Influence of the second phase on protein adsorption on biodegradable Mg alloys' surfaces: Comparative experimental and molecular dynamics simulation studies

The effect of the second phase on the mechanical properties and corrosion resistance of Mg alloys has been systematically studied. However, there is limited information on the effect of the second phase on protein adsorption behavior. In the present study, the effect of the second phase on protein adsorption on the surfaces of biodegradable Mg alloys was investigated using experimental methods and molecular dynamics (MD) simulations. The experimental results showed that the effect of the second phase on fibrinogen adsorption was type-dependent. Fibrinogen preferentially adsorbed on Y-, Ce-, or Nd-involved second phases, while the second phase containing Zn inhibited its adsorption. MD simulations revealed the mechanism of the second phase that influenced protein adsorption in terms of charge distribution, surface-protein interaction energy, and water molecule distribution. Our studies proposed a deep understanding of the design of Mg-based biomaterials with superior biocompatibility. STATEMENT OF SIGNIFICANCE: Mechanical properties, uniform degradation, and biocompatibility must be considered while designing biomedical Mg alloys. To improve the mechanical properties and corrosion resistance of Mg alloys, the second phase is usually required. However, the effects of the second phase on biocompatibility of Mg alloys have been rarely reported. Here, the influence of the second phase on protein adsorption was experimentally studied by designing Mg alloys with different types of second phase. The first principle calculation and MD simulation were used to reveal the mechanism by which the second phase influences protein adsorption. This work could be used to better elucidate the protein adsorption mechanisms and design principles to improve the biocompatibility of Mg alloys.

The viability of SARS-CoV-2 on solid surfaces

The COVID-19 pandemic had a major impact on life in 2020 and 2021. One method of transmission occurs when the causative virus, SARS-CoV-2, contaminates solids. Understanding and controlling the interaction with solids is thus potentially important for limiting the spread of the disease. We review work that describes the prevalence of the virus on common objects, the longevity of the virus on solids, and surface coatings that are designed to inactivate the virus. Engineered coatings have already succeeded in producing a large reduction in viral infectivity from surfaces. We also review work describing inactivation on facemasks and clothing and discuss probable mechanisms of inactivation of the virus at surfaces.

Diurnal variation in the human skin microbiome affects accuracy of forensic microbiome matching

BACKGROUND

The human skin microbiome has been recently investigated as a potential forensic tool, as people leave traces of their potentially unique microbiomes on objects and surfaces with which they interact. In this metagenomic study of four people in Hong Kong, their homes, and public surfaces in their neighbourhoods, we investigated the stability and identifiability of these microbiota traces on a timescale of hours to days.

RESULTS

Using a Canberra distance-based method of comparing skin and surface microbiomes, we found that a person could be accurately matched to their household in 84% of tests and to their neighbourhood in 50% of tests, and that matching accuracy did not decay for household surfaces over the 10-day study period, although it did for public surfaces. The time of day at which a skin or surface sample was taken affected matching accuracy, and 160 species across all sites were found to have a significant variation in abundance between morning and evening samples. We hypothesised that daily routines drive a rhythm of daytime dispersal from the pooled public surface microbiome followed by normalisation of a person's microbiome by contact with their household microbial reservoir, and Dynamic Bayesian Networks (DBNs) supported dispersal from public surfaces to skin as the major dispersal route among all sites studied.

CONCLUSIONS

These results suggest that in addition to considering the decay of microbiota traces with time, diurnal patterns in microbiome exposure that contribute to the human skin microbiome assemblage must also be considered in developing this as a potential forensic method. Video Abstract.

