Monitoring joint quality: Taguchi approach and structure investigation

Purpose

This paper aims to monitor, evaluate and adjust the joint quality of dissimilar friction stir welded AA2024-T3 and AA7075-T6 Al alloys.

Design/methodology/approach

Taguchi analysis for design of experiments and ANOVA analysis were applied. Tensile test, visual inspection and macro and microstructure investigations were carried out at each welding condition. In addition, the grain size of stir zone and the value of heat input were measured.

Findings

Using Taguchi analysis, the optimum values of tool rotary speed, welding speed and axial load were 1,200 rpm, 100 mm/min and 1,300 kg, respectively, yielding the maximum tensile strength of the joints of 427 MPa. ANOVA analysis indicated that the most significant parameter on the joint strength is the tool rotary speed, followed by welding speed and axial load, with contributions of 67, 27 and 2 per cent, respectively. Best mixing between Al alloys in the stir zone with no defects was observed at moderate speeds because of proper heat input and grain size, resulting in high strength.

Originality/value

A relation between structure characteristics of the joint, the process parameters and the joint strength was established to control the joint quality.

Tissue Processing for Stereological Analyses of Lung Structure in Chronic Obstructive Pulmonary Disease

Quantitative data on lung structure, such as volume, surface area and length, are used for assessment of the functional performance of the lung during normal development and inflammatory-related diseases such as chronic obstructive pulmonary disorder (COPD), and carcinogenesis, in animal models. Stereology is considered as the gold standard to obtain quantitative data on lung structure, with a key advantage being to quantify irregular three-dimensional structures on the basis of measurement made on two-dimensional sections. Therefore, preservation of original tissue dimensions without shrinkage is vital for stereology.Three steps, fixation, sampling and embedding, are essential requirements to minimise tissue shrinkage to obtain theoretically unbiased estimates of stereological parameters of lung structures. Perfusion fixation by intratracheal instillation with 1.5% glutaraldehyde/1.5% formaldehyde at a pressure of 25 cm fluid column is considered as one of the best methods. A systematic uniform random sampling scheme is then applied to the fixed lung to ensure each and every part of the lung is analysed, irrespective of homogeneity or heterogeneity of the structural distribution. The sampled tissue sections are then embedded in glycol methacrylate to minimise further tissue shrinkage. Here we describe the accurate fixation, sampling and embedding for stereological methods to quantify lung structures in mice.

Rapid in situ imaging and whole genome sequencing of biofilm in neonatal feeding tubes: A clinical proof of concept

The bacterial flora of nasogastric feeding tubes and faecal samples were analysed for a low-birth weight (725 g) neonate EGA 25 weeks in intensive care. Samples were collected at age 6 and 8 weeks of life. Optical coherence tomography (OCT) was used to visualise bacterial biofilms inside the nasogastric feeding tubes. The biofilm was heterogeneously distributed along the tube lumen wall, and had a depth of up to 500 µm. The bacterial biofilm and faecal samples included Enterococcus faecalis and Enterobacter hormaechei. Representative strains, recovered from both feeding tubes and faecal samples, were whole genome sequenced using Illumina, Mi-Seq, which revealed indistinguishable strains, each with less than 28 SNP differences, of E. faecalis and E. hormaechei. The E. faecalis strains were from two sequence types (ST191 and ST211) and encoded for a number of traits related to biofilm formation (BopD), adherence (Epb pili), virulence (cps loci, gelatinase, SprE) and antibiotic resistances (IsaA, tetM). The E. hormaechei were all ST106, and encoded for blaACT-15 β–lactamase and fosfomycin resistance (fosA). This proof of concept study demonstrates that bacterial flora within the neonatal feeding tubes may influence the bacterial colonisation of the intestinal tract and can be visualised non-destructively using OCT.

Hypertrophic osteoarthropathy in a young adult male from Berber, Sudan (2nd-3rd century CE)

Hypertrophic osteoarthropathy (HOA) is a pathological condition characterised by extensive periosteal new bone formation (NBF) on the diaphyses of the long bones, metacarpal and metatarsal bones. In modern clinical contexts, the secondary form of the disease is common and most often occurs secondary to intra-thoracic cancer and other forms of chronic pulmonary disease. Paleopathological evidence for HOA on the other hand has only occasionally been reported. Here we report a young adult male from the Meriotic cemetery at Berber in Sudan (2nd-3rd century CE) displaying widespread NBF on the diaphyses of the upper and lower limb bones, metacarpal and metatarsal bones, as well as the pelvis and scapulae. While several pathological conditions have to be considered as differential diagnostic options for NBF in the post-cranial skeleton, HOA is the most likely diagnosis, based on the distribution of the changes observed in this individual, as well as their macroscopic and radiographic characteristics. A chronic pulmonary condition as indicated by NBF on the visceral side of the ribs may represent the underlying cause for the HOA. This individual represents the first paleopathological case of HOA reported from an archaeological site in Africa.

Enteral nutrition as stress ulcer prophylaxis in critically ill patients: A randomized controlled exploratory study

PURPOSE

We investigated whether early enteral nutrition alone may be sufficient prophylaxis against stress-related gastrointestinal (GI) bleeding in mechanically ventilated patients.

