Using acoustic emission to characterize friction and wear in dry sliding steel contacts

Acoustic emission (AE) was recorded during tribological tests on 52,100 steel specimens under different loads. AE signals were transformed to the frequency domain using a Fast Fourier Transform and parameters such as power, RMS amplitude, mean frequency, and energy were analyzed and compared with friction coefficient and wear volume measurements. Results show that certain acoustic frequencies reflect friction while others reflect wear. If frequencies are chosen optimally, AE and friction signals are highly correlated (Pearson coefficients >0.8). SEM and Raman analysis reveal how plastic deformation and oxide formation affect friction, wear and AE simultaneously. AE recordings contains more information than conventional friction and wear volume measurements and are more sensitive to changes in mechanism. This all demonstrates AE's potential as a tool to monitor tribological behavior.This work was supported by the Overseas Study Program of Jiangsu Higher Education Institutions; the Natural Science Foundation of Jiangsu Province, China (Grant no. BK20160353); the Natural Science Foundation of Jiangsu Higher Education Institutions (Grant no. 16KJB460032); the Key Laboratory of Suzhou (SZS201815); the Top-notch Academic Programs Project of Jiangsu Higher Education Institutions (TAPP) (Grant no. PPZY2015B186) and the Scientific Research Foundation of SIIT (Grant no. 2017kyqd015)

Svježi proizvodi - jogurt, fermentirano mlijeko, sirna masa i svježi sir

Fresh fermented dairy products in general are the oldest milk products. In the early days they were home-made and served as basic food. The introduction of industrial food processing allowed great diversification and a large variety of products is now available to the consumer. The combination of milk, sweet or fermented, with other foods, primarily with fruits and herbs, as well as the development of processes which led to prolongation of the shelf life for up to several months, contributed to the popularity, i.e. to the increase of consumption of these products. According to the latest survey of IDF (1) on the consumption of dairy products in the world, fermented milks are very popular and, with increasing health consciousness of consumers worldwide, new fermented milks are being developed.Potrošnja fermentiranih svježih mliječnih proizvoda naročito jogurta u mnogim je zemljama 1992. bila znatna (podaci IDF). Najhitniji korak u razvoju ovih proizvoda predstavlja primjena selekcioniranih kultura mikroorganizama što je omogućilo bolju kontrolu njihove kvalitete. Uključivanje probiotskih mikroorganizama u kulture za fermentaciju ili dodavanje u samo fermentirano mlijeko najvažnije su modifikacije budućih postupaka proizvodnje. Uvođenje ultrafiltracije u mljekarsku industriju omogućilo je proizvodnju svježeg sira i sirne mase koji sadrže više bjelančevina sirutke. Takvi proizvodi mogu potrošačima stvarati specifične probleme uslijed povećanih količina laktoze i ß-laktoglobulina. Industrijska proizvodnja skute od ovčjeg mlijeka u Sjevernoj Americi je modificirana i proizvodi se od mlijeka smjese sirutke i obranog mlijeka te i/ili dodavanjem praha kisele sirutke. Postupak proizvodnje fermentiranih, svježih mliječnih proizvoda je učinkovita metoda konzerviranja većine prehrambenih, vrijednih sastojaka mlijeka tijekom nekoliko tjedana

Lactobacillus reuteri: novajlija u tehnologiji mlijeka

Lactobacillus reuteri is an inhabitant of the gastrointestinal of humans and animals and has been isolated also from food (sausages, cheese, sour dough). It is suggested that L. reuteri, a dominant heterofermentative Lactobacillus species with unique taits, may interact beneficially in stabilizing the intestinal microflora, thus, having a protective function against pathogenic microorganisms. L. reuteri as a newcomer in dairy technology and products are appearing on the market which are supplemented with this microorganism (sweet milk and fermented milk products). It is not quite clear which role L. reuteri plays in the intestinal ecosystem and how important it is for health and well-being of the host-organism. L. reuteri is an obligatory heterofermentative Lactobacillus and produces under certain conditions reuterin (ß-hydroxypropionaldehyd), a potent broad-spectrum antimicrobial substance acting as inhibitor of a number of undersirable bacteria, yeasts, fungi and protozoa.Lactobacillus reuteri je stanovnik gastrointestinalnog trakta ljudi i Životinja, a izoliranje i iz hrane (kobasice, sir, kiselo tijesto). Navodi se da je L. reuteri dominantna heterofermentativna vrsta Lactobacillus jedinstvenih svojstava. Mote povoljno djelovati na stabiliziranje intestinalne mikroflore, prema tome, štiti od patogenih mikroorganizama. L. reuteri je novajlija u tehnologiji mlijeka i proizvodima koji se pojavljuju na tržištu, a taj se mikroorganizam dodaje (slatko mlijeko i fermentirani mliječni proizvodi). Nije posve jasna uloga L. reuteri u intestinalnom ekosustavu i koliko je važan za zdravlje i dobrobit domaćina. L. reuteri je obligatni heterofermentativni Lactobacillus i proizvodi u određenim uvjetima reuterin (ß-hidroksipropionaldehid), antimikrobnu tvar širokog spektra, koja priječi razvoj niza nepoželjnih bakterija, kvasaca, gljiva i protozoa

