Biodegradation of Natural Rubber and Natural Rubber Products by <Emphasis Type="Italic">Streptomyces</Emphasis> sp. Strain CFMR 7

The rubber degrading activity of Streptomyces sp. CFMR 7 whose whole genome sequence was recently determined was tested with non-vulcanized fresh latex and common vulcanized rubber products such as latex glove, latex condom and latex car tyre. The degradation activity was unequivocally demonstrated by scanning electron microscopy with respect to microbial colonization efficiency, disintegration of rubber material and biofilm formation after 3, 6 and 9 months of inoculation. Fourier transform infrared spectroscopy comprising the attenuated total reflectance analysis on these inoculated products revealed insights into the biodegradation mechanism of this strain whereby, a decrease in the number of cis -1,4 double bonds in the polyisoprene chain, the appearance of ketone and aldehyde groups formation indicating an oxidative attack at the double bond of rubber hydrocarbon. In the presence of strain Streptomyces sp. CFMR 7, gel permeation chromatography analysis revealed a significant shift of the molecular weight distribution to lower values. Clear decrease in the molecular weight was observed over 3, 6 and 9 months of cultivation on fresh latex samples compared to other vulcanized products. No shift in the molecular weight distribution was observed for non-inoculated control. These results clearly showed that Streptomyces sp. CFMR 7 was able to cleave the carbon backbone of poly (cis -1,4-isoprene). Although this strain was able to degrade both non-vulcanized and vulcanized rubber products, faster degradation was obtained with natural rubber and rubber products with low complexity.     

Statistical Optimization of Polyhydroxybutyrate Production by <Emphasis Type="Italic">Bacillus Pumilus</Emphasis> H9 Using Cow Dung as a Cheap Carbon Source by Response Surface Methodology

A gram positive bacterium (designated strain H9) found to be a potential polyhydroxybutyrate (biodegradable polymer) producer was isolated from the soil samples of a stress prone environment (municipal waste areas). This bacterium was identified as Bacillus pumilus H9 from its morphological, physiological and 16S rRNA gene sequence analysis. A four-factor central composite rotary design was employed to optimize the medium and to find out the interactive effects of four variables, viz. concentrations of cow dung, sucrose, peptone and pH on PHB production. Using response surface methodology, a second-order polynomial equation was obtained by multiple regression analysis and a yield of 2.47 g/L of PHB dry weight was achieved from the optimized medium at pH 7. Here, we report cow dung as a cheap carbon source for the production of PHB. Further, phbA, phbB and phbC genes were amplified by polymerase chain reaction which confirms the bacterium to be able to produce polyhydroxybutyrate.     

Biodegradation of Poly-ε-caprolactones and Poly-<Emphasis Type="SmallCaps">l</Emphasis>-lactides by Fungi

This work assessed biodegradation, by Aspergillus, Fusarium, Penicillium and Parengyodontium fungi, of four samples of poly-ε-caprolactone (PCL), three samples of poly-l-lactide (PLA) and one sample of poly-d,l-lactide (DL-PLA) produced by ring-opening polymerization initiated by aluminium complexes of corresponding lactones. Mesophilic fungal strains actively biodegrading PCL (F. solani) and PLA (Parengyodontium album and A. calidoustus) were selected. The rate of degradation by the selected fungi was found to depend on the physicochemical and mechanical properties of the polymers (molecular weight, polydispersity, crystallinity). The most degradable poly-ε-caprolactone sample was shown to have the lowest molecular weight; the most biodegradable polylactide DL-PLA had the lowest crystallinity. Mass spectral analysis of biodegraded polymer residues showed PCL to be degraded more intensively than PLA. It is established that in the case of Parengyodontium album the colonization of the films of polypropylene composites with DL-PLA is observed, which will undoubtedly contribute to their further destruction under the influence of abiotic factors in the environment.     

