Sterilization Applications Research Articles

A Study the Effect of TiO2 Nanoparticles Combination with Antibiotics and Plant extracts Against Some Gram Negative Bacteria

Titanium dioxide TiO2 has been widely utilized in cleaning and sterilizing material for many clinical tools sanitary ware, food tableware and cooking and items for use in hospitals. Titanium dioxide TiO2 non toxicity and long term physical and chemical stability. It has been widely used decomposition of organic compounds and microbial organisms such as cancer cell, viruses and bacteria as well as its potential application in sterilization of medical devices. The aim of the study the effect of titanium dioxide TiO2 on some Gram negative bacteria and study their effects on some virulence factors and chromosomal DNA.In this study, we obtained (E. coli ? Proteus mirabilis, Proteus vulgaris ? Pseudomonas aeruginosa ? Klebsiella pneumonia and Acinetobacter baumannii) from Al-Emamain Al-Kadhemain Medical City Hospital in Baghdad. Samples collection were carried out from 1 April to 30 June 2014. Study the effect of (plant extraction and Antibiotic) alone and combination with Titanium dioxide TiO2 on bacteria growth. And study the effect of Titanium dioxide TiO2 on biofilm layer and chromosomal DNA.Combinations of TiO2 nanoparticle with water and alcohol extracts of plant (Salvia officinalis ?Arctium minus, Origanum majorana and Anabasis syriaca) gave synergistic results against the gram negative bacterial isolates.A Synergism effect was observed in combination of Ciprofloxacin with Titanium TiO2 nanoparticles toward all Gram negative bacteria. Also a high efficiency was observed when TiO2 nanoparticles mixed with Amikacin toward all isolates except Acinetobacter baumannii and E. coli3. While the results of mixing TiO2 nanoparticles with Cephalothin indicate highly efficiency toward all isolates except Pseudomonas aeruginosa.The combination of plant extracts (Salvia officinalis ? Arctium minus ? Origanum majorana and Anabasis syriaca) with TiO2 nanoparticles was appear to be damaged to E. coli chromosomal DNA.The study showed the ability of nanoparticles TiO2 to inhibition of the layer Biofilm to all isolates of bacteria at concentrations (1, 1.5) µg/ ml.Conclude from this study we can be used TiO2 nanoparticles to kill some types of bacteria

(Invited) High Output Power Deep Ultraviolet Light-Emitting Diodes with Hemispherical Lenses Fabricated Using Room Temperature Bonding

