Periodic open and closed resonators as a biosensor using two computational methods.

The volatile particles and molecules in our dry exhaled breath can reveal enormous information about the health of any person, such as the person's respiratory and metabolic functioning. Beyond the carbon dioxide level is an indicator of life, it provides important health-related data like people's metabolic rate. This study considers periodic open and closed resonators for measuring carbon dioxide concentration in dry exhaled breath. Transfer matrix and green methods are used to simulate the interaction between acoustic waves and the proposed sensor. The band gaps using the green method coincide with the transmittance spectra by the transfer matrix. The suggested sensor recorded a sensitivity of 5.3 H z . m - 1 . s , a figure of merit of 10,254 m - 1 . s , a detection limit of 5 × 10 - 6 m . s - 1 , and a quality factor of 3 × 10 6 . Furthermore, the efficiency shows that the proposed design is appropriate as a diagnostic sensor for different diseases such as chronic obstructive pulmonary. Besides, cylindrical-adapted sensors are urgently needed in medicine, industry, and biology because they can simultaneously be used for fluid transport and detection.

Theoretical optimisation of a novel gas sensor using periodically closed resonators.

This study investigates using the phononic crystal with periodically closed resonators as a greenhouse gas sensor. The transfer matrix and green methods are used to investigate the dispersion relation theoretically and numerically. A linear acoustic design is proposed, and the waveguides are filled with gas samples. At the center of the structure, a defect resonator is used to excite an acoustic resonant peak inside the phononic bandgap. The localized acoustic peak is shifted to higher frequencies by increasing the acoustic speed and decreasing the density of gas samples. The sensitivity, transmittance of the resonant peak, bandwidth, and figure of merit are calculated at different geometrical conditions to select the optimum dimensions. The proposed closed resonator gas sensor records a sensitivity of 4.1 Hz m-1 s, a figure of merit of 332 m-1 s, a quality factor of 113,962, and a detection limit of 0.0003 m s-1. As a result of its high performance and simplicity, the proposed design can significantly contribute to gas sensors and bio-sensing applications.

Design of phononic crystal using open resonators as harmful gases sensor.

This paper investigates the ability to use a finite one-dimensional phononic crystal composed of branched open resonators with a horizontal defect to detect the concentration of harmful gases such as CO2. This research investigates the impact of periodic open resonators, defect duct at the center of the structure, and geometrical parameters such as cross-sections and length of the primary waveguide and resonators on the model's performance. As far as we know, this research is unique in the sensing field. Furthermore, these simulations show that the investigated finite one-dimensional phononic crystal composed of branched open resonators with a horizontal defect is a promising sensor.

Simulation study of gas sensor using periodic phononic crystal tubes to detect hazardous greenhouse gases.

Here, we investigate a gas sensor model based on phononic crystals of alternating tubes using the transfer matrix method to detect hazardous greenhouse gases. The effect of the thicknesses and cross-sections of all tubes on the performance of the proposed sensor is studied. The results show that longitudinal acoustic speed is a pivotal parameter rather than the mass density variations of the gas samples on the position of the resonant peaks due to its significant impact on the propagation of the acoustic wave. The suggested sensor can be considered very simple and low-cost because it does not need a complicated process to deposit multilayers of different mechanical properties' materials.

Refractive index sensor with magnified resonant signal.

Herein, we theoretically suggest one-dimensional photonic crystal composed of polymer doped with quantum dots and porous silicon. The present simulated design is proposed as a refractive index biosensor structure based on parity-time symmetry. Under the parity-time conditions, the transmittance of the resonant peaks is magnified to be 57,843% for refractive index 1.350, 2725% for 1.390, 2117% for 1.392, 1502% for 1.395, 1011% for 1.399, and 847% for 1.401. By magnification, we can distinguish between different refractive indices. The present design can record an efficiency twice the published designs as clear in the comparison table. Results clear that the sensitivities are 635 nm/RIU and 1,000,000%/RIU. So, it can be used for a broader range of detection purposes.

Novel smart window using photonic crystal for energy saving.

Smart windows are emerging as an effective way of minimizing energy consumption in buildings. They attracted the major relevance for minimizing energy consumption in buildings. More research studies are needed to design smart windows with operating wide range and don't require additional energy to operate. We suggest a novel smart window structure using photonic crystal to regulate the solar radiation intensity by preventing it from penetrating the buildings in summer. For the first time, the suggested smart window photonic crystal at room temperature is proposed. The suggested smart window can block about 400 nm of near-infrared. This smart window model doesn't require additional heat or electric input to operate.

