Inside‐out Ultraviolet‐C Sterilization of Pseudomonas aeruginosa Biofilm In Vitro

Biofilms are difficult to eradicate due to a protective architecture and create major challenges in patient care by diminishing both host immune response and therapeutic approaches. This study investigated a new strategy for treating surface‐attached biofilms by delivering germicidal UV through a material surface in a process referred to as “inside‐out sterilization” (IOS). Mature Pseudomonas aeruginosa (ATCC^® 27853^?) biofilms were irradiated with up to 1400 mJ cm^?2 of germicidal UV from both ambient and IOS configurations. The lethal dose for the ambient exposure group was 461 mJ cm^?2 95% CI [292, 728] compared to the IOS treatment group of 247 mJ cm^?2 95% CI [187, 325], corresponding to 47% less UV dosage for the IOS group (P < 0.05). This study demonstrated that with IOS, a lower quantal dosage of UV energy is required to eradicate biofilm than with ambient exposure by leveraging the organizational structure of the biofilm.     

Field Study and Evaluation of KrCl* Far UV-C Device Capability for Inactivation of Phi6 Bacteriophage

“Far UV-C” is an effective disinfection method that can be deployed in occupied areas. Commercially available Krypton Chloride (KrCl*) excimer lamps filtered to emit at 222 nm are effective in disinfecting pathogens and safe for human exposure up to an allowable threshold exposure, which is much longer than for conventional UV lamps emitting at 254 nm. Laboratory and controlled field testing of a filtered KrCl* excimer lamp for disinfection of a virus suspended in a thin film aqueous solution in an occupied office setting was conducted. Complete inactivation of almost 6 log (99.9999%) of Phi6 bacteriophage virus was achieved in ~20 min of exposure time in a field setting, equivalent to a dose of about 10 mJ cm⁻². The Phi6 inactivation rate constant for the field test results were not statistically different from laboratory values (P > 0.05, paired t-test). When positioned at 1 m distance from possible human exposure, this device can be used safely for almost 4.5 h of continuous direct exposure without any acute or long-term adverse health effects. This study illustrates the applicability and deployment of Far UV-C for pathogen reduction and can help in decision making for implementation of Far UV-C for disinfection in human-occupied environments.     

Novel Photobleachable Deep UV Resists Based on Single Component Nonchemically Amplified Resist System

Summary: Photobleachable deep UV resists were designed by introducing diazoketo groups in polymer side chains. The diazoketo groups undergo the Wolff rearrangement upon irradiation in the deep UV, affording ketenes that react with water to provide base‐soluble photoproducts. The polymers were synthesized by radical copolymerization of 2‐(2‐diazo‐3‐oxo‐butyryloxy)‐ethyl methacrylate, 2‐hydroxyethyl methacrylate, and γ‐butyrolacton‐2‐yl methacrylate. The single component resist showed 0.7 µm line and space patterns using a mercury‐xenon lamp in a contact printing mode.

Scanning electron micrograph of 0.7 µm line and space patterns printed with polymer B at a dose of 70 mJ · cm⁻².     

Dual-functional photocatalysis boosted by electrostatic assembly of porphyrinic metal-organic framework heterojunction composites with CdS quantum dots

Photocatalytic dual-functional reaction under visible light irradiation represents a sustainable development strategy. In detail, H₂ production coupled with benzylamine oxidation can remarkably lower the cost by replacing sacrificial agents. In this work, Cd S quantum dots(Cd S QDs) were successfully loaded onto the surface of a porphyrinic metal-organic framework(Pd-PCN-222) by the electrostatic selfassembly at room temperature. The consequent Pd-PCN-222/CdS heterojunction composites...     

