air creebec inc. is a regional airline based in val-d'or , quebec , canada .

it operates scheduled and charter services to 16 destinations in quebec and ontario .

its main base is val-d'or airport , with a hub at timmins/victor m. power airport .

air creebec

air creebec <EOT> ‡ aeroplan miles accumulated on air creebec do not count towards air canada altitude status .

his involvement in the aviation industry includes white river air services , norontair , austin airways , air creebec , air ontario , air manitoba , air alliance and canada 3000 airlines .

air creebec will not accept more than three ( 3 ) um passengers per flight .

earn up to 100 % of the miles you fly for each eligible air creebec flight .

all scheduled flights operated by air creebec are eligible * . effective april 1 , 2018 .

an air creebec plane went off a taxiway at trudeau airport monday for an unknown reason .

air creebec hub - airports used as transfer points to get passengers to their intended destination .

note : air creebec will not accept a um passenger who has a connection onto another airline .

all scheduled flights operated by air creebec are eligible * . up to march 31 , 2018 .

air creebec is quite permissive of passengers ' needs , from bringing animals along to flying with children .

looking for cheap flights with air creebec ? use skyscanner to browse air creebec flights and find the lowest prices and most convenient air creebec flight times for your travel needs . follow the links and book your cheap flight directly with the airline or travel agent for the best price – skyscanner doesn ' t add any commission .

air creebec is one of canada’s premier northern air transportation companies , serving 16 destinations in ontario and québec - from montréal to moosonee , from timmins to val d’or .

air creebec does not provide oxygen for passenger use . the passenger has to have his / her own oxygen tank .

• air creebec will not accept a child under 5 years old travelling alone . this child must be accompanied by an adult at least 18 years of age .

skyscanner allows you to find the cheapest flights with air creebec without having to enter specific dates or even destinations , making it the best place to find cheap flights for your trip .

air creebec is committed to providing top - quality airline services in quebec and ontario . we have worked very hard over the past quarter century to achieve our vision of reliable and comfortable air travel to the north . the pursuit of excellence is our primary and unwavering focus .

baggage fees are typically not included for this airline . pre - pay for baggage directly with the airline before departure to avoid higher charges at the airport . for air creebec baggage info , please click here .

air creebec will accept for transportation , without fees , a service animal required to assist a person with a disability provided the animal is properly harnessed and certified in writing , as being trained by a professional service animal institution .

legroom and seat selection are adaptable to meet the needs of air creebec customers . their aircraft fleet consists of 21 transports , which includes a dash 8 - 300 , dash 8 - 100 , king air 100 , and hs748 . the dash 8 - 300 seats up to 46 passengers , the dash 8 - 100 seats up 37 passengers , the king air seats 8 , and the hs748 can carry up to 5 . 851 . 8 kg .

. flightnetwork offers you the ability to book your flights with price drop protection , for free . if the price of your air creebec itinerary drops after you book , we ' ll credit you the difference . that ' s how we roll .

air creebec 101 fecteau street val d ' or arpt . val d ' or , qc canada j9p 4p4 tel : 819 - 824 - 8355 , 800 - 567 - 6567 • fax : 819 - 825 - 0600 email : ac . cebeercria @ yxuorel

air creebec inc . ’s beginnings date back to 1982 . following ratification of the james bay and northern quebec agreement , the cree nation was faced with a unique opportunity to extend its activities to the field of transportation . the cree nation was a promising market and needed an air carrier whose main objective would be to meet its expectations . we started with one aircraft and we are growing .

nemaska is now accessible by air through daily flights by air creebec and is linked to both the james bay highway , which leads into abitibi temiscamingue and the route du nord leading into chibougamau . the community features two hotels , and hosts the cree regional authority head offices , a newly constructed band office , a postal office , a community wellness center , the luke mettaweskum school , and a newly constructed church .

i ) the minimum charge of $ 125 . 00 plus taxes is applied . if the weight of the animal exceeds the minimum charges , the charge will be calculated as per cargo procedures ( weight multiplied by tariff ) . if same day delivery is requested , air creebec express charges will be applied .

— the centre air creebec , formerly known as the palais des sports , is a 3 , 504 capacity ( 2 , 140 seated ) multi purpose arena in val d or , quebec , canada . it is home to the val d or foreurs ice hockey team . it was built in 1949 and renamed for… …

3 hawker hs748 turboprops , 2 dhc8 dash 8 - 300 regional turboprops , 14 dhc8 dash 8 - 100 regional turboprops , 3 beech king air 100 turboprops .

children between the ages of 5 - 11 years will be accepted for transportation , unaccompanied by a passenger 18 years of age or older , anywhere in the air creebec system , provided at the time of acceptance , and unaccompanied minor service request form is completed and signed by the person checking in that child for the flight . the parent who is checking in the child must stay at the airport until the flight has departed .

