Polyurethanes based on 2,2‐Dinitropropane‐1,3‐diol and 2,2‐bis(azidomethyl)propane‐1,3‐diol as potential energetic binders

On the base of 2,2‐bis(azidomethyl)propane‐1,3‐diol (BAMP) and 2,2‐dinitropropane‐1,3‐diol (DNPD) four different polyurethanes were synthesized in a polyaddition reaction using hexamethylene diisocyanate (HMDI) and diisocyanato ethane (DIE). The obtained prepolymers were mainly characterized using vibrational spectroscopy (IR) and elemental analysis. For determination of low and high temperature behavior, differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA) were used. Investigations concerning friction and impact sensitivities were carried out using a BAM drop hammer and friction tester. The energetic properties of the polymers were determined using bomb calorimetric measurements and calculated with the EXPLO5 V6.02 computer code. The obtained values were compared with the glycidyl azide polymer (GAP). The compounds turned out to be insensitive toward friction (>360 N) and less sensitive toward impact (40 J). The good physical stabilities, along with their sufficient thermal stability (170–210 °C) and moderate energetic properties renders these polymers into potential compounds for applications as binders in energetic formul;ations. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43991.     

Discriminative Response to Animal, But Not Plant, Chemicals by an Insectivorous, Actively Foraging Lizard, Scincella lateralis, and Differential Response to Surface and Internal Prey Cues

Responses by the insectivorous, actively foraging scincid lizard, Scincella lateralis, to chemical cues from a plant food favored by herbivorous lizards, its ability to discriminate prey chemicals from control substances, and its relative response to internal and surface prey chemicals were studied experimentally. We presented chemical cues to the lizards on cotton swabs and recorded their tongue-flicks and biting attacks on the swabs. The lizards exhibited significantly greater tongue-flick rates and biting frequencies to prey surface cues than to plant surface chemicals from romaine lettuce, diluted cologne (pungency control), and deionized water. Responses to the plant stimuli did not differ from those to the two control stimuli, in contrast with strong responses to the same plant cues by herbivores. This finding provides the first information suggesting that chemosensory response may be adapted to diet, with responsiveness to plant stimuli evolving de novo in herbivores. Biting and tongue-flicking responses were significantly greater to cricket chemicals than to all other stimuli, among which there were no differences. Thus, the lizards are capable of prey chemical discrimination, which may be ubiquitous among actively foraging lizards. The lizards exhibited more frequent biting and higher tongue-flick rates to internal than surface prey chemicals. Although different methods of stimulus preparation are appropriate for different purposes, we conclude that prey surface chemicals available to foraging lizards are most desirable for studies bearing on location and identification of prey.     

Potential Energetic Plasticizers on the Basis of 2,2‐Dinitropropane‐1,3‐diol and 2,2‐Bis(azidomethyl)propane‐1,3‐diol

Different carboxylic acid derivatives of 2,2‐dinitropropane‐1,3‐diol (DNPD) and 2,2‐bis(azidomethyl)propane‐1,3‐diol (BAMP) were synthesized to investigate their suitability as energetic plasticizers. The syntheses were carried out using acyl chlorides of acetic, propionic, and butyric acid. The obtained products were characterized by elemental analysis, NMR, and IR spectroscopy. The energetic properties of the synthesized compounds were calculated on the basis of the computed heats of formation at the CBS‐4M level of theory using the EXPLO5 version 6.02 computer code. Investigations of physical stabilities were carried out using BAM drop hammer and friction tester. Low and high temperature behavior was determined by differential scanning calorimetry (DSC). The energetic and physical properties of the synthesized compounds were compared to the literature known energetic plasticizers N‐butyl nitratoethylnitramine (BuNENA) and diethylene glycol bis(azidoacetate) ester (DEGBAA). For analyzing the plasticizing abilities, mixtures of glycidyl azide polymer (GAP) and poly(3‐nitratomethyl‐3‐methyloxetan) (polyNIMMO) were prepared with both propionyl based compounds in different ratios and investigated regarding their glass transition temperatures and viscosity. Both compounds showed plasticizing effects in the range of BuNENA.     

A pH-dependent conformational change in the B-subunit pentamer of Escherichia coli heat-labile enterotoxin: structural basis and possible functional role for a conserved feature of the AB5 toxin family

The non-covalently associated B-subunit moieties of AB5 toxins, such as cholera toxin and related diarrheagenic enterotoxins, exhibit exceptional pH stability and remain pentameric at pH values as low as 2.0. Here, we investigate the structural basis of a pH-dependent conformational change which occurs within the B5 structure of Escherichia coli heat-labile enterotoxin (EtxB) at around pH 5.0. The use of far-UV CD and fluorescence spectroscopy showed that EtxB pentamers undergo a fully reversible pH-dependent conformational change with a pKa of 4.9 +/- 0.1 (R2 = 0.999) or 5.13 +/- 0.01 (R2 = 0.999), respectively. This renders the pentamer susceptible to SDS-mediated disassembly and decreases its thermal stability by 18 degrees C. A comparison of the pH-dependence of the structural change in EtxB5, with that of a mutant containing a Ser substitution at His 57, revealed that the pKa of the conformational change was shifted from ca. 5.1 to 4.4. This finding suggests that protonation of the imidazole side chain of His 57 might facilitate disruption of a spatially adjacent salt bridge, located between Glu 51 and Lys 91 in each B-subunit, thus triggering the conformational change in the pentameric structure. The pH-dependent conformational change was found to be inhibited when B-subunits bound to monosialoganglioside, GMI; and to have no effect on the stability of interaction between A- and B-subunits within the AB5 complex. This suggests that the conformational change is unlikely to have a direct involvement in toxicity. Conservation of the pH-dependent conformational change in the AB5 toxin family, combined with the potential exposure of the hydrophobic core of beta-barrel in the monomeric units, leads to the proposal that the conformational change may be the common feature that ensures the secretion of these proteins from the Vibrionaceae.     

