Lubricating properties of chewing stimulated whole saliva from patients suffering from xerostomia.

OBJECTIVES: The study aimed to quantify the lubricating properties of chewing stimulated whole saliva from healthy controls (n = 22), from patients suffering from primary Sjögren's syndrome (n = 37) and from patients undergoing head-and-neck radiotherapy (n = 34). MATERIALS AND METHODS: All participants had to complete the Xerostomia Inventory questionnaire to score dry mouth sensation. Lubrication was measured using an ex vivo tongue-enamel friction system in terms of Relief and Relief period. MUC5b and total protein concentrations of the saliva samples were measured by an enzyme-linked immunosorbent assay and a bicinchoninic acid assay, respectively. RESULTS: Relief of Sjögren's patients' saliva and post-irradiation patients' saliva was similar compared with healthy controls, but saliva from post-irradiation patients lubricated significantly better than saliva from Sjögren's patients. The Relief period was similar between the three groups. The Relief and Relief period were higher for saliva samples post-irradiation compared to pre-irradiation. MUC5b and total protein concentrations were comparable in all groups. MUC5b and total protein output were significantly lower in patients subjected to radiotherapy compared to saliva from healthy controls and pre-irradiation patients. MUC5b concentrations positively correlated with lubricating properties of post-irradiation patient saliva. CONCLUSIONS: The lubricating properties of patient saliva were not any worse than healthy controls. Lower flow rate leads to lower availability of saliva in the oral cavity and decreases the overall output of protein and MUC5b, which might result in an insufficient replenishing of the mucosal salivary film. CLINICAL RELEVANCE: An insufficient replenishing might underlie the sensation of a dry mouth and loss of oral function.

Dry mouth: saliva substitutes which adsorb and modify existing salivary condition films improve oral lubrication.

OBJECTIVES: The aims of this study are to assess different saliva substitutes for their efficacy to lubricate the oral cavity, and to relate this oral lubrication to the ability of saliva substitutes to adsorb on and change the structure of the existing salivary conditioning film (SCF). MATERIALS AND METHODS: Quartz crystal microbalance with dissipation was used to study the capability of saliva substitutes to interact with natural SCF and the ability to change the secondary SCF (S-SCF). A tongue-enamel friction system mimicking xerostomic conditions was used to assess the relief and relief period expected from these substitutes under set circumstances. RESULTS: Saliva Orthana spray, Biotène spray and Gum Hydral gel had an immediate effect on a SCF, increasing its structural softness. BioXtra gel, Biotène gel, Gum Hydral gel and Glandosane spray changed the S-SCF by increasing salivary protein adsorption, while others showed no sign of interaction. With respect to relief, only 2 out of the 16 saliva substitutes tested (Saliva Orthana spray and Gum Hydral gel) performed better than water. Overall, relief period correlated positively to structural softness change, whereas a positive correlation was seen between relief and mass adsorption. CONCLUSIONS: The majority of saliva substitutes did not adsorb on the SCF, thus did not enhance lubrication. Only saliva substitutes containing carrageenan, carboxymethylcellulose, pig gastric mucin, xanthan gum and carbomer performed better in enhancing oral lubrication. CLINICAL RELEVANCE: This objective assessment will help clinicians and patients make better choice of saliva substitutes. This study provides a scientific basis for future improvement in saliva substitutes.

Correction to: Dry mouth: saliva substitutes which adsorb and modify existing salivary condition films improve oral lubrication.

After publication of this paper, the authors observed that that figure 6 appears before figure 5.

Changes in lens stiffness due to capsular opacification in accommodative lens refilling.

Accommodation may be restored to presbyopic lenses by refilling the lens capsular bag with a soft polymer. After this accommodative lens refilling prevention of capsular opacification is a requirement, since capsular opacification leads to a decreased clarity of the refilled lens. It has been hypothesized that capsular fibrosis causing the capsular opacification results in increased stiffness of the lens capsular bag, therewith contributing to a decrease in accommodative amplitude of the lens. However, the change in viscoelastic properties of refilled lenses due to capsular fibrosis has never been measured directly. In this study we examined natural lenses from enucleated porcine eyes and refilled lenses directly after refilling and after three months of culturing, when capsular fibrosis had developed, and determined their viscoelastic properties with a low load compression tester. Control refilled lenses were included in which capsular opacification was prevented by treatment with actinomycin D. We related lens stiffening to the degree of capsular opacification, as derived from the microscopic images taken with a confocal laser scanning microscope. Overall, the refilled lenses directly after refilling were softer than refilled lenses after three months of culturing, and refilled lenses treated with actinomycin D were softer compared with untreated refilled lenses. The degree of capsular opacification as assessed by microscopy corresponds to an increase in lens stiffness. This indicates that the viscoelastic properties of the refilled lens are influenced by capsular fibrosis and modulated by treatment of the lens epithelium. In conclusion, this study shows that the development of capsular fibrosis negatively affects the viscoelastic properties of isolated, cultured refilled lenses.

