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Background Monocytes can differentiate into either proinflammatory, microbicidal M1 macrophage or anti-inflammatory M2 macrophage subtypes. In addition to macrophages, regarding monocyte subsets, M1 monocytes and M2 monocytes mirroring the M1/M2 macrophage polarization concept were suggested. Little is known regarding the relationships between osteoclastogenesis and M1/M2 monocyte subsets. Objectives We investigated the relationships among M1 monocytes, M2 monocytes, osteoclast differentiation ability and clinical characteristics in patients with rheumatoid arthritis (RA). Methods Peripheral blood mononuclear cells (PBMCs) were isolated from RA patients and healthy donors, and we then investigated the number of M1 monocytes or M2 monocytes by fluorescence-activated cell sorting. We defined positive CD14, CD68 and CCR2 monocytes as M1 monocytes, and in separate tubes, we defined positive CD14, CX3CR1 and CD163 or CD206 monocytes as M2 monocytes. We also obtained and cultured CD14-positive cells from PBMCs from RA patients and healthy donors to investigate osteoclast differentiation in vitro. We defined osteoclasts as tartrate-resistant acid phosphatase (TRAP) staining-positive cells with >3 nuclei. We counted the osteoclasts in the whole wells of a 96-well dish. Pit formation assays were performed to evaluate function of osteoclasts. Results Forty RA patients and 20 healthy donors were included. Twenty-two patients (55%) were ACPA-positive. The median M1/M2 ratio was 0.59 (0.31–1.11, IQR). There were no significant differences between the RA patients and healthy donors. There was a positive correlation between the M1/M2 ratio and the differentiated osteoclast number in vitro in RA patients (ρ=0.81, p The ACPA-positive patients had significantly higher M1/M2 ratio in vivo (p=0.028) (E) and significantly greater numbers of osteoclasts in vitro (p Multivariable regression analysis revealed that the M1/M2 ratio was the sole significant contribution factor to in vitro osteoclastogenesis (β-coefficient 16.3, p RA patients with M1/M2 ratio >1 (having relatively more M1 monocytes) had higher erythrocyte sedimentation rates (p=0.011) and C-reactive protein (p=0.032) than RA patients with M1/M2 ratio ≤1. M1-dominant monocytes in vitro produced higher concentrations of IL-6 upon stimulation with lipopolysaccharide than M2 monocytes (p=0.032). Conclusions The M1/M2 ratio is strongly correlated with the in vitro differentiation of osteoclasts in patients with RA. The RA patients with positive ACPA had higher M1/M2 ratio and higher numbers of osteoclasts. M1 and M2 monocyte subsets may become a new target of treatments for RA. Disclosure of Interest None declared

Oral administration of probiotics has been known to improve inflammatory responses against infectious diseases. Here, we describe the inhibitory effect of oral intake of heat-killed Lactobacillus pentosus strain b240 (b240) on pneumococcal pneumonia in a murine experimental model., Letters in Applied Microbiology, 53(1), pp.35-43; 2011

For small pixel, infrared (IR) focal plane arrays (FPAs), Raytheon Vision Systems’ architecture for integrated, dual-band detectors uses the sequential mode of the n-p+-n configuration. There is a single indium bump per pixel, leaving the p+ layer floating, and the operating polarity of the bias selects the spectral sensitivity by reverse-biasing the active p-n junction. Photogenerated minority carriers in the absorber layer of the forward-biased inactive photodiode are lost through recombination. This paper is the first report of a new optical crosstalk mechanism that occurs in sequential-mode, dual-band detectors. In the long-wavelength mode under out-of-band, short-wavelength illumination, radiative recombination yields emission near the bandgap energy of the short-wavelength absorber layer, resulting in a spurious short-wavelength response that appears as spectral crosstalk. We present experimental and device modeling results on the spectral crosstalk in molecular-beam-epitaxy-grown HgCdTe arrays with the cutoff wavelength of both bands in the 4–5-µm range.