MATERIALS AND METHODS

Prospective, double blind, randomized, placebo-controlled, exploratory study that included mechanically ventilated patients in medical ICUs of two academic hospitals. Intravenous pantoprazole and early enteral nutrition were compared to placebo and early enteral nutrition as stress-ulcer prophylaxis. The incidences of clinically significant and overt GI bleeding were compared in the two groups.

RESULTS

124 patients were enrolled in the study. After exclusion of 22 patients, 102 patients were included in analysis: 55 patients in the treatment group and 47 patients in the placebo group. Two patients (one from each group) showed signs of overt GI bleeding (overall incidence 1.96%), and both patients experienced a drop of >3 points in hematocrit in a 24-hour period indicating a clinically significant GI bleed. There was no statistical significant difference in the incidence of overt or significant GI bleeding between groups (p=0.99).

CONCLUSION

We found no benefit when pantoprazole is added to early enteral nutrition in mechanically ventilated critically ill patients. The routine prescription of acid-suppressive therapy in critically ill patients who tolerate early enteral nutrition warrants further evaluation.

Viral infection in community-acquired pneumonia: a systematic review and meta-analysis

The advent of PCR has improved the identification of viruses in patients with community-acquired pneumonia (CAP). Several studies have used PCR to establish the importance of viruses in the aetiology of CAP.We performed a systematic review and meta-analysis of the studies that reported the proportion of viral infection detected via PCR in patients with CAP. We excluded studies with paediatric populations. The primary outcome was the proportion of patients with viral infection. The secondary outcome was short-term mortality.Our review included 31 studies. Most obtained PCR via nasopharyngeal or oropharyngeal swab. The pooled proportion of patients with viral infection was 24.5% (95% CI 21.5-27.5%). In studies that obtained lower respiratory samples in >50% of patients, the proportion was 44.2% (95% CI 35.1-53.3%). The odds of death were higher in patients with dual bacterial and viral infection (OR 2.1, 95% CI 1.32-3.31).Viral infection is present in a high proportion of patients with CAP. The true proportion of viral infection is probably underestimated because of negative test results from nasopharyngeal or oropharyngeal swab PCR. There is increased mortality in patients with dual bacterial and viral infection.

The Interaction of Risk Network Structures and Virus Natural History in the Non-spreading of HIV Among People Who Inject Drugs in the Early Stages of the Epidemic

This article explores how social network dynamics may have reduced the spread of HIV-1 infection among people who inject drugs during the early years of the epidemic. Stochastic, discrete event, agent-based simulations are used to test whether a "firewall effect" can arise out of self-organizing processes at the actor level, and whether such an effect can account for stable HIV prevalence rates below population saturation. Repeated simulation experiments show that, in the presence of recurring, acute, and highly infectious outbreaks, micro-network structures combine with the HIV virus's natural history to reduce the spread of the disease. These results indicate that network factors likely played a significant role in the prevention of HIV infection within injection risk networks during periods of peak prevalence. They also suggest that social forces that disturb network connections may diminish the natural firewall effect and result in higher rates of HIV.

Exfoliation of graphene sheets via high energy wet milling of graphite in 2-ethylhexanol and kerosene

Graphene sheets have been exfoliated from bulk graphite using high energy wet milling in two different solvents that were 2-ethylhexanol and kerosene. The milling process was performed for 60 h using a planetary ball mill. Morphological characteristics were investigated using scanning electron microscope (SEM) and transmission electron microscope (TEM). On the other hand, the structural characterization was performed using X-ray diffraction technique (XRD) and Raman spectrometry. The exfoliated graphene sheets have represented good morphological and structural characteristics with a valuable amount of defects and a good graphitic structure. The graphene sheets exfoliated in the presence of 2-ethylhexanol have represented many layers, large crystal size and low level of defects, while the graphene sheets exfoliated in the presence of kerosene have represented fewer number of layers, smaller crystal size and higher level of defects.

Anomalous nonradiative decay in Dy-doped glasses and crystals

Nonradiative relaxation in Dy-doped fluoroindate glass is measured and characterized in terms of the well-known exponential energy gap law. It is found that although three low-lying Dy transitions fit well with an exponential dependence on an energy gap, the overall magnitude of the Dy decay rate is an order of magnitude higher than that of other rare earth ions. It is also found that the nonradiative decay rates in InF₃ glass are comparable to those in ZrF₄ glass, contrary to expectations based on maximum phonon energy. These unexpected results have important implications for a potential 4 μm Dy:InF₃ fiber laser.

Open and closed models of intensive care unit have different influences on infectious complications in a tertiary care center: A retrospective data analysis

Infectious complications in the intensive care unit (ICU) are associated with higher morbidity, mortality, and increased health care use. Here, we report the results of implementing 2 different models (open vs closed) on infectious complications in the ICU. The closed ICU model was associated with 52% reduction in ventilator-associated pneumonia rate (P = .038) and 25% reduction in central line-associated bloodstream infection rate (P = .631). We speculate that a closed ICU model allows clinical leadership centralization that further facilitates standardized care delivery that translates into fewer infectious complications.