Causes of Luminescence and Chemiluminescence

Causes of Luminescence and Chemiluminescence 1.1. Luminescence Phenomena Luminescence is the phenomenon of emission of electromagnetic radiation in excess of thermal radiation. The radiation is usually in the visible region of the electromagnetic spectrum, however, since the same basic processes may yield infrared or ultra violet radiation. Luminescence is observed with all phases of matter: gases, liquids and solids both organic and inorganic[1]. Luminescence is an umbrella term for those kinds of events where light emission is not the result of high temperature. In fact with increasing temperature the competing nonradiative de – excitation processes become more probable and the intensity of the luminescent emission decreases. Luminescence in living organisms has been reported as far back as 1500 BC. In Chinese literature, the best known examples being the emission of light from fireflies and glow – worms[2, 3]. 1.1.1Types of Luminescence Classification according to the means by which energy is supplied to excite the luminescent molecule[4-8].Table 1.1 Table (1-1):- Different types of luminescence phenomena Excitation source Luminescence type Produced from irradiation Absorption of Uv-vis or near IR radiation. (Conversion of light energy to chemical energy). Photoluminescence Emission produced from irradiation of ÃŽ ² particles. Cathodoluminescence Emission produced from irradiation of ÃŽ ± particle. Anodoluminescence Radiation-induced chemical excitation (irradiation of ÃŽ ³ particles. Radiodoluminescence Produced from heating. Emission from incandescent solids Candoluminescence Caused by solid subjected to mild heating. Thermoluminescence Flame-excited metal atoms Pyroluminescence Produced from structural rearrangements in solids Emission from shaking, rubbing, or crushing crystals. Triboluminescence Emission from crystallization. Crystalloluminescence Excitation induced from dissolution of an irradiated or other energy-donating solid. Lyoluminescence Produced from electrical phenomena. Radiative recombination of electrons and holes in material (emission from electrical discharge) Electroluminescence Emission during electrolysis Galvanoluminescence Excitation of compounds by ultra-sonication. Sonoluminescence Emission from fractional charge separation at the crystal surface. Piezoluminescence Produced from chemical reactions Emission from luminous organisms. Bioluminescence Chemical excitation of compounds. Chemiluminescence 1.2. Chemiluminescence The term chemiluminescence (CL.) was first coined by Eilhardt Weidman in 1888. Chemiluminescence is defined as the production of electromagnetic radiation observed when a chemical reaction yields an electronically excited intermediate or product. CL-reactions emit light of varying degrees of intensity and lifetime. With colors that spare the visible spectrum [9-11]. Analytically, the CL-reactions are attractive due to: excellent detection limits results from the absence of source of noise and scattering, suitable to both batch and flow techniques highly sensitive, determinable over a wide range of concentrations, easy to operate, simplicity, absence of unwanted background so the only background signal is that of the PMT dark current and no excitation source or optical filters are required as compared to other optical or photo luminescence methods [12, 13]. However, some disadvantages are to be considered as well; A chemiluminescence reagent may yield significant emission not just for one unique analyte i.e. a lack of selectivity may occur. Moreover, chemiluminescence emission intensities are sensitive to a variety of environmental factors such as temperature, solvent, ionic strength, pH and other species present in the system. As a result, a separation condition (HPLC, capillary electrophoresis (CE), may not always match the optimum CL-emission conditions. Third, as the emission intensity from a CL-reaction varies with time,light flash composed of signal increase after reagent mixing, passing through a maximum, then decreasing back to the base – line, thus the CL- emission versus time profile differs from one compound to another and care has to be taken to detect the signal in the flowing stream during strictly defined periods [14].chemiluminescence technique is versatile for determination of a wide variety of species that can participate in the CL-reaction such as; CL-substrates or CL-precursors responsible for the excited state [15], the necessary reagent for the CL-reactions (usually an oxidant) [16] , some species that enhance the rate or sensitivity of the CL-reaction[17] ,activators such as catalysts (enzymes[18] or metal ions[19] CL. analysis found a wide application not only in the organic technology, medicine, food testing, but also in environmental monitoring and material science [20-24]. CL-reactions can be coupled as a detection technique [25] in chromatography [26, 27], capillary electrophoresis [28-30], or immunoassay, providing qualitative and / or quantitative information [31, 32]. 