Yield stress of pretreated corn stover suspensions using magnetic resonance imaging.

Cellulose fibers in water form networks that give rise to an apparent yield stress, especially at high solids contents. Measuring the yield stress and correlating it with fiber concentration is important for the biomass and pulp industries. Understanding how the yield stress behaves at high solids concentrations is critical to optimize enzymatic hydrolysis of biomass in the production of biofuels. Rheological studies on pretreated corn stover and various pulp fibers have shown that yield stress values correlate with fiber mass concentration through a power-law relationship. We use magnetic resonance imaging (MRI) as an in-line rheometer to measure velocity profiles during pipe flow. If coupled with pressure drop measurements, these allow yield stress values to be determined. We compare our results with literature values and discuss the accuracy and precision of the rheo-MRI measurement, along with the effects of fiber characteristics on the power-law coefficients.

Shared Medical Appointments in Preoperative Joint Replacement: Assessing Patient and Healthcare Member Satisfaction.

BACKGROUND: Shared medical appointments (SMAs) have proven to be effective in improving patient access and education while augmenting productivity. In shifting from a traditional visit model, patient and interdisciplinary healthcare team (IHCT) member satisfaction is imperative. Predominantly seen in primary care, SMA use in orthopedics is limited. After identification of access and productivity concerns, the SMA was implemented as a quality improvement project in a rural clinic. The lower extremity joint replacement (LEJR) population was chosen because of multiple preoperative appointments and costs on the healthcare system. PURPOSE: To assess patients' and IHCT members' satisfaction levels in using an SMA for the preparation of LEJR. RELEVANCE TO HEALTHCARE QUALITY: The SMA is an effective model offering an efficient, cost-effective methodology aligning with the Institute for Healthcare Improvement's Triple Aim. RESULTS: Twenty SMAs were conducted. Sixty-three patients and 14 ICHT members participated. Mean (M) satisfaction rating for SMA patients (M = 4.90, SD 0.26) was significantly higher than mean for traditional patients (M = 4.03, SD 0.39). Interdisciplinary healthcare team members' attitudes toward SMAs revealed a mean score of 4.58. Incidentally, cycle times improved as did lengths of stay. CONCLUSIONS: Lower extremity joint replacement patients and IHCT members reported high satisfaction with SMAs.

Needle size and injection rate impact microbubble contrast agent population.

The most common type of ultrasound contrast agents are encapsulated microbubbles, typically 1 to 5 microns in diameter. These microbubbles are injected into the bloodstream to provide image enhancement during an ultrasound examination. Because of their compressibility, these microbubbles are inherently sensitive to changes in pressure. For imaging, this is beneficial in that these microbubbles oscillate in an acoustic field and allow imaging systems to detect their response uniquely from tissue. However, this sensitivity also means that microbubbles can be readily destroyed by significant hydrostatic pressure. Injection of these microbubbles through a small-gauge catheter, such as is sometimes performed in small animal imaging studies, can result in microbubble destruction. In this manuscript, the effects of microbubble injection through catheters of varying diameter are examined. Our results indicate that the concentration and size distribution of microbubbles can be substantially altered in cases of rapid injection through small-gauge needles.

Interfacial and stability study of microbubbles coated with a monostearin/monopalmitin-rich food emulsifier and PEG40 stearate.

The stability and presence of micron-scale bubbles (microbubbles) is of considerable interest in environmental, biomedical, and food sciences. Here we show that microbubbles can be formed and stabilized in a solution of low cost food-grade emulsifier (a mixture of saturated long-chain monoglycerides, diglycerides and sodium stearoyl-2-lactylate) in combination with polyethylene glycol (PEG)-40 stearate. Langmuir trough methods and fluorescence microscopy were combined to investigate the surface tension, interfacial elastic modulus, phase behavior and microstructure of monolayer shells coating these microbubbles. Our results strongly suggest that although the PEG40S is necessary to form microbubbles this component, as well as sodium stearoyl-2-lactylate, are "squeezed out" in the form of collapse aggregates. This process leaves a microbubble shell, composed of a condensed-phase low surface tension mono- and diglycerides mixture with some of the PEG40S and SSL2 remaining trapped between the condensed-phase domains. We find that other commercially available emulsifiers, containing unsaturated or bulky components unable to form condensed phases, do not to form or stabilize a microbubble layer, although they may form a foam, a finding that we relate to differences in surface tension.

Surgical considerations in cystic fibrosis: a 32-year evaluation of outcomes.

