Fabrication of Unique Mixed-Valent CoICoII and CuICuII Metal-Organic Frameworks (MOFs) for Desulfurization of Fuels: A Combined Experimental and Theoretical Approach toward Green Fuel.

Herein, metal-organic framework (MOF)-based adsorbents are designed with distinct hard and soft metal building units, namely, [Co2ICoII(PD)2(BP)] (Co_PD-BP) and [Cu2ICuII(PD)2(BP)] (Cu_PD-BP), where H2PD = pyrazine-1,4-diide-2,3-dicarboxylic acid and BP = 4,4'-bipyridine. The designed MOFs were characterized via spectral and SCXRD techniques, which confirm the mixed-valent states (+1 and +2) of the metal ions. Topological analysis revealed the rare ths and gwg topologies for Co MOF, while Cu-MOF exhibits a unique 8T21 topology in the 8-c net (point symbol for net: {424·64}). Moreover, severe environmental issues can be resolved by effectively removing heterocyclic organosulfur compounds from fuels via adsorptive desulfurization. Further, the developed MOFs were investigated for sulfur removal via adsorptive desulfurization from a model fuel consisting of dibenzothiophene (DBT), benzothiophene (BT), and thiophene (T) in the liquid phase using n-octane as a solvent. The findings revealed that Cu_PD-BP effectively removes the DBT with a removal efficiency of 86% at 300 ppm and an operating temperature of 25 °C, with a recyclability of up to four cycles. The adsorption kinetic analysis showed that the pseudo-first-order model could fit better with the experimental data indicating the physisorption process. Further, the studies revealed that adsorption capacity increased with the increasing initial DBT concentration with a remarkable capacity of 70.5 mg/g, and the adsorption process was well described by the Langmuir isotherm. The plausible reason behind the enhanced removal efficiency shown by Cu_PD-BP as compared to Co_PD-BP could be the soft-soft interactions between soft sulfur and soft Cu metal centers. Interestingly, density functional theory (DFT) studies were done in order to predict the mechanism of binding of thiophenic compounds with Cu_PD-BP, which further ascertained that along with other interactions, the S···π and S···Cu interactions predominate, resulting in a high uptake of DBT as compared to others. In essence, Cu_PD-BP turns out to be a promising adsorbent in the field of fuel desulfurization for the benefit of mankind.

Synthesis of 2D Metal-Organic Nanosheets (MONs) by Liquid Phase Exfoliation: Applications in Effective Delivery of Antiulcer Drugs and Selective Adsorption and Removal of Cationic Dyes.

Nowadays, the fabrication of 2D metal-organic nanosheets (2D MONs) has entered the research arena fascinating researchers worldwide. However, a lack of efficient and facile methods has remained a bottleneck for the manufacturing of these 2D MONs. Herein, a 2D metal-organic framework (MOF), i.e., 2D Cu-MOF, was synthesized using a facile and convenient stirring method by using 4,4'-trimethylenedipyridine (TMDP) as an organic linker. The as-prepared MOF was characterized in detail and based on single crystal X-ray diffraction analysis, it was established that tangled layers in the 2D Cu-MOF are interconnected to produce thick strands. These tangled layers could be easily separated via ultrasonication-induced liquid phase exfoliation (UILPE) to give the 2D Cu-MON as illustrated through Tyndall light scattering and exhaustive microscopic exploration such as scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The application of this 2D Cu-MON was assessed in the field of drug delivery revealing exceptional drug loading for the drug lansoprazole (LPZ) by 2D Cu-MONs as well as drug release in the acidic and neutral medium demonstrating that the 2D Cu-MON is an excellent carrier for antiulcer drug delivery. For environmental protection, the application of 2D Cu-MON was also examined toward the removal of various cationic and anionic dyes with excellent selectivity toward cationic dye removal. The plausible mechanism for dye removal indicated the involvement of cation-π and π-π interactions, for the effective adsorption of cationic dyes as well as a increase in the surface area of 2D Cu-MON by UILPE. Remarkably, the high drug loading and dye removal are imputed to the increase in surface area by UILPE. In a nutshell, the developed 2D Cu-MON will prove to be beneficial for application in the field of drug delivery as well as for wastewater treatment.

Structure, DFT studies and evaluation of catechol oxidase (CO) mimic activity of mononuclear Co(II) complexes derived from aminoalcohols: an experimental and theoretical approach.

