A systematic study on MOS type radiation sensors

Radiation sensors based on metal oxide semiconductor (MOS) structure are useful because of their superior sensitivity as well as excellent compatibility with the existing microelectronic technology. In this paper, a systematic study of MOS capacitors built on p- and n-type Si substrates with different SiO₂ thicknesses (10 nm, 50 nm, 100 nm and 240 nm) is presented. MOS device response to gamma radiation up to 256 Gray have been studied from the sensor application point of view. Variation of the radiation induced device response with oxide thickness, substrate type, applied bias and post annealing have been measured and discussed. Radiation induced charge in MOS devices is shown to be a strong function of the oxide thickness as expected. Application of a positive bias to the gate is found to enhance the device sensitivity for both n- and p-type devices. This is explained in terms of the involvement of the interface states in the sensing process. Devices have also been studied after repeated cycles of irradiation and annealing treatment under hydrogen atmosphere. Each cycle consists of gamma irradiation with 60 Gray dose and an anneal at 200 °C for 30 min. The charging-discharging mechanism during these cycles is discussed.     

Diode Polarization and Resistive Switching in Metal/TlGaSe2 Semiconductor/Metal Devices

Semiconductors - The influence of electric field and current flow on the current–voltage (I–V) characteristics of TlGaSe2 layered semiconductor was investigated by using a two-point...     

Fracture resistance of roots obturated with a novel calcium silicate-based endodontic sealer (BioRoot RCS)

The aim of this ex vivo study was to evaluate the vertical-fracture resistance of roots obturated with a newly developed tricalcium silicate cement (BioRoot RCS; Septodont, Saint Maur Des Fosses, France) using cold lateral compaction technique (LC) or matched-taper single-cone gutta-percha technique (SC). Decoronated 82 single-rooted mandibular premolars were chemo-mechanically prepared and then randomly divided into 6 experimental groups (n = 12) and 2 control groups (n = 5): Group 1 iRoot SP-LC; Group 2 iRoot SP-SC; Group 3 MTA Fillapex-LC; Group 4 MTA Fillapex-SC; Group 5 BioRoot RCS-LC and Group 6 BioRoot RCS-SC. In the positive-control group, roots were instrumented but not filled, and in the negative-control group, roots were neither instrumented nor filled. All samples were incubated for two weeks and then subjected to vertical loading force (1 mm/min) until fracture. The force required to fracture each specimen were determined, and the data were statistically analyzed. The highest significant fracture resistance was recorded for the iRoot SP-LC, iRoot SP-SC, BioRoot RCS-LC, and BioRoot RCS-SC groups, with no significant difference among them (p > 0.05) when compared with the positive-control group (p < 0.05), whereas the lowest significant values were observed in the MTA Fillapex-LC and MTA Fillapex-SC groups (p < 0.05). The vertical fracture resistance of roots obturated with BioRoot RCS and iRoot SP sealers using either LC or SC technique was found to be similar to that of intact teeth. BioRoot RCS, newly developed tricalcium silicate cement, might have the potential to reinforce the instrumented teeth against vertical root fracture.     

Design of electrochemical biosensor systems for the detection of specific DNA sequences in PCR-amplified nucleic acids related to the catechol-O-methyltransferase Val108/158Met polymorphism based on intrinsic guanine signal

