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Engineers make things, make things work, and make things work better and easier. This kind of knowledge is crucial for innovation, and much of the explicit knowledge developed by engineers is embodied in scientific publications. In this paper, we analyze the evolution of publications and citations in Engineering in a middle-income country such as Mexico. Using a database of all Mexican publications in Web of Science from 2004 to 2017, we explore the characteristics of publications that tend to have the greatest impact; this is the highest number of citations. Among the variables studied are the type of collaboration (no collaboration, domestic, bilateral, or multilateral), the number of coauthors and countries, the language of the article, controlling for a coauthor from the USA and the affiliation institution of the Mexican author(s). Our results emphasize the overall importance of joint international efforts and suggest that publications with the highest number of citations are those with multinational collaboration (coauthors from three or more countries), written in English, and when one of the coauthors is from the USA.

Highlights • The incidence of periprosthetic hip infections his just below 2%, and the Enterobacteriaceae are fairly rare, being the cause of infection in 3–6% of cases. • A 76 year old woman with multiple comorbidities underwent surgical implantation of endoprosthesis of the left hip. • Multidisciplinary diagnosis of a rare periprosthetic infection., Introduction The Enterobacter cloacae is a microorganism found in the intestinal flora of the majority of animals, including humans. Primary infections caused by E. cloacae are rare in immunocompetent patients, but are very common in hospital settings in newborns and immunocompromised patients, and can be aggravated by the insurgence of antibiotic resistance. The incidence of periprosthetic hip infections is just below 2%. Case presentation A 76 year old woman with multiple comorbidities underwent surgical implantation of intermediary total hip prosthesis of the left hip, in a different health facility, in February 2014, after the basicervical fracture of the upper femur extremity due to trauma. After an episode of dislocation of the prosthetic implant, in September 2014, she underwent a surgical operation to implant the acetabular component. A month later not in our facility, following a re-hospitalization for the dislocation of the arthroprosthesis, an infection from E. cloacae complex was discovered. After 2 years of chronic infection she came to our attention; the clinical picture featured coxalgia and secreting fistula in the surgical wound. Following a specific antibiotic therapy, carried out intravenously over the course of a month, we decided to intervene removing the left hip arthroprosthesis and placing an antibiotic spacer following the direction deduced from the antibiogram study of August 2016. Conclusion The patient was hospitalized in our facility and 2 months later she underwent another operation to remove the antibiotic spacer and to place a new total hip arthroprosthesis. Multiple swabs showed the complete healing from the infection, which was confirmed a couple of months later.

Introduction: Essential oils have been used since ancient times and are known for their anti-inflammatory, anti-depressive, antiseptic, antifungal and antimicrobial properties. Methodology: in this study the antimicrobial activity of two essential oils from Melaleuca alternifolia and Thymus vulgaris–red thyme geraniol was tested against 16 multidrug-resistant P. aeruginosa strains from infected hip implants as well as the “in vitro” cytotoxic activity on normal human Wong-Kilbourne derivative (WKD) cells. Results: Thymus vulgaris–red thyme geraniol showed lower antimicrobial activity when compared to Melaleuca alternifolia. All tested oils were cytotoxic at concentrations lower than 0.12%. Conclusion: Increase in drug resistance and lack of new antibiotics may encourage the development of natural treatments together with higher concern on environmental issues and natural lifestyle.

The 13C NMR spectra of a carbon nanofoam sample, exhibiting a peak in the ZFC magnetic susceptibility, show a single 13C line at room temperature and a two peak structure at 100 K. The splitting and the NMR shifts are however much too small to be associated with true ferromagnetism as for instance observed in TDAE-C60 below TC. The X-band EPR spectra show the presence of a least three different paramagnetic clusters with ga = 2.0016, gb = 2.0031, gc = 2.0036 and very different electronic spin-lattice relaxation times. In some samples the CW EPR spectra show an additional rather broad and strongly temperature dependent line shifted to lower fields, which is characteristic of ferromagnetic systems. The results thus show an inhomogeneous super-paramagnetic or spin-glass like nature of magnetism in cluster assembled carbon nanofoam rather than homogeneous ferromagnetism.

