Wear mechanisms description in nanoscale by SEM/TEM of multilayer Zr/ZrN coatings in dependence on phases ratio.

As a result of loading with an external force during the wear process, coating deforms uniformly. After a certain limit load is exceeded, coating deformation is localised through the formation of the so-called shear bands. It has been showed experimentally the process of shear bands formation. The microstructural characterisation before and after the mechanical tests was performed using scanning and transmission electron microscopy (SEM and TEM) on cross-sections of the samples. The analysis indicated that in the case of multilayer coatings where the ratio of the metallic to the ceramic phase is 1:1, the shear bands are formed at an angle of 45°. With a greater proportion of the ceramic phase to metallic (ratio 1:2), the shear band changed the shear angle from ∼45° to ∼90°. Mechanical in situ tests were carried out in the chambers of SEM and TEM. The scratch tests in the SEM were done with the simultaneous observation of the phenomena occurring on the surface of the tested materials showed that at a scratch force of 0.04 N, the additional outer a-C:H layer was damaged, which was shown in the form of a fault in the force-displacement diagram, and in the form of splits visible in the SEM image. However, the application of this additional layer had a positive effect on the wear mechanism of the entire coating structure. The test also indicated that in the case of coatings with phases ratio 1:2 and 1:4 (metallic to ceramic), the characteristics of the brittle material were demonstrated, unlike the coating with a 1:1 phase ratio, where plastic properties predominated. However, for the 1:2 phase ratio coating, the chip was more ductile than for the chip formed when testing a 1:4 phase ratio coating. For in situ mechanical testing in the TEM, a straining holder was used. The test showed that the shear band angle for a 1:1 ratio coating has changed from 45° to 90° due to the different direction of force interaction.

Effect of the mechanical properties of carbon-based coatings on the mechanics of cell-material interactions.

The paper presents an influence of the surface mechanical properties of thin-film materials on blood cell adhesion under shear stress conditions. Physical vapour deposited (PVD) coatings i.e. hydrogenated amorphous carbon (a-C:H) doped with nitrogen or silicon have been investigated. The mechanical properties of materials, namely their microhardness and Young's modulus were measured using indentation test with Rockwell indenter. The adhesion efficiency of blood cells in dynamic conditions were analysed using a radial flow chamber. Red blood cells (RBC) were used as representative cells to analyse cell-material interactions. The biomaterial examinations were performed under physiological flow conditions at the single-cell level. The 3D FVM (finite volume method) model of multi-phase radial flow test was developed to reproduce the physical test and to predict distributions of shear stresses and velocity during blood washout with PBS. Cell-material interactions were found to be strongly associated with the mechanical properties of the thin-film material. The decrease in the hardness of the coatings translated into a weaker cell - material interactions.

Wear mechanisms of the biotribological nanocomposite a-C : H coatings implanted by metallic nanoparticles.

Recently, to reduce the residual stress and increase the mechanical properties of a-C:H coatings, metallic nanoparticles have been implanted into their structure. In the present work, to improve the properties of the coating, metallic nanoparticles, including Cu, Nb, Ta, Zr, AgPt and Ag, were inserted into the a-C:H structure. The applied biological and mechanical analysis allowed the optimal biotribological parameters to be indicated for the potential application as protective coatings for metallic medical tools. Wear mechanisms operating at the small length of the designed biotribological coating, such as a-C:H implanted by Zr nanoparticles, were studied by means of transmission electron microscopy (TEM). The TEM analysis confirmed very good coating adhesion to the metallic substrate.

Emotional awareness and expression training improves irritable bowel syndrome: A randomized controlled trial.

BACKGROUND: Current clinical guidelines identify several psychological treatments for irritable bowel syndrome (IBS). IBS patients, however, have elevated trauma, life stress, relationship conflicts, and emotional avoidance, which few therapies directly target. We tested the effects of emotional awareness and expression training (EAET) compared to an evidence-based comparison condition-relaxation training-and a waitlist control condition. METHODS: Adults with IBS (N=106; 80% female, Mean age=36 years) were randomized to EAET, relaxation training, or waitlist control. Both EAET and relaxation training were administered in three, weekly, 50-minute, individual sessions. All patients completed the IBS Symptom Severity Scale (primary outcome), IBS Quality of Life, and Brief Symptom Inventory (anxiety, depressive, and hostility symptoms) at pretreatment and at 2 weeks posttreatment and 10 weeks follow-up (primary endpoint). KEY RESULTS: Compared to waitlist controls, EAET, but not relaxation training, significantly reduced IBS symptom severity at 10-week follow-up. Both EAET and relaxation training improved quality of life at follow-up. Finally, EAET did not reduce psychological symptoms, whereas relaxation training reduced depressive symptoms at follow-up (and anxiety symptoms at posttreatment). CONCLUSIONS & INFERENCES: Brief emotional awareness and expression training that targeted trauma and emotional conflicts reduced somatic symptoms and improved quality of life in patients with IBS. This emotion-focused approach may be considered an additional treatment option for IBS, although research should compare EAET to a full cognitive-behavioral protocol and determine which patients are best suited for each approach. Registered at clinicaltrials.gov (NCT01886027).