The impetus to modeling of enzyme mimics comes from their potential to provide insight to the alternate mechanistic pathways of the native enzymes. The present study demonstrates the syntheses and characterization of two different cobalt(II) complexes, [Co(pdm)(Phen)Cl]Cl·H2O (1) and [Co(pmmH)2(SCN)2] (2) with the aminoalcohol ligands such as pyridine-2,6-dimethanol (pdmH2) or 2-pyridinemonomethanol (pmmH) and their assessment as catechol oxidase (CO) enzyme mimic. Single Crystal X-ray diffraction and powder X-ray diffraction data suggest the octahedral environment around the Co(II) ion and the complexes form extensive 1D or 2D propagating network as a result of non-covalent interactions (O···H and C-H···π). TD-DFT calculations were used to explain the spectral bands obtained during the UV-Vis absorption studies and it is ascertained that the transitions were mainly of the intra-ligand charge transfer (ILCT) type. The catecholase biomimetic catalytic activity of the synthesized complexes has been investigated in detail and the kinetics is also performed. The results obtained show that both the complexes catalyze the aerobic oxidation of catechol to the corresponding o-quinone. The Kcat value for 1 is 106.99 h‒1 and for 2 is 90.32 h‒1 in methanol. It may be mentioned here that 1 and 2 are effective catalysts, with the order of activity being 1 > 2. The order of enzymatic activity is well justified by CV and DFT studies.Communicated by Ramaswamy H. Sarma.

Novel {Cu4} and {Cu4Cd6} clusters derived from flexible aminoalcohols: synthesis, characterization, crystal structures, and evaluation of anticancer properties.

Two new copper clusters, {Cu4} and {Cu4Cd6}, with polydentate aminoalcohol ligands, diethanol propanolamine (H3L1) and bis-tris{2-[bis(2-hydroxyethyl)amino]-2-(hydroxymethyl)propane-1,3-diol} (H6L2), have been synthesized under mild conditions and characterized thoroughly by single-crystal X-ray diffraction (XRD), infrared spectroscopy, elemental analysis, powder XRD, magnetic and DFT studies, and absorption and fluorescence spectroscopy. The cluster {Cu4} exhibits a rare tetranuclear copper cubane core whereas {Cu4Cd6} forms an unusual heterometallic cage owing to the introduction of the second metal Cd into the ligand. A hexapodal ligand (H6L2) with N and O donor atoms was chosen deliberately for the construction of a high-nuclearity cluster, i.e., {Cu4Cd6}. Interestingly, both the clusters displayed significant cytotoxicity towards human cervical (HeLa) and lung (A549) cancer cells as evident from the shallow IC50 values [15.6 ± 0.8 µM (HeLa), 18.5 ± 1.9 µM (A549) for {Cu4}, and 11.1 ± 1.5 µM (HeLa), 10.2 ± 1.3 µM (A549) for {Cu4Cd6}] obtained after a 24 h incubation. However, moderate toxicity was observed toward immortalized lung epithelial normal cells (HPL1D) with IC50 values of 32.4 ± 1.2 µM for {Cu4} and 27.6 ± 1.7 µM for {Cu4Cd6}. A cellular apoptotic study using HeLa cells revealed that the {Cu4} cluster triggered apoptosis at both the early and late phases while the {Cu4Cd6} cluster facilitate apoptosis mainly at the late apoptotic stage. A standard 2',7'-dichlorodihydrofluorescein-diacetate (DCFH-DA) test affirms that both the clusters enhanced ROS production inside the cancer cells, responsible for promoting cell apoptosis. The decanuclear {Cu4Cd6} clusters demonstrated better anticancer activity compared to the tetranuclear {Cu4} clusters, indicating the role of high nuclearity and additional Cd metal in the enhanced intracellular production of ROS.

Fabrication of gelatin/silk fibroin/phage nanofiber scaffold effective against multidrug resistant Pseudomonas aeruginosa.