Patients' action during their cardiac event: qualitative study exploring differences and modifiable factors

OBJECTIVES: To explore the circumstances and factors that explain variations in response to a cardiac event and to identify potentially modifiable factors. DESIGN: Qualitative analysis of semistructured, face to face interviews with patients admitted to two district hospitals for a cardiac event and with other people present at the time of the event. Patients were divided into three groups according to the length of delay between onset of symptoms and calling for medical help. SUBJECTS: 43 patients and 21 other people present at the time of the cardiac event. Patients were divided into three groups according to the length of time between onset of symptoms and seeking medical help: non-delayers (< 4 h; n = 21), delayers (4-12 h; n = 12), and extended delayers (> 12 h; n = 10). MAIN OUTCOME MEASURES: Decision making process, strategies for dealing with symptoms, and perception of risk and of heart attacks before the event according to delay in seeking help. RESULTS: The illness and help seeking behaviour of informants had several components, including warning, interpretation, preliminary action, re-evaluation, and final action stages. The length of each stage was variable and depended on the extent to which informants mobilised and integrated resources into a strategy to bring their symptoms under control. There were obvious differences in informants' knowledge of the symptoms that they associated with a heart attack before the event. Non-delayers described a wider range of symptoms before their heart attack and twice as many (13) considered themselves to be potentially at risk of a heart attack compared with the other two groups. For most informants the heart attack differed considerably from their concept of a heart attack. CONCLUSION: The most critical factor influencing the time between onset of symptoms and calling for professional medical help is that patients and others recognise their symptoms as cardiac in origin. This study suggests that various points of intervention in the decision making process could assist symptom recognition and therefore faster access to effective treatment.     

Current trends in modern orthokeratology

This article reviews current knowledge on the effect of testicular germ cell cancer (TGCC) on gonadal function and of the cancer treatment on spermatogenesis and Leydig cell function. It seems likely that development of TGCC shares common etiological factors with development other types of testicular dysfunction. This suggestion is supported by the observation that men with various types of gonadal dysfunction such as testicular dysgenesis, androgen insensitivity syndrome, and cryptorchidism have increased risk of testicular cancer. Epidemiological and clinical data indicate common etiology between testicular germ cell cancer and other abnormalities in male reproductive health such as infertility and cryptorchidism. These observations are in agreement with the suggestions of hormonal involvement in the etiology of testicular cancer. It is well documented that testicular cancer is associated with impaired spermatogenic function and some patients have impairment of Leydig's cell function already before orchidectomy. The degree of spermatogenic dysfunction is higher than what can be explained by local tumor effect and by a general cancer effect. These observations are supported by histological investigations, which have shown a high prevalence of abnormalities of spermatogenesis in the contralateral testis in patients with unilateral TGCC. The spermatogenetic function is still severely impaired after orchidectomy and radiotherapy as well as chemotherapy induce further dose-dependent impairment of spermatogenesis. Recovery of spermatogenesis after treatment may be long, in some patients lasting more than 5 years. Sufficient androgen production is seen in the majority of the patients but some patients do suffer from testosterone deficiency. The effect of chemotherapy on Leydig's cell function seems to be dose dependent. Trials on protection of spermatogenetic function against the harmful effects of radiotherapy and chemotherapy by suppression of spermatogenesis has not been successful. The only way to maintain fertility is to limit gonadal exposure to harmful agents. Moreover cryopreservation of semen should be done before treatment. The optimal time for cryopreservation is before orchiectomy at least in some patients. Generally men with TGCC need counselling about their reproductive function, with respect to semen cryopreservation, chance for recovery of spermatogenesis, fertility, and the possibility of need for androgen replacement.     

Aesthetic geometry evolution in a generic interactive evolutionary design framework

An interactive evolutionary design framework is presented which provides a testbed for the development and exploration of a range of visual aesthetic design spaces. A commercial 3D digital content development software package is used to leverage the strength of existing 3D algorithm implementations and familiar interfaces and tools. The domain of non-representational 3D forms sculpted with a series of non-linear deformers is discussed as the primary example. Additional simple problem domains are shown which are being developed to serve as examples for non-programmer artists and designers who are familiar with digital content authoring in Maya. These examples will enable such individuals to rapidly construct their own interactive evolution systems. Matthew Lewis, Ph.D.: He is a researcher at The Advanced Computing Center for the Arts and Design (ACCAD) at The Ohio State University, where he received his M.S. (1993) and Ph.D. (2001) degrees in Computer Science. His research interests include evolutionary design, generative art, and data remapping for artistic performance and installation. Keith Ruston: He is a student at The Ohio State University where he has earned his B.S. in Computer Science & Engineering (2003) and is currently pursuing his M.S. His major field of study is graphics and animation. His career goals include working in the animated film industry and/or computer game development.     

Mediated Martyrs of the Arab Spring: New Media,Civil Religion,and Narrative in Tunisia and Egypt

This article analyzes the emergence of nationalist martyr narratives and their dissemination via new media as forces for social mobilization and political change. Situating them in the religio‐historical contexts of North Africa, we trace martyr narratives in Tunisia and Egypt back to pre‐Islamic periods and compare them to the contemporary stories of Mohamed Bouazizi and Khaled Saeed. This reveals the impact of new media on the region, evident in “virtual reliquaries,” and the role that martyr narratives play as catalysts in social mobilization. The trajectory of the martyr narrative from the traditional religious context to the state‐driven concept of civil religion allows for the political dimension of narratives resident within the religious context to surface in the contemporary discursive moment.