Rapid Quantification of Ammonium Nitrate and Urea Nitrate Using Liquid Chromatography-High-Resolution Orbitrap Mass Spectrometry.

Resolution and sensitivity improvements in mass spectrometry technology have enabled renewed attempts at solving challenging analytical issues. One such issue involves the analysis of energetic ionic species. Energetic ionic species make up an important class of chemical materials, and a more robust and versatile analytical platform would provide tremendous value to the analytical community. Initial attempts at quantification of energetic ionic species employed high-resolution time-of-flight measurements with crown ether (CE) complexation and flow injection analysis (FIA). In this investigation, ammonium nitrate (AN) and urea nitrate (UN) in the presence of a crown ether complexation agent were explored by using high-resolution orbitrap mass spectrometry. Product ion scans of these signature complexes reveal positive identification of these energetic ionic species. Finally, quantification was demonstrated for both flow injection and liquid chromatography-mass spectrometry (LC-MS) analysis, suggesting the capability for routine and rapid analysis of these energetic ionic materials.

Technique of robotic esophagectomy.

Robotic surgery continues to grow in thoracic surgery, and currently plays an evolving role in esophagectomy. Robotic assisted minimally invasive esophagectomy (RAMIE) has continued to expand, with many institutions adapting the technique. As the overall experience continues to grow, new data is emerging in its support. We present our approach to this operation.

Patient reported outcomes (PROs) after minimally invasive and open esophagectomy.

Esophagectomy for esophageal malignancies remains an operation with significant potential morbidity and mortality. However, surgical outcomes continue to improve over time and focus has shifted toward not just good outcomes, but quality of life post operatively. Patient reported outcomes (PROs) focus of quality of life measures via validated patient surveys has increasingly become a significant focus. While PROs do have their limitations, they represent a glimpse into the symptomatology, quality of life, and well-being of a patient undergoing a procedure with inherent morbidity. Working to improve outcomes from the perspective of the patient is not a new concept, but has becoming increasingly relevant as surgical quality for all procedures improves. The optimal approach to esophagectomy is controversial. Minimally invasive approaches attempt to avoid laparotomy and thoracotomy with the thought of improving post-operative quality of life by mitigating complications related to those open surgical approaches. The data in favor of laparoscopy and thoracoscopy is quite strong and multiple randomized controlled trials exist in this realm supporting minimally invasive approaches with regards to quality of life outcomes and more rapid return to patient's preoperative baseline. The data in favor of a robotic approach for esophagectomy is not quite as robust, but more studies show that these approaches mirror the benefits of the laparoscopic and thoracoscopic approaches without robotic assistance.

Introduction to Clerkship: Bridging the Gap Between Preclinical and Clinical Medical Education.

BACKGROUND: Despite a diverse range of curricular advancements to address the difficult transition from classroom learning to clinical training during medical education, hurdles persist. A 4-week course was designed at the Philadelphia College of Osteopathic Medicine (PCOM) to make this transition easier. OBJECTIVES: To determine whether PCOM students' comfort and preparedness increased after taking a 4-week clinical transition course before third-year clinical clerkships, and to determine whether faculty perceptions of student preparedness and comfort were improved after participation in the course compared with previous third-year students. METHODS: Second-year osteopathic medical students at PCOM participated in a 4-week course, Introduction to Clinical Clerkship (I2C). The course included 16 small-group exercises, which all took place before students began their third-year clerkship rotations. The exercises in the course extended beyond the skills learned during their classroom years. Students were given a pre- and postcourse survey to evaluate their comfort level with 58 different aspects of clinical practice. Participating faculty were surveyed to evaluate their perception of student preparedness and comfort compared with previous third-year students who had not undergone the exercise. RESULTS: After completing the I2C course, third-year osteopathic medical students (n=232) reported increased comfort with 57 of the 58 learning objectives and each of the 5 coded clinical competency areas (patient assessment, effective communication, hospital logistics, procedural skills, and core knowledge) (P<.01). Preceptors reported that students who completed the I2C course were more prepared (54.5%) and more comfortable (63.4%) with clinical duties, as compared with their recollections of previous third-year osteopathic medical students. CONCLUSION: Within the 5 competencies, students on average felt more comfortable and were perceived by faculty as better prepared than previous students who had not taken the I2C course. The establishment of a preclinical transition exercise appears to help bridge the gap between the preclinical and clinical years. This learning model allows medical students to feel both more comfortable and better prepared throughout the transition from classroom learning to clinical rotations.