Evaluating quality of soils formed on basement complex rocks in Kaduna State, northern Guinea savanna of Nigeria

A few investigations have been done regarding the soil quality index (SQI) for various locations, soil types, and states. Still, little has been reported regarding SQI for both surface and control sections, especially for the Northern Guinea Savanna of Nigeria. Due to the subsurface property pedogenic influence on soil function, it is crucial to assess SQI using surface and subsurface properties as both properties influence soil productivity. We investigated the potentials of choosing a minimum data set for soil quality indicators and assess soil quality (SQ), using both surface and entire soil pedon data for the soils on the basement complexes. Both additive and weighted soil quality indices and different scoring methods (linear and non-linear) were used in evaluating SQ. Out of the twenty-three soil properties subjected to PCA, eight indicators (TEB, clay, silt, K, EA, EC, BD, and Fe) were selected as the minimum data set (MDS). There was not much difference in the calculated soil quality using the non-linear additive (SQI-NLA), linear additive (SQI-LA), linear weighted (SQI-LW), and non-linear weighted (SQI-NLW) for the soils as they were all rated low (SQI < 0.55). The estimated SQI for the control section had relatively higher values than the surface soil, thus suggesting the need to incorporate both surface and entire soil profile properties in assessing SQ as both are important in integrating the relationship between soil properties and management goals which eventually provides complete information that affects the production of crops.

Efficient development of silk fibroin membranes on liquid surface for potential use in biomedical materials

Silk fibroin (SF) protein is versatile for the application of biomaterials due to its excellent mechanical properties, biocompatibility and biodegradability. However, the efficient way to fabricate SF membranes with special structure is still challenging. Here, we develop an efficient and simple way to create SF membranes on the liquid (i.e. subphase) surface. It is essential to prepare highly concentrated SF solution with low surface tension by dissolving the degummed SF powders in 6% (w/v) LiBr/methanol solution by one step. 95 wt% polyethylene glycol (PEG) 200 and 30 wt% (NH₄)₂SO₄ are the subphases, on which the SF solution spreads quickly, generating nonporous and microporous SF membranes (SFM-1 and SFM-2), respectively. PEG 200 causes more ordered molecular packing (β-sheets) in SFM-1. While Fast diffusion and denaturation of SF on (NH₄)₂SO₄ solution lead to the formation of microporous, water-unstable membrane SFM-2. Both membranes have good transparency, hydrophilicty, and mechanical properties. To fabricate antibacterial biomaterials, we design a composite membrane by SFM-1 and SFM-2 sandwiching a layer of hydroxypropyl trimethylammonium chloride chitosan (HACC) to provide antibacterial functions. The sandwich membrane has good cell viability and antibacterial properties, showing potential use for biomedical materials.

Multifunctional superhydrophobic surfaces

Surface wetting has a significant influence on the performance and applications of the materials. The superhydrophobic surfaces have water repellency due to low surface energy chemistry and micro/nanostructure roughness. The amazing applications of superhydrophobic surfaces (SHSs) lead to increase attention to superhydrophobicity in recent decades. The SHSs have been fabricated through chemical and physical methods. The further properties of SHSs as functions such as self-healing, anti-bacterial, anti-fouling, and stimuli-responsiveness are considered as the functions of the SHSs. The Multifunctional SHSs (MSHSs) that contained superhydrophobicity and at least two other properties as the next generation of the SHSs are swiftly developed in recent years. The multiple applications of the MSHSs are originated from specific morphology and functional groups of the MSHSs. The functions (properties) of the MSHSs are categorized into three groups including self-cleaning properties, restrictive properties, and smart properties. Designing and keeping surface structure plays a significant role in fabricating durable MSHSs. However, there is a big challenge to design and also scale up mechanochemical durable MSHSs. Based on state-of-the-art investigations, establishing a self-healing function can improve the durability of SHSs. The durable self-healing MSHSs can enhance the performance of the other functions and lifespan of the surface. In this review, all surface structures and superhydrophobic agents in MSHSs are investigated. The perspective of the MSHSs determined the next generation of the MSHSs have several significant parameters including durability, stability, more functions, more responsiveness, and environmentally friendly features for fabricating the large-scale MSHSs and enhancing their applications.

