Synthesis Polylactic Acid By Lipase Catalyzed Polymerization Biology Essay

Synthesis Polylactic Acid By Lipase Catalyzed Polymerization Biology Essay Polylactic acid (PLA), the biodegradable polymer, has received increasing attention as alternative materials in packaging and biomedical applications. The general method for synthesis of PLA using chemical-catalyzed polymerization produces the catalysts residues which are toxicity. Therefore, the enzymatic polymerization is a green alternative method to decrease this problem. Several researches attempt to improve the optimal condition for synthesis of PLA by using lipase as enzymatic-catalyzed. For an example, Lassalle et al. (2008) reported the synthesis of PLA by using lipase as biocatalyst and focused on the procedure. The results found that immobilized CAL-B was the most effective biocatalyst with 60% LA conversion and 55% recovered solid polymer in the reaction working at 60 Â °C for 96 h. Furthermore, Hans et al. (2009) researched to confirm the mild reactions conditions for the ring-opening polymerization of lactides by using Novozyme 435 (immobilized CAL-B) 12% wt. concentration in toluene to synthesize the polymer at 70 Â °C, D-lactide was catalyzed and 33% of monomer was converted and could be isolated a polymer with 25% yield for a number-average molecular weight of 3,300 g mol-1. Finally, Garcia-Arrazola et al. (2009) reported the synthesis of poly-L-lactide by used immobilized CAL-B (Novozyme 435) as biocatalyst for the ring-opening polymerization of L-lactide at 65 Â °C could be achieved using supercritical carbon dioxide (scCO2). The L-lactide monomer could be converted as the PLA with a molecular weight 12,900 g mol-1 under the condition at a biphasic scCO2/organic liquid system media and the optimum of temperature for the lipase activity. All of these present studies are the novel route to produce the polylactic acid and relate improvement of the new biomaterials. TABLE OF CONTENTS Page TABLE OF CONTENT i LIST OF TABLES ii LIST OF FIGURES iii INTRODUCTION 1 Lipase 1 Polylactic acid: PLA 2 Synthesis of polylactic acid: PLA 4 3.1 The conventional process for synthesis of PLA 4 3.2 Process for synthesis of PLA by lipase-catalyzed polymerization 5 Influence of several factors for the polymerization 6 Influence of the kind of lipase 6 Influence of the enzyme concentration 8 Influence of the monomer concentration 10 Influence of the temperature 11 The improvement of process for lipase-catalyzed synthesis of PLA 12 CONCLUSION 14 LITERATURE CITED 15 LIST OF TABLES Table Page Comparison of raw material type and possibility of recycling and biodegradation between PLA and PET polymer 3 Conversion (%) of LA, isolated enzyme after reaction, recovered PLA, and molecular weight (Mn) (Da) as a function of the kind of the different lipase 7 Results obtained for the ring opening polymerization of L-LA in scCO2 with 20 % (w/v) of L-LA and initial water content (aw) < 0.16 13 LIST OF FIGURES Figure Page 1 Chemical structure of Polylactic acid: PLA 2 2 Life cycle of PLA 3 3 Polymerization routes to PLA 4 4 Polymerization reactions to synthesize PLA 6 5 Lactide conversion as a function of reaction time for the ring opening polymerization of DD-lactide at 70 oC with a monomer to toluene ratio of 1:2 (g:mL) and use different concentration of Novozyme 435 8 6 Molecular weight as a function of conversion plots for the ring opening polymerization of DD-lactide at 70 oC with a monomer to toluene ratio of 1:2 (g:mL) and use different concentration of Novozyme 435 9 7 Lactide conversion as a function of reaction time for the ring opening polymerization of DD-lactide at different monomer to toluene ratio (monomer concentration) at 70 oC with 15 wt.-% of Novozyme 435 10 8 Lactide conversion as a function of reaction time for the ring opening polymerization of DD-lactide at different temperatures with 15 wt.-% of Novozyme 435 and a monomer to toluene ration 1:3 11 9 Number-average molecular weight as a function of temperature for the ring opening polymerization of DD-lactide at different monomer conversion with 15 wt.