Advanced electron microscopy and spectrum-imaging techniques were used to investigate the Co/Al2O3/graphene/SiO2 interfaces. Direct observation of pinhole contacts was achieved using FIB cross-sectional lamellas. Spatially resolved EDX spectrum profiles confirmed the presence of direct point contacts between the Co layer and the graphene. The high surface diffusion properties of graphene led to cluster-like Al2O3 film growth, limiting the minimal possible thickness for complete barrier coverage onto graphene surfaces using standard Al evaporation methods. The results indicate a minimum thickness of nominally 3 nm Al2O3, resulting in a 0.6 nm rms rough film with a maximum thickness reaching 5 nm.We report a detailed investigation of the structural and chemical characteristics of thin evaporated Al Concomitantly, the spin relaxation time was also enhanced by more than ninefold, reaching 771 ps at room temperatureet al.141314151617ca. microsecond)13413Graphene is a potential material for spintronic applications because of the combination of its expected long spin lifetime and high electron mobility. The spin diffusion distances observed in graphene are very long; i.e., few micrometers at room temperature1234513489et al.1et al. also evaluated the influence of barrier roughness on the spin relaxation mechanisms by using molecular beam epitaxy MgO and TiO2 seed layers as an alternative for the fabrication of smoother barrier layers on grapheneet al. demonstrated the use of sputtering to deposit continuous 1-nm-thick Al2O3 onto graphene, but this technique damaged the graphene structure and hence reduces the applicability of such an approach1522Tombros 2O3 barriers with variable thickness grown onto single-layer graphene sheets. Advanced electron microscopy and spectrum-imaging techniques were used to investigate the Co/Al2O3/graphene/SiO2 and Co/graphene/SiO2 interfaces. A direct cross-sectional observation of barrier pinholes is reported as well as results concerning the minimal barrier thickness necessary for complete graphene coverage using standard Al evaporation. The results are compared with standard thin Al2O3 deposition onto SiO2/Si substrates.In this work, we report a detailed investigation of the structural and chemical characteristics of traditional thin evaporated Al2O3 barrier samples were analyzed systematically by advanced (S)-TEM techniques. 2O3 barrier thicknesses. The analyses included two substrate regions: with and without graphene. It is important to notice that each Al2O3 barrier sample presents regions with and without graphene at the same substrate, leading to the same nominal barrier deposition for both graphene/SiO2 and SiO2 regions. Parts (a) and (c) of both 2 surface in a region without graphene. For both barrier thicknesses, it is possible to observe a homogenous layer covering the whole substrate surface. The Co layer is also observed as well as the top granular platinum-capping region, purposely deposited during the FIB lamella preparation to protect the integrity of the sample interface layers. It is important to note that both TEM and STEM images present similar features but in reverse contrast. The HAADF STEM images  growth2O3 layer having a minimum thickness of nominally 3 nm, which means thickness reaching a maximum thickness of ca. 5 nm. Although the nominal (3 nm) thickness may lead to complete barrier coverage, AFM measurements indicated a relative high rms roughness of ~0.6 nm  barrier samples, confirming that this thickness is the approximate limit for complete coverage of the graphene by the Al2O3. The Raman analyses are in concordance with the electron microscopy results, indicating that Raman spectroscopy in such experiment is a useful technique for probing the existence of pinholes in tunnel barriers on graphene over large areas.The use of Co sputtering deposition during the fabrication of ferromagnetic contacts may lead to moderate graphene damage. The Raman spectrum of graphene after direct (without barrier) Co deposition contained a prominent defects-related D bandoles see  online. 2O3 barriers. Only the 3-nm-thick  barrier provided complete coverage of the graphene surface, thereby preserving the graphene integrity during the Co deposition. No pinholes were directly or indirectly observed. However, this thicker barrier had a relative high rms roughness of ca. 0.6 nm. The high surface diffusion properties of graphene led to cluster-like Al2O3 film growth. This phenomenon limits the minimal possible thickness for complete barrier coverage on graphene surfaces using standard Al evaporation methods. The minimum required Al2O3 layer thickness for complete coverage of nominally 3 nm becomes ca. 5 nm in practice because of this clustering.In conclusion, direct observation of pinhole contacts was achieved using FIB cross-sectional and advanced high-resolution TEM and STEM analyses. Spatially resolved EDX spectrum profiling showed the nature of direct point-contacts between the Co ferromagnetic layer and the graphene. Raman spectroscopy indicated that moderate damage occurred over large areas of the graphene during the Co sputtering deposition. The presence of pinholes in the barrier structure provided a direct path for Co-carbon collisions. Such pinholes were widely distributed on the samples having 1- and 2-nm-thick  Al2 films that had been thermally grown on silicon substrates. Monolayer graphenes were initially localized using optical microscopy. The crystalline quality and the number of layers of each flake were probed using Raman spectroscopy . Al2O3 barriers were then deposited by thermal evaporation of aluminum in vacuo (base pressure of 10−7 Torr) with posterior ambient oxidation. Different nominal Al2O3 barrier thicknesses (expansion factor of 1.28 from Al thickness) were evaluated; i.e., 1, 2 and 3 nm. The samples were then coated with a Co layer, which represented the ferromagnetic electrodes of a spintronic device. A 4-nm-thick Co layer was deposited by DC-magnetron sputtering at 3 mTorr of Ar, 130 mA (ca. 160 V) and a base pressure of 10−7 Torr. The samples were monitored by Raman spectroscopy between each fabrication step. A Cs-corrected FEI Titan 80/300 S/TEM microscope was used to obtain scanning and conventional transmission electron micrographs of the Co/Al2O3/graphene/SiO2 interfaces. High-angle annular dark field (HAADF) images were acquired using the STEM mode. Space-resolved elemental analyses were performed via energy dispersive X-ray (EDX) spectroscopy to map the layer interfaces. The chemical nature of the Al2O3 barriers was also analyzed using electron energy loss spectroscopy (EELS). The cross-sectional (S)-TEM samples were previously prepared using focused ion beam (FIB) protocols for lamella preparation . Topographical aspects of the Al2O3 barriers were also acquired through atomic force microscopy measurements using a Bruker Multimode 8 AFM operated in the intermittent mode at a drive amplitude of 120 mV with a Si tip having k = 5 N/m.Graphene flakes were obtained by micromechanical cleavage of single-crystal graphite30How to cite this article: Canto, B. et al. On the Structural and Chemical Characteristics of Co/Al2O3/graphene Interfaces for Graphene Spintronic Devices. Sci. Rep.5, 14332; doi: 10.1038/srep14332 (2015).


Idiopathic pulmonary fibrosis acute exacerbation (IPF-AE) constitutes IPF’s most devastating event, representing the unexpected superimposition of diffuse alveolar damage of unknown etiology. Guidelines recommend high-dose steroids treatment despite unproven benefit. We hypothesized that previous immunosuppression and the administration of high-dose steroids adversely affect IPF-AE outcome.We studied all consecutive patients hospitalized in our department for IPF deterioration from 2007 to June 2013. Our protocol consisted of immediate cessation of immunosuppression (if any), best supportive care, broad-spectrum antimicrobials and thorough evaluation to detect reversible causes of deterioration. Patients were followed-up for survival; post-discharge none received immunosuppression.p = 0.041). As unique patients 35.3 % survived; 3 out of 6 (50 %) in the never treated group whereas three out of 11 (27.3 %) in the group receiving immunosuppression (p = 0.685). The history of immunosuppression significantly and adversely influenced survival (p = 0.035). Survival was greater in the never treated group compared to the immunosuppressed patients (p = 0.022). Post-discharge, our IPF-AE survivors had an 83 % 1-year survival.Twenty-four out of 85 admissions (28 %) fulfilled IPF-AE criteria. IPF-AE were analyzed both as unique events and as unique patients. As unique events 50 % survived; 3 out of 12 (25 %) in the group previously treated with immunosuppression whereas nine out of 12 (75 %) in the group not receiving immunosuppression (By applying the above mentioned protocol half of our patients survived. The history of immunosuppression before IPF-AE adversely influences survival. Avoiding steroids in IPF patients may favor the natural history of the disease even at the moment of its most devastating event. Idiopathic pulmonary fibrosis (IPF) is a dreadful, chronic and irreversibly progressive disease leading to death in all patients affected and IPF acute exacerbations (IPF-AE) constitute the most devastating event during its clinical course , 2. IPF-IPF-AE histological picture corresponds to the development of diffuse alveolar damage (DAD) upon usual interstitial pneumonia (UIP) . This coConvinced of its harmfulness, years before the PANTHER trial , the triFirstly, we reviewed the files of all consecutive patients admitted to the pulmonary department of a tertiary teaching hospital, “Attikon” University Hospital, from January 2007 to May 2011 with the diagnosis of pulmonary fibrosis. Secondly, we isolated the cases that represented IPF according to the 2011 IPF criteria . Among tChlamydophila Pneumoniae, Mycoplasma Pneumoniae), chest roentgenography, bronchoscopy, urinary antigen tests for Streptococcus pneumoniae and Legionella pneumophila, bronchoalveolar lavage (BAL), sputum sampling, nasopharyngeal aspirates, endotracheal aspiration, blood/sputum/BAL fluid cultures for microbes, mycobacteria, atypical pathogens, opportunistic infections, fungi, viruses, PFTs and cardiac echocardiography, whenever feasible taking into consideration the clinical condition of each patient. We separated admissions diagnosed as IPF-AE in 2 