Preparation and Characterization of Polyaniline and Ag/ Polyaniline Composite Nanoporous Particles and Their Antimicrobial Activities

Polyaniline (PANI) and Ag/PANI nanoporous composite were prepared by an oxidative polymerization method. The oxidation process of PANI nanoparticles was occurred using (NH₄)₂S₂O₈ while the oxidation process of Ag/PANI nanoporous composite was occurred using AgNO₃ under the effect of artificial radiation. The structural, morphological, and optical properties of the PANI and Ag/PANI nanoporous structures were studied using different characterization tools. The results confirm the formation of polycrystalline nanoporous PANI and spherical nanoporous composite of Ag/PANI particles. Antibacterial activity tests against gram-positive bacteria, Bacillus subtilis and Staphylococcus aureus, and gram-negative bacteria, Escherichia coli, and Salmonella species were carried out using different concentrations of PANI nanoparticles and Ag/PANI nanoporous composites. PANI has not antibacterial effect against all studied pathogens. In contrast, Ag/PANI nanoporous composites possessed antibacterial activity that is identified by the zone of inhibition. The inhibition zones of bacteria are in order; Salmonella species?>?S. aureus?>?B. subtilis?>?E. coli. The inhibition zones of all bacteria increased with increasing concentrations of Ag/PANI nanoporous composites from 200 to 400 ppm then decreased with further increasing of the dose concentrations to 600 ppm. Finally, a simplified mechanism based on the electrostatic attraction is presented to describe the antimicrobial activity of Ag/PANI nanoporous composite.     

Comparative fertilizer properties of digestates from mesophilic and thermophilic anaerobic digestion of dairy manure: focusing on plant growth promoting bacteria (PGPB) and environmental risk

The fertilizer properties of anaerobic digestate depend on the feedstock and operating conditions of digestion. In this study, the comparative fertilizer properties of mesophilic and thermophilic digestates from dairy manure were evaluated for plant nutrient contents, and special attention was paid to plant growth promoting bacteria (PGPB). Two digestates contained similar plant nutrient contents, while the thermophilic digestate contained higher contents of NH₄⁺–N. The quantity of Bacillus and Pseudomonas in the mesophilic digestate was significantly higher than in the thermophilic digestate. Furthermore, Bacillus showed siderophore production and antifungal activity (43.5–75.3%), and Pseudomonas showed siderophore and phytohormone production (4.2–75.2 µg ml^?1). One phosphate solubilizing isolate was also detected in the mesophilic digestate. These results indicated that two digestates showed different fertilizer properties with respect to nutrient contents and PGPB, and digestates had the potential to increase the availability of phosphorus and iron in the soil, both to provide phytohormones to plant roots and protect plants from fungal phytopathogens. The contents of indicator bacteria and heavy metals were analyzed to determine their environmental risk, and the results showed a high reduction in indicator bacteria and lower levels of heavy metals than in other feedstocks.     

Devulcanization of Ground Tires by Different Strains of Bacteria: Optimization of Culture Condition by Taguchi Method

Biological devulcanization of ground tires (GTs) was evaluated by eleven different bacteria belonging to the genera Thiobacillus, Gordonia, Nocardia, Amycolaptopsis and Pseudomonas. The GTs were treated by each bacterium in a mineral medium and devulcanization was measured by increasing the sulfate of the medium and decreasing the sulfur of the GTs. The effects of incubation time (10 and 20 days) and the percent of ground tire in the medium (0.5 and 5 w/v %) on desulfurization were investigated. No significant changes were observed after 10 days of incubation. The total sulfur contents of all bio-treated GTs were decreased by 6–21% in 0.5% GTs after 20 days of incubation. While in 5% GTs, the total sulfur contents were mainly decreased using Thiobacillus ferroxidans DSMZ 583 and PTCC 1647 up to 27 and 15%, respectively. SEM photograph further indicated a good coherency interface between the bacteria and the GTs. Subsequently, Taguchi method was applied for the optimization of the culture condition of DSMZ 583. An L12 orthogonal array was performed by which the effects of eleven factors in two levels were evaluated. It was found that the amount and mesh size of GTs are the most important factors in biological devulcanization of ground tires.     

