Mechanical and Bioactive Properties of PMMA Bone Cement: A Review.

Over the past few decades, poly(methyl methacrylate) (PMMA) based bone cement has been clinically used extensively in orthopedics for arthroplasty and kyphoplasty, due to its biocompatibility and excellent primary fixation to the host bone. In this focused review, we discuss the use of various fillers and secondary chemical moieties to improve the bioactivity and the physicochemical properties. The viscosity of the PMMA blend formulations and working time are crucial to achieving intimate contact with the osseous tissue, which is highly sensitive to organic or inorganic fillers.

Chemical composition of cloud and rainwater at a high-altitude mountain site in western India: source apportionment and potential factors.

This study focuses on the chemical composition of cloud water (CW) and rainwater (RW) collected at Sinhagad, a high-altitude station (1450 m AMSL) located in the western region of India. The samples were collected during the monsoon over two years (2016-2017). The chemical analysis suggests that the concentration of total ionic constituents was three times higher in CW than in RW, except for NH (1.

Ligand-Controlled Copper-Catalyzed Halo-Halodifluoromethylation of Alkenes and Alkynes Using Fluorinated Carboxylic Anhydrides.

Polyhalogenated molecules are often found as bioactive compounds in nature and are used as synthetic building blocks. Fluoroalkyl compounds hold promise for the development of novel pharmaceuticals and agrochemicals, as the introduction of fluoroalkyl groups is known to improve lipophilicity, membrane permeability, and metabolic stability. Three-component 1,2-halo-halodifluoromethylation reactions of alkenes are useful for their synthesis.

Compensatory effect of biomass burning on black carbon concentrations during COVID-19 lockdown at a high-altitude station in SW India.

The characteristics of black carbon (BC) aerosols, their sources, and their impact on atmospheric radiative forcing were extensively studied during the COVID-19 lockdown (28th March-31st May 2020) at a high-altitude rural site over the Western Ghats in southwest India. BC concentration and the contribution of BC originating from biomass burning (BC) estimated from the aethalometer model during the lockdown period were compared with the same periods in 2017 and 2018 and with the pre-lockdown period (1st February to March 20, 2020). BC concentrations were 44, 19, and 17% lower during the lockdown period compared with the pre-lockdown periods of 2020 and similar periods (28th March to 31st May) of 2017 and 2018, respectively.

Bengali Migrant Workers in South India: A Mixed-Method Inquiry into Their Earnings, Livings and Struggle During Covid Pandemic.

This study has tried to compare the earning and non-earning aspects of migrant workers from West Bengal engaged in different types of work in Karnataka and Kerala based on survey of 111 Bengali-speaking migrant workers and a number of in-depth interviews and FGDs. The study has found that most of the migrant workers landed in south India only after working in Kolkata, northern or western Indian cities. Lack of regular employment opportunities and low-wage rate in rural as well as urban West Bengal are the dominant reasons for their migration.

NHC-Catalyzed Desymmetrization of N-Aryl Maleimides Leading to the Atroposelective Synthesis of N-Aryl Succinimides.

Although the construction of axially chiral C-C bonds leading to the atroposelective synthesis of biaryls and allied compounds are well-known, the related synthesis of compounds bearing axially chiral C-N bonds are relatively rare. Described herein is the N-heterocyclic carbene-catalyzed atroposelective synthesis of N-aryl succinimides having an axially chiral C-N bond via the desymmetrization of N-aryl maleimides. The NHC involved intermolecular Stetter-aldol cascade of dialdehydes with prochiral N-aryl maleimides followed by oxidation afforded N-aryl succinimides in good yields and ee values.

Seasonal characteristics of boundary layer over a high-altitude rural site in Western India: implications on dispersal of particulate matter.

