Increased Donnan exclusion in charged polymer networks at high salt concentrations.

The swelling of univalent and multivalent charged polymeric networks in electrolytic solutions is studied using a classical thermodynamic model. Such systems were first modeled by Donnan, who derived an expression for the chemical potential of the ions by introducing an electric potential that is commonly referred to as the Donnan potential. This well-established theory leads to a simple quadratic relationship for the partitioning of ions between the network and the external solution. When the concentration of fixed charges in the swollen gel is large enough, the electrolyte in the external solution is "excluded" from the gel (commonly referred to as Donnan exclusion). In the standard Donnan theory, and in virtually all subsequent theories, the magnitude of Donnan exclusion decreases with increasing electrolyte concentration in the external solution. Our model predicts this is not necessarily true; we show that the magnitude of Donnan exclusion increases with increasing electrolyte concentration over a broad range of parameter space (average chain length between crosslinks, fraction of charged monomers in the network, the nature of the interactions between the ions, solvent molecules and polymer chains, and ion concentration in the external solution). We also present explicit bounds for the validity of Donnan's original theory. Model predictions are compared to simulations and experimental data obtained for a cationic gel immersed in electrolytic solutions of salts containing univalent and bivalent cations.

Programmable diode/resistor-like behavior of nanostructured vanadium pentoxide xerogel thin film.

Electrical properties of a Cr/V2O5/Cr structure are investigated and switching of the device due to electrochemical reactions is observed at low bias (<1 V). Depending on the polarity of the first applied bias, the switched device can behave like a diode (forward sweep first) or a resistor (reverse sweep first). The switching is irreversible and persistent, lasting for more than one month. By performing environmental tests, we prove that water molecules in the atmosphere and intercalated in the xerogel film are involved in the electrochemical reactions. It is proposed that an interfacial layer with reduced oxidation state forms at the Cr/V2O5 interface, and creates a higher Schottky barrier due to rise of electron affinity. Different interfacial layer thicknesses in forward and reverse first sweeps are responsible for different I-V characteristics in subsequent sweeps. The results suggest future applications of these V2O5 thin films in low-power read-only memory devices and diode-resistor networks.

A history of innovation: cardiac surgery in Minnesota.

For centuries, the heart was believed to be an inoperable organ. Through the development of new technologies and techniques, the initial difficulties inherent with operating on a moving organ began to fade. But as surgeons in the last century pushed the boundaries of cardiac repair, new problems arose. To solve them, they enlisted the help of physiologists, residents and engineers. By taking a multidisciplinary approach, sharing information and ideas, and working collaboratively, University of Minnesota and Mayo Clinic investigators found themselves at the forefront of cardiac surgery. This article reviews Minnesota's contributions to the field.

Stereotactic-guided direct orbital puncture for treatment of orbital arteriovenous fistula.

The patient presented with left-sided chemosis, exophthalmos, and progressive visual loss. Cerebral angiography ed a left orbital arteriovenous malformation and an associated hematoma, with the point of fistulation between the left ophthalmic artery and the anterior section of the inferior ophthalmic vein, with retrograde flow through the superior ophthalmic vein. Transvenous embolization through the anterior facial and angular veins was unsuccessful, with residual shunting. Stereotactic-guided direct venous puncture and Onyx embolization was subsequently performed in the hybrid operating room (OR) to cure the fistula. A subciliary incision allowed for retraction of the orbital contents, creating an optimal trajectory. An endonasal endoscopic approach was performed after the embolization to decompress the orbit. This procedure is shown in video 11-11 neurintsurg;16/4/429/V1F1V1Video 1 .

Core-shell catalysts consisting of nanoporous cores for oxygen reduction reaction.

A comprehensive experimental study was conducted on the dealloying of PdNi6 nanoparticles under various conditions. A two-stage dealloying protocol was developed to leach >95% of Ni while minimizing the dissolution of Pd. The final structure of the dealloyed particle was strongly dependent on the acid used and temperature. When H2SO4 and HNO3 solutions were used in the first stage of dealloying, solid and porous particles were generated, respectively. The porous particles have a 3-fold higher electrochemical surface area per Pd mass than the solid ones. The dealloyed PdNi6 nanoparticles were then used as a core material for the synthesis of core-shell catalysts. These catalysts were synthesized in gram-size batches and involved Pt displacement of an underpotentially deposited (UPD) Cu monolayer. The resulting materials were characterized by scanning transmission electron microscopy (STEM) and in situ X-ray diffraction (XRD). The oxygen reduction reaction (ORR) activity of the core-shell catalysts is 7-fold higher than the state-of-the-art Pt/C. The high activity was confirmed by a more than 40 mV improvement in fuel cell performance with a Pt loading of 0.1 mg cm(-2) by using the core-shell catalysts.

Surgeon Preference on Sending Routine Tonsillectomy Specimens for Pathological Evaluation.