it was owned by harvey friesen ( president ) , cliff friesen ( executive vice - president ) , karl friesen ( vice president of operations ) , rick baratta ( vice president of finance ) and brad martin ( director of operations ) , but in 2010 it was sold to exchange income corporation ( eic ) for $ 32 million . eic also owns calm air , perimeter aviation , and keewatin air . bearskin has 240 employees . [ 2 ]

may 1 , 1995 : flight 362 , a swearingen metroliner , collided with an air sandy piper navajo chieftain while on approach to sioux lookout airport , destroying both aircraft and killing all persons on both aircraft , a total of 8 dead . [ 12 ]

bearskin lake air service lp , operating as bearskin airlines , is a regional airline based in sioux lookout , ontario , canada . it operates services in northern ontario and manitoba . its main bases are sioux lookout airport ( yxl ) and thunder bay international airport ( yqt ) , with a hub at greater sudbury airport ( ysb ) . [ 2 ]

january 29 , 2003 : a beechcraft 99 climbed and entered a turn , but the captain had trouble seeing the artificial horizon . the first officer called that the aircraft was in a 2000 feet per minute descent . he then took control , but was not fast enough to prevent the aircraft from striking a frozen lake and bouncing back into the air . believing that both propellers were damaged , he then crash landed on the lake . no fatalities were reported . [ 14 ]

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* * * current information , directly from the official canadian civil aircraft register database . * * *

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this web site has been setup to help you cut through the jungle of all those codes and abbreviations used in and around the airline industry . whether it be an aircraft type code in a printed timetable or an airline code in online booking system or on your ticket this site has been designed to help you find out what that code stands for . so if you want to know what type of aircraft an ab6 is that your bookings says you will be flying on or what airport yyz is that you are flying from or to , this is the place to look .

we welcome business leaders , mining employees and a range of other private sector clients across canada . corporate shuttles and charter flights for executives .

new schedule effective april 30th , 2018 . download the electronic version ( pdf ) click here new schedule effective july 9th , 2018 . download the electronic version ( pdf ) click here

1 ) for passengers going through security ( yvo , ymt and yul ) : anyone who appears 18 years or older , must present one government issued photo i . d . or two pieces of government issued non - photo i . d . with at least one of these containing name , date of birth and gender .

same as above . anyone under the age of 18 must be properly be identified by the parent or guardian .

2 ) baggage weight allowance per passenger ( excluding infants ) of 44lbs / 20kg – excess fees will be charged if necessary . note : there is no extra charge for wheelchairs , strollers , car seats and any other device that the passenger needs to function normally . however , there is no baggage allowance for infants . – unless a seat has been purchased for the baby .

3 ) make sure all baggage has a name tag and is properly identified .

1 ) passengers are to check in at least 45 minutes before scheduled departure .

carry - on baggage may consist of no more than one small piece other than a small purse ( 10x12x8 inches ) . all carry - on baggage must fit in the sizing device at the check - in counter and must be stored either under the seat or in the overhead compartment onboard the aircraft . the maximum weight for the carry on is 13lbs ( 6kgs ) on the dash 8 .

note : baggage skycheck service is available between yulyvoyul and yulymtyul only . the weight of the skycheck baggage is included in the 44lbs allowance for checked baggage and is limited to one piece per passenger and must fit in the test device .

live animals must be stowed in approved hard shell kennel ( no soft shell kennels / container ) and will be placed in the baggage compartment . upon request , size permitting , an approved kennel may be stowed under the passenger’s seat . we do not accept wire cages .

live animals will be treated separately and is not part of the chargeable excess baggage .

ii ) note : the minimum charge is always applied , regardless if the passenger is travelling with no luggage .

i ) the minimum charge of $ 125 . 00 plus taxes is applied .

iii ) the maximum allowable weight for both the animal and in - cabin pet kennel must not exceed 6kg / 13lbs and the maximum size must not exceed 9″x10″x15″ ( 22 . 5cmx25cmx37 . 5cm ) .

iv ) the kennel must be stored under the seat directly in front of the passenger and the animal must remain in the kennel for the entire duration of the trip .

seeing - eye dog , hearing - ear or search and rescue dogs etc . will be permitted in the cabin when accompanying a passenger dependant on them . the dog must be harnessed and remain with the passenger but is not allowed to occupy a seat or restrict access to an aisle or exit .

• all children two ( 2 ) years or older must be ticketed and assigned a seat .

• one ( 1 ) adult who is at least 18 years old may accompany an unlimited number of children under 11 years old but not more than one ( 1 ) infant .

• infant ( inft ) – passengers under the age of two ( 2 ) must be travelling with an adult of at least 18 years or older and that adult can travel with only one infant .

a fee of $ 40 . 00 plus taxes per minor child , each direction will be charged for using the um service . this is a non - refundable charge . when two or more minors are travelling together , only one ( 1 ) um service charge in each direction will apply .

we accept responsibility for their care from the time of check - in at the airport of departure until they are handed over to the designated person meeting that child at the airport of destination .