Molecular structure and photosensitivity of polyesters with conjugated double bonds

Photocrosslinkable polyesters of m- and p-phenylenebis(α-cyanoacrylic acids) ( I-a and I-b ), m- and p-phenylenebis(α-cyanobutadiene carboxylic acids) ( I-d and I-e ), p-phenylenebis(acrylic acid) ( I-c ), and p-phenylenebis(butadiene carboxylic acid) ( I-f ) were prepared, and their photosensitivities were investigated. The spectral sensitivities of I-a , I-c , I-d , and I-e ranged up to 365, 385, 510, and 560 nm, respectively. This order corresponds to that of λ_max due to the π-π^* transition in their absorption spectra. I-e was sensitive to the visible part of argon ion laser even in the absence of photosensitizer. The highest sensitivity observed with I-e was estimated to be 1.5 mJ/cm². In contrast, the sensitivity of I-c was low (> 10⁵ mJ/cm²) and that of I ′- d , a modified I-d , was 1300 mJ/cm², respectively. Addition of 2,6-di(4′-methoxyphenyl)-4-(4′-n-amyloxyphenyl)thiapyrylium perchlorate to them extended their sensitivity range, improving their sensitivity values to 35 and 110 mJ/cm², respectively.     

Metal Oxide Nanostructures Generated from In Situ Sacrifice of Zinc in Bimetallic Textures as Flexible Ni/Fe Fast Battery Electrodes

An “in situ sacrifice” process was devised in this work as a room‐temperature, all‐solution processed electrochemical method to synthesize nanostructured NiO_x and FeO_x directly on current collectors. After electrodepositing NiZn/FeZn bimetallic textures on a copper net, the zinc component is etched and the remnant nickel/iron are evolved into NiO_x and FeO_x by the “in situ sacrifice” activation we propose. As‐prepared electrodes exhibit high areal capacities of 0.47 mA h cm⁻² and 0.32 mA h cm⁻², respectively. By integrating NiO_x as the cathode, FeO_x as the anode, and poly(vinyl alcohol) (PVA)‐KOH gel as the separator/solid‐state electrolyte, the assembled quasi‐solid‐state flexible battery delivers a volumetric capacity of 6.91 mA h cm⁻³ at 5 mA cm⁻², along with a maximum energy density of 7.40 mWh cm⁻³ under a power density of 0.27 W cm⁻³ and a maximum tested power density of 3.13 W cm⁻³ with a 2.17 mW h cm⁻³ energy density retention. Our room‐temperature synthesis, which only consumes minute electricity, makes it a promising approach for large‐scale production. We also emphasize the in situ sacrifice zinc etching process used in this work as a general strategy for metal‐based nanostructure growth for high‐performance battery materials.     

Ion conductive poly(ethylene oxide-dimethyl siloxane) copolymers

A series of poly(ethylene oxide-dimethyl siloxane) copolymers, — [SiMe₂O(CH₂CH₂O)_n]_m — (n = 2, 3, 4, 5, 6.4, 8.7, 13.3), were synthesised by the reaction of polyethylene glycol with dimethyl dimethoxy/diethoxysilane. Corresponding ion-conductive polymers were prepared by complexing these copolymers with salts (sodium tetrafluoroborate or ammonium adipate). The highest conductivity of these systems at room temperature was 3 × 10⁻⁴ S cm⁻¹ and 6 × 10⁻⁵ S cm⁻¹, respectively. The glass transition temperature of these copolymers is reported and is seen to be dependent on the length of the ether units. The effects of siloxane content, salt concentration, and temperature on the conductivity are discussed. © 1996 John Wiley & Sons, Inc.     

Temperature dependence of the rate coefficients for the reaction of chlorine atoms with chloromethanes