The temperature dependence of the17O nuclear quadrupole resonance (NQR) frequencies has been measured in commercial trinitrotoluene by highly sensitive nuclear quadrupole double resonance techniques. The14N NQR frequencies have been measured in the same sample for comparison. In contrast to the14N quadrupole coupling constant, the17O quadrupole constant increases with increasing temperature.

The17O and23Na nuclear quadrupole resonance spectra of powdered sodium formate and sodium acetate have been determined at room temperature by proton-17O and proton-23Na double resonance. All17O sites have been found to be chemically equivalent. The nonzero value of the asymmetry parameter of the electric field gradient tensor at the17O site shows that the electron density distribution is not cylindrically symmetric around the C−O bond axis.

The longitudinal relaxation timeT1 and the second momentM2 of1H nuclear magnetic resonance line in a wide temperature range have been measured for acetylcholine chloride. Two different types of the methyl groups reorientation occurred. The first type was the hindered rotation of the methyl group denoted as C(1)H3 about the threefold symmetry axis. The second type was the reorientation of the trimethyl group-N(CH3)3 around the pseudo C3′ axis of C(6)-N(7) bond, which accompanied the standard C3 motion of the methyl group. The Dunn-McDowell model was applied to analyze the dynamics observed.

Proton spin–lattice relaxation, compressive strength, and water tightness measurements have been undertaken in order to study the hydration process and the mechanical properties of Portland cement modified with a calcium sulfoaluminate-based expansive additive (EXPAD). The compression strength of the modified cement was more than 70% higher while water permeability was about 60% smaller than in the unmodified cement. Magnetization–recovery curves analysis allowed for a time-resolved monitoring of both the increase of the internal surface as well as the formation of solid products during the hydration. A significant difference between the hydration kinetics of modified and unmodified cement was observed.

When placed into an external magnetic field inhomogeneous porous structures, like rocks, cement gels, ceramics, etc., exhibit strong local magnetic field gradients (LMFG), which are inherently related with the size, shape, and distribution of their pores. In this paper, we present a method of measuring LMFG in a liquid-filled porous media, provided that the fast exchange model sufficiently describes water motion in the pores, which is based solely on the measurement of the water 1H NMR spin lattice relaxation rates and the knowledge of the unrestricted diffusion coefficient. The method is applied to two hydrating white cement samples with different hydration kinetics, and the results are correlated with the time evolution of the pore structure. It is shown that the measured LMFG have extremely high values, which qualitatively reflect the sharp needlelike morphology of the internal cement gel surface.

The influence of the superplasticizer Sikament 92 on the hydration process of white cement paste and freezing behavior of hardened white cement was investigated by 1H spin-lattice relaxation and Single Point Imaging (SPI) methods. The study shows that this superplasticizer extends the workability of the cement paste by about 5 h and significantly increases the hydration rate when compared with pure sample. The pore structures in hardened cement were studied by MRI and demonstrate that Sikament 92 lowers the porosity and increases resistance to freezing.

Hydrogen based fuel cells are considered to be an important future alternative to fossile based energy sources such as oil, natural gas and coal. For many applications such a hydrogen driven cars, the limiting factor is the weight of the hydrogen fuel storage device which seems to be excessive for hydrogen stored in metals. This is the reason for the search for ultralight hydrogen storage materials such as carbon nanotubes or graphite layers. Here we report on the investigation of the basic mechanism of H-carbonaceous interactions leading to hydrogen storage. The system has an ultra-low density of 2-10 mg/cm 3 and a large surface area 300-400 m 2 /g. Electron diffraction showed the presence of hyperbolic "schwarzite" layers making the system suitable for hydrogen storage. Preliminary proton NMR experiments showed that hydrogen can indeed be reversibly stored in carbon nanofoam at room temperature and that the corresponding proton spin lattice relaxation time T, of the stored hydrogen is 400 ms.