OBJECTIVE: The alarming rise of multi-drug resistant (MDR) Pseudomonas aeruginosa has prompted the World Health Organization to consider it a serious threat to human health. Although phage (Phg), an effective antibacterial treatment option, can maintain long-term infectivity via lyophilized storage, freeze-drying can be expensive and time-consuming. Thus, we propose electrospun gelatin/fibroin (G/F) nanofibrous formulation for dehydrating and storing phage against MDR P. aeruginosa. SIGNIFICANCE: The formulation of phage within the nanofibrous structure of the electrospun G/F scaffold would result in antimicrobial activity against MDR P. aeruginosa leading to enhanced wound healing. METHODS: Phg effective against MDR P. aeruginosa was isolated, characterized and loaded within G/F nanofibers by electrospinning. Morphology, crystallinity and thermal stability as well as the antimicrobial activity and the biocompatibility of the developed G/F/Phg nanofibers were determined. RESULTS: Phg-loaded G/F nanofibers revealed an amorphous structure with good thermal stability at temperatures below 300 °C and exhibited effective antibacterial activity against MDR P. aeruginosa with ∼2 log reduction in the bacterial count which increased to ∼4 log reduction in bacterial count after 16 h as compared to both the G/F nanofibers and the negative control. Lack of cytotoxic effects on cultured fibroblasts supported the biocompatibility of G/F/Phg nanofibers. CONCLUSION: The developed G/F/Phg nanofibers are able to maintain the viability of phage and represent a promising antimicrobial dressing for wounds infected with MDR P. aeruginosa.

Antibacterial activity of Salvadora persica against oral pathogenic bacterial isolates.

OBJECTIVE: The objective was to determine the antibacterial activity of Salvadora persica extract against bacteria isolated from dental plaque of patients. MATERIALS AND METHODS: Out of 40 different clinical specimens collected from patients suffering from plaque-induced gingivitis, 12 Staphylococcus aureus and 8 Streptococcus sp. isolates were recovered. The isolates were screened for their biofilm-forming capacity using tissue culture plate (TCP), tube method (TM), and congo red agar (CRA) method. Antibacterial activity of methanolic S. persica extract as well as of commercial antimicrobials against tested isolates was performed. High-performance liquid chromatography-mass spectrometry (HPLC-MS) and gas chromatography-MS (GC-MS) analysis were performed for S. persica crude extract and its volatile oil, respectively, to determine their constituents. RESULTS: Out of 20 isolates, 80%, 85%, and 90% showed positive results using TM, CRA, and TCP, respectively. The highest antimicrobial activity of methanolic S. persica extract was observed at 200 mg/ml. HPLC-MS analysis shows many polyphenols in S. persica extract such as Chrysin-8-c-ß-D-glucopyranoside, ferulic acid, gallic acid, and stigmasterol. Chemical composition of the essential oil of S. persica was determined by GC-MS yield; a mixture of monoterpene and hydrocarbons. The major compounds were butylated hydroxytoluene followed by benzene (isothiocyanatomethyl). CONCLUSION: Methanolic extract of S. persica had significant antibacterial effect against S. aureus and Streptococcus sp. isolates, and it may be gave a good alternative method for controlling oral pathogen.

Modeling of the hemodynamics in the feet of patients with peripheral artery disease.

To simulate the hemodynamic effects in the feet in response to a thigh cuff occlusion, we have developed a multi-compartmental model in which the circulatory system for the leg is represented by its electrical equivalents. Dynamic vascular optical tomographic imaging data previously obtained from 20 patients with peripheral artery disease (PAD) and 20 healthy subjects is used to test the model. Analyzing the clinical data with the support of the model yields diagnostic specificity and sensitivity in the 90-95% range, significantly higher than previously reported.

Barriers to Kidney Transplantation as a Choice of Renal Replacement Therapy.

Brunei Darussalam has a live related kidney transplant program since 2013. Uptake of transplant remains poor in the country despite full government subsidy for health care. This study aims to assess barriers and factors affecting patients' preference toward dialysis over transplant as their choice of renal replacement therapy. It is hoped that the study can provide a better insight into the poor uptake of transplant in the country. METHODS: The target population was all patients with end-stage renal disease undergoing dialysis in Brunei Darussalam who are fit enough to undergo kidney transplant. The shortlisted patients were approached during their hemodialysis sessions or while waiting for clinical reviews in peritoneal dialysis clinics and were given self-administered structured questionnaires. RESULTS: Out of 348 eligible patients in the country, 226 (64.9%) agreed to participate in the study. The majority of patients (71.2%), especially the unmarried patients (81.5%), cited "lack of donor" as their main reason for not choosing transplant. "Happy with dialysis" (31.9%), "inadequate information" (21.2%), "unwilling to take risk" (26.5%), and "financial problems" (18.1%) were the other common factors identified. A total of 51.8% of the respondents had considered transplant, and 42.5 % of patients had considered the option of commercialization through foreign black market channels. Younger patients (<40 years) on dialysis for less than 5 years with higher education were more likely to consider transplant (P < .05). Likewise, patients who were younger, highly educated, and employed were more likely to choose commercialization (P < .05). CONCLUSION: Lack of donor and poor knowledge were the main barriers to patients receiving kidney transplant in the country. Religio-cultural barriers, lack of reimbursement, poor knowledge, and stringent donor criteria contributed to the limited donor pool. Despite universal health coverage for the population, financial and social security factors were still important determinants that influenced recipients' and donors' decisions to reject transplant.