Visualization of microbiological processes underlying stress relaxation in Pseudomonas aeruginosa biofilms.

Bacterial biofilms relieve themselves from external stresses through internal rearrangement, as mathematically modeled in many studies, but never microscopically visualized for their underlying microbiological processes. The aim of this study was to visualize rearrangement processes occurring in mechanically deformed biofilms using confocal-laser-scanning-microscopy after SYTO9 (green-fluorescent) and calcofluor-white (blue-fluorescent) staining to visualize bacteria and extracellular-polymeric matrix substances, respectively. We apply 20% uniaxial deformation to Pseudomonas aeruginosa biofilms and fix deformed biofilms prior to staining, after allowing different time-periods for relaxation. Two isogenic P. aeruginosa strains with different abilities to produce extracellular polymeric substances (EPS) were used. By confocal-laser-scanning-microscopy all biofilms showed intensity distributions for fluorescence from which rearrangement of EPS and bacteria in deformed biofilms were derived. For the P. aeruginosa strain producing EPS, bacteria could not find new, stable positions within 100 s after deformation, while EPS moved toward deeper layers within 20 s. Bacterial rearrangement was not seen in P. aeruginosa biofilms deficient in production of EPS. Thus, EPS is required to stimulate bacterial rearrangement in mechanically deformed biofilms within the time-scale of our experiments, and the mere presence of water is insufficient to induce bacterial movement, likely due to its looser association with the bacteria.

Boundary lubrication by brushed salivary conditioning films and their degree of glycosylation.

OBJECTIVES: Toothbrushing, though aimed at biofilm removal, also affects the lubricative function of adsorbed salivary conditioning films (SCFs). Different modes of brushing (manual, powered, rotary-oscillatory or sonically driven) influence the SCF in different ways. Our objectives were to compare boundary lubrication of SCFs after different modes of brushing and to explain their lubrication on the basis of their roughness, dehydrated layer thickness, and degree of glycosylation. A pilot study was performed to relate in vitro lubrication with mouthfeel in human volunteers. MATERIALS AND METHODS: Coefficient of friction (COF) on 16-h-old SCFs after manual, rotary-oscillatory, and sonically driven brushing was measured using colloidal probe atomic force microscopy (AFM). AFM was also used to assess the roughness of SCFs prior to and after brushing. Dehydrated layer thicknesses and glycosylation of the SCFs were determined using X-ray photoelectron spectroscopy. Mouthfeel after manual and both modes of powered brushing were evaluated employing a split-mouth design. RESULTS: Compared with unbrushed and manually or sonically driven brushed SCFs, powered rotary-oscillatory brushing leads to deglycosylation of the SCF, loss of thickness, and a rougher film. Concurrently, the COF of a powered rotary-oscillatory brushed SCF increased. Volunteers reported a slightly preferred mouthfeel after sonic brushing as compared to powered rotating-oscillating brushing. CONCLUSION: Deglycosylation and roughness increase the COF on SCFs. CLINICAL RELEVANCE: Powered rotary-oscillatory brushing can deglycosylate a SCF, leading to a rougher film surface as compared with manual and sonic brushing, decreasing the lubricative function of the SCF. This is consistent with clinical mouthfeel evaluation after different modes of brushing.

Lectin-Functionalized Polyethylene Glycol for Relief of Mucosal Dryness.