Raytheon Vision Systems (RVS, Goleta, CA) in collaboration with HRL Laboratories (Malibu, CA) is contributing to the maturation and manufacturing readiness of third-generation, dual-color, HgCdTe infrared staring focal plane arrays (FPAs). This paper will highlight data from the routine growth and fabrication of 256×256 30-µm unit-cell staring FPAs that provide dual-color detection in the mid-wavelength infrared (MWIR) and long wavelength infrared (LWIR) spectral regions. The FPAs configured for MWIR/MWIR, MWIR/LWIR, and LWIR/LWIR detection are used for target identification, signature recognition, and clutter rejection in a wide variety of space and ground-based applications. Optimized triple-layer heterojunction (TLHJ) device designs and molecular beam epitaxy (MBE) growth using in-situ controls has contributed to individual bands in all dual-color FPA configurations exhibiting high operability (>99%) and both performance and FPA functionality comparable to state-of-the-art, single-color technology. The measured spectral cross talk from out-of-band radiation for either band is also typically less than 10%. An FPA architecture based on a single-mesa, single-indium bump, and sequential-mode operation leverages current single-color processes in production while also providing compatibility with existing second-generation technologies.

The rats treated with a single i.p. injection of diethylnitrosoamine (DEN) and percial hepatectomy were fed for 11 weeks with a high fat diet mixed with 10% lard, eicosapentaenoic-acid-rich oil (EPA-oil) or arachidonic-acid-rich oil (AA-oil) and the emergence of glutathione S-transferase placental form (GST-P) in the liver was evaluated. There were no significant differences in the serum aminotransferase activities. The molar ratio of n-6 and n-3 fatty acid in the liver phospholipids was significantly low in the EPA-oil group compared with the other groups. In the EPA-oil group, the area percent and the unit area of GST-P positive foci were significantly smaller than the other groups. In the AA-oil group, no significant differences were recognized in the quantitative values for GST-P positive foci compared with the control and lard groups. In conclusion, a hepatic neoplasmic lesion induced by DEN was suppressed with EPA-rich fish oil, and arachidonic-acid-rich oil showed no effect of suppression or acceleration.

Results are reported on the molecular-beam epitaxial (MBE) growth and electrical performance of HgCdTe midwave-infrared (MWIR) detector structures. These devices are designed for operation in the 140–160 K temperature range with cutoff wavelengths ranging from 3.4–3.8 µm at 140 K. Epitaxial structures, grown at 185°C on (211)B-oriented CdZnTe substrates, consisting of either conventional two-layer P-n configurations or three-layer P-n-N configurations, were designed to examine the impact of device performance on variation of the n-type base layer (absorber) thickness and the inclusion or omission of an underlying wide-bandgap buffer layer. Devices were grown with absorber thicknesses of 3 µm, 5 µm, and 7 µm to examine the tradeoff between the spectral response characteristic and the reverse-bias electrical performance. In addition, 5-µm-thick, wide-bandgap HgCdTe buffer layers, whose CdTe mole fraction was approximately 0.1 larger than the absorber layer, were introduced into several device structures to study the effect of isolating the device absorbing layer from the substrate/growth initiation interface. The MBE-grown epitaxial wafers were processed into passivated, mesa-type, discrete device structures and diode mini arrays, which were tested for temperature-dependent R0A product, quantum efficiency, spectral response, and the I-V characteristic at temperatures close to 140 K. External quantum efficiencies of 75–79% were obtained with lateral optical-collection lengths of 7 µm. Analysis of the temperature dependence of the diode R0A product indicates that the device impedance is limited by the diffusion current at temperatures above 140 K with typical R0A values of 2×106 Ω cm2 for a detector cutoff of 3.8 µm at 140 K. An alloy composition anomaly at the absorbing-layer/buffer-layer interface is believed to limit the observed R0A products to values approximately one order of magnitude below the theoretical limit projected for radiatively limited carrier lifetime. Device electrical performance was observed to be improved through incorporation of a wide-bandgap buffer layer and through reduction of the absorbing layer thickness. An optimum spectral response characteristic was observed for device structures with 5-µm-thick absorbing layers.

Excessive dopant or compositional mixing (interdiffusion) during the processing of HgCdTe photodiodes can lead to significant reductions in device performance. With the advent of multi-color and wider bandgap detectors, processes developed for single color LWIR and MWIR devices may not be transferable to the more complex structures. An important factor to account for in processing multicolor and wider gap HgCdTe is the effect of the Fermi level on point defect (PD) concentrations. In general, the density of PDs that have donor states in the band gap will be boosted in the presence of acceptors through the energy gained by the donor state electrons dropping into the vacant acceptor states. The density of PDs that have acceptor states in the band gap will be boosted in the presence of donors through a similar compensation mechanism. This Fermi-level effect is increasingly more important as the band gap is widened. Since almost all diffusion is mediated by either native and/or dopant point defects, and the intrinsic carrier concentration is relatively low at typical processing temperatures, significant broadening of composition and dopant profiles can occur in moderately and heavily doped HgCdTe. In this paper, we illustrate the Fermi-level effect on diffusion with two examples: compositional interdiffusion in multicolor detectors and diffusion of indium in MWIR and SWIR detectors.

