C5 C7 Research Articles

Hydrocarbon evaporative loss from shale core samples as revealed by Rock-Eval and thermal desorption-gas chromatography analysis: Its geochemical and geological implications

The S1 peak generated by Rock-Eval analysis of source rock and reservoir interval core and cuttings samples has been routinely employed for in-place hydrocarbon resources assessment by petroleum geochemists, geologists and even engineers. Significant evaporative loss of gaseous and light hydrocarbons (up to C10) can occur during core and cuttings collection and storage, and subsequent sample preparation in the laboratory before instrumental analysis. Consequently a correction to the S1 values is needed in order to obtain a more accurate estimate of the resources. To investigate the effect of evaporative loss on both the amount and the composition of the hydrocarbons retained in shale, a time-series of Rock-Eval and thermal desorption-gas chromatography (TD-GC) analyses have been carried out on an organic-rich Devonian Duvernay Formation shale core sample from the Western Canada Sedimentary Basin (WCSB) and an organic-lean Ordovician Lotbinière Formation shale core sample from Quebec, Canada. The results suggest that the content of total organic carbon (TOC) may play an important role in retaining and preserving light hydrocarbons in sedimentary rocks. A total loss of gaseous and light liquid hydrocarbons up to C9 is shown to take place within 21 h of sample preparation for the low TOC (<1%) Ordovician Lotbinière shale when the powdered sample was left exposed to the open air, accounting for a 38% decrease in its Rock-Eval S1 peak. The Rock-Eval S1 peak can be reduced by 29% even if the powdered sample has been stored in a sealed container for just over a week. In contrast, the volatile loss has been found to occur at a much slower rate for the high TOC (>11%) Devonian Duvernay shale core sample. After 360 h of exposure to the open air, the powdered Duvernay shale sample shows only 15% decline in its Rock-Eval S1 peak, and still contains high relative concentrations of C7–C9 hydrocarbons. In addition, the evaporative loss of some isomers of C5–C7 hydrocarbons from the organic-rich shale is not fully in agreement with their GC retention/elution behavior, but appears to be partially controlled by their adsorption/desorption on the organic matter and mineral matrix. This suggests that the C5–C8 gasoline range hydrocarbon parameters should be used with caution for oil–oil correlation for unconventional shale and tight petroleum systems. While the findings in this study validate the current industrial practice that targets organic-rich and mature shale intervals for unconventional shale gas and oil exploration because of their large hydrocarbon storage capacity, the results also have an important implication that high TOC content may adversely affect the production efficiency of shale and tight hydrocarbon reservoirs due to the strong adsorption of hydrocarbons by the high maturity organic matter.

Perfluoroalkyl substances (PFAS) in river and ground/drinking water of the Ganges River basin: Emissions and implications for human exposure

Many perfluoroalkyl substances (PFAS) are ubiquitous environmental contaminants. They have been widely used in production processes and daily-use products or may result from degradation of precursor compounds in products or the environment. India, with its developing industrialization and population moving from traditional to contemporary lifestyles, represents an interesting case study to investigate PFAS emission and exposure along steep environmental and socioeconomic gradients. This study assesses PFAS concentrations in river and groundwater (used in this region as drinking water) from several locations along the Ganges River and estimates direct emissions, specifically for PFOS and PFOA. 15 PFAS were frequently detected in the river with the highest concentrations observed for PFHxA (0.4–4.7 ng L−1) and PFBS (<MQL – 10.2 ng L−1) among PFCAs and PFSAs, respectively. Prevalence of short-chain PFAS indicates that the effects of PFOA and PFOS substitution are visible in environmental samples from India. The spatial pattern of C5–C7 PFCAs co-varied with that of PFOS suggesting similar emission drivers. PFDA and PFNA had much lower concentrations and covaried with PFOA especially in two hotspots downstream of Kanpur and Patna. PFOS and PFOA emissions to the river varied dramatically along the transect (0.20–190 and 0.03–150 g d−1, respectively). PFOS emission pattern could be explained by the number of urban residents in the subcatchment (rather than total population). Per-capita emissions were lower than in many developed countries. In groundwater, PFBA (<MQL – 9.2 ng L−1) and PFBS (<MQL – 4.9 ng L−1) had the highest concentrations among PFCAs and PFSAs, respectively. Concentrations and trends in groundwater were generally similar to those observed in surface water suggesting the aquifer was contaminated by wastewater receiving river water. Daily PFAS exposure intakes through drinking water were below safety thresholds for oral non-cancer risk in all age groups.

