Nanotribological and wetting performance of hierarchical patterns.

Surface modification is a promising method to solve the tribological problems in microsystems. To modify the surface, we fabricated hierarchical patterns with different pitches of nano-scale features and different surface chemistries. Micro- and nano-patterns with similar geometrical configurations were also fabricated for comparison. The nano-tribological behavior of the patterns was investigated using an atomic force microscope at different relative humidity levels (5% to 80%) and applied normal loads (40 nN to 120 nN) under a constant sliding velocity. The results showed significant enhancement in the de-wetting and tribological performance of the hierarchical patterns compared with those of flat and micro- and nano-patterned surfaces. The PTFE-coated hierarchical patterns showed similar dynamic contact angles (advancing and receding) to those of the real lotus leaf. The influence of relative humidity on adhesion and friction behavior was found to be significant for all the tested surfaces. The tribological performance was improved as the pitch of the nano-scale geometry of the hierarchical pattern increased, even though the wetting property was not influenced significantly. A model was proposed based on the role of intermolecular force to explain the effect of the pitch of the hierarchical patterns on the adhesion and friction behavior. According to the model based on the molecular force, the contact between a ball and the patterned surface was a multi-asperity contact, contrary to the single-asperity contact predicted by the Johnson-Kendall-Roberts (JKR) and Maugis-Dugdale (MD) models. The strong intermolecular forces, which are activated in the confined spaces between the adjacent nano-pillars and the ball, contributed to the contact area and hence the adhesion and friction forces.

Concordant or discordant results by the tuberculin skin test and the quantiFERON-TB test in children reflect immune biomarker profiles.

The tuberculin skin test (TST) and QuantiFERON-TB-Gold-In-tube (QFTGIT) are adjunctive tests used in the diagnosis of pediatric tuberculosis (TB). Neither test can rule out TB; however, a positive test usually triggers preventive treatment in TB contacts aged <5 years. TST and QFTGIT can give divergent results and it is unclear how discordant results should be interpreted in terms of TB risk and preventive treatment. To understand the immune processes underlying concordant or discordant TST and QFTGIT results, we analyzed immune responses in children from Palamaner Taluk in India (a TB-endemic region with routine neonatal BCG vaccination) who were referred to a TB case verification ward on suspicion of TB. Two hundred and ten children aged <3 years were classified according to their TST and QFTGIT results, and their immune responses analyzed by dual-colour-Reverse-Transcriptase-Multiple-Ligation-dependent-Probe-Amplification, using a panel of 45 genes and a 10-plex antigen-specific enzyme-linked immunosorbent assay. We show that immune biomarkers FPR1, TNFRSF1A and interferon (IFN)-γ are upregulated (all P<0.05) in concordant test-positive children, whereas BPI is downregulated (P<0.05). In contrast, SEC14L1 (P=0.034) and Interferon gamma-induced protein 10 (IP-10) (P=0.001) are differentially expressed between the TST+QFTGIT- /TST-QFTGIT+ groups. Known TB exposure was more frequent in concordant positive children and results were consistent with elevated expression of genes associated with inflammatory responses. Children with discordant test results displayed a mixed profile with activation of both pro- and anti-inflammatory markers. TST and/or QFTGIT positivity appears to reflect distinct but overlapping aspects of host immunity.

Identification of biomarkers for Mycobacterium tuberculosis infection and disease in BCG-vaccinated young children in Southern India.