Molecular-beam epitaxy (MBE) has been utilized to fabricate HgCdTe heterostructure separate absorption and multiplication avalanche photodiodes (SAM-APD) sensitive to infrared radiation in the 1.1-1.6 μm spectral range, as an alternative technology to existing III-V APD detectors. Device structures were grown on CdZnTe(211)B substrates using CdTe, Te, and Hg sources with in situ In and As doping. The composition of the HgCdTe alloy layers was adjusted to achieve both efficient absorption of IR radiation in the 1.1-1.6 μm spectral range and low excess-noise avalanche multiplication. The Hg 1-x Cd x Te alloy composition in the gain region of the device, = 0.73, was selected to achieve equality between the bandgap energy and spin-orbit splitting to resonantly enhance the impact ionization of holes in the split-off valence band. The appropriate value of this alloy composition was determined from analysis of the 300 K bandgap and spin-orbit splitting energies of a set of calibration layers, using a combination of IR transmission and spectroscopic ellipsometry measurements. MBE-grown APD epitaxial wafers were processed into passivated mesa-type discrete device structures and diode mini-arrays using conventional HgCdTe process technology. Device spectral response, dark current density, and avalanche gain measurements were performed on the processed wafers. Avalanche gains in the range of 30-40 at reverse bias of 85-90 V and array-median dark current density below 2 x 10 -4 A/cm 2 at 40 V reverse bias have been demonstrated.

Molecular beam epitaxy was employed for the growth of HgCdTe-based n-p+-n device structures on (211)B oriented CdZnTe substrates. The device structures were processed as mesa isolated diodes, and operated as back-to-back diodes for the simultaneous detection of two closely spaced sub-bands in the mid-wave infrared spectrum. The devices were characterized by R0A values in excess of 5 × 105 Ω cm2 at 78K, at f/2 fov and quantum efficiencies greater than 70% in each band. Infrared imagery from a focal plane array with 128 × 128 pixels was acquired simultaneously from each band at temperatures between 77 to 180K, with no observable degradation in the image quality with increase in temperature.

In situ doped HgCdTe two-color detectors with the n-p-n geometry were grown by molecular beam epitaxy, for the simultaneous detection of two closely spaced bands in the mid-wave infrared spectrum. The average near-surface etch pit densities in these layers were 5 x10 6 cm -2 , which is a factor of 10 higher than that observed for the lattice-matched growth of Hg 1-x Cd x Te (x =0.22) layer on Cd 0.96 Zn 0.04 Te substrates. The 0.04% lattice mismatch between the Hg 1-x Cd x Te (x = 0.35) epilayer and the Cd 0.9 Zn 0.04 Te substrate produces plastic deformation of the epilayer which results in an increased dislocation densities in the epilayer. The alloy composition across the device structure along the growth direction was determined by secondary ion mass spectrometric analysis, and deviated by less than 1% from the target. The device structures were processed as diodes with the mesa architecture and tested. The spectral response of the detectors at 77 K was characterized by sharp turn off at 3.7 and 4.4 μm. R 0 A values in excess of 1 x 10 6 Ω cm 2 and quantum efficiencies greater than 75% were measured for diodes in each band.

High-performance in situ doped two-color detectors with the n-p-n architecture for the sequential detection of mid: and long-wave infrared radiation were grown by molecular beam epitaxy. These detector structures were twin-free, and exhibited narrow rocking curves ( 45 arcsec) as determined by X-ray measurements. The near surface etch pit densities in these device structures were typically (2-3) x 10 6 cm -2 . The structures were processed as mesas and their electrical properties measured. The spectral response of the mid-wave and long-wave diodes in the integrated detector were characterized by sharp turn-on and turn-off in both bands. Average R o A values of 100 Ω cm 2 at 10.5 μm and 5.5 x 10 5 Ω cm 2 at 5.5 μm were measured at 77 K. These results are comparable to those of the best unispectral detectors and represents a significant milestone for MBE-grown HgCdTe two-color devices