1.2.1. Mechanisms of Chemiluminescence Reaction Figure (1-2) shows the types of the CL-reaction mechanisms. In general CL-reactions can be generated by two basis mechanisms: Figure (1-2):- Types of CL-reactions. P, product; F, fluorescing substance Direct CL-reactions: a substrate (A) and an oxidant (B) in the presence of cofactors react to form an intermediate product in an electronically excited state which relaxes to the ground state with a photon emission. The catalyst is an enzyme or metal ions, reduces the activation energy and provides an adequate environment for producing high CL-efficiency out of the process.Cofactors sometimes are necessary to convert one or more of the substrates into a form capable of reacting and interacting with the catalyst,or to provide an efficient leaving group if bond cleavage is required to produce the excited emitter [33]. An alternative for compounds producing ultra-weak CL-emission is: Indirect or sensitized CL reactions: Since not all excited states of CL-reactions products are effective â€Å"emitters† in any case, thus the excited state energy can be transferred to an â€Å" effective â€Å" flourophore added to the system, in –order to increase the CL-intensity substantially . The most salient asset of chemical excitation is the low background noise involved, which results in very low detection limits (in the sub femtomole of region) [34,35]. Enhanced CL- reactions (ECL): describes the phenomenon which has been observed in a wide range of chemi and bioluminescence reactions. Enhancement of light emission from the luminol-hydrogen peroxide reaction at alkaline pH has been achieved by the addition of various organic compounds generally containing oxonium group. Enhancement of CL. Reaction led to intense light emission, prolonged light emission and low background[36]. Spontaneous light emission during reaction requires the presence of the following conditions[37]: The reaction must be highly exothermic (40-70 kcal/mole) in order that the CL-reaction occurred in the visible region (400 nm (violet) – 750nm (red). These exothermic conditions associated with redox reactions using Oxygen, Ozone andhydrogen peroxide or similar potential oxidants. The reaction pathway must be a favorable to channel the energy for the formation of an electronically excited state. Photon emission must be favorable deactivation process of the excited product in relation to other competitive non-radiative processes that may appear in low proportion. There are several ways for an electronically excited state species to lose its extra energy, either by reacting with another molecule, molecular dissociation, and collision with its surrounding molecules or luminescence. In the latter case it can react to liberate sufficient energy to produce photon of visible light, figure (1-3). Figure (1-3):-possible de-excitation pathways of excited molecule 1.2.2. Main Chemiluminescence-systems for analytical processes 1.2.2.1. Gas- phase chemiluminescence reactions. The development of Chemiluminescence Methods for determining components of a gas is largely originated from the need to determine atmospheric pollutants such as Ozone, Oxides of nitrogen and sulfur compounds[45, 46].The best known and most frequently used is the reaction of nitrogen oxide withOzone.CL-NOXanalyzers have been shown to respond to a number of nitrogenous pollutants besides NO and NO2. [40].Some analytical methods based on CL- reactions have been proposed for the determination of sulfur monoxide and unsaturated hydrocarbons such as Alkenes, alkynes and aromatics at high temperature,several of these are as follows[41-44]. NO+ O3NO2* + O2NO2 + hÃŽ ½(600-2800 nm)(1) (2) (3) Oxygen atoms also been applied as strong oxidants when reacted with a wide range of analyst, although not so frequently used. The reaction with nitric oxide produces a yellow- green CL-emission that has been used for measuring concentration of Oxygen atoms in kinetics experiments[45]. (4) Some CL. Reactions are based on the light emission produced in flame, rather than the cold CL-emission. Molecular emission cavity analysis (MECA) is a CL-technique in which molecular emission are generated within a cavity that is introduced into a hydrogen diffusion flame. This flame acts as the environments of radicals, atoms and molecules which promote the chemical reactions (i.e. high temperature of flame promote of chemical reactions that form key reaction intermediates and provide additional thermal excitation of the emitting species).The cavity acts as the environment for stabilizing the emitting species. MECA has been used for selective detection of compounds containing sulfur, nitrogen, phosphorous, antimony, arsenic,.Tin and halogens [46-54]. 