Azidated Ether-Butadiene-Ether Block Copolymers as Binders for Solid Propellants

Polymeric binders for solid propellants are usually based on hydroxyl-terminated polybutadiene (HTPB), which does not contribute to the overall energy output. Azidic polyethers represent an interesting alternative but may have poorer mechanical properties. Polybutadiene–polyether copolymers may combine the advantages of both. Four different ether-butadiene-ether triblock copolymers were prepared and azidated starting from halogenated and/or tosylated monomers using HTPB as initiator. The presence of the butadiene block complicates the azidation step and reduces the storage stability of the azidic polymer. Nevertheless, the procedure allows modifying the binder properties by varying the type and lengths of the energetic blocks.     

Studies on a Novel Thermoplastic Polyurethane as a Binder for Extruded Composite Propellants

Extruded composite propellant (ECP) is an entirely new thrust area in the development of composite propellants within India. These are based on high-density thermoplastic elastomers as a propellant binder with ammonium perchlorate (AP) as an oxidizer and aluminum (Al) as a metallic fuel. Thus, this class of propellant not only provides higher energy but also yields higher density impulse. There are no pot life problems as with conventional slurry cast composite propellants because the binder used is thermoplastic in nature and hence can be recycled. ECP can take up solid loadings up to 90% and have very good dimensional stability.

The present article reports evaluation of a thermoplastic polyurethane, viz. Irostic, as a binder for extruded composite propellants. The polymer was characterized completely before use. The feasibility of propellant processing has been studied and processing parameters have been established. Around 50 propellant formulations are processed for selection and optimization of plasticizer and to investigate the effect of variations in binder content. The results of the propellant characterizations have shown that the binder is capable of imparting significant improvements in mechanical properties and high density. Data generated on burning rate and static evaluation has confirmed that the binder imparts mesa-burning characteristics to the propellant with relatively low temperature sensitivity of burn rate.     

Copper Chromite as Ballistic Modifier in a Typical Solid Rocket Propellant Composition: A Novel Synthetic Route Involved

Present report emphasises the importance of employing a nano-copper chromite having an excess cupric oxide (CUCRO) as a ballistic modifier in a typical solid rocket propellant (SRP) composition. The CUCRO synthesised from a modified combustion route through decomposition of the alginate mixed metal complex is employed in the present investigation. The changes occurring in the mechanical properties of the propellant strands on addition of the CUCRO modifier are studied. Different morphologies are observed, which contribute towards the toughened propellant composition. The ballistic studies are undertaken in the presence and absence of CUCRO.     

Oil soluble polymers as a viscosity-reducing agent for super heavy oil

We, the Editor and the Publisher of Petroleum Science and Technology, have retracted the following article:

Li-Yan Pan, Guo-Qing Feng, Jin-cheng Mao &; Hai-Bin Wang. “Oil soluble polymers as a viscosity-reducing agent for super heavy oil,” Petroleum Science and Technology, Volume 35, 2017, Issue 8, pages 747–753. doi:10.1080/10916466.2016.1273240

We are now cognizant of the fact that the above article has substantial text-matching with the following article, to which no attribution was made:

Jincheng Mao, Jiawei Liu, Haibin Wang, Xiaojiang Yang, Zhaoyang, Bo Yang &; Jinzhou Zhago. “Novel terpolymers as viscosity reducing agent for Tahe super heavy oil,” RSC Advances, Volume 7, 2017, Issue 31, pages 19257–19261.

It is therefore not deemed to be an original contribution. We note the breach of warranties made by the authors with respect to originality and provenance, and of our policy on publishing ethics and integrity. We note that we received, peer-reviewed, accepted, and published the article in good faith based on these warranties, and censure this action.

We have been informed in our decision-making by our policy on publishing ethics and integrity and the COPE guidelines on retractions. The retracted article will remain online to maintain the scholarly record, but it will be digitally watermarked on each page as “Retracted”.     