The cervical anatomy of Samotherium , an intermediate-necked giraffid

Giraffidae are represented by many extinct species. The only two extant taxa possess diametrically contrasting cervical morphology, as the okapi is short-necked and the giraffe is exceptionally long-necked. Samotherium major, known from the Late Miocene of Samos in Greece and other Eurasian localities, is a key extinct giraffid; it possesses cervical vertebrae that are intermediate in the evolutionary elongation of the neck. We describe detailed anatomical features of the cervicals of S. major, and compare these characteristics with the vertebrae of the two extant giraffid taxa. Based on qualitative morphological characters and a quantitative analysis of cervical dimensions, we find that the S. major neck is intermediate between that of the okapi and the giraffe. Specifically, the more cranial (C2–C3) vertebrae of S. major represent a mosaic of features shared either with the giraffe or with the okapi. The more caudal (C5–C7) S. major vertebrae, however, appear transitional between the two extant taxa, and hence are more unique. Notably, the C6 of S. major exhibits a partially excavated ventral lamina that is strong cranially but completely absent on the caudal half of the ventral vertebral body, features between those seen in the giraffe and the okapi. Comprehensive anatomical descriptions and measurements of the almost-complete cervical column reveal that S. major is a truly intermediate-necked giraffid. Reconstructions of the neck display our findings.

Control of ozonolysis kinetics and aerosol yield by nuances in the molecular structure of volatile organic compounds

Abstract Secondary organic aerosol (SOA) plays integral roles in climate and human health, yet there remains a limited understanding of the mechanisms that lead to its formation and ultimate fate, as evidenced by a disparity between modeled atmospheric SOA loadings and field measurements. This disparity highlights the need for a more accurate representation of the molecular-level interactions between SOA sources and oxidative pathways. Due to the paucity of detailed chemical data for most SOA precursors of atmospheric relevance, models generally predict SOA loadings using structure activity relationships generalized to classes of SOA precursors. However, the kinetics and SOA forming potential of molecules are nuanced by seemingly minor structural differences in parent molecules that may be neglected in models. Laboratory chamber studies were used to measure SOA yields and rate constants for the ozonolysis of several linear, cyclic and oxygenated C5–C7 alkenes whose molecular structure vary in the site of unsaturation and/or the presence/position of functional groups and that represent atmospherically relevant classes of molecules. For the alkenes studied in this work, we found greater SOA yields for cyclic compounds compared to their linear analogs. For 1-alkenes, SOA yield increased with carbon number but was also dependent on the position of the double bond (internal vs terminal). Both the identity and position of oxygenated functional groups influenced SOA yield and kinetics through steric and electronic effects. Additionally, terminal alkenes generally resulted in a greater SOA yield than analogous internal alkenes, indicating that the position of the double bond in alkenes plays an important role in its atmospheric fate. Herein, we demonstrate the nuanced behavior of these ozonolysis reactions and discuss relationships between parent compound molecular structure and SOA yield and kinetics.

