A Single-Ion Conducting Borate Network Polymer as a Viable Quasi-Solid Electrolyte for Lithium Metal Batteries

Lithium-ion batteries have remained a state-of-the-art electrochemical energy storage technology for decades now, but their energy densities are limited by electrode materials and conventional liquid electrolytes can pose significant safety concerns. Lithium metal batteries featuring Li metal anodes, solid polymer electrolytes, and high-voltage cathodes represent promising candidates for next-generation devices exhibiting improved power and safety, but such solid polymer electrolytes generally do not exhibit the required excellent electrochemical properties and thermal stability in tandem. Here, an interpenetrating network polymer with weakly coordinating anion nodes that functions as a high-performing single-ion conducting electrolyte in the presence of minimal plasticizer, with a wide electrochemical stability window, a high room-temperature conductivity of 1.5 × 10^-4 S cm^-1 , and exceptional selectivity for Li-ion conduction (t_Li+ = 0.95) is reported. Importantly, this material is also flame retardant and highly stable in contact with lithium metal. Significantly, a lithium metal battery prototype containing this quasi-solid electrolyte is shown to outperform a conventional battery featuring a polymer electrolyte.

Near-Perfect CO2/CH4 Selectivity Achieved through Reversible Guest Templating in the Flexible Metal-Organic Framework Co(bdp)

Metal-organic frameworks are among the most promising materials for industrial gas separations, including the removal of carbon dioxide from natural gas, although substantial improvements in adsorption selectivity are still sought. Herein, we use equilibrium adsorption experiments to demonstrate that the flexible metal-organic framework Co(bdp) (bdp^2- = 1,4-benzenedipyrazolate) exhibits a large CO₂ adsorption capacity and approaches complete exclusion of CH₄ under 50:50 mixtures of the two gases, leading to outstanding CO₂/CH₄ selectivity under these conditions. In situ powder X-ray diffraction data indicate that this selectivity arises from reversible guest templating, in which the framework expands to form a CO₂ clathrate and then collapses to the nontemplated phase upon desorption. Under an atmosphere dominated by CH₄, Co(bdp) adsorbs minor amounts of CH₄ along with CO₂, highlighting the importance of studying all relevant pressure and composition ranges via multicomponent measurements when examining mixed-gas selectivity in structurally flexible materials. Altogether, these results show that Co(bdp) may be a promising CO₂/CH₄ separation material and provide insights for the further study of flexible adsorbents for gas separations.

Engineered Transport in Microporous Materials and Membranes for Clean Energy Technologies

Many forward-looking clean-energy technologies hinge on the development of scalable and efficient membrane-based separations. Ongoing investment in the basic research of microporous materials is beginning to pay dividends in membrane technology maturation. Specifically, improvements in membrane selectivity, permeability, and durability are being leveraged for more efficient carbon capture, desalination, and energy storage, and the market adoption of membranes in those areas appears to be on the horizon. Herein, an overview of the microporous materials chemistry driving advanced membrane development, the clean-energy separations employing them, and the theoretical underpinnings tying membrane performance to membrane structure across multiple length scales is provided. The interplay of pore architecture and chemistry for a given set of analytes emerges as a critical design consideration dictating mass transport outcomes. Opportunities and outstanding challenges in the field are also discussed, including high-flux 2D molecular-sieving membranes, phase-change adsorbents as performance-enhancing components in composite membranes, and the need for quantitative metrologies for understanding mass transport in heterophasic materials and in micropores with unusual chemical interactions with analytes of interest.

Diamine-Appended Mg2(dobpdc) Nanorods as Phase-Change Fillers in Mixed-Matrix Membranes for Efficient CO2/N2 Separations

Despite the availability of chemistries to tailor the pore architectures of microporous polymer membranes for chemical separations, trade-offs in permeability and selectivity with functional group manipulations nevertheless persist, which ultimately places an upper bound on membrane performance. Here we introduce a new design strategy to uncouple these attributes of the membrane. Key to our success is the incorporation of phase-change metal-organic frameworks (MOFs) into the polymer matrix, which can be used to increase the solubility of a specific gas in the membrane, and thereby its permeability. We further show that it is necessary to scale the size of the phase-change MOF to nanoscopic dimensions, in order to take advantage of this effect in a gas separation. Our observation of an increase in solubility and permeability of only one of the gases during steady-state permeability measurements suggests fast exchange between free and chemisorbed gas molecules within the MOF pores. While the kinetics of this exchange in phase-change MOFs are not yet fully understood, their role in enhancing the efficacy and efficiency of the separation is clearly a compelling new direction for membrane technology.