Svježi proizvodi - jogurt, fermentirano mlijeko, sirna masa i svježi sir

Fresh fermented dairy products in general are the oldest milk products. In the early days they were home-made and served as basic food. The introduction of industrial food processing allowed great diversification and a large variety of products is now available to the consumer. The combination of milk, sweet or fermented, with other foods, primarily with fruits and herbs, as well as the development of processes which led to prolongation of the shelf life for up to several months, contributed to the popularity, i.e. to the increase of consumption of these products. According to the latest survey of IDF (1) on the consumption of dairy products in the world, fermented milks are very popular and, with increasing health consciousness of consumers worldwide, new fermented milks are being developed.Potrošnja fermentiranih svježih mliječnih proizvoda naročito jogurta u mnogim je zemljama 1992. bila znatna (podaci IDF). Najhitniji korak u razvoju ovih proizvoda predstavlja primjena selekcioniranih kultura mikroorganizama što je omogućilo bolju kontrolu njihove kvalitete. Uključivanje probiotskih mikroorganizama u kulture za fermentaciju ili dodavanje u samo fermentirano mlijeko najvažnije su modifikacije budućih postupaka proizvodnje. Uvođenje ultrafiltracije u mljekarsku industriju omogućilo je proizvodnju svježeg sira i sirne mase koji sadrže više bjelančevina sirutke. Takvi proizvodi mogu potrošačima stvarati specifične probleme uslijed povećanih količina laktoze i ß-laktoglobulina. Industrijska proizvodnja skute od ovčjeg mlijeka u Sjevernoj Americi je modificirana i proizvodi se od mlijeka smjese sirutke i obranog mlijeka te i/ili dodavanjem praha kisele sirutke. Postupak proizvodnje fermentiranih, svježih mliječnih proizvoda je učinkovita metoda konzerviranja većine prehrambenih, vrijednih sastojaka mlijeka tijekom nekoliko tjedana

Validation of prediction models based on lasso regression with multiply imputed data

BACKGROUND: In prognostic studies, the lasso technique is attractive since it improves the quality of predictions by shrinking regression coefficients, compared to predictions based on a model fitted via unpenalized maximum likelihood. Since some coefficients are set to zero, parsimony is achieved as well. It is unclear whether the performance of a model fitted using the lasso still shows some optimism. Bootstrap methods have been advocated to quantify optimism and generalize model performance to new subjects. It is unclear how resampling should be performed in the presence of multiply imputed data. METHOD: The data were based on a cohort of Chronic Obstructive Pulmonary Disease patients. We constructed models to predict Chronic Respiratory Questionnaire dyspnea 6 months ahead. Optimism of the lasso model was investigated by comparing 4 approaches of handling multiply imputed data in the bootstrap procedure, using the study data and simulated data sets. In the first 3 approaches, data sets that had been completed via multiple imputation (MI) were resampled, while the fourth approach resampled the incomplete data set and then performed MI. RESULTS: The discriminative model performance of the lasso was optimistic. There was suboptimal calibration due to over-shrinkage. The estimate of optimism was sensitive to the choice of handling imputed data in the bootstrap resampling procedure. Resampling the completed data sets underestimates optimism, especially if, within a bootstrap step, selected individuals differ over the imputed data sets. Incorporating the MI procedure in the validation yields estimates of optimism that are closer to the true value, albeit slightly too larger. CONCLUSION: Performance of prognostic models constructed using the lasso technique can be optimistic as well. Results of the internal validation are sensitive to how bootstrap resampling is performed

Liquid repellency enhancement through flexible microstructures

Artificial liquid-repellent surfaces have attracted substantial scientific and industrial attention with a focus on creating functional topological features; however, the role of the underlying structures has been overlooked. Recent developments in micro-nanofabrication allow us now to construct a skin-muscle type system combining interfacial liquid repellence atop a mechanically functional structure. Specifically, we design surfaces comprising bioinspired, mushroom-like repelling heads and spring-like flexible supports, which are realized by three-dimensional direct laser lithography. The flexible supports elevate liquid repellency by resisting droplet impalement and reducing contact time. This, previously unknown, use of spring-like flexible supports to enhance liquid repellency provides an excellent level of control over droplet manipulation. Moreover, this extends repellent microstructure research from statics to dynamics and is envisioned to yield functionalities and possibilities by linking functional surfaces and mechanical metamaterials

Validity and responsiveness of the Daily- and Clinical visit-PROactive Physical Activity in COPD (D-PPAC and C-PPAC) instruments