Rate coefficients for the reaction of Cl atoms with CH₃Cl (k₁), CH₂Cl₂ (k₂), and CHCl₃ (k₃) have been determined over the temperature range 222–298 K using standard relative rate techniques. These data, when combined with evaluated data from previous studies, lead to the following Arrhenius expressions (all in units of cm³ molecule⁻¹ s⁻¹): k₁ = (2.8 ± 0.3) × 10⁻¹¹ exp(−1200 ± 150/T); k₂ = (1.5 ± 0.2) × 10⁻¹¹ exp(−1100 ± 150/T); k₃ = (0.48 ± 0.05) × 10⁻¹¹ exp(−1050 ± 150/T). Values for k₁ are in substantial agreement with previous measurements. However, while the room temperature values for k₂ and k₃ agree with most previous data, the activation energies for these rate coefficients are substantially lower than previously recommended values. In addition, the mechanism of the oxidation of CH₂Cl₂ has been studied. The dominant fate of the CHCl₂O radical is decomposition via Cl‐atom elimination, even at the lowest temperatures studied in this work (218 K). However, a small fraction of the CHCl₂O radicals are shown to react with O₂ at low temperatures. Using an estimated value for the rate coefficient of the reaction of CHCl₂O with O₂ (1 × 10⁻¹⁴ cm³ molecule⁻¹ s⁻¹), the decomposition rate coefficient for CHCl₂O is found to be about 4 × 10⁶ s⁻¹ at 218 K, with the barrier to its decomposition estimated at 6 kcal/mole. As part of this work, the rate coefficient for Cl atoms with HCOCl was also been determined, k₇ = 1.4 × 10⁻¹¹ exp(−885/T) cm³ molecule⁻¹ s⁻¹, in agreement with previous determinations. © 1999 John Wiley & Sons, Inc. Int J Chem Kinet 31: 515–524, 1999     

Rate constants for the gas‐phase reactions of Cl atoms with a series of ethers

The laser photolysis–resonance fluorescence technique has been used to determine the absolute rate coefficient for the Cl atom reaction with a series of ethers, at room temperature (298 ± 2) K and in the pressure range 15–60 Torr. The rate coefficients obtained (in units of cm³ molecule⁻¹ s⁻¹) are dimethyl ether (1.3 ± 0.2) × 10⁻¹⁰, diethyl ether (2.5 ± 0.3) × 10⁻¹⁰, di‐n‐propyl ether (3.6 ± 0.4) × 10⁻¹⁰, di‐n‐butyl ether (4.5 ± 0.5) × 10⁻¹⁰, di‐isopropyl ether (1.6 ± 0.2) × 10⁻¹⁰, methyl tert‐butyl ether (1.4 ± 0.2) × 10⁻¹⁰, and ethyl tert‐butyl ether (1.5 ± 0.2) × 10⁻¹⁰. The results are discussed in terms of structure–reactivity relationship. © 2000 John Wiley & Sons, Inc. Int J Chem Kinet 32: 105–110, 2000     

Synthesis and characterization of novel photosensitive polyimide based on 5‐(2,5‐dioxotetrahydrofuryl)‐3‐methyl‐3‐cyclohexene‐1,2‐dicarboxylic anhydride

A negative type photosensitive polyimide with alicyclic moiety (NPI) was synthesized from 5‐(2,5‐dioxotetrahydrofuryl)‐3‐methyl‐3‐cyclohexene‐1,2‐dicarboxylic anhydride and 4,4‐diaminobenzophenone by one‐step polymerization in m‐cresol. Properties of the polyimides were characterized and a photo‐crosslinking mechanism was investigated using DEPT ¹³C‐NMR and FT‐IR spectroscopy. The negative polyimide showed good photosensitivity on exposure to UV light from a mercury xenon lamp. The polyimide showed remarkable solubility difference after photo‐ irradiation with an exposure dose of 500 mJ/cm². The resulting negative pattern of the photo‐cured NPI exhibited 10 μm resolution. Glass transition temperature of the photo‐crosslinked polyimide was about 307°C, which increased by 10°C compared to that of the polyimide before UV exposure. Transmittance of NPI after photo‐irradiation was about 87% at 500 nm. Copyright © 2004 John Wiley & Sons, Ltd.     