* advise person who brought the um to the counter to leave the airport only once the flight has departed * .

a pregnant passenger who is in her 36th weeks of pregnancy must fill a “pregnancy medical clearance form” having been examined by a physician or qualified personnel within 72 hours of flight departure and is physically fit to travel .

this form must be submitted in duplicate by the passenger to the counter agent at check - in and a copy is given to the flight attendant prior to the flight .

they are entitled to ( 2 ) oxygen tanks , which will be placed in a container . one which they will keep in front of them for use , the other stowed under their seat . we accept a maximum of one ( 1 ) type d oxygen tank per container . there are two containers on each dash - 8 aircraft only .

the canadian aviation security regulations ( casr ) does not allow anyone with a loaded weapon onboard an aircraft nor to have access to ammunition onboard . a peace officer , this includes bodyguards who are members of a police force assigned to government ministers for protection and game wardens are allowed to travel onboard with an unloaded firearm under certain conditions : 1 ) the officer informs the carrier prior to departure time . 2 ) the “notice to armed individuals and escort officers” form must be completed and the proper identification with the officer’s full facial picture and signature and the signature of an authorized representative of the organization employing the peace officer . 3 ) the firearm and ammunition are separated . ammunition must be checked as checked luggage . it must be properly packed and weigh no more than 5 kg .

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passengers need to check in at least 45 minutes before their scheduled departure . anyone 18 or older needs to present a government - issued photo identification or two pieces of government - issued non - photo identification . children under 18 must be properly identified by their parent or guardian .

the airline allows a total baggage weight of 20 kg per passenger , and anything above that will be charged extra . however , there is no extra charge for wheelchairs , strollers , or car seats . for carry - ons , passengers are allowed only one small piece other than a small purse ( 10 inches x 12 inches x 18 inches ) . the maximum weight is 6 kg on the dash 8 plane .

people with disabilities may bring a service animal into the cabin for no fee , as long as the animal is properly harnessed and certified . as for other live animals , they must be kept in hard - shell kennels and either placed in the baggage compartment or , size permitting , stored under a seat . a minimum charge of $ 125 plus taxes will apply .

all children 2 years or older must be ticketed and assigned to a seat , but one adult who is at least 18 years old can accompany an unlimited number of children under age 11 and no more than one infant . children ages 5 - 11 can fly unaccompanied as long as the adult checking them in has completed the unaccompanied minor service request form . this adds a $ 40 fee per minor .

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nemaskau eenouch have a rich and remarkable heritage that defines their collective identity and specific worldview .

life in the bush has characterised most of this history and has informed the community’s relationship with the land and with one another . the arrival of europeans and the subsequent fur trade brought about changes in these relationships without disturbing their essence . nevertheless , the second half of the 20th century initiated a marked interference from the part of governmental institutions into all aspects of community life . children were taken away to residential schools and the community was disbanded and displaced to make way for a planned hydroelectric project . throughout this adversity , nemaskau eenouch have persevered . they have built a community and preserved their way of life .

the nemaskau eenouch have since time immemorial maintained a harmonious relationship with the creator , his creation and his provisions , in and around nemaskau sagaheegan ( nemaska lake ) , lake where the fish are plentiful . it is by the lake that they are called or call themselves the nemaskau eenouch , people from the place of plentiful fish .

the nemaskau eenouch lived , fished , hunted and trapped in the area peacefully without much contact with the outside world . during their annual summer gathering at nemaskau sagaheegan the people would catch , smoke and preserve the numerous species of fish , which were very abundant on the lake , especially sturgeon and whitefish .

prior to the arrival of european fur traders and missionaries there is not much that is known of the history of the nemaskau eenouch but there is evidence of their presence on the lake which could date back to certain millennia , these being the petroglyphs or “rock art / paintings” found on a rock faces , on or near the lake . during the iroquois wars , there were frequent visits by war parties and the iroquois built a fort on an island on nemaska lake , the location has not yet been found but was mentioned in the journals of father charles albanel .

for over three hundred recorded years the nemaskau eenouch have had a settlement of some sort on the shores of nemaska lake . european fur traders first reached the settlement around 1663 . father charles albanel , a jesuit priest , as recorded in his journal , arrived on nemiskau lake on june 25 , 1672 . the hudson’s bay company , the northwest company and reveillon et freres all had a trading post at one time or another either at the old settlement or on some other area of the lake . the hudson’s bay company made numerous attempts at having a post at old nemaska and eventually in 1906 / 07 built more permanent facilities , consisting of a residence , warehouse and store and which after many years were finally abandoned and closed in 1970 . prior to any housing of any form being built the people lived in various forms of temporary dwellings , with the first houses in the 1950’s and 1960’s being provided by the department of indian affairs , mostly with local materials with some lumber brought in by plane .

the anglican church built a church at the old post in the late 1940’s with a local “catechist” whose father and grandfather had served the anglican church and the community . in the 1950’s the department of indian affairs built a “summer day school” and a teacher’s residence , for school age children , which served as an introduction to “institutionalized” education . in the late 1950’s or early 1960’s reverend dale and josephine tozer family set up a “baptist” mission , and upon their departure were succeeded by reverend larry and peggy linton , who remained at old nemaska until the relocation .