Polymorphic Phase Control of RDX-Based Explosives.

The polymorphic phase of 1,3,5-trinitro-1,3,5-triazine (RDX) was examined as a function of mass loading, solvent, and sample deposition technique. When RDX was deposited at a high mass loading, the vibrational modes in the obtained Raman spectra were indicative of concomitant polymorphism as both the α-RDX and ß-RDX phases were present. At low mass loadings, only ß-RDX was observed regardless of solvent when using the drop cast crystallization method. However, α-RDX (the thermodynamically stable polymorphic phase observed with visible quantities of the explosive) was observed when RDX deposits were dry transferred. Observation of α-RDX was independent of the initial mass loading or the initial deposition solvent when using the dry transfer methodology. These data indicate that the use of the dry transfer preparation method can be used to successfully prepare RDX-based test articles with the α-RDX phase regardless of the solvent used to initially dissolve the RDX, the initial deposition technique, or the mass loading.

Do simple beside lung function tests predict morbidity after rib fractures?

BACKGROUND: We evaluated if incentive spirometry volume (ISV) and peak expiratory flow rate (PEFR) could predict acute respiratory failure (ARF) in patients with rib fractures. METHODS: Normotensive, co-operative patients were enrolled prospectively. ISV and PEFR were measured on admission, at 24 h and at 48 h by taking the best of three readings each time. The primary outcome, ARF, was defined as requiring invasive or noninvasive positive pressure ventilation. RESULTS: 99 patients were enrolled (median age, 77 years). ARF occurred in 9%. Of the lung function tests, only a low median ISV at admission was associated with ARF (500 ml vs 1250 ml, p = 0.04). Three of 69 patients with ISV of ≥1000 ml versus six of 30 with ISV <1000 ml developed ARF (p = 0.01). Other significant factors were: number of rib fractures, tube thoracostomy, any lower-third rib fracture, flail segment. CONCLUSION: PEFR did not predict ARF. Admission ISV may have value in predicting ARF.

Classification of smokeless powders using laser electrospray mass spectrometry and offline multivariate statistical analysis.

A direct, sensitive, and rapid method for the detection of smokeless powder components, from five different types of ammunition, is demonstrated using laser electrospray mass spectrometry (LEMS). Common components found in powder, such as ethyl centralite, methyl centralite, dibutyl phthalate, and dimethyl phthalate, are detected under atmospheric conditions without additional sample preparation. LEMS analysis of the powders revealed several new mass spectral features that have not been identified previously. Offline principal component analysis and discrimination of the LEMS mass spectral measurements resulted in perfect classification of the smokeless powder with respect to manufacturer.

Differentiation of eight phenotypes and discovery of potential biomarkers for a single plant organ class using laser electrospray mass spectrometry and multivariate statistical analysis.

Laser electrospray mass spectrometry (LEMS) coupled with offline multivariate statistical analysis is used to discriminate eight phenotypes from a single plant organ class and to find potential biomarkers. Direct analysis of the molecules from the flower petal is enabled by interfacing intense (10(13) W/cm(2)), nonresonant, femtosecond laser vaporization at ambient pressure with electrospray ionization for postionization of the vaporized analytes. The observed mass spectral signatures allowed for the discrimination of various phenotypes using principal component analysis (PCA) and either linear discriminant analysis (LDA) or K-nearest neighbor (KNN) classifiers. Cross-validation was performed using multiple training sets to evaluate the predictive ability of the classifiers, which showed 93.7% and 96.8% overall accuracies for the LDA and KNN classifiers, respectively. Linear combinations of significant mass spectral features were extracted from the PCA loading plots, demonstrating the capability to discover potential biomarkers from the direct analysis of tissue samples.

Determination of inorganic improvised explosive device signatures using laser electrospray mass spectrometry detection with offline classification.

The mass spectral detection of low vapor pressure, inorganic-based explosive signatures including ammonium nitrate, chlorate, perchlorate, sugar, and the constituents contained within black powder are reported using laser electrospray mass spectrometry. The ambient pressure mass spectrometry technique combining nonresonant, femtosecond laser vaporization with electrospray postionization revealed primary and secondary signatures for trace quantities of inorganic explosives. A mixture of complexation agents in the electrospray solvent enabled the simultaneous detection of vaporized cations, anions, and neutrals in a single measurement. An offline classifier discriminated the inorganic-based explosives based on the mass spectral signatures resulting in high fidelity identification.

