Cellular architecture of the testis of Egyptian wild boar (Sus scrofa) in young and adult age

Testicular parenchyma is split into lobules, each lobule contains convoluted seminiferous tubules surrounded by myoid cells and the interstitial tissue contains groups of Leydig cells. The seminiferous tubules are lined by two groups of cells the first one is the spermatogenic cells and the second one is Sertoli cells.     

On the reliability of electrostatic NEMS/MEMS devices: Review of present knowledge on the dielectric charging and stiction failure mechanisms and novel characterization methodologies

This paper reviews the state of the art knowledge related to critical failure mechanisms in electrostatic micro- and nano-electromechanical systems (MEMS and NEMS) which are the dielectric charging and stiction. It describes also the recent employed nanoscale characterization techniques for these phenomena based on Kelvin probe force microscopy (KPFM) and force–distance curve measurements. The influence of relative humidity and dielectric deposition conditions on the charging/discharging processes is discussed. Moreover, different stiction mechanisms induced by electrostatic force and/or meniscus formation are analyzed. Finally, novel characterization methods are presented and used to correlate between the results from MEMS devices and metal–insulator–metal (MIM) capacitors. These methods are employed in view of application in electrostatic capacitive MEMS switches and could be easily extended to explore other NEMS/MEMS devices. The study provides an accurate understanding of the charging and stiction related failure mechanisms, presents guidelines for a proper packaging environment, and reveals precise explanations for the literature reported device level measurements of electrostatic MEMS devices.     

On the influence of environment gases, relative humidity and gas purification on dielectric charging/discharging processes in electrostatically driven MEMS/NEMS devices

In this paper, we investigate the impact of environment gases and relative humidity on dielectric charging phenomenon in electrostatically actuated micro- and nano-electromechanical systems (MEMS and NEMS). The research is based on surface potential measurements using Kelvin probe force microscopy (KPFM). Plasma-enhanced chemical vapor deposition (PECVD) silicon nitride films were investigated in view of applications in electrostatic capacitive RF MEMS switches. Charges were injected through the atomic force microscope (AFM) tip, and the induced surface potential was measured using KPFM. Experiments have been performed in air and in nitrogen environments, both under different relative humidity levels ranging from 0.02% to 40%. The impact of oxygen gas and hydrocarbon contaminants has been studied for the first time by using different gas purifiers in both air and nitrogen lines. Voltage pulses with different bias amplitudes have been applied during the charge injection step under all investigated environmental conditions in order to investigate the effect of bias amplitude. The investigation reveals a deeper understanding of charging and discharging processes and could further lead to improved operating environment conditions in order to minimize the dielectric charging. Finally, the nanoscale KPFM results obtained in this study show a good correlation with the device level measurements for capacitive MEMS switches reported in the literature.     

A monolithic CMOS microhotplate-based gas sensor system

A monolithic CMOS microhotplate-based conductance-type gas sensor system is described. A bulk micromachining technique is used to create suspended microhotplate structures that serve as sensing film platforms. The thermal properties of the microhotplates include a 1-ms thermal time constant and a 10/spl deg/C/mW thermal efficiency. The polysilicon used for the microhotplate heater exhibits a temperature coefficient of resistance of 1.067/spl times/10/sup -3///spl deg/C. Tin(IV) oxide and titanium(IV) oxide (SnO/sub 2/,TiO/sub 2/) sensing films are grown over postpatterned gold sensing electrodes on the microhotplate using low-pressure chemical vapor deposition (LPCVD). An array of microhotplate gas sensors with different sensing film properties is fabricated by using a different temperature for each microhotplate during the LPCVD film growth process. Interface circuits are designed and implemented monolithically with the array of microhotplate gas sensors. Bipolar transistors are found to be a good choice for the heater drivers, and MOSFET switches are suitable for addressing the sensing films. An on-chip operational amplifier improves the signal-to-noise ratio and produces a robust output signal. Isothermal responses demonstrate the ability of the sensors to detect different gas molecules over a wide range of concentrations including detection below 100 nanomoles/mole.     

Interleukin 1 increases thymidine labeling index of normal tissues of mice but not the tumor

PURPOSE: This study was conducted to investigate the action of human recombinant interleukin 1 as a radioprotector for different mouse normal cells other than bone marrow cells. METHODS AND MATERIALS: Semi-continuous injections of tritiated thymidine were administered every 6 h, over 24 h to determine thymidine labeling index. Mice were injected with recombinant human interleukin 1 24 h prior to tritiated thymidine and were compared to control animals that did not receive interleukin 1. Mice were killed 1 h after the last thymidine injection. The 24 h thymidine labeling index for normal tissues and RIF-1 tumor was determined. Labeling indices were also determined 1-14 days after a series of fractionated irradiations with or without pretreatment with a single dose of interleukin 1 administered 24 h prior to the first radiation. RESULTS: The thymidine labeling index of normal tissues was higher following the injection of recombinant human interleukin 1 24 h before radiolabeling. This was found in all normal tissues tested, including the lip and tongue mucosal basal cell layers, crypt cells of the duodenum, alveolar cells of the lung, hepatocytes, and basal skin cells. The thymidine labeling index of RIF-1 fibrosarcoma was not affected by interleukin 1 injection. A single interleukin 1 injection 24 h before the first radiation fraction also increased the thymidine labeling indices of normal tissues after localized fractionated irradiation. The thymidine labeling index of RIF-1 tumor was not increased by interleukin 1 administration except after relatively high radiation doses (20 Gy in five fractions). The ability of interleukin 1 to enhance the thymidine labeling index declined after the first day following the completion of fractionated irradiation. CONCLUSION: Recombinant human interleukin 1 increased the 24 h thymidine labeling index in normal tissues in mice, but not in RIF-1 tumor. Fractionated irradiation could maintain the effect of a single dose of interleukin 1, administered 24 h prior to the first fraction, up to 24 h after the end of radiation.     