AlGaN-based light-emitting diodes (LEDs) are attractive candidates for next-generation light sources in the deep ultraviolet (DUV) region because they can cover the spectral range of 210 – 365 nm through control of the Al content in the epitaxial layers. Moreover, they are environmentally friendly, having zero mercury content and a long lifetime. These excellent properties of AlGaN-based DUV LEDs are suitable for sterilization and polymer curing applications, however, their output power is not yet sufficient for practical applications. One method to improve output power of DUV LEDs is the enhancement of the light extraction efficiency from the LEDs chips to the air by connecting graded refractive index medium outside the chips. The refractive index medium should have the long-term reliability against DUV. We designed and fabricated the hemispherical lensmade of inorganic materials as a refractive index medium, and bonded the hemispherical lenses to the LEDs using room temperature bonding methods. We demonstrated high output power 255 nm and 280 nm LEDs with lenses [M. Ichikawa et al., APEX, to be contributed]. For this study, the excellent properties of fabricated LEDs with lenses are reviewed in connection with the bonded interface structure in light of new experimental data. The following figures (A) and (B) show schematic illustrations of LED chips and hemispherical lenses. We fabricated AlGaN-based 255 nm and 280 nm LEDs on sapphire substrates with a size of 1 mm square. A flip-chip type LED was produced to extract DUV light through the sapphire substrate. A simulation study predicted that the refractive index of the hemispherical lens was optimum when the lens was made of sapphire, which was the same material as that of LED substrates. Moreover, the light extraction efficiency was most enhanced when the lens diameter exceeded 3 mm. Therefore, we fabricated hemispherical lenses made of sapphire, with diameters of 3 or 5 mm. The LED chips were bonded to sapphire lenses at room temperature using two different bonding methods as shown in figure (C). One was surface activated bonding (SAB). In this method, the bonding surfaces of sapphire are sputter-etched and activated using an Ar fast ion beam. Transmission Electron Microscopy (TEM) images revealed that the surfaces of sapphire are consisted of several nanometer-thick amorphous layers, which were the damaged layers of the sapphire by the Ar ion beam irradiation. A large loading force was necessary to bond sapphire to sapphire. However, no light absorption was observed at the SAB interface. Another bonding method was atomic diffusion bonding (ADB). In this method, metal films are fabricated on two flat sapphire surfaces using sputter deposition with subsequent bonding of the two films on the sapphire in vacuum. Very thin Al films were used as the metal films for this study because the extinction coefficient of aluminum is small. A light absorption was slightly observed at the bonded interface in the DUV region. However, sapphire could be bonded without applying too high loading pressures. Moreover, ADB is applicable to bonding any mirror-polished substrates, in addition to sapphire, which is expected to extend the applications. The LEDs with lenses had higher light extraction efficiency than conventionally structured LEDs without lenses. In SAB devices, the maximum external quantum efficiency of the 255 nm LED was 4.56% at 100 mA, and that of the 280 nm LED was 10.1% at 1 A. As a result, at a forward current of 350 mA, the output power of a 255 nm LED with a lens increased by a factor 2.8, reaching 73.6 mW. Furthermore, that of the 280 nm LED increased by a factor of 2.3, reaching 153 mW. The output powers of ADB devices were also significantly higher than those of conventionally structured LEDs without lenses but were slightly lower than those of SAB devices because of a light absorption at the bonding interface. A further enhancement of output powers of ADB devices can be expected by tuning bonding process. The findings in this study would contribute not only to the research in DUV LEDs but also to the research of visible light LEDs. Figure 1

New insights on pressure, temperature, and chemical stability of CsAlSi5O12, a potential host for nuclear waste

A Cs-bearing polyphase aggregate with composition (in wt%): 76(1)CsAlSi5O12 + 7(1)CsAlSi2O6 + 17(1)amorphous, was obtained from a clinoptilolite-rich epiclastic rock after a beneficiation process of the starting material (aimed to increase the fraction of zeolite to 90 wt%), cation exchange and then thermal treatment. CsAlSi5O12 is an open-framework compound with CAS topology; CsAlSi2O6 is a pollucite-like material with ANA topology. The thermal stability of this polyphase material was investigated by in situ high-T X-ray powder diffraction, the combined P–T effects by a series of runs with a single-stage piston cylinder apparatus, and its chemical stability following the “availability test” (“AVA test”) protocol. A series of additional investigations were performed by WDS–electron microprobe analysis in order to describe the P–T-induced modification of the material texture, and to chemically characterize the starting material and the run products. The “AVA tests” of the polyphase aggregate show an extremely modest release of Cs+: 0.05 mg/g. In response to applied temperature and at room P, CsAlSi5O12 experiences an unquenchable and displacive Ama2-to-Amam phase transition at about 770 K, and the Amam polymorph is stable in its crystalline form up to 1600 K; a crystalline-to-amorphous phase transition occurs between 1600 and 1650 K. In response to the applied P = 0.5 GPa, the crystalline-to-amorphous transition of CsAlSi5O12 occurs between 1670 and 1770 K. This leads to a positive Clapeyron slope (i.e., dP/dT > 0) of the crystalline-to-amorphous transition. When the polyphase aggregate is subjected at P = 0.5 GPa and T > 1770 K, CsAlSi5O12 melts and only CsAlSi2O6 (pollucite-like; dominant) and Cs-rich glass (subordinate) are observed in the quenched sample. Based on its thermo-elastic behavior, P–T phase stability fields, and Cs+ retention capacity, CsAlSi5O12 is a possible candidate for use in the immobilization of radioactive isotopes of Cs, or as potential solid hosts for 137Cs γ-radiation source in sterilization applications. More in general, even the CsAlSi5O12-rich aggregate obtained by a clinoptilolite-rich epiclastic rock appears to be suitable for this type of utilizations.

