Importance of biofuels Essays

Importance of biofuels Essays Importance of biofuels Essay Importance of biofuels Essay Abstraction World demand for energy has been projected to duplicate by 2050 and be more than three-base hit by the terminal of the century. Since industrial revolution in the 1850s, the human ingestion of fossil fuels has been one of the turning causes of international concern and malaise among some industrial states. The grounds for which can be attributed to the quickly consuming militias of fossil fuels. Over the past few decennaries, with the successes achieved in familial technology engineering, progresss made in the field of biofuels offer the lone immediate solution to fossil fuels. Soon, most of the ethyl alcohol in usage is produced either from amylum or sugar, but these beginnings have non proven to be sufficient to run into the turning planetary fuel demands. However, transition of abundant and renewable cellulosic biomass into alternate beginnings of energy seems to be an effectual and promising solution. But for this engineering to go feasible there is a demand to develop inexpensive and sustainable beginnings of cellulases along with extinguishing the demand for pretreatment procedures. The reappraisal therefore aims to supply a brief overview about the demand and importance of biofuels peculiarly bioethanol with regard to the turning environmental concerns along with an pressing demand to turn to the bing jobs about cost-optimisation and big scale production of biofuels. 1.0 Introduction Biofuels are liquid fuels derived from workss. Currently, first coevals biofuels are extensively being produced and used. These are generated utilizing amylum, sugar, veggie oils and animate being fats utilizing reasonably expensive conventional engineering. In recent old ages, the fact that production of ethyl alcohol from cellulosic and lignocellulosic stuff is being hindered due to inadequate engineering to enable efficient and economically feasible methods to interrupt down the multipolymeric natural stuff has gained broad popularity ( Vermaet Al, 2010 ) . Therefore, there is a demand to develop efficient systems for the production of cellulases and other cellulose degrading enzymes. Lignocellulosic biofuels are therefore likely to be seen as a portion of the portfolio of solutions being offered to cut down high energy monetary values, including more efficient energy usage along with the usage of other alternate fuels ( Coyle, 2007 ) . 1.1 Importance of biofuels: Factors like the finite crude oil militias and invariably lifting demands for energy by the industrialised every bit good as the extremely populated states ( on their Manner to industrialization ) like India and Chinas have made it perfectly necessary to look into surrogate and efficient methods to replace these fuels in future ( Stephanopoulos, 2008 ) . Besides, concerns like steep rise in fossil fuel monetary values in the recent old ages, increasing concerns about clime alteration like planetary heating, insecurity and unrest among authoritiess due to their consuming natural militias are merely a few factors that define an pressing demand for a sustainable way towards renewable fuel engineering development ( Stephanopoulos, 2008 ) . Among the assorted types of alternate fuels considered ( liquid fuels from coal and/or biomass with and without C gaining control and storage ( CCS ) ) , biofuels derived from lignocellulosic biomass offer the most clean and sustainable option to fossi l fuels basically because of their cost fight as opposed to the current expensive methods of ethanol production from sugar cane and maize ( Stephanopoulos, 2008 ) ( Shen and Gnanakaran, 2009 ) . The planetary production and usage of biofuels has increased enormously in recent old ages, from 18.2 billion liters in 2000 to about 60.6 billion liters in 2007. It has been estimated that approximately 85 % of this sum is bioethanol ( Coyle, 2007 ) . This addition is chiefly a consequence of the grounds stated above along with lifting concerns about planetary heating and nursery gas emanations due to inordinate dodo fuels usage since biofuels are carbon-neutral and cut down green house emanations ( Sainz, 2009 ) . Besides, one of the factors lending to the viability of biofuels as an alternate transit fuel is their easiness of compatibility with our bing liquid fuel substructure ( Sainz, 2009 ) . An of import measure in the production of biofuels is the dislocation of cellulose fibers by the enzymes capable of degrading it. But the production of these enzymes is still an expensive undertaking due to their production in big micro-organism bioreactors. One method for the cheap production of these enzymes is the usage of transgenic workss as heterologic protein production systems ( Danna, 2001 ; Kusnadiet Al. , 1997 ; Twymanet Al. , 2003 ) . Plant based enzyme production offers advantages over the traditional bacterial and fungous civilizations by being commercially feasible and peculiarly