1H nuclear magnetic resonance and atomic force microscopy have been correlated in order to exploit the relation between the microscopic morphological properties and the growth dynamics of cement gels during hydration. Studies in a number of samples with different hydration kinetics show that consideration of percolation, gel surface roughness, and related scaling properties is necessary for a thorough understanding of cement hydration kinetics. It is further shown that, at late hydration times, the hydration rate is highly correlated with the cement gel surface roughness exponent χ. A model based on a random walk on a three-dimensional network of rough micropores is proposed in order to explain this effect.

$^{139}\mathrm{La}$ NMR in a zero external magnetic field has been used as a probe in order to study the Mn spin ordering of ${\mathrm{La}}_{0.5}$${\mathrm{Ca}}_{0.5}$${\mathrm{MnO}}_{3}$. For T${\mathrm{T}}_{\mathrm{c}}$ two different spin configurations are detected, assigned to a ferromagnetic and an antiferromagnetic one, which persist down to the lowest measured temperature T=90nK. Close to ${\mathrm{T}}_{\mathrm{c}}$ strong coherent spin fluctuations are detected that presumably drive the paramagnetic-to-ferromagnetic phase transition. Complementary magnetic and ${\mathrm{Mn}}^{4+}$ electron paramagnetic resonance measurements are in agreement with the NMR results.

Slow random-walk-type motion of the modulation wave in structurally incommensurate systems represents a collective atomic self-diffusion in solids. The diffusion constant D for the thermally induced modulation wave motion has been determined using a technique based on NMR and nuclear quadrupole resonance (NQR) in an inhomogeneous electric-field gradient which varies sinusoidally with space. This technique is generally applicable to solids with a modulated superstructure. It is capable of measuring extremely low D values such as ${10}^{\mathrm{\ensuremath{-}}15}$ ${\mathrm{cm}}^{2}$/s, so that spatial motion is observed on a nanometric scale. The diffusive motion is discussed analytically on a scale small compared to the wavelength of the modulation wave, whereas large-scale diffusion is treated numerically. For small-scale motion, spin-echo decay curves in a NMR/NQR experiment show an exponential decay with the exponent proportional to the cube of time and the decay strongly varies over the incommensurate spectrum. For large-scale motion, the spin-echo decay is less strong and the variation over the spectrum vanishes. The diffusion constant has been determined experimentally in ${\mathrm{Rb}}_{2}$${\mathrm{ZnCl}}_{4}$ by $^{35}\mathrm{Cl}$ NQR and in ${\mathrm{K}}_{2}$${\mathrm{SeO}}_{4}$ by $^{39}\mathrm{K}$ NMR. In both cases, D behaves critically in the vicinity of the para-to-incommensurate transition and rapidly decreases on going deeper into the incommensurate phase. This can be explained by the mechanism of thermally induced depinning of the modulation wave at the impurity pinning centers.

The temperature dependence of the proton NMR spectra of bitumen samples of different origin and quality has been measured between 400 K and 80 K. Whereas the linewidths of different samples are essentially identical above 340 K and below 240 K, there is a significant difference in the linewidth transition region around room temperature. The results show that it is possible to discriminate between bitumen samples of different composition and quality by simply measuring the proton NMR linewidth at room temperature.

The solidification of synthetic white cement is monitored by nuclear magnetic resonance. Proton signals in several different environments are resolved and the time evolution of their dynamics and relative numbers is presented. The amounts of liquid water (the water which has not yet entered the solid structure to become crystalline water) and Ca(OH)2 crystallites are monitored precisely during hydration. The technique gives a quantitative insight into the hydration process as well as the growth (and decay) pattern of various cement paste components.

Two-dimensional zero-field nutation NQR spectroscopy enables one to determine the quadrupole coupling constant and the asymmetry parameter in a single experiment on powder samples. The method has been originally developed for the conditions which apply to narrow-line solids so that the nutation frequency is much larger than the NQR linewidth. The irradiation must also be on-resonance. In broad-line solids, these conditions are not fulfilled, and consequently the nutation frequency changes over the NQR lineshape with the irradiation offset. The nutation lineshape varies with offset over the NQR spectrum in a complicated way. The rather simple nutation lineshapes, which can be used for the asymmetry parameter η determination, are obtained only in the on-resonance irradiated parts of the NQR spectrum. Even there, the presence of a finite homogeneous linewidth smears and obscures the characteristic nutation lineshapes, which for narrow homogeneous linewidths exhibit singularities and shoulders. In this paper the theoretical description of the off-resonance effects in the 2D nutation NQR spectroscopy is given and the results are compared to the experiment for a broad-line proton glass Rb 0.98 (NH 4 ) 0.02 H 2 AsO 4 at T = 77 K.