groups. The first group consisted of patients not receiving steroids or any other form of immunosuppressants prior to admission (treatment naïve or never treated) and the second group consisted of patients receiving prior to admission steroids or any other form of immunosuppressants (ever treated). Our treatment consisted of extended spectrum antimicrobials empirically initiated based mostly on the immunosuppression history of our patients. More precisely, patients never treated with steroids or/and immunosuppressants before the acute exacerbation event were set on antimicrobials for common gram positive, gram negative and atypical pathogens plus therapy against influenza virus pneumonia during the influenza season; patients previously treated with steroids or/and immunosuppressants received in addition to the above mentioned therapy, treatment for Pneumocystis jirovecii and occasionally for cytomegalovirus pneumonia in a documented case. All patients were followed-up after discharge for survival. None of them was treated with steroids or immunosuppression post discharge.The protocol that we applied in every patient admitted with the diagnosis of IPF deterioration has been described in previous publications , 6 and cThis work has been approved by “Attikon” hospital’s bioethics committee decision No 575/11-4-11. No patients’ consent was needed. Some of the data have been published in the form of an abstract [p values < 0.05 were considered statistically significant. Data were analyzed and graphs were created with StatsDirect 2.8.0, StatsDirect Ltd, Altrincham, Chesire, UK.Categorical variables are presented as n (%). Numerical variables are presented as median (range). Comparisons between groups were performed using Cox regression analysis in order to evaluate the influence of the previous use of immunosuppressive therapy on survival. Results are presented as hazard ratios (HR) with 95 % confidence intervals (CI) in parentheses. Time to death according to previous history of immunosuppressive therapy were evaluated with Kaplan-Meier survival curves and log-rank tests. Out of 164 admissions with the diagnosis of pulmonary fibrosis from January 2007 to May 2011, 53 were attributed to IPF representing 37 unique IPF patients. From June 2011 to June 2013 another 32 cases with IPF were admitted to our department (21 unique IPF patients). In total from 2007 to 2013 we recorded 85 IPF admissions that represent 58 unique IPF patients. Diagnosis was obtained by multidisciplinary approach according to 2011 IPF guidelines [Among the 85 IPF admissions an identifiable cause of the patient’s deterioration was found in 49 (58 %), that is 28 (33 %) cases of purulent tracheobronchitis, 7 (8 %) cases of pneumonia, 6 (7 %) cases of heart failure, 4 (5 %) cases of sepsis, 2 (2 %) cases of pulmonary embolism, 1 (1 %) case of pericarditis and 1 (1 %) case of pneumothorax (Table p = 0.007) whilst the need for mechanical ventilation was significantly increased in the ever treated group (p = 0.014). Regarding other parameters  no significant difference was found (Table The descriptives of never and ever treated with steroid groups are presented in Table nd Table . The majp = 0.041). When examining the IPF-AE not as unique events but as unique patients , then out of 17 IPF-AE patients, 6 (35.3 %) survived the exacerbation event. In the never treated group which comprised 6 patients, 3 (50 %) survived whereas in the ever treated group which comprised 11 patients only 3 (27.3 %) patients did (p = 0.685). A univariate Cox regression analysis identified the previous use of steroids as significantly and adversely influencing survival after AE in the ever and never treated groups, with a HR of 3.544 (95 % CI 1.090–11.514), p = 0.035  survived the exacerbation event. In the never treated group 9 (75 %) patients survived whereas in the ever treated group only 3 (25 %) patients did (p = 0.022)  with a 52 % 1-month, 45 % 3-month, 40 % 6-month and 40 % 1-year survival respectively. In the never treated group there was a 70 % 1-month, 65 % 3-month, 65 % 6-month and 65 % 1-year survival respectively , whereas in the ever treated group the median survival was 0.43 months (range 0.2–89) with a 30 % 1-month, 22 % 3-month, 17 % 6-month and 17 % 1-year survival respectively. These differences in survival following a log-rank test were found to be statistically significant  further validate our hypothesis that on the one hand provided a survival benefit in patients with lower lung capacity and on the other hand patients with higher lung capacity and comparable parameters of the exacerbation severity could not be helped by the applied protocol, thus were intubated and subsequently expired. In addition, median overall survival of those ever treated was just 0.43 months with a 17 % 1-year survival while never treated patients showed a 1-year survival of 65 %. Finally, withholding steroids in all survivors of our protocol 83 % of them were still alive 1 year after the exacerbation event.N-acetylcysteine not only had no evidence of physiological or clinical benefit but presented significantly increased rate of hospitalizations, exacerbations and deaths compared to the placebo arm [In 2012 a randomized, double-blind, placebo-controlled trial based on an independent protocol reviewed by a committee appointed by the National Heart, Lung, and Blood Institute, and conducted in 25 clinical centers under the auspices of the Idiopathic Pulmonary Fibrosis Clinical Research Network (IPFnet) was terminated prematurely when the interim analysis demonstrated that IPF patients treated with combination therapy with prednisone, azathioprine and Based on the above evidence it appears to us inconceivable to continue managing IPF patients who precipitate in acute exacerbation being under immunosuppressive treatment with a thirty to hundred fold higher doses of steroids (from 10–35 mg prednisone for the stable IPF patient to 1000 mg methylprednisolone iv pulses for one or more days) and await improvement. The results of our study present our management approach of the rapid deteriorating patient with IPF entering exacerbation by withdrawing corticosteroids and immunosuppressants.Our treatment, as already described, consisted of extended spectrum antimicrobials empirically initiated based mostly on the immunosuppression history of our patients. The protocol adopted by us reflects the common practice in every critical care unit where the critically ill patient developing an ARDS of unknown etiology, or during the evaluation for the detection of the etiologic factor, is managed not by high doses of pulse steroids but by extended spectrum antimicrobials since in this setting it is known that undetectable infection is the most common and the most treatable etiologic condition. Certainly by adopting the above protocol we are conscious that the results of our study are not easily comparable with previous retrospective studies describing the efficacy of specific pharmacological treatment with steroids and immunosuppressants in IPF-AE because such an alternative approach has not been examined before.Current practice for steroids use in IPF acute exacerbations originates from the first description of IPF-AE by Kondoh and coworkers in 1993  who alsop = 0.022). In contrast, the reported mortality of IPF-AE in most studies is very high, usually exceeding 50–60 % and the 3-month mortality rate following an exacerbation event reaches 60–90 % [In our study the never treated IPF-AE population presented a 65 % 1-year survival compared to a 1-year survival of 17 % and a median survival of only 0.43 months in the ever treated group. The overall differences in survival as discussed in the results are significant p = 0.02. In con 60–90 % . Song an 60–90 % . In 2003 60–90 % . The sam 60–90 % . Because 60–90 % . Kondoh  60–90 % . Yokoyam 60–90 % . Finally 60–90 % . In many 60–90 % .Pneumocystis jirovecii than patients not receiving steroids and 36 % of IPF patients grow bacteria in BAL fluid in the absence of clear signs of infection, even before immunosuppression [The survival benefit in IPF-AE patients treated with broad spectrum antimicrobials instead of high dose steroids shown in the present study could be attributed to the fact that they militate the role that microbial populations play in the pathogenesis of such a condition. It is common knowledge that IPF is a disease that severely damages the lung and that IPF lung is vulnerable to any hit, even minor, that could cause DAD in the same manner that direct and indirect lung injuries cause ARDS . Combinipression , 27. Morpression . Moreovepression . Woottonpression . All theIt is to be noted that a limitation of the present study is the small number of patients. Furthermore, it does not include a control arm of IPF-AE patients treated with high dose steroids. The main reason for such a “limitation” was firstly our long standing clinical experience according to which IPF-AE patients treated with high dose steroids didn’t survive and secondarily to it our firm position that such a therapeutic approach would not be appropriate to treat our IPF-AE patients. Of course we are very conscious of the fact that the responsibility of such a scientific opinion that contradicts the official guidelines, although the latter are based on poor evidence, cannot be easily shouldered and that it should be incontestably proved by a prospective properly designed trial examining the role of steroids in the AE-IPF. It is common sense that a single academic center like ours could never support by itself such a trial but needs the scientific, technical and financial support of the international scientific community and of official medical institutions that could conduct a multi-center trial designed and empowered to provide definitive answers to this already long lasting and crucial for IPF patients debate. We are convinced that our proposal reflects not only our view but also the evolving view of other experts that treat IPF-AE patients worldwide , 31, 32.In conclusion by applying the critically ill patient protocol on the management of IPF patients developing acute exacerbation we have shown that half of our patients survived. Furthermore, we found that the history of immunosuppression before IPF-AE adversely influences survival. Avoiding steroids in IPF patients may favor the natural history of the disease even at the moment of its most devastating event.