1.2.2.2. Liquid- phase chemiluminescence reactions There are some well – established CL-reagents that have been used for solution – phase CL-reactions, their attraction include high sensitivity, wide dynamic range and simplicity [55].The Chemiluminescence of luminal and the cyclic hydrazides of aromatic and heterocyclic acids is one of the classical and still studied in CL-reactions [56]. Although hydrazides in general are Chemiluminescent, onlyhydrazides related to luminol (5 – aminophthalyhydrazide) can be considered the most commonly used. The CL. of luminol was first described by Albrecht in 1928. This compound reacts with potent oxidizing agents in the presence of catalyst in alkaline medium to yield 3 – amino phthalate in an excited electronic state which returned to the ground state; with the production ofblue emission at 425 nm.The reaction is catalyzed by metal ions.Alternatively, it has been proposed that the metal ion forms a complex with the hydrazide which is then oxidized[57–59]. Lophin(2,4,5 – triphenylimidazole) is the most representative of the imidazole CL-precursors . A yellow CL-emission is produced at 525 nm. by oxidation of Luphin in aqueous alkaline mediums[60]. Lucigenine(10, 10 dimethyl – 9, 9 -biascridiniumnitrate) is one of the most efficient CL-substances which emit an intense green emission at 470 nm. When oxidized in an alkaline medium [61]. In relation to indirect CL., one of the more efficient non – biological system that are used is based on and so – called peroxy oxalate CL-reaction (PO – CL ) which involves the hydrogen peroxide oxidation of an aryl oxalate ester in the presence of a fluorophore .Bis–( 2,4,6 – trichloro phenyl )oxalate (TCPO) and bis – ( 2,4– dinitro phenyl ) oxalate (DNPO ) are commonly used oxalates. These compounds are insoluble in water which requires the use of organic solvents such as acetonitrilies ,dioxane and ethyl acetate [62]. Another CL-system frequently applied involves the use of Ru [bpy]3+2 which produces an orange emission at 610 nm.From the excited state (Ru [bpy]3+2)* that can be obtained by different reactions which imply electron transfer and regeneration of Ru[bpy ]3+2 species. Recently , the higher CL-emission generated by a similar complex , Ru[phen]3+2(phen = 1,10 – phenanthroline) during oxidation ofRu [bpy ]3+2 by Ce(IV) in sulfuric acid medium Ru [bpy]3+2 is the most studied as an inorganic compound used in electro generated CL (ECL)[60,63]. 1.2.2.3.Solid Phase Chemiluminescence [35]. Some polymers exhibit weak CL. in the visible range when heated up in the presence of inert gas (air or oxygen). For the first time this phenomenon was observed by Ashby in 1961, from polypropylene. Emission of light during oxidation of polymers is called oxy- luminescence or oxychemiluminescence. And for CL. of polymers to be observed, oxygen must be present in the process. 1.2.3.Electro Generated Chemiluminescence (ECL) ECL : is the process in accordance with which , species generated at electrodes undergo high – energy electron – transfer reactions to form excited states that emit light , it occurs in the visible region of spectrum as a consequence of fast and highly exo-energetic electron . Transfer between a strong electron donor and electronacceptor which in turn results in generation of excited states [7].In general, electrically generated reactants diffuse from one or more electrodes, and undergo high – energy electron transfer reactions either with one other or with chemicals in solution. This process yields excited state molecules, which produce a CL- emission in the vicinity of the electrode surface. Application of ECL have almost exclusively focused on the reaction of tris(2, 2 – bipyridire) ruthenium Ru[bpy]3+2 the reaction takes place at room temperature . Wide pH range and in the presence of oxygen and many other impurities[64].Ru [bpy]3+2 itself can undergo electron transfer reactions to produce ECL as follows [65]. Luminol can undergo an ECL reaction due to its versatility in analytical determinations. in alkaline solution luminol anion undergoes a single electron electro-oxidation to form diazaquinine , which is further oxidized by peroxide or super oxide to give 3 – amino phthalate in an excited state , which emits light at 425 nm . Luminol ECL has been used for determination of species such as phenyl alanine, ibuprofen and hisidine [9]. 