Synthesis,Characterization and Application of Biodegradable Crosslinked Carboxymethyl Chitosan/Poly(Ethylene Glycol) Clay Nanocomposites

Crosslinked carboxymethyl chitosan (CMCh)/poly(ethylene glycol) (PEG) nanocomposites were synthesized using terephthaloyl diisothiocyanate as a crosslinking agent, in presence of montmorillonite (MMT), in different weight ratios of the two matrices. Characterization of nanocomposites was performed using different analyses. Swelling behavior was studied in different buffered solutions. It was found that formation of crosslinked CMCh/PEG nanocomposites increased the swell ability. Metal ions adsorption had also been investigated. The results indicated that crosslinked CMCh adsorbs various metal ions much more than non-crosslinked CMCh. Antimicrobial activity was examined against Gram-positive bacteria (S. aureus (RCMB 010027) and S. Pyogens (RCMB 010015), Gram-negative bacteria (E. coli (RCMB 010056), and also against fungi (A. fumigates (RCMBA 02564, G. candidum (RCMB 05096) and C. albicans (RCMB 05035). Data indicated that most of these nanocomposites exhibited good antimicrobial potency. Degradation studies were carried out in simulated body fluid for different time periods in order to find out the degradation index. Results showed that weight loss (%) of most of the nanocomposites increased as a function of incubation time.     

New Poly(aniline-<Emphasis Type="Italic">co</Emphasis>-<Emphasis Type="Italic">o</Emphasis>-phenylenediamine)/Kaolinite Microcomposites for Water Decontamination

Copolymers of aniline and o-phenylenediamine/kaolinite composites were synthesized by 5:1 molar ratios of the respective monomers with different percentages of nanoclay via modified in situ chemical co-polymerization. The results were verified by measuring the FT-IR and UV–vis absorption spectra for PANI-o-PDA/kaolinite composites. The thermal behaviour of the copolymer and composites was studied. PANI-o-PDA/kaolinite composites were thermally more stable than pure copolymer. Surface morphology of copolymer composites was recorded at different magnification power by SEM which revealed whitish micrometric beads distributed all over the field with particle size in the range of 0.122–0.233 μm. This work demonstrates that the PANI-o-PDA/kaolinite composites particles can be considered as potential adsorbents for hazardous and toxic metal ions of water from lake El-Manzala, Egypt. All of Cd(II), Cu(II), and Pb(II) posed dangerous health risk to the local population via fish consumption.     

Water Absorption Kinetics and Hygrothermal Aging of Poly(lactic acid) Containing Halloysite Nanoclay and Maleated Rubber

Poly(lactic acid)/halloysite nanoclay composites (PLA/HNC) containing maleic anhydride grafted styrene-ethylene/butylene-styrene (SEBS-g-MAH) were produced using melt compounding followed by compression molding. The effects of hygrothermal aging on the thermal properties and functional groups changes of the HNC reinforced PLA (with and without SEBS-g-MAH) at three different temperatures (i.e., 30, 40 and 50 °C) were analyzed using differential scanning calorimetry and Fourier transform infrared spectroscopy techniques. The diffusion coefficient (D) of PLA was decreased by the incorporation of HNC and SEBS-g-MAH. The activation energy of water diffusion (E _a ) of PLA/HNC/SEBS-g-MAH nanocomposites was higher than that of pure PLA. The glass transition temperature (T _g ), cold-crystallization temperature (T _cc ) and melting temperature (T _m ) of the PLA sample were shifted to lower temperature and the effect was more pronounced at 50 °C. The carbonyl index values of all PLA samples increased after immersed in 40 and 50 °C, which is due to the formation of higher amount of carboxyl groups during the hydrolysis process.     

Degradation Mechanism of CF/EP Composites in Supercritical <Emphasis Type="Italic">n</Emphasis>-Butanol with Alkali Additives

CF/EP (carbon fibre/epoxy resin) composites were degraded by supercritical n-butanol with alkali additive KOH in a batch reactor. The catalytic degradation mechanism of the composites was investigated based on the analysis of liquid phase products by GC–MS and solid phase products by FTIR. The results indicate that alkali additive (KOH) can promote Guerbet reaction and increase hydrogen donor capability of supercritical n-butanol. The H^· can combine promptly with the free radical formed by the scission of linear and crosslinked chains in epoxy resin to generate the liquid products, including phenol, 4-isopropylphenol, 4-(2-methylallyl)phenol and other derivatives of benzene and phenol. The combination of supercritical n-butanol with alkali additive is an effective way to degrade and recycle CF/EP composites.     