during the 1950’s and 1960’s hydro - quebec made frequent forays into the nemaskau eenouch traditional and ancestral territory for the purposes of gathering technical information to support the feasibility and development of the nottaway / broadback / rupert hydro - electric projector , commonly referred to as the nbr project . part of the information gathering forays were for outlining , identification and early neutralization of potential problems . one major identifiable potential problem was the settlement on nemaska lake and the nemaskau eenouch who lived there . if the project were to be a reality the settlement would be under water , therefore the residents would have to be removed or relocated .

in the summer of 1968 , the nemaskau eenouch received a visit from either a representative of the government of quebec , government of canada or hydro - quebec and were told that they had to move out of their community , and warned that their community would be flooded by a large - scale hydroelectric project , and that only the hudson’s bay company facilities , the church steeple and the graveyard would be above water .

the hudson bay company , which had for so many years provided materials , supplies and non - traditional foods was finally closing its services which further “persuaded” the people to “abandon” their centuries’ old settlement , in 1970 . it was during this same summer nemaskau eenouch under duress moved from their original and ancestral home on the shores of nemaska lake , where their ancestors since time immemorial practiced , maintained and survived through the traditional way of life and harmonious relationship and connection with the lake . they were relocated to the communities of mistissini and waskaganish .

after seven ( 7 ) years of “exile” , in september 1977 , the nemaskau eenouch decided to gather at doethawagan ( champion lake ) , near their original settlement . with the help of the grand council of the crees ( eeyou istchee ) the community members , considered , discussed and evaluated their situation . approximately ninety - five ( 95 ) members were present . the nemaskau eenouch at had a choice whether to attempt “assimilating” into their respective communities of relocation or they could start over .

according to the james bay and northern quebec agreement they could resettle “within the vicinity of nemaska lake” . if they choose to resettle within the area they were given by government officials three ( 3 ) choices for the location of their new community , they choose none . the nemaskau elders had made a recommendation for the site and the nemaskau eenouch chose the site recommended by the elders . the decision to listen to the elders has proven itself , beyond a doubt , fruitful and wise over the past twenty - eight ( 28 ) years . the new village has been threatened on three ( 3 ) separate occasions by out of control , raging forest fires and each time the new community has remained unscathed although the people had to be evacuated .

in 1976 , 147 band members formally pledged themselves to permanently relocate on lake champion . the band administration was composed of one chief and two councillors and the annual budget provided by indian affairs was $ 12 , 000 . in 1980 housing construction began . the community church was the first building to be completed and an access road linking the community to the hydro quebec gravel road ‘58’ was completed allowing residents to properly commute for the first time .

the nemaskau eenouch have turned a forest into a vibrant and wholesome modern community . links to the previous settlement on nemaska lake are strongly maintained . the area was declared a historic site by the nemaska community and has been recognized as such by the cree nation . the reconstruction of family houses as they were in 1960s has been under way for the past couple of years .

every summer nemaska holds a traditional gathering every summer at nemaska lake . the journey of the nemaskau eenouch has only just begun… .

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the plane , a dash - 8 , was not in the process of landing or taking off during the incident , but was being moved to a hangar .

no passengers were on board and the two crew members operating the plane didn’t suffer any injuries .

the incident is not affecting airport operations , an aéroports de montréal spokesperson said . the airplane was being towed back on to the taxiway early monday morning .

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to see details about aircraft , click on to the number in the appropriate column in the table below .

* must be legally entitled to work in canada . * must be a canadian citizen or permanent resident of canada . * must hold canadian professional pilot licences and medical . * must speak english and french or english and cree

mr . ernest sutherland , director of flight operations mr . ivan faust , chief pilot

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the airline was established in 1963 by bush pilot otto john hegland and started operations in july 1963 from its base at big trout lake , ontario ( but was named after bearskin lake where hegland had a general store ) . it started out by providing only charter services to the remote first nations reserves in northern ontario , using bush planes equipped with floats in the summer and skis in the winter . in 1977 , it began its first regular scheduled flights between big trout lake and sioux lookout . [ 3 ]

from then on , other scheduled flights were progressively added , first to thunder bay , followed by kenora and winnipeg . this was also the period when the government of ontario began constructing new airfields that would make the northern communities accessible year - round . therefore , in the late 1970s to the early 1980s , bearskin made the transition of bush planes to wheeled commuter planes . [ 3 ]

following the collapse of norontair in 1996 , bearskin picked up over two thirds of that carrier ' s routes , thereby adding scheduled service to all the major northern ontario cities . three years later , it expanded operations to destinations in northern manitoba . in 2003 , it sold its routes and assets servicing northern first nations communities to wasaya airways . this marked as a break with its bush flying background to focus on becoming a regional carrier . [ 3 ]

as of april 1 , 2014 , all service at region of waterloo airport ( ykf ) and ottawa airport ( yow ) was cancelled , affecting seven routes and significantly decreased the flight operations . the company indicated that a softening mining sector and high tech sectors ( such as blackberry ) were to blame for cutting the routes . additional factors included the introduction of new competitors ( such as porter airlines ) . [ 4 ] the company indicated it ' s refocusing on northwestern and northeastern routes in northern ontario . [ 5 ] [ 6 ] [ 7 ] [ 8 ]