-% of Novozyme 435 and a monomer to toluene ratio 1:3 12 SYNTHESIS OF POLYLACTIC ACID BY LIPASE-CATALYZED POLYMERIZATION INTRODUCTION Lipase Lipases or triacylglycerol acylhydrolases EC 3.1.1.3 are hydrolase which catalyze the hydrolysis of triglycerides to glycerol and free fatty acids under aqueous conditions. In addition, lipases catalyze the tranesterification of other esters under micro-aqueous conditions. The ability of lipases has received increasing attention for used as catalyze in a wide array of biotechnology industry, such as food technology, detergent, chemical industry, cosmetic, organic synthesis, biomedical sciences and pharmaceutical applications (Gupta et al., 2004; Treichel et al., 2010). Lipases are produced by various plants, animals and microorganisms. Many microorganisms which are known as producers of extracellular lipases, including bacteria, yeast, and fungi. Especially, bacterial lipases and fungal lipases are most widely used as a class of commercial enzymes in many applications. The important commercial microbial lipases are Achromobacter sp., Alcaligenes sp., Arthrobactersp., Bacillus sp., Burkholderia sp., Chromobacterium sp., and Pseudomonas sp. from bacteria which are used successfully in the market with several products names, such as Lumafast, Lipomax, Combizyme and Greasex (Gupta et al., 2004). Moreover, fungi produces the important commercial lipases are Rhizopus sp., Aspergillus sp., Penicillium sp., Geotrichum sp., Mucor sp., and Rhizomucor sp. (Treichel et al., 2010) which are used in the market with many products names, such as Lecitase, Lipozyme, and Novozym 435 (CAL-B). Of these, the lipases from microbial have a stability, selectivity, and broad substrate specificity for cultivation such as an applications by used substances form oil mill wastewater, slaughterhouse wastewater, agroindustrial waste and corn steep liquor (Gupta et al., 2004; Treichel et al., 2010). Therefore, the recent microbial lipases have gained special industrial attention for used as biocatalyst in rapidly growing biotechnology. Polylactic acid Polylactic acid or the short name is PLA is a thermoplastic aliphatic polyester which a synthetic polymer based on lactic acid (LA) and have a helical structure was shown in Figure 1. PLA derived from the fermentation of renewable resources such as corn starch, tapioca products and sugarcanes. Figure 1 Chemical structure of Polylactic acid: PLA. PLA has received increasing attention as alternative materials in packaging and biomedical applications due to PLA is a biodegradable polymer, it easily degrades by simple hydrolysis of microorganisms under the appropriate conditions (Garlotta, 2001; Avinc and Khoddami, 2009). PLA has a high-strength, high-modulus, brightness, barrier properties and good moisture management as a result of its interesting for used in packaging and composite materials for clothing applications (Garlotta, 2001). Furthermore, PLA has a biocompatible and bioabsorbable properties which can be used for wide range applications in biomedical and pharmaceutical technology, such as surgical sutures, tissue engineering scaffolds, absorbable bone plates, artificial skin, and controlled drug-release systems (Lassalle and Ferreira, 2008; Avinc and Khoddami, 2009; Hans et al., 2009). Because of its compost based on a natural substance which make a biodegradability, PLA is to be a more environmentally-friendly polymer than poly ethylene terepthalate (PET) which is derived from a synthetic petrochemical-based materials due to PLA is lower greenhouse gas emission and significant energy savings, PLA avoids the problems related to plastic waste accumulation. The result of comparison between PLA and PET polymer was shown in Table 1. Table 1 Comparison of raw material type and possibility of recycling and biodegradation between PLA and PET polymer. Indexes PLA PET Initial raw material base Renewable plant stock Petroleum products Non-renewable resources Recycling of polymer wastes Total recycling possible Total recycling possible Biodegradation of polymer wastes Total Does not degrade Source: Avinc and Khoddami (2009) PLA products are easily composted or recycled under appropriate conditions at the end of the product life. The Figure 2 show the life cycle of PLA material degrades first by microbial hydrolysis, then the carbon dioxide and water which obtained from reaction became the basic necessities for a new growth and leading to produced lactic acid (LA) for re-used as a monomer in the production of a new PLA (Avinc and Khoddami, 2009). Figure 2 Life cycle of PLA. Synthesis of polylactic acid: PLA The synthesis of PLA starts with the extraction of sugars (e.g., glucose and dextrose) from natural substances which used as a substrate in fermentation of lactic acid by microorganisms. Lactic acid (LA) is the starting material for the PLA production process, through polymerization. There are two major routes to synthesize PLA from LA monomer which are showed in Figure 3 (Avinc and Khoddami, 2009). Figure 3 Polymerization routes to PLA. From the Figure 3, polymerization routes to