1H nuclear magnetic resonance (NMR) is widely used for the study of water kinetics into various porous systems like sandstones, zeolites, clays, and various cementitious materials. In the case of hydrating cement pastes the evolution of the cement structure ultimately leads to a broad pore size distribution, and consequently to a multiexponential magnetization recovery represented in many cases by a Kohlraush–Williams–Watts ‘‘stretched exponential’’ curve. However, it has been proven an extremely difficult task to fully clarify and exploit the information contained in the multiexponential magnetization recovery of cementitious materials. This difficulty is due to the fact that spin‐lattice relaxation times T1 exhibit broad multimodal distributions, which sometimes extend over more than two orders of magnitude. In this work, a numerical routine using a combination of Monte Carlo and Simplex iterations (MCS) is examined which appears to estimate faithfully broad and complex spin‐lattice relaxation time dist...

The effect of alumino-silicate clay on the hydration of cement is examined through the proton spin-lattice relaxation time (T1's) of the water involved in the hydration process. The evolution of these relaxation times was then correlated with the evolution of compressive strength measurements performed on similar samples. An observed difference in the evolution of T1 between a reference sample and the cement composites is tentatively attributed to the different evolution of porosity in the samples. Compressive strength measurements that have been performed on mortar OPC samples with the same clay concentrations indicate that the addition of clay increases the strength of the mortars during the early stages of hydration (10 to 100 hours). Additional preliminary strength measurements on clay/concrete OPC composites show that the addition of clay also leads to in increase of the final (28 day) compressive strength of the composites samples.

The present understanding of the field of proton and deuteron glasses is reviewed and two recent advances in the magnetic resonance investigations of these systems are reported: (i) the determination of the local polarization distribution function, W ( p ), and the Edwards-Anderson order parameter, q EA , in Rb 1− x (NH 4 ) x H 2 AsO 4 in the ‘weak substitutional disorder’ limit by 75 As nuclear quadrupole resonance (NQR) and nuclear magnetic resonance (NMR), and (ii) the direct determination of intra- and inter-H-bond deuteron exchange in Rb 0.68 (ND 4 ) 0.32 D 2 AsO 4 by two-dimensional O-D··O deuteron ‘exchange’ NMR. The results agree with the basic predictions of the random bond-random field Ising pseudo-spin model of deuteron and proton glasses.

A two-dimensional (2D) zero field NQR separation of inhomogeneous and homogeneous lineshapes technique is described. The nuclear spin Hamiltonian for spinsI>1/2 in zero magnetic field consists to a good approximation only of the electric quadrupole term. The 2D separation technique enables a separate spectroscopic observation of a static and a randomly time-fluctuating dynamic part of the quadrupole interaction. The separation is based on the fact that nuclear spin precession under a static quadrupolar Hamiltonian can be time-reversed whereas this can not be achieved under the action of a randomly time-fluctuaing Hamiltonian. The 2D spectrum displays in theω 2-domain the inhomogeneously broadened lineshape, which is a convolution of the inhomogeneous static frequency distribution function and the homogeneous (adiabatic) lineshape. Theω 1-domain shows the pure homogeneous lineshape. A deconvolution of the inhomogeneous lineshape with the homogeneous one yields a pure static inhomogeneous frequency distribution function which is characteristic and theoretically known for many different models of disordered solids like glasses and incommensurate systems. This technique is important in studies where both lineshapes have comparable widths. The 2D NQR separation technique has been applied to75As in a proton glass Rb0.98(NH4)0.02H2AsO4.