BACKGROUND: Information concerning long-term operative outcomes in patients with cystic fibrosis (CF) is relatively sparse in the operative literature. METHODS: A retrospective review of CF patients with operative conditions was performed (1972-2004) at a tertiary children's hospital to analyze outcomes including long-term morbidity and survival. RESULTS: A total of 226 patients with CF presented with an operative diagnosis (113 men, 113 women). A total of 422 operations were performed in 213 patients (94%). The mean age at operation was 4.1 +/- 6.2 years (range, 1 d to 26 y) and 109 were neonates. Fifteen of 42 (36%) babies with simple meconium ileus (MI) were treated nonoperatively with hypertonic enemas, 27 of 42 and all 45 patients with complicated MI required operation, including 15 with jejunoileal atresia (17%). Seventeen of 27 (63%) patients with meconium ileus equivalent had MI as neonates; 7 of 27 (26%) required operation. Eight of 9 (89%) with fibrosing colonopathy required operation. Organ transplantation was required in 21 patients. Follow-up evaluation was possible in 204 of 213 (96%) patients. The duration of follow-up evaluation was 14.9 +/- 8.5 years (range, 2 mo to 35 y). Operative morbidity was 11% at 1 year, 2% at 2 to 4 years, 1% at 5 to 10 years, and less than 1% at more than 10 years. There were 24 deaths (11%); 22 followed CF-related pulmonary complications and included 8 of 16 (50%) children with pneumothorax. CONCLUSIONS: Long-term survival in CF patients has improved significantly (89%), with many surviving into the fourth decade. MI may predispose to late complications including meconium ileus equivalent and fibrosing colonopathy. Pneumothorax in CF patients is an ominous predictor of mortality. Children with CF are living longer and are good candidates for operation, but require long-term follow-up evaluation because of ongoing exocrine dysfunction.

The effect of mixing on the liquefaction and saccharification of cellulosic fibers.

The enzymatic hydrolysis of cellulosic material is a key step in the biochemical routes for production of renewable fuels and chemicals. This must be performed at high solids to be economically viable. High solids operations creates numerous processing challenges, most importantly the limitations due to mass transfer and poor mixing of enzymes in the cellulose suspensions. We use magnetic resonance imaging (MRI), a cylindrical penetrometer, and HPLC to demonstrate the importance of spatial homogeneity in the distribution of enzyme on the rates of liquefaction of the substrate and in the suspension mechanical strength. Our results show that the largest mechanical strength changes occur in a narrow interval of time during the initial stages of conversion. Differences in enzyme concentration distribution occurring at the centimeter-scale produced order of magnitude differences in liquefaction and saccharification rates, supporting the hypothesis that mixing quality has a major influence in both liquefaction and saccharification rates.

Influence of the dissolution rate on the collapse and shedding behavior of monostearin/monopalmitin-rich coated microbubbles.

A low cost food grade emulsifier (a mixture of monoglycerides, diglycerides, and sodium stearoyl lactylate) in combination with polyethylene glycol-40 stearate (PEG-40S) was used as an alternative to pure saturated phospholipids to form the thin shell of a microbubble. To investigate the stability of these microbubbles in a water system over time, their dissolution behavior was studied at various degas factors and at two percentages of PEG-40S. It was found that the favored shell collapse/shedding mechanism switched, as the dissolution rate increased (degas factor decreased), from folding with a smooth surface contour to buckling accompanied by surface folding/expulsion with a cyclic buckled-smooth surface contour. The compositional change that we made played a more minor role, mainly controlling the resistance to mass transfer of the microbubble shell and again modifying the mechanism-determinant dissolution rate. The shell resistance behavior for these microbubbles varied from that of previous lipid/PEG-40S-coated microbubbles by the presence of a maximum in shell resistance during dissolution. We hypothesize that the dominance of one collapse mechanism over another for these compositions is related to the time scales of two competing processes, fold nucleation and area compression. For these mixtures at room temperature, we estimate that the maximum area compression rate for folding as the major collapse mechanism is approximately 0.2 s (-1), a rate unattainable in a traditional Langmuir trough but achievable by the use of a dissolving microbubble.

Stability and rheological behavior of concentrated monodisperse food emulsifier coated microbubble suspensions.

Nearly monodispersed populations of microbubbles were produced using flow focusing with a food grade emulsifier. The microbubbles produced by this technique have diameters in the range of 120-200 microm. The flow focusing device uses metered streams of air and liquid to produce a jet that periodically pinches to make individual microbubbles. The size of the microbubbles can be controlled by changing the relative flow rates of the gas and the liquid. The emulsifier consists of a mixture of monoglycerides, diglycerides and sodium stearoyl lactylate in combination with polyethylene glycol (PEG)-40 stearate. The emulsifier forms a thin shell that stabilizes the microbubbles. The microbubbles are stable over time with their sizes remaining roughly constant over 2 h. Such stability allows suspensions of microbubbles to be formed and their rheological properties tested. The sizes of the microbubbles are also monitored off-line while testing, examining the effect of shearing on the bubble sizes, as well as their stability over time. These results show that the microbubble suspensions are viscoelastic and exhibit power law behavior. The relationship between the air fraction of the suspension and fluid viscosity is determined.