1.3. Fluorescence Photoluminescence becomes visible as optical radiation accompanied by the emission of photon depending on the duration of the phenomenon, i.e. life time of the excited state. Fluorescence is the spontaneous emission of light during transition of the system from its lowest vibrational energy level of an excited singlet state S1 back to the ground state S0,thus it’s a spin allowed process. Absorption and fluorescence don’t require any spin reorientation however; intersystem crossing and phosphorescence require a spin reorientation therefore; absorbance and fluorescence are much faster than phosphorescence. The processes that occur between the absorption and emission of light are usually illustrated by Jobalonski diagram [66, 67]; figure (1-4). Figure (1-4):- Perrin- Jobalonski diagram and illustration of the relative positions of absorption (Abs), fluorescence (F), andphosphorescence (Ph.) Fluorescence is the result of three stages process that occurs in certain molecules called fluorophores [67]. Excitation: a photon is supplied by an external source and absorbed by the fluorophore creating an excited electronic singlet state S1. This stage distinguishes fluorescence from chemiluminescence, in which the excited state is populated by a chemical reaction. State life time:fluorescence life time is typically 1-10 Nano sec. during this time the fluorophore undergoes conformational changes and is also subjected to a multitude of possible interactions with its molecular environment such as collisional quenching and intersystem crossing. Fluorescence emission: when a photon of energy is emitted returning the fluorophore to the ground stat S0. Figure (1-5) shows these three stages. Figure (1-5):- three stages of fluorescence emission process 1.3.1. Characteristics of fluorescence emission [68-70] Emission spectra are typically independent of the excitation wave length due to the partial dissipation of excitation energy during the excited state life time, this known as Kasha’s rule. The emission intensity is proportional to the amplitude of the fluorescence excitation spectrum at the excitation wavelength; figure (1-6). Figure (1-6):- emission spectra are typically independent of the excitation wavelength Stokes shift: due to the energy dissipation during the excited state life time, the energy of this photon is lower and therefore; of longer wavelength than the excitation photon (i.e.fluorescence light is a red-shift). This difference in energy or wavelength is known as stokes shift.† The difference in wavelength between positions of the band maxima of the absorption and emission spectra of the same electronic transition; figure (1-7). Solvent effects and excited state reactions can also affect the magnitude of stokes shift. Figure (1-7):-stokes shift of band maxima E = hÃŽ ½ = hÃâ€"c / ÃŽ » (1) h = Planck constant = 6.63 Ãâ€" 10-34 J.sec-1 c = light velocity ÃŽ ½ = light frequency Sec-1 or Hz ÃŽ » = wave length nm. Absorption energy EAbs.= hÃâ€"c / ÃŽ »Abs. (2) Emission energy Eem.= hÃâ€"c / ÃŽ »em. (3) Since: EemAbs. (4)so: ÃŽ »em.>ÃŽ »Abs (5) ÃŽ »em.,ÃŽ »Abs: emission and absorption spectra peaks respectively. When absorption and/or the emission spectra of a flourophore possess two or more bands, stokes shift is equal to the difference that separates the two most intense bands of the two spectra, figure (1-8). Figure (1-8):-stokes shift in a flourophore possess two bands If thermal energy is added to an excited state or compound has many highly populated vibrational energy levels, emission at shorter wavelengths than those of absorption occurs, this is called an anti-stokes shift and its often observed in dilute gasses at high temperatures. A key feature of fluorescence is the molecule spends a measurable Amount of time in the singlet state. Fluorescence life time refers to the average time that the molecule stays in its excited state before emitting a photon for fluorescence; it’s typically in the range (1-10 nsec.). Fluorescence radiant power (F) is proportional to the absorbed radiant power. F = É ¸ (P0 – P) - (6) É ¸: Fluorescence efficiency. P0: incident power. P: transmitted power. The relationship between the absorbed radiant power and concentration can be obtained from beers law P/P0 = 10-A- (7) P = P0 Ãâ€" 10-Ɇºbc - (8)F = É ¸ P0 (1–10-Ɇºbc)- (9) Structural factors. Fluorescence is expected in molecules that are aromatic or multiple conjugated double bonds with a high degree of resonance stability, it’s also expected with poly cyclic aromatic

Does Economic Wealth Lead to Well-Being