Fluoroquinolones and BK Virus Nephropathy: A Myth or a Reality.

BK polyomavirus (BKV) is a challenging problem for the transplant nephrologist. Various strategies have been used to prevent or treat BK virus nephropathy (BKVN). These include reduction in immunosuppression, intravenous immune globulin, cidofovir, leflunomide, and the fluoroquinolone antibiotics. All these agents have their own toxicities. Great interest was shown to use fluoroquinolones to prevent BKVN after its useful experience was reported in bone marrow transplant. Fluoroquinolones being cheap and easily available, attracted nephrologists to use it, for prevention of BKVN. These agents have been shown in vitro studies to be effective. However, there are mixed results about their effectiveness in prevention of BKVN in clinical setting. This review will focus the evidence available for using fluoroquinolones in prevention of BKVN and its usefulness. Furthermore, a way forward to use these agents or not for prevention of BKVN will also be discussed.

Air quality in Yanbu, Saudi Arabia.

UNLABELLED: Yanbu, on the Red Sea, is an affluent Saudi Arabian industrial city of modest size. Substantial effort has been spent to balance environmental quality, especially air pollution, and industrial development. We have analyzed six years of observations of criteria pollutants O3, SO2, particles (PM2.5 and PM10) and the known ozone precursors-volatile organic compounds (VOCs) and nitrogen oxides (NOx). The results suggest frequent VOC-limited conditions in which ozone concentrations increase with decreasing NOx and with increasing VOCs when NOx is plentiful. For the remaining circumstances ozone has a complex non-linear relationship with the VOCs. The interactions between these factors at Yanbu cause measurable impacts on air pollution including the weekend effect in which ozone concentrations stay the same or even increase despite significantly lower emissions of the precursors on the weekends. Air pollution was lower during the Eids (al-Fitr and al-Adha), Ramadan and the Hajj periods. During Ramadan, there were substantial night time emissions as the cycle everyday living is almost reversed between night and day. The exceedances of air pollution standards were evaluated using criteria from the U.S. Environmental Protection Agency (EPA), World Health Organization (WHO), the Saudi Presidency of Meteorology and Environment (PME) and the Royal Commission Environmental Regulations (RCER). The latter are stricter standards set just for Yanbu and Jubail. For the fine particles (PM2.5), an analysis of the winds showed a major impact from desert dust. This effect had to be taken into account but still left many occasions when standards were exceeded. Fewer exceedances were found for SO2, and fewer still for ozone. The paper presents a comprehensive view of air quality at this isolated desert urban environment. IMPLICATIONS: Frequent VOC-limited conditions are found at Yanbu in Saudi Arabia that increase ozone pollution if NOx is are reduced. In this desert environment, increased nightlife produces the highest levels of VOCs and NOx at night rather than the day. The effects increase during Ramadan. Fine particles peak twice a day-the morning peak is caused by traffic and increases with decreasing wind, potentially representing health concerns, but the larger afternoon peak is caused by the wind, and it increases with increasing wind speeds. These features suggest that exposure to pollutants must be redefined for such an environment.

Extraction and characterization of lignin from oil palm biomass via ionic liquid dissolution and non-toxic aluminium potassium sulfate dodecahydrate precipitation processes.