Laboratory photochemical processing of aqueous aerosols: formation and degradation of dicarboxylic acids, oxocarboxylic acids and α-dicarbonyls

Abstract. To better understand the photochemical processing of dicarboxylic acids and related polar compounds, we conducted batch UV irradiation experiments on two types of aerosol samples collected from India, which represent anthropogenic (AA) and biogenic (BA) aerosols, for time periods of 0.5 to 120 h. The irradiated samples were analyzed for molecular compositions of diacids, oxoacids and α-dicarbonyls. The results show that photochemical degradation of oxalic (C2), malonic (C3) and other C8–C12 diacids overwhelmed their production in aqueous aerosols, whereas succinic acid (C4) and C5–C7 diacids showed a significant increase (ca. 10 times) during the course of irradiation experiments. The photochemical formation of oxoacids and α-dicarbonyls overwhelmed their degradation during the early stages of experiment except for ω-oxooctanoic acid (ωC8), which showed a similar pattern to that of C4. We also found a gradual decrease in the relative abundance of C2 to total diacids and an increase in the relative abundance of C4 during prolonged experiment. Based on the changes in concentrations and mass ratios of selected species with the irradiation time, we hypothesize that iron-catalyzed photolysis of C2 and C3 diacids controls their concentrations in Fe-rich atmospheric waters, whereas photochemical formation of C4 diacid (via ωC8) is enhanced with photochemical processing of aqueous aerosols in the atmosphere. This study demonstrates that the ambient aerosols contain abundant precursors that produce diacids, oxoacids and α-dicarbonyls, although some species such as oxalic acid decompose extensively during an early stage of photochemical processing.

Guayule (Parthenium argentatum) pyrolysis biorefining: Production of hydrocarbon compatible bio-oils from guayule bagasse via tail-gas reactive pyrolysis

Abstract Guayule (Parthenium argentatum) is a woody desert shrub cultivated in the southwestern United States as a source of natural rubber, organic resins, and high energy biofuel feedstock from crop residues. We used guayule bagasse, the residual biomass after latex extraction as feedstock in a pyrolysis process that employs a reactive gas environment to formulate a special intermediate bio-oil product that allows use of conventional hydrotreating with conventional noble metal catalysts and a simple distillation process to synthesize hydrocarbon (drop-in) fuels. The said guayule-bagasse tail gas reactive pyrolysis (TGRP) process comprises pyrolyzing the guayule bagasse in a fluidized-bed reactor in the presence of a reactive and flammable tail gas (comprising CO ∼ 30%, CH4 ∼ 16%, CO2 ∼ 40%, H2 ∼ 10%, C2H4 ∼ traces) generated in the pyrolysis process and without the use of catalyst to produce bio-oil with C/O molar ratio of 14/1 in organic yields of 34–40 wt% having an energy content of 31–37.5 MJ/kg. When we further processed the said bio-oil by centrifugation, we obtained 85 wt% yield and further 50–65 wt% yields following a continuous hydrotreatment over common noble metals (Pt, Ru or Pd) on a carbon support. Distillation of this mixture yielded >95 wt% hydrocarbon liquid fuel mixture comprising 30.4% gasoline (C5–C7), 37% jet (C8–C12) and 24% diesel (C13–C22). Analysis of a composite mixture of the hydrotreated product from the bagasse showed the majority of the sample (66%) was C12 and below, which falls within the gasoline (naphtha) range with the greatest fraction of naphtha falling within the C8–C10 range. Beyond C12, the molecular weights increased through the diesel range (34%), with C37 being the highest observable molecular weight. The product met several ASTM standards for drop-in fuels, but the sulfur content (primarily due to latex extraction additives) was relatively high at around 300 ppm, indicating that hydrodesulfurization may be required to be infrastructure ready.

Transvenous vagus nerve stimulation does not modulate the innate immune response during experimental human endotoxemia: a randomized controlled study.