The InAs/Ga1−xInxSb strained‐layer superlattice (SLS) holds promise as an alternative III–V semiconductor system for long wavelength infrared detectors. In this article, we present the first investigation, to the best of our knowledge, of heterojunction photodiodes using this new material. The devices were grown by molecular beam epitaxy on GaSb substrates, and are comprised of a 38 A InAs/16 A Ga0.64In0.36Sb SLS used in double heterojunctions with GaSb contact layers. The structures were designed to optimize the quantum efficiency while minimizing transport barriers at the heterointerfaces. The photodiodes are assessed through the correlation of their performance with the SLS material quality and the detector design. X‐ray diffraction, absorption, and Hall measurements are used to determine the SLS material properties. The electrical and optical properties of the photodiodes are determined using current–voltage and spectral responsivity measurements. At 78 K, these devices exhibit rectifying electrical behavior and photoresponse out to a wavelength of 10.6 μm corresponding to the SLS energy gap. The responsivity and resistance in these thin‐layered (0.75 μm), unpassivated photodiodes result in a detectivity of 1×1010 cm √Hz/W at 8.8 μm and 78 K. Based upon the performance of these devices, we conclude that high‐sensitivity operation of long‐wavelength photovoltaic detectors at temperatures well in excess of conventional III–V band gap‐engineered systems, and potentially in excess of HgCdTe, is feasible using this material system.

In this article, device modeling refers to numerical simulation of semiconductor device physics to predict electrical behavior. The silicon integrated circuit industry provides the example for the use of technology computer-aided design to simulate wafer fabrication processes, and the electrical performance of devices and circuits. This paper first reviews semiconductor device modeling in general, then as applied in work supporting the development and analysis of HgCdTe infrared detectors. Example applications of one- and two-dimensional device modeling are simulation of a bias-selectable, integrated two-color detector, and two-dimensional effects on the spectral response of a HgCdTe detector with composition grading.

HgCdTe MBE technology is becoming a mature growth technology for flexible manufacturing of short-wave, medium-wave, long-wave, and very long-wave infrared focal plane arrays. The main reason that this technology is getting more mature for device applications is the progress made in controlling the dopants (both n-type and p-type in-situ) and the success in lowering the defect density to less than 2 x 105/cm2 in the base layer. In this paper, we will discuss the unique approach that we have developed for growing As-doped HgCdTe alloys with cadmium arsenide compound. Material properties including composition, crystallinity, dopant activation, minority carrier lifetime, and morphology are also discussed. In addition, we have fabricated several infrared focal plane arrays using device quality double layers and the device results are approaching that of the state-of-the-art liquid phase epitaxy technology.

This paper is a discussion of the influence of heterojunction barriers on minority‐carrier hole transport in wide band gap p+ on narrow gap n HgxCd1‐xTe diodes that are illuminated from the n side. We have simulated detectors with 10.5 μm cut off wavelengths at 80 K by numerically solving the coupled transport and continuity equations for electrons and holes with Poisson’s equation. Parameters in the modeling include the composition of the p+ cap layer, the composition grading width, the doping of the base layer, temperature, and detector bias. The modeling predicts that the ratio of the quantum efficiency in a device with a barrier height of 2kT to that of a detector with no barrier is 0.95, while a 4.5kT barrier gives a value of 0.5. The model calculations have been qualitatively confirmed by experimental measurements of x=0.42/0.22 and 0.30/0.22 heterojunctions in which the doping in the low band gap n layer was varied to adjust the height of the heterojunction barrier.

HgCdTe APDs and APD arrays offer unique advantages for high-performance eyesafe LADAR sensors. These include: operation at room temperature, low-excess noise, high gain, high-quantum efficiency at eyesafe wavelengths, GHz bandwidth, and high-packing density. The utility of these benefits for systems are being demonstrated for both linear and area array sensors. Raytheon has fabricated 32 element linear APD arrays utilizing liquid phase epitaxy (LPE), and packaged and integrating these arrays with low-noise amplifiers. Typical better APDs configured as 50-micron square pixels and fabricated utilizing RIE, have demonstrated high fill factors, low crosstalk, excellent uniformity, low dark currents, and noise equivalent power (NEP) from 1-2 nW. Two units have been delivered to NVESD, assembled with range extraction electronics, and integrated into the CELRAP laser radar system. Tests on these sensors in July and October 2000 have demonstrated excellent functionality, detection of 1-cm wires, and range imaging. Work is presently underway under DARPA's 3-D imaging Sensor Program to extend this excellent performance to area arrays. High-density arrays have been fabricated using LPE and molecular beam epitaxy (MBE). HgCdTe APD arrays have been made in 5 X 5, 10 X 10 and larger formats. Initial data shows excellent typical better APD performance with unmultiplied dark current < 10 nA; and NEP < 2.0 nW at a gain of 10.