The objective of this study is to extract and characterize lignin from oil palm biomass (OPB) by dissolution in 1-butyl-3-methylimidazolium chloride ([bmim][Cl]), followed by the lignin extraction through the CO2 gas purging prior to addition of aluminum potassium sulfate dodecahydrate (AlK(SO4)2 · 12H2O). The lignin yield, Y(L) (%wt.) was found to be dependent of the types of OPB observed for all precipitation methods used. The lignin recovery, RL (%wt.) obtained from CO2-AlK(SO4)2 · 12H2O precipitation was, however dependent on the types of OPB, which contradicted to that of the acidified H2SO4 and HCl solutions of pH 0.7 and 2 precipitations. Only about 54% of lignin was recovered from the OPB. The FTIR results indicate that the monodispersed lignin was successfully extracted from the OPT, OPF and OPEFB having a molecular weight (MW) of 1331, 1263 and 1473 g/mol, and degradation temperature of 215, 207.5 and 272 °C, respectively.

Detection of Peripheral Arterial Disease Within the Foot Using Vascular Optical Tomographic Imaging: A Clinical Pilot Study.

OBJECTIVE: Vascular optical tomographic imaging (VOTI) is a novel imaging modality that is capable of detecting hemoglobin concentrations in tissue. VOTI is non-invasive, non-ionizing and does not require contrast injection. This technology was applied to the diagnosis of peripheral arterial disease (PAD) within lower extremities of diabetic patients with calcified arteries. This could be of substantial benefit as these patients suffer from comorbidities such as arterial incompressibility, which complicates diagnosis and monitoring. METHODS: Forty individuals (10 non-diabetic patients with PAD, 10 diabetic patients with PAD, and 20 healthy volunteers) were enrolled in a diagnostic pilot study using the VOTI system. The patients were imaged during at high pressure cuff occlusion. RESULTS: The VOTI system was capable of quantifying the blood volume changes within the foot during the thigh cuff occlusion and outputting diagnostic parameters, such as change in hemoglobin concentration, enabling the assessment of foot perfusion. This study resulted in a statistically significant difference between the healthy cohort and both the non-diabetic and the diabetic PAD cohorts (p = .006, p = .006). Receiver operating characteristic (ROC) curve analysis showed that PAD diagnosis could be made with over 80% sensitivity or specificity depending on the characteristic cutoff point. In addition, VOTI was capable of providing the locations of under-perfused regions within the foot and evaluating the severity of arterial disease, even within diabetic patients with calcified arteries, who are traditionally difficult to diagnose. CONCLUSION: VOTI can effectively diagnose PAD independently of arterial compressibility, making it very useful for assessing vascular disease in diabetic patients.

Investigation of biofilm formation on contact eye lenses caused by methicillin resistant Staphylococcus aureus.

OBJECTIVE: The objective was to investigate the biofilm-forming capacity of methicillin resistant Staphylococcus aureus (MRSA) isolated from eye lenses of infected patients. MATERIALS AND METHODS: A total of 32 MRSA isolated from contact lenses of patients with ocular infections were screened for their biofilm-forming capacity using tube method (TM), Congo red agar (CRA), and microtiter plate (MtP) methods. The effect of some stress factor on the biofilm formation was studied. The biofilm-forming related genes, icaA, icaD and 10 microbial surface components that recognize adhesive matrix molecule (MSCRAMM), of the selected MRSA were also detected using polymerase chain reaction. RESULTS: Of 32 MRSA isolates, 34.37%, 59.37%, and 81.25% showed positive results using CRA, TM or MtP, respectively. Biofilm production was found to be reduced in the presence of ethanol or ethylenediaminetetraacetic acid and at extreme pH values. On the other hand, glucose or heparin leads to a concentration dependent increase of biofilm production by the isolates. The selected biofilm producing MRSA isolate was found to harbor the icaA, icaD and up to nine of 10 tested MSCRAMM genes, whereas the selected non biofilm producing MRSA isolate did not carry any of the tested genes. CONCLUSIONS: The MtP method was found to be the most effective phenotypic screening method for detection of biofilm formation by MRSA. Furthermore, the molecular approach should be taken into consideration for the rapid and correct diagnosis of virulent bacteria associated with contact eye lenses.

A sensitive colorimetric assay for identification of Acinetobacter baumannii using unmodified gold nanoparticles.