PLA are distributed as two processes, the first route is a polycondensation polymerization and the second route is a ring opening polymerization. The conventional process for synthesis of PLA The production process to synthesize PLA by polycondensation of LA is the conventional process for making PLA. This process need to carry out under high vacuum and high temperature, solvent is used to extract the water through the condensation reaction (Avinc and Khoddami, 2009). However, PLA polymer products obtained tends to have low molecular weight. Therefore, the second route is improved by ring opening polymerization of LA which is condensed of water and then converted into cyclic dimer of LA or lactide for used as a monomer in ring opening polymerization. PLA polymer products obtained higher molecular weight than the first route and used milder conditions. Polymerization of PLA need to use a catalyst for supporting the conversion of LA to PLA. The catalysts are divided into two types, the first is the chemo-process which is the polymerization by used a metal as a catalyst and the second is the bio-process which is the polymerization by used a LA-polymerizing enzyme as a catalyst. The chemo-process made the residues of heavy metals based catalysts, such as oxides of Zinc (Zn) and Stannum or Tin (Sn) which are toxicity. Furthermore, the process need high purity monomers, high temperature and high vacuum for serving conditions reactions. On the other hand, the bio-process used an enzyme based catalysts such as lipases which are non-toxic. Also, PLA polymer products can be used for biomedical and pharmaceutical applications. Moreover, polymerization reaction can be run under mild and environmentally-friendly conditions (Taguchi et al., 2008; Lassalle and Ferreira, 2008; Hans et al., 2009). Process for synthesis of PLA by lipase-catalyzed polymerization From the advantages of the bio-process or the enzymatic-catalyst polymerization, there are several researches attempts to synthesize PLA by used enzyme as catalyst such as lipase-catalyzed in the ring opening polymerization. The reaction of polymerization can be set up follow with the Figure 4. In the reactor compounded with LA, lipase, solvent and purge gas which is used for protection to occur of the regeneration of PLA. Furthermore, the total reactions need to control the optimal temperature and reaction time. Figure 4 Polymerization reactions to synthesize PLA. The measurements which used to represent the properties of PLA polymer products are considered in several parameters. The important of evaluations are the conversion of LA, the molecular weight of PLA polymer products, the recovery of PLA and the recovery of lipases at the end of reactions. Influence of several factors for the polymerization Production of a good PLA, must be use a good set up reaction of polymerization. Otherwise, the influence of the several factors such as a kind of lipases, enzyme concentration, monomer concentration and temperature needs to be considered together. Influence of the kind of lipase Lassalle et al. (2008) researched the influence of the kind of lipase for the synthesis of polylactic acid (PLA) by using the three kind of lipases as biocatalysts. Porcine pancreatic lipase (PPL) from mammalian, Candida antarctica lipase B (Immobilized CAL-B) from fungal, and Pseudomonas cepacia (PCL) from bacterial origin were used in the experiment. The reaction was carried out by operating of LA, lipase, and solvent at 60 oC for 96 h. The performance of the three lipases was evaluated in a term of the conversion of LA to PLA and expressed as percentage (%) conversion. Table 2 Conversion (%) of LA, isolated enzyme after reaction, recovered PLA, and molecular weight (Mn) (Da) as a function of the kind of the different lipase. Enzyme % Conversion % recovered PLA % recovered lipase Mn (Da) Imm.CAL-B 58 55 85 446 PCL 88 12 34 400 PPL 96 2 90 768 Source: Lassalle and Ferreira (2008) The result was presented in the Table 2, using the immobilized CAL-B as catalyst obtained 58% conversion of LA, 55% recovered PLA, 85% recovered lipase, and 446 Da of Molecular weight. For using PCL as catalyst obtained 88% conversion of LA, 12% recovered PLA, 34% recovered lipase, and 400 Da of Molecular weight. For using PPL as catalyst obtained 96% conversion of LA, 2% recovered PLA, 90% recovered lipase, and 768 Da of Molecular weight. From the result found that higher conversion levels were measured in the case of soluble enzymes, but only traces of solid polyesters were recovered in this cases. In contrast, amounts of solid PLA were recovered using