Does Economic Wealth Lead To Well-being? In 1974, USC Professor Easterlin put forward that within a country the rich have higher average subjective well-being (SWB) than the poor. Nevertheless, the average SWB is uncorrelated with income between rich countries and poor countries. For example, the Gallup poll of 2012 well-being from Livescience website (2011) shows that Panama has 61% of people who said they are thriving, which had a greater score than the USA. The modern economy based on the opinion that the growth in the economy can lead to SWB increases.Surprisingly, economic growth does not bring more happiness. Therefore, this is the Easterlin Paradox. One explanation is ignoring variables, in the first part of this essay, noneconomic factors such as health, environment or family will be discussed, and these factors will counteract the positives of wealth. Then the second part will account for why economic wealth cannot measure happiness. There is also a certain amount of opinion to support economic wealth give rise to happiness. It will be presented by discussing GDP issues in part three.Well-being does not only depend on economic factors, but it also be influenced by work, environment, health or family relations etc. The Weighted Index of Social Progress sees Sweden, Denmark and Norway on top, while the Happy Planet Index sees Colombia and Costa Rica among the leaders (Measures of Well-being, 2006). And a few South American countries’ SWB is as high as developed countries such as Puerto Rico, or Guatemala. The above cases show that economy is one of the elements in estimating SWB. It is evidence that economic wealth results in the working burden raising dramatically.Working pressure disrupts the staff’s life balance and thousands of work makes staff feel anxious every day. As the economy grows rapidly, the environment is polluted heavily. It is evident that the quality of environment decreasing gives rise to individuals’ SWB fall. Ano ther contributing factor is health which is regarded as the most important aspect by the majority of people. Better health conditions give people confidence as well as well-being. Sometimes, individuals are entangled with family issues, and the negative effects from family cancel out the positive effects from economic income.If a government considers increasing SWB, it should make more in policies that promote good governance, liberties, democracy, trust and public safety (Why Money Doesn’t Buy Happiness, 2011). Personal satisfaction lies in diverse factors, and earning does not play a major role. Section 2 will be devoted to the two explanations why GDP cannot measure the real SWB, especially in developed countries. A United Nations reported that the UK is only the 18th happiest place to live (British people are more miserable than Costa Ricans and Israelis, UN finds, 2012). Firstly, take case of a rabbit eats carrot.A rabbit finds a room filled with a large quantity of carr ots while the rabbit is going to starve to dying. Apparently the rabbit will gobble down the carrots, but the carrots will be become less attractive when the rabbit is almost full. According to the story, in rich countries the SWB rises up to a particular point, but it will never go beyond point. That is the reason why advanced countries (for example, USA, UK, France and Germany) SWB was not ranked in the top position. In reality, money is the carrot. The meaning of 100 dollars is significantly dissimilar between beggars and billionaires.When economy develops to a certain extent, economic factors cannot measure happiness because there are several variables to act on the SWB simultaneously. An amount of factors were introduced at the last paragraph. The second explanation is more psychological. The major determinant of SWB is the relative life condition (comparing with people in the same level) rather than the real life condition. Being more specific, if one individual has better liv ing condition than the other people who live in the same area, the one is more satisfied. This psychological comparison is called keep up with the Joneses.For this reason, the SWB will not change even if economic growth brings about rising incomes. For instance, on the one hand, country people live in the countryside and local residents lead the similar country life. On the other hand, people who live in urban areas lead completely diverse lives. Their social circles usually have a great number of affluent individuals, so the psychological pressure which is caused by the wealth comparison is greater than the happiness of high income. There are also positive views to support economic growth leads to SWB.To be empirical, countries with a lower GDP typically have more problems. Taking an example of Africa, according to the graph of geography of happiness from the Economist website (2010), countries