The importance of lubrication between oral surfaces provided by the salivary film is most acutely apparent when it is disrupted, a prevalent consequence of salivary gland hypofunction experienced with aging, a symptom of certain diseases, or a side effect of some medical interventions. Sufferers report difficulty with speech and oral food processing and collectively is detrimental to quality of life. Polyethylene glycol (PEG) is widely employed as a successful biocompatible boundary lubricant in engineering and biomedical applications. It is hypothesized that the immobilization of PEG to biological materials such as oral epithelial cells and tissue can mimic the salivary film and provide durable relief from the symptoms of mucosal dryness. To do so, PEG is functionalized with a sugar binding lectin (wheat germ agglutinin) to enhance epithelial adhesion through lectin-sugar interactions. Retention and lubricity are characterized on an ex vivo oral tissue tribology rig. WGA-PEG coats and retains on mucin films, oral epithelial cells, and porcine tongue tissue, and offers sustained reduction in coefficient of friction (COF). WGA-PEG could be developed into a useful topical treatment for reducing oral friction and the perception of dry mouth.

Influence of fluoride-detergent combinations on the visco-elasticity of adsorbed salivary protein films.

The visco-elasticity of salivary-protein films is related to mouthfeel, lubrication, biofilm formation, and protection against erosion and is influenced by the adsorption of toothpaste components. The thickness and the visco-elasticity of hydrated films (determined using a quartz crystal microbalance) of 2-h-old in vitro-adsorbed salivary-protein films were 43.5 nm and 9.4 MHz, respectively, whereas the dehydrated thickness, measured using X-ray photoelectron spectroscopy, was 2.4 nm. Treatment with toothpaste slurries decreased the thickness of the film, depending on the fluoride-detergent combination involved. Secondary exposure to saliva resulted in a regained thickness of the film to a level similar to its original thickness; however, no association was found between the thickness of hydrated and dehydrated films, indicating differences in film structure. Treatment with stannous fluoride/sodium lauryl sulphate (SnF(2)/SLS)-containing toothpaste slurries yielded a strong, immediate two-fold increase in characteristic film frequency (f(c)) with respect to untreated films, indicating cross-linking in adsorbed salivary-protein films by Sn(2+) that was absent when SLS was replaced with sodium hexametaphosphate (NaHMP). Secondary exposure to saliva of films treated with SnF(2) caused a strong, six-fold increase in f(c) compared with primary salivary-protein films, regardless of whether SLS or NaHMP was the detergent. This suggests that ionized stannous is not directly available for cross-linking in combination with highly negatively charged NaHMP, but becomes slowly available after initial treatment to cause cross-linking during secondary exposure to saliva.

Cartilage lamina splendens inspired nanostructured coating for biomaterial lubrication.

Biomaterials that are used in biological systems, such as polycarbonate urethane (PCU) knee joint implants and contact lenses, generally lack lubrication. This limits their integration with the body and impedes their function. Here, we propose a nanostructured film based on hydrophilic polysaccharide hyaluronic acid conjugated with dopamine (HADN) and zwitterionic reduced glutathione (Glu), which forms a composite coating (HADN-Glu) to enhance the lubrication between cartilage and PCU. HADN was synthesized by carbodiimide chemistry between hyaluronic acid and dopamine and deposited on PCU surface under mild oxidative conditions. Then, zwitterionic peptide-reduced glutathione was bioconjugated to HADN, forming a lubrication film. Analysis based on X-ray photoelectron spectroscopy (XPS), atomic force microscopy (AFM) and wettability indicated that HADN and Glu had grafted successfully onto the PCU surface. Measurements of the coefficient of friction (COF), friction energy dissipation and cartilage roughness indicated that cartilage was effectively protected by the high lubrication of HADN-Glu. Both at low and high applied loads, this effect was likely due to the enhanced boundary lubrication enabled by HADN-Glu on the PCU surface. Moreover, HADN-Glu is highly biocompatible with chondrocyte cells, suggesting that this film will benefit the design of implants where lubrication is needed.

I.2. Mechanics of materials.

Mechanics of materials is the science of forces applied on a body and response of the body in terms of deformation. Different type of loadings on bodies with different geometries or made of different material give rise to different deformations. Last but not the least, this science allows to predict the failure of a body under certain loading condition hence makes it possible to optimize the design for that particular condition.

Next Generation Salivary Lubrication Enhancer Derived from Recombinant Supercharged Polypeptides for Xerostomia.