Microstructure characterization of advanced protective Cr/CrN+a-C:H/a-C:H:Cr multilayer coatings on carbon fibre composite (CFC).

Studies of advanced protective chromium-based coatings on the carbon fibre composite (CFC) were performed. Multidisciplinary examinations were carried out comprising: microstructure transmission electron microscopy (TEM, HREM) studies, micromechanical analysis and wear resistance. Coatings were prepared using a magnetron sputtering technique with application of high-purity chromium and carbon (graphite) targets deposited on the CFC substrate. Selection of the CFC for surface modification in respect to irregularities on the surface making the CFC surface more smooth was performed. Deposited coatings consisted of two parts. The inner part was responsible for the residual stress compensation and cracking initiation as well as resistance at elevated temperatures occurring namely during surgical tools sterilization process. The outer part was responsible for wear resistance properties and biocompatibility. Experimental studies revealed that irregularities on the substrate surface had a negative influence on the crystallites growth direction. Chromium implanted into the a-C:H structure reacted with carbon forming the cubic nanocrystal chromium carbides of the Cr23 C6 type. The cracking was initiated at the coating/substrate interface and the energy of brittle cracking was reduced because of the plastic deformation at each Cr interlayer interface. The wear mechanism and cracking process was described in micro- and nanoscale by means of transmission electron microscope studies. Examined materials of coated CFC type would find applications in advanced surgical tools.

Gender differences in irritable bowel syndrome: the interpersonal connection.

BACKGROUND: While irritable bowel syndrome (IBS) affects women more than men, the reasons are unclear. Research on the female preponderance of IBS has focused on gender differences in sex-linked biological processes; much less attention has been paid to the role of psychosocial factors. Interpersonal difficulties may be one source of stress that may significantly impact on women with IBS. Because of the importance that women attach to relationships, we suspected they would be more reactive to interpersonal stress. METHODS: A total of 283 (M age = 41 years, F = 80%), Rome III-diagnosed IBS patients completed a test battery that included the IBS Symptom Severity Scale, McGill Pain Questionnaire, Inventory of Interpersonal Problems (IIP), interpersonal support evaluation list (social support), Negative Interactions Scale, Brief Symptom Inventory (distress), Beck Depression Inventory, Anxiety Sensitivity Inventory, and IBS-Quality of Life as part of baseline assessment of an NIH trial. KEY RESULTS: Males scored higher on two IIP scales reflecting a hostile-dominant interpersonal pattern, and reported less social support. The quality of relationship problems (more interpersonal difficulties, lower support) correlated with IBS symptom severity as measured mainly by gastroenterologists. CONCLUSIONS & INFERENCES: Male, not female, IBS patients reported more interpersonal difficulties. Male patients-a population for whom little is known-are characterized by hostile-dominant interpersonal problems. This finding has clinical importance, given that relationship problems may influence MDs' estimation of IBS symptom severity and undermine the physician-patient relationship.

The accuracy of patient-reported measures for GI symptoms: a comparison of real time and retrospective reports.

BACKGROUND: Obtaining accurate information about gastrointestinal (GI) symptoms is critical to achieving the goals of clinical research and practice. The accuracy of patient data is especially important for functional GI disorders (e.g., IBS) whose symptoms lack a biomarker and index illness severity and treatment response. Retrospective patient-reported data are vulnerable to forgetting and various cognitive biases whose impact has not been systematically studied in patients with GI disorders. The aim of this study was to document the accuracy of patient-reported GI symptoms over a reporting period (1 week) most representative of the time frame used in research and clinical care. METHODS: Subjects were 273 Rome III-diagnosed IBS patients (mean age = 39 years, 89% F) who completed end of day GI symptom ratings for 7 days using an electronic diary. On Day 8, Subjects recalled the frequency and/or intensity of IBS symptoms over the past 7 days. Reports were then compared against a validation criterion based on aggregated end of day ratings. KEY RESULTS: At the group level, subjects recalled most accurately abdominal pain and urgency intensity at their worst, urgency days, and stool frequency. When data were analyzed at the individual level, a subgroup of subjects had difficulty recalling accurately symptoms that showed convergence between recall and real time reports at the group level. CONCLUSIONS & INFERENCES: Although many patients' recollection for specific GI symptoms (e.g., worst pain, stool frequency) is reasonably accurate, a non-trivial number of other symptoms (e.g., typical pain) are vulnerable to distortion from recall biases that can reduce sensitivity of detecting treatment effects in clinical and research settings.

