Solid-state NMR characterization of tri-ethyleneglycol grafted polyisocyanopeptides.

In aqueous media, ethylene glycol substituted polyisocyanopeptides (PICPs) change their state (undergo a sol-to-gel transition) as a response to temperature. This makes them promising materials for various biomedical applications, for instance, for controlled drug release and non-damaging wound dressing. To utilize PICP in biomedical applications, understanding of the origin of the gelation process is needed, but this is experimentally difficult because of the notoriously low gelator concentration in combination with the slow polymer dynamics in the sample. This paper describes a detailed characterization of the dried state of PICPs by solid-state NMR measurements. Both the (13) C and the (1) H NMR resonances were assigned using a combination of 1D cross-polarization magic angle spinning, 2D (13) C-(1) H heteronuclear correlation spectra and (1) H-(1) H single quantum-double quantum experiments. In addition, the chemical groups involved in dipolar interaction with each other were used to discuss the dynamics and spatial conformation of the polymer. In contrast to other PICP polymers, two resonances for the backbone carbon are observed, which are present in equal amounts. The possible origin of these resonances is discussed in the last section of this work. The data obtained during the current studies will be further used in elucidating mechanisms of the bundling and gelation. A comprehensive picture will make it possible to tailor polymer properties to meet specific needs in different applications. Copyright © 2015 John Wiley & Sons, Ltd.

Powdery Mildew Outbreaks caused by Podosphaera macularis on Hop Cultivars Possessing the Resistance Gene R6 in the Pacific Northwestern United States.

Resistant cultivars of hop (Humulus lupulus) have been grown, with the aim of helping to manage powdery mildew in the Pacific Northwest since the first report of the disease in the field in 1997 (4). A major objective of many breeding programs is development of resistance to powdery mildew, and this has generally been achieved by single resistance genes (qualitative resistance). One such gene, R6 (3), has been utilized extensively in new cultivars and has prevented epidemics of the disease in those cultivars across the Pacific Northwestern United States for approximately 15 years. In 2011, a grower in Washington State reported outbreaks of powdery mildew on cv. Apollo, which is thought to possess powdery mildew resistance derived from R6. Fungicides and cultural control measures were applied, and the grower reported no substantial crop damage from the disease. During the winter of 2012, the same grower planted rhizomes of cv. Apollo in a greenhouse in the Yakima Valley of Washington State and later found the plants to be affected by powdery mildew. Affected leaves from plants of cvs. Apollo, Newport, and Nugget (all reported [3] or assumed to possess R6 based on pedigree) grown in the same greenhouse were later provided to the authors. Conidia obtained from each affected plants were transferred to plants of the highly susceptible cv. Symphony, which is not known to contain any resistance genes. After 10 to 14 days of incubation, resultant conidia from each cultivar above (total of three isolates) were transferred to greenhouse grown plants of cvs. Nugget and Symphony and incubated at 18°C. Within 7 days, all three isolates produced powdery mildew colonies characteristic of P. macularis (2) on both cultivars. Cleistothecia did not develop in any colonies. In addition, Nugget and Symphony plants were inoculated with a field population of P. macularis originating from cultivars lacking R6 in Oregon. These inoculations on Nugget did not develop powdery mildew whereas Symphony plants did. Non-inoculated controls remained free of powdery mildew. Results were identical in two additional experiments. The sequence of the mating type idiomorph, MAT1-1, was obtained to confirm identity of the pathogen as P. macularis as described previously (1). The sequences were identical among the three isolates obtained from the greenhouse in Washington and isolates of P. macularis obtained previously from Oregon and Washington. MAT1-2 idiomorph was not detected in the isolates collected. While R6-virulent strains have been detected previously in race characterization experiments, these strains have not caused widespread epidemics of powdery mildew. The increasing prevalence of virulent strains of P. macularis and outbreaks of powdery mildew on formerly resistant cultivars necessitates changes in breeding strategies and disease management efforts to minimize damage resulting from the disease. The distribution of virulent strains of the pathogen and susceptibility of formerly resistance cultivars to powdery mildew are currently under investigation. References: (1) B. Asalfet et al. Phytopathology 103:717, 2013. (2) R. Bélanger et al. The Powdery Mildews: a Comprehensive Treatise. APS Press, St. Paul, MN, 2002. (3) P. Darby. Brew Hist. 121:94, 2005. (4) C. Ocamb et al. Plant Dis. 83:1072, 1999.

The influence of thermochemical treatments on the lignocellulosic structure of wheat straw as studied by natural abundance 13C NMR.