Insufficient retention of water in adsorbed salivary conditioning films (SCFs) because of altered saliva secretion can lead to oral dryness (xerostomia). Patients with xerostomia sometimes are given artificial saliva, which often lacks efficacy because of the presence of exogenous molecules with limited lubrication properties. Recombinant supercharged polypeptides (SUPs) improve salivary lubrication by enhancing the functionality of endogenously available salivary proteins, which is in stark contrast to administration of exogenous lubrication enhancers. This novel approach is based on establishing a layered architecture enabled by electrostatic bond formation to stabilize and produce robust SCFs in vitro. Here, we first determined the optimal molecular weight of SUPs to achieve the best lubrication performance employing biophysical and in vitro friction measurements. Next, in an ex vivo tongue-enamel friction system, stimulated whole saliva from patients with Sjögren syndrome was tested to transfer this strategy to a preclinical situation. Out of a library of genetically engineered cationic polypeptides, the variant SUP K108cys that contains 108 positive charges and two cysteine residues at each terminus was identified as the best SUP to restore oral lubrication. Employing this SUP, the duration of lubrication (Relief Period) for SCFs from healthy and patient saliva was significantly extended. For patient saliva, the lubrication duration was increased from 3.8 to 21 min with SUP K108cys treatment. Investigation of the tribochemical mechanism revealed that lubrication enhancement is because of the electrostatic stabilization of SCFs and mucin recruitment, which is accompanied by strong water fixation and reduced water evaporation.

Tribological properties of microporous polydimethylsiloxane (PDMS) surfaces under physiological conditions.

Textured biomaterials have been extensively used in biomedical engineering to modulate mammalian and bacterial cell adhesion and proliferation, implant integration with human body and infection prevention. However, the tribological implications of texturing under wet physiological conditions have not been well quantified. This study aimed to characterize the tribological properties of micropore-textured polydimethylsiloxane (PDMS) under physiological conditions and investigate the effect of adsorbed lubricious molecules on friction. In this study, untextured and micropore-textured PDMS surfaces were slid against curved smooth glass surfaces under the contact pressures of 10-400 kPa, sliding speeds of 0.1-5 mm/s in aqueous solutions with the viscosity of 1-1000 mPa·s. Reconstituted human whole saliva (RHWS) at pH 7 and porcine gastric mucin (PGM) at both pH 2 and 7 were used as lubricious coatings on PDMS. While the micropore-texturing delayed the transition of lubrication regimes, it increased the coefficient of friction (COF). Although RHWS and PGM coatings decreased the COF significantly, the protein coatings could not help the COF of micropore-textured surfaces getting lower than that of untextured surfaces. The results suggest textured polymeric surfaces could generate larger friction under physiological conditions and lead to a higher chance of inflammation near the implants.

Bioactive Silk Coatings Reduce the Adhesion of Staphylococcus aureus while Supporting Growth of Osteoblast-like Cells.

Orthopedic and dental implants are associated with a substantial risk of failure due to biomaterial-associated infections and poor osseointegration. To prevent such outcomes, a coating can be applied on the implant to ideally both reduce the risk of bacterial adhesion and support establishment of osteoblasts. We present a strategy to construct dual-functional silk coatings with such properties. Silk coatings were made from a recombinant partial spider silk protein either alone (silkwt) or fused with a cell-binding motif derived from fibronectin (FN-silk). The biofilm-dispersal enzyme Dispersin B (DspB) and two peptidoglycan degrading endolysins, PlySs2 and SAL-1, were produced recombinantly. A sortase recognition tag (SrtTag) was included to allow site-specific conjugation of each enzyme onto silkwt and FN-silk coatings using an engineered variant of the transpeptidase Sortase A (SrtA*). To evaluate bacterial adhesion on the samples, Staphylococcus aureus was incubated on the coatings and subsequently subjected to live/dead staining. Fluorescence microscopy revealed a reduced number of bacteria on all silk coatings containing enzymes. Moreover, the bacteria were mobile to a higher degree, indicating a negative influence on the bacterial adhesion. The capability to support mammalian cell interactions was assessed by cultivation of the osteosarcoma cell line U-2 OS on dual-functional surfaces, prepared by conjugating the enzymes onto FN-silk coatings. U-2 OS cells could adhere to silk coatings with enzymes and showed high spreading and viability, demonstrating good cell compatibility.

Characterization of the in vitro, ex vivo, and in vivo Efficacy of the Antimicrobial Peptide DPK-060 Used for Topical Treatment.