Psychiatric disorders are common and complex diseases that show polygenic and multifactorial heredity. A single nucleotide polymorphism (Val108/158Met) in the catechol-O-methyl transferase (COMT) gene is related to many psychiatric disorders such as schizophrenia, alcoholism, bipolar disorder, and obsessive-compulsive disorder. Schizophrenia is a complex disorder and a single nucleotide polymorphism (Val108/158Met) at the COMT gene is related to schizophrenia susceptibility. A novel hybridization-based disposable electrochemical DNA biosensor for the detection of a common functional polymorphism in the COMT gene from polymerase chain reaction (PCR) amplicons has been described without using an external label. This developed technology combined with a disposable carbon graphite electrode and differential pulse voltammetry was performed by using short synthetic oligonucleotides and PCR amplicons in length 203 bp to measure the change of guanine oxidation signal obtained at approximately +1.0 V after DNA hybridization between probe and target (synthetic target or denatured PCR samples). COMT-specific oligonucleotides were immobilized onto the carbon surface with a simple adsorption method in two different modes: (a) Guanine-containing targets were attached or (b) inosine-substituted probes were attached onto an electrode. By controlling the surface coverage of the target DNA, the hybridization event between the probes and their synthetic targets or specific PCR products was optimized. The wild-type or polymorphic allele-specific probes/targets were also interacted with an equal amount of noncomplementary and one-base mismatch-containing DNAs in order to measure the sensor selectivity. The decrease or appearance in the intrinsic guanine signal simplified the detection procedure and shortened the assay time because protocol eliminates the label-binding step. The nonspecific binding effects were minimized by using sodium dodecyl sulfate with different washing methods. The Val108/158Met COMT genotype detection were performed with real samples containing wild-type (healthy controls), polymorphic (mutant type), and heterozygous PCR products. The detection limit (S/N = 3) of the biosensor was 2.44 pmol of target sequence in the 30-muL samples. Analytical performance of the sensor is described, along with future prospects.     

Sensory and Physico‐Chemical Properties of Cold Press‐Produced Tomato (Lycopersicon esculentum L.) Seed Oils

In this study, roasted and unroasted (control) tomato seeds were cold pressed and the seeds, oils, and seed presscakes (meals) were analyzed. Some physicochemical properties, total phenolic content and antioxidant capacity, thermal properties, mineral contents, fatty acids, sterols and tocopherols compositions, volatile compounds and sensory evaluation of the tomato seed oils were determined. The tomato seeds contained 3.3 % of ash, 17.3 % of oil and 27.2 % of protein. The cold press oil recovery rate was 7.2 and 10.28 % for control and roasted seeds, respectively. There were eight sensory terms defining the oils together with 34 different aromatic compounds quantified. The volatile compounds furfural, hexanal, benzaldehyde and 2‐isobutylthiazole were found with the highest frequency in the samples. Roasted, green and tomato were defined as characteristic sensory terms for tomato seeds oils. Fifteen different minerals, melting and crystallization temperatures and enthalpies of the oil samples were also quantified. This study provides important data for the tomato seed oils, and proves that pre‐roasted tomato seed oils are high quality, nutritious and aromatics oils with higher levels of consumer acceptability.     

Nitric Oxide (NO) and Lactic Acid Bacteria-Contributions to Health, Food Quality, and Safety

In this article, the effects of nitric oxide (NO) and nitric oxide producer bacteria on food quality, safety, and human health care high lighted. NO, which was previously recognized as a toxic gas, has attracted attention in the last two decades due to its vital role in many physiological processes of animals and plants. Particularly, it is important to note from the point of view of food quality and safety that lactic acid bacteria, which are used as starter cultures in foods, also have the capability of producing NO. There have been several studies on the color development of meat products that originated from NO production of lactic acid bacteria. For this reason, it is also important to emphasize the different aspects of interactions between food and NO.     

Determination of thermal conductivities of solid and liquid phases for rich-Sn compositions of Sn-Mg alloy

The variations of thermal conductivities of solid phases versus temperature for pure Sn and Sn-1 wt% Mg, Sn-2 wt% Mg, and Sn-6 wt% Mg binary alloys were measured with a radial heat flow apparatus. Thermal conductivity variations versus temperature for pure Sn and Sn-1 wt% Mg, Sn-2 wt% Mg, and Sn-6 wt% Mg binary alloys were found to be 60.60 ± 3.63, 61.99 ± 3.71, 68.29 ± 4.09, and 82.04 ± 4.92 W/Km, respectively. The thermal conductivity ratios of liquid phase to solid phase for pure Sn and eutectic Sn-2 wt% Mg alloy at their melting temperature were found to be 1.11 and 1.08, respectively, with a Bridgman type directional solidification apparatus. Thus the thermal conductivities of liquid phases for pure Sn and eutectic Sn-2 wt% Mg binary alloy at their melting temperature were evaluated to be 67.26 ± 4.03 and 73.75 ± 4.42 W/Km, respectively, by using the values of solid phase thermal conductivities and the thermal conductivity ratios of the liquid phase to the solid phase.     