attractive since in workss, the coveted protein can be made to roll up at high degrees i.e. at even greater degrees than 10 % of entire soluble protein ( Greyet Al, 2008 ) . Another major economic advantage of plant-based protein production over one that is microorganism-based is in the scale-up of protein look. Whereas scale-up of microbic systems implies big purchase and care costs for big fermentors and related equipment, scale-up of plant-based protein merchandise would merely necessitate planting of more seeds and harvest home of a larger country ( Grayet Al, 2008 ) . Cellulase showing transgenic workss may therefore offer important capital cost nest eggs over more traditional cellulase production via cellulolytic Fungis or bacteriums ( Greyet Al, 2008 ) . Ethanol is an intoxicant fuel presently made from the sugars found in grains, such as maize, sorghum, and wheat, every bit good as murphy teguments, rice, sugar cane, sugar Beta vulgariss, molasses and yard cuttings. Presently, there are two methods employed for the production of bioethanol. In the first procedure, sugar harvests or amylum are grown and fermented to bring forth ethyl alcohol. The 2nd procedure, of course oil bring forthing workss like Jatropha and algae are utilised to bring forth oils which can straight be utilised as fuel for Diesel engines after heating them to cut down their viscousness. However, presently, it is majorly being produced from amylum ( Corn in US ) and sugar ( Sugarcane in Brazil ) beginnings. Harmonizing to the latest statistics ( in 2008 ) , USA and Brazil ( fig. 1 ) were the major manufacturers of fuel ethyl alcohol by bring forthing 51.9 % and 37.3 % of planetary bioethanol severally ( hypertext transfer protocol: //www.ethanolrfa.org/industry/statistics/ # E ) . Brazil particularly produces ethyl alcohol to a big extent from agitation of sugar cane sugar to provide to one-fourth of its land transit demands ( Sticklen, 2008 ) .Similarly, to run into portion of its ain demands ; United States produces ethyl alcohol from maize. Unfortunately, inspite of being breakthrough developments, the production of ethyl alcohol by this method is non cost-efficient and hardly manages to run into less than approximately 15 % of the state s demands ( Sticklen, 2008 ) . Their usage as energy harvests is therefore presenting to be inappropriate since these are primar y nutrient beginnings, and are unstable from the point of views of long-run supply and cost ( Sainz, 2009 ) . The limitations on available land and the lifting monetary value force per unit areas would shortly restrict the production of grain and maize based ethyl alcohol to less than 8 % in the US conveyance fuel mix ( Tyner, 2008 ) . Similarly, in malice of a predicted addition to 79.5 billion liters by 2022 in ethanol production from sugar cane in Brazil, this engineering would finally be limited by the same agro-economic factors impacting the grain and the maize based ethyl alcohol production ( Sainz, 2009 ) . For e.g. the usage of maize for production of ethyl alcohol has led to an addition in the monetary values of farm animal and domestic fowl since it is the chief amylum constituent of the carnal provender. Therefore, there is an pressing demand for new and sustainable engineerings for a important part of biofuels towards the advancement of renewable beginnings of energy and the decrease of nursery gases ( Sainz, 2009 ) . Therefore, the benefits of a high efficiency of carbohydrate recovery compared to other engineerings and the possibilities of engineering betterment due to breakthrough procedures in biotechnology, offer cost-competitive solutions for bioethanol production, therefore doing the 2nd coevals or lignocellulosic beginnings the most attractive option the big scale production of biofuels ( Wyman et al, 2005 ) . 3.0 Potential of cellulosic bioethanol Cellulosic ethanolis a biofuel produced from wood, grasses, or the non-edible parts of workss. It is a type of biofuel produced frombreaking down of lignocellulose, a tough structural stuff that comprises much of the mass of workss and provides them rigidness and structural stableness ( Coyle, 2007 ) . Lignocellulose is composed chiefly of cellulose, hemicellulose and lignin ( Carroll and Sommerville, 2009 ) . Another factor that makes the production of cellulosic bioethanol a promising measure in future is that unlike maize and sugar cane, its production is non dependent on any feedcrop since cellulose is the universe s most widely available biological stuff that can be obtained from widely available low-value stuffs like wood waste, widely turning grasses and harvest wastes and manures ( Coyle, 2007 ) . But production of ethyl alcohol from lignocellulose requires a greater sum of processing to do the sugar monomers available to the micro-organisms that are typically used to bring forth ethyl alcohol by agitation. Bioethanol is one fuel that is expected to be in great planetary demand in the coming old ages since its merely chief