IntroductionVagus nerve stimulation (VNS) exerts beneficial anti-inflammatory effects in various animal models of inflammation, including collagen-induced arthritis, and is implicated in representing a novel therapy for rheumatoid arthritis. However, evidence of anti-inflammatory effects of VNS in humans is very scarce. Transvenous VNS (tVNS) is a newly developed and less invasive method to stimulate the vagus nerve. In the present study, we determined whether tVNS is a feasible and safe procedure and investigated its putative anti-inflammatory effects during experimental human endotoxemia.MethodsWe performed a randomized double-blind sham-controlled study in healthy male volunteers. A stimulation catheter was inserted in the left internal jugular vein at spinal level C5–C7, adjacent to the vagus nerve. In the tVNS group (n = 10), stimulation was continuously performed for 30 minutes (0–10 V, 1 ms, 20 Hz), starting 10 minutes before intravenous administration of 2 ng kg−1Escherichia coli lipopolysaccharide (LPS). Sham-instrumented subjects (n = 10) received no electrical stimulation.ResultsNo serious adverse events occurred throughout the study. In the tVNS group, stimulation of the vagus nerve was achieved as indicated by laryngeal vibration. Endotoxemia resulted in fever, flu-like symptoms, and hemodynamic changes that were unaffected by tVNS. Furthermore, plasma levels of inflammatory cytokines increased sharply during endotoxemia, but responses were similar between groups. Finally, cytokine production by leukocytes stimulated with LPS ex vivo, as well as neutrophil phagocytosis capacity, were not influenced by tVNS.ConclusionstVNS is feasible and safe, but does not modulate the innate immune response in humans in vivo during experimental human endotoxemia.Trial registrationClinicaltrials.gov NCT01944228. Registered 12 September 2013.

RuO4 catalyzed dihydroxylation for the synthesis of mixed medium-chain triacylglycerols

RuO4 catalyzed dihydroxylation of allyl acylates (C5 to C12) to glyceryl acylates is reported. The dihydroxylation was a major product (61–85%) with C5–C7 whereas carbonyl compounds by double bond fission were major with C8–C12 systems. 1-Hexanoylglycerol, obtained in high yields (85%), was further acylated with medium chain fatty acid chlorides to prepare mixed medium chain triglycerides (85–90%). Hence, a facile preparation of triacylglycerols such as C6–C6–C6, C6–C8–C8, C6–C10–C10, and C6–C12–C12 is accomplished.

Continuous-Flow Hydroisomerization of C5–C7 Alkanes Using Mechanochemically Synthesized Supported Pt and Pd-SBA-15 Materials

SBA-15 materials exhibit important properties including large surface area, highly ordered mesopores, and high stability in a variety of catalytic reactions. In this study, Al and Zr-loaded SBA-15 materials (Si/Zr = 30, Si/Al = 30), 50 molar ratio with Pd (1, 2, and 4% (w/w)) and Pt (0.5 and 1% (w/w)) were tested in the isomerization of C5–C7 linear alkanes. These solids were characterized using thermal gravimetric analysis–differential thermal analysis (TGA–DTA), nitrogen physisorption, and energy dispersive X-ray (EDX). Interestingly, the low porosity SBA-15 materials loaded with 2% (w/w) Pd were most active catalysts for n-heptane isomerization. The mechanochemical addition of tungsten also resulted in the increase of catalytic activity for the reaction. The results herein demonstrate the possibilities of SBA-15 catalysts as a commercial catalyst alternative in the catalytic isomerization of hydrocarbons.

Fatal Vertebral Artery Injury in Penetrating Cervical Spine Trauma.

Study Design. This case illustrates complications to a vertebral artery injury (VAI) resulting from penetrating cervical spine trauma. Objectives. To discuss the management of both VAI and cervical spine trauma after penetrating gunshot wound to the neck. Summary of Background Data. Vertebral artery injury following cervical spine trauma is infrequent, and a unilateral VAI often occurs without neurologic sequela. Nevertheless, devastating complications of stroke and death do occur. Methods. A gunshot wound to the neck resulted in a C6 vertebral body fracture and C5–C7 transverse foramina fractures. Neck CT angiogram identified a left vertebral artery occlusion. A cerebral angiography confirmed occlusion of the left extracranial vertebral artery and patency of the remaining cerebrovascular system. Following anterior cervical corpectomy and stabilization, brainstem infarction occurred and resulted in death. Results. A fatal outcome resulted from vertebral artery thrombus propagation with occlusion of the basilar artery triggering basilar ischemia and subsequent brainstem and cerebellar infarction. Conclusions. Vertebral artery injury secondary to cervical spine trauma can lead to potentially devastating neurologic sequela. Early surgical stabilization, along with anticoagulation therapy, contributes towards managing the combination of injuries. Unfortunately, despite efforts, a poor outcome is sometimes inevitable when cervical spine trauma is coupled with a VAI.