AIMS: Acinetobacter baumannii is a global health problem, which threatens many healthcare settings. The current study aims to develop a detection assay for Ac. baumannii using unmodified gold nanoparticles (AuNPs). METHODS AND RESULTS: Fifty-three Ac. baumannii clinical isolates were collected from Egyptian hospitals. Bacterial isolation and biochemical identification of isolates were carried out followed by DNA extraction using boiling method and PCR amplification of the 23S-16S rRNA intergenic spacer sequences (ITS). AuNPs were synthesized using citrate reduction method. Detection and optimization of Ac. baumannii amplicons using unmodified spherical AuNPs were performed using species-specific DNA oligonucleotide. The nano-gold assay was able to colorimetrically detect and distinguish Ac. baumannii from other Gram-negative bacteria. The turnaround time of the assay is about 2 h including sample treatment and amplification. The assay detection limit is 0·8125 ng of DNA. CONCLUSIONS: The developed colorimetric assay is sensitive, fast and reliable and can be used for identification of Ac. baumannii. SIGNIFICANCE AND IMPACT OF THE STUDY: There is a need to develop robust, rapid, and specific methods for detection of Ac. baumannii isolated from clinical specimens. The developed nanogold assay prototype allows sensitive, specific and rapid detection of amplified DNA of A. baumannii and represents a reliable diagnostic tool to aid routine laboratory identification of this pathogen.

Neuroblastoma stem cells - mechanisms of chemoresistance and histone deacetylase inhibitors.

Cancer stem cells (CSCs) form a small proportion of tumor cells that have stem cell properties: self-renewal capacity, the ability to develop into different lineages and proliferative potential. The interest in CSCs emerged from their expected role in initiation, progression and recurrence of many tumors. They are generally resistant to conventional chemotherapy and radiotherapy. There are two hypotheses about their origin: The first assumes that CSCs may arise from normal stem cells, and the second supposes that differentiated cells acquire the properties of CSCs. Both hypotheses are not mutually exclusive, as it is possible that CSCs have a diverse origin in different tumors. CD133+ cells (CD133 is marker of CSC in some tumors) isolated from NBL, osteosarcoma and Ewing sarcoma cell lines are resistant to cisplatin, carboplatin, etoposide and doxorubicin than the CD133- ones. Being resistant to chemotherapy, there were many attempts to target CSCs epigenetically including the use of histone deacetylase inhibitors. The diverse influence of valproic acid (histone deacetylase inhibitor) on normal and cancer stem cells was proved in different experiments. We have found an increase percentage of CD133+ NBL cells after their incubation with VPA in a dose that does not induce apoptosis. Further researches on CSCs and clinical application for their detection are necessary: (i) to define the CSC function in carcinogenesis, cancer development and their role in metastasis; (ii) to find a specific marker for CSCs in different tumors; (iii) to explain the role of different pathways that determine their behavior and (iv) to explain mechanisms of chemoresistance of CSCs.

A wireless handheld probe with spectrally constrained evolution strategies for diffuse optical imaging of tissue.

We present a low-cost, portable, wireless diffuse optical imaging device. The handheld device is fast, portable, and can be applied to a wide range of both static and dynamic imaging applications including breast cancer, functional brain imaging, and peripheral artery disease. The continuous-wave probe has four near-infrared wavelengths and uses digital detection techniques to perform measurements at 2.3 Hz. Using a multispectral evolution algorithm for chromophore reconstruction, we can measure absolute oxygenated and deoxygenated hemoglobin concentration as well as scattering in tissue. Performance of the device is demonstrated using a series of liquid phantoms comprised of Intralipid(®), ink, and dye.

Observed trends for CF3-containing compounds in background air at Cape Meares, Oregon, Point Barrow, Alaska, and Palmer Station, Antarctica.

The concentrations of CF(3)-containing compounds in archived air samples collected at Cape Meares, Oregon, from 1978 to 1997, at Point Barrow, Alaska, from 1995 to 1998, and at Palmer Station, Antarctica, from 1991 to 1997, were determined by high resolution gas chromatography and high resolution mass spectrometry. The CF(3)-containing compounds measured by this method and discussed here are: the perfluorinated compound, C(3)F(8) (FC 218); four perhalogenated compounds, CF(3)Cl (CFC 13), CF(3)CF(2)Cl (CFC 115), CF(3)CFCl(2) (CFC 114a), and CF(3)Br (Halon 1301); and three hydrofluorocompounds, CF(3)H (HFC 23), CF(3)CH(3) (HFC 143a), and CF(3)CH(2)F (HFC 134a). For four of these compounds, very few measurements have been previously reported. The atmospheric concentrations of all of the CF(3)-containing compounds continuously increased in time over the sample collection periods. From these data, the annual rates of emission into the atmosphere have been estimated. The emission rates fall into one of three distinct categories. The annual emission rates of C(3)F(8), CF(3)H, CF(3)CH(3), and CF(3)CH(2)F have continuously increased over the last two decades. That of CF(3)CFCl(2) has decreased continuously. Emission rates for CF(3)Cl, CF(3)CF(2)Cl, and CF(3)Br reached maximum levels in the late 1980s, and have been decreasing in the 1990s. The emission rates of C(3)F(8), CF(3)CH(3) and CF(3)CH(2)F were nearly zero 20 years ago but have increased rapidly during the last decade.