The usefullness of MR imaging in the characterization of pheochromocytomas was evaluated in 9 patients with 13 pheochromocytomas and 1 paraganglioma. In two patients the tumors were multiple and in one, extra-adrenal. Two patients conformed to MEN2 syndrome. Adrenal masses were characterized using several parameters: (a) visual inspection of the signal intensities in T1-, T2-, and Gd-DTPA-enhanced T1-weighted images; (b) observed signal intensity and observed signal intensity ratios (adrenal mass/liver, adrenal mass/retroperitoneal fat and adrenal mass/ subcutaneous fat) in the T2-weighted images; (c) calculated T2 relaxation times and calculated T2 relaxation time ratios (adrenal mass/liver, adrenal mass/retroperitoneal fat and adrenal mass/subcutaneous fat) of the adrenal masses. All pheochromocytomas had a T2 relaxation time greater than 82 ms with a maximum value of 134.3 ms. These values were calculated using T2 quantitative analysis methods based on in-house designed mathematical routines (T2-QMRI). The signal intensities of the tumor on T2-weighted spin-echo images were extremely high. As a conclusion of this preliminary report it is postulated that T2 quantitative MRI examination (T2-QMRI) is an accurate method for the diagnosis and characterization of pheochromocytomas because it gives positive diagnostic results whether the pheochromocytoma is secreting or nonfunctioning. It can also detect extra-adrenal pheochromocytomas (paragangliomas). Comparative studies with other adrenal tumors is essential to assess accuracy of this method for characterizing these tumors.

Randomly quenched impurities pin the modulation wave of incommensurate (I) structures and prevent its free motion. However, rapid thermal fluctuations reduce the pinning frequency (or, in the case of structurally incommensurate insulators (SIIS) the phason gap Delta psi ), and they have a significant effect on the spin-lattice relaxation time T1 and the NMR and NQR lineshapes. A T1 and lineshape model is developed for the I phase of SIIS. This model, which includes impurity pinning and thermal fluctuations, is used to explain 35Cl(1) T1 and experimental lineshape data for a pure Rb2ZnCl4 crystal. The results indicate that, while the impurities are of a strong-pinning symmetry-breaking type very close to the paraelectric-to-incommensurate transition temperature TI, thermal fluctuations significantly reduced the impurity-induced pinning.

A theory of spin-lattice relaxation via large-scale fluctuations of the modulation wave in incommensurate systems is developed for the case of impurity pinning. For a simple model used for the description of such fluctuations, the motionally averaged spectrum and the positional dependence of T 1 in the slowmotion regime are calculated and illustrated graphically. In the thermally depinned regime close to the paraelectric-incommensurate transition temperature T I , an anomalous temperature and Larmor-frequency dependence of the spin-lattice relaxation rate T 1 -1 is predicted

The 87Rb 1/2 − 1/2 NMR spectra and spin-lattice relaxation rates T−11 are studied in the high temperature paraelectric phase, the incommensurate phase, the ferroelectric commensurate phase, and the low temperature commensurate phase of Rb2ZnCl4 between 325 and 6 K. The changes in the 87Rb NMR spectra on going into the low temperature commensurate phase are compatible with the proposed crystal structure of this phase, whereas the observed T1 anomaly reflects the condensation of the soft mode inducing this transition. Die 87Rb 1/2 1/2 NMR-Spektren und Spin-Gitter-Relaxationsraten T−11 werden in der paraelektrischen Hochtemperaturphase, der inkommensurablen Phase, der ferroelektrischen kommensurablen Phase und der kommensurablen Tieftemperaturphase von Rb2ZnCl4 zwischen 325 und 6 K untersucht. Die Anderungen im 87Rb-NMR-Spektrum sind beim Ubergang in die kommensurable Tieftemperaturphase kompatibel mit der vorhergesagten Kristallstruktur dieser Phase, wahrend die beobachtete T1-Anomalie die Kondensation der Softmode, die diesen Ubergang induziert, wiedergibt.

High temperature-resolution NQR measurements in an ultra pure Rb2ZnCl4 crystal and a mixed [Rb1-x(NH4)x]2ZnCl4 crystal with a controlled amount of impurities (x = 0.01) verify the existence of a temperature region where the characteristic incommensurate line splitting is averaged out. The results show that for the system with high purity the averaging of the incommensurate splitting is due to large thermal fluctuations. In contrast, for the mixed crystal the added impurities seem to play the predominant role.