As of today the dominant technology is based on Si and obtaining graphene with Si is treated as the most advantageous solution. However, the formation of carbide during the growth process makes manufacturing graphene on Si wafers extremely challenging. To overcome these difficulties and reach the set goals, we proposed growth of high quality graphene layers by the CVD method on Ge(100)/Si(100) wafers. In addition, a stochastic model was applied in order to describe the graphene growth process on the Ge(100)/Si(100) substrate and to determine the direction of further processes. As a result, high quality graphene was grown, which was proved by Raman spectroscopy results, showing uniform monolayer films with FWHM of the 2D band of 32 cm It is an irrefutable fact that the best quality graphene in terms of structural integrity and electrical properties is obtained by mechanical cleavage of highly oriented pyrolytic graphite2Recently, single crystal hexagonal boron nitride (h-BN) has been proposed as an ideal substrate for epitaxial growth of grapheneLately, among many interesting methods developed worldwide781011141718Since graphene and its extraordinary properties were described and analyzed in depth, it has been considered as a material to be implemented in various fields. One of the leading ideas which appears to be a progressive concept is to apply graphene to complementary metal oxide semiconductor technology (CMOS). In order to widen the range of possible graphene applications, for example in high frequency electronics, it is desirable to grow graphene films directly on arbitrary insulators or semiconductor surfaces instead of on a most commonly used copper substrate. Ideally such insulating or semiconducting layers are deposited on Si wafers used commonly in integrated circuit (IC) manufacturing. Growing graphene directly on Si wafer surface is extremely challenging due to the tendency to form carbides. This forces researchers into looking for alternatives, for instance offered by germanium substratesex-situ removal of native oxides or preceding graphene growth with the deposition of fresh Ge layers, which, without a doubt adds value to the fabrication process. As an alternative to direct growth, graphene transferring from a copper substrate is considered. Ruoff et al.In this paper, we intend to present, for the first time, CVD growth of graphene on epitaxial Ge(100) layers deposited on Si(100) wafers, which is the preferred wafer orientation in CMOS technology. The cost advantage offered by this approach is linked with the bulk buying of wafers and what is even more important manufacturing compatibility of Si(100). Additionally, when compared with techniques described in other reportsAdditionally, in the literature there are examples of graphene growth modeling; however, the vast majority of these papers are related to graphene synthesis on substrates other than Ge(100)/Si(100), including mostly copper foils2728In order to determine and understand the kinetics of the graphene growth process on the Ge(100)/Si(100) substrate, the nucleation stage was investigated as a function of methane flow. During the processes different methane flow were introduced into the growth chamber. The processes were performed in such a way that the results of the initial steps of graphene growth were observed. In other words, the processes were stopped before graphene formed continuous films and, hence, graphene flakes rather than continuous films were visible on the surface of Ge(100)/Si(100). Next, after having obtained a set of samples partially covered by graphene, a round of longer processes was completed with the aim of observing the formation of a continuous graphene film and the accompanying side effects like discontinuities, grain boundaries or secondary  graphene ad-layers.4 flow varied from 5, through 10, up to 15 sccm (standard cubic centimeters per minute). The collected Raman spectroscopy results confirm the presence of graphene layers in the case each of the examined samples  relative to free-standing graphene indicate that on the surfaces of the samples more than one layer of graphene was obtained31D/IG ratio equal to 0.4, 0.57 and 0.76 for 5, 10 and 15 sccm, respectively can be accounted for by two factors, namely the distance between isolated defects or the existence of very small graphene monocrystalline domains of the order of 40 nm33At the first attempt the Raman quality was investigated as a function of methane partial pressure. As for the preset growth parameters, CH samples . WidenedThere is a direct correlation between carbon transport (as methane) and the growth rate of graphene flakes. The methane flow can also imply the nucleation rate (i.e. the number of new flake nucleations per time unit). In the simplest view, if growth is mass transport-limited, both values (growth rate and nucleation rate) should be close to proportional to the precursor partial pressure. In such a case, the precursor flow value does not affect the overall growth pattern of flakes, except the timescale. Several factors can disrupt this image. Nucleation can be quickly saturated by a finite number of nucleation defects on the substrate surface, as a result of which the growth rate increases faster than the nucleation rate. On the other hand, nucleation can get more efficient when the precursor flow is increased because of the limited migration of surface ad-atoms. The higher the precursor partial pressure, the shorter the time for single ad-atom to migrate and attach to a flake edge before getting companions and nucleating a new flake (even without any nucleation defects).4 flow equal to 5, 10 and 15 sccm are different and the relationship between the growth rate and the nucleation rate was not the same for various CH4 flows. In each pair of images (SEM and simulation) different areas are marked with arrows. The varied areas in bluescale in simulation pictures correspond to the number of graphene layers  seen in SEM images and the lighter blue areas in simulation images represent uncovered Ge surface, without graphene on top. Pictures suggest that the nucleation rate increases faster than the growth rate with raising the CH4 flow. Besides, the images show some secondary (2ML) or even 3ML or 4ML nucleations overgrowing the first layer (1ML). These ad-layers seem to nucleate and to increase their size with a highly varying rates, when comparing all three pictures.SEM images  show thaPN and PC, as follows:PN is the probability of growing the graphene unit cell in coordinates of a single unit cell  per time unit, if it does not have any already grown closest neighbours – the “nucleation” case.PC is the probability of growing the graphene unit cell in coordinates of a single unit cell per unit time, if its closest neighbour has been already grown – the “continuation” case.In order to provide a more precise quantitative interpretation of both the growth statistics and the observed growth patterns of graphene on Ge(100)/Si(100) substrates we have developed a Monte-Carlo type model of the layered growth. The model employs two primary parameters, PC /PN). The employed term “unit cell” assigns an arbitrary unit lattice area, which in the limiting case can be the crystal lattice unit cell. When more than one nearest neighbour is already grown, the growth probability can be simply set as the additive function of these neighbours.The later used convenient parameter is a ratio of these two probabilities , 2) the probability ratio of continuation on the graphene layer to continuation on the substrate - . These factors describe the formation of the ad-layers. If analogous parameters were required for the description of higher order (ad-) ad-layers, they would be denoted as , ,  or similar.The model applies a pair of secondary parameters: 1) the probability ratio of secondary nucleation on the already grown graphene layer to nucleation on the substrate - (The simulation process consisted of repeating the following sequence: 1) Randomly selecting coordinates of a unit cell, 2) Checking the growth state of the nearest neighbour unit cells and assigning the growth probability value, 3) Drawing the occurrence of a given growth step event. The calculations were usually completed for the square lattice frame of 1000 × 1000 or 500 × 500 unit cells. The computed image of the primary (1ML) pattern  does not depend on the calculation frame dimension, when scaling the parameters as below.D is the calculation image frame dimension (in unit cells), whereas A and B assign two calculation setups. If the PC /PN ratio and image dimension are fixed, the image primary pattern does not depend on the PN absolute value, when scaling the time as below:where PC /PN ratio and the image dimension D describing growth. It is easy to show that this function is a quotient: In conclusion, the primary (1ML) image is defined by only two values. The first is the function of time describing progress in the growth process: PN,.. and PC,.. values correspond to the probabilities of the occurrence of growth of a graphene unit cell after single drawing of the coordinates of this unit cell (in a single sampling of this cell). The “time” value corresponds to the average number of samplings of a single unit cell .Several attempts to fit the microscope images of graphene on Ge(100)/Si(100) substrates with simulation have quickly given quite satisfactory patterns. Below  there arPC /PN) ratio decreases significantly with increasing the CH4 partial pressure – the continuation of the existing flakes becomes less preferred to nucleation of the new ones. Faster raising of the nucleation rate than the lateral growth rate with CH4 flow suggests that the nucleation is suppressed by some process, especially at a low precursor partial pressure. The most obvious explanation is as has been mentioned earlier: nucleation can be prevented by the migration of ad-atoms to the nearby flakes; when increasing the precursor flow, the time, in which ad-atom is lone, shortens. Before reaching a flake, the ad-atom transits into the ad-atom cluster. The clustering slows or stops migration and results in the nucleation.The fitting results show that the , which is related to the secondary (2ML) layers, does not exhibit a monotonic behaviour. The 2ML nucleation ratio  and even directly the nucleation rate alone  shows a strong minimum around the medium CH4 flow, while outside this minimum they depend on the CH4 flow in the same manner as in the case of the primary nucleation – the PN,2ML/PN ratio is almost constant there. We cannot offer a clear explanation for this effect yet. Such explanation would have to distinguish between the Ge(100)/Si(100) surface area and the 1ML graphene layer area as a substrate. It can, however, be supposed that the clustering process of ad-atoms includes an intermediate step during which they become exceptionally mobile on the graphene 1ML surface (while this does not take place on other surfaces) and this intermediate step is preferred by the medium precursor flow through a surface or by a gas phase reaction. Despite these differences in nucleation, the growth continuation parameter PC,2ML/PC regarding the secondary (2ML) graphene layer does not significantly depend on the CH4 partial pressure and is close to PC,2ML/PC = 1. It means that the continuation of flakes has a similar growth rate for both 1ML and 2ML flakes.The next parameter  flakes are very often overgrown by next-order layers, more often if the CH4 flow is higher. While the nucleation rate of higher-order (>2ML) ad-layers grow faster than the 1ML nucleation rate, the continuation rate seems to be more similar to the 1ML continuation rate.The nucleation rate of the higher secondary layers  seems to grow monotonically with the CHgr) and simulation time parameter within growth pairs is not directly proportional. This affected correlation and confirms the existence of a time offset before the nucleation becomes visible. The delay was clearly observed in other growth experiments, not shown in this paper. This offset partially results from the specific operation of the hardware; however, in its larger part it has to be induced by another factor. Most probably, it is related to the nucleation stage of 1ML graphene on Ge(100)/Si(100). The nucleation cluster with just a few atoms collects subsequent atoms much slower than a flake, until getting a regular lattice and becoming visible in SEM images.The relation between the experimental growth time /Si(100) is affected by the migration of ad-atoms on the surface and this nucleation can be increased by accelerated clustering of ad-atoms in a high precursor partial pressure. Secondly, there is a striking difference between the first ad-layer nucleation on graphene (2ML) and primary nucleation on germanium since the ad-layer (2ML) nucleation rate has a strong minimum for a particular precursor flow. Thirdly, the nucleation, as such is a relatively slowly progressing step, introducing a time delay before substantial covering by graphene begins.−1) and the 2D/G intensity ratio higher than 2 are observable, which confirms the presence of a high quality and homogeneous monolayer graphene film.On the basis of the above mentioned results further optimization steps in the growth process of graphene on Ge(100)/Si(100) substrates were made. The methane flow was reduced and the time of growth was extended. As a result, a uniform graphene film was achieved. Additionally, in order to confirm the presence of the high quality monolayer of graphene on Ge(100)/Si(100) substrates STM measurements were performed. In summary, the influence of the methane flow on the graphene nucleation mechanism, growth rate, uniformity and structural quality has been investigated. High quality graphene has been grown on Ge(100)/Si(100) substrates, which has been mainly confirmed by the results of Raman spectroscopy measurements. Also, the presented simulation and quantity analysis show that graphene growth on Ge(100)/Si(100) substrate can be described by a simple stochastic model with a very low number of parameters. The influence of the substrate lattice structure, extended defects and growth anisotropy are restrained enough to make such a description possible. The excellent alignment between the experiment and the simulation means that in the course of further investigation a convincing physical model can be proposed to describe the whole process of graphene growth. The presented attempt, including particularly direct growth on the Ge(100)/Si(100) substrate combined with modelling of the growth process, was shown here as a viable alternative enabling the introduction of graphene with its unique features to CMOS technology.2 in the ratio of 20:1. It was found that the optimal roughness of the substrate is achieved when the step growth is preceded by the substrate’s annealing at pure hydrogen atmosphere in order to in-situ reduce native oxidesIn the present work graphene films were synthesized in a 6-inch Aixtron Black Magic system by the CVD method. As a substrate we used (100)-oriented Ge layers deposited by the CVD method on Si (100) wafers. To ensure optimal temperature conditions, thus preventing Si diffusion through a Ge layer and Ge melting, the temperature was monitored and set separately and simultaneously in bottom and top heaters. The temperature was chosen in the range between 900 °C and 930 °C with a temperature ramp up rate of 20 °C/min. During the process of graphene deposition the pressure range of 700 to 780 mbar was sustained. Methane gas was used as a carbon precursor in the mixture of Ar and H−10 mbar with a Multiprobe P system made by Omicron GmbH.The characterization of the properties of graphene grown directly on Ge(100)/Si(100) substrates was performed by Raman spectroscopy using a Renishaw system with a 532 nm Nd:YAG laser as an excitation source with the laser spot diameter on the sample surface of approximately 0.3 μm. The surface of graphene was investigated using the In-Lens secondary electrons detector (true SE1) and the Energy selective Backscattered electron  detector, both positioned on the optical axis of the Gemini™ column of the Auriga CrossBeam Workstation (Carl Zeiss). The energy of primary electrons in the scanning beam was set at 500 eV so as to reveal the morphology of the ultra-thin layer of graphene (single layer) and simultaneously distinguish different phases present on the substrate based on the compositional contrast (low-loss BSE). STM measurements were conducted under base pressure of 2 × 10How to cite this article: Pasternak, I. et al. Graphene growth on Ge(100)/Si(100) substrates by CVD method. Sci. Rep.6, 21773; doi: 10.1038/srep21773 (2016).