UV Inactivation of Common Pathogens and Surrogates Under 222 nm Irradiation from KrCl* Excimer Lamps

Germicidal ultraviolet (UV) devices have been widely used for pathogen disinfection in water, air, and on food and surfaces. Emerging UV technologies, like the krypton chloride (KrCl*) excimer emitting at 222 nm, are rapidly gaining popularity due to their minimal adverse effects on skin and eyes compared with conventional UV lamps emitting at 254 nm, opening opportunities for UV disinfection in occupied public spaces. In this study, inactivation of seven bacteria and five viruses, including waterborne, foodborne and respiratory pathogens, was determined in a thin-film aqueous solution using a filtered KrCl* excimer emitting primarily at 222 nm. Our results show that the KrCl* excimer can effectively inactivate all tested bacteria and viruses, with most microorganisms achieving more than 4-log (99.99%) reduction with a UV dose of 10 mJ cm⁻². Compared with conventional UV lamps, the KrCl* excimer lamp exhibited better disinfection performance for viruses but was slightly less effective for bacteria. The relationships between UV sensitivities at 222 and 254 nm for bacteria and viruses were evaluated using regression analysis, resulting in factors that could be used to estimate the KrCl* excimer disinfection performance from well-documented UV kinetics using conventional 254 nm UV lamps. This study provides fundamental information for pathogen disinfection when employing KrCl* excimers.     

Photoinactivation of Moraxella catarrhalis Using 405-nm Blue Light: Implications for the Treatment of Otitis Media

Moraxella catarrhalis is one of the major otopathogens of otitis media (OM) in childhood. M. catarrhalis tends to form biofilm, which contributes to the chronicity and recurrence of infections, as well as resistance to antibiotic treatment. In this study, we aimed to investigate the effectiveness of antimicrobial blue light (aBL; 405 nm), an innovative nonpharmacological approach, for the inactivation of M. catarrhalis OM. M. catarrhalis either in planktonic suspensions or 24-h old biofilms were exposed to aBL at the irradiance of 60 mW cm⁻². Under an aBL exposure of 216 J cm⁻², a >4-log₁₀ colony-forming units (CFU) reduction in planktonic suspensions and a >3-log₁₀ CFU reduction in biofilms were observed. Both transmission electron microscopy and scanning electron microscopy revealed aBL-induced morphological damage in M. catarrhalis. Ultraperformance liquid chromatography results indicated that protoporphyrin IX and coproporphyrin were the two most abundant species of endogenous photosensitizing porphyrins. No statistically significant reduction in the viability of HaCaT cells was observed after an aBL exposure of up to 216 J cm⁻². Collectively, our results suggest that aBL is potentially an effective and safe alternative therapy for OM caused by M. catarrhalis. Further in vivo studies are warranted before this optical approach can be moved to the clinics.     

Kinetic studies of OH reactions with Iso-propyl,Iso-butyl,Sec-butyl,and Tert-butyl acetate

The temperature dependence of the rate coefficients for the OH radical reactions with iso-propyl acetate (k₁), iso-butyl acetate (k₂), sec-butyl acetate (k₃), and tert-butyl acetate (k₄) have been determined over the temperature range 253–372 K. The Arrhenius expressions obtained are: k₁=(0.30±0.03)×10⁻¹² exp[(770±52)/T]; k₂=(109±0.14)×10⁻¹² exp[(534±79)/T]; k₃=(0.73±0.08)×10⁻¹² exp[(640±62)/T]; and k₄=(22.2±0.34)×10⁻¹² exp[−(395±92)/T] (in units of cm³ molecule⁻¹ s⁻¹). At room temperature, the rate constants obtained (in units of 10⁻¹² cm³ molecule⁻¹ s⁻¹) were as follows: iso-propyl acetate (3.77±0.29); iso-butyl acetate (6.33±0.52); sec-butyl acetate (6.04±0.58); and tert-butyl acetate (0.56±0.05). Our results are compared with the previous determinations and discussed in terms of structure-activity relationships. © 1997 John Wiley & Sons, Inc. Int J Chem Kinet: 29: 683–688, 1997.     