The ties that bind: perceived social support, stress, and IBS in severely affected patients.

BACKGROUND: This study assessed the association between social support and the severity of irritable bowel syndrome (IBS) symptoms in a sample of severely affected IBS patients recruited to an NIH-funded clinical trial. In addition, we examined if the effects of social support on IBS pain are mediated through the effects on stress. METHODS: Subjects were 105 Rome II diagnosed IBS patients (F = 85%) who completed seven questionnaires which were collected as part of a pretreatment baseline assessment. KEY RESULTS: Partial correlations were conducted to clarify the relationships between social support and clinically relevant variables with baseline levels of psychopathology, holding constant number of comorbid medical diseases, age, gender, marital status, ethnicity, and education. Analyses indicated that social support was inversely related to IBS symptom severity. Social support was positively related with less severe pain. A similar pattern of data was found for perceived stress but not quality of life impairment. Regression analyses examined if the effects of social support on pain are mediated by stress. The effects of social support on bodily pain were mediated by stress such that the greater the social support the less stress and the less pain. This effect did not hold for symptom severity, quality of life, or psychological distress. CONCLUSIONS & INFERENCES: This study links the perceived adequacy of social support to the global severity of symptoms of IBS and its cardinal symptom (pain). It also suggests that the mechanism by which social support alleviates pain is through a reduction in stress levels.

Motility of the antroduodenum in healthy and gastroparetics characterized by wireless motility capsule.

BACKGROUND: The wireless motility capsule (WMC) measures intraluminal pH and pressure, and records transit time and contractile activity throughout the gastrointestinal tract. Our hypothesis is that WMC can differentiate antroduodenal pressure profiles between healthy people and patients with upper gut motility dysfunctions. This study aims to analyze differences in the phasic pressure profiles of the stomach and small intestine in healthy and gastroparetic subjects. METHODS: Data from 71 healthy and 42 gastroparetic subjects were analyzed. The number of contractions (Ct), area under the pressure curve and motility index (MI = Ln (Ct *sum amplitudes +1)) were analyzed for 60 min before gastric emptying of the capsule (GET), (gastric window) and after GET (small bowel window) and results between groups were compared with the Wilcoxon rank sum test. KEY RESULTS: Significant differences were observed between healthy and gastroparetic subjects for Ct and MI (P < 0.05). Median values of the motility parameters in gastric window were Ct = 72, MI = 11.83 for healthy and Ct = 47, MI = 11.12 for gastroparetics. In the small bowel, median values were Ct = 144.5, MI = 12.78 for healthy and Ct = 93, MI = 12.12 for gastroparetics. Diabetic subjects with gastroparesis showed significantly lower Ct and MI compared with healthy subjects in both gastric and small bowel windows while idiopathic gastroparetic subjects did not show significant differences. CONCLUSIONS & INFERENCES: The WMC is able to differentiate between healthy and gastroparetic subjects based on gastric and small bowel motility profiles.

The assessment of regional gut transit times in healthy controls and patients with gastroparesis using wireless motility technology.

BACKGROUND: Wireless pH and pressure motility capsule (wireless motility capsule) technology provides a method to assess regional gastrointestinal transit times. AIMS: To analyse data from a multi-centre study of gastroparetic patients and healthy controls and to compare regional transit times measured by wireless motility capsule in healthy controls and gastroparetics (GP). METHODS: A total of 66 healthy controls and 34 patients with GP (15 diabetic and 19 idiopathic) swallowed wireless motility capsule together with standardized meal (255 kcal). Gastric emptying time (GET), small bowel transit time (SBTT), colon transit time (CTT) and whole gut transit time (WGTT) were calculated using the wireless motility capsule. RESULTS: Gastric emptying time, CTT and WGTT but not SBTT were significantly longer in GP than in controls. Eighteen percent of gastroparetic patients had delayed WGTT. Both diabetic and idiopathic aetiologies of gastroparetics had significantly slower WGTT (P < 0.0001) in addition to significantly slower GET than healthy controls. Diabetic gastroparetics additionally had significantly slower CTT than healthy controls (P = 0.0054). CONCLUSIONS: In addition to assessing gastric emptying, regional transit times can be measured using wireless motility capsule. The prolongation of CTT in gastroparetic patients indicates that dysmotility beyond the stomach in GP is present, and it could be contributing to symptom presentation.

Comparison of gastric emptying of a nondigestible capsule to a radio-labelled meal in healthy and gastroparetic subjects.

