Superhydrophobic Paper from Nanostructured Fluorinated Cellulose Esters

The development of economically and ecologically viable strategies for sup erhydrophobization offers a vast variety of interesting applications in self-cleaning surfaces. Examples include packaging materials, textiles, outdoor clothing, and microfluidic devices. In this work, we produced superhydrophobic paper by spin-coating a dispersion of nanostructured fluorinated cellulose esters. Modification of cellulose nanocrystals was accomplished using 2H,2H,3H,3H-perfluorononanoyl chloride and 2H,2H,3H,3H-perfluoroundecanoyl chloride, which are well-known for their ability to reduce surface energy. A stable dispersion of nanospherical fluorinated cellulose ester was obtained by using the nanoprecipitation technique. The hydrophobized fluorinated cellulose esters were characterized by both solid- and liquid-state nuclear magnetic resonance, Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, and contact angle measurements. Further, we investigated the size, shape, and structure morphology of nanostructured fluorinated cellulose esters by dynamic light scattering, scanning electron microscopy, and X-ray diffraction measurements.Peer reviewe

Multi-genome identification and characterization of chlamydiae-specific type III secretion substrates: the Inc proteins

<p>Abstract</p> <p>Background</p> <p><it>Chlamydiae </it>are obligate intracellular bacteria that multiply in a vacuolar compartment, the inclusion. Several chlamydial proteins containing a bilobal hydrophobic domain are translocated by a type III secretion (TTS) mechanism into the inclusion membrane. They form the family of Inc proteins, which is specific to this phylum. Based on their localization, Inc proteins likely play important roles in the interactions between the microbe and the host. In this paper we sought to identify and analyze, using bioinformatics tools, all putative Inc proteins in published chlamydial genomes, including an environmental species.</p> <p>Results</p> <p>Inc proteins contain at least one bilobal hydrophobic domain made of two transmembrane helices separated by a loop of less than 30 amino acids. Using bioinformatics tools we identified 537 putative Inc proteins across seven chlamydial proteomes. The amino-terminal segment of the putative Inc proteins was recognized as a functional TTS signal in 90% of the <it>C. trachomatis </it>and <it>C. pneumoniae </it>sequences tested, validating the data obtained <it>in silico</it>. We identified a <it>macro </it>domain in several putative Inc proteins, and observed that Inc proteins are enriched in segments predicted to form coiled coils. A surprisingly large proportion of the putative Inc proteins are not constitutively translocated to the inclusion membrane in culture conditions.</p> <p>Conclusions</p> <p>The Inc proteins represent 7 to 10% of each proteome and show a great degree of sequence diversity between species. The abundance of segments with a high probability for coiled coil conformation in Inc proteins support the hypothesis that they interact with host proteins. While the large majority of Inc proteins possess a functional TTS signal, less than half may be constitutively translocated to the inclusion surface in some species. This suggests the novel finding that translocation of Inc proteins may be regulated by as-yet undetermined mechanisms.</p

Vibrio cholerae Proteome-Wide Screen for Immunostimulatory Proteins Identifies Phosphatidylserine Decarboxylase as a Novel Toll-Like Receptor 4 Agonist

Recognition of conserved bacterial components provides immediate and efficient immune responses and plays a critical role in triggering antigen-specific adaptive immunity. To date, most microbial components that are detected by host innate immune system are non-proteinaceous structural components. In order to identify novel bacterial immunostimulatory proteins, we developed a new high-throughput approach called “EPSIA”, Expressed Protein Screen for Immune Activators. Out of 3,882 Vibrio cholerae proteins, we identified phosphatidylserine decarboxylase (PSD) as a conserved bacterial protein capable of activating host innate immunity. PSD in concentrations as low as 100 ng/ml stimulated RAW264.7 murine macrophage cells and primary peritoneal macrophage cells to secrete TNFα and IL-6, respectively. PSD-induced proinflammatory response was dependent on the presence of MyD88, a known adaptor molecule for innate immune response. An enzymatically inactive PSD mutant and heat-inactivated PSD induced ∼40% and ∼15% of IL-6 production compared to that by native PSD, respectively. This suggests that PSD induces the production of IL-6, in part, via its enzymatic activity. Subsequent receptor screening determined TLR4 as a receptor mediating the PSD-induced proinflammatory response. Moreover, no detectable IL-6 was produced in TLR4-deficient mouse macrophages by PSD. PSD also exhibited a strong adjuvant activity against a co-administered antigen, BSA. Anti-BSA response was decreased in TLR4-deficient mice immunized with BSA in combination with PSD, further proving the role of TLR4 in PSD signaling in vivo. Taken together, these results provide evidence for the identification of V. cholerae PSD as a novel TLR4 agonist and further demonstrate the potential application of PSD as a vaccine adjuvant