immobilized CAL-B, and the conversion was lower than soluble lipases. For the conclusion of the experiment, the immobilized CAL-B was the most effective biocatalyst with 60% conversion of LA and 55% recovered solid polymer in the reaction working at 60 oC for 96 h. Influence of the enzyme concentration There are several researches used the immobilized CAL-B lipase for esterification reaction due to its high catalytic activity but it does not propagate in polymerization reaction. So, Hans et al. (2009) researched to confirm the synthesis of PLA by immobilized CAL-B (Novozyme 435) catalyst in ring opening polymerization of lactide. The reaction was improved by adding nitrogen gas into the reactor for protected regeneration of PLA to LA and used toluene as a solvent for enzymatic polymerization. The objective of this study is find an optimal reaction condition such as enzyme concentration, monomer concentration and optimal temperature. Figure 5 Lactide conversion as a function of reaction time for the ring opening polymerization of DD-lactide at 70 oC with a monomer to toluene ratio of 1:2 (g:mL) and use different concentration of Novozyme 435. The first factor is influence of the enzyme concentration. The result was presented in Figure 5, the overall monomer conversion increases when increasing amounts of enzyme. The reaction catalyzed with 25 wt.-% of enzyme up to 100% monomer conversion after 2 days, while the reaction catalyzed with 10 wt.-% of enzyme up to only 25% monomer conversion. Figure 6 Molecular weight as a function of conversion plots for the ring opening polymerization of DD-lactide at 70 oC with a monomer to toluene ratio of 1:2 (g:mL) and use different concentration of Novozyme 435. In contrast, the relation of molecular weight and conversion are represented in Figure 6. The result found that 25 wt.-% of enzyme obtained the molecular weight of PLA lower than 15 wt.-% of enzyme and 10 wt.-% of enzyme at the same conversion due to higher enzyme concentrations have more water which is introduced into the reaction and leads to a decrease of the molecular weight. Amounts of water within the reaction have an influence for the molecular weight PLA polymer products (Hans et al., 2009). The normal of reaction for synthesis PLA by lipase-catalyst distribute into 3 step, the first step is the monomer activation which is the combination of lipases and lactic acid (LA), then the lipase-LA combine with water for extension of pre-polymer and release the component of lipase-OH in the initiation step, the last step is the chain propagation which increase the number of monomer within polymer chain. In any case, if there is a lot of water in the reaction, it will occur the conformation of the other component as free water and a linkage between lipase and water by loosely bound and tightly bound. The free water and lipase-water loosely bound can break the polymer chain in the initiation and affect to decrease a molecular weight of PLA polymer products. Influence of the monomer concentration Hans et al. (2009) studied influence of the monomer concentration by expected that increasing monomer concentration, the polymerization rate and the overall monomer conversion will increase. Figure 7 Lactide conversion as a function of reaction time for the ring opening polymerization of DD-lactide at different monomer to toluene ratio (monomer concentration) at 70 oC with 15 wt.-% of Novozyme 435. From the Figure 7 observed at the monomer to toluene ratio 1:2 and 1:3, the high conversion increase and then decrease when the monomer concentration decrease. Exclusion a monomer to toluene ratio 1:1, the conversion is also lower which might result from a poor solubility of the substrate and the precipitation of PLA. For the conclusion of the experiment, the immobilized CAL-B was the most effective biocatalyst with 33% of monomer was converted and could be isolated a polymer with 25% yield for a number-average molecular weight of 3,300 g mol-1. Influence of the temperature Furthermore, Hans et al. (2009) expected that the temperature affect to PLA polymer products in ring opening polymerization as show in the Figure 8. Figure 8 Lactide conversion as a function of reaction time for the ring opening polymerization of DD-lactide at different temperatures with 15 wt.