BACKGROUND: The Daily-PROactive and Clinical visit-PROactive Physical Activity (D-PPAC and C-PPAC) instruments in chronic obstructive pulmonary disease (COPD) combines questionnaire with activity monitor data to measure patients' experience of physical activity. Their amount, difficulty and total scores range from 0 (worst) to 100 (best) but require further psychometric evaluation. OBJECTIVE: To test reliability, validity and responsiveness, and to define minimal important difference (MID), of the D-PPAC and C-PPAC instruments, in a large population of patients with stable COPD from diverse severities, settings and countries. METHODS: We used data from seven randomised controlled trials to evaluate D-PPAC and C-PPAC internal consistency and construct validity by sex, age groups, COPD severity, country and language as well as responsiveness to interventions, ability to detect change and MID. RESULTS: We included 1324 patients (mean (SD) age 66 (8) years, forced expiratory volume in 1 s 55 (17)% predicted). Scores covered almost the full range from 0 to 100, showed strong internal consistency after stratification and correlated as a priori hypothesised with dyspnoea, health-related quality of life and exercise capacity. Difficulty scores improved after pharmacological treatment and pulmonary rehabilitation, while amount scores improved after behavioural physical activity interventions. All scores were responsive to changes in self-reported physical activity experience (both worsening and improvement) and to the occurrence of COPD exacerbations during follow-up. The MID was estimated to 6 for amount and difficulty scores and 4 for total score. CONCLUSIONS: The D-PPAC and C-PPAC instruments are reliable and valid across diverse COPD populations and responsive to pharmacological and non-pharmacological interventions and changes in clinically relevant variables

Physical activity is increased by a 12 week semi-automated telecoaching program in patients with COPD, a multicenter randomized controlled trial

Rationale Reduced physical activity (PA) in patients with COPD is associated with a poor prognosis. Increasing PA is a key therapeutic target, but thus far few strategies have been found effective in this patient group. Objectives To investigate the effectiveness of a 12 week semi-automated telecoaching intervention on PA in COPD patients in a multicenter European RCT. Methods 343 patients from 6 centers, including a wide disease spectrum, were randomly allocated to either a usual care group (UCG) or a telecoaching intervention group (IG) between June and December 2014. This 12 weeks intervention included an exercise booklet and a step counter providing feedback both directly and via a dedicated smartphone application. The latter provided an individualized daily activity goal (steps) revised weekly and text messages as well as allowing occasional telephone contacts with investigators. Physical activity was measured using accelerometry during 1 week preceding randomization and during week 12. Secondary outcomes included exercise capacity and health status. Analyses were based on intention-to-treat. Main results Both groups were comparable at baseline in terms of factors influencing PA. At 12 weeks, the intervention yielded a between group difference of mean, 95% [ll-ul] +1469, 95% [971 – 1965] steps.day-1 and +10.4, 95% [6.1 - 14.7] min.day-1 moderate physical activity; favoring the IG (all p≤0.001). The change in six minute walk distance was significantly different (13.4, 95% [3.40 - 23.5]m, p<0.01), favoring the IG. In IG patients an improvement could be observed in the functional state domain of the CCQ (p=0.03), when compared to UCG. Other health status outcomes did not differ. Conclusions The amount and intensity of PA can be significantly increased in COPD patients using a 12 week semi-automated telecoaching intervention including a stepcounter and an application installed on a smartphone

A decision aid to rule out pneumonia and reduce unnecessary prescriptions of antibiotics in primary care patients with cough and fever

BACKGROUND: Physicians fear missing cases of pneumonia and treat many patients with signs of respiratory infection unnecessarily with antibiotics. This is an avoidable cause for the increasing worldwide problem of antibiotic resistance. We developed a user-friendly decision aid to rule out pneumonia and thus reduce the rate of needless prescriptions of antibiotics. METHODS: This was a prospective cohort study in which we enrolled patients older than 18 years with a new or worsened cough and fever without serious co-morbidities. Physicians recorded results of a standardized medical history and physical examination. C-reactive protein was measured and chest radiographs were obtained. We used Classification and Regression Trees to derive the decision tool. RESULTS: A total of 621 consenting eligible patients were studied, 598 were attending a primary care facility, were 48 years on average and 50% were male. Radiographic signs for pneumonia were present in 127 (20.5%) of patients. Antibiotics were prescribed to 234 (48.3%) of patients without pneumonia. In patients with C-reactive protein values below 10 μg/ml or patients presenting with C-reactive protein between 11 and 50 μg/ml, but without dyspnoea and daily fever, pneumonia can be ruled out. By applying this rule in clinical practice antibiotic prescription could be reduced by 9.1% (95% confidence interval (CI): 6.4 to 11.8). CONCLUSIONS: Following validation and confirmation in new patient samples, this tool could help rule out pneumonia and be used to reduce unnecessary antibiotic prescriptions in patients presenting with cough and fever in primary care. The algorithm might be especially useful in those instances where taking a medical history and physical examination alone are inconclusive for ruling out pneumonia