Pediatric tuberculosis (TB) often goes undiagnosed because of the lack of reliable diagnostic methods. With the aim of assessing biomarker(s) that can aid in the diagnosis of TB infection and disease, we investigated 746 Indian children with suspected TB. Whole-blood mRNA from 210 children was examined by dual-color Reverse-Transcriptase Multiple Ligation-dependent Probe-Amplification for the expression of 45 genes and a Bio-Plex assay for the expression of cytokines/chemokines in QuantiFERON supernatants. The study shows that transcription of SEC14L1, GUSB, BPI, CCR7 and TGFß-1 (all P ≤ 0.05) was downregulated in TB disease compared with uninfected controls, while transcription of RAB33A was downregulated in TB disease compared with both latent TB (P < 0.05) and controls (P < 0.01). The transcription of CD4, TGFß-1 (P < 0.01) and the expression of IL-2 (P < 0.01) and IL-13 (P < 0.05) was upregulated in latent TB compared with that in controls. Using the Least Absolute Shrinkage and Selection Operator (lasso) model, RAB33A alone discriminated between TB disease and latent TB (area under the curve (AUC) 77.5%), whereas a combination of RAB33A, CXCL10, SEC14L1, FOXP3 and TNFRSF1A was effective in discriminating between TB disease and controls (AUC 91.7%). A combination of 11 biomarkers predicted latent TB with moderate discriminatory power (AUC 72.2%). In conclusion, RAB33A is a potential biomarker for TB disease, whereas CD4, TGFß-1 and IL-2, IL-13 may identify latent TB in children.

Mycobacterium tuberculosis Mce1 protein complex initiates rapid induction of transcription of genes involved in substrate trafficking.

The mammalian cell entry (Mce)1 protein complex has an important role during the initial phase of a Mycobacterium tuberculosis (M. tuberculosis) infection. Murine macrophages were infected with M. tuberculosis H37Rv or Δ-mce1 H37Rv, and total RNA was isolated from the host cells at 15, 30 and 60 min, and 4 and 10 h post-infection. With the aim of studying the role for the Mce1 protein complex on host gene expression, the RNA was hybridized onto 44 K whole-genome microarrays. Selected genes were verified by reverse-transcriptase quantitative PCR (RT-QPCR). 'Transport' was the most overrepresented biological process during the first hour post H37Rv infection. Five genes (Abca1 (21.0-fold), Slc16a10 (3.1-fold), Slc6a12 (17.9-fold), Slc6a8 (2.3-fold) and Nr1h3, (5.5-fold)) involved in substrate trafficking were verified by RT-QPCR to be upregulated by >2-fold 1 h post H37Rv infection. By 1 h post Δ-mce1 H37Rv infection, only Abca1 and Slc6a12 were upregulated by >2-fold. A number of other genes, which may be directly involved in substrate trafficking or share the same transcription, were found to have expression profiles similar to the genes involved in substrate trafficking. The Mce1 protein complex has a significant role in the transcriptional activation of genes involved in substrate trafficking during the initial phase of an M. tuberculosis infection.

Rapid syndromic PCR testing in patients with respiratory tract infections reduces time to results and improves microbial yield.

Lack of rapid and comprehensive microbiological diagnosis in patients with community acquired pneumonia (CAP) hampers appropriate antimicrobial therapy. This study evaluates the real-world performance of the BioFire FilmArray Pneumonia panel plus (FAP plus) and explores the feasibility of evaluation in a randomised controlled trial. Patients presenting to hospital with suspected CAP were recruited in a prospective feasibility study. An induced sputum or an endotracheal aspirate was obtained from all participants. The FAP plus turnaround time (TAT) and microbiological yield were compared with standard diagnostic methods (SDs). 96/104 (92%) enrolled patients had a respiratory tract infection (RTI); 72 CAP and 24 other RTIs. Median TAT was shorter for the FAP plus, compared with in-house PCR (2.6 vs 24.1 h, p < 0.001) and sputum cultures (2.6 vs 57.5 h, p < 0.001). The total microbiological yield by the FAP plus was higher compared to SDs (91% (162/179) vs 55% (99/179), p < 0.0001). Haemophilus influenzae, Streptococcus pneumoniae and influenza A virus were the most frequent pathogens. In conclusion, molecular panel testing in adults with CAP was associated with a significant reduction in time to actionable results and increased microbiological yield. The impact on antibiotic use and patient outcome should be assessed in randomised controlled trials.

Posterior neonatal teeth.

Teeth which are present in the oral cavity of newborn infant at the time of birth are called "natal teeth" and which erupts in first month of postnatal life are called as "neonatal teeth." The incidence of these teeth is 1 in 2000 to 1 in 3500 live birth. The most common natal teeth reported are mandibular central incisors followed by maxillary incisors and mandibular canine. The natal or neonatal tooth in maxillary molar region is a rare occurrence. This article represents a rare case of bilateral neonatal maxillary molar teeth.