INTRODUCTION: Despite the presence of a growing body of literature suggesting cost-ineffectiveness of routine pathologic analysis of tonsillectomy specimens, little is known about common institutional policies and practice patterns of pediatric otolaryngologists. The objectives of this study were to determine the prevalence of routine pathological evaluation of tonsillectomy specimens for uncomplicated pediatric adenotonsillectomy procedures and to evaluate opinions regarding this controversy among board-certified pediatric otolaryngologists. METHODS: This was a cross-sectional survey study sent to board-certified pediatric otolaryngologists currently practicing and registered with the American Society of Pediatric Otolaryngology (ASPO) assessing their institutions' or practices' current policies on sending routine tonsillectomy specimens for pathology, their experience with this practice, and their opinions on whether routine pathologic analysis should be employed. Basic statistical analysis was then conducted. RESULTS: Respondents mostly practiced in an academic setting (68.4%), with the next most common being academically affiliated private practice (21.8%), and private practice was the least common (9.8%). Most respondents (85.1%) did not agree with routine pathologic analysis of otherwise uncomplicated pediatric tonsillectomy specimens. CONCLUSION: Most pediatric otolaryngologists who responded to this survey do not support routine pathological analysis of otherwise uncomplicated pediatric tonsillectomy specimens. However, the results are likely biased and should be interpreted carefully, since only a small percentage of pediatric otolaryngologists responded to the survey. Potential cost savings could be seen by patients, payers, and hospital systems with judicious use of surgical pathology, specifically in cases with concurrent signs or symptoms suspicious for malignancy.

A dignitary medicine curriculum developed using a modified Delphi methodology.

BACKGROUND: Dignitary medicine is an emerging field of training that involves the specialized care of diplomats, heads of state, and other high-ranking officials. In an effort to provide guidance on training in this nascent field, we convened a panel of experts in dignitary medicine and using the Delphi methodology, created a consensus curriculum for training in dignitary medicine. METHODS: A three-round Delphi consensus process was performed with 42 experts in the field of dignitary medicine. Predetermined scores were required for an aspect of the curriculum to advance to the next round. The scores on the final round were used to determine the components of the curriculum. Scores below the threshold to advance were dropped in the subsequent round. RESULTS: Our panel had a high degree of agreement on the required skills needed to practice dignitary medicine, with active practice in a provider's baseline specialty, current board certification, and skills in emergency care and resuscitation being the highest rated skills dignitary medicine physicians need. Skills related to vascular and emergency ultrasound and quality improvement were rated the lowest in the Delphi analysis. No skills were dropped from consideration. CONCLUSIONS: The results of our work can form the basis of formal fellowship training, continuing medical education, and publications in the field of dignitary medicine. It is clear that active medical practice and knowledge of resuscitation and emergency care are critical skills in this field, making emergency medicine physicians well suited to practicing dignitary medicine.

Dignitary Medicine: A Novel Area of Medical Training.

Dignitary medicine (DM) involves the provision of healthcare to government leaders and other high-profile individuals collectively referred to as "dignitaries." Due to the unique circumstances around their lifestyle, dignitaries often receive suboptimal healthcare. We define the requisite skills needed to practice DM based on the available literature and provide a framework for training providers in these skills. A review of the English language medical literature focussing on adult subjects was performed, searching for terms such as "dignitary medicine," "VIP medicine," and "protective medicine." Literature was gathered from CINAHL, Google Scholar, PubMed, EBSCOHost, and San Bernardino County Library databases and then analyzed by experienced DM providers. A total of 23 relevant articles were eligible for review. No meta-analyses on the subject exist. We found that existing studies highlight skills in wellness, executive health, and protective medicine, which form the backbone of DM. The burgeoning field of DM encompasses several disciplines and skills. We strongly recommend a structured curriculum for the field of DM, focused on dignitary wellness, executive health, and protective medicine.

Novel 10-Bit Impedance-to-Digital Converter for Electrochemical Impedance Spectroscopy Measurements.

Electrochemical impedance spectroscopy (EIS) is a widely used technique in biomedical and chemical analysis. A novel 10-bit impedance-to-digital converter (IDC), which can measure and directly convert the magnitude and phase of impedance to digital codes, is proposed for the EIS measurement system. The proposed IDC is composed of a magnitude-to-digital converter (MDC) and a phase-to-digital converter (PDC). The proposed IDC was designed and fabricated using a 0.35 [Formula: see text] 2P4M mixed-signal polycide process, and the core area is only 0.07 mm2. Moreover, it can work over a very wide frequency range (0.1 mHz-100 kHz), and has excellent accuracy. According to the measured results, the DNL of the MDC is within -0.3/+0.3 LSB, and the INL is around -3/+1 LSB. Moreover, an EIS measurement system, which is composed of the proposed IDC chip and some other commercial chips, is built to measure ZoBell's and melatonin solutions for validating the function of the proposed IDC.

A multiparameter wearable physiologic monitoring system for space and terrestrial applications.