The temporal variability of the planetary boundary layer height (PBLH) over Mahabaleshwar was studied for a period of 1 year from 1 December 2015 to 30 November 2016 using microwave radiometer (MWR) observations. The PBLH over Mahabaleshwar was found to be the highest during the pre-monsoon (March-May) season and lowest during the winter (December-February) season. The seasonal mean of PBLH was estimated to be 339±88 m during winter, 485±70 m during pre-monsoon, 99±153 m during monsoon, and 438±24 m during post-monsoon season.

Recent advances in reactions using diacyl peroxides as sources of O- and C-functional groups.

Diacyl peroxides, (RCO2)2, are readily available and widely used reagents for organic synthesis, because they can serve as electrophiles, oxidants, and radical sources. Recently, they have been used extensively as sources of O- and C-functional groups, in contrast to their classical applications as radical initiators. These novel reaction modes have greatly expanded the synthetic utility of diacyl peroxides by making it possible to simultaneously utilize plural functionalities of diacyl peroxides in unprecedented ways, with or without the aid of transition-metal catalysts.

Enantioselective Synthesis of Tricyclic β-Lactones by NHC-Catalyzed Desymmetrization of Cyclic 1,3-Diketones.

The NHC-catalyzed desymmetrization of cyclic-1,3-diketones allowing the enantioselective construction of tricyclic β-lactones with five contiguous stereocenters, including two quaternary stereocenters, has been developed. The mild and operationally simple addition of α-bromoenals to cyclopentane-1,3-diketone derivatives proceeds via the initial formation of chiral α,β-unsaturated acylazolium intermediates and culminates in a cascade reaction, following the Michael-aldol-lactonization pathway to deliver the β-lactone derivatives in moderate to good yields and excellent selectivity.

Sub micron aerosol variability and its ageing process at a high altitude site in India: Impact of meteorological conditions.

The effect of relative humidity and temperature on the submicron aerosol variability and its ageing process was studied over a high altitude site, Mahabaleshwar in south-west India. The mass composition of non-refractory particulate matter of 1 μm (NR-PM) size was obtained using Time of Flight Aerosol Chemical Speciation Monitor (ToF-ACSM) along with the measurements on a few trace gases during winter (December 2017-February 2018) and summer season (20th March - 5th May 2018). Sulfate exhibited strong dependence on the relative humidity (RH) as its mass fraction increased with the increase in RH.

N-Heterocyclic Carbene-Catalyzed Formal [6+2] Annulation Reaction via Cross-Conjugated Aza-Trienolate Intermediates.

The diverse reactivity of N-heterocyclic carbenes (NHCs) in organocatalysis is due to the possibility of different modes of action. Although NHC-bound enolates and dienolates are known, the related NHC-bound cross-conjugated aza-trienolates remain elusive. Herein, we demonstrate the NHC-catalyzed formal [6+2] annulation of nitrogen-containing heterocyclic aldehydes with α,α,α-trifluoroacetophenones leading to the formation of versatile pyrrolooxazolones (29 examples).

Navigation Algorithm Based on the Boundary Line of Tillage Soil Combined with Guided Filtering and Improved Anti-Noise Morphology.

An improved anti-noise morphology vision navigation algorithm is proposed for intelligent tractor tillage in a complex agricultural field environment. At first, the two key steps of guided filtering and improved anti-noise morphology navigation line extraction were addressed in detail. Then, the experiments were carried out in order to verify the effectiveness and advancement of the presented algorithm.

NHC-Catalyzed Generation of α,β-Unsaturated Acylazoliums for the Enantioselective Synthesis of Heterocycles and Carbocycles.

This Account is aimed at highlighting the recent developments in the N-heterocyclic carbene (NHC)-catalyzed generation of α,β-unsaturated acylazolium intermediates and their subsequent reactivity with (bis)nucleophiles thereby shedding light on the power of this NHC-bound intermediate in organocatalysis. This key intermediate can be generated by the addition of NHCs to α,β-unsaturated aldehyde or acid derivatives. A wide variety of bisnucleophiles can add across the α,β-unsaturated acylazoliums to form various five and six-membered heterocycles and carbocycles.

