Pesticide residues in Tunisian table grapes and associated risk for consumer's health.

Sixty-four table grape samples from different regions of Tunisia were collected during three consecutive years (2015-2017). The presence of 96 pesticides, including dithiocarbamates, was assessed. Pesticides identification and quantification were performed by liquid or gas chromatography, coupled to tandem mass spectrometry. All samples contained multiple residues (4 to 24 residues), with an average of 11.6 residues per sample. Individual concentrations of pesticides in grapes ranged from 0.01 to 5.86 mg kg-1. For at least one chemical compound, exceedances of the European Maximum Residue Limits were found in 94% of the samples. To assess the potential risk of pesticides through consumption of grapes, the acute exposure was estimated by the determination of predicted short term intake which is expressed as a percentage of Acute Reference Dose (ARfD), for non-compliances of pesticides. The exceedance of ARfD was associated with carbofuran, carbendazim, chlorpyrifos, deltamethrin, dimethoate and omethoate. Consequently, these pesticides could present a risk for consumer's health.

Design and control of multi-actuated atomic force microscope for large-range and high-speed imaging.

This paper presents the design and control of a high-speed and large-range atomic force microscopy (AFM). A multi-actuation scheme is proposed where several nano-positioners cooperate to achieve the range and speed requirements. A simple data-based control design methodology is presented to effectively operate the AFM scanner components. The proposed controllers compensate for the coupled dynamics and divide the positioning responsibilities between the scanner components. As a result, the multi-actuated scanner behavior is equivalent to that of a single X-Y-Z positioner with large range and high speed. The scanner of the designed AFM is composed of five nano-positioners, features 6 µm out-of-plane and 120 µm lateral ranges and is capable of high-speed operation. The presented AFM has a modular design with laser spot size of 3.5 µm suitable for small cantilever, an optical view of the sample and probe, a conveniently large waterproof sample stage and a 20 MHz data throughput for high resolution image acquisition at high imaging speeds. This AFM is used to visualize etching of calcite in a solution of sulfuric acid. Layer-by-layer dissolution and pit formation along the crystalline lines in a low pH environment is observed in real time.

Multi-actuation and PI control: a simple recipe for high-speed and large-range atomic force microscopy.

High speed atomic force microscopy enables observation of dynamic nano-scale processes. However, maintaining a minimal interaction force between the sample and the probe is challenging at high speed specially when using conventional piezo-tubes. While rigid AFM scanners are operational at high speeds with the drawback of reduced tracking range, multi-actuation schemes have shown potential for high-speed and large-range imaging. Here we present a method to seamlessly incorporate additional actuators into conventional AFMs. The equivalent behavior of the resulting multi-actuated setup resembles that of a single high-speed and large-range actuator with maximally flat frequency response. To achieve this, the dynamics of the individual actuators and their couplings are treated through a simple control scheme. Upon the implementation of the proposed technique, commonly used PI controllers are able to meet the requirements of high-speed imaging. This forms an ideal platform for retroactive enhancement of existing AFMs with minimal cost and without compromise on the tracking range. A conventional AFM with tube scanner is retroactively enhanced through the proposed method and shows an order of magnitude improvement in closed loop bandwidth performance while maintaining large range. The effectiveness of the method is demonstrated on various types of samples imaged in contact and tapping modes, in air and in liquid.

Compensator design for improved counterbalancing in high speed atomic force microscopy.

High speed atomic force microscopy can provide the possibility of many new scientific observations and applications ranging from nano-manufacturing to the study of biological processes. However, the limited imaging speed has been an imperative drawback of the atomic force microscopes. One of the main reasons behind this limitation is the excitation of the AFM dynamics at high scan speeds, severely undermining the reliability of the acquired images. In this research, we propose a piezo based, feedforward controlled, counter actuation mechanism to compensate for the excited out-of-plane scanner dynamics. For this purpose, the AFM controller output is properly filtered via a linear compensator and then applied to a counter actuating piezo. An effective algorithm for estimating the compensator parameters is developed. The information required for compensator design is extracted from the cantilever deflection signal, hence eliminating the need for any additional sensors. The proposed approach is implemented and experimentally evaluated on the dynamic response of a custom made AFM. It is further assessed by comparing the imaging performance of the AFM with and without the application of the proposed technique and in comparison with the conventional counterbalancing methodology. The experimental results substantiate the effectiveness of the method in significantly improving the imaging performance of AFM at high scan speeds.

Indirect identification and compensation of lateral scanner resonances in atomic force microscopes.

