Carrier tests to assess microbicidal activities of chemical disinfectants for use on medical devices and environmental surfaces

For well over a decade, many deficiencies have been identified in current AOAC methods used to assess the microbicidal activities of chemical disinfectants on medical devices and environmental surfaces. This report discusses the development of quantitative carrier tests (QCT) designed to address these concerns. Decontamination of surfaces with dried inocula is invariably more difficult than when microorganisms are in suspension. For medical device as well as environmental decontamination, microbicides are used on contaminated surfaces, thus making it necessary to evaluate their microbicidal action on representative carrier materials contaminated with a dried challenge microorganism(s). Our approach is a 2-tiered QCT. The first tier (QCT-1) uses relatively ideal conditions to assess performance of the microbicide for screening purposes; the test uses smooth glass surfaces and quantities of disinfectant in excess of those likely to be experienced in the field. The second tier of testing (QCT-2) is more stringent because it uses (1) disks of brushed stainless steel as carriers, (2) only 50 microL of the test formulation on each carrier as compared to 1 mL in QCT-1, and (3) an added soil load to simulate the presence of residual body fluids or accumulated surface dirt. This review also discusses the factors that affect disinfection of medical devices and environmental surfaces in the context of the methodology used to evaluate the potency of microbicides. Specific recommendations for discussion are included, and performance criteria are suggested based on a risk-reduction approach for different classes of disinfectants. The focus is on improving the relevance of the test methodology to actual field use of disinfectants for devices and facilities in health care, and potentially in other settings. It is hoped that this review and its recommendations will initiate needed discussion and resolution of the many issues identified.     

An Exact Chameleon Cosmological Model Unifying Phantom Inflation with Late-Time Acceleration

An exact Chameleon cosmological model describing the evolution of a non-singular bouncing cosmology with the phantom divide line crossing is obtained by constructing two independent functions of the scalar field.     

Efficient One-Pot Synthesis of Polyhydroquinoline Derivatives Using Silica Sulfuric Acid as a Heterogeneous and Reusable Catalyst Under Conventional Heating and Energy-Saving Microwave Irradiation

An efficient Hantzsch four-component condensation reaction for the synthesis of polyhydroquinoline derivatives was reported under two conditions: solvent-free conventional heating and energy-saving microwave irradiation. The process is simple and environmentally benign, and the use of a heterogeneous and reusable catalyst, high yields, and short reaction times are the key features of this protocol.     

Two New Insecticidal Amides and a New Alcoholic Amide from Piper nigrum Linn.

Three new amides, pipgulzarine ( 1 ), pipzorine ( 2 ), and piptahsine ( 3 ), have been isolated from the dried seeds of Piper nigrum Linn. along with nine known constituents: (2E,4E,8Z)‐N‐(isobutyl)eicosatrienamide, pellitorine, pipercide, piperine, stigmastanol, stigmasterol, decurrenal, stigmasterol 3‐O‐β‐D ‐glucopyranoside, and 5,10(15)‐cadinen‐4‐ol. The structures of the new constituents have been established as (2E,11E)‐12‐(benzo[1,3]dioxol‐5‐yl)‐N‐(2‐methylpropyl)dodeca‐2,11‐dienamide ( 1 ), (2E,12Z)‐N‐(4‐methylpentyl)octadeca‐2,12‐dienamide ( 2 ), and (2E,4S)‐4‐hydroxy‐N‐(2‐methylpropyl)hex‐2‐enamide ( 3 ). The structures of 1 – 3 were derived by spectral studies and chemical reactions, and by comparison of spectral data in the case of known constituents. Compounds 1 and 2 , and most of the already known compounds, exhibited toxicity against fourth instar larvae of Aedes aegypti Liston. The isolated (Z) double bond in 2 was assigned on the basis of its EI‐MS fragmentation pattern and its reaction with OsO₄. The (S) configuration at C(4) of 3 was determined by Horeau's method. This is the first report of the isolation of a 4‐methylpentylamide from P. nigrum, while shorter branched amides have been reported from this genus [1].     

Spherical Symmetric Perfect Fluid Collapse in <Emphasis Type="Italic">f</Emphasis>(<Emphasis Type="Italic">R</Emphasis>, <Emphasis Type="Italic">T</Emphasis>) Gravity

This paper contains the study of spherically symmetric perfect fluid collapse in the frame work of f(R, T) modified theory of gravity. We proceed our work by considering the non-static spherically symmetric background in the interior and static spherically symmetric background in the exterior regions of the star. The junction conditions between exterior and interior regions are presented by matching the exterior and interior regions. The field equations are solved by taking the assumptions that the Ricci scalar as well as the trace of energy-momentum tensor are to be constant, for a particular f(R, T) model. By inserting the solution of the field equations in junction conditions, we evaluate the gravitational mass of the collapsing system. Also, we discuss the apparent horizons and their time formation for different possible cases. It is concluded that the term f(R ₀, T ₀) behaves as a source of repulsive force and that’s why it slowdowns the collapse of the matter.     

Isolation and structure determination of two new constituents from the fruits of Morinda citrifolia Linn

Studies on the chemical constituents of the fruits of Morinda citrifolia Linn. have led to the isolation of two new compounds, morinaphthalene (=1,3,6,7-tetrahydroxy-2-hydroxymethyl-1,2,3,4-tetrahydronaphthalene, (1); and morindafurone (=5-hydroxy-1,10b-dihydro-6H-anthra [1,9-bc] furan-6-one, (2); as well as two known constituents, 1,8-dihydroxy-6-methoxy-3-methyl-9-anthrone (3) and 2,4-dimethoxy-9-anthrone (4). Their structures were elucidated by spectral analysis including 2D NMR techniques.     

Hierarchy of susceptibility of viruses to environmental surface disinfectants: a predictor of activity against new and emerging viral pathogens

Proper disinfection is crucial to interrupt the environmental spread of many viruses. In the case of new and emerging viruses still awaiting culture and full characterization, it is proposed that any official recommendations for disinfectant use be based on the well-established hierarchy of susceptibility to such chemicals as related to virus particle size and structure.     

A simple kinetic model for oxidative coupling of methane over La_(0.6)Sr_(0.4)Co_(0.8)Fe_(0.2)O_(3-δ) nanocatalyst

A simplified kinetic model for the oxidative coupling of methane over a La0.6Sr0.4Co0.8Fe0.2O3-δ nanocatalyst is presented. The kinetic model was developed by experimental data in a catalytic micro-reactor covering a wide range of reaction conditions (0.04相似文献   

Green synthesis and biological activity investigation of new derivatives of spiroisatins

In this research, the synthesis of novel derivatives of spiroisatins in high yields was investigated. These new compounds were synthesized using a multicomponent reaction (MCR) of isatin, malononitrile, acetophenone derivatives, diethyl oxalate, primary amines, and Et₃N in aqueous media. Under similar conditions, spiropyrroloisatins were prepared using MCRs of synthesized spiroistins. The antioxidant activity of newly synthesized spiroisatins is due to having an NH group which was evaluated by two procedures. Also, the antimicrobial activity of newly generated spiroisatins was evaluated by a disk distribution process utilizing two kinds of Gram-negative bacteria and Gram-positive bacteria and bacterial growth was stopped using these compounds. The advantages of this method are short reaction times, high yields of products, and the easy separation of catalyst and product using simple procedures.