Since its initial synthesis and investigation more than 40 years ago, the HgCdTe alloy semiconductor system has evolved into one of the primary infrared detector materials for high-performance infrared focal-plane arrays (FPA) designed to operate in the 3-5 mm and 8-12 mm spectral ranges of importance for thermal imaging systems. Over the course of the past decade, significant advances have been made in the development of thin-film epitaxial growth techniques, such as molecular-beam epitaxy (MBE), which have enabled the synthesis of IR detector device structures with complex doping and composition profiles. The central role played by in situ sensors for monitoring and control of the MBE growth process are reviewed. The development of MBE HgCdTe growth technology is discussed in three particular device applications: avalanche photodiodes for 1.55 +m photodetection, megapixel FPAs on Si substrates, and multispectral IR detectors.

A number of developmental regulatory genes, including homeobox genes, are dynamically expressed in the mammalian cephalic ectomesenchyme during craniofacial morphogenesis. Owing to the vast amount of gene knock out experiments, functions of such genes are now being revealed in the mammalian skeletal patterning process. The murine goosecoid (Gsc) and Msx1 genes are expressed during craniofacial development and each mutant mouse displays intriguing facial abnormalities including those of middle ear ossicles, suggesting that both genes play roles in spatial programming of craniofacial regions. In order to examine whether these genes could function in concert to direct particular craniofacial morphogenesis, double knock out mice were analyzed. The phenotype of the double mutant mice was restricted to the first arch derivatives and was apparently additive of the single gene mutant mice, implying region specific genetic interactions of these homeobox genes expressed in overlapping regions of middle ear forming ectomesenchyme. Our results also suggested that the patterning of distal portions of the malleus depends on the tympanic membrane, for which normal expressions of both the genes are prerequisite.

Separate absorption and multiplication avalanche photodiode (SAM-APD) device structures, operating in the 1.1 - 1.6 micrometer spectral range, have been fabricated in the HgCdTe material system by molecular-beam epitaxy. These HgCdTe device structures, which offer an alternative technology to existing III-V APD detectors, were grown on CdZnTe(211)B substrates using CdTe, Te, and Hg sources with in situ In and As doping. The alloy composition of the HgCdTe layers was adjusted to achieve both efficient absorption of IR radiation in the 1.1 - 1.6 micrometer spectral range and low excess-noise avalanche multiplication. To achieve resonant enhancement of hole impact ionization from the split-off valence band, the Hg1-xCdxTe alloy composition in the gain region of the device, x equals 0.73, was chosen to achieve equality between the bandgap energy and spin-orbit splitting. The appropriate value of this alloy composition was determined from analysis of the 300 K bandgap and spin-orbit splitting energies of a set of calibration layers, using a combination of IR transmission and spectroscopic ellipsometry measurements. MBE-grown APD epitaxial wafers were processed into passivated mesa-type discrete device structures and diode mini-arrays using conventional HgCdTe process technology. Device spectral response, dark current density, and avalanche gain measurements were performed on discrete diodes and diode mini- arrays on the processed wafers. Avalanche gains in the range of 30 - 40 at reverse bias of 85 - 90 V and array-median dark current density below 2 X 10-4 A/cm2 at 40 V reverse bias have been demonstrated.

In this paper results are presented from a study of interdiffusion in HgTe/CdTe heterostructures. The samples were grown by MBE at HRL Laboratories and had Cd x values ranging from 0.2 to 0.35. The samples were annealed at temperatures ranging from 250 deg C to 425 deg C in both Hg vapor and vacuum ambients. The samples annealed under vacuum were coated with a layer of CdTe prior to annealing. The data were simulated using Darken's equation, and results show strong agreement between the simulated and experimental profiles. Significantly more diffusion was observed for anneals under Hg-rich ambients than under vacuum. For Hg-rich anneals, the activation energy was 1.50 eV at temperatures less than 350 deg C and 1.33 eV at higher temperatures. This is the first time that two activation energies for the interdiffusion coefficient have been reported. The mechanisms responsible for this behavior are discussed.