Characteristics of coliphage ECP4 and potential use as a sanitizing agent for biocontrol of Escherichia coli O157:H7

Escherichia coli O157:H7 is an important pathogenic bacterium to humans because it produces various toxins, such as shiga-toxin. Coliphage ECP4, which belongs to the Siphoviridae family, was isolated from bovine feces to test its utility as a potential agent for the biocontrol of E. coli O157:H7. The burst size of coliphage ECP4 was about 80 PFU/cell, after a latent period of 30–35 min. Coliphage ECP4 was susceptible to temperatures above 70 °C; however, its stability was slightly reduced to 1–2 log PFU/ml after 30 min in 70% ethanol. In addition, the shiga toxin gene was not detected on coliphage ECP4. Coliphage ECP4 inhibited the growth of E. coli O157:H7 in vegetable juice, and was not detected in cabbage after 5 h. When coliphage ECP4 was applied to biofilm-formed E. coli O157:H7, E. coli O157:H7 was efficiently reduced. The newly identified coliphage ECP4 might effectively reduce E. coli O157:H7 or its biofilmed-form. Therefore, the coliphage ECP4 might be an efficient sanitizer for fresh produce contaminated with E. coli O157:H7 in the biofilm environment.     

The preparation of an amino acid-based surfactant and its potential application as an EOR agent

Most of the synthetic surfactants investigated with the aim of enhanced chemically oil recovery in the literature have environmental drawbacks. In this work, application of an environmentally-friendly synthetic surfactant as an enhanced oil recovery agent is introduced by measuring interfacial tension of water–kerosene systems and wettability alteration of carbonate pellets. For this purpose, an amino acid-based surfactant was initially synthesized using a new synthetic approach which was subsequently confirmed by spectra of Fourier transform infrared and Proton nuclear magnetic resonance. Results showed a value of critical micelle concentration in the range of 9000–9100 ppm for this surfactant. Results also demonstrated a decrease of 38.53% in water–kerosene system interfacial tension and a 17.76% reduction in oil-wetness of the carbonate pellets.     

Thermo-sensitive polymer nanospheres as a smart plugging agent for shale gas drilling operations

Emulsifier-free poly(methyl methacrylate–styrene) [P(MMA–St)] nanospheres with an average particle size of 100 nm were synthesized in an isopropyl alcohol–water medium by a solvothermal method. Then, through radical graft copolymerization of thermo-sensitive monomer N-isopropylacrylamide(NIPAm) and hydrophilic monomer acrylic acid(AA) onto the surface of P(MMA–St) nanospheres at 80 °C, a series of thermo-sensitive polymer nanospheres, named SD-SEAL with different lower critical solution temperatures(LCST), were prepared by adjusting the mole ratio of NIPAm to AA. The products were characterized by Fourier transform infrared spectroscopy, transmission electron microscopy, thermogravimetric analysis, particle size distribution, and specific surface area analysis. The temperature-sensitive behavior was studied by light transmittance tests, while the sealing performance was investigated by pressure transmission tests with Lungmachi Formation shales. The experimental results showed that the synthesized nanoparticles are sensitive to temperature and had apparent LCST values which increased with an increase in hydrophilic monomer AA.When the temperature was higher than its LCST value, SDSEAL played a dual role of physical plugging and chemical inhibition, slowed down pressure transmission, and reduced shale permeability remarkably. The plugged layer of shale was changed to being hydrophobic, which greatly improved the shale stability     

Novel polymeric nanogel as diversion agent for enhanced oil recovery

The authors discuss the nanogel application as deep diversion agent for enhanced oil recovery (EOR). Experimental studies of nanogel show that its utilization allows combining the advantages of gels used in bulk and sequential injection. Addition of light metal nanoparticles subsequently increases the gel system strength while crosslinking, however it has no impact on flow ability of polymer solution. The nanogels application as deep diversion agent for EOR was studied in treatment experiments at two crossflow layered artificial cores. Nanoparticle addition increases residual resistance factor of polymer gel up to 22% and show a more long-lasting effect. Oil recovery increase for nanogel application was 6% original oil in place (OOIP) in comparison with gel without nanoparticles. It has been shown the gel bank's position impact on oil recovery efficiency at in situ fluid diversion operations. The series of experiments for both types of gels with three different gel blank positions were conducted. Experimental results showed the best value of 19% and 28% OOIP recovery increase in near production line position for gel and nanogels, respectively.     