Enhanced ethylene separation and plasticization resistance in polymer membranes incorporating metal-organic framework nanocrystals

The implementation of membrane-based separations in the petrochemical industry has the potential to reduce energy consumption significantly relative to conventional separation processes. Achieving this goal, however, requires the development of new membrane materials with greater selectivity, permeability and stability than available at present. Here, we report composite materials consisting of nanocrystals of metal-organic frameworks dispersed within a high-performance polyimide, which can exhibit enhanced selectivity for ethylene over ethane, greater ethylene permeability and improved membrane stability. Our results suggest that framework-polymer interactions reduce chain mobility of the polymer while simultaneously boosting membrane separation performance. The increased stability, or plasticization resistance, is expected to improve membrane utility under real process conditions for petrochemical separations and natural gas purification. Furthermore, this approach can be broadly applied to numerous polymers that encounter aggressive environments, potentially making gas separations possible that were previously inaccessible to membranes.

Application of a high-throughput analyzer in evaluating solid adsorbents for post-combustion carbon capture via multicomponent adsorption of CO2, N2, and H2O

Despite the large number of metal-organic frameworks that have been studied in the context of post-combustion carbon capture, adsorption equilibria of gas mixtures including CO2, N2, and H2O, which are the three biggest components of the flue gas emanating from a coal- or natural gas-fired power plant, have never been reported. Here, we disclose the design and validation of a high-throughput multicomponent adsorption instrument that can measure equilibrium adsorption isotherms for mixtures of gases at conditions that are representative of an actual flue gas from a power plant. This instrument is used to study 15 different metal-organic frameworks, zeolites, mesoporous silicas, and activated carbons representative of the broad range of solid adsorbents that have received attention for CO2 capture. While the multicomponent results presented in this work provide many interesting fundamental insights, only adsorbents functionalized with alkylamines are shown to have any significant CO2 capacity in the presence of N2 and H2O at equilibrium partial pressures similar to those expected in a carbon capture process. Most significantly, the amine-appended metal organic framework mmen-Mg2(dobpdc) (mmen = N,N'-dimethylethylenediamine, dobpdc (4-) = 4,4'-dioxido-3,3'-biphenyldicarboxylate) exhibits a record CO2 capacity of 4.2 ± 0.2 mmol/g (16 wt %) at 0.1 bar and 40 °C in the presence of a high partial pressure of H2O.

Fe electron transfer and atom exchange in goethite: influence of Al-substitution and anion sorption

The reaction of Fe(II) with Fe(III) oxides and hydroxides is complex and includes sorption of Fe(II) to the oxide, electron transfer between sorbed Fe(II) and structural Fe(III), reductive dissolution coupled to Fe atom exchange, and, in some cases mineral phase transformation. Much of the work investigating electron transfer and atom exchange between aqueous Fe(II) and Fe(III) oxides has been done under relatively simple aqueous conditions in organic buffers to control pH and background electrolytes to control ionic strength. Here, we investigate whether electron transfer is influenced by cation substitution of Al(III) in goethite and the presence of anions such as phosphate, carbonate, silicate, and natural organic matter. Results from (57)Fe Mössbauer spectroscopy indicate that both Al-substitution (up to 9%) and the presence of common anions (PO(4)(3-), CO(3)(2-), SiO(4)(4-), and humic acid) does not inhibit electron transfer between aqueous Fe(II) and Fe(III) in goethite under the conditions we studied. In contrast, sorption of a long-chain phospholipid completely shuts down electron transfer. Using an enriched isotope tracer method, we found that Al-substitution in goethite (10%), does, however, significantly decrease the extent of atom exchange between Fe(II) and goethite (from 43 to 12%) over a month's time. Phosphate, somewhat surprisingly, appears to have little effect on the rate and extent of atom exchange between aqueous Fe(II) and goethite. Our results show that electron transfer between aqueous Fe(II) and solid Fe(III) in goethite can occur under wide range of geochemical conditions, but that the extent of redox-driven Fe atom exchange may be dependent on the presence of substituting cations such as Al.