Accurate Prediction of Secreted Substrates and Identification of a Conserved Putative Secretion Signal for Type III Secretion Systems

The type III secretion system is an essential component for virulence in many Gram-negative bacteria. Though components of the secretion system apparatus are conserved, its substrates—effector proteins—are not. We have used a novel computational approach to confidently identify new secreted effectors by integrating protein sequence-based features, including evolutionary measures such as the pattern of homologs in a range of other organisms, G+C content, amino acid composition, and the N-terminal 30 residues of the protein sequence. The method was trained on known effectors from the plant pathogen Pseudomonas syringae and validated on a set of effectors from the animal pathogen Salmonella enterica serovar Typhimurium (S. Typhimurium) after eliminating effectors with detectable sequence similarity. We show that this approach can predict known secreted effectors with high specificity and sensitivity. Furthermore, by considering a large set of effectors from multiple organisms, we computationally identify a common putative secretion signal in the N-terminal 20 residues of secreted effectors. This signal can be used to discriminate 46 out of 68 total known effectors from both organisms, suggesting that it is a real, shared signal applicable to many type III secreted effectors. We use the method to make novel predictions of secreted effectors in S. Typhimurium, some of which have been experimentally validated. We also apply the method to predict secreted effectors in the genetically intractable human pathogen Chlamydia trachomatis, identifying the majority of known secreted proteins in addition to providing a number of novel predictions. This approach provides a new way to identify secreted effectors in a broad range of pathogenic bacteria for further experimental characterization and provides insight into the nature of the type III secretion signal

Analytical solutions for wall slip effects on magnetohydrodynamic oscillatory rotating plate and channel flows in porous media using a fractional burgers viscoelastic model

A theoretical analysis of magnetohydrodynamic (MHD) incompressible flows of Burger's fluid through a porous medium in a rotating frame of reference is presented. The constitutive model of a Burger's fluid is used based on a fractional calculus formulation. Hydrodynamic slip at the wall (plate) is incorporated and a fractional generalized Darcy model deployed to simulate porous medium drag force effects. Three different cases are considered- namely, flow induced by a general periodic oscillation at a rigid plate, periodic flow in a parallel plate channel and finally Poiseuille flow. In all cases the plate (s) boundary (ies) are electrically-non-conducting and small magnetic Reynolds is assumed, negating magnetic induction effects. The well-posed boundary value problems associated with each case are solved via Fourier transforms. Comparisons are made between the results derived with and without slip conditions. 4 special cases are retrieved from the general fractional Burgers model, viz Newtonian fluid, general Maxwell viscoelastic fluid, generalized Oldroyd-B fluid and the conventional Burger’s viscoelastic model. Extensive interpretation of graphical plots is included. We study explicitly the influence on wall slip on primary and secondary velocity evolution. The model is relevant to MHD rotating energy generators employing rheological working fluids

Differences in Trochlear Surface Damage and Wear Between Three Different Total Knee Arthroplasty Designs

© 2017 Elsevier Inc. Introduction Trochlear design plays a role in patellofemoral kinematics. Little is known regarding differences in the contact properties between modern designs. The purpose of the present study was to analyze patellofemoral joint contact by identifying areas of joint surface damage and wear in retrieved femoral components of 3 modern designs. Materials Eighteen retrieved femoral components featuring 3 different modern designs (Triathlon, SIGMA, and GENESIS II) were matched based on time-in-vivo, age, gender, and body mass index. Trochlear wear and surface damage were assessed using visual inspection, light microscopy, and light profilometry. Results Visual inspection of the femoral components showed evidence of surface damage in all implant types. No significant differences between the groups were found with respect to surface damage and wear on visual inspection. Light profilometry of retrieved components showed that retrieved Triathlon (P =.002) and SIGMA (P =.009) components were significantly rougher than the corresponding reference components. The GENESIS II retrieved components were not substantially rougher than the reference components (P =.48). Light profilometry analysis showed significantly increased roughness of retrieved SIGMA components compared with Triathlon or GENESIS II components, particularly in the proximal trochlear groove and the medial trochlea. Conclusion As the volume and patient demands for total knee arthroplasty increase, a greater understanding of the patellofemoral joint is warranted. Patellofemoral kinematics can have an effect on the surface characteristics of total knee arthroplasty components. Retrieved SIGMA components appeared to have increased roughness compared with Triathlon or GENESIS II components. The etiology and long-term effects of increased trochlear roughness require further investigation

Current Total Knee Designs: Does Baseplate Roughness or Locking Mechanism Design Affect Polyethylene Backside Wear?