To explore gene therapy as a new treatment modality for hepatocellular carcinoma, a pre-clinical animal model was established by intrahepatic implantation of a mouse hepatocellular carcinoma cell line (MH134) in syngeneic recipients. The resulting hepatic tumors were treated with a recombinant adenoviral vector expressing the murine interleukin-2 (IL-2) gene, and long-term remission was achieved in 50% of the animals. The remaining animals died of malignant ascites, which also occurs in some human patients. Those animals were treated with a second dose of the recombinant adenoviral vector by direct inoculation into the peritoneal cavity, and long-term remission of the disseminated disease was achieved in 55% of the animals. Thus, a combined cure rate of greater than 75% for primary- and disseminated hepatocellular carcinoma was achieved by successive adenovirus-mediated IL-2 gene treatments. Histopathological and immunocytochemical analyses showed massive infiltration of the tumor by macrophages and T lymphocytes in IL-2 vector treated animals. The surviving animals developed systemic antitumoral cellular immunity that protected them against challenges of parental hepatoma cells implanted at distant sites. The results suggest that IL-2 gene therapy may be a strategy applicable for the treatment of both primary and metastatic hepatocellular carcinomas in man.

Metastases of breast cancer are a major cause of treatment failure. To evaluate the therapeutic efficacy of suicide gene therapy in metastatic breast cancer, we used the herpes simplex virus thymidine kinase (HSV-tk) gene followed by ganciclovir (GCV) administration to treat breast cancer, generated by an adenocarcinoma cell line MOD in syngeneic mice. The bystander effect of HSV-tk + GCV on tumor cell killing was illustrated by demonstrating complete regression of subcutaneous tumors consisting of 90% parental tumor cells and 10% HSV-tk transformed tumor cells. To establish a model of breast cancer metastases in the liver, tumors were generated by intra-hepatic implantation of MOD cells in syngeneic animals. Two weeks after tumor cell implantation, replication defective adenoviral vectors expressing HSV-tk (ADV.tk), or beta-galactosidease (ADV. beta-Gal) were injected intratumorally, followed by buffer or GCV administration. Treatment with ADV.tk + GCV resulted in significant regression of tumor (P.001), as assessed by computerized morphometric analysis of residual tumor. This was reflected as a significant prolongation of survival in treated animals (P.001). These results demonstrate that ADV-mediated suicide gene therapy in vivo can be incorporated in a comprehensive treatment strategy for liver metastases of breast cancer.

The effectiveness of combination therapy using a suicide gene and cytokine genes for the treatment of metastatic colon carcinoma in the mouse liver was investigated. Pre-established hepatic tumors treated with a recombinant adenoviral vector containing the herpes simplex virus thymidine kinase gene(tk) exhibited substantial regression, although all treated animals suffered from subsequent relapses. Although cotreatment with a mouse interleukin 2 (mIL-2)-containing adenoviral vector induced an effective antitumor immune response, the immunity waned with time, and the treated animals eventually succumbed to hepatic tumor relapse or distant metastases. In this study, mouse granulocyte macrophage colony-stimulating factor (mGM-CSF) gene was tested for its ability to further enhance and prolong the antitumoral cellular immunity. A fraction of the animals treated with tk + mIL-2 + mGM-CSF developed long-term antitumor immunity and survived for more than 4 months without recurrence. This long-term antitumor immunity could be enhanced further by subsequent "vaccination" with mIL-2-expressing parental tumor cells. The results indicate that local expression of GM-CSF in the hepatic tumors and prolonged mIL-2 expression are necessary to generate persistent antitumor immunity that is essential for the prevention of tumor recurrence and long-term animal survival.

Molecular beam epitaxy (MBE) offers benefits such as the capability for growth of compositionally-tailored heterostructures and in-situ doping of HgCdTe alloys. These capabilities were applied to the growth of long wave infrared unispectral focal plane arrays (FPA) with 480×4 elements. The detectivity (D*) map of the FPA demonstrated performance that was higher than the specification value, with no defective channels. Two-color detectors with the n-p-n architecture, for the simultaneous detection of two closely spaced bands in the midwave infrared spectrum were also grown by MBE. These devices exhibited sharp turn-off and turn-on in both bands. The quantum efficiency was greater than 70% and average R°A values exceeded 1×106 Ω-cm2 in both bands. These result demonstrate that high performance HgCdTe devices can be grown by MBE.