The near-infrared photochemistry of porphine imbedded in an N-hexane matrix

The near-infrared induced tautomerization of free-base porphine incorporated in a n-hexane-d₁₄ matrix is reported. Nernst glower irradiation on the NH stretch fundamental does not induce tautomerization, but irradiation in the regions 4000 < ν < 5100 cm⁻¹ and 5630 < ν < 7700 cm⁻¹ does induce tautomerization. Narrowband (8 cm⁻¹ fwhm) laser irradiation studies in the NH symmetric plus antisymmetric stretch combination band region (6300 < ν < 6600 cm⁻¹) show that the near-infrared induced tautomerization occurs at select wavelengths. Tautomer conversion in absence of site conversion is strong evidence that the observed photochemistry is due to porphine absorption and not hexane absorption. The estimated quantum yield of 3×10⁻⁵ for 6530 cm⁻¹ irradiation is at least one order of magnitude larger than the quantum yield expected from RRKM theory.     

The Dewar Isomer of 1,2‐Dihydro‐1,2‐azaborinines: Isolation,Fragmentation, and Energy Storage

The photochemistry of 1,2‐dihydro‐1,2‐azaborinine derivatives was studied under matrix isolation conditions and in solution. Photoisomerization occurs exclusively to the Dewar valence isomers upon irradiation with UV light (>280 nm) with high quantum yield (46 %). Further photolysis with UV light (254 nm) results in the formation of cyclobutadiene and an iminoborane derivative. The thermal electrocyclic ring‐opening reaction of the Dewar valence isomer back to the 1,2‐dihydro‐1‐tert‐butyldimethylsilyl‐2‐mesityl‐1,2‐azaborinine has an activation barrier of (27.0±1.2) kcal mol⁻¹. In the presence of the Wilkinson catalyst, the ring opening occurs rapidly and exothermically (ΔH=(−48±1) kcal mol⁻¹) at room temperature.     

Rate constants for the gas-phase reaction of ozone with 1, 1-disubstituted alkenes

The gas-phase reaction of ozone with eight alkenes including six 1,1-disubstituted alkenes has been investigated at ambient T (285–298 K) and p = 1 atm. of air. The reaction rate constants are, in units of 10⁻¹⁸ cm³ molecule⁻¹ s⁻¹, 9.50 ± 1.23 for 3-methyl-1-butane, 13.1. ± 1.8 for 2-methyl-1-pentene, 11.3 ± 3.2 for 2-methyl-1,3-butadiene (isoprene), 7.75 ± 1.08 for 2,3,3-trimethyl-1-butene, 3.02 ± 0.52 for 3-methyl-2-isopropyl-1-butene, 3.98 ± 0.43 for 3,4-diethyl-2-hexene, 1.39 ± 17 for 2,4,4-trimethyl-2-pentene, and >370 for (cis + trans)-3,4-dimethyl-3-hexene. For isoprene, results from this study and earlier literature data are consistent with: k (cm³ molecule⁻¹ s⁻¹) = 5.59 (+ 3.51, &minus 2.16) × 10⁻¹⁵ e^{(−3606±279/RT)}, n = 28, and R = 0.930. The reactivity of the other alkenes, six of which have not been studied before, is discussed in terms of alkyl substituent inductive and steric effects. For alkenes (except 1,1-disubstituted alkenes) that bear H, CH₃, and C₂H₅ substituents, reactivity towards ozone is related to the alkene ionization potential: In k<(10⁻¹⁸ cm³ molecule⁻¹ s⁻¹) = (32.89 ± 1.84) − (3.09 ± 0.20) IP (eV), n = 12, and R = 0.979. This relationship overpredicts the reactivity of C_≥3 1-alkenes, of 1,1-disubstituted alkenes, and of alkenes with bulky substituents, for which reactivity towards ozone is lower due to substituent steric effects. The atmospheric persistence of the alkenes studied is briefly discussed. © 1996 John Wiley & Sons, Inc.     

Synthesis and characterization of poly(1-benzoylsemicarbazide) and poly(1,3,4-oxadiazole amine) from 2-(p-aminophenyl)-1,3,4-oxadizolin-5-one via ring-opening

A novel thermally stable and semiconducting polyheterocycle, poly(1,3,4-oxadiazole amine), was synthesized from 2-(p-aminophenyl)-1,3,4-oxadiazolin-5-one via ring-opening. The polymer is a new class of ordered alternating copoly(aniline) containing 1,3,4-oxadiazole heterocyclic units. The polymer is highly thermally stable and exhibits no weight loss up to 370°C in air. Its electric conductivity is less than 10⁻¹⁰ S · cm⁻¹ at ambient temperature, but markedly increases to 6,5 · 10⁻⁷ S · cm⁻¹ upon doping with iodine.     