Combined education and skin antisepsis intervention for persistently high blood-culture contamination rates in neonatal intensive care

Contaminated blood cultures represent challenges regarding diagnosis, duration of hospitalization, antimicrobial use, pharmacy and laboratory costs. Facing problematic neonatal blood culture contamination (3.8%), we instigated a successful intervention combining skin antisepsis using sterile applicators with 2% chlorhexidine gluconate in 70% isopropanol prior to phlebotomy (replacing 70% isopropanol) and staff education. In the six months prior to intervention, 364 neonatal peripheral blood samples were collected. Fourteen (3.8%) were contaminated. In the post-intervention six months, 314 samples were collected. Three (0.96%) were contaminated, representing significant improvement (Fisher's exact test: P=0.0259). No dermatological sequelae were observed. The improvement has been sustained.

Simulated Biophysical Experimental Techniques for Chlorhexidine in DMPC/Cholesterol Systems

Isothermal titration calorimetry and differential scanning calorimetry are essential biophysical techniques used to measure interactions of small molecules. We have investigated the use of molecular dynamic simulations and the MARTINI force field to simulate these two lab techniques. Our goal was to observe how well they can reproduce the concentration effects of the addition of the small molecule chlorhexidine into a model lipid system containing DMPC and varying concentrations of cholesterol.Chlorhexidine is a chemical antiseptic shown to be effective against a wide range of bacteria in products such as: surgical hand washes, mouthwash, industrial sterilization and many other similar applications. It acts specifically against the plasma membrane, causing leakage leading to cell death.We constructed a coarse grained model for chlorhexidine compatible with the MARTINI force field. Using the GROMACS simulation software we were able to mimic an isothermal titration calorimetry experiment by repeatedly adding a small concentration of chlorhexidine into a DMPC membrane. We observed a decreasing affinity between chlorhexidine and the membrane with increasing concentration as well as a resulting increase in the reaction time before the system was equilibrated.We then performed a controlled cooling of the systems to mimic a differential scanning calorimetry experiment. A sharp change in membrane structure accompanied by a spike in the specific heat was measured at specific temperature Tm signaling a phase transition. We then varied the concentration of chlorhexidine as well as the addition of varying concentrations of cholesterol to observe trends in the change to Tm due to the addition of the cholesterol and chlorhexidine.

Falope Rings or Modified Pomeroy's Technique for Concurrent Tubal Sterilization.

Sterilization at caesarean section is usually performed by the modified Pomeroy's technique. Application of Falope rings and Filshie clips may also be used for tubal sterilization at caesarean section, and these techniques are also used during laparoscopy or minilaparotomy. The main objective of the study was to evaluate the failure rates, complications, technical difficulties and reversibility of the Falope ring application for tubal sterilization as compared to the traditional modified Pomeroy's technique used during caesarean sections. Five hundred multigravid women who underwent caesarean section for various causes and wanted concurrent tubal sterilization were recruited in the study. Two hundred and fifty women underwent tubal sterilization by Falope ring application and the other 250 by modified Pomeroy's technique. Follow-up period ranged from 3 to 42months. These patients' names were checked against the antenatal booking register, the operating theatre register in case of ectopic pregnancies and a termination of pregnancy register to recognize failed sterilization. Among the 250 women who underwent Falope ring application, no major complications were noted. In the other group, women who underwent tubal sterilization by modified Pomeroy's technique, there was one woman with serious complication, ectopic pregnancy. Falope ring application was an easy procedure to perform and also less time-consuming than modified Pomeroy's technique. Falope ring sterilization is simple, effective and safe, and the rate of subsequent pregnancy is lower than with conventional modified Pomeroy's technique.