Gas phase adsorption of alkanes, alkenes and aromatics on the sulfone-DUT-5 Metal Organic Framework

A sulfone functionalized DUT-5 Metal Organic Framework ‘SO2-DUT-5’ was synthesized using 4,4′-bibenzoic acid-2,2′-sulfone linkers. Its adsorption properties were studied and compared to those of the pristine DUT-5 material. The inverse gas chromatographic method was used to study the adsorption of C5–C7 linear, branched and cyclic alkanes, alkenes and aromatic molecules. SO2-DUT-5 shows shape-selective behaviour in the adsorption of linear, branched and iso-alkanes, whereas DUT-5 is non-selective. The presence of sulfone groups results in both a reduced pore size and more specific interaction sites, leading to the shape-selective behaviour towards linear alkanes and the slightly elevated preference for aromatic compounds in the low coverage area.The separation of n-hexane/benzene and 1-hexene/benzene mixtures at higher coverage was studied by performing breakthrough experiments at different temperatures and pressures. A remarkable change in selectivity is observed when the loading of the adsorbing molecules increases. At low degree of pore filling, no significant separation between n-hexane/benzene or 1-hexene/benzene occurs, while at higher loading separation becomes apparent with a preferential adsorption of benzene. This separation at high loading is a result of the more favourable packing of benzene in this unidimensional pore system.

Determination of naphtha composition by near infrared spectroscopy and multivariate regression to control steam cracker processes

Naphtha is an important feedstock for the petrochemical industry and accurate measurement of its detailed composition is essential for the optimization of pyrolysis processes. In the present work, the suitability of using near infrared (NIR) for the determination of 38 parameters used to characterize naphtha was evaluated: pooled composition (PIONA); specific composition groups (C3 paraffins; C4–C12 n-paraffins; C4–C12 iso-paraffins; C5–C7+ naphthenics; C8–C10 aromatics; C4–C6 olefins) and individual components (toluene, benzene, iso-pentane, cyclopentane, methyl cyclopentane; cyclohexane, xylenes, 1,3 butadiene and isoprene). Besides the usual comparison against reference methods, NIR predictions were also evaluated for their ultimate use in determining the coil outlet temperature (COT) for process control. 28 models for the naphtha parameters presented root mean square error (RMSEP) values lower or close to the reproducibility of the reference method and exhibited satisfactory correlation values (r2) when compared with r2max. Among the ten remaining parameters, two (1,3 butadiene and isoprene) presented very low concentrations and it was not possible to obtain a suitable model. Eight parameters had RMSEP values higher than the intralaboratory reproducibility and/or r2 values lower than expected. Despite this, the complete naphtha composition obtained from NIR prediction was demonstrated to be quite suitable for COT simulation, providing accurate COT values compared to the values estimated from the reference method.

Primary epidural liposarcoma of the cervical spine: Technical case report and review of the literature

Abstract Liposarcoma is the most common soft tissue sarcoma in adults. These tumors have a high incidence of osseous metastases, with a propensity to the spine; however, primary spinal involvement is very rare. A 56-year-old female patient presented with a 4 month history of cervical pain, including radiation to both upper limbs, without radicular distribution. Magnetic resonance imaging (MRI) showed an epidural lesion with gadolinium enhancement and bilateral extension into the intervertebral neural foramina (C5–C7), with spreading on the right side of the tumor into paravertebral tissue. The histopathological diagnosis was myxoid liposarcoma. To our knowledge it is the first case of primary myxoid liposarcoma of the cervical spine in the literature. Although rare, our case demonstrates that liposarcoma should be considered in the differential diagnosis of cervical tumors.