Evaluation of a personal protective equipment support programme for staff during the COVID-19 pandemic in London.

BACKGROUND: The coronavirus disease 2019 pandemic has presented an enormous challenge to healthcare providers worldwide. The appropriate use of personal protective equipment (PPE) has been essential to ensure staff and patient safety. The 'PPE Helper Programme' was developed at a large London hospital group to counteract suboptimal PPE practice. Based on a behaviour change model of capability, opportunity and motivation (COM-B), the programme provided PPE support, advice and education to ward staff. AIM: Evaluation of the PPE Helper Programme. METHODS: Clinical and non-clinical ward staff completed a questionnaire informed by the Theoretical Domains Framework and COM-B model. The questionnaire was available in paper and electronic versions. Quantitative responses were analysed using descriptive and non-parametric statistics, and free-text responses were analysed thematically. FINDINGS: Over a 6-week period, PPE helpers made 268 ward visits. Overall, 261 questionnaires were available for analysis. Across the Trust, 68% of respondents reported having had contact with a PPE helper. Staff who had encountered a PPE helper responded significantly more positively to a range of statements about using PPE than staff who had not encountered a PPE helper. Black and minority ethnic staff were significantly more anxious regarding the adequacy of PPE. Non-clinical and redeployed staff (e.g. domestic staff) were most positive about the impact of PPE helpers. Free-text comments showed that staff found the PPE Helper Programme supportive and would have liked it earlier in the pandemic. CONCLUSION: The PPE Helper Programme is a feasible and beneficial intervention for providing support, advice and education to ward staff during infectious disease outbreaks.

Enhanced durability, bio-activity and corrosion resistance of stainless steel through severe surface deformation.

Owing to its good biocompatibility and low cost, stainless steel is one of the most widely utilized biomaterial. However, longtime assessment of stainless steel has shown problems related to material degradation, especially localized corrosion and bio-film formation. In addition, the leaching of toxic nickel and chromium ions from stainless steel leads to additional health complications. Here, we utilized submerged friction stir processing, a severe surface deformation technique for significantly enhancing its durability, bio-activity as well as antibacterial resistance. The processing was done with a wide variation in strain rates to produce tunable surface microstructure. High strain-rate processing resulted in nearly single-phase fine-grained microstructure, while slow strain-rate processing developed a dual-phase fine-grained microstructure. The bio-corrosion rate of processed steel was reduced by more than 60 % along with significant enhancement in the pitting resistance. The processed steel showed nearly no bacterial adhesion/biofilm formation, evaluated using S. aureus and E. coli bacterial strains. Further, the processed stainless steel surface demonstrated minimum leaching of the toxic elements, significantly enhancing its appeal for bio-implant applications. The observed behavior was explained based on the formation of a stable passive layer, rich in Cr2O3, as determined using x-ray photoelectron microscopy (XPS) and increased hydrophilicity.

Direct detection of mycobacterial species in pulmonary specimens by two rapid amplification tests, the gen-probe amplified mycobacterium tuberculosis direct test and the genotype mycobacteria direct test.

Nucleic acid amplification tests have improved tuberculosis diagnostics considerably. This study evaluates a new amplification test, the GenoType Mycobacteria Direct (GTMD) test, for detection of the Mycobacterium tuberculosis complex, Mycobacterium avium, Mycobacterium intracellulare, Mycobacterium kansasii, and Mycobacterium malmoense directly in 61 sputum samples. Thirty (49.2%) samples were auramine smear positive, and 31 (50.8%) were smear negative. The GTMD results were compared to the Gen-Probe Amplified M. tuberculosis Direct (MTD) test results, using culturing and sequencing of the 16S rRNA gene as reference methods. The GTMD test could identify 28 of 29 samples containing the M. tuberculosis complex and was negative in a sputum sample containing M. intracellulare. The overall sensitivity and specificity results were 93.3% and 90.0% for the GTMD test, respectively, and 93.1% and 93.5% for the MTD test, respectively. The GTMD test is rapid and can be easily included in routine clinical laboratories for the direct detection of the M. tuberculosis complex in smear-positive sputum samples as an adjunct to microscopy and culture. Further studies are needed to evaluate the performance of the GTMD test for the detection of atypical mycobacteria.