Antimicrobial peptides, also known as host defense peptides, have recently emerged as a promising new category of therapeutic agents for the treatment of infectious diseases. This study evaluated the preclinical in vitro, ex vivo, and in vivo antimicrobial activity, as well as the potential to cause skin irritation, of human kininogen-derived antimicrobial peptide DPK-060 in different formulations designed for topical delivery. We found that DPK-060 formulated in acetate buffer or poloxamer gel caused a marked reduction of bacterial counts of Staphylococcus aureus in vitro (minimum microbicidal concentration <5 µg/ml). We also found that DPK-060 in poloxamer gel significantly suppressed microbial survival in an ex vivo wound infection model using pig skin and in an in vivo mouse model of surgical site infection (≥99 or ≥94% reduction in bacterial counts was achieved with 1% DPK-060 at 4 h post-treatment, respectively). Encapsulation of DPK-060 in different types of lipid nanocapsules or cubosomes did not improve the bactericidal potential of the peptide under the applied test conditions. No reduction in cell viability was observed in response to administration of DPK-060 in any of the formulations tested. In conclusion, the present study confirms that DPK-060 has the potential to be an effective and safe drug candidate for the topical treatment of microbial infections; however, adsorption of the peptide to nanocarriers failed to show any additional benefits.

An ex vivo salivary lubrication system to mimic xerostomic conditions and to predict the lubricating properties of xerostomia relieving agents.

Advances in medical research has resulted in successful treatment of many life-threatening infectious diseases as well as autoimmune and lifestyle-related diseases, increasing life-expectancy of both the developed and developing world. As a result of a growing ageing population, the focus has also turned on chronic diseases which seriously affect the quality of older patient life. Xerostomia (dry mouth) is one such condition, which leads to bad oral health and difficulty in consumption of dry foods and speech. Saliva substitutes are used to ease symptoms. However, they often don't work properly and objective comparison of saliva substitutes to mimic natural salivary functions does not exist. The study thus aims to develop an ex vivo friction assay simulating dry mouth conditions and facilitating objective comparison of saliva substitutes. A reciprocating sliding tongue-enamel system was developed and compared to a PDMS (polydimethylsiloxane)-PDMS friction system. The tongue-enamel system, but not the PDMS-PDMS model, showed high mucin-containing saliva (unstimulated and submandibular/sublingual saliva) to give higher Relief than mucin-poor lubricants (water, parotid saliva, Dentaid Xeros) and correlated well (r = 0.97) with in vivo mouth feel. The tongue-enamel friction system mimicked dry mouth conditions and relief and seems suited to test agents meant to lubricate desiccated oral surfaces.

Introduction of selectivity and specificity to graphene using an inimitable combination of molecular imprinting and nanotechnology.

Recently, the nanostructured modified molecularly imprinting polymer has created a great attention in research field due to its excellent properties such as high surface to volume ratio, low cost, and easy preparation/handling. Among the nanostructured materials, the carbonaceous material such as 'graphene' has attracted the tremendous attention of researchers owing to their fascinating electrical, thermal and physical properties. In this review article, we have tried to explore as well as compile the role of graphene-based nanomaterials in the fabrication of imprinted polymers. In other words, herein the recent efforts made to introduce selectivity in graphene-based nanomaterials were tried collected together. The major concern of this review article is focused on the sensing devices fabricated via a combination of graphene, graphene@nanoparticles, graphene@carbon nanotubes and molecularly imprinted polymers. Additionally, the combination of graphene and quantum dots was also included to explore the fluorescence properties of zero-band-gap graphene.

Single cell imprinting on the surface of Ag-ZnO bimetallic nanoparticle modified graphene oxide sheets for targeted detection, removal and photothermal killing of E. Coli.

A very cost-effective, fast, sensitive and specific imprinted polymer modified electrochemical sensor for the targeted detection, removal and destruction of Escherichia coli bacteria was developed onto the surface of Ag-ZnO bimetallic nanoparticle and graphene oxide nanocomposite. The nanocomposite played a dual role in this work, as a platform for imprinting of bacteria as well as a participated in their laser-light induced photo killing. In terms of sensing, our proposed sensor can detect E. Coli as few as 10CFUmL-1 and capture 98% of bacterial cells from their very high concentrated solution (105CFUmL-1). Similarly to the quantitative detection, we have also investigated the quantitative destruction of E. Coli and found that 16.0cm2 area of polymer modified glass plate is sufficient enough to kill 105CFUmL-1 in the small time span of 5 minutes. The obtained results suggest that our proposed sensor have potential to serve as a promising candidate for specific and quantitative detection, removal as well as the destruction of a variety of bacterial pathogens.