Morphological distinction of cervical nerve roots associated with motor function in 219 healthy volunteers: a multicenter prospective study.

A prospective study. To examine the diameter (mm), transverse diameter (mm), and cross-sectional area (mm²) of the C5, C6, and C7 nerve roots using ultrasonography. Each of the cervical nerve roots affected a different motor or sensory area. Although there were several studies that performed a detailed assessment of cervical nerve root anatomy in cadavers, only a few studies on the thickness of cervical nerve roots in living specimens have been performed. We examined whether the thickness of the C5, C6, and C7 nerve roots, as well as the area supplied by each of the roots, varied. All 219 subjects (99 males and 120 females; mean age, 47 ± 15 yr) were healthy volunteers. The diameter and the transverse diameter were measured via ultrasonography, and the cross-sectional area was calculated for each of the C5-C7 nerve roots. The following diameter measurements (right and left, respectively) were obtained: C5, 2.8 and 2.9 mm; C6, 3.6 and 3.8 mm; and C7, 3.3 and 3.4 mm. The following transverse diameter measurements were obtained (right and left, respectively): C5, 2.8 and 3.0 mm; C6, 3.7 and 3.8 mm; and C7, 3.5 and 3.4 mm. The following cross-sectional area measurements (right and left, respectively) were obtained: C5, 6.3 and 6.4 mm²; C6, 10.7 and 11.0 mm²; and C7, 8.8 and 8.8 mm². Based on the 3 measurement methods, the C5 nerve root was significantly thinner than the other 2 nerve roots (P < 0.001), and the C7 nerve root was smaller than the C6 nerve root (P = 0.001). The C5 nerve root was significantly thinner than the C6 and C7 cervical nerve roots. The fact that the C5 nerve is thinner may render it more susceptible to damage during cervical surgery.

Isomerization of C5–C7 paraffins over a Pt/WO3–ZrO2 catalyst using industrial feedstock

Much research has been published on the isomerization of C5–C7 paraffins using Pt/WO3–ZrO2 (PtWZr) catalysts. However, to our knowledge, most of these researchers only used model feedstocks. Therefore, we tested the activity of a Pt/WO3–ZrO2 catalyst using real raw materials (a mixture of n-hexane + i-hexanes or an industrial feedstock) for the industrial production of high-quality gasoline. A reliable method was developed to study the activity of a PtWZr sample with w(WO3) = 12 % and w(Pt) = 0.25 %. The catalyst was tested in a continuous flow reactor connected to a gas chromatograph and two sample collectors. Tests were carried out under different conditions to optimize the reaction at 250 and 300 °C. The results were analyzed to determine the product composition and to calculate the final equivalent research octane number. While a high conversion rate was achieved using the model reactant, the yield decreased significantly when more real raw materials were used. Therefore, our results suggest that real feedstock should be used to determine whether a catalyst has sufficient activity for the isomerization of C5–C7 paraffins in industrial applications.

Quantification of Pediatric and Adult Cervical Vertebra—Anatomical Characteristics by Age and Gender for Automotive Application