A Study the Effect of TiO2 Nanoparticles Combination with Antibiotics and Plant extracts Against Some Gram Negative Bacteria

Titanium dioxide TiO2 has been widely utilized in cleaning and sterilizing material for many clinical tools sanitary ware, food tableware and cooking and items for use in hospitals. Titanium dioxide TiO2 non toxicity and long term physical and chemical stability. It has been widely used decomposition of organic compounds and microbial organisms such as cancer cell, viruses and bacteria as well as its potential application in sterilization of medical devices. The aim of the study the effect of titanium dioxide TiO2 on some Gram negative bacteria and study their effects on some virulence factors and chromosomal DNA.In this study, we obtained (E. coli ? Proteus mirabilis, Proteus vulgaris ? Pseudomonas aeruginosa ? Klebsiella pneumonia and Acinetobacter baumannii) from Al-Emamain Al-Kadhemain Medical City Hospital in Baghdad. Samples collection were carried out from 1 April to 30 June 2014. Study the effect of (plant extraction and Antibiotic) alone and combination with Titanium dioxide TiO2 on bacteria growth. And study the effect of Titanium dioxide TiO2 on biofilm layer and chromosomal DNA.Combinations of TiO2 nanoparticle with water and alcohol extracts of plant (Salvia officinalis ?Arctium minus, Origanum majorana and Anabasis syriaca) gave synergistic results against the gram negative bacterial isolates.A Synergism effect was observed in combination of Ciprofloxacin with Titanium TiO2 nanoparticles toward all Gram negative bacteria. Also a high efficiency was observed when TiO2 nanoparticles mixed with Amikacin toward all isolates except Acinetobacter baumannii and E. coli3. While the results of mixing TiO2 nanoparticles with Cephalothin indicate highly efficiency toward all isolates except Pseudomonas aeruginosa.The combination of plant extracts (Salvia officinalis ? Arctium minus ? Origanum majorana and Anabasis syriaca) with TiO2 nanoparticles was appear to be damaged to E. coli chromosomal DNA.The study showed the ability of nanoparticles TiO2 to inhibition of the layer Biofilm to all isolates of bacteria at concentrations (1, 1.5) µg/ ml.Conclude from this study we can be used TiO2 nanoparticles to kill some types of bacteria

Bacteria sterilization application by using plasma activated physiological saline

The plasma activated water has great application prospects in the fields of environmental protection, biomedicine, food safety, et al., due to its unique chemical activity. In this work, the plasma activated physiological saline is successfully generated by using hollow fiber-based cold microplasma jet array running in physiological saline solution. This design can lead to an obvious increase in the contact area between microplasmas and treated physiological saline solution, thus improving the chemical reaction efficiency of short-lived species. The influences of working gases such as He, N2, O2 and air on the sterilization efficiency of E. Coli by using this plasma activated physiological saline are investigated as a function of discharge time. As the discharge time increases from 10 to 180 s, the sterilization efficiency of the plasma activated physiological saline significantly increases. It is found that the bactericidal efficiency of the air discharge activated physiological saline is highest. For a discharge time of 120 s, the sterilization efficiency of E. Coli in this plasma activated physiological saline can reach as high as 99.999%. The pH value of this air discharge activated physiological saline is achieved by using acidity meter and as the discharge time increases from 10 to 60 s, the pH value decreases from 7.3 to 3.1 and the physiological solution becomes acidic. This may be due to the NOX produced in the plasma reacting with water and producing nitric and nitrate acids. The reactive oxygen species generated in the plasma activated physiological saline are supposed to be O3 and H2O2. The concentrations of O3 and H2O2 are identified by using UV-visible absorption spectra and chemical deposition methods. The strong absorption peak of O3 in UV-visible absorption spectrum is at a wavelength of 253.7 nm. The concentration of O3 is calculated by using Beer-Lambert Law. As the discharge time increases, the concentration of O3 in the plasma activated physiological saline obviously increases. For a discharge time of 60 s, the concentration of O3 is 43.1210-3 mol/L and nearly saturated. The concentration of H2O2 is obtained by the total amount of reactive oxygen species, which is calculated by using the chemical deposition method, deducting the O3 content. As the discharge time increases from 10 to 180 s, the concentration of H2O2 increases from 1.510-3 to 4.710-3 mol/L. The analyses of experimental data from various methods indicate that air discharge activated physiological saline containing a variety of long-lived reactive oxygen species, such as H2O2 and O3, is very effective in killing E. Coli cells in the acidic saline solution. The air discharge activated physiological saline can provide a means to store the advanced oxidation species induced by the discharge for sterilization applications.