" bearskin drops flights to ottawa , k - w " . northern ontario business

" bearskin airlines cancels all trips between waterloo region and ottawa " . cbc news

" bearskin airlines terminates service to ottawa and kitchener / waterloo " ( press release ) . sioux lookout , ontario , canada : bearskin airlines

ctv kitchener ( 25 march 2014 ) . " bearskin airlines ending service from waterloo region to ottawa " . ctv news

" aviation investigation a13c0150 bearskin airlines flight 311 " . transportation safety board of canada

" engine power loss blamed for 2013 bearskin crash " . northern ontario business . 2015 - 04 - 15

december 4 , 1997 : flight 310 , a beechcraft 99 hit the runway at webequie airport when it descended too quickly . no injuries were reported . [ 13 ]

november 10 , 2013 : a swearingen metroliner crashed on approach into red lake airport in ontario after a flight from sioux lookout airport , killing five of seven people aboard . [ 15 ] [ 16 ] the crash occurred south of the airfield where the aircraft struck trees and a power line before being destroyed by impact and fire . [ 17 ] the transportation safety board of canada concluded that there was a total failure of the left engine about 500 feet above ground due to an internal component . this slowed the aircraft and caused it to stall . this led honeywell , the engine manufacturer , to issue a change to inspection procedures for fuel nozzles . [ 18 ]

dryden , fort frances , kapuskasing , kenora , north bay , red lake , sault ste . marie , sioux lookout , sudbury , timmins , winnipeg

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prior to becoming mayor , emanuel served as the white house chief of staff to president barack obama and served three terms in the u . s . house of representatives representing chicago’s 5th district . he previously served as a key member of the clinton administration from 1993 to 1998 , rising to serve as senior advisor to the president for policy and strategy .

mayor emanuel graduated from sarah lawrence college in 1981 and received a master ' s degree in speech and communication from northwestern university in 1985 .

his excellency the right honourable david johnston , c . c . , c . m . m . , c . o . m . , c . d . , governor general and commander - in - chief of canada

david johnston began his professional career as an assistant professor in the faculty of law at queen’s university in 1966 , moving to the university of toronto’s faculty of law in 1968 . he became dean of the faculty of law at the university of western ontario in 1974 . in 1979 , he was named principal and vice - chancellor of mcgill university , and in july 1994 , he returned to teaching as a full - time professor in the mcgill faculty of law . in june 1999 , he became the fifth president of the university of waterloo .

mr . johnston has served on many provincial and federal task forces and committees , and has also served on the boards of a number of public companies . he was president of the association of universities and colleges of canada and of the conférence des recteurs et des principaux des universités du québec . he was the founding chair of the national round table on the environment and the economy and chaired the federal government’s information highway advisory council .

his academic specializations include securities regulation , information technology and corporate law . mr . johnston holds an ll . b . from queen’s university ( 1966 ) ; an ll . b . from the university of cambridge ( 1965 ) ; and an ab from harvard university ( 1963 ) . while at harvard , he was twice selected for the all - american hockey team and was named to harvard’s athletic hall of fame . he was the first non - american to chair harvard’s board of overseers .

he is the author or co - author of 24 books including new editions , holds honorary doctorates from over 20 universities and is a companion of the order of canada . he was born in sudbury , ontario , and is married to sharon johnston . they have five daughters and 11 grandchildren .

sworn in on october 1 , 2010 , his excellency the right honourable david johnston is the 28th governor general since confederation .

bruce rauner ( republican ) was sworn in as the 42nd governor of illinois on jan . 12 , 2015 .

his goal as governor is to create a more prosperous state , where everyone has an opportunity to succeed .

bruce will remain focused on delivering value for taxpayers , creating a pro - jobs economic climate , ensuring world - class schools and educational options for every illinoisan , and bringing term limits and greater accountability to state government . bruce was born in illinois and is a self - made businessman who had no inheritance or family wealth .

a dedicated and diligent student , bruce worked while he attended dartmouth college , where he graduated with top honors . he went on to earn an m . b . a . from harvard .

returning to illinois in 1981 , bruce began working at then startup investment company golder , thoma , cressey ( later gtcr ) . as one of its earliest partners , bruce helped build the firm into one of the most successful and respected businesses in illinois .

gtcr has been trusted for decades to oversee the retirement investments of first responders , teachers and other illinois workers and has created tremendous returns for them – far surpassing the stock market’s performance – providing exceptional value for taxpayers .

bruce has reinvested much of his success into the state he loves through supporting education , the ymca , local hospitals and community organizations . his greatest passion is education . bruce and his wife , diana , have devoted a tremendous amount of their personal time and resources to improving education throughout the state .

bruce has never let his success change him . he still drives a 20 - year - old camper van , wears an $ 18 watch , and stays in the cheapest hotel room he can find when he’s on the road . he is the proud father of six children – two boys and four girls – and diana is the love of his life . he hunts birds , hikes , loves riding his harley , and jumps at every opportunity to fish .