Prevalence of dental caries and treatment needs in the rural child population of Nainital District, Uttaranchal.

Dental caries is a rapidly emerging oral health problem amongst the children of India. Its incidence in different states varies between 31 and 89%. This study was undertaken with a twin objective of assessing the prevalence of dental caries in parts of Uttaranchal state and designing the interventional strategies with a view to attend the oral health care needs of children. A total of 722 school children in the age range of 7-12 years of Nainital district were examined using WHO (1997) criteria. An overall caries prevalence of 77.7% was recorded, which is 67.26% in the age group of 7-9 years and 80.86% in 10-12 years with DMFT+deft of 1.97 and 2.61, respectively. It was observed that there were greater treatment needs in older age group. Another significant finding of the study was that the 59.96% required restorative treatment out of the various dental treatment needs evaluated.

Albright hereditary osteodystrophy: a rare case report.

Albright hereditary osteodystrophy (AHO) is a rare hereditary metabolic disorder that may be associated with or without resistant to parathyroid hormone (pseudohypoparathyroidism). It is commonly characterized by a constellation of physical features of short stature, round face, short neck, and small metacarpals and metatarsals, mild mental retardation, osteoporosis, subcutaneous calcification, and sometimes olfactory and hearing functional defect. Hypocalcaemia and hyperphosphatemia are the most important manifestations of the case. We report a clinical case of siblings with AHO with reduced Gs-alpha activity and we discuss their clinical features with oral manifestations, radiographic findings, laboratory tests along with treatment.

Microwave synthesized complex concentrated alloy coatings: Plausible solution to cavitation induced erosion-corrosion.

Surface phenomenon such as cavitation erosion-corrosion limits the working life and durability of the fluid machines through significantly altering the efficiency. Surface modification is an apparent and economical route for improving the sustainability of these components. Recently developed complex concentrated alloys (CCAs) or high entropy alloys (HEAs) possess exceptional properties owing to high configurational entropy. We developed CCA coatings on the stainless steel using a facial and effective microwave processing technique. The effect of Al molar fraction in AlxCoCrFeNi (x = 0.1-3) CCAs on ultrasonic cavitation erosion-corrosion was investigated in 3.5% NaCl solution. For comparison, cavitation erosion and electrochemical corrosion behavior of the pre- and post-tested samples was also performed. Detailed microstructure and mechanical characterization of the developed coatings were also preformed using different analytical techniques. The equimolar CCA coating showed apical degradation resistance under both pure erosion and erosion-corrosion conditions. The observed behavior is attributed to high strain hardening, optimal hardness, fracture toughness, and utmost stability of the passive layer. The phenomenal conjugation of these properties was associated with highest configurational entropy for equimolar composition resulting in sluggish diffusion, and severe lattice straining. Compared to pits, striations and cracks characterizing the morphology of the degraded stainless steel, the equimolar and Al0.1CoCrFeNi CCAs showed TTS (tearing topograph surface) as the dominant failure mode characterized by presence of microplastic deformation. The degradation of the Al3CoCrFeNi CCA occurred mainly through brittle failure mode. The difference in failure mechanism is related to the mechanical properties and underlying microstructure.

High Tensile Ductility and Strength in Dual-phase Bimodal Steel through Stationary Friction Stir Processing.