The impact of magnetized cold plasma and its various properties in sensing applications.

These analyses present a novel magnetized cold plasma-based 1D photonic crystal structure for detecting the refractive index of various bio-analytes. The proposed structure is designed with two photonic crystals composed of an alternating layer of right-hand polarization and left-hand polarization of the magnetized cold plasma material with a central defect layer. Transmittance characteristics of the structure are studied by employing the well-known transfer matrix method. Various geometrical parameters such as electron density, external magnetic field, thickness of odd and even layers of the multilayers, thickness of the sample layer, and incident angle are judiciously optimized to attain the best sensitivity, figure of merit, quality factor, signal-to-noise ratio, detection range and limit of detection. Finally, a maximum sensitivity of 25 GHz/RIU is accomplished with the optimized value of structure parameters, which can be considered as a noteworthy sensing performance.

Plasma cell sensor using photonic crystal cavity.

The performance of one-dimensional photonic crystal for plasma cell application is studied theoretically. The geometry of the structure can detect the change in the refractive index of the plasma cells in a sample that infiltrated through the defect layer. We have obtained a variation on the resonant peak positions using the analyte defect layer with different refractive indices. The defect peak of the optimized structure is red-shifted from 2195 to 2322 nm when the refractive index of the defect layer changes from 1.3246 to 1.3634. This indicates a high sensitivity of the device (S = 3300 nm/RIU) as well as a high Q-factor (Q = 103). The proposed sensor has a great potential for biosensing applications and the detection of convalescent plasma.

Gyroidal graphene/porous silicon array for exciting optical Tamm state as optical sensor.

In this study, the optical Tamm state is excited for the first time using gyroidal graphene/porous silicon one-dimensional photonic crystal terminated by a gyroidal graphene layer. The gyroidal graphene and porous silicon are used to enhance the figure of merit and sensitivity of the based Tamm resonance photonic crystal sensor. By tuning different parameters like the angle of incidence, the thickness of the sample layer, and the thickness of the gyroidal graphene layer, we have reached the optimized sensor. The observation of resonant dips in the reflectance spectra is strong evidence that Tamm plasmon-polaritons exist with higher sensitivity (188.8 THz/RIU) and figure of merit (355,384 RIU-1) than previously reported structures. The proposed sensor recorded sensitivity and FoM higher 38% and 747% respectively than a similar structure composed of graphene sheets and porous silicon.

Modeling of a biosensor using Tamm resonance excited by graphene.

In this paper, nanoscale pores in silicon layers are exploited to model and optimize a one-dimensional hybrid graphene-porous silicon photonic crystal biosensor. The physical nature of the proposed sensor is based on Tamm resonance. The transfer matrix method is applied to detect the change of the index of refraction in an aqueous solution. The proposed model is (PSi1/PSi2)N/G/Substrate, in which PSi1 and PSi2 are porous silicon layers with different porosities, N is the number of periods, and G is the number of graphene layers. The numerical simulations show that the proposed sensor has good performance. The variation of the number of periods, number of graphene layers, porosities, thicknesses of silicon layers, incident angles, and the sample layer thickness affect the performance of the sensor. By varying these parameters, the sensitivity and figure of merit of the sensor can be controlled. The study shows that the sensitivity and figure of merit of the proposed sensor reach 4.75 THz/RIU and 475RIU-1, respectively. The proposed sensor has a good capability in biological detection within terahertz. It is the first time, to our knowledge, that graphene has been used to excite the Tamm resonance using the photonic crystal of porous silicon and using it in biosensing applications.

Refractive index gas sensor based on the Tamm state in a one-dimensional photonic crystal: Theoretical optimisation.

Gas sensors are important in many fields such as environmental monitoring, agricultural production, public safety, and medical diagnostics. Herein, Tamm plasmon resonance in a photonic bandgap is used to develop an optical gas sensor with high performance. The structure of the proposed sensor comprises a gas cavity sandwiched between a one-dimensional porous silicon photonic crystal and an Ag layer deposited on a prism. The optimised structure of the proposed sensor achieves ultra-high sensitivity (S = 1.9×105 nm/RIU) and a low detection limit (DL = 1.4×10-7 RIU) compared to the existing gas sensor. The brilliant sensing performance and simple design of the proposed structure make our device highly suitable for use as a sensor in a variety of biomedical and industrial applications.