Self‐assembling chitosan hydrogel: A drug‐delivery device enabling the sustained release of proteins

The development of a self‐assembling hydrogel, prepared from maleimide‐modified and thiolated chitosan (CS), is described. Under mild reaction conditions, the natural CS polymer was coupled with either maleimide or sulfhydryl moieties in a one‐step synthesis. Subsequently, these CS polymers spontaneously formed a covalently crosslinked CS hydrogel when mixed. The three‐dimensional network structure was visualized with scanning electron microscopy. The swelling and degradation behavior was evaluated, and viscosity measurements were conducted. The gel was loaded with the model protein albumin, and prolonged release was achieved. These properties were preserved after lyophilization and rehydration. This makes the hydrogel a promising scaffold for biological wound dressings for the treatment of chronic wounds. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 45638.     

Enrichment of frying oils with plant phenolic extracts to extend the usage life

The aim of this research was to evaluate the efficacy of extracts prepared from olive leaf (OLVL), hazelnut leaf (HAZL), and hazelnut green leafy cover (HGLC) in frying conditions. The extracts were added into canola oil at 200 ppm phenolic equivalence level and fried for seven consecutive days and analyzed. Generally, the lowest phenolic content and antioxidant capacity value were measured in HGLC extract, although, the best performance during frying was with HGLC extract. There were significant differences among the free acidity, conjugated dienoic acids, and total polar materials (TPM). The oil enriched with HGLC extract did not exceed the limit TPM value at the end of seventh day. Also the remaining antioxidant capacities in the frying oil samples were highest in HGLC enriched samples. The viscosity and turbidity values of the oils enriched with OLVL and HAZL extract were a little higher than a control sample. Generally trans‐fatty acid formation was lower in the enriched oil samples. Also significant decreases in the level of unsaturated fatty acids during frying period were observed. This study shows that enriching oils with easily found and cheap natural plant extracts can extend their usage life. Practical applications: The results of this study have shown that liquid frying oils can successfully be enriched with plant phenolic extract to enhance thermo‐oxidative stability. Addition of phenolic extract up to 200 ppm level have not created any problem in sensory quality of either the oil or fried dough. The HGLC and OLVL extract were found very suitable for this purpose. These materials are common agro‐food by‐products and can be produced very easily with low cost. Also, this type of enrichment may aid consumers to get some beneficial phenolic compounds through fried food consumption. In addition, these types of applications may open another area for marketing the named plant extracts.     

Synthesis of antibacterial N-halamine acryl acid copolymers and their application onto cotton

A series of N-halamine copolymers are synthesized by reacting hydantoinylacrylamide (HA) with acrylic acid (AA) in several mole ratios. The synthesized copolymers are characterized by Fourier transform infrared (FTIR) and ¹H NMR and coated onto cotton fabrics. The coated cotton fabrics are rendered antibacterial by chlorinating with dilute household bleach solution. The ultraviolet (UVA) light stabilities of the resulting copolymers on the coated cotton fabrics are investigated; the results show that UVA exposure has minimal effect on the structure of the copolymers but can cause partial loss of the chlorine loading on the coated cotton fabrics. The coated cotton fabrics exhibit excellent antibacterial efficacies achieving inactivations of about six logs of Staphylococcus aureus and Escherichia coli O157:H7 within 1 min of contact time. The cotton fabrics coated with the copolymers would best be employed in disposable fabric applications because of lack of washing fastness due to the weak bonding interaction between the AA unit and cellulose. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47426.