Integrated two-color detector arrays offer significant system advantages (over separate arrays for each color) where two-color information is required. Using a single array with co-located spectral band sensitivities guarantees perfect pixel registration between the two different spectral band images. These two-color IR detectors can be made in HgCdTe using a pair of back-to-back-diodes incorporated in a triple-layer heterojunction (TLHJ). Use of HgCdTe allows any combination of bands between SWIR and LWIR. TLHJs can be operated in either a sequential or simultaneous mode by leaving the layer common to the two diodes floating or by contacting it. The effect of the choice of spectral bands on the meaning of sequential and simultaneous operation is discussed. State-of-the-art trend line performance for each spectral band of a TLHJ has been demonstrated using an all-LPE HgCdTe technology at SBRC. Mean MWIR RrA of 2 X 107 (Omega) -cm2 and LWIR of 1.6 X 103 (Omega) -cm2 have been shown. Quantum efficiencies are typical of trend line PV HgCdTe. Very high quality imaging has been demonstrated using 64 X 64 sensor chip assemblies in a sequential mode incorporating the above TLHJs. Simultaneous detectors have been made in miniarrays and test structures of various size unit cells. 128 X 128 simultaneous arrays are under study. Imaging and test results (performance and uniformity) for each band are comparable to state-of-the-art single-color HgCdTe arrays.

Deciding which orthosis would be best suited for a given patient is a complex process involving many different factors. The fancy names used by laboratories to describe their products only add to the confusion when the practitioner is attempting to determine the best device. The ability to successfully manage biomechanical abnormalities may be enhanced by understanding the properties of different orthotic materials and the associated patient factors involved. The podiatric practitioner also should be aware that the grade and quality of materials are not the same from different manufacturers, and that the way laboratories handle the materials also affects the final properties of the orthosis. For this reason, it is beneficial to sample orthoses from various laboratories, and to feel comfortable in asking for technical assistance when ordering.

We report a neonatal case of hepatic cytomegalovirus (CMV) infection associated with paucity of interlobular bile ducts. The premature infant developed severe jaundice, and died of disseminated CMV infection. The diagnosis of CMV infection was based on detection of pathognomonic inclusions in the liver and on a high titer of CMV antibody in the serum. The hepatic histologic findings in this infant included severe cholestasis, complete absence of interlobular bile ducts in the majority of the portal tracts, and CMV inclusions in the duct epithelium. Interestingly, the CMV inclusions were localized in the bile duct, but not in the parenchyma. We postulate that the paucity of interlobular bile ducts may have been a sequela of CMV infection of the liver arising from destruction of the bile ducts, leading to severe cholestasis.

Molecular beam epitaxy (MBE) has been utilized to fabricate high performance HgCdTe infrared detectors with sensitivity to midwave infrared radiation in adjacent spectral bands for two-color thermal imaging applications. Growth of a multilayer HgCdTe device structure by MBE enables the use of an n-p-n device architecture that facilitates pixel-level registration of images in two separate spectral bands. Device structures were grown on CdZnTe(211)(B) substrates using CdTe, Te, and Hg sources with in situ In and As doping. The composition of the HgCdTe alloy layers was adjusted to achieve detection of infrared radiation in adjacent spectral bands in the 3.5–4.5 μm wavelength range. As-grown device structures were characterized with x-ray diffraction, wet chemical defect etching, and secondary ion mass spectrometry. Mesa type devices were patterned using reactive ion etching and ohmic contacts were made to the two n-type layers for operation of the detectors in a sequential detection mode. The spectral respo...

Volatile concentrates were prepared from whole soybeans, roasted at 200°C for 10, 20 and 30 min, by steam distillation under reduced pressure followed by ether extraction, and analysed by gas chromatography and gas chromatography-mass spectrometry, in comparison with the volatile concentrate from raw soybean flour. Major flavour components of raw soybean, such as n -hexanol, 1-octen-3-ol and n -hexanal, decreased during the course of roasting, but the rate of this decrease was not rapid, especially between 10 and 20 minutes' roasting. During the roasting period, alkylated pyrazines, oxygenated furans, oxygenated pyrroles and phenols were formed or increased markedly. On the other hand, sensory evaluation showed that a flavour change to ‘desirable’ from ‘beany’ or ‘objectionable’ occurred between 10 and 20 minutes' roasting. These results suggest that roast flavour masks the ‘beany’ flavour in soybean.