bruce heyman presented his letter of credence to the governor general of canada on april 8 , 2014 , having been confirmed as president obama ' s personal representative to canada on march 12 , 2014 , and having been sworn in on march 26 , 2014 . he is a 33 year veteran of goldman sachs , where he served as a regional managing director of the midwest private wealth management group , which covers 13 states and half of canada , from 1999 until december of 2013 .

mr . heyman has served as a board member for the chicago council on global affairs and the northwestern memorial hospital foundation . he also served as an advisor to the fix the debt ceo council of the committee for a responsible federal budget . he has been a member of the economic club of chicago , the executives ' club of chicago , and the facing history and ourselves chicago advisory board .

a magna cum laude graduate with both a ba and an mba from vanderbilt university , mr . heyman continues to maintain close ties to his alma mater . he is past president of the alumni board and a former member of the board of visitors at the university ' s owen graduate school of management .

the great lakes - st . lawrence region : our bi - national gateway to north

in october , 2009 , gary doer assumed his responsibilities as canada’s 23rd to the united states of america .

prior to taking up his current position in washington , ambassador doer served as premier of manitoba for ten years . during that time , he worked extensively with u . s . governors to enhance canada - u . s . cooperation on trade , agriculture , water protection , climate change and renewable energy .

ambassador doer won three consecutive elections as premier of manitoba with successive increased majorities . in 2005 , he was named by business week magazine as one of the top 20 international leaders on climate change . his government introduced balanced budgets during each of his ten years in office while reducing many taxes , including a plan to eliminate small business tax . as premier , he led strategic investments in health care , education , and training and infrastructure .

betty sutton was sworn in as the tenth administrator of the saint lawrence seaway development corporation ( slsdc ) on august 13 , 2013 . as administrator , ms . sutton leads the u . s . federal government agency that partners with the canadian st . lawrence seaway management corporation to operate and maintain the locks and vessel traffic control areas in the st . lawrence seaway . in addition , the slsdc performs trade development functions designed to enhance great lakes st . lawrence seaway system utilization .

the youngest of six children , betty sutton is the daughter of a library clerk and a boilermaker . she attended public schools and earned a bachelor’s degree in political science at kent state university in 1985 , and a law degree at the university of akron school of law in 1990 . her law school achievements included both the federal bar association and american jurisprudence awards for excellence in constitutional law .

ms . sutton commenced her career in public service while still in law school , running for and winning an at - large seat on the barberton city council in 1990 . a year later , she was appointed to an at - large seat on the summit county council and served until 1992 , including service as the council’s elected vice president . that same year , she became the youngest woman ever to win election to the ohio house of representatives , where she served for eight years until term limits prevented her from seeking re - election in 2000 .

leaving public service , ms . sutton worked as a labor attorney with the cleveland firm of faulkner , muskovitz & phillips from 2001 to 2006 , where she represented workers , including first responders , teachers , and members of the international longshoremen’s association ( ila ) , the union that represents dock workers throughout the great lakes seaway system .

in 2006 , ms . sutton ran for and won a seat representing ohio’s 13th congressional district , winning re - election in 2008 and 2010 . while in congress , ms . sutton successfully sponsored and passed a number of measures , including the effective and popular “cash for clunkers” program , which was responsible for creating and saving 60 , 000 u . s . auto industry jobs .

ms . sutton was elected president of her congressional class , earned a seat on the house energy and commerce committee in her second term , and was chosen to co - chair the congressional jobs task force . she is the recipient of many awards , including legislator of the year awards from the great lakes maritime task force , ohio amvets , the national urban league , and was named an automotive all star by automotive news .

douglas porter has over 25 years of experience analyzing global economies and financial markets . as chief economist at bmo financial group , he oversees the macroeconomic and financial market forecasts and co - authors the firm’s weekly flagship publication , focus . mr . porter manages the team that won the prestigious lawrence klein award for forecast accuracy of the u . s . economy , and was named by bloomberg as top canadian forecaster .

as a respected commentator on economic and financial trends , he is regularly quoted in the national press and often interviewed on radio and television .


laser diffraction analysis , also known as laser diffraction spectroscopy , is a technology that utilizes diffraction patterns of a laser beam passed through any object ranging from nanometers to millimeters in size to quickly measure geometrical dimensions of a particle .

this process does not depend on volumetric flow rate , the amount of particles that passes through a surface over time .

laser diffraction analysis

laser diffraction analysis <EOT> ian treviranus , product line manager for horiba scientific ( urltoken ) , discusses fundamental principles and practical considerations of laser diffraction for particle size analysis .

within our laser diffraction systems the primary physical diffraction set - up is realised deploying a parallel laser beam . this yields the purest optical alignment for analysis of extended special arrangements of particle collectives which allows for size characterization beyond limiting assumptions and constraint .

konert m , vandenberghe jef ( 1997 ) comparison of laser grain size analysis with pipette and sieve analysis : a solution for the underestimation of the clay fraction . sedimentology 44 : 523–535 .

laser diffraction is so popularly and extensively used because it offers a number of advantages . these advantages include :

laser diffraction uses mie theory of light scattering to calculate the particle size distribution , assuming a volume equivalent sphere model .