Candida colonization of the vagina of HIV-seropositive pregnant women and their seronegative counterparts at selected health-care centers in Akure, Ondo State, Nigeria

Background: Candida colonization of the vagina is a risk factor in pregnancy. Candida isolates have been implicated in adverse pregnancy outcomes. The study determined the incidence of Candida species recovered from the vagina of HIV-seropositive and HIV-seronegative pregnant women that attended antenatal clinics in Akure, Ondo State between November 2014 and December 2015. Materials and Methods: Two hundred and forty pregnant women aged 19–43 participated in the study, which included 114 HIV-seropositive subjects with mean age 31.81 years and 126 HIV-seronegative subjects with mean age 29.05 years as controls. High vaginal swab was collected from each subject using sterile cotton-tipped applicator, streaked onto Mycological Agar - supplemented with streptomycin. Each sample was incubated 24 h for yeast and 72–120 h for the growth of molds. Yeast colonies that grew on Mycological Agar were picked and studied. Thereafter, colonies resembling Candida were identified using sugar assimilation and fermentation. Candida isolates were further speciated using Candida Ident Agar, modified. Antifungal resistance profile was identified with azoles, polyenes, echinocandins, flucytosine, and griseofulvin drugs. Antifungal resistant assay was determined by disc and agar well diffusion. Results: Altogether, 157 Candida isolates were recovered from HIV-seropositive and HIV-seronegative subjects. Candida albicans constituted 46.5%, Candida dubliniensis and Candida glabrata 15.3% each, Candida krusei 12.1%, Candida spp. 5.7%, and Candida tropicalis and Candida pseudotropicalis 2.5% each. Antifungal resistance was widespread with azoles, polyenes, echinocandins, flucytosine, and griseofulvin. Conclusion: C. albicans was the predominant isolate recovered (17.2% HIV-seropositive and 29.3% HIV-seronegative subjects). Widespread antifungal resistance seems high and suggests possible abuse of these drugs.

Mechanism of Bacillus subtilis spore inactivation by and resistance to supercritical CO2 plus peracetic acid.

Determine how supercritical CO2 (scCO2 ) plus peracetic acid (PAA) inactivates Bacillus subtilis spores, factors important in spore resistance to scCO2 -PAA, and if spores inactivated by scCO2 -PAA are truly dead. Spores of wild-type B.subtilis and isogenic mutants lacking spore protective proteins were treated with scCO2 -PAA in liquid or dry at 35°C. Wild-type wet spores (aqueous suspension) were more susceptible than dry spores. Treated spores were examined for viability (and were truly dead), dipicolinic acid (DPA), mutations, permeability to nucleic acid stains, germination under different conditions, energy metabolism and outgrowth. ScCO2 -PAA-inactivated spores retained DPA, and survivors had no notable DNA damage. However, DPA was released from inactivated spores at a normally innocuous temperature (85°C), and colony formation from treated spores was salt sensitive. The inactivated spores germinated but did not outgrow, and these germinated spores had altered plasma membrane permeability and defective energy metabolism. Wet or dry coat-defective spores had increased scCO2 -PAA sensitivity, and dry spores but not wet spores lacking DNA protective proteins were more scCO2 -PAA sensitive. These findings suggest that scCO2 -PAA inactivates spores by damaging spores' inner membrane. The spore coat provided scCO2 -PAA resistance for both wet and dry spores. DNA protective proteins provided scCO2 -PAA resistance only for dry spores. These results provide information on mechanisms of spore inactivation of and resistance to scCO2 -PAA, an agent with increasing use in sterilization applications.

Influences of the steam sterilization on the properties of calcium phosphate porous bioceramics.