The salivary pellicle on dental biomaterials

The salivary pellicle, an adlayer formed by adsorption of salivary components on teeth and dental biomaterials, has direct consequences on basic outcomes of dentistry. Here, we provide an overview of salivary pellicle formation processes with a critical focus on dental biomaterials. We describe and critique the array of salivary pellicle measurement techniques. We also discuss factors that may affect salivary pellicle formation and the heterogeneity of the published literature describing salivary pellicle formation on dental biomaterials. Finally, we survey the many effects salivary pellicles have on dental biomaterials and highlight its implications on design criteria for dental biomaterials. Future investigations may lead to rationally designed dental biomaterials to control the salivary pellicle and enhance material function and patient outcomes.

Rapid inactivation of SARS-CoV-2 by titanium dioxide surface coating

Background: Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) transmission occurs via airborne droplets and surface contamination. Titanium dioxide (TiO 2) coating of surfaces is a promising infection control measure, though to date has not been tested against SARS-CoV-2. Methods: Virus stability was evaluated on TiO 2- and TiO 2-Ag (Ti:Ag atomic ratio 1:0.04)-coated 45 x 45 mm ceramic tiles. After coating the tiles were stored for 2-4 months before use. We tested the stability of both SARS-CoV-2 Spike pseudotyped virions based on a lentiviral system, as well as fully infectious SARS-CoV-2 virus. For the former, tile surfaces were inoculated with SARS-CoV-2 spike pseudotyped HIV-1 luciferase virus. At intervals virus was recovered from surfaces and target cells infected. For live virus,  after illuminating tiles for 0-300 min virus was recovered from surfaces followed by infection of Vero E6 cells. % of infected cells was determined by flow cytometry detecting SARS-CoV-2 nucleocapsid protein 24 h post-infection. Results: After 1 h illumination the pseudotyped viral titre was decreased by four orders of magnitude. There was no significant difference between the TiO 2 and TiO 2-Ag coatings. Light alone had no significant effect on viral viability. For live SARS-CoV-2, virus was already significantly inactivated on the TiO 2 surfaces after 20 min illumination. After 5 h no detectable active virus remained. Significantly, SARS-CoV-2 on the untreated surface was still fully infectious at 5 h post-addition of virus. Overall, tiles coated with TiO 2 120 days previously were able to inactivate SARS-CoV-2 under ambient indoor lighting with 87% reduction in titres at 1h and complete loss by 5h exposure. Conclusions: In the context of emerging viral variants with increased transmissibility, TiO 2 coatings could be an important tool in containing SARS-CoV-2, particularly in health care facilities where nosocomial infection rates are high.

Highly hydrophobic polytetrafluoroethylene particle immobilization via polydopamine anchor layer on nitric oxide releasing polymer for biomedical applications

Biomedical surface-associated infections and thrombus formation are two major clinical issues that challenge patient safety and patient the fate of a medical device in the body . Single platform multifunctional surfaces are critical to address both these indwelling medical device-related problems. In this work, bio-inspired approaches are employed to fabricate a polymer composite with a versatile surface that can reduce bacterial infections and platelet adhesion in vitro. In the first bio-inspired approach, the functionality of nitric oxide (NO) produced by endothelial cell lining of blood vessels is mimicked through incorporation of S-nitroso-N-acetylpenicillamine (SNAP) within a CarboSil-2080A™ (CarboSil) polymer composite matrix. The second approach involves utilizing mussel adhesive chemistry, via polydopamine (PDA) to immobilize polytetrafluoroethylene (PTFE) particles on the polymer composite surface. The PTFE coating facilitates a decrease in wettability by making the polymer composite surface highly hydrophobic (contact angle ca. 120°). The surface of the fabricated polymer composite , CarboSil SNAP-PTFE, had a cobblestone-like structured appearance as characterized through scanning electron microscopy (SEM). Water contact angle (WCA) and surface tension measurements indicated no significant coating losses after 24 h under physiological conditions. NO surface flux was measured and analyzed for 5 days using a chemiluminescence-based nitric oxide analyzer and was found to be within the physiological range. CarboSil SNAP-PTFE reduced adhered bacteria (99.3 ± 0.5% for Gram-positive S. aureus and 99.1 ± 0.4% for Gram-negative E. coli) in a 24 h in vitro study. SEM analysis showed the absence of biofilm formation on CarboSil SNAP-PTFE polymer composites, while present on CarboSil in 24 h exposure to S. aureus. Platelet adhesion was reduced by 83.3 ± 4.5%. Overall, the results of this study suggest that a combination of NO-releasing CarboSil with PTFE coating can drastically reduce infection and platelet adhesion.