Objective: The cervical anatomy has been shown to affect injury patterns in vehicle crashes. Characterizing the spine anatomy and changes associated with growth and gender is important when assessing occupant protection. In this study, selected cervical characteristics were quantified.Methods: Computed tomography (CT) scans of 750 patients were selected from the University of Michigan trauma database; 314 were children and 436 were adults. Four variables were obtained: the maximum spinal canal radius, vertebral body depth, facet angles, and retroversion angles.Results: The cervical spine measurements varied with age and gender. The body depth increased nonlinearly with age. The average vertebral body depth at C4 was 9.2 ± 0.38 mm in the 0–3 age group, 15.7 ± 0.29 mm in the 18–29 age group, and 17.2 ± 0.46 mm in the 60+ age group. Pediatric and adult males had larger vertebral body depth than females overall, irrespective of vertebral level (P <.001). Compared to females, the vertebral body depth was 8–9 percent greater in male children and 13–16 percent greater in adult males. The average radius varied with gender, with male children generally having a larger radius than females irrespective of vertebral level (P <.001). Overall, spinal canal radius was smallest in the 0–3 and 60+ age groups and largest in the 18–29 age group. The C4 radius was 5.91 ± 0.17, 6.28 ± 0.14, and 6.73 ± 0.17 mm respectively. The radius was larger in the 4–7 age group than in the 0–3 age group, irrespective of vertebral level (P <.0001). There were nonsignificant radius changes between the 4–7 and 8–11 age groups and the 8–11 and age 12–17 groups, suggesting that the size of the spinal cord reaches near maturation by the age of 7.Facet angles decreased with age in children and increased with age in adults. The average facet angles were largest in the 0–3 age group (P <.1, C2–C6). Adult facet angles were greater in the 60+ age group than in the 18–29 age group (P <.0001, C2–C6). Males had larger facet angles than females overall (P <.01 at C2, C5–C7). The retroversion angles were largest at C6 and C7. They increased with age in children and decreased in the adult population; they were larger (5–22%) in the 18–29 age group than in the 60+ age group (P <.0001, C2–C6).Conclusions: The results obtained in this study help explain variations in cervical anatomical changes associated with age and gender. The information is useful when assessing differences in injury patterns between different segments of the population. Anatomical measurements of the cervical spine should be considered for the development of models used to assess injury mechanisms for various occupant age groups.

54. Cutaneous silent period in brachial plexus injury

Objectives The cutaneous silent period (CSP) is a spinal inhibitory reflex mediated primarily by small-diameter A-delta fibers, which enter the spinal dorsal horn and suppress activity in spinal motor nuclei in neighboring myotomes. The aim of the study was to define if CSP testing may be particularly useful in evaluation of brachial plexus injury, especially contributing to diagnosis of root avulsion. Methods In 11 patients with traumatic brachial plexus injury (8 males, age 18–62 years) we performed clinical examination, myelo CT and neurophysiological testing. Needle EMG was obtained from the main root muscles of C5–C8 myotomes. CSP was recorded by painful stimuli while the subject maintains a moderately strong voluntary muscle contraction and impulses were delivered to thumb (C6 dermatome), middle (C7) and little (C8) fingers. Results Clinical and EMG examination proved motor root damage of C5 in 3 subjects, C5 and C6 in 3 subjects, C5–C7 in 3 subjects, C5–C8 in 2 subjects. The CSP was partially absent in 3 subjects, however, well preserved in 8 subjects. Conclusion in theory, CSP can be used to quickly monitor afferent impulses travelling through damaged cervical roots, however, in brachial plexus avulsion CSP abnormalities were found only in a few cases. CSP is a robust protective plurisegmental spinal reflex, which is maintained even with a preservation of minimal functional afferent fibers and/or because the afferent signal is amplified within the spinal cord. Supported by Research Projects of Charles University PRVOUK P34, Grant Project of Czech Ministry of Health NT12282, NT13693.

Different Patterns of Nerve Enlargement in Polyneuropathy Subtypes as Detected by Ultrasonography

The purpose of our study was to examine how the pathologic type of polyneuropathy affects nerve size as assessed by high-resolution ultrasonography with a 15 MHz transducer. Cross-sectional area (CSA) of the C5–C7 nerve roots and several upper and lower limb nerves at multiple sites was measured in 38 patients with acquired diffuse sensorimotor demyelinating or axonal polyneuropathy and in 34 healthy control subjects. Significant differences were found among the groups for all nerve and root segments: Both types of polyneuropathy are characterized by nerve enlargement in comparison to controls, but in different patterns. In demyelinating polyneuropathies, an additional degree of nerve thickening appears in proximal upper limb nerves and cervical nerve roots compared with axonal polyneuropathies. With respect to the other nerves, a similar degree of nerve enlargement was observed in both patient groups. These results highlight that ultrasonography may be a complementary tool in differentiating polyneuropathies.