BACKGROUND: Gastric emptying scintigraphy (GES) using a radio-labelled meal is used to measure gastric emptying. A nondigestible capsule, SmartPill, records luminal pH, temperature, and pressure during gastrointestinal transit providing a measure of gastric emptying time (GET). AIMS: To compare gastric emptying time and GES by assessing their correlation, and to compare GET and GES for discriminating healthy subjects from gastroparetics. METHODS: Eighty-seven healthy subjects and 61 gastroparetics enrolled with simultaneous SmartPill and GES. Fasted subjects were ingested capsule and [(99m)Tc]-SC radio-labelled meal. Images were obtained every 30 min for 6 h. Gastric emptying time and percentage of meal remaining at 2/4 h were determined for each subject. The sensitivity/specificity and receiver operating characteristic analysis of each measure were determined for each subject. RESULTS: Correlation between GET and GES-4 h was 0.73 and GES-2 h was 0.63. The diagnostic accuracy from the receiver operating characteristic curve between gastroparetics and healthy subjects was GET = 0.83, GES-4 h = 0.82 and GES-2 h = 0.79. The 300-min cut-off time for GET gives sensitivity of 0.65 and specificity of 0.87 for diagnosis of gastroparesis. The corresponding sensitivity/specificity for 2 and 4 h standard GES measures were 0.34/0.93 and 0.44/0.93, respectively. CONCLUSION: SmartPill GET correlates with GES and discriminates between healthy and gastroparetic subjects offering a nonradioactive, standardized, ambulatory alternative to scintigraphy.

Advances and problems with TEM characterization of Cr/CrN multilayer coatings.

Multilayer Cr/CrN/Cr/Cr(N,C) and Cr/CrN with 8 and 32 layer coatings were deposited on austenite substrates using pulsed laser deposition (PLD) technique. The microstructure observations were performed using Philips CM20trade mark, TECNAI G(2) F20 - TWINtrade mark and JEOL EX4000trade mark transmission microscopes. The performed experiments indicated that lowering the argon flow from 60 to 30 cm(3)/s during chromium ablation changes buffer layers microstructure from nearly amorphous to nano-crystalline. The nitride or carbo-nitride layers turned out to be less sensitive to changes in nitrogen flow during deposition. The columnar microstructure of Cr layers is coarser than those in CrN ones under the same deposition condition. This observation proved also that relying on PLD technique as thin as 30 nm layers might be formed within multilayer Cr/CrN coatings.

Specificity of Stroop interference in patients with pain and PTSD.

The authors investigated processing of threat words in motor vehicle accident survivors using a modified Stroop procedure. Three samples were included: 28 participants with comorbid posttraumatic stress disorder (PTSD) and pain, 26 participants with pain without PTSD, and 21 participants without pain or any psychiatric conditions. Four word categories were used: (a) accident words, (b) pain words, (c) positive words, and (d) neutral words. This study examined whether processing biases would occur to accident words only in participants with PTSD or if these biases would also be noted in the No PTSD/Pain sample. Additionally, this study examined whether processing biases would be noted to pain words in the 2 pain samples, irrespective of PTSD. Overall, color naming was significantly slower in the PTSD/Pain group in comparison with the other groups. As well, the PTSD/Pain sample showed significant response delays to both accident and pain-related words, whereas patients with No PTSD/Pain showed delays to pain stimuli only.

The relative influence of perceived pain control, anxiety, and functional self efficacy on spinal function among patients with chronic low back pain.

STUDY DESIGN: A prospective analysis of the relative influence of pain-specific and performance-specific cognitive variables on lifting tasks using empirically derived measures. OBJECTIVES: To determine the relative contributions of self efficacy expectancies of lifting performance, perceptions of pain control, and anxiety on actual lifting performance. SUMMARY OF BACKGROUND INFORMATION: Although patients' pain beliefs play an important role in the expression of low back pain, there is little research on the influence of performance-specific cognitions on spinal function. This study extended the scope of recent research, with findings indicating that patients with a stronger functional self efficacy expectancy--the belief that one can perform essential work tasks successfully--achieve higher levels of function than those with a low functional self efficacy expectancy. Moreover, as a performance-specific variable, functional self efficacy expectancy was hypothesized to be a better predictor of lifting than pain-specific cognitions, which presumably influence function in an indirect manner, if at all. METHODS: Before undergoing a standardized, graded lifting assessment, 100 work-disabled patients with chronic back pain rated their confidence to perform load-lifting tasks essential to their job (functional self efficacy expectancy), their ability to control and decrease pain, and psychological distress. RESULTS: Multiple regression analyses found that functional self efficacy expectancy accurately predicted lifting. It was found to be a better predictor of lifting tasks than either of the perceived pain control measures or psychological distress. CONCLUSION: Data suggest that what patients believed they could achieve accurately determined their actual spinal function, independent of their sense of control over pain or their distress. Approaches to low back disorders emphasizing perceived pain control as a central cognitive determinant of disability were unsupported.