Kinetics of the reaction of OH radicals with a series of esters under simulated conditions at 295 K

The rate constants of the isopropyl acetate, n-propyl acetate, isopropenyl acetate, n-propenyl acetate, n-butyl acetate, and ethyl butyrate reactions with OH radicals were determined in purified air under atmospheric conditions, at 750 torr and (295 ± 2) K. A relative rate experimental method was used; n-heptane, n-octane, and n-nonane were the reference compounds, with, respectively, rate constants for the reaction with OH of 7.12 × 10⁻¹², 8.42 × 10⁻¹², and 9.70 × 10⁻¹² molecule⁻¹ cm³s⁻¹. The following rate constants were obtained in units of 10⁻¹² molecule⁻¹ cm³s⁻¹; isopropyl acetate, (3.12 ± 0.29); n-propyl acetate, (1.97 ± 0.24); isopropenyl acetate, (62.53 ± 1.24); n-propenyl acetate, (24.57 ± 0.24); n-butyl acetate, (3.29 ± 0.35); and ethyl butyrate, (4.37 ± 0.42). Tertiary butyl acetate has a low reactivity with OH radicals (<1 × 10⁻¹² molecule⁻¹ cm³s⁻¹). © 1996 John Wiley & Sons, Inc.     

Vibrational vave-packet dynamics in CV670 investigated by broadband femtosecond TR-CARS spectroscopy

Broadband femtosecond time-resolved coherent anti-Stokes Raman scattering ((TR-CARS)) is utilized to investigate the wave-packet dynamics of Cresyl Violet (CV670) dye molecules in ethanol solvent at room temperature. An interesting behavior of wave-packet dynamics phenomena is observed and discussed for the first time, and several unknown Raman vibrational modes with frequency differences of 32 cm⁻¹, 38 cm⁻¹, 45 cm⁻¹, 50 cm⁻¹, 55 cm⁻¹, 65 cm⁻¹, 80 cm⁻¹, 95 cm⁻¹ and 101 cm⁻¹ are excited and obtained at the same time. This work makes possible high efficiency in the structure investigation as well as dynamics of intra-molecular processes by broadband femtosecond (TR-CARS) spectroscopy with fast Fourier transformation (FFT) analysis means.     

Ambiguity in Assignment of Near Infrared Vibrational Bands for Polymerisation Monitoring of Epoxy System

The curing process of epoxy affects the chemical structure of the final network so mechanical and physical properties of the polymeric matrix for a composite may be modified according to the polymerisation conditions. This paper describes the ambiguity in assignment of reference bands to follow the cure of poly-epoxy reactive systems using a laboratory-made system which allows the coupling of dielectric analysis and Fourier Transform Near Infrared Spectroscopy (FTNIR). The dielectric measurements were obtained using interdigitated electrode. In situ monitoring of extent of reaction was carried out from room temperature up to 160 °C using fibre-optic FTNIR spectroscopy. For the DGEBA/MCDEA system the epoxy band at 6060 cm⁻¹ was chosen in preference to the band at 4530 cm⁻¹ as representative of the epoxy function evolution during polymerisation because a small unknown peak probably due to the hardener appears in the 4530 cm⁻¹ region. The bands at 4620 and 4680 cm⁻¹ assigned to aromatic combination bands and widely used as reference bands are not unique for this formulation hence the band at 5980 cm⁻¹ is used as reference. The Principal Components Analysis (PCA) shows clearly also that the bands at 4620 and 4680 cm⁻¹ vary during the polymerisation. Surprisingly, the band at 4530 cm⁻¹ is equivalent to the one at 6060 cm⁻¹ to calculate the conversion rate. It is probably due to the fact that the hardener band near 4530 cm⁻¹ follows the same behaviour as the epoxy band at 4530 cm⁻¹.