Black carbon: source apportionment and its implications on CCN activity over a rural region in Western Ghats, India.

This study presents the characteristics of black carbon aerosol (BC) over a high-altitude site, Mahabaleshwar during the monsoon season. The mass concentration of BC exhibits a morning peak and a daytime build-up with a mean mass concentration of 303 ± 142 ng m. The simultaneous measurements of aerosol particle number concentration (PNC), cloud condensation nuclei concentration (CCN), and non-refractory particulate matter less than 1 μm size (NR-PM) were also made by using a Wide-Range Aerosol Spectrometer (WRAS), CCN counter and Aerosol Chemical Speciation Monitor (ACSM) respectively.

Synthesis of 2-Aryl Naphthoquinones by the Cross-Dehydrogenative Coupling Involving an NHC-Catalyzed endo-Stetter Reaction.

An N-heterocyclic carbene (NHC)-catalyzed intramolecular Stetter reaction proceeding via the endo-fashion was the key step for the transition-metal-free and mild cross-dehydrogenative coupling of 2-cinnamoyl benzaldehydes allowing for the synthesis of 2-aryl naphthoquinones. In this transformation, the carbene generated from the triazolium salt using NaCO catalyzes the intramolecular Stetter reaction, which was followed by air oxidation to reinstall the C-C double bond.

Enantioselective N-Heterocyclic Carbene-Catalyzed Cascade Reaction for the Synthesis of Pyrroloquinolines via N-H Functionalization of Indoles.

Functionalization of the indole N-H bond for enantioselective synthesis of biologically important pyrroloquinoline derivatives has been reported under oxidative N-heterocyclic carbene catalysis conditions. The interception of catalytically generated chiral α,β-unsaturated acylazoliums with the indole derivatives proceeds in an aza-Michael/Michael/lactonization sequence to deliver the pyrroloquinoline derivatives in good yields, diastereoselectivities, and enantioselectivities. The simultaneous enhancement of reactivity and selectivity observed in polar aprotic solvents is noteworthy.

N-Heterocyclic Carbene-Catalyzed Enantioselective Synthesis of Spiro-glutarimides via α,β-Unsaturated Acylazoliums.

NHC-catalyzed enantioselective [3 + 3] spiro-annulation of α,β-unsaturated aldehydes with cyclic β-ketoamides allowing the preparation of synthetically and biologically important spiro-glutarimide derivatives has been reported. The interception of the ketoamides with catalytically generated chiral α,β-unsaturated acylazoliums proceeds in a Michael addition-intramolecular amidation pathway to deliver the spirocyclic products with good yield, diastereoselectivity, and enantioselectivity.

Recent Advances in the Organocatalytic Enantioselective Synthesis of Functionalized β-Lactones.

This Focus Review highlights recent developments in the organocatalytic enantioselective synthesis of β-lactone derivatives. Owing to the importance of β-lactones as a heterocyclic motif that is present in a variety of natural products and biologically active molecules, several catalytic methods have been developed for the synthesis of these compounds in their enantiomerically pure form. Organocatalytic methods that employ N-heterocyclic carbenes (NHCs), cinchona alkaloids, isothioureas, 4-dimethylaminopyridine (DMAP) derivatives, and phosphines have allowed the highly enantioselective synthesis of β-lactones from cheap and readily available starting materials.

N-Heterocyclic Carbene-Catalyzed Michael-Michael-Lactonization Cascade for the Enantioselective Synthesis of Tricyclic δ-Lactones.

Enantioselective synthesis of tricyclic δ-lactones with three contiguous stereocenters has been demonstrated by the N-heterocyclic carbene (NHC)-catalyzed functionalization of benzylic C(sp)-H bonds. The NHC-catalyzed reaction of enals with dinitrotoluene derivatives under oxidative conditions proceeds via the chiral α,β-unsaturated acylazoliums and produces the δ-lactones in good yields and excellent diastereoselectivity and enantioselectivity. This mild and atom-economic cascade reaction takes place in a Michael/Michael/lactonization sequence and tolerates a broad range of functional groups.