Surface roughness of enamel and root surface after scaling, root planning and polishing procedures: An in-vitro study

Objectives

The aim of this study was to evaluate enamel and root surface roughness on exracted human teeth by using different tecniques (ultrasonic scaler, hand instruments, polishing paste, pumice and air powder system).

Materials and methods

A total of 200 samples were divided into two groups (enamel and root) randomly with 100 samples for each enamel and root groups. The groups were divided into 5 subgroups: Group I: ultrasonic scaler, group II: hand instruments, group III: polishing paste, group IV: pumice, group V: air-powder. Surface roughness (Ra) was assessed with Mitutoyo SJ-410 device. The one-way analysis of variance (ANOVA) test along with the Tukey test was used for statistical analysis. P values less than 0.05 were considered statistically significant.

Results

The use of ultrasonic scalers caused the highest roughness increase on the enamel surface (0.935 ​± ​0.010), whereas the use of pumice was the least (0.896 ​± ​0.018) (p ​< ​0.05). There was a significant difference between ultrasonic scalers and all the groups (hand instruments, polishing paste, pumice and air powder system) on enamel surface (p ​< ​0.05). Maximum surface roughness increase was observed in the ultrasonic scalers on root surface. There was a significant difference between ultrasonic scalers and polishing paste, pumice and air powder on root surface, respectively (p ​< ​0.05).

Conclusion

The use of ultrasonic scalers cause more rough enamel and root surfaces than hand instrumentation and polishing tecniques.

Clinical relevance

Uneven surfaces adversely affect the intended periodontal healing by creating a retention area of microbial dental plaque.

A PCR method to identify ochratoxin A-producing Aspergillus westerdijkiae strains on dried and aged foods

Ochratoxins are a group of mycotoxins that frequently occur as contaminants in agricultural commodities and foods, including dry-cured meats and cheeses. The fungus Aspergillus westerdijkiae is frequently isolated from aged foods and can produce ochratoxin A (OTA). However, individual strains of the fungus can have one of two OTA production phenotypes (chemotypes): OTA production and OTA nonproduction. Monitoring and early detection of OTA-producing fungi in food are the most effective strategies to manage OTA contamination. Therefore, we examined genome sequence data from five A. westerdijkiae strains isolated from the surface of cheese from southern Italy to identify genetic markers indicative of the twoOTA chemotypes. This analysis revealed a naturally occurring deletion of the OTA regulatory gene, otaR, in an OTA-nonproducing isolate.We used this information to design a polymerase chain reaction (PCR) method that could identify A. westerdijkiae and distinguish between the two OTA chemotypes. In this method, the PCR primers were complementary to conserved sequences flanking otaR and yielded different-sized amplicons from strains with the different chemotypes. The primers did not yield ota-region-specific amplicons from other OTA-producing species. Because the method is specific to A. westerdijkiae and can distinguish between the two OTA chemotypes, it has potential to significantly improve OTA monitoring programs.

Why does SARS-CoV-2 survive longer on plastic than on paper?

The Covid-19 coronavirus, SARS-CoV-2, is inactivated much faster on paper (3 h) than on plastic (7 d). By classifying materials according to virus stability on their surface, the following list is obtained (from long to short stability): polypropylene (mask), plastic, glass, stainless steel, pig skin, cardboard, banknote, cotton, wood, paper, tissue, copper. These observations and other studies suggest that SARS-CoV-2 may be inactivated by dryness on water absorbent porous materials but sheltered by long-persisting micro-droplets of water on waterproof surfaces. If such physical phenomenons were confirmed by direct evidence, the persistence of the virus on any surface could be predicted, and new porous objects could be designed to eliminate the virus faster.