Improving the imaging speed of atomic force microscopy (AFM) requires accurate nanopositioning at high speeds. However, high speed operation excites resonances in the AFM's mechanical scanner that can distort the image, and therefore typical users of commercial AFMs elect to operate microscopes at speeds below which scanner resonances are observed. Although traditional robust feedforward controllers and input shaping have proven effective at minimizing the influence of scanner distortions, the lack of direct measurement and use of model-based controllers have required disassembling the microscope to access lateral scanner motion with external sensors in order to perform a full system identification experiment, which places excessive demands on routine microscope operators. Further, since the lightly damped instrument dynamics often change from experiment to experiment, model-based controllers designed from offline system identification experiments must trade off high speed performance for robustness to modeling errors. This work represents a new way to automatically characterize the lateral scanner dynamics without addition of lateral sensors, and shape the commanded input signals in such a way that disturbing dynamics are not excited. Scanner coupling between the lateral and out-of-plane directions is exploited and used to build a minimal model of the scanner that is also sufficient to describe the nature of the distorting resonances. This model informs the design of an online input shaper used to suppress spectral components of the high speed command signals. The method presented is distinct from alternative approaches in that neither an information-complete system identification experiment nor microscope modification are required. Because the system identification is performed online immediately before imaging, no tradeoff of performance is required. This approach has enabled an increase in the scan rates of unmodified commercial AFMs from 1-4 lines s(-1) to over 40 lines s(-1).

Use of self-actuating and self-sensing cantilevers for imaging biological samples in fluid.

In this paper, we present a detailed investigation into the suitability of atomic force microscopy (AFM) cantilevers with integrated deflection sensor and micro-actuator for imaging of soft biological samples in fluid. The Si cantilevers are actuated using a micro-heater at the bottom end of the cantilever. Sensing is achieved through p-doped resistors connected in a Wheatstone bridge. We investigated the influence of the water on the cantilever dynamics, the actuation and the sensing mechanisms, as well as the crosstalk between sensing and actuation. Successful imaging of yeast cells in water using the integrated sensor and actuator shows the potential of the combination of this actuation and sensing method. This constitutes a major step towards the automation and miniaturization required to establish AFM in routine biomedical diagnostics and in vivo applications.

[Interference of ethylene glycol on lactate assays]. / Interférences des métabolites de l'éthylène glycol avec les dosages du lactate.

Ethylene glycol is broken down to three main organic acids: glycolic acid, glyoxylic acid and oxalic acid which cause severe metabolic acidosis. Effect of these three acids on lactate assays was evaluated in five blood gas analysers and two clinical chemistry analysers. For all systems, no influence of oxalic acid on lactate results could be demonstrated. No interference of glycolic acid could be observed on lactate assay performed with Rapid Lab 1265 (R: 104,9 +/- 12,1%), Vitros 950 (R: 105,7 +/- 5,3 %) and Architect ci8200 (R: 104,9 +/- 4,7%), but on the contrary, CCX 4, OMNI S, ABL 725 and 825 demonstrated a concentration-dependent interference. No interference of glyoxylic acid could be observed with Vitros 950, but a positive interference could be observed with ABL 725 and 825, OMNI S, CCX4 and Architect ci8200 A linear relationship between apparent lactate concentration found with ABL 725 and 825, OMNI S, CCX 4, and glyoxylic acid could be observed (0,94 < r < 0,99), a weaker interference being observed with Rapid Lab 1265 and Architect ci 8200. Our results demonstrated that in case of ethylene glycol poisoning, cautious interpretation of lactate assay should be done, since wrong results of lactacidemia could lead to misdiagnostic and delay patient treatment.

[Arteriovenous aneurysm of the corpus callosum with normal arteriography 9 years earlier]. / Anévrysme artério-veineux du corps calleux avec artériographie normale 9 ans auparavant.

Some arteriovenous malformations (A.V.M.s) visualized on a first angiography tend to enlarge gradually with time. Others A.V.M.s may decrease in size and even disappear. The authors report the case of a 18 year old woman admitted for a subarachnoid hemorrhage. A complete cerebral angiography was normal. Nine years later, an arteriovenous malformation of the corpus callosum was discovered. The reasons why angiography may fail to demonstrate an A.V.M., and the theories concerning the enlargement of A.V.M.S., are discussed.

[Anterior ethmoidal dural fistulae. 3 new cases]. / Fistules durales ethmoïdales antérieures. Trois nouvelles observations.