This data article shows the expression levels of specific podocyte injury markers and podocyte slit diaphragm protein nephrin in obese and lean Zucker rat glomeruli. It also contains information on the effect of the overexpression of transcription factor FOXC2 on the ratio of F- and G-actin and the expression level of ZO-1 in differentiated human podocytes. The article also shows data on the effect of treatments of differentiated podocytes with various factors associated with obesity and diabetes on the expression level of FOXC2. The detailed interpretation of these data and other aspects of podocyte injury mediated by upregulation of FOXC2 can be found in “Overexpression of transcription factor FOXC2 in cultured human podocytes upregulates injury markers and increases motility  Specifications table•The obese Zucker rats show a trend towards upregulation of podocyte injury markers in glomeruli.•The obese Zucker rats with the highest level of proteinuria express least nephrin in glomeruli.•in vitro does not change the F-actin/G-actin ratio, or the expression level of the tight junction protein ZO-1.Overexpression of FOXC2 in differentiated human podocytes •Several obesity and diabetes-associated factors were found not to upregulate FOXC2 in differentiated human podocytes.1Quantitative Western blotting reveals that podocyte injury markers active beta-catenin, desmin and fibronectin show a trend of upregulation in the glomeruli of 40 weeks old obese Zucker rats compared to lean controls A and B. 22.13VO4 and 1× Complete Proteinase Inhibitor Cocktail  at 4 °C for 30 min. Detergent-insoluble material was removed by centrifugation .Obese (fa/fa) and lean (fa/+) Zucker rats (Crl:ZUC-Leprfa) were obtained from Charles River Laboratories . Blood glucose values were measured from tail vein samples using OneTouch Ultra glucometer . The urinary albumin to creatinine ratio was determined from spot urine samples. Albumin was measured with rat albumin ELISA kit  and creatinine using CREA plus enzymatic assay  and Roche clinical chemistry analyzer . The exp2.275 μg of glomerular lysates were separated on a 10% SDS-PAGE gel, transferred to PVDF-FL membranes  and blocked with Odyssey blocking buffer  diluted 1:1 with phosphate buffered saline (PBS). The membranes were incubated with mouse anti-active β -catenin , mouse anti-desmin 37EH11 Treatment of cultured human podocytes with obesity- and diabetes-associated factorsConditionally immortalized human podocytes (AB8/13) were cultured as described in Datta et al. 2.3® . The expression levels of FOXC2 mRNA were normalized to GAPDH using the comparative Ct method (DDCt).Total RNA was isolated, treated with DNase I and reverse transcribed into complementary DNA (cDNA). The quantitative PCR was performed using TaqMan gene expression assays  for hFOXC2 (Assay ID: Hs00270951_s1) and hGAPDH  as in 2.4g centrifugation at 37 °C for 1 h that pellets the F-actin and leaves the G-actin in the supernatant. Samples of supernatant and pellet were separated by SDS-PAGE and actin was quantified by Western blotting using the rabbit polyclonal anti-actin antibody provided in the kit.FOXC2 was lentivirally overexpressed in differentiated human podocytes as described in Datta et al. 2.5t test .Results are presented as mean±SD. Statistical analysis was performed using Student׳s


The electrochemical capacitance of the material exhibits a dependence on bias voltage, a phenomenon observed by other groups when studying graphene quantum capacitance. The plasma-assisted graphitization, which dominates the graphitization process, is analyzed and discussed in detail.High surface area electrode materials are of interest for a wide range of potential applications such as super-capacitors and electrochemical cells. This paper describes a fabrication method of three-dimensional (3D) graphene conformally coated on nanoporous insulating substrate with uniform nanopore size. 3D graphene films were formed by controlled graphitization of diamond-like amorphous carbon precursor films, deposited by plasma-enhanced chemical vapour deposition (PECVD). Plasma-assisted graphitization was found to produce better quality graphene than a simple thermal graphitization process. The resulting 3D graphene/amorphous carbon/alumina structure has a very high surface area, good electrical conductivity and exhibits excellent chemically stability, providing a good material platform for electrochemical applications. Consequently very large electrochemical capacitance values, as high as 2.1 mF for a sample of 10 mm Ever since the first experimental proof of graphene’s existence3678910678910812Previous fabrication processes related to producing 3D graphene films on porous substrate have usually involved multiple fabrication steps and required the use of graphene oxide1112131415131413171820212) is achieved. The material properties of 3D graphene are analyzed by Raman spectroscopy, Scanning Electron Microscopy (SEM), Transmission Electron Microscopy (TEM) and Electron Energy Loss Spectroscopy (EELS). The electrical and electrochemical properties are investigated by conductance measurements, Cyclic Voltammetry (CV), and Electrochemical Impedance Spectroscopy (EIS). The chemical stability of the material is studied by chemical etching using hydrofluoric acid (HF). Based on the results of the material characterization and analysis of the plasma-material interaction, it is concluded that the growth mechanism is a combination of deposition and graphitization of an ultrathin amorphous carbon layer on AAO in PECVD.This paper presents a technique for one-step graphene fabrication on nanoporous anodic aluminium oxide (AAO) using plasma-enhanced chemical vapor deposition (PECVD). We demonstrate direct catalyst-free graphene growth on AAO and investigate the formation of graphene in the nanopores. High effective surface area graphene grown over well-defined nanopores with large capacitance (as high as 2.1 mF for a sample of 10 mm9 cm−2 pore density). Unless specified otherwise, the following characterizations are made based on the sample fabricated by method 1.−1), G (1595 cm−1) and 2D (2691 cm−1) peaks. The rise of D and D’ (1629 cm−1) peaks suggest the existence of defects in the sample3 type defects242525−1, which is slightly larger than that of a commercially purchased CVD monolayer graphene on SiO2 (32.3 cm−1) consisting of a single 2D component but lower than of bilayer graphene (50 cm−1), which contains four 2D peak components1627) and 2D 91 cm−1 p) and 2D 91 cm−1 pand D’ 16 cm−1 pea2 carbon hybridization in the a-C-AAO samples−1 and the I(D)/I(G) is 1.8. The Raman spectrum indicates a defected few-layered graphene was obtained, confirming the temperature driven graphitization process16312 content in our study than in previous reports2331212223To analyze the atomic structure and a number of graphene layers in the samples, TEM studies of the G-AAO membranes have been performed. 332 fractions are 77.2% and 50.9% in G-AAO and in a-C-AAO, respectively, where glassy carbon (100% sp2) was used as the reference383 peak in G-AAO supports the presence of a remaining amorphous a-C carbon layer underneath graphene layersTo confirm the full coverage of the graphene layer over AAO, G-AAO was inserted in HF acid  for 22 hours to study the chemical stability of the materialTo test the continuity and electrical conductivity of the formed graphene layers on AAO we performed a two point probe electrical measurements. The sheet resistance measured horizontally along the surface, as schematically seen in s is the solution resistance and R the resistance to charge transfer to Electrochemical capacitance  of a G-A452O3 and α-Al2O3 formed at high temperature502O3 and α-Al2O3 were involved in the plasma-enhanced graphitization process to form graphene due to the ion bombardment on the surface by energetic particles, while in thermal annealing γ-Al2O3 was well separated by the a-C layer from the surface graphene layer. The detailed a-C/γ-Al2O3/AAO structure can be found in ref. The two presented fabrication methods of 3D graphene described in 2122233433It has also been observed in the experiments that the growth of graphene or a-C in PECVD can be effectively controlled by a proper choice of a spacer under the sample, while using the same plasma growth conditions. The use of dielectric spacer allowed direct production of graphene on AAO and reaching 600 °C higher sample temperature of AAO on a dielectric spacer compared to a metal stage. The ability to control the sample temperature by the spacer in the PECVD process was found also extremely important for graphene production reproducibility. In some occasions, it was possible to obtain G-AAO without separating the AAO from the stage but the repeatability was low. Only one experiment out of ten could successfully produce G-AAO without the spacer.Intuitively, the dielectric spacer plays two roles that both lead to an increase of the temperature of the sample in the plasma. Firstly, the spacer introduces thermal isolation between the sample and the stage and therefore reduces the thermal dissipation of the sample. Secondly, the spacer induces perturbation to the plasma near the sample surface, which can lead to complicated plasma-material interactions and a sample temperature change, because plasma is the only source ‘heating up’ the sample (plasma-enhanced graphitization). The increase in sample temperature has also a significant impact on the surface chemistry, which can strongly affect the carbon layer formation.For the quartz spacer of 0.35 mm thick, our calculation using Fourier’s lawEk) on substrate surface is mainly determined by the electric potential in plasma sheath and provides the energy for ions to bombard the substrate