Nonresonant femtosecond laser vaporization of aqueous protein preserves folded structure.

Femtosecond laser vaporization-based mass spectrometry can be used to measure protein conformation in vitro at atmospheric pressure. Cytochrome c and lysozyme are vaporized from the condensed phase into the gas phase intact when exposed to an intense (10(13) W/cm(2)), nonresonant (800 nm), ultrafast (75 fs) laser pulse. Electrospray postionization time-of-flight mass spectrometry reveals that the vaporized protein maintains the solution-phase conformation through measurement of the charge-state distribution and the collision-induced dissociation channels.

Analysis of amphiphilic lipids and hydrophobic proteins using nonresonant femtosecond laser vaporization with electrospray post-ionization.

Amphiphilic lipids and hydrophobic proteins are vaporized at atmospheric pressure using nonresonant 70 femtosecond (fs) laser pulses followed by electrospray post-ionization prior to being transferred into a time-of-flight mass spectrometer for mass analysis. Measurements of molecules on metal and transparent dielectric surfaces indicate that vaporization occurs through a nonthermal mechanism. The molecules analyzed include the lipids 1-monooleoyl-rac-glycerol, 1,2-dihexanoyl-sn-glycero-3-phosphocholine, 1,2-dimyristoyl-sn-glycero-3-phosphocholine, and the hydrophobic proteins gramicidin A, B, and C. Vaporization of lipids from blood and milk are also presented to demonstrate that lipids in complex systems can be transferred intact into the gas phase for mass analysis.

Nonresonant femtosecond laser vaporization with electrospray postionization for ex vivo plant tissue typing using compressive linear classification.

Laser electrospray mass spectrometry (LEMS) with offline classification is used to discriminate plant tissues at atmospheric pressure using an intense (10(13) W cm(-2)), nonresonant (800 nm) femtosecond laser pulse to vaporize cellular content for subsequent mass analysis. The tissue content of the plant within the 0.05 mm(2) laser interaction region is vaporized into the electrospray plume where the molecules are ionized prior to transfer into the mass spectrometer. The measurements for a flower petal, leaf, and stem of an impatiens plant reveal mass spectral signatures that enable discrimination as performed using a compressive linear classifier. The statistical analysis of the plant tissue samples reveals reproducibility of the data for replicate tissue samples and within a single tissue sample. A similar degree of discrimination was achieved for the green and white regions of aphelandra squarrosa (zebra plant) leaves.

Mass analysis of biological macromolecules at atmospheric pressure using nonresonant femtosecond laser vaporization and electrospray ionization.

A nonresonant femtosecond laser pulse, with an intensity of 10(13) Wcm(-2), vaporizes proteins and biomolecules intact, regardless of molecular structure, size or electronic structure for subsequent electrospray ionization and transfer into a mass spectrometer. Rapid, direct analysis from dried sample, aqueous solution and cellular material is demonstrated at atmospheric pressure using laser electrospray mass spectrometry (LEMS). Measurements are presented for lysozyme (14.3 kDa), hemoglobin from human blood, ovalbumin (45 kDa) from hen egg white and phospholipids from hen egg yolk. Mass analysis of biological material is performed without dilution, extraction or sample preparation, other than placing the biological material onto the sample plate.

Predictors of returning to oral feedings after feeding tube placement for patients poststroke during inpatient rehabilitation.

OBJECTIVES: To identify the frequency and characteristics of patients admitted to inpatient rehabilitation (IPR) following a stroke who are able return to oral feedings and have their feeding tube (FT) removed prior to discharge from IPR, the timing of FT removal, and implications for outcomes. METHODS: Medical records were identified by admission rehabilitation impairment code (RIC) for stroke (RIC 01), and reviews were completed by two physiatrists and two speech language pathologists. At random, 25% of the charts were reviewed by a second rater for data quality control. Measures collected during the chart review included the following: age, gender, onset of stroke, rehabilitation length of stay (LOS), admission and discharge FIM, discharge destination, diet level, and feeding tube status. RESULTS: One hundred forty-three patients were identified as subjects for this investigation who had an FT and were NPO upon IPR admission. Overall, 46.9% (67/143) of the patients returned to three meals daily prior to discharge from IPR. The mean days post stroke onset until returning to three meals daily was 38.43 days (SD=26.36). Twenty percent (30/143) of the patients were able to have their FT tube removed prior to discharge from IPR. Factors associated with returning to three meals included gender (ie, female), longer IPR LOS, and higher admission FIM scores at IPR. Factors associated with removal of the feeding tube included a longer IPR LOS and younger age. Patients who were able to have their FT removed were more likely to be discharged to home. CONCLUSION: Individuals with longer IPR LOS were more likely to return to three meals daily and have their feeding tubes removed prior to discharge.