The authors report three new cases of anterior ethmoidal dural fistulae: a pure pial and two dural and pial fistulae which presented in the form of rupture. The emphasise the computed tomographic features, revealing a unilateral frontopolar haematoma and the need for angiographic assessment including study of the internal and external carotid arteries. Carotid angiography of the fistula defines the therapeutic modalities which are generally surgical.

Interhemispheric subdural haematomas: seven cases and review of the literature.

Interhemispheric subdural haematoma (ISH) is a rare complication of head injury with only 19 cases reported since 1940, but it may also occur spontaneously (three cases). In both circumstances, clotting disorders are frequent (six cases). We have recorded seven cases (five traumatic, two spontaneous). Classically ISH is due to tearing of bridging veins or cortical contusions. In one of our cases, it was due to arterial bleeding from a pericallosal branch. CT scan shows that ISH may extend above the tentorium and on the hemispheric convexity. Mortality is high (35%). The best operative procedure is parasagittal craniotomy. Chronic interhemispheric subdural haematomas also occur.

[Is it necessary to operate on asymptomatic aneurysms? Apropos of 114 surgically treated asymptomatic aneurysms]. / Faut-il opérer les anévrysmes asymptomatiques? A propos de 114 anévrysmes asymptomatiques opérés.

A six years retrospective analysis of asymptomatic aneurysms (A.A.) was done in 4 neurosurgical departments: 114 AA were clipped in 99 patients. In 44 patients (48 asymptomatic aneurysms) the surgical procedure was achieved in one step for both symptomatic and asymptomatic aneurysms. In 59 patients (66 asymptomatic aneurysms) the surgical procedure was delayed as it necessitated a second and elective craniotomy. As regard the treatment of asymptomatic aneurysms, there was no morbidity, and one death due to a massive pulmonary embolism. These surgical results are undoubtebly better than the risk of hemorrhage from unruptured aneurysm as emphasized in the literature.

[Surgical findings and results after failure of lumbar chemonucleolysis. 72 cases]. / Constations opératoires et résultats après échec de la chimionucléolyse lombaire. 72 cas.

Seventy two patients undergoing lumbar chemonucleolysis (LCN) involving one (49 cases) or two (23 cases) discs underwent surgery after failure of the procedure. In 5 cases the disc prolapse responsible for the recurrence of pain was at a different site from that of the LCN. Analysis of true failures in the light of operative findings showed that the presence of a migrated disc sequestrum at a distance from the space injected was rare (7% of cases). By contrast, the discovery of a true sub-ligamentous disc prolapse was common (32%). In 1/3 of cases these prolapses contained actual intra-discal sequestra within a scanty amount of basic substance, as if the enzyme had destroyed the latter but had no action upon the former. Simple disc protrusions were discovered in 36% of cases, combined in one case out of five with stenosis of a lateral recess. Finally, in 25% of cases the disc explored was flat, combined in 1 case out of 3 with a considerable inflammatory reaction. The percentage of good and very good operative results was 60.7% overall, rising to 70% taking into consideration only those patients undergoing LCN at one level only. The authors feel that no longer than a month should be allowed to pass before deciding to operate after failure of LCN.

[Early surgery of ruptured aneurysms. A factor in preventing ischemia]. / L'opération précoce des anévrysmes rompus. Un facteur de prévention de l'ischémie.

110 patients with ruptured aneurysms were operated on within 4 to 96 hours after subarachnoid hemorrhage. Clinical grades (Hunt) were: 1-2-3 in 93 cases and 4-5 in 17 cases. Among the patients grades 1-2-3, 81% had a good out come without any neurological abnormality, among the patients graded 4-5, only 27% had a fair out come. Cerebral ischemia has been noted (CTS can + neurological deficits) in 7 cases only among patients graded 1-2-3 (93 cases). The results, concerning ischemia, are better than the natural course of ruptured aneurysms and better than the course in series with delayed operation. Probably vasospasm is not alone to create ischemia.

Furosemide and bumetanide-sensitive Na+ fluxes in erythrocytes from genetically hypertensive rats (SHR).

Na+ and K+ fluxes from erythrocytes of SHR and WKY control rats have been studied. Fluxes were measured in both fresh and sodium-loaded (after exposure to ouabain or PCMBS) erythrocytes. Pump activity appears higher and furosemide or bumetanide sensitive Na+ efflux lower in SHR compared to WKY suggesting a similar abnormality in SHR genetic hypertension as in human hypertension.