Inhibition of trace element release during Fe(II)-activated recrystallization of Al-, Cr-, and Sn-substituted goethite and hematite

Aqueous Fe(II) reacts with Fe(III) oxides by coupled electron transfer and atom exchange (ETAE) resulting in mineral recrystallization, contaminant reduction, and trace element cycling. Previous studies of Fe(II)-Fe(III) ETAE have explored the reactivity of either pure iron oxide phases or those containing small quantities of soluble trace elements. Naturally occurring iron oxides, however, contain substantial quantities of insoluble impurities (e.g., Al) which are known to affect the chemical properties of such minerals. Here we explore the effect of Al(III), Cr(III), and Sn(IV) substitution (1-8 mol %) on trace element release from Ni(II)-substituted goethite and Zn(II)-substituted hematite during reaction with aqueous Fe(II). Fe(II)-activated trace element release is substantially inhibited from both minerals when an insoluble element is cosubstituted into the structure, and the total amount of release decreases exponentially with increasing cosubstituent. The limited changes in surface composition that occur following reaction with Fe(II) indicate that Al, Cr, and Sn do not exsolve from the structure and that Ni and Zn released to solution originate primarily from the bulk rather than the particle exterior (upper ~3 nm). Incorporation of Al into goethite substantially decreases the amount of iron atom exchange with aqueous Fe(II) and, consequently, the amount of Ni release from the structure. This implies that trace element release inhibition caused by substituting insoluble elements results from a decrease in the amount of mineral recrystallization. These results suggest that naturally occurring iron oxides containing insoluble elements are less susceptible to Fe(II)-activated recrystallization and exhibit a greater retention of trace elements and contaminants than pure mineral phases.

Educational achievement and pain disability among women with chronic pelvic pain

OBJECTIVE

This study examined the relationship of level of educational (LOE) achievement to pain experience, affective disturbance, and perceived disability among women with chronic pelvic pain presenting for pain treatment.

METHODS

187 patients completed a battery of self-report inventories assessing pain, psychological status, and functional ability. Educational attainment was stratified across five levels from "less than high school" to "graduate/professional school."

RESULTS

Significant inverse associations were found between lower educational achievement and more severe pain, somatic preoccupation, emotional suffering and guardedness, and functional impairment. No differences were obtained across the groups for age, duration of pain, or symptoms of depression.

CONCLUSIONS

These data provide support for the importance of socioeconomic factors, particularly LOE, in furthering our understanding of the morbidity observed among women suffering chronic pelvic pain.

Use of the McGill Pain Questionnaire to compare women with vulvar pain, pelvic pain and headaches

OBJECTIVE

To assess differences between women with three distinct types of chronic pain conditions using a modified McGill Pain Questionnaire.

STUDY DESIGN

Data by self-administered questionnaire were collected on patients presenting to the University of Michigan Medical Center with chronic vulvar pain (144 patients), pelvic pain (198 patients) or headaches (130 patients). Data for analysis included: patient demographics, duration of pain and modified McGill Pain Questionnaire scores. Univariate and multivariate analyses were performed.

RESULTS

Patients with vulvar pain had more formal education (P < .001), were more likely to be married (P < .001) and were less likely to be African American (P = .003) as compared to those with chronic pelvic pain and headaches. Chronic pelvic pain patients were younger than those in the other two groups (P = .002), and headache patients were likely to have had their chronic pain for a shorter duration than those with vulvar or pelvic pain (P < .001). Patients with vulvar pain had lower total scores on the McGill Pain Questionnaire as well as on the four subsets of variables: affective, sensory, cognitive and miscellaneous indexes (P < .001). They also chose fewer words to describe their symptoms from the 20-word lists (P < .001) and had lower average scores in each of the 20 categories as compared to the other two groups (P < .0001). Controlling for age, ethnicity and marital status did not alter this significance.

CONCLUSION

Patients with vulvar pain were a unique groups when compared to other chronic pain populations. Evaluation of the demographics and McGill Pain Questionnaire scores confirmed the distinct qualities of women with vulvar pain.