laser diffraction is an important technique for measuring particle size . here we offer a range of facts about this technique :

the helium gas in the laser tube provides the pumping medium to attain the necessary population inversion for laser action .

eshel g , levy gj , mingelgrin u , singer mj ( 2004 ) critical evaluation of the use of laser diffraction for particle - size distribution analysis . soil sci soc am j 68 : 736–743 .

pieri l , bittelli m , pisa pr ( 2006 ) laser diffraction , transmission electron microscopy and image analysis to evaluate a bimodal gaussian model for particle size distribution in soils . geoderma . 135 : 118–132 .

a sophisticated method for determining particle size , laser diffraction is widely used and offers distinct advantages that are beneficial for many industries .

. today , laser diffraction analyzers go beyond simple diffraction effects . general approaches are now based on the mie theory and the measurement of scattering intensity over a wide scattering angular range is employed . additionally , non - laser light sources are often used to complement the main laser source to gain additional characteristic information about submicron - size particles .

diffraction is also known as " edge diffraction " as that is where it occurs . refraction occurs as light changes angle traveling throught the particle .

. . . two types of international standard methods for laser diffraction have established in dry and wet forms ( iso 13320 - 1 , 1999 ) . a manufacturer of laser diffraction also recommends users select the appropriate dispersion method between dry and wet dispersion analysis ( kippax , 2005 ) . one of the key points for laser diffraction particle sizing is that it is important to present well dispersed particles , which should be introduced to the sample cell at a suitable concentration with minimal sample bias . . . .

isotope analysis can help you identify important relationships between hydrocarbons and their sources . we offer high - precision isotopic analysis of oils , gases , kerogens , waters , and a variety of other liquids .

miller ba , schaetzl rj ( 2012 ) precision of soil particle size analysis using laser diffractometry . soil science society of america journal . 76 ( 5 ) : 1719–1727 .

by laser diffraction analysis it is possible to measure particles sizes between 0 . 02 and 2000 µm . the sample is dispersed in either air or a suitable liquid media . the laser passes through the dispersion media and is diffracted by the particles . the diffraction light pattern ( he - ne laser ) is dependent on the particle size . the laser diffraction pattern is measured and correlated to the particle size distribution based on fraunhofer or mie theory . the use of mie theory presupposes knowledge of the light refractive index of the particles and the dispersion media and the imaginary part of the refractive index of the particles . particle analytical can determine these refractive index parameters .

understanding the basic principles of laser diffraction is essential for successful method development . laser diffraction is an ensemble particle - sizing technique , which means it provides a result for the whole sample , rather than building up distributions from data for individual particles , in the way that , for example , image analysis or microscopy does . particles illuminated in a collimated laser - beam scatter light over a range of angles . large particles generate a high scattering intensity at relatively narrow angles to the incident beam , while smaller particles produce a lower intensity signal but at much wider angles . using an array of detectors , laser - diffraction analyzers record the pattern of scattered light produced by the sample .

laser diffraction is a widely used particle sizing technique for materials ranging from hundreds of nanometers up to several millimeters in size . the main reasons for its success are :

find the best system configuration for particle size distribution and particle shape analysis according to your laboratory or process application .

gee gw , bauder jw ( 1979 ) particle - size analysis by hydrometer - simplified method for routine textural analysis and a sensitivity test of measurement parameters . soil sci soc am j . 43 ( 5 ) : 1004–1007 .

method development involves addressing the wider set of practical issues that flow from this underlying explanation of the basic principles of operation . united states pharmacopeia ( usp ) general chapter < 429 > states that laser diffraction involves the measurement of " a representative sample , dispersed at an adequate concentration in a suitable liquid or gas " ( 2 ) . this statement neatly highlights three crucial aspects of laser - diffraction analysis : sampling , dispersion , and measurement conditions .

laser diffraction is used for determination of particle size distribution . determination of particle size distribution and understanding how it affects your products and processes can be critical to the success of drug development , as it has large impact on reactivity , dissolution rate , flowability etc . the particle size distribution measured by laser diffraction can further be used for :

wang wp , liu jl , zhang jb , li xp , cheng yn , xin ww , et al . ( 2013 ) evaluation of laser diffraction analysis of particle size distribution of typical soils in china and comparison with the sieve - pipette method . soil sci 178 : 194–204 .

sample measured – this technique allows for the whole of the sample to be measured . as the sample passes through the laser beam , diffraction is measured for all particles .

ryzak m , bieganowski a ( 2011 ) methodological aspects of determining soil particle - size distribution using the laser diffraction method . j plant nutr soil sci . 174 : 624–633 .

the carbon dioxide laser finds many applications in industry , particularly for welding and cutting .

our express lab services provide rapid processing of cuttings samples for source - rock analysis ( sra ) , x - ray diffraction ( xrd ) , and x - ray fluorescence ( xrf ) to quantify key formation characteristics .