demand is the abundant supply of biomass either straight from workss or from works derived stuffs including carnal manures. It is besides a clean fuel as it produces fewer air-borne pollutants than crude oil, has a low toxicity and is readily biodegradable. Furthermore, the usage of cellulosic biomass allows bioethanol production in states with climes that are unsuitable for harvests such as sugar cane or maize. For illustration, the usage of rice straw for the production of ethyl alcohol is an attractive end given that it comprises 50 % of the word s agronomic biomass ( Sticklen, 2008 ) . Though cellulosic ethyl alcohol is a assuring fuel from an environmental point of position, its industrial production and commercialization has non been come oning successfully. This can chiefly be attributed to the high cost of production of cellulose degrading enzymes -Cellulases ( Lyndet.al, 1996 ) . Yet another really of import factor is the pretreatment of lignocellulosic content in the biomass to let cellulases and hemicellulases to perforate and interrupt the cellulose in the cell wall. These two stairss together incur really high costs and are a hinderance in efficient production of cellulosic bioethanol. Thus works familial technology is the best alternate to bioreactors for an cheap production of these enzymes ( cellulases and hemicellulases ) . It can besides be used to modify the lignin content/amount to cut down the demand for expensive pretreatment ( Sticklen, 2008 ) . 4.0 The copiousness and construction of cellulose Photosynthetic beings such as workss, algae and some bacteriums produce more than 100 million metric tons of organic affair each twelvemonth from the arrested development of C dioxide. One-half of this biomass is made up of the biopolymer cellulose which, as a consequence, is possibly the most abundant It is the most common organic compound on Earth. Cellulose comprises about 33 per centum of all works affair, 90 per centum of cotton is composed of cellulose and so is around 50 per centum of wood ( Britannica encyclopaedia, 2008 ) . Higher works tissues such as trees, cotton, flax, sugar Beta vulgaris residues, ramee, cereal straw, etc represent the chief beginnings of cellulose. This saccharide supermolecule is the chief structural component of the cell wall of the bulk of workss. Cellulose is besides a major constituent of wood every bit good as cotton and other fabric fibers such as linen, hemp and jute. Cellulose and its derived functions are one of the chief stuffs of usage for industrial development ( paper, nitrocellulose, cellulose ethanoate, methyl cellulose, carboxymethyl cellulose ( CMC ) etc. ) and they represent a considerable economic investing ( P A ; eacute ; rez and Mackie, 2001 ) . Cellulose and lignin are the major combustible constituents of non-food energy harvests. Some of the illustrations of non-feed industrial harvests are baccy, miscanthus, industrial hemp, Populus ( poplar ) species and Salix ( willow ) . Celluloseserves as one of the major opposition to external chemical, mechanical, or biological disturbances in workss. This opposition ofcelluloseto depolymerization is offered by its happening as extremely crystalline polymer fibres ( Shen and Gnanakaran, 2009 ) .it occur in workss in two crystalline signifiers, I-aand I- A ; szlig ; ( Nishiyama et al, 2002 ) ( Nishiyama et al, 2003 ) . The crystal constructions of both these signifiers suggest that H ( H ) bonding plays a cardinal function in finding the belongingss ofcellulose ( Shen and Gnanakaran, 2009 ) .Thechemical expression of cellulose is ( C 6 H 10 O 5 ) n. It is a polysaccharide consisting of a additive concatenation of several hundred to over 10s thousand amp ; szlig ; ( 1? 4 ) linkedD- glucose unit ( Crawford, 1981 ) ( Updegraff, 1969 ) . This tough crystalline construction of cellulose molecules is turn outing to be a critical barrier in the production of cellulosic bioethanol as it is hard to breakdown the microfibr ils of crystalline cellulose to glucose ( Shen and Gnanakaran, 2009 ) . 4.1 Primary construction of cellulose The chief signifier of cellulose found in higher workss is I- A ; szlig ; . The primary construction of cellulose as shown in figure 2, is a additive homopolymer of glucose residues holding theDconfiguration and connected by A ; szlig ; ( 1-4 ) glycosidic linkages ( Sun et al, 2009 ) . Basically, the happening of intrachain and interchain H bonds ( fig. 3 ) in cellulose constructions has been known to supply thermostability to its crystal composite ( Nishiyama, 2002 ) . Intrachain H bonds are known to raise the strength and stiffness of each polymer while the interchain bonds along with weak Wander-Waal s forces hold the two sheets together to supply a 2-D construction. This agreement makes the intrachain bonding stronger than that keeping the two sheets together ( Nishiyama, 2002 ) . The concatenation length and the grade of polymerization of glucose units determine many belongingss of the cellulose molecule like