Aluminum-induced molecular neurodegeneration: The protective role of genistein and chickpea extract.

Neurotoxicity of Al is well established and linked to oxidative damage and neurodegeneration. This study investigated the protective role of genistein (Gen) and chickpea extract (CPE) against AlCl3-induced neurodegeneration. HPLC analysis revealed that biochanin A-7-O-ß-D-glucoside and biochanin A are the major components of the CPE. Gene expression of TNF-α, APP, BACE1, PSEN-2 and ER-ß were assessed in brain extract using RT-PCR. Also, NF-кB subunit P65 and COX-2 expression were evaluated by western blotting. The cholinergic function, histological examination and oxidative status were also estimated. The AlCl3 significantly up regulated the expression of the NF-кB subunit P65, COX-2, TNF- α, BACE1and APP while it significantly down regulated PSEN-2 and ER-ß expression. The activity of acetyl cholinesterase (AChE) and the oxidative stress parameters as well as the histological examination confirmed the deleterious effect of AlCl3. The administration of either CPE or Gen attenuated the expression of inflammatory cytokines, inhibited the amyloidogenesis and restored both the AChE activity and ER-ß expression. Gen and CPE also inhibited the oxidative stress and ameliorated the histological alterations. Accordingly, the present study provides an insight on the molecular role of Gen and CPE as protective agents against neuronal injury.

Characteristics of sepsis-induced cardiac dysfunction using speckle-tracking echocardiography: a feasibility study.

Septic cardiomyopathy is commonly encountered in patients with severe sepsis and septic shock. This study explores whether novel global and segmental echocardiographic markers of myocardial deformation, using two-dimensional speckle tracking, are associated with adverse sepsis outcomes. We conducted a retrospective observational feasibility study, at a tertiary care centre, of patients admitted to the ICU with a diagnosis of sepsis who underwent an echocardiogram within the first week of sepsis diagnosis. Data were collected on chamber dimensions, systolic and diastolic function, demographics, haemodynamics, and laboratory parameters. Global and segmental left ventricular longitudinal strain (LVLS) and tissue mitral annular displacement (TMAD) were assessed on 12 left ventricular segments and six mitral annulus segments in apical views, respectively. We explored associations of abnormal LVLS and TMAD with duration of mechanical ventilation, hospital length of stay, and mortality. Fifty-four patients were included. Global LVLS was not associated with any of the primary study endpoints. However, reduced systolic LVLS of the basal anterior segment was associated with in-hospital mortality. There was a suggestion that patients with a reduced global TMAD were associated with an increased risk of mortality and a short length of hospital stay but these associations were not statistically significant. Reduced global LVLS was associated with lower ejection fraction. Reduced global TMAD was associated with reduced global and segmental LVLS, reduced left ventricular ejection fraction, and increased left ventricular end-systolic and end-diastolic volumes. Speckle-tracking echocardiography can be performed feasibly in patients in sepsis. Global and segmental left ventricular deformation indices are associated with ejection fraction. Further studies need to evaluate the ability of these new indices to predict sepsis outcomes.

Patient-level interventions to prevent the acquisition of resistant gram-negative bacteria in critically ill patients: a systematic review.

The rising incidence of multidrug-resistant Gram-negative bacterial (MDR-GNB) infections acquired in intensive care units has prompted a variety of patient-level infection control efforts. However, it is not known whether these measures are effective in reducing colonisation and infection. The purpose of this systematic review was to assess the efficacy of patient-level interventions for the prevention of colonisation with MDR-GNB and whether these interventions are associated with a reduction in the rate of infection due to MDR-GNB in the intensive care unit. Searches were conducted on PubMed, Cochrane, EMBASE and World of Science databases to identify comparative interventional studies on patient-level interventions implemented in the intensive care unit. Literature published in English, Spanish or French from January 1, 2000, until April 30, 2013, was searched. A total of 631 reports were found and we included and analysed 13 comparative studies that reported outcomes for an intervention compared with a control group. There were ten randomised and three observational interventional trials evaluating seven interventions. Overall, there was a reduction in colonisation (odds ratio [OR] 0.75; 95% confidence interval [CI] 0.66 to 0.85) and infection (OR 0.66; 95% CI 0.59 to 0.75) with MDR-GNB. This trend persisted after restricting pooled analysis to randomised controlled trials (pooled OR 0.66; 95% CI 0.57 to 0.76 and pooled OR 0.62; 95% CI 0.54 to 0.72, respectively). We identified a significant reduction in MDR-GNB colonisation and infection through the use of patient-level interventions. This effect was mostly accounted for by selective digestive decontamination. However, given the limitations of the analysed trials, adequately powered controlled studies are needed to further explore the effects of patient-level interventions on colonisation and infection with MDR-GNB.