Can Short-term Economic Policies Hurt the Health of the Poor? Demonetization in India.

In November 2016, the Government of India (GOI) demonetized the commonly used Rs500 and Rs1,000 denominations. This was a short-term economic policy, known as notebandi, implemented as a means to address black money, counterfeit currencies, and terrorist activities. Notebandi was unrolled in a chaotic, confusing, and complex manner, leaving many people with limited access to cash in their daily activities.

Enantioselective Synthesis of Functionalized β-Lactones by NHC-Catalyzed Aldol Lactonization of Ketoacids.

N-Heterocyclic carbene (NHC)-catalyzed intramolecular aldol lactonization of readily available ketoacids leading to the enantioselective synthesis of cyclopentane-fused β-lactones is presented. The reaction proceeds via the generation of NHC-bound enolate intermediates formed from the ketoacids in the presence of the peptide coupling reagent HATU and NHC generated from the chiral triazolium salt. The functionalized β-lactones are formed under mild conditions in high yields and enantioselectivities.

Organocatalytic Enantioselective Vinylogous Michael-Aldol Cascade for the Synthesis of Spirocyclic Compounds.

Enantioselective synthesis of pyrazolone-fused spirocyclohexenols by the secondary amine-catalyzed cascade reaction of α,β-unsaturated aldehydes with α-arylidene pyrazolinones is reported. This formal [3 + 3] organocascade reaction proceeds through a vinylogous Michael-aldol sequence to furnish the spiroheterocycles with three stereocenters including an all-carbon quaternary center in good yields and selectivities. The catalytic generation of α,β-unsaturated iminium ions from enals and tandem dienolate/enolate formation from pyrazolinones are the key for the success of this spiroannulation reaction.

Enantioselective synthesis of spiro γ-butyrolactones by N-heterocyclic carbene (NHC)-catalyzed formal [3 + 2] annulation of enals with 3-hydroxy oxindoles.

The N-heterocyclic carbene (NHC)-catalyzed enantioselective formal [3 + 2] annulation of α,β-unsaturated aldehydes with 3-hydroxy oxindoles is presented. Under oxidative conditions using the bisquinone oxidant, the reaction resulted in the synthesis of spiro γ-butyrolactones in moderate to good yields, enantioselectivity and diastereoselectivity. The reaction likely proceeds via the generation of the NHC-bound α,β-unsaturated acylazolium intermediate from enals, which was intercepted by the dioxindoles in a formal [3 + 2] pathway to form the spirocyclic compounds.

N-Heterocyclic-Carbene-Catalyzed Umpolung of Imines.

N-Heterocyclic carbene (NHC) catalysis has been widely used for the umpolung of aldehydes, and recently for the umpolung of Michael acceptors. Described herein is the umpolung of aldimines catalyzed by NHCs, and the reaction likely proceeds via aza-Breslow intermediates. The NHC-catalyzed intramolecular cyclization of aldimines bearing a Michael acceptor resulted in the formation of biologically important 2-(hetero)aryl indole 3-acetic-acid derivatives in moderate to good yields.

Enantioselective Synthesis of Spirocyclohexadienones by NHC-Catalyzed Formal [3+3] Annulation Reaction of Enals.

The enantioselective synthesis of pyrazolone-fused spirocyclohexadienones was demonstrated by the reaction of α,β-unsaturated aldehydes with α-arylidene pyrazolinones under oxidative N-heterocyclic carbene (NHC)catalysis. This atom-economic and formal [3+3] annulation reaction proceeds through a vinylogous Michael addition/spiroannulation/dehydrogenation cascade to afford spirocyclic compounds with an all-carbon quaternary stereocenter in moderate to good yields and excellent ee values. Key to the success of the reaction is the cooperative NHC-catalyzed generation of chiral α,β-unsaturated acyl azoliums from enals, and base-mediated tandem generation of dienolate/enolate intermediates from pyrazolinones.