its rigidness and unsolvability compared to starch ( Shigeru et al, 2006 ) . Cellulose from different beginnings besides varies in concatenation lengths, for e.g. cellulose from wood mush has lengths between 300 and 1700 units while that from fiber workss and bacterial beginnings have concatenation lengths changing from 800 to 10,000 units ( Klemm et al, 2005 ) . Cellulose, a glucose polymer is the most abundant constituent in the cell wall. These cellulose molecules consist of long ironss of sugar molecules. The procedure of interrupting down these long ironss to liberate the sugar is called hydrolysis. This is so followed by agitation to bring forth bioethanol. Assorted enzymes are involved in the complex procedure of interrupting down glycosidic linkages in cellulose ( Vermaet Al, 2010 ) . These are together known as glycoside hydrolases and include endo- acting cellulases and exo-acting cellulases or cellobiohydrolase along with A ; szlig ; -glucosidase ( Ziegelhoffer, 2001 ) ( Ziegler, 2000 ) . In the cellulose hydrolysis procedure, endoglucanase foremost indiscriminately cleaves different parts of crystalline cellulose bring forthing concatenation terminals. Exoglucanase so attaches to the concatenation terminals and cleaves off the cellobiose units. The exoglucanase besides acts on parts of formless cellulose with open concatenation terminals without the demand for anterior endoglucanase activity. Finally A ; szlig ;-glucosidase breaks the bonds between the two glucose sugars of cellobiose to bring forth monomers of glucose ( Warren, 1996 ) . Soon, two methods are widely used for cellulose debasement on an industrial graduated table: Chemical hydrolysis: This is a traditional method in which, cellulose is broken down by the action of an acid, dilute and concentrated both acids can be used by changing the temperature and the pH consequently. The merchandise produced from this hydrolysis is so neutralised and fermented to bring forth ethyl alcohol. These methods are non really attractive due to the coevals of toxic agitation inhibitors. Enzymatic hydrolysis:Due to the production of harmful byproducts by chemical hydrolysis, the enzymatic method to breakdown cellulose into glucose monomers is mostly preferable. This allows interrupting down lignocellulosic stuff at comparatively milder conditions ( 50? C and pH5 ) , which leads to effectual cellulose dislocation. 6.0 Stairss involved in cellulosic ethyl alcohol ( bioethanol ) production procedure The first measure in the production of bioethanol, involves reaping lignocellulose from the feedstock harvests, compression and eventually its transit to a mill for ethyl alcohol production where it is stored in a ready signifier for transition. The 2nd measure is the remotion of lignin nowadays in the feedstock biomass by utilizing heat or chemical pre-treatment methods. This measure facilitates the dislocation of cell wall into intermediates and removes lignin so as to let cellulose to be exposed to cellulases, which so break down cellulose into sugar residues. Presently, cellulases are being produced as a combination of bacterial and fungous enzymes for such commercial intents ( Sticklen, 2008 ) . This is so followed by stairss like detoxification, neutralization and separation into solid and liquid constituents ( Sticklen, 2008 ) . The hydrolysis of these constituents so takes topographic point by the enzymes like cellulases and hemicellulases that are produced from microorganisms in the bioreactors ( Sticklen, 2008 ) .and eventually ; ethanol is produced by sugar agitation. The figure below ( fig. 4 ) depicts the chief stairss in the production of bioethanol: 7.0 Major cell wall constituents and the cardinal enzymes involved in their dislocation 6.1 Cellulose and cellulases:About 180 billion metric tons of cellulose is produced per twelvemonth by workss globally ( Festucciet Al, 2007 ) . In the primary and secondary cell walls, about 15-30 % and 40 % dry mass severally is made up of cellulose ( Sticklen, 2008 ) . Till day of the month, it is the lone polyose being used for commercial production of cellulosic ethyl alcohol because of the commercial handiness of its deconstructing enzymes ( Sticklen, 2008 ) . As described above, three types of cellulases are involved in the dislocation of cellulose into sugars viz. , endoglucanases, exoglucanasees and A ; szlig ; glucosidase ( Ziegler, 2000 ) . 6.2 Hemicellulose and Xylanases:xyloglucans and hemicelluloses surround the cellulose microfibrils. So in order to interrupt cellulose units, specific enzymes are foremost required to first take the hemicellulose polyose. Hemicelluloses are diverse and formless and its chief component is A ; szlig ;-1, 4-xylan. Therefore, xylanases re the most bundant type of hemicellulases required to split the endo-and exo-activity ( Warren, 1996 ) . These are chiefly obtained from the FungiTrichoderma reesei,along with a big figure of bacteriums, barm and other Fungi which have been reported to produce1.4 A ; szlig ;-D xylanases. 