Surface-Plasmon Holography

Holography was originally invented for the purpose of magnifying electron microscopic images without spherical aberration and has been applied to photography for recording and reconstructing three-dimensional objects. Although it has been attracting scientists and ordinary people in the world, it is still a technology in science fiction movies. In this review, we discuss a new version of holography that uses surface plasmons on thin metal film. We discuss conventional holography and its drawbacks, such as overlapping of ghost and background due to the contribution of unnecessary diffraction and monochromacy for avoiding the unwanted diffraction components of different colors. Surface-plasmon holography is a version of near-field holography to overcome drawbacks of conventional holography. Comparison with conventional and volume holography for color reconstruction is discussed in reciprocal lattice space. Localized mode of surface plasmons and meta-surface holography are also reviewed, and feature perspectives and issues are discussed.

Detection and infectivity potential of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) environmental contamination in isolation units and quarantine facilities

OBJECTIVES

Environmental surfaces have been suggested as likely contributors in the transmission of COVID-19. This study assessed the infectivity of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) contaminating surfaces and objects in two hospital isolation units and a quarantine hotel.

METHODS

SARS-CoV-2 virus stability and infectivity on non-porous surfaces was tested under controlled laboratory conditions. Surface and air sampling were conducted at two COVID-19 isolation units and in a quarantine hotel. Viral RNA was detected by RT-PCR and infectivity was assessed by VERO E6 CPE test.

RESULTS

In laboratory-controlled conditions, SARS-CoV-2 gradually lost its infectivity completely by day 4 at ambient temperature, and the decay rate of viral viability on surfaces directly correlated with increase in temperature. Viral RNA was detected in 29/55 surface samples (52.7%) and 16/42 surface samples (38%) from the surroundings of symptomatic COVID-19 patients in isolation units of two hospitals and in a quarantine hotel for asymptomatic and very mild COVID-19 patients. None of the surface and air samples from the three sites (0/97) were found to contain infectious titres of SARS-Cov-2 on tissue culture assay.

CONCLUSIONS

Despite prolonged viability of SARS-CoV-2 under laboratory-controlled conditions, uncultivable viral contamination of inanimate surfaces might suggest low feasibility for indirect fomite transmission.

Synthesis and cytotoxic analysis of thiolated xylose derivatives decorated on gold nanoparticles

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Nanoparticles covered with carbohydrates constitute a good bio-mimetic model.

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D-xylose gold nanoparticles with linkages of alkyl or polyethylene glycol synthesized via D-xylosethiols.

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Forming self-assembled monolayers on gold nanoparticles.

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The potential use of intact or thiolated xylose derivatives decorated on AuNPs.

The rapid development of metal nanoparticles capped by an organic monolayer offers the possibility to create a whole new variety of products with novel characteristic, functions and applications. Among these, nanoparticles covered with carbohydrates (glyconanoparticles) constitute a good bio-mimetic model of carbohydrate presentation at the cell surface and are currently centered on many glycobiological and biomedical applications. In this study, a series of novel D-xylose gold nanoparticles (AuNPs) with linkages of alkyl or polyethylene glycol have been synthesized via D-xylosethiols, forming self-assembled monolayers on gold nanoparticles. The nano-gold solution, two carbohydrate derivatives and modified nano-gold solution were tested for cytotoxicity to check the biocompatibility. The MTT assay on NIH 3T3 cell lines confirmed that all the test materials showed no toxicity with the more than 90 % of cell viability in both low concentration (1 μM) and high concentration (100 μM), compared with the control.