Comparison of three ornamental plants for phytoextraction potential of chromium removal from tannery sludge

Based on pre-experimentation, three ornamental plants, Mirabilis jalapa, Impatiens Balsamin (I. Balsamin) and Tagetes erecta L., were selected as target plants to study the phytoextraction of chromium (Cr) in tannery sludge irrigated with four treatments according to Cr concentration gradient [Control (CK); 20.50 × 10³ mg kg^?1 (T1); 51.25 × 10³ mg kg^?1 (T2); 102.50 × 10³ mg kg^?1 (T3)]. Results of pot experiments showed that the biomass of Mirabilis jalapa and Tagetes erecta L. had no significant differences among the four treatments, while I. Balsamin showed a decline trend in the biomass with the increase of Cr concentration, probably due to some extent to the poisoning effect of Cr under treatment T2 or T3. Mirabilis jalapa accumulated Cr concentration, with 408.97, 124.97, 630.16 and 57.30 mg kg^?1 in its roots, stems, leaves and inflorescence, respectively. The translocation factor and the bioaccumulation coefficient of Mirabilis jalapa are each greater than 1, indicating that Mirabilis jalapa has the strong ability to tolerate and enrich Cr by biological processes. Comparing accumulation properties of the three ornamental plants, in the amount and allocation, Mirabilis jalapa showed the highest phytoextraction efficiency and could grow well at the high Cr concentration. Our experiments suggest that Mirabilis jalapa is the expected flower species for Cr removal from tannery sludge.     

Potential of <Emphasis Type="Italic">pinhão</Emphasis> Coat as Constituents of Starch Based Films Using Modification Techniques

The potential of lignocellulosic fibers obtained by dry grinding of pinhão coat as fillers in starch filmogenic solutions for packaging applications was evaluated in this work. To improve the incorporation of this waste into the starch solutions different physical and chemical treatments were conducted. Thereafter, morphology, chemical structure, crystallinity and water absorption of the pinhão coat powders were determined. The composites were also characterized regarding their morphology, chemical structure, crystallinity, mechanical properties, water vapor permeability and hydrophilicity. Poor fiber/matrix adhesion and high water absorption of the fibers were evidenced. Consequently, water vapor permeability of composites was increased by incorporating the fibers. Moreover, mechanical properties were improved and the morphological results were used to support the water absorption differences among the powders. Regarding the food packaging applications, starch/pinhão coat composites appeared as promising materials to reach the requirements of respiring food products.     

Biosynthesis of Poly(3-hydroxybutyrate) from Cheese Whey by <Emphasis Type="Italic">Bacillus megaterium</Emphasis> NCIM 5472

Microbial polyhydroxyalkonate such as homopolyester of poly(3-hydroxybutyrate) (PHB) was produced from cheese whey by Bacillus megaterium NCIM 5472. Due to their numerous potential industrial applications, the focus was given to competently enhance the amount of PHB produced. The amount of PHB produced from whole cheese whey, and ultrafiltered cheese whey was first compared, and after observing a rise in PHB production by using ultrafiltered cheese whey, cheese whey permeate was chosen for further analysis. The presence of PHB was then confirmed by GCMS. Since the main aim of the study was to increase the amount of PHB produced through batch fermentation, various process parameters like time, pH, C/N ratio, etc. were optimized. After optimization, it was found that B. megaterium NCIM 5472 was capable of accumulating 75.5% of PHB of its dry weight and a PHB yield of 8.29 g/L. The chemical structure of the polymer was further analyzed by using FTIR and NMR spectroscopy methods. Also, the physical and thermal properties were studied by using Differential scanning calorimetry and Thermogravimetric analysis. It was found that the polymer produced had excellent thermal stability, thus allowing the possibility to exploit its properties for industrial purposes such as adhesives, packaging materials, etc.     

Kinetic Analysis of the Temperature Effect on Polyhydroxyalkanoate Production by <Emphasis Type="Italic">Haloferax mediterranei</Emphasis> in Synthetic Molasses Wastewater

Haloferax mediterranei is an extremely halophilic archaeon that is able to synthesize polyhydroxyalkanoate (PHA) in high salt environment with low sterility demand. In this study, a mathematical model was validated and calibrated for describing the kinetic behavior of H. mediterranei at 15, 20, 25, and 35 °C in synthetic molasses wastewater. Results showed that the production of PHA by H. mediterranei, ranging from 390 to 620 mg h^?1 L^?1, was strongly dependent on the temperature. The specific growth rate (µ _max), specific substrate utilization rate (q _max), and specific decay rate (k _d) of H. mediterranei increased with temperature following Arrhenius equation prediction. The estimated activation energy was 58.31, 25.59, and 22.38 kJ mol^?1 for the process of cell growth, substrate utilization, and cell decay of H. mediterranei, respectively. The high temperature triggered the increased PHA storage even without nitrogen limitation. Thus, working at high temperatures seems a good strategy for improving the PHA productivity of H. mediterranei.     