Chronic myofascial pain: knowledge of diagnosis and satisfaction with treatment

OBJECTIVE

To examine the relation between pain patients' knowledge of pain diagnosis and their satisfaction with pain treatment. It was hypothesized that myofascial pain (MP) patients would be less knowledgeable regarding their diagnosis and less satisfied with the results of pain treatment.

DESIGN

Cross-sectional.

SETTING

Multidisciplinary pain clinic.

PATIENTS

Patients (n=65) were divided into two groups after multidisciplinary assessment: MP patients (n=30) and a mixed group of chronic pain patients (MCP) (n=35) with neurologic or rheumatologic disorders.

MAIN OUTCOME MEASURES

Patient self-report of their knowledge of pain diagnosis and scores on standardized measures of pain intensity, depressive symptoms, and functional disability.

RESULTS

MP patients were significantly less accurate in identifying their diagnosis and the source of their pain and were more likely to believe they suffered a physiologic disturbance "more serious and different" than their physicians had suggested. MP patients were also significantly more dissatisfied with the treatment for pain by physicians and reported particular dissatisfaction with the informational aspects of physician-patient communication. No group differences were obtained for measures of pain severity, depression, disability, pain duration, or compensation/litigation status.

CONCLUSION

MP patients appear to have less accurate beliefs regarding their pain symptoms and express more dissatisfaction with physician efforts to treat their pain. These findings emphasize the importance of patient education as a component of chronic pain intervention, particularly for MP patients.

The relationship between symptoms of post-traumatic stress disorder and pain, affective disturbance and disability among patients with accident and non-accident related pain

Recent studies have reported a high prevalence of symptoms of post-traumatic stress disorder (PTSD) among individuals with chronic pain. Studies suggest that persons with pain and PTSD also display higher levels of affective disturbance. In the present study we examined self-reports of pain, affective disturbance, and disability among pain patients with and without symptoms of PTSD. Patients without PTSD symptoms were further subdivided into persons whose pain was the result of an accident or insidious in onset. Thus, three groups were examined: (1) persons with accident related pain and high PTSD symptoms (Accident/High PTSD); (2) persons with no or few symptoms of PTSD whose pain was accident related (Accident/Low PTSD); and (3) patients whose pain was not accident related and did not have PTSD symptoms (No Accident). No Accident patients were older than persons with accident related injuries, and both accident related pain groups were more likely than No Accident patients to be involved in litigation or receiving compensation. Thus, these variables were controlled for in the statistical analyses. Self-report of pain was also included as a covariate in the analyses examining group differences in affective disturbance and disability. Accident/High PTSD patients displayed higher levels of self-reported pain compared to the other two groups. The Accident/High PTSD group also had the highest levels of affective disturbance. Both accident groups tended to report greater disability compared to patients whose pain was not accident related. These findings suggest that PTSD symptoms in chronic pain patients are associated with increased pain and affective distress. Accident related pain, even without the presence of PTSD symptoms, appears to be associated with greater disability. The results indicate that the identification and treatment of PTSD symptoms in refractory pain patients may be a critical albeit subtle factor in the effective management of suffering and disability in this population.

Management of inappropriate behaviors of trainable mentally impaired students using antecedent exercise

The effects of several levels of exercise on inappropriate behaviors of four trainable mentally impaired students were observed. Treatment conditions, which occurred as the first daily activity, included: Phase I, daily alternating conditions of warm-up exercises and jogging at a moderate rate for a short distance; Phase II, daily alternating conditions of no-exercise periods and jogging at a vigorous rate for a moderate distance; and Phase III, jogging at a vigorous rate for a moderate distance on consecutive days. For one student two additional conditions occurred, Phase IV, long-distance jogging on consecutive days at a vigorous rate and Phase V, consecutive days of no exercise. Observations of three inappropriate behaviors of each student occurred immediately after, 1 hour after, and 2 hours after each exercise period. Results indicate a decrease in all three inappropriate behaviors for three of four students and an inverse relationship between the level of exercise and the amount of inappropriate behavior for three of four students. Improvements over existing studies are discussed with suggestions for future research.