6.3 Lignin and Laccasses:The major component of workss secondary cell wall is lignin. It accounts for about 10-25 % of entire works dry affair ( Sticklen, 2008 ) . Unlike cellulose and hemicelluloses, the lignin polymer is non peculiarly additive and alternatively comprises of a composite of phenylpropanoid units which are linked in a 3-D web to cellulose and xylose with ester, phenyl and covalent bonds ( Carpita, 2002 ) . White putrefaction Fungi ( clairvoyance.Phanerochaete chrysosporiumandTrametes versicolour) are thought degrade lignin more expeditiously and quickly than any other studied micro-organisms ( DSouza, 1999 ) .P. Chrysosporiumgreen goodss laccases like ligninases or lignin peroxidase, which initiate the procedure of debasement of lignin and manganese dependant peroxidises ( Cullen, 1992 ) . 8.0 Production of cellulases and hemicellulases in baccy chloroplasts Protein technology methodological analysiss provide the best reply to concerns sing production of improved cellulases with decreased allosteric hinderance, improved tolerance to high temperatures and specific pH optima along with higher specific activity ( Sainz, 2009 ) . The tabular array below ( table 1 ) lists different type of cellulases and hemicellulases that have been expressed in works chloroplasts: Chloroplasts are green colored plastids that have their ain genome and are found in works cells and other eucaryotic beings like algae. The targeted look of foreign cistrons in works cell organs can be used to present coveted features in a contained and economically sustainable mode ( fig. 5 ) . It besides allows us to unite assorted other advantages like easy and efficient scalability along with being wholly free of animate being pathogens. Unlike most other methods of works familial technology, the major advantage with chloroplast transmutation is their feature of transgene containment i.e. transgenes in these plastids are non spread through pollen ( Verma and Daniell, 2007 ) . This implies that chloroplast familial transmutation is reasonably a safe one and does non present the hazard of bring forthing weedkiller immune weeds ( Ho and Cummins, 2005 ) . Chloroplast transmutation involves homologous recombination. Thisnot merely minimises the interpolation of unneeded Deoxyribonucleic acid that accompaniestransformation of the atomic genome, but besides allows precisetargeting of inserted cistrons, thereby besides avoiding theuncontrollable, unpredictable rearrangements and omissions oftransgene DNA every bit good as host genome Deoxyribonucleic acid at the site of insertionthat characterises atomic transmutation ( Nixon, 2001 ) . Another advantage of chloroplast transmutation is that foreign cistrons can be over-expressed due to the high cistron transcript figure, up to 100,000 compared with single-copy atomic cistrons ( Maliga, 2003 ) . While atomic transformants typically produce foreign protein up to 1 % TSP in transformed leaf tissue, with some exceeding transformants bring forthing protein at 5-10 % TSP, chloroplast transformants frequently accumulate foreign protein at 5-10 % TSP in transformed foliages, with exceeding transformants making every bit high as A ; gt ; 40 % TSP ( Maliga, 2003 ) . Research is needed to find the stableness of the biological activity of extracted plant-produced hydrolysis enzymes in TSP when stored under freezing conditions for different periods of clip before their usage in hydrolysis ( Sticklen, 2008 ) . Two other of import and related countries for farther research are increasing the degrees of production and the biological activity of the heterologic enzymes ( Sticklen, 2008 ) .Many cell wall deconstructing enzymes have been isolated and characterised and more demand to be investigated for happening more enzymes that can defy higher transition temperatures and a scope of United States Public Health Service during pretreatment. Serious attempts to bring forth cellulosic ethyl alcohol on an industrial graduated table are already underway. Other than the Canadian Iorgen works, no commercial cellulosic ethyl alcohol works is yet in operation or under building ( Sticklen, 2008 ) . However, research in this country is afoot and support is becom A ; # xad ; ing available around the universe for this intent, from both governmental and commercial beginnings. For test A ; # xad ; ple, British Petroleum have donated half a billion dol A ; # xad ; lars to US establishments to develop new beginnings of energy chiefly biofuel harvests ( Sticklen, 2008 ) . 