The influences of steam sterilization on the physicochemical properties of calcium phosphate (Ca-P) porous bioceramics, including β-tricalcium phosphate (β-TCP), biphasic calcium phosphate (BCP) and hydroxyapatite (HA) are investigated. After being steam sterilized in an autoclave (121 °C for 40 min), the porous bioceramics are dried and characterized. The steam sterilization has no obvious effects on the phase composition, thermal stability, pH value and dissolubility of β-TCP porous bioceramic, but changes its morphology and mechanical strength. Meanwhile, the steam sterilization leads to the significant changes of the morphology, phase composition, pH value and dissolubility of BCP porous bioceramic. The increase of dissolubility and mechanical strength, the decrease of pH value of the immersed solution and partial oriented growth of crystals are also observed in HA porous bioceramic after steam sterilization. These results indicate that the steam sterilization can result in different influences on the physicochemical properties of β-TCP, BCP and HA porous bioceramics, thus the application of the steam sterilization on the three kinds of Ca-P porous bioceramics should be considered carefully based on the above changed properties.

Propagation characteristics of atmospheric-pressure He+O2 plasmas inside a simulated endoscope channel

Cold atmospheric-pressure plasmas have potential to be used for endoscope sterilization. In this study, a long quartz tube was used as the simulated endoscope channel, and an array of electrodes was warped one by one along the tube. Plasmas were generated in the inner channel of the tube, and their propagation characteristics in He+O2 feedstock gases were studied as a function of the oxygen concentration. It is found that each of the plasmas originates at the edge of an instantaneous cathode, and then it propagates bidirectionally. Interestingly, a plasma head with bright spots is formed in the hollow instantaneous cathode and moves towards its center part, and a plasma tail expands through the electrode gap and then forms a swallow tail in the instantaneous anode. The plasmas are in good axisymmetry when [O2] ≤ 0.3%, but not for [O2] ≥ 1%, and even behave in a stochastic manner when [O2] = 3%. The antibacterial agents are charged species and reactive oxygen species, so their wall fluxes represent the “plasma dosage” for the sterilization. Such fluxes mainly act on the inner wall in the hollow electrode rather than that in the electrode gap, and they get to the maximum efficiency when the oxygen concentration is around 0.3%. It is estimated that one can reduce the electrode gap and enlarge the electrode width to achieve more homogenous and efficient antibacterial effect, which have benefits for sterilization applications.

Use of Silver Nanoparticles Reduces Internal Contamination of External Hexagon Implants by Candida albicans.

Since the dental implant/abutment interface cannot totally seal the passage of microorganisms, the interior of implant becomes a reservoir of pathogenic microorganisms that produce and maintain chronic inflammation in the tissues around implants. Silver nanoparticles (nano-Ag) are potent and broad-spectrum antimicrobial agents. The aim of this study was to evaluate the capacity of the nano-Ag to prevent the contamination of the implant internal surface by Candida albicans, caused by the implant/abutment microgap infiltration. Thirty-six implants were used in this experiment. Three study groups were performed: experimental group (implants receiving an application of nano-Ag in their inner cavity before installation of the abutment); positive-control group (implants receiving sterile phosphate buffer saline application instead of nano-Ag) and negative-control group (implants receiving the application of nano-Ag in the inner cavity and immersed in a sterile medium). In the positive-control and experimental groups, the implants were immersed in a Candida albicans suspension. The abutments of all three groups were screwed with a 10 N torque. After 72 h of immersion inC. albicans suspension or sterile medium, the abutments were removed and the inner surface of the implants was sampled with absorbent paper cone for fungal detection. No C. albicans contamination was observed in the negative-control group. The positive-control group showed statistically higher values of colony forming units (CFUs) of C. albicans compared with the experimental group. In conclusion, silver nanoparticles reduced C. albicans colonization inside the implants, even with low torque screw abutment.

Volumetric solar heating of nanofluids for direct vapor generation

Traditional solar–thermal receivers suffer from high surface temperatures, which increase heat losses to the surroundings. To improve performance, volumetric receivers based on nanoparticles suspended in liquid (nanofluids) have been studied as an approach to reduce surface losses by localizing high temperatures to the interior of the receiver. Here, we report measured vapor generation efficiencies of 69% at solar concentrations of 10sun using graphitized carbon black, carbon black, and graphene suspended in water, representing a significant improvement in both transient and steady-state performance over previously reported results. To elucidate the vapor generation mechanism and validate our experimental results, we develop numerical and analytical heat transfer models that suggest that nanofluid heating and vapor generation occur due to classical global heating of the suspension fluid. This work demonstrates high nanofluid-assisted vapor generation efficiencies with potential applications in power generation, distillation, and sterilization.