Investigations on the essential oil of Lippia rugosa from Cameroon for its potential use as antifungal agent against Aspergillus flavus Link ex. Fries

Lippia rugosa essential oil was tested for its effectiveness against Aspergillus flavus on artificial growth media. The chemical composition of the oil was determined by gas chromatography–mass spectrometry (GC–MS). Geraniol (51.5%), nerol (18.6%) and geranial (10.4%) were the main components of Lippia oil. After 8 days of incubation on essential oil supplemented medium, mycelium growth of A. flavus was totally inhibited by 1000 mg l^?1 of L. rugosa essential oil. The effect of essential oil on aflatoxin B₁ synthesis was evaluated in SMKY broth. The medium supplemented with different essential oil concentrations, was inoculated with A. flavus mycelium and incubated at 25 °C. After 2, 4, 6 and 8 days, aflatoxin B₁ (AFB₁) was quantified in the supernatant using Enzyme Linked Immuno-Sorbent Assay (ELISA). Results showed that aflatoxin B₁ synthesis was inhibited by 1000 mg l^?1 of L. rugosa essential oil after 8 days of incubation. The effect of the EO on the H⁺-ATPase pumping membrane was also evaluated in the presence of several concentrations of oil (200–2000 mg l^?1) by monitoring glucose-induced acidification of the external medium. L. rugosa essential oil at the concentration of 2000 mg l^?1 completely inhibited the activity of this enzyme. These data suggest that the essential oil of L. rugosa is a fungicidal for A. flavus and its possible cellular target include the H⁺-ATPase.Results obtained in the present study indicate the possibility of exploiting Lippia rugosa essential oil in the fight against strains of A. flavus responsible for biodeterioration of stored foods products.     

改性秸秆纤维油气层保护暂堵剂室内评价试验

以膨化生产得到的形状不规则和长短级配的多种裂解改性秸秆纤维为主要原料,配合刚性粒子、变形粒子等开发出了钻井液用油气层保护暂堵剂(YQKD).室内评价试验结果表明:在基浆中加入3%的 YQKD,即能对地层进行有效封堵;在饱和盐水钻井液中加入YQKD后,动、静态滤失速率降低,泥饼增厚,最大反排压力降低,静态渗透率恢复值由66.7%提高到77.7%,动态渗透率恢复值由50.2%上升为69.1%;随着YQKD加量增至8%,动、静态渗透率恢复值分别达到84.4%和89.8%.YQKD是一种集防漏、堵漏、屏蔽暂堵为一体的"绿色环保"新型油气层堵漏保护材料,在石油、天然气钻探中具有广阔的应用前景.     

An ionic liquid as a potential multifunctional lubricating oil additive

Abstract

Homopolymer of decyl acrylate was synthesized and blended with phosphonium based ionic liquid and their characterisation was carried out by spectral method (NMR, IR), thermogravimetric analysis and gel permeation chromatography (GPC). Performance of these blends were evaluated by standard ASTM method in base oil which clearly indicates that the blend effectively act as anti-wear agent and also pour point depressants and viscosity modifiers. A comparison of their performances with homopolymer has also been evaluated and reported.     

First report: Penicillium adametzioides,a potential biocontrol agent for ochratoxin-producing fungus in grapes,resulting from natural product pre-harvest treatment

Ochratoxin A (OTA) is a secondary metabolite produced mainly by Aspergillus section Nigri (Aspergillus carbonarius is the most relevant strain in the Mediterranean region with a group 2B carcinogenic effect in humans. In vivo experiments were conducted in southern France involving applying pre-harvest Stifénia^® (elicitor), Scala^® (chemical fungicide) and two other control treatments [not contaminated by A. carbonarius (OTA-PF) and not treated and artificially contaminated by OTA-PF but not treated]. The Stifénia^® and Scala^® treatments significantly reduced the OTA juice contamination so that it was under the authorised uptake OTA limit. Stifénia^® highly affected the grape fungal ecosystem with new non-Aspergillus strains isolated from grape stems and juices. In vitro antagonistic tests were performed with Stifénia^® non-Aspergillus isolates (n = 10). Three antagonistic tests were applied using different distances (3 and 5 cm in between the two microorganisms) with two different inoculation times (at the same time and with three day intervals in between). Certain strains had a positive mycelial growth effect on A. carbonarius colonies, such as Penicillium spp. and Fusarium sp. Other strains displayed a reduction effect on OTA production of OTA-PF, such as Penicillium spp. (J2, J3). Penicillium adametzioides (S3) and Penicillium expansum (J1) (at certain stages) reduced the OTA production and mycelial growth. P. expansum was excluded as a bio-control agent because of its mycotoxin production ability. The higher challenge distance between certain strains of P. adametzioides (S3) and other Penicillium strains (as J1, J2, J3 and J4; at three and seven days) reduced the secretion of OTA by OTA-PF. This OTA production reduction could possibly prevent OTA contamination prevention in the case of epidemic favourable conditions by reducing the OTA produced in grape post-harvest products (i.e., juice). This could be accomplished by applying as the elicitor one of the tested fungi with an antagonistic effect on OTA production, such as P. adametzioides (at 10 days). Certain strains, such as P. adametzioides (S3) and J2 (P. spp.) should be further investigated to determine the details of the underlying mechanism of their OTA reduction and their ecosystem effects in cases of in vivo application.     