The effect of thermal fluctuations and discreteness of the crystal lattice on the pinning of the modulation wave and the phason gap of structurally incommensurate systems is examined. Very close to the paraelectric-to-incommensurate transition temperature ${\mathit{T}}_{\mathit{I}}$, the phason gap is vanishingly small, but at slightly lower temperatures it takes on a nonzero value. Near the lower incommensurate-to-commensurate transition temperature ${\mathit{T}}_{\mathit{C}}$, where floating effects are negligible, the pinning may lead to a ``devil's staircase''-like temperature dependence of the phason gap.

The temperature dependence of the 14N NQR frequencies have been measured in a series of thermochromic and photochromic salicylideneanilines and related compounds using nuclear quadrupole double resonance. The results show that, in agreement with previous measurements, there is a fast exchange between inequivalent sites in the OH…N bond. The energy difference ΔE of the two proton sites was calculated for all the compounds and shows that it depends on their thermochromic behavior which is connected with the structure of the compounds.

A high temperature resolution measurement of the 35Cl spin-lattice relaxation rate T-11 in Rb2ZnCl4 close to the paraelectric-incommensurate transition temperature TI is reported. The results can be explained by the recently developed theory of spin-lattice relaxation via large scale fluctuations of the modulation wave in incommensurate systems. At lower temperatures the conventional theory of relaxation via phason and amplitudon fluctuations applies.

The 35Cl spin-lattice and spin-spin relaxation times T1 and T2 as functions of temperature and impurity concentration were analytically calculated and experimentally verified for the incommen-surate phase of [Rb1-x (NH 4)x]2 ZnCl4 . The results agree with the theoretical predictions for both the amplitude and Goldstone modes of fluctuations.

The temperature dependence of the 14 N and 17 O NQR frequencies has been measured in N-5-chlorosalicylideneaniline with the help of nuclear quadrupole double resonance. The proton—oxygen distance has been determined from the dipolar structure of the 17 O NQR lines. The results show that there is a fast exchange of protons between two inequivalent equilibrium sites in the OH…N hydrogen bond. The energy difference of the two proton sites is 74 meV.

L'approche theorique montre que le temps de relaxation spin-spin se comporte de facon similaire a celui spin-reseau vis-a-vis de la temperature. Les mesures experimentales sont faites sur les phases paraelectrique, incommensurable, et commensurable. Les resultats sont en accord avec les donnees theoriques

Purpose: The purpose of this study was to examine the effect of periarticular injection of hyaluronate into shoulders with supraspinatus tendinosis under echographic guide. Methods and materials: The subjects were 56 patients with clinical, echographic and magnetic resonance diagnosis of supraspinatus tendinosis. They were divided in two groups by random sampling; 28 patients were assigned in SH group (sodium hyaluronate) and 28 patients in SC group (sodium chloride). The test drug was 20 mg sodium hyaluronate (2 ml, Hyalgan ® , Fidia SpA, Abano T., P.M. 500–700.000, 20 mg/2 ml). Results: Preliminary results showed that sodium hyaluronate presented the highest efficacy in the improvement of clinical symptoms and recovery of functional status in patients with supraspinatus tendinosis in fact the mean V.A.S. score (Visual Analogue Scale) at 1 month after the end of the infiltrative cycle was 8.0 in the SC group vs. 2.8 in SH group and these numerical data were substantially unchanged also after 3 and 4 months. Conclusion: Hyaluronate injection under echographic guide should be use not only as a lubricant but also to prevent articular cartilage degeneration and cover and protect the articular cartilage; indeed sodium hyaluronate can decrease inflammatory joint process. © 2007 Elsevier Ireland Ltd. All rights reserved.