Maintaining monodispersity in a microbubble population formed by flow-focusing.

The dynamic processes impacting the size distributions of lipid-encapsulated microbubbles formed by flow-focusing were observed by video optical microscopy. Parameters studied included the filling gas, gas saturating the surrounding solution, and microbubble size (initial size 2-12 microm) to simulate typical laboratory conditions. Typically, dissolution or growth, followed by Ostwald ripening at a collection cover glass, were observed and quantified. However, in the case of small nitrogen-filled microbubbles surrounded by an air-saturated solution, Ostwald ripening was avoided for at least 9 h. These bubbles had a final size distribution of 1.5 +/- 0.1 microm. This work suggests that lipid-encapsulated microbubbles formed by flow-focusing should be given sufficient time to reach a terminal size before coming into contact with each other. These long-lived mondisperse microbubbles should be of interest in ultrasound contrast agents, microfabrication, food, and research applications.

Tailoring the size distribution of ultrasound contrast agents: possible method for improving sensitivity in molecular imaging.

Encapsulated microbubble contrast agents incorporating an adhesion ligand in the microbubble shell are used for molecular imaging with ultrasound. Currently available microbubble agents are produced with techniques that result in a large size variance. Detection of these contrast agents depends on properties related to the microbubble diameter such as resonant frequency, and current ultrasound imaging systems have bandwidth limits that reduce their sensitivity to a polydisperse contrast agent population. For ultrasonic molecular imaging, in which only a limited number of targeted contrast agents may be retained at the site of pathology, it is important to optimize the sensitivity of the imaging system to the entire population of contrast agent. This article presents contrast agents with a narrow size distribution that are targeted for molecular imaging applications. The production of a functionalized, lipid-encapsulated, microbubble contrast agent with a monodisperse population is demonstrated, and we evaluate parameters that influence the size distribution and demonstrate initial acoustic testing.

Long-term stability by lipid coating monodisperse microbubbles formed by a flow-focusing device.

In this letter, the long-term stabilization of monodisperse microbubbles produced by flow focusing is demonstrated using lipid encapsulation. Fluorescence microscopy, high-speed camera imaging, and particle size analysis were used to investigate the roles of lipid phase behavior, dissolution, Ostwald ripening, and coalescence in the stability of microbubbles formed by flow focusing. It was found that these behaviors were controlled through compositional changes with respect to lipid, emulsifier, and viscosity agents. Microbubbles coated with lipid and PEG emulsifier in a viscous solution were found to contain an extremely narrow size distribution (diameter(av) = 51 microm, standard deviation = 4 microm), which was maintained for up to several months.

Long-term outcomes in patients with stage IV neuroblastoma.

AIM OF STUDY: Long-term outcome studies in survivors with stage IV neuroblastoma (NB) are sparse. This review evaluates late complications and long-term outcomes in stage IV NB survivors. METHODS: A retrospective review of stage IV NB survivors was performed to analyze outcomes, including long-term morbidity, recurrence, and survival. MAIN RESULTS: Of 153 patients with stage IV NB, 52 (34%) survived (male-female, 26:26). Age at diagnosis was 29.1 +/- 31.7 months in survivors. Eighteen were 1 year or younger and 34 were older than 1 year compared with 10 nonsurvivors 1 year or younger and 91 older than 1 year (P = .0003, Fisher's Exact test). Primary tumor sites were adrenal (35), retroperitoneal (11), mediastinal (3), pelvic (2), and no primary with tumor metastases identified (1). Ten survivors had favorable and 16 had unfavorable histology compared with 1 favorable and 18 unfavorable in nonsurvivors (P = .01). Four survivors had MYCN amplification (> or = 10 copies) and 2 deletions of 1p and 11q. Sites of metastasis in survivors and nonsurvivors were similar. Treatment in survivors included surgery in 51 (75% [39/51] complete tumor resection [CTR]); chemotherapy, 50; radiation, 17; stem cell transplantation, 20; and bone marrow transplant, 1. In nonsurvivors, 13 (25%) of 53 (P < < .0001) had CTR, 18 stem cell transplantation, and 12 bone marrow transplant. Six patients had tumor recurrence but survived (mean, 9.3 +/- 8.3 years; range, 6 months-24 years). Recurrence was local (1), distant (2), and both (3) and was treated by resection, chemotherapy, and radiation. The mean age of survivors was 12.4 +/- 8.3 years (range, 2-34 years). In all stage IV cases, event-free survival was 30% and overall survival was 34%. Long-term complications occurred in 23 (44%) survivors, including endocrine disturbances (7), orthopedic (5), cataracts (2), adhesive bowel obstruction (2), hypertension (1), bronchiolitis (1), blindness (1), peripheral neuropathy (1), nonfunctioning kidney (1), cholelithiasis (1), and thyroid nodule (1). CONCLUSION: Only 34% of patients with stage IV NB survived despite aggressive multimodal therapy. Age of younger than 1 year, favorable pathology, CTR, and no recurrence were the only statistically significant factors that favored survival. Forty-four percent of survivors experienced late morbidity, and tumor recurred in 6 (11.5%) of 52. Patients should be monitored for tumor recurrence and long-term sequelae. New methods of treatment are required to achieve better outcomes.