Jockey Perception of Shoe and Surface Effects on Hoof-Ground Interactions and Implications for Safety in the Galloping Thoroughbred Racehorse

Riding racehorses is a high-risk profession and optimizing safety alongside performance is paramount. Horseshoes play a critical role in providing traction with the ground surface and are therefore a major determinant of safety. However, the subjective perceptions of expert riders influence attitudes towards using different shoes and must be taken into consideration before any changes may be implemented. This study used a questionnaire-based method to evaluate jockey opinion of four shoeing conditions (aluminum, steel, GluShu, and barefoot) trialed at gallop over turf and artificial surfaces. Nine Lickert-style questions explored impact, cushioning, responsiveness, grip, uniformity, smoothness of ride, safety, adaptation period, and overall rating for each shoe-surface combination. A total of 94 questionnaires, based on 15 horse-rider pairs, were assessed using descriptive statistics and linear mixed models performed in SPSS (P < .05). Data indicate that shoe type significantly affected all question responses, with the exception of impact. Surface-type significantly affected perception of grip and safety. Overall, jockeys showed a preference for aluminum and steel shoes across both artificial and turf tracks. These rated "excellent" and were considered to be "very supportive" in approximately 80% of trials, with a 100% "active" response, good grip, and a quick adaptation period. In contrast, barefoot and GluShu conditions were generally considered "moderately supportive," with barefoot appearing favorable on the artificial surface. On turf, barefoot was deemed the least smooth and the only condition that jockeys sometimes marked "unsafe" (17% of responses). Future work aims to investigate the relationship between jockey opinion and hoof kinematic data.

Effect of amylase activity on mechanical properties of dental composite resin

The purpose of this study was to investigate the effect of amylase activity on the mechanical properties of three dental composite resin (Filtek Z350; Filtek Z250 and Polofil Supra). The specimens were immersed in amylase solution at four different activities (25, 50, 100 and 200 KIU/L) with an artificial saliva solution (AS) as a control. The flexural strength (FS) and elastic modulus (EM) were determined in a three-point bending test after immersion for periods up to 12 months. In addition, surface roughness and surface morphology also determined. The FS of Filtek Z350 reaching the lowest level of 67.86 MPa after AS immersion for one year. There was a general trend for FS to decrease following immersion in AS for all the tested materials. However, the amylase groups did not undergo a significant decrease in FS and EM, and there was a slight increase in FS and EM for Polofil Supra.

Surface mole-ratio method to distinguish surface precipitation and adsorption on solid-liquid interface

The enhancement effects of phosphate (P) on Pb removal by adsorbents have been attributed to co-adsorption of P and Pb, the formation of P-Pb surface ternary surface complexes, and surface precipitation of P and Pb. However, distinguishing adsorption from surface precipitation in multi-adsorbate systems has been a challenge. For the first time, a surface mole-ratio (SMR) method was established and applied for delineating Pb-P precipitation and Pb adsorption on an acrylic amine fiber (AAF) adsorbent. In elaborating the SMR method, we developed Pb removal experiments by mixing solutions containing 0.2 g/L of AAF, 6 and 12 μmol/L P, and 0-35 μmol/L Pb. When the removed Pb/P (μmol/μmol) was plotted as a function of the equilibrium Pb (μmol/L), the SMR diagram exhibited a turning-point similar to the Pb/P mole ratio of 5/3 = 1.67 in pyromorphite (Pb₅(PO₄)₃OH) precipitate. The SMR diagram indicated that when the Pb concentration increased, the precipitate formed first; after all P formed precipitates, Pb was removed by adsorption. The precipitation and adsorption processes were further confirmed by other SMR diagrams, FTIR, SEM-EDX, and XRD analysis. The SMR method will have broad applications in determining the removal mechanisms of multi-adsorbates by adsorbents and coagulants, and stabilization mechanisms of heavy metals in soils. With the development and application of more modern in-situ characterization techniques, SMR method will be more effective.

Physical stability of amorphous pharmaceutical solids: Nucleation, crystal growth, phase separation and effects of the polymers

Compared to their crystalline forms, amorphous pharmaceutical solids present marvelous potential and advantages for effectively improving the oral bioavailability of poorly water-soluble drugs. A central issue in developing amorphous pharmaceutical solids is the stability against crystallization, which is particularly important for maintaining their advantages in solubility and dissolution rate. This review provides a comprehensive overview of recent studies focusing on the physical stability of amorphous pharmaceutical solids affected by nucleation, crystal growth, phase separation and the addition of polymers. Moreover, we highlight the novel technologies and theories in the field of amorphous pharmaceutical solids. Meanwhile, the challenges and strategies in maintaining the physical stability of amorphous pharmaceutical solids are also discussed. With a better understanding of physical stability, the more robust amorphous pharmaceutical formulations with desired pharmaceutical performance would be easier to achieve.