at the bottom (mostly African) had lower score (The rich, the poor and Bulgaria, 2010). Most areas of Africa are rural. Africans now distinctly desire a better life. Although rich countries are clearly happier, the correlation is not perfect (The rich, the poor and Bulgaria, 2010). In the research of assistant professor Stevenson, they take a 0 to 10 life satisfaction scale to survey the work.People who live in the rich countries place themselves around 7 and 8. At the same time, people in the poor countries consider themselves at about 3. As the matter of fact, increasing GDP can raise average satisfaction. For instance, nations with booming GDP imply government can spend more capital on health care, education or environmental protection. It is not apparent that a lager GDP measures citizen’s health, education or intelligence directly, but it does continue to contribute to citizen’s life. This paragraph provides a summary and a discussion of some extensions of this paper.Firstly, basic needs are meet differences in well-being are less frequently due to i ncome, and more frequently due to factors such as social relationships and enjoyment at work (Why money doesn’t buy happiness, 2007), different variables influence SWB jointly. Secondly, two explanations were presented to interpret that GDP cannot measure the real SWB. The saturating point exists in the process of economic development promotes SWB, and then the economic factors will not be crucial. What is more, the psychological comparison is a vital determinant in SWB, though the income rising expressively brings plentiful happiness.Thirdly, GDP can increase national SWB authentically. To individuals, large income raises SWB in the short term. There are a number of separable components of SWB (Diener, 2000). Thus, money does not buy happiness. SWB is difficult to be calculated and can be measured in different ways. Happiness, as the ultimate goal, requires the most encompassing measure (measuring of well-being, 2006). Bibliography 1. Deutsche Bank Research, 2006, Measures o f Well-being. Available from http://www. dbresearch. com/PROD/DBR_INTERNET_EN-PROD/PROD0000000000202587. PDF [Accessed 19 April 2012] 2.Dinener, E. 2000. Subjective Well-being: The Science of Happiness and Proposal for a National Index. American Psychologist, vol. 55, No. 1, 34-43. 3. Livesciene, 2011, Top 19 Happiest Countries (and the 20 saddest). Available from http://www. livescience. com/13790-19-happiest-countries-20-saddest. html [Accessed 16 April 2012] 4. The Daily Beast, 2007, Why Money Doesn’t Buy Happiness. Available from http://www. thedailybeast. com/newsweek/2007/10/14/why-money-doesn-t-buy-happiness. html [Accessed 19 April 2012] 5. The Economist, 2010, Comparing Countries. The rich, the poor and Bulgaria.Money really can buy you happiness. Available from http://www. economist. com/node/17722557. html [Accessed 26 April 2012] 6. The Telegraph, 2012, British people are more miserable than Costa Ricans and Israelis, UN finds. Available from http://www. thetelegr aph. co. uk/lifestyle/9184916/British-people-are-more-miserable-than-Costa-Ricans-and-Isrealis-UN-finds. html [Accessed 4 May 2012] 7. Yale School of management, What Are the Economics of Happiness? Available from http://bpp. wharton. upenn. edu/betseys/press%20reaction/Easterlin%20Paradox/YaleSOMInterview. pdf [Accessed 26 April 2012]

Gay, Defined

Liz Schmidt Kate Brady English 101 October 9, 2012 Formal definition: Gay (adj. ) merry: happy and carefree; brightly ornamental or colorful; homosexual. (n. ) A homosexual. (â€Å"gay†) Synonymous definition: Gay (syn. ) merry, lighthearted, joyful, cheerful, sprightly, jolly, happy, joyous, gleeful, jovial, colorful, bright. (â€Å"gay†) Negative definition: Gay (adj. ) unhappy, lacking color, heavyhearted Because of the literal definition of the word, people that are homosexual are often seen as â€Å"colorful† and â€Å"cheerful†. Etymological Definition: Gay (n) usually male, homosexual.In middle English, it meant â€Å"excellent person† â€Å"noble lady† â€Å"gallant knight† or â€Å"something gay or bright†; â€Å"ornament or badge† (â€Å"gay†)2 Stipulative definition: Gay (adj. ) being homosexual Illustrative definition: Two men walking down the street holding hands. Thesis statement: The meaning of the w ord gay has changed vastly over time, which today, can be offensive. Liz Schmidt Kate Brady English 101 October 9, 2012 The definition of the word â€Å"gay† has evolved greatly over time. What you consider â€Å"gay† today is definitely not what was considered â€Å"gay† 200 years ago, or even 50 years ago. 00 years ago, the word was used as a term of promiscuity. It was also used as a slang term to call someone a