The mechanism of protein release from triglyceride microspheres.

The purpose of this study was to reveal factors that have an impact on the protein release kinetics from triglyceride microspheres prepared by spray congealing. We investigated the effect of protein particle size, morphology and distribution on protein release from microspheres by confocal laser scanning microscopy (CLSM)(.) The microspheres were loaded with three types of model particles made of FITC-labeled bovine serum albumin: freeze dried protein, spherical particles obtained by precipitation in the presence of PEG and micronized material. Investigation by light microscopy and laser light diffraction revealed that the freeze dried material consisted mainly of app. 29 µm elongated shaped particles. The precipitated BSA consisted mainly of 9.0 µm diameter spherically shaped particles while the micronized protein prepared by jet milling consisted of 4.9 µm sized rounded particles of high uniformity. Microspheres were embedded into a cold-curing resin and cut with a microtome. Subsequent investigation by CLSM revealed major differences of distribution of the polydisperse protein particles inside the microsphere sections depending on the type of BSA that was used. Particles of micronized and precipitated protein were distributed almost throughout the microsphere cross section. The protein distribution had a marked impact on the release kinetics in phosphate buffer. Large protein particles led to a considerably faster release than small ones. By staining the release medium we demonstrated that in all three cases there was a strong correlation between protein release and buffer intrusion.

K-ras mutations and cell kinetics in Helicobacter pylori associated gastric intestinal metaplasia: a comparison before and after eradication in patients with chronic gastritis and gastric cancer.

BACKGROUND: Helicobacter pylori related gastric intestinal metaplasia (IM) is considered to be a precancerous lesion. AIMS: To identify the effects of H pylori eradication on K-ras mutations, cell kinetics in IM and histological changes in patients with and without gastric cancers in a one-year prospective study. METHODS: Patients included group A (n = 39), chronic gastritis, and group B (n = 53), intestinal-type early gastric cancer patients who had all undergone endoscopic mucosal resection (n = 25) or surgical resection (n = 28). K-ras codon 12 mutations in IM were examined, followed by DNA sequencing analysis. Proliferating and apoptotic cells were detected with anti-Ki-67 antibody and using the TUNEL method, respectively. RESULTS: The incidence of K-ras mutations in the cancer was only 3.8%. The mutant K-ras in IM was observed more frequently in group A (46.2%) than in group B patients (1.9%) (p<0.005). After eradication, the K-ras mutations significantly declined to 12.8% in group A (p<0.005). The mutation pattern of K-ras codon 12 before eradication was that GGT was mainly changed to AGT (50%) in group A. AGT transformation was not affected by treatment. Apoptosis in IM showed an increase after H pylori eradication in both groups (p<0.05 in group A) although no histological improvement in IM was observed. The monocyte score was significantly higher in group A than in group B (p<0.05); the score improved significantly after eradication. CONCLUSIONS: K-ras mutations in IM do not always play a role in gastric carcinogenesis but cell kinetics, especially apoptosis, in IM may contribute to it. There are early events in K-ras mutations which are influenced by H pylori infection; some mutations may also be selected by eradication. These unstable K-ras mutations in IM may be related to lymphocyte infiltration caused by H pylori infection.

Polyphasic taxonomy of symbiotic rhizobia from wild leguminous plants growing in Egypt.