The combination of high strength and good ductility are very desirable for advanced structural and functional applications. However, measures to enhance strength typically lead to ductility reduction due to their inverse correlation, nano-grained structures for an instance. Bi-modal grain structure is promising in this regard, but its realization is limited by multiple complex processing steps. Here, we demonstrate a facile single-step processing route for the development of bimodal grain structure in austenitic stainless steel, SS316L. The bimodal structure comprised of fine martensite grains (<500 nm) sandwiched between coarse austenite grains (~10 µm). The dual-phase bimodal structure demonstrated higher yield strength (~620 MPa) compared to ultra-fine grain structure (~450 MPa) concurrent with high uniform tensile ductility (~35%). These exceptional properties are attributed to unique dual-phase, bimodal grain structure which delayed the onset of plastic instability resulting in higher strength as well as larger uniform elongation and work-hardening rate. Our approach may be easily extended to a wide range of material systems to engineer superior performance.

Dental lamina cyst of newborn: a case report.

Dental lamina cyst, also known as gingival cyst of newborn, is a benign oral mucosal lesion of transient nature. These lesions are usually multiple but do not increase in size. Since the lesions are self-limiting and spontaneously shed a few weeks or months after birth no treatment is required. Clinical diagnoses of these conditions are important in order to avoid unnecessary therapeutic procedure and provide suitable information to parents about the nature of the lesion. In addition, it may be incorrectly diagnosed as natal teeth if present in mandibular anterior region. Here, we present a case of dental lamina cyst of newborn.

Exceptionally high cavitation erosion and corrosion resistance of a high entropy alloy.

Cavitation erosion and corrosion of structural materials are serious concerns for marine and offshore industries. Durability and performance of marine components are severely impaired due to degradation from erosion and corrosion. Utilization of advanced structural materials can play a vital role in limiting such degradation. High entropy alloys (HEAs) are a relatively new class of advanced structural materials with exceptional properties. In the present work, we report on the cavitation erosion behavior of Al0.1CoCrFeNi HEA in two different media: distilled water with and without 3.5wt% NaCl. For comparison, conventionally used stainless steel SS316L was also evaluated in identical test conditions. Despite lower hardness and yield strength, the HEA showed significantly longer incubation period and lower erosion-corrosion rate (nearly 1/4th) compared to SS316L steel. Enhanced erosion resistance of HEA was attributed to its high work-hardening behavior and stable passivation film on the surface. The Al0.1CoCrFeNi HEA showed lower corrosion current density, high pitting resistance and protection potential compared to SS316L steel. Further, HEA showed no evidence of intergranular corrosion likely due to the absence of secondary precipitates. Although, the degradation mechanisms (formation of pits and fatigue cracks) were similar for both the materials, the damage severity was found to be much higher for SS316L steel compared to HEA.

Friction Stir Processing of Stainless Steel for Ascertaining Its Superlative Performance in Bioimplant Applications.

Substrate-cell interactions for a bioimplant are driven by substrate's surface characteristics. In addition, the performance of an implant and resistance to degradation are primarily governed by its surface properties. A bioimplant typically degrades by wear and corrosion in the physiological environment, resulting in metallosis. Surface engineering strategies for limiting degradation of implants and enhancing their performance may reduce or eliminate the need for implant removal surgeries and the associated cost. In the current study, we tailored the surface properties of stainless steel using submerged friction stir processing (FSP), a severe plastic deformation technique. FSP resulted in significant microstructural refinement from 22 µm grain size for the as-received alloy to 0.8 µm grain size for the processed sample with increase in hardness by nearly 1.5 times. The wear and corrosion behavior of the processed alloy was evaluated in simulated body fluid. The processed sample demonstrated remarkable improvement in both wear and corrosion resistance, which is explained by surface strengthening and formation of a highly stable passive layer. The methylthiazol tetrazolium assay demonstrated that the processed sample is better in supporting cell attachment, proliferation with minimal toxicity, and hemolysis. The athrombogenic characteristic of the as-received and processed samples was evaluated by fibrinogen adsorption and platelet adhesion via the enzyme-linked immunosorbent assay and lactate dehydrogenase assay, respectively. The processed sample showed less platelet and fibrinogen adhesion compared with the as-received alloy, signifying its high thromboresistance. The current study suggests friction stir processing to be a versatile toolbox for enhancing the performance and reliability of currently used bioimplant materials.

The role of bio-inspired hierarchical structures in wetting.