â€Å"young hobo. † (â€Å"gay†) Today, we use the word mostly as â€Å"homosexual† or referring to someone who is attracted to the same sex. At the same time, the younger age group of America is using the word â€Å"gay† as a way to express dislike toward something. A common way would be saying â€Å"that’s gay† when a friend tells them their team lost the game. This misuse of the word can often lead to offending the homosexual community. The meaning of the word †gay† has changed vastly over time, which today, can be offensive.How did the meaning of the word â€Å"gay† once turn from being â€Å"merry and happy† to â€Å"homosexual†? It all started around the 1630’s, when people often used it as both â€Å"splendid and showily dressed† and calling a brothel a gay house. It is believed that the word was used this way up until about the early 1900’s. The slang meaning (homosexual) began to appear in psychological writing in the late 1940’s. At first, the word was used solely among homosexuals themselves, by mostly male prostitutes referring to each other, but also female prostitutes. â€Å"gay-rights movement†) It seems to me that nobody ever really used the term as its true meaning â€Å"merry and happy†. However, there are songs in old musicals where they use it that way, so I guess that meaning wasn’t completely extinct. Although the â€Å"merry and happy† meaning of gay wasn’t really used a whole lot in the past, we do see the â€Å"bright and colorful† meaning in many Christmas songs. One well-known example is in â€Å"Deck the Halls†. The lyrics are â€Å"Don we now our gay apparel†; this most likely implies that they were dressed in bright colors.Without doubt, the word â€Å"gay† has a boundless history and has been used so many different ways in the past. A teenager walks into their favorite store, and immediately spots something they love. They see that the price is much more than they have currently, and furiously groans, â€Å"Fifty dollars? That’s gay! † When someone says â€Å"that’s gay† about something that they find just plain stupid, why don’t they just say â€Å"that’s stupid†? The improper use of this word may offend the homosexual community because it is a lot like calling them stupid. From my observation, this whole â€Å"that’s gay† thing started recently, wit hin the last few years.Mostly young people started saying it about nearly everything that they found idiotic. It’s not even homophobic people using the word this way, it’s anybody. It’s a bad habit that most people probably picked up from hearing others say it. However if you say it wrongly you may be seen as homophobic. How can there be a double meaning of both â€Å"homosexual† and â€Å"stupid† for the word â€Å"gay†? Imagine if instead of â€Å"gay† people said â€Å"that’s straight† about an object they didn’t like. Wouldn’t it be wrong, to basically call someone’s sexuality bad or stupid?It sounds silly, but the inappropriate usage of the word â€Å"gay† is implying that you think there is something wrong with being gay. It’s obvious that someone who is gay is going to be offended if they hear someone using the word the wrong way. They could take it as insulting, or they could ju st be a little annoyed. Either way, it’s not right. I once worked with a girl who was homosexual. Sometimes I would easily forget that she was in the room and catch myself saying â€Å"that’s gay† about something totally random. I never really noticed that it could be offensive until a co-worker said something to me.She asked me, â€Å"Don’t you know Emily’s gay? † When I said yes, she then told me that I should stop saying â€Å"that’s gay† in front of her. At this point, I felt really bad about it and definitely wanted to stop saying it completely. Saying â€Å"that’s gay† is such a bad habit of many young people. I guess Emily understood that it was just a bad habit for me, but not everyone will be that understanding. Furthermore, the word â€Å"gay† should be used solely for meaning â€Å"homosexual†. The other day, I was conversing with a friend about some news in the media. She had told me that Brad Pitt makes 250 million dollars in just one sitting.I laughed, and replied, â€Å"that’s gay. † After I said that I realized I should definitely stop saying that because it doesn’t even make any sense if you think about it. The meaning of the word â€Å"gay† shouldn’t be â€Å"stupid†, although it is for many people. The definition has changed greatly throughout the years, which may cause some people to take offense by it. Works Cited â€Å"gay-rights movement. † The Columbia Encyclopedia. 2008. Credo Reference. Web. 8 Oct 2012. â€Å"gay. † Webster’s Dictionary and Thesaurus. 1997. Print. â€Å"gay. † Online Etymology Dictionary. Douglas Harper, 2012. Web. 8 Oct 2012.