Confocal Laser Microscopy Analysis of Listeria monocytogenes Biofilms and Spatially Organized Communities

The behavior of Listeria monocytogenes communities in the food chain is closely associated with their spatial organization. Whether as biofilms on industrial surfaces or as microcolonies in food matrices, the resulting physiological diversification combined with the presence of extracellular polymeric substances (EPS) triggers emergent community functions involved in the pathogen survival and persistence (e.g., tolerance to dehydration, biocides, or preservatives). In this contribution, we present a noninvasive confocal laser microscopy (CLM) protocol allowing exploration of the spatial organization of L. monocytogenes communities on various inert or nutritive materials relevant for the food industry.

Decontamination efficacy of sodium hypochlorite solutions for poliovirus

Effective decontamination procedures are critical to the successful manufacture and control of poliovirus vaccines to minimize the risk to personnel and the environment. Polio viruses have been reported to be more resistant to disinfectants than many other viruses. We assessed the efficacy of sodium hypochlorite-containing disinfectants for decontamination for three poliovirus serotypes to implement decontamination procedures that are fully compliant with the WHO GAP III and Health authorities' requirements. A 10.4 log reduction was observed with a 0.63% sodium hypochlorite solution in a suspension with high protein and high poliovirus concentrations diluted 10-fold compared with a 6 log reduction in an undiluted sample. Treatment efficacy increased with sodium hypochlorite content and decreased with sample protein content. The surface tests showed that two 1-min treatments, 5-min apart, with a 0.63% Chl sodium hypochlorite solution effectively reduced the concentration of all poliovirus serotypes by 10 log₁₀, irrespective of the protein and virus concentration in the sample. Sodium hypochlorite solutions lower than 0.52% were less effective for complete inactivation of poliovirus. In conclusion, we demonstrated that a high level of virus reduction (>10 log₁₀) can be achieved with sodium hypochlorite solutions with poliovirus in suspension and dried on surfaces.

Do surface electrodes validly represent lower trapezius activation patterns during shoulder tasks?

Because of its superficial location, surface electrodes are commonly used to record lower trapezius activity. Recent evidence, however, would suggest that surface electromyography is not a valid to record activity from other superficially placed shoulder muscles. Therefore, the aim of this study was to determine the validity of using surface electrodes to record lower trapezius activity. Ten asymptomatic subjects performed ramped isometric (0-100% maximum load) and dynamic (70% maximum load) shoulder tasks. Intramuscular electrodes were inserted into lower trapezius and rhomboid major. Surface electrodes were placed over lower trapezius around the intramuscular electrodes. Differences in the recorded activity of lower trapezius between surface and intramuscular electrodes were tested using a 2 factor repeated measures analysis of variance with factors: test and electrode type. Similarity in the recorded activity patterns between the two electrodes was tested using Pearson's correlation coefficient (r). Results indicated that there was no difference in lower trapezius activity levels (p = 0.98) or activation patterns (r ≥ 0.74) recorded by the intramuscular and surface electrodes. The results of this study indicate that any potential crosstalk contamination in the surface electrode signal is having little influence on the recorded activity from lower trapezius and therefore, support the common practice of surface electromyography to investigate lower trapezius function.

Parametric evaluation of electrical discharge coatings on nickel-titanium shape memory alloy in deionized water

Nickel-titanium shape memory alloy (NiTi) has a unique capacity to restore its initial shape after deformation, which is highly applicable to orthopaedic implantations, especially for the minimization of invasive surgeries. The high nickel content of this alloy can lead to unfavourable effects on the human body upon dissolution; thus, a reliable barrier of coatings on the NiTi surface is required to alleviate the nickel migration and increase its biocompatibility. In this paper, analyses of a titanium oxide layer development on NiTi surface using electrical discharge coating (EDC) process is presented. The recast layer thickness, crater sizes, and surface roughness were characterized based on five parameters; polarity, discharge duration, pulse interval, peak current, and gap voltage. The results show that the discharge duration is the most significant parameter to influence all responses, followed by peak current. The surface characteristics of the EDC substrate is depending on the crater formations and is highly correlated with the discharge energy intensity. As a result, appropriate parametric conditions of the electrical discharge coating process can enhance the NiTi surface for future medical applications, without compromising the shape memory effect.