surface. Ions move directionally within the plasma sheath driven by the potential drop53Ek can be roughly estimated as Ek  ≈ 5.2Te ≈ 26 eVTe ≈ 5 eV is the electron temperatureEk a value greater than the energy released in chemical processes, for example, the hydrogen binding energy (around 4.5 eV)Analysing all the chemical processes in plasma including plasma-material interaction, and hence simultaneously tracking every charged particles collision event, requires massive Monte-Carlo simulations of plasma53The ion bombardment is believed important in PECVDλD, where λD is Debye length) is placed on the top of the metal stage, the stable ambipolar field is created on the dielectric surface for both low and high bias voltages, as demonstrated by the red and purple solid curves in φ0 is the potential determined by the ambipolar field. Therefore placing the dielectric on top of the metal provides a more stable plasma sheath than on the metal. The stable sheath offers continuous ion bombardment on AAO hence increases the temperature.By solving Poisson-Boltzmann equations53λD ≈ 53 μm if Te = 5 eV and the electron density is 1011 cm−3 in microwave plasma source53Although AAO itself is a dielectric, a rough estimation gives Another possible effect on temperature increase is surface charging, namely the accumulation of charges on the dielectric surface in plasma. Although the potentials on dielectric and on metal at far distance are found to be similar due to the same amount of net charges , the den3 with effective surface area of 883 cm2 was achieved. This implies the potential for using G-AAO as super-capacitors for energy or/and biological applications. The capacitance dependence on the bias voltage of G-AAO was also observed.The possibility of catalyst-free graphene growth on a porous dielectric AAO material was explored. Two different fabrication methods of graphene on AAO were developed based on plasma-enhanced and thermal graphitization of ultrathin a-C precursor layers in PECVD. Microscopic studies confirmed that defected FLG is conformally obtained on the whole internal and external surface of nanoporous AAO. The samples retained the well-defined nanoporous structure of the AAO and become well conductive after the graphene deposition process. Overgrowth of G-AAO and occlusion of pores was an intermittent problem, which can be avoided by using lower plasma power. Due to the large surface area of the porous structure, the electrochemical capacitance as large as 2.1 mF for the sample of 10 mmEELS and Raman strongly suggest that plasma-enhanced graphitization of a-C is the growth mechanism of G-AAO in PECVD. To improve the reliability of the G-AAO film production and achieve higher substrate temperature in PECVD for production of graphene, the sample plasma annealing process was investigated by studying the surface charging effect and the potential distribution on the plasma-material interface. It was found that introducing a dielectric spacer in between the sample and the metal stage leads to 600 °C higher sample temperature and improved repeatability than on the metal stage due to several reasons, such as stabilization of the plasma sheath, surface charge accumulation for direct annealing, and reduction of the power dissipation.2/CH4: 750/10 sccm; microwave power: 1.7 kW; pressure: 85 Torr. The temperature of the samples was monitored by an external pyrometer outside the chamber and a thermocouple in the molybdenum stage. Assistive stage heating prior to the PECVD process was used to prevent the quartz spacer from breaking due to the sudden temperature rise coming from plasma. Raman spectroscopic studies were conducted on a Renishaw inVia Raman Microscope with a laser wavelength of 532 nm and a laser spot size of 10 μm. SEM analyses were performed on FEI Nova Nanolab 200. TEM and EELS characterizations were conducted on a JEOL 2100F. The electron energy applied in EELS studies was 80 keV, and the collection angle was 16 mRad. 5 samples were tested in electrical and electrochemical measurements. Electrochemical impedance spectroscopy (EIS) data was acquired using an eDAQ z100 Electrochemical Impedance Analyzer connected to an eDAQ EA163 potentiostat. The frequency range in the EIS measurement was set from 1 kHz to 100 kHz, and the amplitude of the AC signal was kept as small as possible (30 mV) to minimise quantum capacitance effects. Capacitances values were estimated by fitting EIS data to a model circuit using ZMan v2.2 software .AAO samples with 55 nm pore diameter and 100 μm thickness  were placed within the growth chamber of a microwave PECVD system (iplas GmbH). Graphene (the one-step method) and a-C (the first step in the two-step method) were grown on AAO using the following reactor conditions: HHow to cite this article: Zhan, H. et al. Direct fabrication of 3D graphene on nanoporous anodic alumina by plasma-enhanced chemical vapor deposition. Sci. Rep.6, 19822; doi: 10.1038/srep19822 (2016).


It is shown that the addition of graphene pins the grain growth of the ceramic matrix grains, leading to a change of the microstructure at low filler concentrations. As a consequence, the composites exhibit two percolation thresholds and their dielectric properties are not only determined by the dielectric properties of the constituents and their relative fractions but also the microstructure of the composite must be considered. Additionally, a giant increase of the dielectric constant has been found around the percolation thresholds in barium titanate–graphene composites. In particular, values of the dielectric constant up to 45,000 and 15,000 were found at 1 kHz in composites containing 0.4 and 0.6 wt. % graphene, respectively.Al It is increasingly being recognized that new applications for materials require functions and properties that are not achievable with monolithic materials. In this sense, composites formed by a ceramic matrix and a conductive second phase are very interesting materials since their physical properties, such as optical, electrical, and magnetic properties as well as tribological, corrosion resistance, and wear properties can be tailored, making them attractive for many new applications –4. In pa2O3/graphene composites with graphene concentrations between 0.56 and 1.24 % weight and BaTiO3/graphene composites with graphene concentrations between 0.1 and 0.6 % weight are studied in the frequency range of 10−1–106 Hz.The dielectric properties of insulator–conductor materials, such as conductivity and permittivity, show a critical behavior when the fraction of the conductive phase reaches the percolation threshold , 7, whic3 and KMnO4. Concentrated H2SO4 (360 mL) was added to a mixture of synthetic graphite (7.5 g) and NaNO3 (7.5 g), and the mixture was cooled down to 0 °C using an ice bath. Afterwards, KMnO4 (45 g) was slowly introduced in small doses to keep the reaction temperature below 20 °C. The solution was heated to 35 °C and stirred for 3 h. At that point, a hydrogen peroxide (H2O2) 3 % solution (1.5 L) was slowly poured, giving rise to a pronounced exothermal effect up to 98 °C. The reaction mixture was stirred for 30 min and centrifuged (3700 rpm for 30 min) to discard the supernatant. The remaining solid material was then washed with 600 mL of water and centrifuged again; this process being repeated until the pH was neutral.Graphene oxide was synthesized from synthetic graphite by the modified Hummers method . This me−1) was prepared in 1-L batches and kept under ultrasound for 10 h. Afterwards, the suspension was centrifuged (3700 rpm for 30 min) to discard the filtered supernatant. To prepare the suspensions for organic solvents, water was evaporated in a rotary evaporator and 10 mL of each solvent was dispersed into 1 mg of solid to then sonicate for 30 min. Details on the characteristics of graphene oxide are given elsewhere [A colloidal suspension of individual graphene oxide sheets in purified water  and BaTiO3  powders for ceramic matrices with an average particle size of around 150 and 700 nm, respectively, were dispersed in distilled water then mixed with the graphene oxide dispersion and finally ball milled for 1 h. The homogeneous mixtures were spray dried and uniaxially pressed (30 MPa) prior to spark plasma sintering in an FCT-HP D25/1 apparatus with a heating rate of 50 °C·min−1 under an applied pressure of 80 MPa, a holding time of 1 min and in vacuum (10−1 mbar). The final sintering temperature was 1500 °C in the case of Al2O3/graphene composites and 1100 °C for BaTiO3/graphene. Densities close to 100 % were found in all composites.Al−1. Microstructure was characterized by field emission scanning electron microscopy (FESEM) on a QUANTA FEG 650 and by transmission electron microscopy (TEM) on a JEOL-JEM 2100F. The dielectric properties of the samples were studied by standard low-frequency impedance measurements (PSM1735-NumetriQ).Powder X-ray diffraction analysis  was used to determine possible high-temperature chemical reactions between components in sintered samples. Raman spectroscopy was performed on a Renishaw 2000 Confocal Raman Microprobe  using a 514.5-nm argon ion laser. Spectra were recorded from 1100 to 3500 cm2O3/graphene composites  and G (1583 cm−1) are narrow and present similar intensities (ID/IG = 0.92). A shoulder corresponding to the D’ band (1620 cm−1) is observed next to the G band and a well-defined structure is also present in the range 2500–3500 cm−1. A single and narrow 2D peak is centered around 2700 cm−1; therefore, according to Ferrari et al. [D and G bands together with the shape of the 2D band, indicates that the state of the graphene in these composites is intermediate between those treated at 1000 and 2000 °C in that work, which agrees with the sintering