Bumblebees, Genus Bombus

Bumblebees are familiar insects in our gardens and backyards. Still, you might be surprised by how much you dont know about these important pollinators. The genus name, Bombus, comes from the Latin for booming. Description Most people recognize the large, furry bees that visit backyard flowers as bumblebees. Fewer probably know that they are social bees, with a caste system of the queen, workers, and reproductives cooperating to meet the needs of the colony. Bumblebees range in size from about half an inch to a full inch in length. Patterns in their bands of yellow and black, along with the occasional red or orange, help indicate their species. However, bumblebees of the same species can vary quite a bit. Entomologists rely on other features, such as genitalia, to confirm a bumblebees identity. Cuckoo bumblebees, genus Psithyrus, resemble other bumblebees but lack the ability to gather pollen. Instead, these parasites invade Bombus nests and kill the queen. The Psithyrus bees then lay their eggs in the collected pollen in the conquered nest. This group is sometimes included as a subgenus of Bombus. Classification Kingdom - AnimaliaPhylum - ArthropodaClass - InsectaOrder - HymenopteraFamily - ApidaeGenus - Bombus Diet Bumblebees feed on pollen and nectar. These efficient pollinators forage on both wildflowers and crops. Adult females use modified hind legs equipped with corbicula to carry pollen to their offspring. Nectar is stored in the honey stomach, or crop, in the digestive system. Larvae receive meals of regurgitated nectar and pollen until they pupate. Life Cycle Like other bees, bumblebees undergo a complete metamorphosis with four stages to the life cycle: Egg – The queen lays eggs in a pollen clump. Then she or a worker bee incubates the eggs for four days.Larva – The larvae feed on pollen stores, or on regurgitated nectar and pollen provided by the worker bees. In 10-14 days, they pupate.Pupa – For two weeks, the pupae remain inside their silk cocoons. The queen incubates the pupae as she did her eggs.Adult – Adults assume their roles as workers, male reproductives, or new queens. Special Adaptations and Defenses Before flying, a bumblebees flight muscles must be warmed to around 86 Â °F. Since most bumblebees live in climates where cool temperatures may occur, they cannot rely on the ambient warmth of the sun to achieve this. Instead, bumblebees shiver, vibrating the flight muscles at a high speed but keeping the wings still. The familiar buzz of the bumblebee comes not from the wings themselves, but from these vibrating muscles. The bumblebee queen must also generate heat when she incubates her eggs. She shivers muscles in the thorax, then transfers the heat to her abdomen by contracting muscles down her body. The warmed abdomen stays in contact with the developing young as she sits on her nest. Female bumblebees come equipped with stingers and will defend themselves if threatened. Unlike their cousins the honey bees, bumblebees can sting and live to tell about it. The bumblebees sting lacks barbs, so she can easily retrieve it from the flesh of her victim and attack again if she chooses. Habitat Good bumblebee habitat supplies adequate flowers for foraging, especially early in the season when the queen emerges and prepares her nest. Meadows, fields, parks, and gardens all provide food and shelter for bumblebees. Range Members of the genus Bombus live mostly in temperate areas of the globe. Range maps show Bombus spp. throughout North and South America, Europe, Asia, and the Arctic. Some introduced species are also found in Australia and New Zealand. Sources Bumble bees - The Great Sunflower Project (article no longer available online)Bombus BiologyBumblebees: Their Behavior and Ecology, by Dave Goulson