The effects of thermochemical treatments (aquathermolysis, pyrolysis, and combinations thereof) on the lignocellulosic structure and composition of wheat straw were studied with (13)C and (1)H solid state NMR spectroscopy and proton T1ρ relaxation measurements. Results show that aquathermolysis removes hemicellulose, acetyl groups, and ash minerals. As a result, the susceptibility of lignocellulose to pyrolysis is reduced most likely due to the removal of catalytically active salts, although recondensation of lignin during aquathermolysis treatment can also play a role. In contrast to pyrolysis of wheat straw, pyrolysis of aquathermolysed wheat straw leaves traces of cellulose in the char as well as more intense lignin methoxy peaks. Finally, it was found that both pyrolysis chars contain aliphatic chains, which were attributed to the presence of cutin or cutin-like materials, a macromolecule that covers the aerial surface of plants, not soluble in water and seemingly stable under the pyrolysis conditions applied.

The electronic structure and ionic diffusion of nanoscale LiTiO2 anatase.

Upon lithium insertion in the pristine TiO2 anatase phase the theoretical maximum of LiTiO2 can be reached in crystallite sizes less than approximately 10 nm, whereas bulk compositions appear limited to Li(x) approximately 0.6TiO2 at room temperature. Both X-ray absorption spectroscopy (XAS) and ab initio calculations have been applied to probe the electronic structure of the newly formed LiTiO2 phase. These results indicate that a large majority of the Li-2s electrons reside at the Ti-3d(t2g)/4s hybridized site. About 10% of these electrons are transferred to non-localized states which makes this compound a good electronic conductor. Ionic conductivity is probed by nuclear magnetic resonance (NMR) relaxation experiments indicating relatively small hopping rates between the Li-ion sites in LiTiO2. Formation of the poor ionic-conducting LiTiO2 at the surface of the particles explains why micro-anatase Li(x)TiO2 is not able to reach the theoretical maximum capacity at room temperature, and why this theoretical maximum capacity reached in nano-sized materials cannot be (dis)charged at high rates.

High-resolution liquid- and solid-state nuclear magnetic resonance of nanoliter sample volumes using microcoil detectors.

The predominant means to detect nuclear magnetic resonance (NMR) is to monitor the voltage induced in a radiofrequency coil by the precessing magnetization. To address the sensitivity of NMR for mass-limited samples it is worthwhile to miniaturize this detector coil. Although making smaller coils seems a trivial step, the challenges in the design of microcoil probeheads are to get the highest possible sensitivity while maintaining high resolution and keeping the versatility to apply all known NMR experiments. This means that the coils have to be optimized for a given sample geometry, circuit losses should be avoided, susceptibility broadening due to probe materials has to be minimized, and finally the B(1)-fields generated by the rf coils should be homogeneous over the sample volume. This contribution compares three designs that have been miniaturized for NMR detection: solenoid coils, flat helical coils, and the novel stripline and microslot designs. So far most emphasis in microcoil research was in liquid-state NMR. This contribution gives an overview of the state of the art of microcoil solid-state NMR by reviewing literature data and showing the latest results in the development of static and micro magic angle spinning (microMAS) solenoid-based probeheads. Besides their mass sensitivity, microcoils can also generate tremendously high rf fields which are very useful in various solid-state NMR experiments. The benefits of the stripline geometry for studying thin films are shown. This geometry also proves to be a superior solution for microfluidic NMR implementations in terms of sensitivity and resolution.

Homonuclear correlation experiments for quadrupolar nuclei, spinning away from the magic angle.

We present a set of homonuclear correlation experiments for half-integer quadrupolar spins in solids. In all these exchange-type experiments, the dipolar interaction is retained during the mixing time by spinning the sample at angles other than the "regular magic angle" (54.7 degrees celsius). The second-order quadrupolar interaction is averaged by different strategies for the different experiments. The multiple-quantum off magic angle spinning (MQOMAS) exchange experiment is essentially a regular MQMAS experiment where the quadrupolar interaction is averaged by combining magic angle spinning with a multiple- to single-quantum correlation scheme. The sample is spun at the magic angle at all times except during the mixing time which is added to establish homonuclear correlation. In the multiple-quantum P4 magic angle spinning (MQP4MAS) exchange experiment, the sample is spun at one of the angles at which the fourth-order Legendre polynomial vanishes (P4 magic angle), the remaining second-order quadrupolar interaction now governed by a second-rank tensor is refocussed by the multiple to single-quantum correlation scheme. In the dynamic angle spinning (DAS) exchange experiment, the second-order quadrupolar interaction is averaged by correlating the evolution from two complementary angles. These experiments are demonstrated and compared, in view of their specific advantages and disadvantages, for 23Na in the model compound Na2SO3.

Sonochemical polymerization of diphenylmethane.