The Emergence of Genetic Counseling in Sweden: Examples from Eugenics and Medical Genetics.

This paper examines the intertwined relations between eugenics and medical genetics from a Swedish perspective in the 1940s and 1950s. The Swedish case shows that a rudimentary form of genetic counseling emerged within eugenic practices in the applications of the Swedish Sterilization Act of 1941, here analyzed from the phenomenon of "heredophobia" (ärftlighetsskräck). At the same time genetic counseling also existed outside eugenic practices, within the discipline of medical genetics. The paper argues that a demand for genetic counseling increased in the 1940s and 1950s in response to a sense of reproductive responsibility engendered by earlier eugenic discourse. The paper also questions the claim made by theoreticians of biopolitics that biological citizens have emerged only during the last decades, especially in neoliberal societies. From the Swedish case it is possible to argue that this had already happened earlier in relation to the proliferation of various aspects of eugenics to the public.

A novel generator for high-voltage bipolar square pulses with applications in sterilization of microorganism

In this paper, we propose and design a novel generator for the high voltage square pulses with the changeable polarities in order to reach the requirements and the needs for the intended experiments on sterilization of microorganism. The major component of our circuits is a non-trivial combination between a half bridge Marx generator and an H bridge in series, combining with the DSP control unit, which can adjust the voltages, frequencies, pulse widths and polarities, and also tolerate various loads. More precisely, we illustrate the design and operation principles for each module in the constructed circuit and analyze the system performance with various loads. The effectiveness and correctness of our proposed circuit and methodologies have been verified and demonstrated by both PSIM simulation results and our own prototype. In this paper, we also show the stability and reliability of the pulse generator we proposed in terms of various load conditions and operation safety respectively. Furthermore, we also observe that the key parameters based on our constructed pulse generator can be easily adjusted which include voltages, frequencies, pulse widths and polarities. We hope that our work will stimulate the further investigations on design and analysis of pulse generators with a focus on modularization and miniaturization.

Pulsed light sterilization of packaging materials

Abstract Pulsed light (PL) technology is an emerging processing method that utilizes short duration pulses of intense, broad-spectrum light for the sterilization of surface. Compared to other sterilization methods, such as heat or chemical disinfectant treatment, PL treatment has several advantages; it is faster and leaves no residues. This review discusses the sterilization principles behind PL and its applications for surface sterilization, in especially the decontamination of food packaging materials. The efficacy of PL treatment can be affected by several factors, including the low penetration ability of PL, the shadowing effect of microorganisms, and the composition and properties of the surfaces. The mechanism of microbial inactivation by PL are also summarized. To increase the efficacy of sterilization, PL treatment in combination with chemicals or other decontamination techniques and their applications are also discussed. A complete understanding of the mechanisms of microbial decontamination and the hermetic effects of PL would provide clues on how to increase the efficiency and benefits of this technology for food industry applications.

Recent Progress in AlGaN‐Based Deep‐UV LEDs

SUMMARYDeep‐ultraviolet (DUV) light‐emitting diodes (LEDs) are in demand for a wide variety of potential applications, such as sterilization, water and air purification, medical uses, and so on. We have demonstrated 222–351 nm AlGaN and quaternary InAlGaN‐based DUV‐LEDs by developing a low threading dislocation density (TDD) AlN crystal. We achieved an external quantum efficiency (EQE) of about 4% and an output power greater than 30 mW in DUV‐LEDs for use in sterilization applications by developing new crystal growth techniques.