A simple and easily installed modification is described which upon application of external pulses causes the undelayed opening of the gates in the signal processing modules of a Princeton Applied Research Model 162 boxcar integrator. This allows the timing for the aperture delays to be done externally with digital circuitry, thus simplifying the setting of time parameters in deep level transient spectroscopy (DLTS) measurements, as well as giving increased time accuracy, stability, and easier interfacing to a computer. A second circuit is also described which, when used with a modified 162, permits double correlation DLTS to be performed with one, instead of two, instruments.

Deep electron levels in n‐type liquid phase epitaxial ZnSe have been studied using thermally stimulated capacitance, photocapacitance, and deep level transient spectroscopy (DLTS). Electron traps have been observed with activation energies of 0.17, ∼0.3, 0.64, and 1.4 eV below the conduction band. The electron emission‐rate dependence on temperature as measured by DLTS has been found to vary among samples for the 0.3 eV level.

The current interest in HgTe/CdTe superlattices (SL’s) stems in part from their potential usefulness in advanced IR applications. Of particular interest is the photon energy dependence of the optical absorption coefficient α(E) of these superlattices. Structure in α(E) of superlattices is expected because of the relatively narrow energy subbands (compared with bulk semiconductors) resulting from the large SL period (∼100 A). Determination of this structure will help to reveal the electronic subband structure of the superlattice. We report here the experimental and theoretical extraction of α(E) at 300 K for six HgTe/CdTe superlattices. The experimentally determined αexp(E) were obtained from transmission/reflection data in conjunction with a computer model. The theoretically calculated αcalc(E) was computed using a two‐band tight‐binding model for the superlattice energy bands in the growth direction and a nonparabolic approximation in the superlattice plane. Subband related structure is observed for all ...

The WKB method has been used to extract the asymptotic behavior of the solution to the charge transfer equation in a CCD with thermal diffusion and fringing-field drift. This enables an excellent approximation to be calculated for the decay time constant and charge distribution while using only a small number of parameters in a variational function.

Shallow acceptors have been incorporated in ZnSe by liquid‐phase epitaxy using Bi as a solvent. Epilayers with Li, Na, N, and P as dopants were proven to be p type by establishing the position of the Fermi level by photocapacitance and photoconductivity measurements, and by measuring the potential drop at biased Schottky barriers.

It is pointed out that next-generation sensors for earth observation will utilize Multispectral Linear Array (MLA) technology wherein linear detector arrays will scan the earth in pushbroom fashion. MLA instruments will permit a dramatic increase in detector dwell time, which can be utilized to improve spatial, spectral, and radiometric resolution. In connection with the considered applications for MLA sensors, the employed detector arrays should cover the visible, near-infrared, and shortwave infrared (SWIR) spectral bands. The present paper is mainly concerned with the development of mercury-cadmium-telluride focal-plane arrays for the SWIR spectral regime (1-2.5 microns). Attention is given to the requirements, design details regarding the detector array, the employed multiplexer technique, the hybrid concept, packaging, and the program status.

Publisher Summary This chapter focuses on the properties of deep states in wide band-gap III–V semiconductors. Deep states are important in semiconductors in general and very often determine the recombination properties. Wide band-gap III-V compounds are now commonly used for many important optoelectronic devices and are suggested for additional interesting applications. In discussing deep levels in wide band-gap semiconductors, the first requirement is to define “deep” and “wide.” The latter can be done relatively easily, although arbitrarily. “Deep” is defined in terms of the recombination properties because of the profound influence of such recombination on material behavior. Properties specifically affected can include the minority-carrier lifetime and the luminescence efficiency. If deep levels dominate the recombination, these properties will be degraded from the value obtained from the dopants, which are deliberately added impurities, used to provide either desired electrical and/or luminescent properties. A convenient way of quantifying the importance of “deep” levels to recombination is via the “occupancy” factor of a level. Various methods available for the characterization and compilation of levels reported in gallium arsenide (GaAs) and gallium phosphide (GaP) are discussed in the chapter.