RETRACTED: Anisotropic (spherical/hexagon/cube) silver nanoparticle embedded magnetic carbon nanosphere as platform for designing of tramadol imprinted polymer.

This article has been retracted: please see Elsevier Policy on Article Withdrawal (https://www.elsevier.com/about/our-business/policies/article-withdrawal). This article has been retracted at the request of the Editor-in-Chief following concerns raised by a reader. The particles shown in Fig. 3F appear to be copies of each other as they share the identical arrangement of the characteristic speckles inside the particles. In addition, the extraordinary similarities observed between the data presented in Fig. 4C and in Fig. 3C in ACS Biomater. Sci. Eng., 2017, 3 (9), pp 2120­2135, 10.1021/acsbiomaterials.7b00089, Fig. 4A in Colloids and Surfaces B: Biointerfaces, Volume 142, 1 June 2016, Pages 248-258 10.1016/j.colsurfb.2016.02.053 and Fig. 1D in Biosensors and Bioelectronics, Volume 73, 15 November 2015, Pages 234-244, 10.1016/j.bios.2015.06.005 are highly unlikely. The problems with the data presented cast doubt on all the data, and accordingly also the conclusions based on that data, in this publication. As such this article represents a severe abuse of the scientific publishing system. The scientific community takes a very strong view on this matter and apologies are offered to readers of the journal that this was not detected during the submission process.

An in vitro study of cartilage-meniscus tribology to understand the changes caused by a meniscus implant.

Active lifestyles increase the risk of meniscal injury. A permanent meniscus implant of polycarbonate urethane (PCU) is a promising treatment to postpone/prevent total knee arthroplasty. Study of the changes in articular cartilage tribology in the presence of PCU is essential in developing the optimum meniscus implant. Therefore, a cartilage-meniscus reciprocating, sliding model was developed in vitro, mimicking the stance and swing phases of the gait cycle. The meniscus was further replaced with PCU and surface-modified PCUs (with C18 chains, mono-functional polydimethylsiloxane groups and mono-functional polytetrafluoroethylene groups) to study the changes. The coefficient of friction (COF) was calculated, and cartilage wear was determined and quantified histologically. The cartilage-meniscus sliding resulted in low COF during both stance and swing (0.01< COF <0.12) and low wear of cartilage (scores <1). The cartilage-PCU sliding, during stance, revealed similar low COFs. But during swing, the COFs were high (average ∼1, maximum 1.6), indicating a breakdown in interstitial fluid pressurization lubrication and non-effective activation of the boundary lubrication. This may lead to wear of cartilage in long term. However, under the tested conditions the wear of cartilage against PCUs was not higher than its wear against meniscus, and the cartilage was occasionally damaged. The COF decreased with increasing the contact pressure (as-per a power equation) up to 1MPa. The changes in the surface modification of PCU did not affect PCU's tribological performance.

RETRACTED: Graphene quantum dots decorated CdS doped graphene oxide sheets in dual action mode: As initiator and platform for designing of nimesulide imprinted polymer.

This article has been retracted: please see Elsevier Policy on Article Withdrawal (https://www.elsevier.com/about/our-business/policies/article-withdrawal). This article has been retracted at the request of Editor following concerns raised by a reader. The article uses several electron micrographs which have been used in other publications as well denoting different samples. Fig. 2A was reused from Fig. 3A, Chemical Engineering Journal, Volume 299, 1 September 2016, Pages 244-254, 10.1016/j.cej.2016.04.051. According to the authors this was due to a mistake at the compilation of the manuscript (mixing images from the GO and Cds:GO samples). Fig. 2C was reused (a lower zoom level) from Fig. 1F, Biosensors and Bioelectronics, Volume 89, Part 1, 15 March 2017, Pages 620-626, 10.1016/j.bios.2015.12.085. The inset in Fig. 1F was reused from Fig. 2D, Environ. Sci. Technol., 2015, 49 (10), pp 6117­6126, 10.1021/acs.est.5b00182. These problems with the data presented cast doubt on all the data, and accordingly also the conclusions based on that data, in this publication. As such this article represents a severe abuse of the scientific publishing system. The scientific community takes a very strong view on this matter and apologies are offered to readers of the journal that this was not detected during the submission process.