Effectiveness of a phage cocktail as a biocontrol agent against L. monocytogenes biofilms

Listeria monocytogenes can persist and form biofilms in a food environment which are difficult to eradicate because biofilms are inherently resistant to a variety of antimicrobial treatments. Therefore, alternative approaches such as bacteriophages have been suggested as a promising biocontrol agent against biofilms. The aim of this study was to evaluate the efficacy of a cocktail bacteriophage product (ListShield™) against L. monocytogenes biofilms. These biofilms were established on lettuce, stainless steel, rubber, and a MBEC biofilm device and exposed to the ListShield™ phage preparation (1 × 10⁸ PFU/mL) for 2 h. ListShield™ had sufficient potency to significantly reduce the biofilm (P < 0.05) in all cases. Biofilm reduction achieved after ListShield™ treatment on the stainless steel coupon was 1.9–2.4 log CFU/cm² and on the rubber surface approximately 1.0 log CFU/cm². Phage application on lettuce inactivated biofilm bacteria up to 0.7 log CFU/cm². These results suggest that bacteriophage preparation ListShield™ is an effective tool for the inactivation of L. monocytogenes biofilms in the food industry.     

Effects of phenyllactic acid as sanitizing agent for inactivation of Listeria monocytogenes biofilms

3-Phenyllactic acid (PLA) has been reported as an antimicrobial compound with broad-spectrum activity, and it can be produced by food-grade microorganisms, including a wide range of lactic acid bacteria species. In this study, the efficacy of PLA to inactivate Listeria monocytogenes planktonic cells and biofilms was determined and compared with the killing effects of lactic acid (LA), and levulinic acid (LVA) with sodium dodecyl sulfate (SDS). L. monocytogenes biofilms of different maturities, i.e., 37 °C for 3 and 7 d and 15 °C for 4 and 7 d, were produced on 24-well flat-bottom polystyrene plates and treated with PLA (0.25%–3%), LA (1% and 3%), and 3% LVA plus 2% SDS for 5, 10, 30, 60 min, respectively. The results of pure culture assays revealed that 1% PLA reduced the population of L. monocytogenes by 7 log CFU/ml within 1 min. The biofilms assays revealed that L. monocytogenes biofilms could be inactivated to different degrees by the sanitizer treatments. The killing effect of PLA treatment was increased as exposure time and PLA concentrations were increased. The sanitizers of 3% PLA and 1% PLA effectively inactivated the early mature biofilm after a 5-min treatment, whereas 3% PLA was better than all the other sanitizers, including 1% PLA, 3% LA, 3% LVA and 2% SDS for inactivation of the late mature biofilm after a 5-min treatment. Confocal laser scanning microscopy analysis revealed that bacterial cell damages in the biofilm were enhanced as the PLA concentrations and exposure times were increased. These results suggested that PLA was effective in inactivating L. monocytogenes and its biofilm, even for the late mature biofilm.     

一种解卡液评价仪简介

为了对解卡液解卡能力做出正确的评价,在考察井下实际解卡情况的基础上研制出一种解卡液评价仪。此仪器用底盘和室体分别摸拟钻柱和井眼,在底盘周围形成6mm厚的滤饼,对井下解卡情况进行模拟。试验证明,该仪器能较好地模拟井下解卡情况而对解卡液进行评价,具有较好的精度和一定的准确度。此外,该仪器结构简单,使用方便且价格便宜,便于推广应用。