Foaming study combined with physical characterization of aqueous MDEA gas sweetening solutions

This study has been carried out to investigate the foaming behavior of aqueous Methyldiethanolamine (MDEA) in presence of different degradation products and other contaminants as additives. This foaming study was combined with physical characterization of the tested solution to enhance the understanding of the foaming behavior. The foaming tendency of aqueous MDEA solution was reported in terms of foam volume. Foam stability was reported on the basis of the time required for the last bubble to break. The effect of degradation products and heavy and light dissolved organics on solution physical properties i.e. density, surface tension and viscosity were studied. The addition of 2.5 wt% of propionic acid decreased the foam volume by about 4% and the foam stability by about 7.14%, while the heaver organic acids (C5–C7) increased foaming. All organic acids increased the solution viscosity and density and decreased the solution surface tension by various extents. Formaldehyde increased the foaming tendency and enhanced the stability of the foam on MDEA solution. Iron(II) sulfide increased the foaming tendency by about 39.7%, although it decreased the foam stability by about 95.6%. The addition of both pentane and heptane decreased the foaming tendency and stability of the 50 wt% MDEA solution. Finally, a mathematical model was proposed to understand the parametric effects behind the foaming problem of aqueous MDEA solutions and to facilitate the tracking of the sources of foaming and alleviate them or reduce their impact.

Do stand-alone interbody spacers with integrated screws provide adequate segmental stability for multilevel cervical arthrodesis?

Background contextSome postoperative complications after anterior cervical fusions have been attributed to anterior cervical plate (ACP) profiles and the necessary wide operative exposure for their insertion. Consequently, low-profile stand-alone interbody spacers with integrated screws (SIS) have been developed. Although SIS constructs have demonstrated similar biomechanical stability to the ACP in single-level fusions, their role as a stand-alone device in multilevel reconstructions has not been thoroughly evaluated. PurposeTo evaluate the acute segmental stability afforded by an SIS device compared with the traditional ACP in the setting of a multilevel cervical arthrodesis. Study designIn vitro human cadaveric biomechanical analysis. MethodsThirteen human cadaveric cervical spines (C2–T1) were nondestructively tested with a custom 6 df spine simulator under axial rotation, flexion-extension, and lateral bending loading. After intact analysis, eight single-levels (C4–C5/C6–C7) from four specimens were instrumented and tested with ACP and SIS. Nine specimens were tested with C5–C7 SIS, C5–C7 ACP, C4–C7 ACP, C4–C7 ACP+posterior fixation, C4–C7 SIS, and C4–C7 SIS+posterior fixation. Testing order was randomized with each additional level instrumented. Full range of motion (ROM) data were obtained and analyzed by each loading modality, using mean comparisons with repeated measures analysis of variance. Paired t tests were used for post hoc analysis with Sidak correction for multiple comparisons. ResultsNo significant difference in ROM was noted between the ACP and SIS for single-level fixation (p>.05). For multisegment reconstructions (two and three levels), the ACP proved superior to SIS and intact condition, with significantly lower ROM in all planes (p<.05). When either the three-level SIS or ACP constructs were supplemented with posterior lateral mass fixation, there was a greater than 80% reduction in ROM under all testing modalities (p<.05), with no significant difference between the ACP and SIS constructs (p>.05). ConclusionsThe SIS device may be a reasonable option as a stand-alone device for single-level fixation. However, SIS devices should be used with careful consideration in the setting of multilevel cervical fusion. However, when supplemented with posterior fixation, SIS devices are a sound biomechanical alternative to ACP for multilevel fusion constructs.