temperature of 1500 °C.X-ray diffraction analysis of Altes Fig. a only shtes Fig. b. Bands i et al. , the prei et al. , consideElectron-dispersive X-ray spectroscopy performed along the yellow line in Fig. 2O3 grain sizes as a function of the graphene concentration in the samples. While monolithic alumina sintered by SPS under the same conditions presents 10-μm grain sizes [2O3 grain growth. This result is analogous to the one reported in ref. [Field emission scanning electron microscopy images Fig. a–d show in sizes , the gra in ref.  for alum2O3/graphene composites at a frequency of 1 kHz. It should be noted that at low frequencies, the conductivity reaches a plateau regime, as it corresponds to a d.c. regime. In the case of monolithic alumina, its relative dielectric constant and conductivity are respectively ε′ = 10 and σ = 10−11 S·cm−1 in agreement with previously reported values in the literature [Figure terature , 26. Forterature . In thisterature . The losThe existence of a double percolation threshold in ceramic matrix–graphene composites can be very interesting from a technological point of view as it can be used to obtain a giant increase of the dielectric constant in a high permittivity matrix by the addition of very small amounts of graphene as will be shown next.3. Again, no reaction phases are noticeable in the diffractogram corresponding to the composite with the largest amount of graphene. In this case, this is a very relevant result because some impurities, such as TiC, or different barium oxides could be expected in dense compacts if they were sintered by conventional methods. The use of SPS has allowed obtaining dense composites  by sintering them at low temperatures and for very short times. In order to study the structure of the graphene after sintering, Raman spectra were taken and are shown in Fig. D (1355 cm−1) and G (1583 cm−1) are narrow and present similar intensities, with band D being even more intense than band G (ID/IG = 1.06). A qualitative comparison with the results by Botas et al. [D, G, and 2D bands, indicates that the state of the graphene in these composites is very similar to graphene treated at 1000 °C in the reference given above, which agrees with the sintering temperature of 1100 °C. The 2D peak is centered around 2690 cm−1 and presents a single component; therefore, according to Ferrari et al. [The X-ray diffraction analysis Fig. a of the s et al. , considei et al. , the pre3/graphene composites  and the dielectric losses of the composites (~4–5 %) are due to a reduction of the Ti4+ to Ti3+ originated during the sintering process in vacuum. With increasing graphene content, the conductivity increases until it reaches a maximum value (~2.5·10−5 S·cm−1) at 0.4 % graphene. Then, conductivity abruptly decreases for the 0.45 % graphene composite, displaying again a conductivity behavior similar to that of BaTiO3. In a similar way as it happens in the Al2O3/graphene composites shown above, the pinning effect on the matrix grains by graphene sheets induces a local decrease (at the grain boundaries) of the effective graphene concentration and, therefore, a decrease in the composite conductivity. Finally, the conductivity of the composites increases again for concentrations over 0.45 %.The dependence of the microstructure versus graphene content is expected to have a deep influence on the dielectric properties of the composites. Fig. 3/graphene composites at a frequency of 1 kHz. In particular, the 0.4 % composite exhibits a permittivity value of ε′ ≈ 45,000 and the 0.6 % composite of ε′ ≈ 15,000 compared to the value of 2900 for the monolithic BaTiO3 ceramic. However, these large values of the dielectric constant are accompanied by large increases of the loss tangent  of the dielectric constant has been found in BaTiO3/graphene composites by introducing very small amounts of graphene. In particular, a permittivity value around 45,000 was obtained for the composite of 0.4 wt. % of graphene and around 15,000 for the 0.6 % graphene composite. This opens a route to develop giant dielectric constant composites with very low concentrations of conductive phases.In summary, it has been shown that low concentrations of the filler produce a strong change in the microstructure of the ceramic matrix composites, particularly on the average grain size of the ceramic matrix. When the aspect ratio of the conductive filler is large enough, the pinning effect of graphene on ceramic matrix modifies the spatial distribution of the conductive phase in such a manner that the percolation threshold is reached twice as the result of the change of local graphene concentration. The dielectric properties of Al


The proliferation and expansion of the malignant PC producing a monoclonal immunoglobulin eventually results in BM failure with anemia, skeletal involvement with osteolytic lesions and hypercalcemia, and renal failure due to the excessive production of paraprotein.2 However, most patients will still eventually suffer a fatal relapse after an initial effective therapy. This is due to the persistence of chemotherapy-resistant precursor cells3 in the BM even after destruction of the bulk of tumor cells4 and, accordingly, the disease will become more and more refractory to chemotherapy after each additional line of treatment.There have been significant therapeutic advances over the past decade and the median survival of myeloma patients has increased to ~6 years.5 have shown significant clinical efficacy in different solid tumors7 and also hematological malignancies.8 PD-L1 is expressed on different antigen-presenting cells and it has been suggested that PD-L1 is absent from normal PCs10 while it is expressed on myeloma cell lines9 and primary myeloma tumor cells from patients with MM.10 However, so far it has remained controversial whether normal PCs from myeloma patients or healthy donors are also PD-L1 positive and it is unclear whether quiescent myeloma-propagating cells express PD-L1 as a therapeutic target.Immunotherapy could play an important role in eradicating chemotherapy-resistant myeloma cells from the BM of the patients and one approach in particular has been shown to be very promising. Monoclonal antibodies targeting PD-L1 or its receptor PD-1, which is expressed on the surface of exhausted T and B cells and is involved in the maintenance of peripheral self-tolerance,We recently performed a flow cytometry-based analysis of BM samples from 11 healthy donors, 15 patients with monoclonal gammopathy of undetermined significance, 6 patients with smoldering MM and 51 patients with MM. All the patients and healthy subjects had identifiable CD38+/CD138+ PCs in their BM but, as expected, the number of PCs was the highest in our patients with active MM . When wen=22) as defined by the absence or presence of CD19/CD56 and CD45/CD28, respectively. We did not detect any difference in the expression of PD-L1 among the patients' PC subtype as defined by positivity for CD19 and CD56, in particular we did not observe an abnormal expression on those PCs showing the typical CD19−/CD56+ aberrant phenotype  in a contact-dependent manner. These Tregs demonstrated a suppressive phenotype and an increased PD1 expression compared with naturally occurring Tregs.12 Furthermore, It has recently been shown that the PD-1/PD-L1 pathway not only promotes progression of myeloma indirectly by causing failure of immune control but that BM stromal cells induce expression of PD-L1 on myeloma cells, which results in increased proliferation of the tumor cells and dampened susceptibility to anti-myeloma chemotherapy. Accordingly, clinical progression was observed in patients whose myeloma cells expressed high levels of PD-L1.13In conclusion, we have shown here in a large collection of patients with PC dyscrasias including MM that the immunomodulatory molecule PD-L1 is commonly and broadly expressed on the patients' PCs. This and our observation that PD-L1 shows an increased expression on those myeloma cells with an aberrant phenotype suggests an important function of this molecule in suppressing local immunity in the tumor microenvironment of MM. Indeed, it has been shown that myeloma cells overexpressing PD-L1 inhibit the generation of cytotoxic T cells 14 would support the initiation of clinical trials investigating the efficacy of anti-PD-1 or -PD-L1 antibody treatment in MM either alone or in combination, for example, with lenalidomide.15 In addition to indirectly targeting MM by reversing local immunosuppression through anti-PD-1/PD-L1 antibody treatment one could also imagine to directly target PD-L1 expressed on the myeloma cells, for example, by the adoptive transfer of PD-L1-specific chimeric antigen receptor-transduced T cells. As we have shown here, PD-L1 is also expressed on myeloma-propagating pre-PCs and, accordingly, immunotherapeutic approaches directly targeting this surface molecule would have the potential to eradicate chemotherapy-resistant disease. It remains to be determined whether the expression of PD-L1 on normal PCs, as demonstrated in our current study, represents an obstacle to approaches like this.These combined data and the observation made by others that the expression of the PD-L1 receptor PD-1 is upregulated on T cells isolated from patients with MM,SY performed the research, performed the statistical analysis, analyzed and interpreted the data, and wrote the manuscript; JM performed the research; MS collected the data; AL collected the data; TK collected the data; MB performed the research; NK collected the data and contributed vital new reagents or analytical tools; TL wrote the manuscript, DA designed the research, performed the statistical analysis, analyzed and interpreted the data, and wrote the manuscript.