-% of Novozyme 435 and a monomer to toluene ration 1:3. From the Figure 8 observed that increasing temperature, the monomer conversion decrease. At 80 oC and 90 oC, a monomer conversion does not exceed 25 % in 2 days while at 60 oC and 70 oC, a monomer conversion reaches about 60 % and at 50 oC, a monomer conversion reach to 80 %. In the case of ring opening polymerization of lactide by lipase-catalyst at higher temperature might induce an enhanced deactivation of the enzyme which led to low monomer conversion. Figure 9 Number-average molecular weight as a function of temperature for the ring opening polymerization of DD-lactide at different monomer conversion with 15 wt.-% of Novozyme 435 and a monomer to toluene ratio 1:3. The relative of molecular weights and temperatures at different conversions are presented in the figure 9, at 60 % and 50 % conversion obtained a highest molecular weights at 60 oC and drop off at higher temperatures. Explanation is an increase temperature release of free and loosely bound water which make denaturation of the enzyme. The other reason is a decrease in temperatures also induces a lower solubility of the polylactide and affect difficult to maintain a homogeneous solution. The improvement of process for lipase-catalyzed synthesis of PLA From the study about the influence of several factors for ring opening polymerization by lipase-catalyst observed that the enzymatic synthesis of PLA by use volatile organic compounds solvent do not encouraging due to a poor solubility of the substrates in polymerization reactions. In addition, the high temperature to reach the melting point of LA at 92 oC-95 oC might cause partial enzyme deactivation (Garcia-Arrazola et al., 2009). Garcia-Arrazola et al. (2009) improved the polymerization reaction to obtain PLA by used supercritical carbon dioxide (scCO2) as a solvent replacement of the volatile organic compound (VOCs). The advantage of scCO2 is non-expensive, non-flammable, non-toxic, low melting point, low viscosity, high diffusion coefficient, and friendly in synthetic processes. Table 3 Results obtained for the ring opening polymerization of L-LA in scCO2 with 20 % (w/v) of L-LA and initial water content (aw) < 0.16. Entry Biocatalyst (wt%) Time (days) Polymer yield (%) 1 10 1 5.70 2 10 2 9.77 3 10 3 11.03 4 10 4 1.64 5 15 1 3.2 6 15 3 5.16 7 15 5 5.35 8 15 7

Nurse Practitioner - Personal Narrative Essays -- Volunteer Volunteeri

Recently, I was able to take a trip down to Tijuana, Mexico, where I had the opportunity to volunteer at an orphanage for ten days. While at the orphanage, I was able to help build a sidewalk and a garage for a family who was fleeing domestic violence. During my trip I experienced one of the greatest feelings in my life, which was the complete self-fulfillment and joy in helping another human being. I knew from then on helping people and having the privilege to serve others would be something I would want to do as lifetime career. Thus, combining my love for helping people and my interest in the medical field, I decided to research the occupation of being a nurse practitioner to see if this would be a suitable career option for me in the future. As a nurse, you can generally plan when you will work and for how long, but your day will be anything but routine. Depending on the area of specialty, nurse practitioners are employed in hospitals, clinics, physicians’ offices, nursing homes, mental health centers, hospices, prisons, and other health care settings (Nurse Practitioner Vocational,69).As you can see ,n all most all instances this occupation takes place indoors in a formal setting. Also, since this occupation is set in a formal setting you can expect that wearing a uniform is mandatory. Much of these dress codes include wearing scrubs, a lab jacket, and often gloves or masks so that nurses may protect themselves and their patients (Nurse Practitioner Oregon, 1). Furthermore, an average nursing shift is eight hours long, with the option of working a day shift, evening shift, or a night shift (Morkes Encylopedia, 71). All of... ...ion, throughout researching this paper I became more and more attracted to the possibility that I might someday become a nurse practitioner. One of the most important things I learned is that the educational requirements to become a nurse practitioner were much more appealing to me than those required of a physician. Also, I learned that this occupation is one that has employment opportunities across the world, which is perfect for me since I would love to be able to help people all over the globe. Finally, in the future I would definitely consider pursuing this occupation. This career has so many different aspects that fit perfectly into my idea of a dream job. Plus it would give me the opportunity to make a difference in people’s lives on a daily basis, which in my opinion is one of the best career options available.