A novel, unobtrusive and wearable, multiparameter ambulatory physiologic monitoring system for space and terrestrial applications, termed LifeGuard, is presented. The core element is a wearable monitor, the crew physiologic observation device (CPOD), that provides the capability to continuously record two standard electrocardiogram leads, respiration rate via impedance plethysmography, heart rate, hemoglobin oxygen saturation, ambient or body temperature, three axes of acceleration, and blood pressure. These parameters can be digitally recorded with high fidelity over a 9-h period with precise time stamps and user-defined event markers. Data can be continuously streamed to a base station using a built-in Bluetooth RF link or stored in 32 MB of on-board flash memory and downloaded to a personal computer using a serial port. The device is powered by two AAA batteries. The design, laboratory, and field testing of the wearable monitors are described.

The history and threat of biological warfare and terrorism.

The inevitable conclusion is that the availability of biological warfare agents and supporting technologic infrastructure, coupled with the fact that there are many people motivated to do harm to the United States, means that America must be prepared to defend her homeland against biological agents. Some have argued to the contrary, that the threat and risks from a biological weapon attack are not to be considered serious, because [39]: They've not been used yet on a large scale so they probably won't be in the near future. Their use is so morally repugnant that they probably won't be used at all. The technologic hurdles associated with isolating, growing, purifying, weaponizing, and disseminating adequate quantities of pathologic agents are so high that only the most advanced laboratories could attempt the process. Similar to a 'nuclear winter,' the aftermath of a biological attack is so unthinkable that none would attempt it. Unfortunately, the trends associated with biotechnology globalization, terrorist group dynamics, and global/regional politics render these beliefs untenable and inappropriate, as recent events have underscored. To that end, the United States has accelerated its program of defense against biological weapons, as it must. Biological weapons are such dreadful weapons of uniqueness and complexity that a specific defense strategy is paramount. Elements of this program include pharmaceutical stockpiles, heightened surveillance systems, energized vaccine development programs, and comprehensive training initiatives. Although the depth and breadth of these efforts are unprecedented, above all these efforts is the absolute necessity for medical and public health care professionals to be educated and actively involved. These professionals are the sine qua non of future defensive readiness. This is just the start; unfortunately, there is no end yet in sight.

Threats in bioterrorism. I: CDC category A agents.

Although once considered unlikely, bioterrorism is now a reality in the United States since the anthrax cases began appearing in the fall of 2001. Intelligence sources indicate there are many countries and terrorist organizations that either possess biological weapons or are attempting to procure them. In the future it is likely that we will experience additional acts of bioterrorism. The CDC category A agents represent our greatest challenge because they have the potential to cause grave harm to the medical and public health systems of a given population. Thus, it is imperative that plans be developed now to deal with the consequences of an intentional release of any one or more of these pathogens.

The value of routine pH monitoring in the diagnosis and treatment of laryngopharyngeal reflux.

OBJECTIVE: To assess the need for pH testing in diagnosing laryngopharyngeal reflux (LPR). STUDY DESIGN: Case series with planned data collection. SETTING: Tertiary care center. SUBJECTS AND METHODS: On the basis of symptoms and/or abnormal endoscopic findings, more than 500 patients underwent 24-hour pharyngeal pH testing at a single center (using the Dx-pH probe) between January 2009 and June 2011. A total of 163 patients not on proton-pump inhibitors at the time of study and with complete data available for analysis (pH results, body mass index, smoking status, pretest reflux symptom index) were divided into 2 groups by positive (n = 70) and negative (n = 93) Ryan Score. The Reflux Symptom Index (RSI) was compared between groups and assessed overall against Ryan Score parameters at different pH thresholds. The diagnostic utility of an RSI ≥ 13 for prediction of Ryan Score was assessed. RESULTS: No significant difference in RSI was seen between Ryan-positive (17.50 ± 11.47) and Ryan-negative (14.95 ± 11.43) patients (P = .161). Overall, RSI correlated poorly with percentage time spent below pH thresholds 6.5, 6.0, 5.5, and 5.0 and upright and supine Ryan parameters at these thresholds (as determined by linear regression analysis). The sensitivity, specificity, positive predictive value, and negative predictive value of RSI ≥ 13 for Ryan positivity were 55.7%, 47.3%, 44.3%, and 58.7%, respectively. CONCLUSION: Our findings show that in our population of otolaryngology patients, the diagnosis of LPR cannot be reliably made on the basis of symptoms alone. Diagnosis, and in particular treatment decisions, should ideally be made on the basis of a combination of symptoms, signs, and confirmatory testing.

Smart pixel optical sensor based on positive optical feedback.

A smart pixel optical sensor based on positive optical feedback is described and demonstrated. The scheme uses the reflectance of an external scene as part of the positive feedback loop and uses the nonlinear characteristics of a vertical-cavity surface-emitting laser to obtain bistability and hysteresis. As a result, the continuous reflectance variation of the scene is mapped to a digital output with increased noise immunity for each pixel of the array.