There are errors in the ninth and tenth sentences of the Abstract. These sentences should read: Also there was a decrease in the risk of progression (RR of PFS: 0.82 IC 0.73–0.92) compared to placebo. Conclusions: We observed significant differences in physiologic and clinically relevant outcomes such as reduction in all-cause mortality, IPF related mortality, worsening of IPF and improvement of PFS. So pirfenidone treatment should be considered not only for its benefits in pulmonary function tests but also by its clinically relevant outcomes.There are multiple errors in the Results described below.The third and fourth sentences of the “Progression-free Survival (PFS)” section should read: The meta-analysis includes 786 patients in intervention group and 728 in placebo group . PirfeniThe third sentence of the “Worsening of IPF” section should read: The meta-analysis includes 858 patients in intervention group and 763 in placebo group . Pirfenidone improves worsening of IPF with a RR of 0.64  compared to placebo.The second sentence of the “Adverse events” section should read: The meta-analysis includes 859 patients in intervention group and 763 in placebo group .There is an error in the third sentence of the fourth paragraph of the Discussion. It should read: We also observed differences in clinically relevant outcomes such as reduction in all-cause mortality, IPF related mortality, worsening of IPF and risk of progression; but no benefit on acute exacerbation of IPF.There are errors in the fourth and fifth columns of


The moist cell and the dry cell on the antenna of the male honeybee were exposed to humidities slowly rising and falling at rates between –1.5%/s and +1.5%/s and at varying amplitudes in the 10 to 90% humidity range. The two cells respond to these slow humidity oscillations with oscillations in impulse frequency which depend not only on instantaneous humidity but also on the rate with which humidity changes. The impulse frequency of each cell was plotted as a function of these two parameters and regression planes were fitted to the data points of single oscillation periods. The regression slopes, which estimate sensitivity, rose with the amplitude of humidity oscillations. During large-amplitude oscillations, moist and dry cell sensitivity for instantaneous humidity and its rate of change was high. During small-amplitude oscillations, their sensitivity for both parameters was low, less exactly reflecting humidity fluctuations. Nothing is known about the spatial and temporal humidity variations a honeybee may encounter when flying through natural environments. Microclimatic parameters  were measured from an automobile traveling through different landscapes of Lower Austria. Landscape type affected extremes and mean values of humidity. Differences between peaks and troughs of humidity fluctuations were generally smaller in open grassy fields or deciduous forests than in edge habitats or forest openings. Overall, fluctuation amplitudes were small. In this part of the stimulus range, hygroreceptor sensitivity is not optimal for encoding instantaneous humidity and the rate of humidity change. It seems that honeybee's hygroreceptors are specialized for detecting large-amplitude fluctuations that are relevant for a specific behavior, namely, maintaining a sufficiently stable state of water balance. The results suggest that optimal sensitivity of both hygroreceptors is shaped not only by humidity oscillation amplitudes but also according to their impact on behavior. Hygroreceptors provide an insect with background information such as the direction and rate with which atmospheric humidity is changing. This information contributes significantly to the insect's ability to maintain a stable water balance by avoiding dangerous and preferring favorable humidities. Electrophysiological identification of hygroreceptors has been successfully accomplished in only few species In earlier studies, humidity changes were produced by switching rapidly from one conditioning air stream at a constant humidity to a second at a different constant humidity Understanding the function of hygroreceptors requires knowledge of the adequate stimulus. The relative humidity is obviously the most familiar and practical way of measuring atmospheric humidity and defining the content of water of hygroscopic materials. The water content of a human or horse hair under tension changes its length due to changes in the relative humidity of the air. Accordingly, it was assumed that the sensillum wall acts as a hygro-mechanical transducer which changes its dimension due to the uptake (adsorption) and loss (desorption) of water, much like a hair hygrometer depending on changes in relative humidity Regardless of how the process of humidity transduction is best described, the most important function of insect hygroreceptors is to acquire information about changes in atmospheric humidity. Hygroreceptors represent two input parameters (instantaneous humidity and its rate of change) with a single output parameter (impulse frequency) We chose to study the dynamic sensitivity of the moist and dry cells in the male honeybee. The moist and dry cells of the honeybee offer advantages. They occur together in peg-shaped sensilla located in heavily walled pits which are readily found on worker bee and drone antennae  and someOur knowledge of the properties of humidity stimuli occurring in the insect's natural environment is limited to stationary measurements. Nothing is known about the amplitudes and rates of humidity changes a flying insect may encounter in its natural environment. Plausible ranges of humidity fluctuations could be measured from an automobile traveling with constant speed through different landscapes. Such measurements would indicate what temporal humidity profiles may hit the hygroreceptors of a flying insect. Normal worker bee flight speed is about 7.1 to 8.2 m/s  for unobstructed humidity stimulation. The hygro-thermoreceptive sensilla  was calculated from running averages of three consecutive 0.5-s intervals.Impulse frequency , water vapor density was measured at a rate of 100 Hz. The voltage outputs of the hygrometer and the thermistor were passed through the AD-converter , fed into the PC and recorded online. Based on the digitized signals of the hygrometer and the thermistor, the water vapor pressure (Pw) and the relative humidity (rH) were monitored offline. The saturation water vapor (Ps) and the saturation deficit (SD) were determined offline by running a self-written script.Air from a pressure-regulated source was cleaned, dried and split into two streams. Their flow rates were equalized by matching the rates in mass flow meters. The first stream was bubbled out through many openings in a polyethylene tube firmly anchored in a tank containing ion-exchange purified water at constant depth and at 42°C. The second stream was conducted through the tank in a spiral tube and remained dry as it was warmed to 42°C. The temperature of the two streams was then set at different temperature levels by driving them through a further self-made, thermostatically controlled heat exchanger. After emerging from the heat exchanger, the two air streams passed through electrical proportional valves  and then were combined to a single stream. The water vapor pressure of this stream was sinusoidally modulated by mixing the two streams in a ratio determined by the proportional valves. To hold the flow rate of the mixed air constant at 2.5 m/s, the control voltages  of the proportional valves were phase shifted by 180°. The mixed air was divided into two streams. For stimulation, the first stream was directed towards the antenna by way of a Plexiglas tube 7 mm in diameter. The hygroreceptive sensillum was 5 mm away from the outlet of the tube. The temperature within the air stream was measured within ±0.03°C by a small thermistor  3 mm downstream from the sensillum. By passing the second air stream through a 1-cmAir humidity was measured by an UV krypton absorption hygrometer at a rate of 100 Hz , ambient temperature in real time by a fine-wire thermocouple , and wind speed in real time by a hot wire anemometer. These sensors were installed at the front end of a 4-m rod that was mounted with its back end on the leading edge of the roof rack of an automobile so that it juts out on the right side. In this way, data were collected at a height of 1.5 m above the ground and more than 3 m within the roadside vegetation. The safety distance of more than 5 m minimized the influence of the exhaust fumes. The voltage outputs of the sensors were displayed on an oscilloscope inside the automobile and recorded on a DAT-recorder. In the laboratory, the data were passed through a CED 1401-micro  interface, stored on a hard disc of a PC and analyzed using the commercial software Spike2.Measurement trips lasting 1.5 to 2 h were made in the countryside of Lower Austria  on calm days in June and July during late morning and early afternoon. The sky was generally clear, with some scattered clouds. The automobile travelled at a mean speed of 25 km/h (7 m/s) along vegetated roadsides, open farm fields, grasslands with clusters of trees shadowing the ground, and edge habitats. Deciduous forests with low canopy cover were also crossed. The trips were continuous with no stops or road intersections. No specific permissions were required for the measurement trips in these landscapes. The field studies did not involve endangered or protected species.The basic measures chosen to characterize the temporal profiles of temperature, humidity and wind speed were the amplitudes and positions of the peaks and troughs, and the values of the rising and falling slopes . Peaks aIn both worker bees and drones, the hygroreceptive sensilla are located at the mid region of most antennal segments. Their external structure is shaped like a mushroom with a slightly dilated cap. They are positioned in the central opening of shallow cuticular depressions so that only the cap is visible from outside A. An elThe same antagonistic responses of the two cell types to an increase or decrease in the relative humidity can also be elicited by changing the air temperature. For example, a sudden increase by 4.5°C from 26.4 to 30.9°C F at a crH between 20 and 70% rH was covered and the rates of humidity change were between –2% rH/s and +2% rH/s. In the moist cell, impulse frequency varied between values of 5 and 30 imp/s , and in the dry cell between 22 and 50 imp/s . Impulse frequency of the moist cell tended to be higher at the higher values of instantaneous humidity and lower at the lower values . Conversely, impulse frequency of the dry cell tended to be higher at the lower values of instantaneous humidity and lower at the higher values . Frequency values during humidity oscillations may simply be interpreted as the response to instantaneous humidity, i.e., the succession of humidities at particular instants in time. Impulse frequency, however, is not in step with instantaneous humidity but ahead of it. A second stimulus parameter that is also in advance of instantaneous humidity must influence their responses. The rate of humidity change was the obvious candidate. To estimate the double dependence on instantaneous humidity and its rate of humidity change, the impulse frequency of the moist and dry cells was plotted in Ba and Bb as a function of both parameters.Three kinds of experiments were performed involving slowly changing humidity. In the first kind a humidity amplitude of roughly 50% 30 imp/s Aa,g, a50 imp/s Ab,g. Ir values Aa,c. Cr values Ab,c. FF = a+b drH/dt+c rH; where F is the impulse frequency and a the height of the regression plane) were calculated to determine the simultaneous effects of the rate of humidity change (b slope) and the instantaneous relative humidity (c slope) on the response frequency of both cell types . The slopes demonstrate the two properties that characterize each cell: the sign of the slopes is positive for the moist cell and negative for the dry cell; that is, an increase in both instantaneous humidity and its rate of change raises the impulse frequency of the moist cell and lowers that of the dry cell; and the slopes are similar for the moist and the dry cells, sign ignored. Accordingly, given changes in instantaneous humidity or in the rate of humidity change have similar effects on the frequency of the moist and the dry cell with due consideration of the sign.Multiple regressions  show a strong relationship between impulse frequency, instantaneous humidity and rate of humidity change. For the moist cell, 2R indicates that in a series of oscillating humidity changes, an average of 97% of the variation in impulse frequency can be explained by a multiple regression; for the cold cell, the value is 96%. The orderly relationships of impulse frequency to the instantaneous humidity and its rate of change in both cells provide an opportunity to determine their differential sensitivity. The differential-sensitivity values are the expression of the mean change in impulse frequency for each unit change in stimulus magnitude. On average, differential sensitivity to instantaneous humidity was +0.3 imp/s per % rH for the moist cell and – 0.4 imp/s per % rH for the dry cell; differential sensitivity to the rate of humidity change was +5.2 imp/s per % rH/s for the former and –5.4 imp/s per % rH/s for the latter. Thus impulse frequency of both cells can be influenced more by changing the rate of humidity change by 1% rH/s than by changing instantaneous humidity