Identification of explosives and explosive formulations using laser electrospray mass spectrometry.

Mass analysis is demonstrated for the detection of sub-microgram quantities of explosive samples on a metallic surface at atmospheric pressure using laser electrospray mass spectrometry (LEMS). A non-resonant femtosecond duration laser pulse vaporizes native samples for subsequent electrospray ionization and transfer into a time-of-flight mass spectrometer. LEMS was used to detect 2,3-dimethyl-2,3-dinitrobutane (DMNB), 1,3,5-trinitroperhydro-1,3,5-triazine (RDX), 3,4,8,9,12,13-hexaoxa-1,6-diazabicyclo[4.4.4]tetradecane (HMTD), and 3,3,6,6,9,9-hexamethyl-1,2,4,5,7,8-hexaoxacyclononane (TATP) deposited on a steel surface. LEMS was also used to directly analyze composite propellant materials containing an explosive to determine the molecular composition of the explosive pellets at atmospheric pressure.

Analysis of pharmaceutical compounds from glass, fabric, steel, and wood surfaces at atmospheric pressure using spatially resolved, nonresonant femtosecond laser vaporization electrospray mass spectrometry.

Laser electrospray mass spectrometry (LEMS) is demonstrated for pharmaceutical samples at atmospheric pressure. A nonresonant, femtosecond duration laser pulse vaporizes native samples at atmospheric pressure into an electrospray plume for ionization with subsequent transfer into a time-of-flight mass spectrometer. The active ingredients in pharmaceutical tablets were detected in the presence of binders and fillers in intact formulations using LEMS. Mass spectra were also obtained for microgram amounts of the pharmaceutical compounds loratadine, oxycodone, and atenolol deposited on glass, wood, steel, and polyester fabric. The neutral capture efficiency by the electrospray plume for nonresonant laser vaporization of oxycodone and atenolol desorbed from steel is 2.4% +/- 1.5% and 0.25% +/- 0.18%, respectively. LEMS imaging of the spatial distribution of an oxycodone spot on a metal slide with resolution of 250 mum is also presented.

Mass spectrometry of intact neutral macromolecules using intense non-resonant femtosecond laser vaporization with electrospray post-ionization.

Intact, nonvolatile, biological macromolecules can be transferred directly from the solid state into the gas phase, in ambient air, for subsequent mass spectral analysis using non-resonant femtosecond (fs) laser desorption combined with electrospray ionization (ESI). Mass spectral measurements for neat samples, including a dipeptide, protoporphyrin IX and vitamin B12 adsorbed on a glass insulating surface, were obtained using an 800 nm, 70 fs laser with an intensity of 10(13) W cm(-2). No appreciable signal was detected when atmospheric matrix-assisted or neat (matrix-free) fs laser desorption was performed without ESI, indicating neutral desorption.

Adaptive reshaping of objects in (multiparameter) Hilbert space for enhanced detection and classification: an application of receiver operating curve statistics to laser-based mass spectroscopy.

We propose a new approach to the classical detection problem of discrimination of a true signal of interest from an interferent signal, which may be applied to the area of chemical sensing. We show that the detection performance, as quantified by the receiver operating curve (ROC), can be substantially improved when the signal is represented by a multicomponent data set that is actively manipulated by means of a shaped laser probe pulse. In this case, the signal sought (agent) and the interfering signal (interferent) are visualized by vectors in a multidimensional detection space. Separation of these vectors can be achieved by adaptive modification of a probing laser pulse to actively manipulate the Hamiltonian of the agent and interferent. We demonstrate one implementation of the concept of adaptive rotation of signal vectors to chemical agent detection by means of strong-field time-of-flight mass spectrometry.