Hepatic surface grooves in Trinidad and Tobago

PURPOSE

Hepatic surface grooves (HSGs) are prominent depressions on the antero-superior surface of the liver. We sought to document the prevalence of HSGs in an Eastern Caribbean population.

METHODS

We observed all consecutive autopsies performed at a facility in Trinidad and Tobago and recorded the presence, number, location, width, length and depth of any HSG identified. Each liver was then sectioned to document intra-parenchymal abnormalities.

RESULTS

Sixty Autopsies were observed. There were HSGs in 9 (15%) cadavers (5 females and 4 males), at an average age of 66 years (range 48-83, Median 64, SD ± 10.4). The HSGs were located on the diaphragmatic surface of the right hemi-liver in 8 (89%) cadavers, left medial section in 4 (44%), left lateral section in 3 (33%) and coursing along Cantlie's plane in 3 (33%) cadavers. Eight (89%) cadavers with HSGs had other associated anomalies: accessory inferior grooves (5), parenchymal nutmeg changes (5), abnormal caudate morphology (4), hyperplastic left hemi-liver (3), lingular process (2), bi-lobar gallbladder (1) and/or abnormal ligamentous attachments (1).

CONCLUSIONS

Approximately 15% of unselected Afro-Caribbean persons in this Eastern Caribbean population have HSGs. Every attempt should be made to identify HSGs on pre-operative imaging because they can alert the hepatobiliary surgeon to: (1) associated anatomic anomalies in 89% of cases, (2) associated hepatic congestion in 56% of persons, (3) increased risk of bleeding during liver resections and (4) increased technical complexity of liver resections. The association between HSGs, cardiovascular complications, hepatic congestion and nutmeg liver prompted us to propose a new aetiologic mechanism for HSG formation, involving localized hyperplasia at growth zones due to upregulation of beta-catenin levels.

Factors affecting aseptic loosening in primary total knee replacements: an in vitro study

Background

Implant surface integrity and cement bonding are assumed to be sufficient in primary total knee replacements to stabilize implants for extended wear without concerns over delamination and loosening. Yet there exists a significant rate of aseptic loosening where failure at implant cement interface occurs. The aim of this study is to look at specific aspects leading to aseptic loosening of the total knee replacement, where cement adhesion to the implant results in the lowest pull off strength.

Methods

Virgin ceramic coated and uncoated chrome cobalt tibial trays were used in a pull off study using differing viscosities of cement at varied time intervals to compare which combination is strongest compared to which is least resistant to pull off testing.

Results

Low viscosity cement had a 44% (5.9 kg verses 3.3 kg, p < 0.001) higher pull-off strength compared to high viscosity cement. Coated implants had a 30% (3.9 kg verses 5.5 kg, p = 0.037) lower pull-off strength compared to non-coated. Testing measures were limited to cement utilization less than 5 minutes due to the poor adhesion of the dowels beyond this time. Finally, there was a significant difference in adhesion properties between brand names when utilizing low viscosity cement on the non-coated trays (10.34 kg for Simplex verses 4.87 for Palacos, p = 0.021).

Conclusion

There are differences in adhesion properties between cement vendors, prompting significant concerns over the use of coated implants with particular cement types. Use of low viscosity cement on non-coated surfaces in the early liquid phase of cement curing was found to produce the best chance for adequate adhesion. This study demonstrates that there is variation in the adhesive properties of implants utilized in total knee replacements, and that the orthopedic community should consider not only the implant, cement, and curing time individually, but the overall integrity conferred from the combination of all of these variables.