by one additional percent. Actual measurements show that an increase of 1 imp/s in the moist cell can be elicited either by a +3.3% rH increase in instantaneous humidity (at constant rate of change), or by a +0.19% rH/s rate of humidity change. In the dry cell, it takes a decrease of –2.5% rH in instantaneous humidity – or a rate of change of –0.18% rH/s – to increase frequency by 1 imp/s. Both cells display similar response properties, with due consideration of sign: both are more sensitive to the rate of humidity change than to the humidity at which the change takes place.The mean values of the instantaneous relative humidity and the rate of humidity change from 12 moist and dry cells are listed in rH between 15 and 45% rH were produced. The rate of humidity change lay between –1.5% rH/s and +1.5% rH/s , that of the dry-cell between 5 and 30 imp/s . The time course of impulse frequency of both cell types displayed small irregularities. In the moist cell, the higher impulse frequency values were associated with higher humidity , and in the dry cell with the lower humidity . In order to determine the extent to which the impulse frequencies are governed by instantaneous humidity and the rate of humidity change, the frequency values were plotted as functions of both humidity parameters . The emerging coefficients of determination (2R) indicate that, in a series of oscillating humidity changes, an average of 76% of the variation in the moist-cell' impulse frequency can be explained by a multiple regression; in the dry cell the value is 88%. Thus the mean b slope of +0.5 imp/s per % rH/s for the moist cell and – 0.8 imp/s per % rH/s for the dry cell drawn from all multiple regression provides an estimate for their sensitivity to the rate of humidity change. The mean c slope of +0.2 imp/s per % rH for the moist cell and –0.2 imp/s per % rH for the dry cell estimates their sensitivity to instantaneous humidity. To produce an average increase of 1 imp/s in the moist cell, instantaneous humidity must increase by +5% rH or the rate of change by +2% rH/s. The corresponding dry cell values are either a decrease in instantaneous humidity of –5% rH or a decrease in the rate of change of –1.2% rH/s. Thus the dry cell is more sensitive to both humidity parameters.In the second experiment, slow humidity changes covering a range of roughly 30% .5% rH/s B. Moist.5% rH/s Aa,g, t30 imp/s Ab,g. Thumidity Aa,g, ahumidity Ab,g. Irameters Ba,b. TrH between 10 and 20% rH. The rate of humidity change was between –1.5% rH/s and +1.5% rH/s , in the dry cell from 5 to 15 imp/s . Plotting the impulse frequency of both cells as a function of instantaneous humidity and its rate of change yielded flat regression planes . For the moist cell, 2R indicates that, in a series of oscillating humidity changes, an average of only 12% of the variation in impulse frequency can be explained by a multiple regression; for the dry cell, the value was 14%. Thus, both cells are only slightly affected by humidity changes, if at all.In the third experiment, the humidity changes covered roughly 10% .5% rH/s C. In th.5% rH/s Aa,g, i15 imp/s Ab,g. Pn planes Ba,b. Fi) open farm fields and areas of short grass with clusters of trees shadowing the ground (ii) through deciduous forests with low canopy cover (iii) through fragmented forests with transitions (edges) to grasslands with ruderals and other herbs . Habitat affected the extremes of humidity peaks and troughs as well as the mean values. Specifically, the humidity transitions were more round and smooth in open grassy fields  than in deciduous forests (a.b.c), but they were abrupt in edge habitats . In open grassy fields, light winds were interspersed with brief periods during which wind speed fluctuated or remained broadly stable at a new level (d). Air temperature was relatively constant (e). In fragmented deciduous forests, however, rapid changes in wind speed were evident, and the rate at which peaks occurred ranged considerably (d). Temperature tended to fluctuate constantly rather than peak (e). Crossing the edges of a fragmented habitat yielded rapid changes in wind speed with multiple peaks (d). In the same situation, temperature changed quickly and fluctuated around a new value (e). A comparison of the temporal profiles of the parameters measured in different landscapes revealed that the absolute humidity  affects the relative humidity (a) and the saturation deficit (––Cb) more than it does the temperature (e) or wind speed (d).These experiments center on the questions of what kind of humidity stimuli a honey bee may encounter during long-distance flights. We made 25 measurement trips using an automobile that traveled along vegetated roadsides, passing  py cover B, and . Moreover, when the absolute humidity is high, the peaks and the troughs are also high, and when the absolute humidity is low, the peaks and troughs are also low. The almost parallel slopes of the regression lines used to approximate the dependences of the peaks and troughs of the relative humidity and the saturation deficit on the absolute humidity indicate that the fluctuation amplitudes are almost the same at different absolute humidities. By contrast to the absolute humidity, the peak and trough of the relative humidity were affected neither by temperature  nor wind speed . Similarly, the peak values of the saturation deficit display no dependence on temperature or wind speed. However, the trough values of the saturation deficit slightly decrease with increasing temperature.The temporal profiles in .8% rH/s . The ratperature Ab,Bb nnd speed Ac,Bc. In his study of the cockroach's hygroreceptors, Yokohari (1978) suggested that hygroreceptors function as mechanical hygrometers. He provided a descriptive model based on the assumption that the cuticular wall of the sensillum acts as a hygro-mechanical transducer that changes its dimension due to the uptake (adsorption) and loss (desorption) of water like a hair hygrometer. This water uptake detector functions because a human or horse hair under tension becomes longer when the relative humidity rises and shorter when it falls. It became accepted wisdom that relative humidity is the adequate stimulus. However, the relative humidity is not a direct measure of the water vapor in the air. Identical relative humidity values do not indicate identical atmospheric moisture conditions unless the temperature is also the same. A 50% relative humidity at low temperatures contains much less water vapor than a 50% relative humidity at high temperatures. The reason is that the higher the temperature, the more thermal energy is in the air and the more evaporative work can be done in that air parcel. Evaporation will therefore occur more rapidly from a moist surface (under the same conditions) into an air with a relative humidity of 50% at high than at low temperature. The relative humidity of the air alone does not indicate the moisture conditions of the air. An air parcel with a 50% relative humidity is dry when the temperature is high but wet when the temperature is low: 50% relative humidity indicates dryness at high temperatures or wetness at low temperatures. Relative humidity is a useful measure of evaporation provided that moisture conditions are being assessed at a single constant temperature. Thus if an insect defends its water content by keeping evaporation constant, it must maintain a constant vapor pressure deficit and search for regions of similar saturation deficit. To maintain the same saturation deficit at high temperatures, the relative humidity must be increased and vice versa. If observations are to be extended over a range of temperatures, however, the saturation deficit is the exact measure. For this reason we recorded the water vapor pressure, the saturation deficit as well as the relative humidity. However, nothing is known about the amplitudes and rates of both humidity and temperature changes encountered by a running or flying insect in its natural environment. In this study we addressed these issues by mobile measurements of the fluctuating strength of humidity and temperature in different landscapes.Mobile humidity measurements from an automobile have the disadvantage of being confined to passable landscapes. Nonetheless, the measurements can be made representative very easily by repeating a trip so that humidity values at different times or weather conditions can be quantified for given landscapes; the common evaluation method facilitates data interpretation. Importantly, this study did not attempt to characterize the microclimatic conditions of various landscapes. The potential effects of landscape structures such as topography, slope and aspect, or composition, density and heights of vegetation were not considered. Moreover, the measurements were done on calm and clear summer days, which are no doubt the most suitable for bee flight activity.The important finding was that the dominant form of changes in the absolute humidity was slow, regardless of landscape type. Accordingly, the rates of changes in relative humidity and the saturation deficit were low. The landscapes, however, differ in the range and amplitude of humidity changes. In contrast, the temperature changes were small in the different landscapes; similarly small was their effect on the humidity peak and trough values, regardless of how humidity was expressed. Wind speed generally changed more pronouncedly than temperature but without affecting the humidity peaks or troughs.rH) and then stimulated with higher humidity levels up to saturated air. Conversely, the dry cell was adapted to extremely moist air (100% rH) and then stimulated with lower humidity levels down to dry air. In the moist cell, impulse frequency was higher the higher the humidity level used for stimulation, and conversely, the dry-cell's impulse frequency was higher the lower the stimulating humidity level. Nonetheless, the technique used to stimulate the worker-bee's hygroreceptors requires comment The first recordings from a single sensillum containing a hygroreceptor were reported by Lacher (1964) 50 years ago. He identified a moist cell on the antenna of the worker bee. Waldow (1970) demonstrated electrophysiologically on the antenna of the locust a dry cell together with a moist cell in the same sensillum. Yokohari et al. (1983) reinvestigated the worker-bee's hygroreceptive sensilla and found a moist cell and a dry cell combined in a single sensillum with a cold cell. Stimulation consisted of rapid, step-like changes in relative humidity. To this end, the moist cell was adapted to extremely dry air (0% rH), a 1 imp/s increase in the moist-cell's discharge can be elicited by increasing instantaneous humidity by +3.3%. In the same situation, it takes a –2.5% decrease to increase frequency of the dry cell by 1 imp/s. When the oscillation amplitude is reduced to a medium value (∼30% rH), it takes in the moist cell a +5% increase in instantaneous humidity for a 1 imp/s increase; in the dry cell the value is –5%. A further reduction of the oscillation amplitude to a small value (∼10% rH) requires even larger humidity changes to affect the discharge rates of the two cells by the same amount.The range over which humidity oscillated determined the response magnitude of the moist and dry cells as well as their sensitivity. This magnitude decreased with diminishing oscillation amplitude. In effect, they responded well to large and poorly to small amplitude oscillations. In accordance with the responsiveness, sensitivity decreased with diminishing oscillation amplitude. Sensitivity is usually described by the reciprocals of the slope values of the input-output functions, i.e., the increment in stimulus strength required to change impulse frequency by 1 imp/s. Insects are believed to regulate their water content by avoiding areas with extremes and by moving along the humidity gradient into a more suitable environment. While avoidance or search behavior is certainly very efficient in dealing with the insect's water balance, it has the disadvantage that the insect's entire activity is devoted to improving its humidity environment. It therefore competes with other forms of behavior and its presence at a given time means that humidity is at that time the most important motivation for the insect. In trying to understand the contribution of hygroreceptors to specific behaviors, the responses of the moist and dry cells were plotted as functions of the instantaneous humidity and its rate of change. The range of impulse frequency spanned by the regression planes and their slopes indicate hygroreceptor sensitivity. High values are much more likely to lead to behavioral responses than low ones. Reduction in sensitivity suggests, but does not strictly demonstrate, a decrease in information content.In the honeybee's hygroreceptors, high sensitivity is devoted to large-amplitude humidity oscillations, which may seriously affect body water content. Small-amplitude oscillations are associated with low sensitivity, probably because they are less harmful. Accordingly, sensitivity is related not only to the hygroreceptors' inputs but also to the outputs relevant for the specific behavior of improving water balance. Low-amplitude oscillations will be relevant too if they occur in the range of extreme humidities but they may be of little use for orientation as the stimulus field has no definite directions. However, some insect tolerate extremes of their water content and finally carry out escape movements intended to improve the humidity environment.