10.0 Decision The fact that maize ethyl alcohol produces more green house gas emanations than gasolene and that cellulosic ethyl alcohol from non-food harvests produces less green house gas emanations than electricity or H, is one of the factors that extremely favour production of ethyl alcohol from cellulosic biomass ( Verma, 2010 ) . However, biofuel production from lignocellulosic stuffs is a challenging job because of the many-sided nature of natural stuffs and deficiency of engineering to expeditiously and economically let go of fermentable sugars from the complex multi-polymeric natural stuffs ( Verma, 2010 ) . After decennaries of research aimed at cut downing the costs of microbic cellulases, their production is still expen A ; # xad ; sive ( Sticklen and Oraby, 2005 ) . One manner of diminishing such costs is to bring forth these enzymes within harvest biomass. Although some of import progresss have been made to put the foundations for works familial technology for biofuel production, this scientific discipline is still in its babyhood ( Sticklen, 2008 ) . A general challenge is to develop efficient systems for the familial transmutation of works systems for the production of cellulose degrading enzymes. Research is peculiarly needed to concentrate on the mark A ; # xad ; ing of these enzymes to multiple subcellular locations in order to increase degrees of enzyme production and bring forth enzymes with higher biological activities ( Sticklen, 2008 ) . A immense potency exists to bring forth larger sums of these enzymes in chloroplasts, and exciting advancement has been made in footing s of the harvests for which the chloroplast can now be genetically engineered. More attempts are nevertheless needed towards the development of systems to genetically engi amp ; # xad ; neer chloroplasts of biomass harvests such as cereals and perennial grasses ( Blaschke, 2006 ) . Some of the cardinal purposes of the undertaking would be: To characterize cell wall degrading enzymes Overexpression of cellulose complementary DNA in pET30 vector systems Initiation and word picture of proteins in different conditions The usage of baccy works as agencies of bring forthing cellulases through chloroplast familial technology to at the same time addresses the most of import inquiry of switching the agricultural land from provender harvests to biofuel harvests ( like maize and sugar cane at present ) along with the cost-efficient big graduated table production of cellulose degrading enzymes.

5 Cases for Requiring a Comma Before a Sentence Tag

5 Cases for Requiring a Comma Before a Sentence Tag 5 Cases for Requiring a Comma Before a Sentence Tag 5 Cases for Requiring a Comma Before a Sentence Tag By Mark Nichol A sentence tag is a word or phrase added to the beginning or end of a statement for emphasis or to provide more information. For the following sentences, I discuss the necessity of preceding end-of-sentence tags with a comma. 1. â€Å"I shouldn’t have been surprised really.† Without a comma separating really from the rest of the sentence, the implication is that really is an adverb modifying how the writer should not have been surprised (really, as in factually, and the opposite of allegedly). However, its function is merely to emphasize the point: â€Å"I shouldn’t have been surprised, really.† 2. â€Å"I was in the other room at the time actually.† This sentence indicates that the writer was in the other room in an actual manner, rather than figuratively, but that’s not the literal meaning. The writer has been challenged about his or her location when an incident occurred, and the intent, again, is to emphasize. A comma is required before actually to signal this distinction: â€Å"I was in the other room at the time, actually.† The idea could also be conveyed with actually inserted elsewhere in the sentence (in descending order of elegance): â€Å"Actually, I was in the other room at the time† or â€Å"I was, actually, in the other room at the time† or â€Å"I was in the other room, actually, at the time.† (Note that not all adverbial tags are so flexible about location; try these variations in the first example, and you’ll see that really seems to feel right only as a concluding tag.) 3. â€Å"We did it all right.† This sentence implies that the writer is evaluating a merely competent performance. With a comma inserted before â€Å"all right,† the implication is of emphasis on the fact of the accomplishment: â€Å"We did it, all right.† 4. â€Å"They offered a free pass to boot.† Without a comma preceding â€Å"to boot† (which means â€Å"as a bonus†), the phrase appears to describe an action that is, thanks to the pass, complimentary. The comma signals that â€Å"to boot† is an appendage that idiomatically offers additional information: â€Å"They offered a free pass, to boot.† 5. â€Å"Geology has an impact on biology and vice versa.† As written, this sentence seems to equate biology and vice versa as two things geology has an impact on. But â€Å"vice versa,† meaning â€Å"the opposite,† applies to the entire sentence preceding it, so it must be set off from the sentence: â€Å"Geology has an impact on biology, and vice versa.† Want to improve your English in five minutes a day? Get a subscription and start receiving our writing tips and exercises daily! Keep learning! Browse the Punctuation category, check our popular posts, or choose a related post below:30 Synonyms for â€Å"Meeting†Ã¢â‚¬Å"As Well As† Does Not Mean â€Å"And†Supervise vs. Monitor