333,108 research outputs found
The Phospha-Bora-Wittig Reaction
No full textWe report the phospha-bora-Wittig
reaction for the direct preparation
of phosphaalkenes from aldehydes, ketones, esters, or amides. The
transient phosphaborene Mes*PB–NR2 reacts
with carbonyl compounds to form 1,2,3-phosphaboraoxetanes, analogues
of oxaphosphetane intermediates in the classical Wittig reaction.
1,2,3-Phosphaboraoxetanes undergo thermal or Lewis acid-promoted cycloreversion,
yielding phosphaalkenes. Experimental and density functional theory
studies reveal far-reaching similarities between classical and phospha-bora-Wittig
reactions
The Phospha-Bora-Wittig Reaction
No full textWe report the phospha-bora-Wittig
reaction for the direct preparation
of phosphaalkenes from aldehydes, ketones, esters, or amides. The
transient phosphaborene Mes*PB–NR2 reacts
with carbonyl compounds to form 1,2,3-phosphaboraoxetanes, analogues
of oxaphosphetane intermediates in the classical Wittig reaction.
1,2,3-Phosphaboraoxetanes undergo thermal or Lewis acid-promoted cycloreversion,
yielding phosphaalkenes. Experimental and density functional theory
studies reveal far-reaching similarities between classical and phospha-bora-Wittig
reactions
4,4-Difluoro-4-bora-3a,4a-diaza-s-indacene (BDPI)-Triphenylphosphine Nanoparticles as a Photodynamic Antibacterial Agent
No full textPhotodynamic
therapy (PDT) has aroused great interest in antimicrobial
treatment because it can take advantage of the reactive oxygen species
(ROS) generated by photosensitizers under laser irradiation to kill
bacteria efficiently without causing drug resistance. Herein, we designed
a 4,4-difluoro-4-bora-3a,4a-diaza-s-indacene (BODIPY) photosensitizer
(BDPI-TPP) with a triphenylphosphine (TPP) cation for highly efficient
PDT against bacteria. The prepared BDPI-TPP nanoparticles (BDPI-TPP
NPs) can adhere to the surface of bacteria via electrostatic
interactions between the positively charged BDPI-TPP NPs and the negatively
charged bacterial membranes. More importantly, BDPI-TPP NPs exhibit
a potent antibacterial effect with a small minimum inhibitory concentration
(MIC) of only 0.3 μg mL–1 attributing to both
the positive charges and the photodynamic activity. What is more,
BDPI-TPP NPs can also damage the preformed biofilm and effectively
promote wound healing. This work highlights the potential of designing
cationic photosensitizers as highly efficient antimicrobial agents
Letter Written by Leon P. Bora to the Bryant College Service Club Dated December 12, 1943
No full text[Transcription begins]U. S. ARMY
Sunday12 Dec 1943
Bryant College Service ClubBryant CollegeProvidence, R. I.
Dear Friends,
Thanks very much for the package and also for the very interesting letter.
There are no words to describe the wonderful work you are doing.
I wish all of you a very Merry Christmas.
Yours trulyCpr Leon P. Bora
New Address:
Cpl Leon P. Bora 31228011Btry D 540th AAA.AW. Bnc/o P. M. Newport, R. I.[Transcription ends
Synthesis of 8-substituted 4, 4-difluoro-4-bora-3a,4a-diaza-s-indacene Dyes (BODIPY)
No full text4,4-Difluoro-4-bora-3a, 4a-diaza-s-indacene (BODIPY) dyes are important in synthetic and applied chemistry. The reaction of pyrrolomethane 1 with acetyl chloride and boron trifluoride etherate in the presence of triethylamine afforded the 4,4-Difluoro-3,5,8-trimethyl-4-bora-3a, 4a-diaza-s-indacene 2a. When benzoylchloride and chloroacetyl chloride were used, phenyl 2b and chloromethyl 2c derivatives formed. The treatment of pyrrolomethane 1 with 3-(phenylthio) propanal 3 in the presence of ytterbium (III) trifluoromethanesulfonate hydrate in catalitic amount yielded the 5-(2-thiophenyl ethane)-1,9-dimethyldipyrromethane 4, which was reacted with DDQ and boron trifluoride etherate in the presence of triethylamine formed 8-(2-thiophenylethan) 4,4-difluoro3,5dimethyl- 4-bora-3a, 4a-diaza-3-indacene 5. The oxidation of 8-(thiomethyl) 4,4-difluoro-3,5dimethyl- 4-bora-3a, 4a-diaza-s-indacene 6 with m-CPBA gave methylsulfonyl product 7. Bromination of 4,4-difluoro-3,5,8-trimethyl-4-bora-3a, 4a-diaza-s-indacene 2a yielded 1,2,6,7-tetrabromo- 4,4-difluoro-3,5,8-trimethyl-4-bora-3a, 4a-diaza-s-indacene 8
Breve caracterización fonológica de la lengua bora