Systemic sclerosis (SSc) is characterised by ischemic damage, impaired angiogenesis and skin fibrosis. Tissue kallikrein (t-kallikrein) is involved through kinins in inflammation, vasorelaxation and angiogenesis. T-kallikrein is synthetised by endothelial, smooth muscle, and inflammatory cells and, in skin, also by dark cells of the sweat glands, where it is involved in sweat formation. Our aim was to analyse, by immunohistochemistry and RT-PCR, the expression of t-kallikrein in the skin of patients with different SSc subsets, limited (lSSc) and diffuse (dSSc), and phases, early and advanced. Skin biopsies were taken from 18 SSc patients and 10 controls. Immunohistochemistry was performed on paraffin sections with an antibody against human urinary t-kallikrein. For RT-PCR, cDNA from skin biopsies was amplified using primers specific for human t-kallikrein. In the control skin, dark cells of the secretory units of sweat glands showed immunopositivity for t-kallikrein as well as blood vessels. In the lSSc skin, immunoreactivity was observed only in some glands, with weak staining in the advanced phase. In early lSSc skin, immunoreactivity was observed in microvessel walls and in the inflammatory infiltrate. In dSSc skin, dark cells of the glandular fundus units, and the few remaining vessels showed scarcity (early phase) or lack (advanced phase) of immunoreactivity for t-kallikrein. RT-PCR confirmed a decrease of t-kallikrein mRNA levels from early to advanced phase in SSc subsets, reaching its lowest level in advanced dSSc. In conclusion, immunohistochemical and biomolecular results indicate that t-kallikrein is decreased in the skin of SSc patients and decreases progressively from the early to advanced phase of lSSc and dSSc. The decreased expression of t-kallikrein may be involved in the impairment of the sweating process, vessel functionality and angiogenesis.

The diffusion of water into hardened cement samples containing different kinds of additives has been studied for the first time using nuclear magnetic resonance imaging (NMRI). The results indicate that NMRI can be used as a research and industrial method to evaluate the properties (permeability, durability, etc.) of the final cement product.

The X-band electron paramagnetic resonance (EPR) spectra of MoS2/C60 have been studied. A strong T-dependent g-shift and photoconductivity have been observed. The electronic state of molybdenum was found to be Mo3+.

The water proton spin-lattice relaxation time and recovery function of exchangeable water was measured in tricalcium silicate (C3S) gels. The measurements were carried out as a function of the hydration time and grain size. Results show that the hydration of (C3S) is a two stage process. A model is developped

Mise en evidence dans [Rb 1-x (NH 4 ) x ] 2 ZnCl 4 de l'existence d'une region de temperature ou l'elargissement inhomogene incommensurable des spectres de resonnance quadripolaire nucleaire est moyennee. On prouve que des impuretes peuvent empecher le debut de l'ordre incommensurable a grande distance dans des isolants incommensurables

Nuclear magnetic resonance (NMR) was used to determine the pore size distribution of hardened Portland cement pastes. The method is based on the well-known freezing point depression of water when confined inside the pore matrix of a material. It is demonstrated how this technique can be applied in cementitious materials to probe the microstructure of the main hydration product: the cement gel.

This paper is concerned with the relation between the microscopic morphological properties of the cement paste and the cement hydration dynamics. For this purpose, the results obtained by two different methods, i.e. nuclear magnetic resonance (NMR) which monitors cement hydration, and atomic force microscopy (AFM) which acquires precise micrographs of the cement gel surface, have been correlated. It is found that gel-surface roughness is the dominating factor which determines the hydration properties of the system, at least during the late hydration stage.

The Manganese ion cluster compounds allow for a study of the transition from molecular paramagnetism to bulk ferromagnetism. They also show bistability on a molecular level and are thus potentially useful for information storage. In view of a large energy gap the system is ESR silent in the X and Q band but not in high field ESR. Here we report on the first proton NMR study of the Mn 12 acetate compound.

NQR and NMR are -as far as structurally incommensurate (I) systems are concernedamong the methods that were extensively used in the investigation of these systems. Their usefulness is based on the fact that the resonance frequencies vary in space in such a way that reflects the variation of the (I) modulation and give unique information about the static and dynamic states of these systems. The phase solitons are studied from the line-shape calculations and the elementary excitations were clarified from extensive studies of the spin-lattice and spin-s\`pin relaxation times T1 and T2. In addition the investigation of the influence of defects and impurities to the relaxation mechanism, allowes us to clarify some questions on the pinning of the modulation wave.