Determination of pefloxacin and its main active metabolite in human serum by high-performance liquid chromatography

BACKGROUND: Investigation to see if there are key psychological risk indicators for autism in a random population study of children at 18 months of age; and to assess how well these discriminate children who receive a diagnosis of autism from other forms of developmental delay. METHOD: Sixteen thousand children in the southeast of England were screened for autism by their health visitor or GP, during their routine 18-month-old developmental check-up, using the CHAT (Checklist for Autism in Toddlers). From a previous high-risk study we predicted that children at 18 months of age who failed three items ('protodeclarative pointing', 'gaze-monitoring', and 'pretend play') would be at risk for receiving a diagnosis of autism. From other evidence, we further predicted that those 18-month-olds who failed one or two of the key items (either pretend play, or protodeclarative pointing and pretend play) would be at risk for developmental delay without autism. RESULTS: Twelve children out of the total population of 16,000 consistently failed the three key items. Of these, 10 (83.3%) received a diagnosis of autism. Thus, the false positive rate was 16.6% (2 out of 12 cases), and even these 2 cases were not normal. When the 10 children with autism were reassessed at 3.5 years of age, their diagnosis remained the same. Thus the false positive rate among the cases diagnosed with autism was zero. In contrast, of 22 children who consistently failed either protodeclarative pointing and/or pretend play, none received a diagnosis of autism, but 15 (68.2%) received a diagnosis of language delay. CONCLUSIONS: Consistent failure of the three key items from the CHAT at 18 months of age carries an 83.3% risk of autism; and this pattern of risk indicator is specific to autism when compared to other forms of developmental delay.     

A simple method for the evaluation of microwave mixer diodes

A simple method is described for the evaluation of the various microwave mixer diodes which can be used in 9-GHz electron paramagnetic resonance (EPR) spectrometers using magnetic field modulation below 1 kHz. The advantage of this method over other methods is that it is optimized for EPR applications and determines the optimum operating conditions for each microwave diode. This method utilizes a microwave bridge with a reference arm with an attenuator to control the microwave bias power level, and a signal arm where the signal is attenuated, phase shifted, and modulated at the typical magnetic field modulation frequencies. The microwave power from the two arms is recombined and demodulated by the microwave diode. The output of the microwave diode is then recorded with various video loads, microwave bias power, and modulation frequencies. Measurements are performed to determine the effect of the preamplifier that followed the microwave diode on the signal-to-noise ratio (SNR). The recorded spectra are used to determine the SNR, the noise floor, and the 1/f corner frequency. Comparison of these factors for the different types of microwave diodes shows that some Schottky-barrier diodes have noise figures at 1 kHz that are as low as those for tunnel diodes     

Estimation of phase differential of signals transmitted over fading channels

The authors show that it is possible to use the Hilbert transform to estimate the absolute value of the phase differential of signals transmitted over fading channels from the envelope of the signal. This is demonstrated on a mobile radio channel and on an indoor radio channel.<>     

Spectrophotometric and potentiometric studies of chelates formed between some metals and some azo dyes

The chelation of phenylazo derivatives of α-and β-naphthols with Co(II), Ni(II) and Cu(II) compounds have been studied in solution spectrophotometrically, while chelation with Ti(IV), Zr(II)O, Th(IV) and U(II)O2 compounds has been studied potentiometrically. The proton-ligand stability constants, the formation constants and the coordination of the chelates have been determined.     

Design of reflection retarders by use of nonnegative film-substrate systems

A reflection-type film-substrate retarder is an optical device that changes the relative phase but not the relative amplitude of light upon reflection from a film-substrate system. While there are several such device designs based on the common negative film-substrate system, very little has been done with the other two categories of systems, zero and positive. The system category is determine by the relationship between the refractive indices of the ambient N0, film N1 and substrate N2. If N1 < square root of N0N2, the system is negative; if N1 = square root of N0N2, the system is zero; and if N1 > square root of N0N2, the system is positive. The design procedure and characteristics of zero-system reflection retarders are discussed. The polarization and ellipsometric properties of the positive system preclude the existence of a reflection retarder. First, a brief characterization of the zero and positive systems by means of constant-angle-of-incidence contours and constant-thickness contours of the ellipsometric function is presented and discussed. Then an algorithm outlining the design procedures is presented, and the characteristics of the obtained designs are optimized, analyzed, and discussed. The exact retarder is valid for a single wavelength at a set angle of incidence. The design tolerance to changes in the design parameters is analyzed and discussed. In general, N1 < or = square root of N1N2 is the condition to be satisfied to realize reflection-type retarders with film-substrate systems.