No full textThis work offers a quick description of the vowels and consonants of the Bora language. It also explains the linguistic and sociolinguistic criteria for the selection of graphemes in the Bora language: it highlights the importance of the written tradition for the selection of certain graphemes, such as <c> and <k> or the removal of <s> and <z>. Finally, this work discuss the presence of long vowels in the Bora language: evidence to date suggests that the Bora language has only short vowels thanks to the processes of derivation with tone in the nominal Bora lexiconEste trabajo ofrece una rápida descripción de las vocales y consonantes de la lengua bora. Así mismo, explica los criterios lingüísticosy sociolingüísticos para la selección de los grafemas de la lengua bora: pone en evidencia la importancia de la tradición escrita para la selección de determinados grafemas, como <c> y <k> o la eliminación de <s> y <z>. Finalmente, se discute la presencia de las vocales largas en la lengua bora: la evidencia que se cuenta hasta la fecha sugiera que la lengua bora posee solo vocales breves gracias a los procesos de derivación con el tono en el léxico nominal bora
Mesoscale characteristics of southern Adriatic bora storms
No full textThe bora in Dalmatia is compared to the better known bora in the northern Adriatic. Fifteen severe storms in Split are selected during the period January 1980 to January 1983.
It is shown that in most cases such a severe bora does not last long, but the gusts are above 30 m s-1, with the absolute maximum of 45 m s-1, and therefore it is comparable with the strength of northern Adriatic bora. The mean surface pressure distribution and AT 500 hPa for these cases emphasize a mesoscale cyclone in the southern Adriatic, which may or may not be seen on large scale (synoptic) charts. Two “bora types” according to local weather characteristics are distinguished. “Dark bora” (cyclonic type) with cloudy sky and precipitation is characterized by deeper surface cyclone and a pronounced upper-level trough from Baltic to the southern Adriatic, in contrast to cloudiness (anticyclonic) “clear bora” when mesoscale cyclone is further to the east of Adriatic. The upper level flow in latter case shows a cut-off low with N-NE current above the bora throughout the troposphere. These patterns are in agreement with Defant’s (1951) description of cyclone and anticyclone bora types; they stress both upstream and downstream influence and emphasize the interaction of large-, meso- and local-scale processes on the Dalmatian bora flow.
The ALPEX bora case of 11-15 March 1982 illustrates local differences in bora occurrence and strength along the Adriatic, and the time cross sections exhibit the characteristics of upstream vertical atmospheric structure for bora onset and decay
Cold air outbreak and the Adriatic bora
No full textThe case studies of two cold air outbreaks in Zagreb which cause a local wind bora on the eastern Adriatic area are presented ( 17 December 1978 and 7 January 1982 ).
The cold air outbreak on 17 December 1978 appeared as a shallow zone of large equivalent potential temperature drop ( Q e ) and NE wind with maximum at 800 m above ground. The stable layer which was placed above this zone was more expressed in terms of vertical Q e - rather than temperature-structure which was consequence of very humid and warm air advected from SW above the cold bora layer. This upstream bora layer characteristics and strengthening of cyclonic activity on the Tyrrhenian Sea caused a longlasting and strong bora associated with precipitation on the northern Adriatic . The strongest bora with maximum gusts of 35.2 m s -1 and with the longest duration of bora was 28-40 hours with the maximum gusts varying from 14.9 m s -1 to 34.7 m s -1 .
In the case of 7 January 1982 , a strong bora, associated with anticyclone strengthening over the middle Europe , occurred along the entire Adriatic coast as a consequence of an expressed cold and dry air outbreak. The main characteristic in this situation was a narrow zone of sudden drop of Q e and NE wind with a maximum at 2.5 km altitude. The stability above this zone was smaller than in the first situation and the temperature fall occurred throughout the troposphere. Due to extremely dry air supply, the bora occurred without precipitation lasting from 16 to 31 hours and even 52 hours in Senj. The maximum gusts varied from 17.0 m s -1 to 35.4 m s -1 .
Two case studies are not enough for a general conclusion but it should be emphasized that the bora had quite different characteristics in the considered frontal situations
Erratum to: Search for heavy Higgs bosons decaying to a top quark pair in proton-proton collisions at s√ = 13 TeV
No full textIn figure 7 of the original publication, the label of the y axis should have been (Formula presented.)”. The corrected version is shown in figure 1. Accordingly, the text pointing to the figure should read “figure 7 shows scans of (Formula presented.) for this hypothesis, as a function of the coupling modifier gAtt-”. © The Author(s).Publisher versio
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