Antimicrobial Activity of Polyhexamethylene Guanidine Derivatives Introduced into Polycaprolactone

The research was aimed at determining the abundance of biofilm formation by Escherichia coli and Staphylococcus aureus on the surface of polycaprolactone (PCL) with polyhexamethylene guanidine (PHMG) derivatives and effect of the derivatives on extracellular hydrolytic enzymes and intracellular dehydrogenases. Biofilm abundance was determined by spectrophotometry, using crystal violet staining. Hydrolytic enzymes after contact with the film were determined with the use of non-specific substrate—fluorscein diacetate. The effect of PHMG derivatives on dehydrogenases activity was assessed using the test, where triphenyltetrazolium chloride (TTC) is reduced to triphenylformazan (TF). The PCL containing PHMG granular polyethylene wax and salt of sulfanilic acid (0.6–1% wt.) strongest inhibited biofilm formation. PHMG derivatives introduced into PCL were found to slightly affect hydrolases activity in both E. coli and S. aureus at a concentration of 0.2 and 0.6%. It was also found that dehydrogenases activity was inhibited by PCL films containing PHMG derivatives. PCL containing 1% of PHMG sulfanilate strongest inhibited hydrolases activity, whereas PCL modified with 1% of PHMG granular polyethylene wax showed the highest inhibitory effect on the activity of both enzymes. W-PCL and A-PCL composites (at concentration of 0.6%) have optimal combination of antibiofilm activity and biodegradability.     

Adsorption of Crystal Violet Dye from Aqueous Solution by Poly(Acrylamide-<Emphasis Type="Italic">co</Emphasis>-Maleic Acid)/Montmorillonite Nanocomposite

Poly(acrylamide-co-maleic acid)/montmorillonite nanocomposites, were synthesized via in situ polymerization with different maleic acid and MMT content. The capability of the hydrogel for adsorption of crystal violet (CV) was investigated in aqueous solutions at different pH values and temperatures. The pseudo-second-order kinetics model could fit successfully the adsorption kinetic data. The effects of maleic acid to acrylamide molar ratio (MA_R), weight percent of MMT (MMT%), the pH of medium and the solution temperature (T) on the CV adsorption capacity (q _e ) of adsorbents were studied by Taguchi experimental design approach. The results indicated that increasing the MMT% leads to a greater q _e . The q _e value of adsorbents increased also with increasing both MA_R and pH, while reduced when the temperature of medium increased. The relatively optimum conditions to achieve a maximum CV adsorption capacity for P(AAm/MA)/MMT adsorbents were found as: 0.06 for MA_R and 5 % of MMT%, medium pH = 7 and T = 20 °C.     

Selective Lead(II) Adsorption and Flocculation Characteristics of the Grafted Sodium Alginate: A Comparative Study

Synthesis of sodium alginate-g-poly(acrylamide-co-N-methylacrylamide) [S-III], sodium alginate-g-poly(N-methylacrylamide-co-N,N-dimethylacrylamide) [S-II], sodium alginate-g-poly(acrylamide-co-N,N-dimethylacrylamide) [S-I]. Sodium alginate-g-poly(N,N-dimethylacrylamide) [SAG-g-PDMA] and sodium alginate-g-poly(acrylamide) [SAG-g-PAM] were prepared by solution polymerization technique using potassium peroxydisulfate as the initiator at 70?°C in water medium. The graft copolymers were characterized by FTIR and NMR (¹H and ¹³C) spectroscopy, SEM and XRD studies. All the five graft copolymers were used to remove Pb(II) ions from the aqueous solution and also in flocculation studies of kaolin clay (1.0 wt%), silica (1.0 wt%) and iron ore slime (0.25 wt%) suspensions. A comparative studies of all the five graft copolymers were also made in both the two cases. The Pb(II) ion removal capacity of all the graft copolymers follows the order S-III?>?SAG-g-PAM?>?S-II?>?SAG-g-PDMA?>?S-I. But the flocculation performance of the graft copolymers follows the order S-II?>?S-I?>?S-III?>?SAG-g-PDMA?>?SAG-g-PAM. S-III was also used for the competitive metal ion removal with Hg(II), Cd(II), Cu(II) and Zn(II). Pb(II) adsorption of S-III (the best Pb(II) ion adsorber) follows pseudo second order rate equation and Langmuir adsorption isotherm.     