Sonolysis of diphenylmethane (DPhM) has been studied under the effect of 20 kHz ultrasound (absorbed acoustic power 0.45 W/ml, surface area of sonotrode 1 cm(2), volume of sonicated solution 100 ml) under argon at 60 degrees C. The solid product of the sonolysis was characterized by elemental analysis, FTIR, 13C MAS NMR, TGA/DSC, XRD and TEM techniques. It was found that the sonolysis of DPhM causes formation of the polymer with the composition similar to crosslinked polystyrene. Assumed mechanism of DPhM sonolysis consists of DPhM molecules dissociation inside the cavitating bubble. Secondary radical scavenging and radical recombination processes yields the sonopolymer in the liquid phase. The breakdown of the aromatic ring during DPhM sonolysis confirms that a very high temperature established in the cavitating bubble.

Observation of hydroxyl groups by 17O solid-state multiple quantum MAS NMR in sol-gel-produced silica.

17O NMR parameters (CQ, eta, delta(iso) and T1) are reported for both Si-O-Si and Si-OH fragments within a silica gel. The Si-OH units have a wide spread of parameters but are typically characterised by a very short T1 (approximately 0.1 ms) and CQ < 200 kHz. These observations have extremely important implications for the quantification of such units in these gels and related glassy materials by 17O NMR. In light of these observations, the 17O NMR experiments have been optimised and a distinct resonance from the OH group is observed in 1D static and magic angle spinning (MAS) NMR measurements as well in the multiple quantum (MQ) experiment.

The effect of high-efficiency particulate air respirator design on occupational health: a pilot study balancing risks in the real world.

OBJECTIVES: To quantify specific factors believed to increase healthcare worker (HCW) risk for contaminated sharps injuries (eg, visibility, communication, and range of motion); to quantify the degree to which respirators of various designs impacted those same factors; and to assess HCW opinions about the suitability of selected respirators with respect to patient care and user compliance criteria. DESIGN: Sharps injury data from seven hospitals were analyzed to determine the potential contribution of visibility, communication, and range of motion to reported injuries. Healthcare workers representing various clinical specialties and physical characteristics were examined at baseline and while wearing five different respirators to quantify the impact of respirator design on visibility, communication, and range of motion. Healthcare workers were interviewed and completed a survey assessing each respirator. SETTING: Hospital and ambulatory-care settings. PARTICIPANTS: Population-based and convenience sample. RESULTS: Communication, visibility, and range of motion were found to affect contaminated sharps injuries significantly. Selected high-efficiency particulate air (HEPA) respirators were found to have a negative impact on each of these variables. Healthcare workers involved in the study also reported compliance criteria problems with selected HEPA respirators, which may effect implementation of respiratory precautions adversely. CONCLUSION: Current HEPA respirators, because of their design, potentially increase the risk of bloodborne pathogen exposure through sharps injuries. We conclude that mandating respirators without regard to the potential impact of their design to the sharps injuries may be counterproductive to HCW safety, because they may increase, rather than decrease, overall occupational risk to HCWs.

Measurement of surface tension in biological fluids by a pulsating capillary technique.

Ever since the discovery of the antiatelectatic function of the pulmonary surfactant, the measurement of surface tension (ST) has been of increasing importance in respiration physiology and clinical research. For the determination of ST, the elevation of the level of a fluid artificially pulsated in a capillary glass tube was monitored, and ST was calculated with the digitalized video-computerized picture analysis program Surftens. The biological relevance of the method is given by the Gibbs-Thomson principle, according to which surface-active lipids stream towards the surface by an adsorptive process; on pulsation of the fluid in a capillary glass tube, therefore, ST is gradually decreased to a minimal value. ST values of 60 amniotic fluid samples collected from pregnancies with different gestation times were determined. A multiple regression analysis of the results, including other parameters (total protein content, total lipid content, phospholipid content and microviscosity), indicated that this method may enhance the precision of the determination of gestation time. Precision analysis of various samples proved that this technique gives well-reproducible results under the given standardized conditions. The main field of application of the method may be in clinical practice and in studies on as yet inadequately known factors affecting the ST of biological fluids.

Spin density description of rotational-echo double-resonance, transferred-echo double-resonance and two-dimensional transferred-echo double-resonance solid state nuclear magnetic resonance.

The spin density matrix formalism has been applied to rotational-echo double-resonance (REDOR), transferred-echo double-resonance (TEDOR) and two-dimensional (2D) TEDOR experiments in order to obtain an expression for the signal intensities. TEDOR spectra of 15N-labeled glycine were measured with different dipolar evolution times. 2D-TEDOR spectra were measured of doubly labeled glycine-2-13C, 15N and of 15N-labeled glycine. Both the TEDOR and the 2D-TEDOR spectra were readily obtained although the 2D-TEDOR experiment on 15N-labeled glycine used a lot of machine time. Even though the 15N-1-13C dipolar coupling is relatively small (200 Hz), the 1-C resonance can still be observed.

The determination of the average 27Al-31P distance in aluminophosphate molecular sieves with SEDOR NMR.