The application of lesion sterilization and tissue repair 3Mix-MP for treating rat's dental pulp tissue

Background: Lesion sterilization and tissue repair (LSTR) 3Mix-MP are three broad-spectrum antibiotics, including metronidazole, ciprofloxacin and minocycline are mixed with propylene glycol or macrogol. There is the possibility ofthe healing process that marked proliferation ofnew blood vessels and proliferation offibroblasts in the treatment ofirreversible pulpitis by pulp capping LSTR 3MixMP because of the principle of the method LSTR 3Mix-MP is to kill bacteria. Purpose: The purpose of this study to prove the effect of LSTR 3Mix-MP on chronic inflammation and the healing process in rat dental pulp tissue in vivo. Methods: Rattus norvegicus anaesthetized by using ketamine and xylazine dissolved in sterile isotonic saline solution (0.2 ml/50gr mm) on the upper right thigh. Cavity preparation class I to perforation by using a low speed tapered diamond round bur. In the treatment group, rats were treated 3Mix-MP at a dose of10 mg and then covered with glass ionomer cement for 7 days on the pulp that has been opened for 3 days. The control group treated with saline irrigation on the pulp that has been opened for 3 days. Rats were killed after seven days, and then made preparations pulp tissue to count the number oflymphocytes, macrophages, plasma cells, blood vessels, and fibroblasts Results: There is an increase in the average number ofmacrophage cells, plasma, and fibroblasts; and decreased lymphocytes and blood vessels in the treated group exposure LSTR 3Mix-MP. Conclusion: LSTR 3Mix-MP can reduce chronic inflammation process and enhance the healing process in rat dental pulp tissue.

Combination irradiation treatments for food safety and phytosanitary uses

Purpose of the review: Combination of irradiation treatment with other preservation techniques is of potential importance in enhancing the effectiveness and reducing the energy or dose requirement for destroying food borne illness and spoilage organisms while retaining or improving product quality. Phytosanitary irradiation to control quarantine pests, particularly insects, in traded fresh commodities may also benefit from combination with other disinfestation techniques to enhance effectiveness, and to reduce costs, treatment time, and product damage. Main findings: Combined preservation treatments can be beneficial to eliminate pathogenic bacteria due to the synergistic or additive effect of the treatments. It also permits less extreme use of a single treatment which may protect the sensory quality of the foods. Combination with modified atmosphere packaging (MAP), refrigeration, freezing or heating has great potential for improving the quality and the safety of fresh and processed foods. Irradiation and heat treatments reduce the numbers of pathogenic bacteria and the level of normal flora, while MAP and cold suppresses the growth of the survivors during subsequent storage. The use of natural antimicrobials at concentrations that do not affect the sensory qualities can increase the relative sensitivity of bacteria by >4-fold and can reduce the radiation dose necessary to eliminate pathogens. Natural antimicrobials are normally not stable over time; microencapsulation and the use of edible coatings can improve stability of antimicrobial formulations and prolong their bioactivity. Phytosanitary irradiation doses to control insects (50 to 400 Gy) are relatively low compared to doses for food safety and sterilization applications. Lowering doses further could save money on treatment costs by reducing treatment time, increasing the capacity of irradiation facilities, and reducing any problems with commodity quality. Combining irradiation with other insect disinfestation modalities such as cold, heat, fumigation, modified atmospheres, and chemical insecticides is a possible means to reduce the radiation dose, and the duration, level, or concentration of the companion treatment while meeting the technical objectives of the quarantine treatment. Irradiation in combination with cold is particularly promising, as it may be a means to reduce the duration and therefore costs of current cold treatment protocols. Irradiation may also allow use of higher cold temperatures that do not cause chilling injury in cold-sensitive fruits. Directions for future research: The efficacy of active edible coating and active biodegradable packaging in combination with irradiation for microbial control needs further investigation and should be demonstrated at the industrial level. The use of combined treatments to eliminate viruses and parasites in food is not well studied and should be investigated. The effects of mild heat treatment before irradiation on insect radiotolerance and bacteria radiosensitization should be investigated. The relationship between MAP packaging and insect radiation tolerance needs to be explored for a wider variety of quarantine pest species, including surface pests and inherently tolerant Lepidoptera and mites. Additional research is needed to demonstrate the efficacy of irradiation plus cold combination treatments against insects in fresh produce while assessing commodity quality and the potential for commercial application.