About 20 strains of rhizobia from wild legumes were characterized based on numerical analysis of phenotypic characteristics, nodulating ability, fatty acid methyl esters (FAME) and SDS-PAGE profiles of whole cell proteins. FAME analysis revealed that palmitic (16:0), stearic (18:0) and arachidonic (20:0) were detected in most of wild-legume rhizobia, the latter being uncommon in fatty acid profiles of Rhizobium and Sinorhizobium. Numerical analysis of FAME classified strains of wild-legume rhizobia into 9 clusters and one heterogeneous group. There was both agreement and disagreement with the clustering data based on phenotypic analysis and FAME analysis. Four strains were grouped together in the same cluster based on both methods. However, 4 another strains, which were placed in one cluster of phenotypic analysis, were distributed in several clusters after FAME analysis. SDS-PAGE of whole-cell proteins revealed that the rhizobial strains exhibited protein profiles with peptide bands ranging from 5-19 band per profile and showed molar mass of 110-183 kDa. As in the case of FAME analysis, numerical analysis of protein bands was compared with clustering of phenotypic analysis. Agreement of the two methods was obvious when clustering some strains but conflicted in the classification of some other strains. However, integration of the three methods could be the basis of a polyphasic taxonomy. The twenty strains of wild-legume rhizobia were finally classified as follows: 12 strains related to Rhizobium leguminosarum, 5 strains related to Sinorhizobium meliloti and 3 strains to Rhizobium spp. Rhizobia nodulating wild herb legumes are among indigenous strains nodulating crop legumes in cultivated as well as noncultivated lands.

Isolation and characterization of distinct bioactive forms of LH from male buffalo pituitaries: differences localized to their alpha subunits.

The isolation of highly purified forms of pituitary LH from Egyptian male (Nile) buffaloes is described. The total LH content (receptor binding activity) which was approximately 30 to 50 fold higher than FSH in the pituitary could be divided into three pools based upon fractionation patterns on a cation exchanger. The acidic fraction which also contained FSH was not purified to homogeneity. A basic fraction (bu-LH-2; 300 mg/kg anterior pituitary) and a very basic fraction (bu-LH-3; 80 mg/kg) were both highly purified and free of FSH activity as tested by specific FSH receptor and immunoassays. The basic buffalo LH fraction, bu-LH-2, was as active as highly purified ovine LH (oLH). The most basic form of buffalo LH, bu-LH-3, was, however, about twice as active as highly purified oLH in the in vitro bioassay using mouse Leydig tumour (MA-10) cells. In a receptor binding assay employing 125I-labelled buffalo LH (bu-LH-3) and porcine testicular membranes, the affinity of bu-LH-3 was about five times higher than purified oLH. The M(r) of both forms of purified buffalo LH and subunits was similar to that of oLH. Amino acid composition of buffalo LH was also very similar to oLH except for small differences. Fractionation by fast protein liquid chromatography on Mono-Q columns revealed further evidence of microheterogeneity in each of the pools of buffalo LH with bu-LH-3 exhibiting a predominant single component. By reverse-phase high-pressure liquid chromatography analysis we have localized differences in the two purified isoforms of male buffalo LH to the alpha subunit. It is suggested that differences in biological potencies could be due to variations in terminal glycosylation and/or differences in branching of this subunit which is known to be important for signal transduction.

HLA-A, -B and -C specificities in insulin dependent diabetes mellitus in the Egyptian population.

The diversity of HLA antigens frequencies associated with Insulin Dependent Diabetes Mellitus (IDDM) reported in different populations raised the importance of determining HLA-A, -B and -C specificities in patients with IDDM in the Egyptian population. The study has been carried out on thirty patients with IDDM and thirty healthy control subjects matched for age and sex as patients included in the study. The results of the present work showed that patients with IDDM showed a significant increase in frequency of HLA-A2, HLA-B8 and HLA-B15. These findings are in accordance with the genetic heterogeneity of IDDM which is in turn in harmony with the modern concept on the complex aetiology of the disease. On the other hand, HLA-A3, HLA-B5 and HLA-B7 have been found significantly decreased in patients with IDDM, thus suggesting that these alleles may confer a protective effect from acquiring the disease. When HLA specificities have been studied in relation to the age of onset of the disease, HLA-A29 have been found in higher frequency in the age group after 15 years, while HLA-B15 in that before 15 years. This variability may be related to variation in the viral agents responsible for the infectious mechanism.

HLA-A, -B and -C specificities in a sample of the Nile Delta population, Egypt.

HLA-A, -B and -C specificities were determined in 100 Egyptians living and originating from the region of the Nile Delta. The pattern of antigen frequencies were similar to those of Berber populations living in North Africa with some exceptions compatible with the Semitic contribution to the Egyptian population.