The average 27Al-31P distances in an aluminophosphate, AlPO4-5, and in a silicoaluminophosphate, SAPO-11, were determined by using Spin Echo DOuble Resonance (SEDOR). A calculated SEDOR curve was fitted to the data in order to obtain the dipolar coupling constant. The tetrahedral surrounding of 27Al by four 31P atoms in the second coordination sphere was taken into account in the calculation of the theoretical SEDOR curve. The average 27Al-31P distances obtained by using this technique proved to be in good agreement with X-ray diffraction data.

[Hypoxic myoglobinemia in severe neonatal disorders of adaptation to extrauterine life]. / Hypoxiás myoglobinaemia vizsgálata az újszülöttek extrauterin élethez való súlyos adaptációs zavaraiban.

In two series of newborns needing intensive care the presence, the degree and the prognostic value of myoglobinaemia was examined. In series I. of hypoxic newborns the myoglobinaemia was present even in infants requiring less than 60% O2 therapy. The serum myoglobin value was significantly higher in cases needing oxygen therapy over 60% oxygen. This was most pronounced in the critically severe and progressive cases. In series II. of 34 consecutive cases of hypoxic newborns exceeding 7 nM/l proved to have a prognostic value indicating critically severe course or fatal outcome of the disease. The myoglobinaemia observed in the present study may explain the effectivity of the peritoneal dialysis therapy introduced previously by us in severe hypoxic newborns. This possibility was supported by further observations on the transperitoneal passage of myoglobin in 4 renal hilus ligated and peritoneally dialyzed newborn piglets. In conclusion, early detection of the elevated myoglobinaemia in severely hypoxic newborns has a definite prognostic value and its degree can be used in the indication of peritoneal dialysis.

Beta-adrenergic receptors of lymphocytes in children with allergic respiratory diseases.

The beta-adrenergic receptor binding sites on peripheral lymphocytes in children with bronchial asthma (n = 16) and seasonal allergic rhinitis (n = 8) were examined in comparison with normal controls (n = 18) by means of 124I-cyanopindolol. The number of beta-adrenergic receptors was significantly lower in the asthmatic group (858 +/- 460/lymphocyte) than in the controls (1564 +/- 983/lymphocyte). The value (1891 +/- 1502/lymphocyte in children with allergic rhinitis was slightly higher than that in healthy controls. Of the 24 patients suffering from allergic diseases of the lower or upper airways, the bronchial histamine provocation test was performed in 21; 16 gave positive results, while 5 were negative. No difference in beta-adrenergic receptor count was found between the histamine-positive and negative patients. Neither was there any correlation between the number of beta-adrenergic receptors and the high (16/24) and low (8/24) serum IgE concentrations found in allergic patients. The significant decrease in beta-adrenergic receptor count in asthmatic children lends support to Szentiványi's concept. Further qualitative and quantitative analysis of lymphocyte beta-adrenergic receptors may provide an individual approach to the treatment of bronchial asthma with beta-sympathomimetic drugs.

Effects of dexamethasone on brain edema induced by kainic acid seizures.

The histopathological alterations developing in the hippocampus, piriform cortex and thalamus of the rat brain, the blood-brain barrier damage, and the effects of dexamethasone pretreatment on the brain edema were investigated 4 h following intraperitoneal kainic acid administration. The most pronounced Evans Blue extravasation accompanied by increases in the water and sodium contents and a decrease in the potassium content, were observed in the thalamus. Dexamethasone, injected in a dose of 5 mg/kg 2 h before kainic acid administration, reduced considerably the vasogenic edema and neuronal damage in the thalamus, but the cytotoxic edema of the hippocampus and piriform cortex remained unaltered. Kainic acid-induced seizures lead to the development of vasogenic brain edema mainly in the thalamus, as well as to cytotoxic edema in the hippocampus and piriform cortex. The vasogenic edema seems to contribute to the cell damage in the thalamus. Dexamethasone reduces the vasogenic edema and cell damage in the thalamus, possibly by inducing the synthesis of certain protein(s) with antiphospholipase A2 activity.

Cerebroprotective effect of dexamethasone by increasing the tolerance to hypoxia and preventing brain oedema in newborn piglets with experimental pneumothorax.

The effect of dexamethasone (DXM) pretreatment in newborn piglets with experimental pneumothorax (EPT) was studied. Neither low DXM doses nor those administered 1 or 2 h prior to the induction of EPT were found to be effective against its course. In contrast, 5 mg/kg of body wt. of DXM given subcutaneously 4 h prior to EPT improved significantly both the tolerance and laboratory data of the animals. The extent of brain oedema, measured 4 h after recovery, was also considerably lowered. Actinomycin D pretreatment prevented almost completely the beneficial effect offered by DXM suggesting the involvement of newly synthesized protein(s) in the cerebroprotective effect of DXM.