Buck’s Dilemma Essay

Solution 1 — Classification with the Statement of Cash Flows Buck should present the borrowing and payment activity as a cash flow from financing activities. ASC 230-10-45-14 states that â€Å"proceeds from issuing bonds, mortgages, notes, and from other short- or long-term borrowing† are a cash inflow from financing activities. Similarly, ASC 23010-45-15 states that â€Å"repayments of amounts borrowed† are a cash outflow for financing activities. Solution 2 — Gross versus net presentation Scenario 1 Net presentation is appropriate. Buck may classify the activity as a $50 million net cash inflow ($100 million in total draws less the $50 million repayment) within the financing activities section of the statement of cash flows. Buck’s activities in Scenario 1 are broadly consistent with the requirements for net presentation under ASC 230-10-45-8 and 45-9. Specifically, the draws and payments on the facility can be considered large in relation to the maximum borrowing capacity (Buck actually reached its maximum borrowing capacity before making any repayments). The volume of the transactions is assumed to be large (note, in practice, this determination typically involves judgment and is dependent upon individual facts and circumstances). In addition, the terms of both draws stipulate that all amounts are due on demand; therefore, Buck should consider the draws as having original maturities of three months or less. ASC 230-10-45-9 only permits net presentation when borrowings have original maturities of three months or less. Scenario 2 The activity related to Buck’s first draw and subsequent repayment should be presented on a gross basis within the financing activities section as a $60 million inflow for the draw on July 15, 2010, and a $60 million outflow for the repayment on December 15, 2010. The activity related to Buck’s second  draw and subsequent repayment may be presented on a net basis within the financing activities section. The $40 million draw on September 30, 2010, and the repayment on December 1, 2010, net to zero for annual reporting purposes. Buck’s activities related to both of the draws in Scenario 2 once again reflect some of the characteristics within the cash flow statement guidance. The transactions can be considered large in relation to the maximum borrowing capacity, and the volume of activity is assumed to be large (note, in practice, these determinations typically involve judgment and are dependent upon individual facts and circumstances). Unlike Scenario 1, the terms of the draws do not consider the draws to be due on demand to Buck’s bank. Rather, the first draw has an original maturity of six months, and the second draw has an original maturity of three months or less. Therefore, in accordance with ASC 230-10-45-9, Buck must present the activity related to the first draw on a gross basis because the original maturity is greater than three months. In turn, net presentation is appropriate for the second draw since it has an original maturity of three months or less. Scenario 3 Buck should present all borrowing and payment activity under the Facility on a gross basis within the financing activities section of the statement of cash flows. The draws on the Facility do not have any specific repayment provisions other than the overall expiration date of the Facility as of December 31, 2012. While the activity does have some of the factors needed to consider net presentation, including large dollar amounts in relation to the maximum borrowing capacity and large volumes of transactions (see notes in Scenarios 1 and 2 above), the draws do not have an original maturities of three months or less. Under the provisions of Scenario 3, the only activities that Buck could potentially present net within its statement of cash flows are transactions occurring on or after October 1, 2012. Said differently, only draws occurring within three months of the Facility’s expiration would be considered to have original maturities of three months or less. Solution 3 — IFRSs Under IFRSs, IAS 7 is the primary source of guidance for determining how to present information about the cash flows of an entity within the financial statements. IFRSs and U.S. GAAP are broadly consistent regarding net versus gross presentation. Similar to U.S. GAAP, IFRSs generally require entities to present information about an entity’s amounts of cash receipts and cash payments during a period on a gross basis. However, in certain circumstances, IFRSs permit certain cash flow activities to be presented on a net basis. Paragraph 22(b) of IAS 7 states that cash flows may be reported on a net basis when â€Å"cash receipts and payments for items in which the turnover is quick, the amounts are large, and the maturities are short.† This guidance is generally consistent with the provisions of ASC 230-1045-8. Further, paragraph 23A of IAS 7 provides the following examples of cash receipts and payments that may be presented net under the criteria set forth in paragraph 22( b): a. principal amounts relating to credit card customers; b. the purchase and sale of investments; and c. other short-term borrowings, for example, those which have a maturity period of three months or less. Accordingly, under IFRSs, an entity’s cash inflows and outflows associated with a revolving line of credit may potentially be presented on a net basis within the financing activities section of the statement of cash flows, provided the aforementioned criteria are met. Therefore, the conclusions under IFRSs for each scenario in this case would be consistent with that reached under U.S. GAAP.