A new model of tropospheric hydroxyl radical concentrations.

A chemistry model of the global troposphere is presented which focuses on the hydroxyl radical, OH. Global distributions of OH are calculated based on known chemical reaction pathways, experimentally measured values of precursor species O3, H2O, NOx (defined as NO+NO2), CO, CH4, and actinic flux (which includes the effects of cloud cover and O3 column absorption). Model grid resolution is 1 km in altitude by 10 degrees latitude, and zonally divided into land or ocean. Species are calculated as seasonal averages. Global annual mean OH in the troposphere (up to 14 km altitude) is calculated to be 9.2 x 10(5) molcm(-3) with averages of 9.8 x 10(5) in the northern hemisphere, and 8.5 x 10(5) in the southern hemisphere. Global CO and CH(4) oxidation rates by OH are calculated to be 1840 Tgyear(-1) and 580 Tgyear(-1), respectively. OH is found to be most sensitive to O3 and H2O concentrations, as well as to the photolysis rate of O3 to O1D. Sensitivity of CO and CH4 oxidation rates to cloud presence shows an inverse relationship to cloud amount and optical depth. Model results are shown to be consistent with results from two other published models.

Characterization of non-methane hydrocarbons emitted from various cookstoves used in China.

Emission contributions from cookstoves to indoor, regional, and global air pollution largely depend on stove and fuel types. This paper presents a database on emission factors of speciated non-methane hydrocarbons (NMHCs) for 16 fuel/stove combinations burning 2 types of crop residue, wood, 4 types of coal, kerosene, and 3 types of gaseous fuels. The emission factors are presented both on a fuel mass basis (compound mass per fuel mass) and on a cooking task basis (compound mass per unit energy delivered to the pot). These fuel/stove combinations cover a large spectrum of the cookstoves used in both urban and rural households in China. Up to 54 hydrocarbons were identified, some of which are reactive precursors of photochemical smog. Based on published maximum incremental reactivity (MIR) values for NMHCs, we estimated stove-specific and fuel-specific ozone forming potentials (OFPs). The results indicate that raw coal powder, wood, and crop residues have higher OFP values than the other types of fuels tested. Strikingly, burning the coal briquette and honeycomb coal briquette produced OFP values more than 2 orders of magnitude lower than burning unprocessed (raw) coal, even in the same vented metal stove, for every 1 MJ delivered to the pot.

Thioglycolic acid and pyrazole derivatives of 4(3H)-quinazolinone: synthesis and antimicrobial evaluation.

New derivatives of 4(3H)-quinazolinone were synthesized and evaluated for their antibacterial and antifungal activity. The derivatives are: 3-Aryl-2-[3-aryl-1-(carboxymethylthio)-3-oxopropyl)]-4(3H)-quinazolinones 2a-f; 3-Aryl-2-(3-aryl-1H-pyrazol-5-yl)-4(3H)-quinazolinones 3a-f; 3-Aryl-2-(1,3-diaryl-1H-pyrazol-5-yl)-4(3H)-quinazolinones 4a-f; 3-Aryl-2-(3-aryl-1-thiocarbamoyl-1H-pyrazol-5-yl)-4(3H)-quinazolinones 5a-f; 3-Aryl-2-[3-aryl-1-(carboxymethylthio)-3-hydroxyiminopropyl)]-4(3H)- quinazolinones 6a-f; and 3-Aryl-2-[3-aryl-1-(carboxymethy- lthio)-3-thiocarbamoyliminopropyl)]-4(3H)-quinazolinones 7a-f. Some of the tested compounds showed activity comparable to that of the standard references used.