Superhydrophobicity facilitates the development of self-cleaning, anti-biofouling, and anti-corrosion surfaces. The leaves of the lotus (Nelumbo nucifera) and taro (Colocasia esculenta) plants are well known for their self-cleaning properties. A hierarchical structure comprising papillae epidermal cells superimposed with epicuticular wax crystalloids of varying shapes, sizes, and orientations is an important aspect of the surface of these plant leaves. We fabricated two types of hierarchical structures biomimicking the surface topography of the lotus leaf. The hierarchical patterns successfully demonstrated the superhydrophobic state in comparison with nano and micro patterns. We used the finite element method (FEM) to simulate and understand the wetting process. The FEM simulations showed good correlation with the experimental results. FEM was helpful in understanding the wetting of enormously complex biological surfaces with relative ease, and it qualifies as a potential tool for designing superhydrophobic surfaces. Using the FEM framework, we further designed surfaces to optimize the order of the shapes in hierarchy. The results showed that the superhydrophobic surface with the lowest wetted area was obtained by placing shapes with smaller geometric angles at the top of the hierarchy. This arrangement of shapes provides the optimum combination of superhydrophobicity and surface integrity. This observation explains why the hierarchical structure of many superhydrophobic leaves follows this order. We also investigated the complex hierarchical structure of Salvinia minima. Owing to its remarkable ability to entrap air and pin the contact line, it exhibits superhydrophobicity along with the much-required Cassie state. These properties of Salvinia minima make it an excellent candidate for developing omniphobic surfaces.

Role of Viscous Dissipative Processes on the Wetting of Textured Surfaces.

We investigate the role of viscous forces on the wetting of hydrophobic, semi-hydrophobic, and hydrophilic textured surfaces as second-order effects. We show that during the initial contact, the transition from inertia- to viscous-dominant regime occurs regardless of their surface topography and chemistry. Furthermore, we demonstrate the effect of viscosity on the apparent contact angle under quasi-static conditions by modulating the ratio of a water/glycerol mixture and show the effect of viscosity, especially on the semi-hydrophobic and hydrophobic textured substrates. The reason why the viscous force does not affect the apparent contact angle of the hydrophilic surface is explained based on the relationship between the disjoining pressure and surface chemistry. We further propose a wetting model that can predict the apparent contact angle of a liquid drop on a textured substrate by incorporating a viscous force component in the force balance equation. This model can predict apparent contact angles on semi-hydrophobic and hydrophobic textured surfaces exhibiting Wenzel state more accurately than the Wenzel model, indicating the importance of viscous forces in determining the apparent contact angle. The modified model can be applied for estimating the wetting properties of arbitrary engineered surfaces.

Region-specific role for GluN2B-containing NMDA receptors in injury to Purkinje cells and CA1 neurons following global cerebral ischemia.

Motor deficits are present in cardiac arrest survivors and injury to cerebellar Purkinje cells (PCs) likely contribute to impairments in motor coordination and post-hypoxic myoclonus. N-Methyl-D-aspartic acid (NMDA) receptor-mediated excitotoxicity is a well-established mechanism of cell death in several brain regions, but the role of NMDA receptors in PC injury remains understudied. Emerging data in cortical and hippocampal neurons indicate that the GluN2A-containing NMDA receptors signal to improve cell survival and GluN2B-containing receptors contribute to neuronal injury. This study compared neuronal injury in the hippocampal CA1 region to that in PCs and investigated the role of NMDA receptors in PC injury in our mouse model of cardiac arrest and cardiopulmonary resuscitation (CA/CPR). Analysis of cell density demonstrated a 24% loss of PCs within 24 h after 8 min CA/CPR and injury stabilized to 33% by 7 days. The subunit promiscuous NMDA receptor antagonist MK-801 protected both CA1 neurons and PCs from ischemic injury following CA/CPR, demonstrating a role for NMDA receptor activation in injury to both brain regions. In contrast, the GluN2B antagonist, Co 101244, had no effect on PC loss while protecting against injury in the CA1 region. These data indicate that ischemic injury to cerebellar PCs progresses via different cell death mechanisms compared to hippocampal CA1 neurons.