Production,Characterization and Bioemulsifying Activity of an Exopolysaccharide Produced by <Emphasis Type="Italic">Sphingomonas</Emphasis> sp. Isolated from Freshwater

This study aimed to evaluate the emulsion stability of solutions containing exopolysaccharide and culture medium of a Sphingomonas sp. strain with various hydrophobic compounds. The exopolysaccharide characterized belongs to a sphingan group, however, not being a gellan gum as produced by certain Sphingomonas strains. In general, the emulsifying indexes found in this study were above 70% for gasoline, hexane, kerosene and used frying oil. Nonetheless, the best results were achieved in kerosene solutions, which showed an index of 80% after 24 h, remaining stable for more than 168 h in combinations with various EPS concentrations. Interestingly, diesel oil best results were singly achieved in solution pH of 11, showing an index of around 65%. Furthermore, hexane obtained an index of 100% after 24 h when culture medium was used. Thus, these findings highlight the use of EPS as a potential bioemulsifier agent to enhance hydrocarbon degradation and emulsification effects in environmental biotechnology.     

Microbial Degradation of UV-Pretreated Low-Density Polyethylene Films by Novel Polyethylene-Degrading Bacteria Isolated from Plastic-Dump Soil

Eleven effective low-density polyethylene (LDPE)-degrading bacterial strains were isolated and identified from landfill soil containing large amounts of plastic materials. The isolates belonged to 8 genera, and included Pseudomonas (areroginosa and putida), Sphingobacterium (moltivorum), Delftia (tsuruhatansis), Stentrophomonas (humi and maltophilia), Ochrobacterum (oryzeae and humi), Micrococcus (luteus), Acinetobacter (pitti), and Citrobacter (amalonaticus). Abiotic degradation of LDPE films by artificial and natural ultraviolet (UV)-exposure was analyzed by FT-IR spectroscopy. LDPE films treated with UV-radiation were also inoculated with the isolates and biofilm production and LDPE degradation were measured. Surface changes to the LDPE induced by bacterial biofilm formation were visualized by Scanning Electron Microscopy. The most active bacterial isolate, IRN19, was able to degrade polyethylene film by 26.8?±?3.04% gravimetric weight over 4 weeks. Analysis of 16S rRNA sequence of this isolate revealed 96.97% similarity in sequence to Acinetobacter pitti, which has not previously been identified as a polyethylene-degrading bacterium. Also, most the effective biofilm forming isolate, IRN11, displayed the highest cell mass production (6.29?±?0.06 log cfu/cm²) after growth on LDPE films, showed 98.74% similarity to Sphingobacterium moltivourum.     

Accelerated Stability Testing of a Polyherbal Transdermal Patches Using Polyvinyl Alcohol and Hydroxypropyl Methylcellulose as a Controlling Polymer Layer

The present work was to evaluate the stability potential of (E)-4-(3,4-dimethoxyphenyl)but-3-en-l-ol (Compound D) in polyherbal transdermal patches. The polyherbal formulation composed of the rhizomes of Zingiber cassumunar and Curcuma longa, leaves and stems of Cymbopogon citratus, rind and leaves of Citrus hystrix fruit, and leaves of Acacia rugata and Tamarindus indica. Polyvinyl alcohol and hydroxypropyl methylcellulose were used as a matrix film, and glycerine was used as a plasticizer. Stability testing was established for 6 months under accelerated conditions as according to International Conference on Harmonisation guidelines. Mechanical properties, moisture uptake, swelling ratio, and in vitro studies were evaluated. New Zealand white rabbits were used as the animal model. Results obtained after 6 months showed that the polyherbal transdermal patches were stable, with a good mechanical properties and hydrophilicity. In vitro study kinetics for active Compound D fitted to the Higuchi model for both release and skin permeation. The transdermal patch containing polyherbal formulation was safe to apply on the skin without irritation. Thus, transdermal patches containing this polyherbal formulation had good stability potential, with no irritation on application.