Major Sub-Disciplines of Geography

The field of geography is a vast and wondrous academic field with thousands of researchers working in dozens of interesting sub-disciplines or branches of geography. There is a branch of geography for just about any subject on Earth. In an effort to acquaint the reader with the diversity of the branches of geography, we summarize many below. Human Geography Many branches of geography are found within human geography, a major branch of geography that studies people and their interaction with the earth and with their organization of space on the earths surface. Economic GeographyEconomic geographers examine the distribution of production and distribution of goods, the distribution of wealth, and the spatial structure of economic conditions.Population GeographyPopulation geography is often equated with demography but population geography is more than just patterns of birth, death, and marriage. Population geographers are concerned with the distribution, migration, and growth of population in geographic areas.Geography of ReligionsThis branch of geography studies the geographic distribution of religious groups, their cultures, and built environments.Medical GeographyMedical geographers study the geographic distribution of disease (including epidemics and pandemics), illness, death and health care.Recreation, Tourism, and Sport GeographyThe study of leisure-time activities and their impact on local environments. As tourism is one of the worlds largest industries, it involves a great number of people making very temporary migrations and is thus of great interest to geographers.Military GeographyPractitioners of military geography are most often found in the military but the branch looks not only at the geographic distribution of military facilities and troops but also utilizes geographic tools to develop military solutions.Political GeographyPolitical geography investigates all aspects of boundaries, country, state, and national development, international organizations, diplomacy, internal country subdivisions, voting, and more.Agricultural and Rural GeographyGeographers in this branch study agriculture and rural settlement, the distribution of agriculture and the geographic movement and access to agricultural products, and land use in rural areas.Transportation GeographyTransportation geographers research transportation networks (both private and public) and the use of those networks for moving people and goods.Urban GeographyThe branch of urban geography investigates the location, structure, development, and growth of c ities — from tiny village to huge megalopolis. Physical Geography Physical geography is another major branch of geography. It is concerned with the natural features on or near the surface of the earth. BiogeographyBiographers study the geographic distribution of plants and animals on the earth in the subject known as biogeography.Water ResourcesGeographers working in the water resources branch of geography look at the distribution and use of water across the planet within the hydrologic cycle and of human-developed systems for water storage, distribution, and use.ClimateClimate geographers investigate the distribution of long-term weather patterns and activities of the earths atmosphere.Global ChangeGeographers researching global change explore the long-term changes occurring to planet Earth based on human impacts on the environment.GeomorphologyGeomorphologists study the landforms of the planet, from their development to their disappearance through erosion and other processes.Hazards GeographyAs with many branches of geography, hazards combine work in physical and human geography. Hazard geographers research extreme events known as hazards or disaster and explore the human interac tion and response to these unusual natural or technological events.Mountain GeographyMountain geographers look at the development of mountain systems and at the humans who live in higher altitudes and their adaptations to these environments.Cryosphere GeographyCryosphere geography explores the ice of the earth, especially glaciers and ice sheets. Geographers look at the past distribution of ice on the planet and ice-cause features from glaciers and ice sheets.Arid RegionsGeographers studying arid regions examine the deserts and dry surfaces of the planet. The explore how humans, animals, and plants make their home in dry or arid regions and the use of resources in these regions.Coastal and Marine GeographyWithin coastal and marine geography, there are geographers researching the coastal environments of the planet and how humans, coastal life, and coastal physical features interact.Soils GeographySoil geographers study the upper layer of the lithosphere, the soil, of the earth and it s categorization and patterns of distribution. Other major branches of geography include: Regional Geography Many geographers focus their time and energy on studying a specific region on the planet. Regional geographers focus on areas as large as a  continent  or as small as an urban area. Many geographers combine a regional specialty with a specialty in another branch of geography. Applied Geography Applied geographers use geographic knowledge, skills, and techniques to solve problems in everyday society. Applied geographers are often employed outside of academic environment and work for private firms or governmental agencies. Cartography It has often been said that geography is anything that can be mapped. While all geographers know how to display their research on maps, the branch of  cartography  focuses on improving and developing technologies in map-making. Cartographers work to create useful high-quality maps to show geographic information in the most useful format possible. Geographic Information Systems Geographic Information Systems  or GIS is the branch of geography that develops databases of geographic information and systems to display geographic data in a map-like format. Geographers in GIS work to create layers of geographic data and when layers are combined or utilized together in complex computerized systems, they can provide geographic solutions or sophisticated maps with the press of a few keys. Geographic Education Geographers working in the field of  geographic education  seek to give teachers the skills, knowledge, and tools they need to help combat geographic illiteracy and to develop future generations of geographers. Historical Geography Historical geographers research the human and physical geography of the past. History of Geography Geographers working in the history of geography seek to maintain the history of the discipline by researching and documenting the biographies of geographers and the histories of geographic studies and geography departments and organizations. Remote Sensing Remote sensing  utilizes satellites and sensors to examine features on or near the earths surface from a distance. Geographers in remote sensing analyze data from remote sources to develop information about a place where direct observation is not possible or practical. Quantitative Methods This branch of geography uses mathematical techniques and models to test  hypothesis. Quantitative methods are often used in many other branches of geography but some geographers specialize in quantitative methods specifically.