© 2017, The Association of Bone and Joint Surgeons®. Background: Tibial baseplate roughness and polyethylene-insert micromotion resulting from locking-mechanism loosening can lead to polyethylene backside wear in TKAs. However, many retrieval studies examining these variables have evaluated only older TKA implant designs. Questions: We used implant-retrieval analysis to examine if there were differences in: (1) backside damage scores, (2) backside damage modes, and (3) backside linear wear rates in five TKA implant designs owing to differing baseplate surface roughness and locking mechanisms. Additionally, we examined if (4) patient demographics influence backside damage and wear. Methods: Five TKA implant models (four modern and one historical design) were selected with different tibial baseplate and/or locking mechanism designs. Six tibial inserts retrieved at the time of revision from each TKA model were matched for time in vivo, age of the patient at TKA revision, BMI, sex, revision number, and revision reason. Each insert backside was analyzed for: (1) visual total damage score and (2) individual visual damage modes, both by two observers and with an intraclass correlation coefficient of 0.66 (95% CI, 0.39–0.92), and (3) linear wear rate measured by micro-CT. Median primary outcomes were compared among the five designs. For our given sample size among five groups we could detect with 80% power a 10-point difference in damage score and an 0.11-mm per year difference in wear rate. Results: The polished tibial design with a partial peripheral capture locking mechanism and anterior constraint showed a lower total damage score compared with the nonpolished tibial design with only a complete peripheral-rim locking mechanism (median, 12.5; range, 9.5–18.0; 95% CI, 9.58–16.42 versus median, 22.3; range, 15.5–27.0; 95% CI, 17.5–26.5; p = 0.019). The polished baseplate with a tongue-in-groove locking mechanism showed more abrasions than the nonpolished baseplate with a peripheral-rim capture and antirotational island (median, 7.25; range, 0.5–8.0; 95% CI, 2.67–8.99 versus median, 0.75; range, 0–1.5; 95% CI, 0.20–1.47; p = 0.016)). Dimpling was a unique wear mode to the nonpolished baseplates with the peripheral-rim capture and antirotational island (median, 5.5; range, 2.0–9.0; 95% CI, 2.96–8.38) and the peripheral-rim capture alone (median, 9.0; range, 6.0–10.0; 95% CI, 7.29–10.38). Overall, the linear wear rate for polished designs was lower than for nonpolished designs (0.0102 ± 0.0044 mm/year versus 0.0224 ± 0.0119 mm/year; p \u3c 0.001). Two of the polished baseplate designs, the partial peripheral capture with anterior constraint (median, 0.083 mm/year; range, 0.0037–0.0111 mm/year; 95% CI, 0.0050–0.0107 mm versus median, 0.0245 mm/year; range, 0.014–0.046 mm/year; 95% CI, 0.0130–0.0414 mm; p = 0.008) and the tongue-in-groove locking mechanism (median, 0.0085 mm/year; range, 0.005–0.015 mm/year; 95% CI, 0.0045–0.0138 mm; p = 0.032) showed lower polyethylene linear wear rates compared with the nonpolished baseplate design with only a peripheral-rim capture. Conclusions: Total damage scores and linear wear rates were highest involving the nonpolished design with only a peripheral rim capture. There were no differences among the other TKA designs regarding damage and wear, but this finding should be considered in the setting of a relatively small sample size. Clinical Relevance: Our study showed that in the complex interplay between baseplate surface finish and locking mechanism design, a polished baseplate with a robust locking mechanism had the lowest backside damage and linear wear. However, improvements in locking mechanism design in nonpolished baseplates potentially may offset some advantages of a polished baseplate. Further retrieval analyses need to be done to confirm such findings, especially analyzing current crosslinked polyethylene. Additionally, we need mid- and long-term studies comparing TKA revisions attributable to wear and osteolysis among implants before understanding if such design differences are clinically relevant