and telechelic HSi-silicones; molecular weights of the polymerized macromonomers were controlled by the ratio of the two reagents. The vinyl groups were subjected to iterative (two steps, one pot) hydrosilylation with alkoxysilane and Piers-Rubinsztajn reactions, leading to high molecular weight, highly branched silicones after one or two iterations. The vinyl-functional products can optionally be converted to phenyl/methyl-modified branched oils or elastomers.

When Attempting Chain Extension, Even Without Solvent, It Is Not Possible to Avoid Chojnowski Metathesis Giving D3.

A simple, mild and efficient method to prepare HSi- or HOSi-telechelic, high-molecular-weight polydimethylsiloxane polymers (to 41,600 g·mol-1) using the one-shot hydrolysis of MHMH is reported; titration of the water allowed for higher molecular weights (to 153,900 g·mol-1). The "living" character of the chain extension processes was demonstrated by adding a small portion of MHMH and B(C6F5)3 (BCF) to a first formed polymer, which led to a ~2-fold, second growth in molecular weight. The heterogeneous reaction reached completion in less than 30 min, much less in some cases, regardless of whether it was performed neat or 50 wt% in dry toluene; homogeneous reactions in toluene were much slower. The process does not involve traditional redistribution, as judged by the low quantities (<3%) of D4 produced. However, it is not possible to avoid Chojnowski metathesis from MHDDMH giving D3, which occurs competitively with chain extension.

Synergistic effect of carotenoid and silicone-based additives for photooxidatively stable organic solar cells with enhanced elasticity.

Photochemical and mechanical stability are critical in the production and application of organic solar cells. While these factors can individually be improved using different additives, there is no example of studies on the combined effects of such additive-assisted stabilization. In this study, the properties of PTB7:[70]PCBM organic solar cells are studied upon implementation of two additives: the carotenoid astaxanthin (AX) for photochemical stability and the silicone polydimethylsiloxane (PDMS) for improved mechanical properties. A newly designed additive, AXcPDMS, based on astaxanthin covalently bonded to PDMS was also examined. Lifetime tests, produced in ISOS-L-2 conditions, reveal an improvement in the accumulated power generation (APG) of 10% with pure AX, of 90% when AX is paired with PDMS, and of 140% when AXcPDMS is added in the active layer blend, as compared to the control devices. Singlet oxygen phosphorescence measurements are utilized to study the ability of AX and AXcPDMS to quench singlet oxygen and its precursors in the films. The data are consistent with the strong stabilization effect of the carotenoids. While AX and AXcPDMS are both efficient photochemical stabilizers, the improvement in device stability observed in the presence of AXcPDMS is likely due to a more favorable localization of the stabilizer within the blend. The mechanical properties of the active layers were investigated by tensile testing and cohesive fracture measurements, showing a joint improvement of the photooxidative stability and the mechanical properties, thus yielding organic solar cell devices that are promising for flexible photovoltaic applications.

Reversible Redox Crosslinking of Thiopropylsilicones.

Most silicone elastomers are thermosets. As a response to the new paradigm of polymer recyclability, the development of silicone elastomers that can be reversibly and repeatedly cured and uncrosslinked using redox conditions is reported. Thiopropyl-modified silicones are oxidized to elastomers with disulfide crosslinks using the organosoluble oxidant PhI(OAc)2 . As with any elastomer, mechanical properties can be tuned by varying crosslink density. Thermal stabilities in air show that the products are comparable to traditional silicone thermosets, with degradation only starting over 300 °C. Uncrosslinking back to the same thiopropyl-modified silicones involves reductive S-S bridge cleavage using a Piers-Rubinsztajn reaction with hydrosilanes catalyzed by B(C6 F5 )3 ; HSiMe2 OSiMe3 is identified as a convenient reducing agent. The initially formed silicone-(CH2 )3 S-SiMe2 OSiMe3 products need deprotection with water in isopropanol/water to completely regenerate the thiopropylsilicones. This oxidation/reduction crosslinking/uncrosslinking cycle is practiced thrice, with a yield of 89% per cycle, with essentially no change in the Young's moduli of the elastomers, or 1 H NMR spectra of the uncrosslinked fluids after reduction. Further oxidation of disulfide groups on the elastomer surface permanently and significantly improved water wettability.