Novel peptides secreted from human neuroblastoma: useful clinical tools?

BACKGROUND: Differentially expressed neuroblastoma (NB) proteins are vital for the development of new diagnostics and therapeutics. For example, secretory NB peptides (neuron-specific enolase and chromogranins) are clinically useful. We investigated polypeptide secretion by employing proteomic technologies to analyze proteins released from cultured NB cells. METHODS: Neuroblastoma cell lines (SK-N-AS, SK-N-DZ, and SK-N-FI) were grown in serum-free media. Conditioned media from each cell line was analyzed for secreted proteins by 2-dimensional polyacrylamide gel electrophoresis. Selected polypeptides were identified by liquid chromatography-linked tandem mass spectrometry. RESULTS: We identified 5 polypeptides that were secreted or shed by NB. Ubiquitin, beta2-microglobulin, insulin-like growth factor binding protein-2, superoxide dismutase (copper and zinc), and heat shock cognate 70-kd proteins were secreted from NB cells, as compared with control media. Elevated levels of these proteins have been described in serum/tissues under intracellular stress and malignancies, including NB. CONCLUSION: These novel secretory polypeptides may contribute to NB growth. The proteins may reveal additional tumor markers and permit putative use in the diagnosis and treatment of NB. Detection of these proteins in serum of children with NB vs controls (using 2-dimensional polyacrylamide gel electrophoresis and mass spectrometry techniques) is currently in progress.

Low Temperature Thermocouples: KP, "normal" silver, and copper versus Au-0.02 at% Fe and Au-0.07 at% Fe.

The Seebeck thermoelectric voltages of two dilute alloys of iron in gold, Au 0.02 at% Fe and Au-0.07 at% Fe, have been determined with respect to KP (a particular Ni-Cr alloy), "normal" silver, and copper in the temperature range from 4 to 280 K. The power series representation of these data, along with the calculated Seebeck coefficients and derivatives of the Seebeck coefficients, have been extrapolated to 0 K and are presented as a function of temperature. In addition to these reference data, seven different Au-0.07 at% Fe alloys were thermoelectrically intercompared in order to determine the variability in wires from different melts and from different manufacturers. The largest deviation found amounted to about 9 percent of the output of a KP versus Au-0.07 at% Fe thermocouple pair between 4 and 20 K. A more typical variation for this temperature range was 2 to 4 percent. Initial indications are that the reference data can be adjusted satisfactorily with data from spot calibrations on particular wires. The effect of heat treatment is illustrated by comparing our results to Rosenbaum's data for annealed and unannealed specimens of both Au-Fe alloys.

Thermal Conductivity Standard Reference Materials From 4 to 300 K. I. Armco Iron: Including Apparatus Description and Error Analysis.

An apparatus for the measurement of thermal conductivity, electrical resistivity, and thermopower of solids from 4 to 300 K is described. This apparatus, a modified version of the one used earlier in this laboratory, utilizes the steady-state, axial heat flow method. Included is a detailed discussion of the limitations of the apparatus, probable errors, and data analysis methods. Thermal conductivity, electrical resistivity, Lorenz ratio, and thermopower data are reported for several specimens of Armco iron for temperatures from 4 to 300 K. At low temperatures the electrical resistivity and thermal conductivity vary from specimen to specimen by more than 10 percent. However, the Lorenz ratios of these specimens differ by less than 2.5 percent; and the intrinsic resistivities calculated by using Matthiessen's rule differ by less than 0.5 percent of the total resistivities. Thus, Armco iron specimens can be used as standards by measuring the residual resistivities and utilizing the Lorenz ratio reported here.