was larger when many bins had small differences , as in the ldm analysis which provided a psd with 117 bins . the

articles have been published that purport to demonstrate the difficulties and problems of laser diffraction without any mention that these apparent issues are inherent in all particle sizing techniques . further , no reference has been made to the advantages that laser diffraction offers in terms of repeatability , ease of verification and speed of measurement . this article sets out to redress . . . [ show full abstract ]

the proven helos laser diffraction series offers a powerful technology for particle size analysis of powders , granules , suspensions , emulsions , sprays and other particulate systems from below 0 . 1 µm to 8 , 750 µm . a great variety of dispersing and dosing units provides a flexible adaptation to myriads of industrial and research applications .

the method is founded on the fact that the angle of diffraction is inversely proportional to particle size .

the most common and inexpensive gas laser , the helium - neon laser is usually constructed to operate in the red at 632 . 8 nm . it can also be constructed to produce laser action in the green at 543 . 5 nm and in the infrared at 1523 nm .

gee gw , bauder jw ( 1986 ) particle - size analysis . in : klute a . ( ed . ) methods of soil analysis , part 1 . 2nd edn . agron . monogr . 9 . asa and sssa , madison , wi , pp 383–411 .

the la - 300 uses mie scattering ( laser diffraction ) to measure particle size of suspensions . the speed and ease - of - use of this technique makes it the most popular for many applications .

the la - 960 particle size analyzer represents the tenth generation laser diffraction instrument designed by horiba . hundreds of refinements to the basic design have been included to improve performance and usability . these refinements include :

bah ar , kravchuk o , kirchhof g ( 2009 ) fitting performance of particle - size distribution models on data derived by conventional and laser diffraction techniques . soil sci soc am j 73 : 1101–1107 .

laser diffraction measurements capture information about particle size distribution by measuring scattering intensity as a function of the scattering angle , wavelength and polarization of light based on applicable scattering models . this is an absolute method that doesn’t require calibration . laser diffraction offers a number of advantages , including ease - of - use , fast operation , high reproducibility and broad dynamic size range—spanning almost five orders of magnitude , from nanometers to millimeters .

at the very heart of the laser diffraction technique is the relationship between light and surfaces ( which can be freely interchanged with " particle " for our purposes ) . when light strikes a surface it is either

our full range of sampling and analysis services can help you address your challenges in conventional , unconventional , deepwater , and other types of plays .

. . . traditionally , and quite commonly still today , the determination of the product quality is carried out by off - line measurement after the process . various techniques , such as sieve analysis ( 26 ) , laser diffraction ( 27 , 28 ) , and image analysis ( 29 ) ( 30 ) ( 31 ) , are available for off - line particle size distribution measurement . recently , also spatial filtering technique ( sft ) has been utilized for particle size determination ( 32 ) . . . .

. . . if these properties were less easy to determine , it is unlikely that laser diffraction would ever have achieved such widespread application in the pharmaceutical industry , and the incorrect selection of optical properties is largely inexcusable . it should , however , be noted that the use of incorrect optical properties could never account for some of the large differences reported between laser diffraction and other techniques ( as much as two to three orders of magnitude in some cases [ 2 ] ) . the errors observed are much more likely to be a result of poor sample preparation or the incorrect selection of the range lens within the laser - diffraction system . . . .

the la - 960 uses mie scattering ( laser diffraction ) to measure particle size of suspensions or dry powders . the speed and ease - of - use of this technique makes it the popular choice for most applications .

dry powders – even dry powders can be measured through the technique of laser diffraction . although this may result in a poorer level of dispersion than if a liquid dispersing medium was used , it is an advance that dry powders can be directly measured . in combination with a suspension analysis , it can support the assessment of the amount of agglomerated material in a dry state .

over the past two decades , laser diffraction has replaced conventional methods , such as sieving and sedimentation to size particles smaller than a few millimeters , and has replaced optical and electron microscopy for larger particles ( > 50 µm ) .

we develop , manufacture , sell and support an innovative range of best instruments for particle size and shape analysis in laboratory and process applications for customers worldwide .

the proven helos series – with its classical laser diffraction set - up deploying a parallel beam – offers a powerful technology for particle size analysis of powders , granules , suspensions , emulsions , sprays and numerous other disperse systems from below 0 . 1 µm to 8 , 750 µm . a great variety of dispersing and dosing units provides a flexible adaptation to myriads of industrial and research applications .

] is widely used in studies involving forecasting of biotic populations and system reliability analysis . when used to depict soil psd , the model is modified as follows :

sławinski c , walczak tr , skierucha w ( 2006 ) error analysis of water conductivity coefficient measurement by instantaneous profiles method . int agrophys . 20 : 55–61 .

as a technique of particle size analysis , laser diffraction is widely used and has many advantages . it offers a high level of precision , a fast speed of response , high potential for the repetition of results and a wide measurable particle diameter range . particle size analysers offer a sophisticated way of measuring particle size and enable incredible insight and understanding of the particles that make up materials used in a range of industries .

the instrument consists of a laser ( as a source of coherent intense light that has a fixed wavelength ) , a detector ( typically an array of photo sensitive silicon diodes ) and a means of passing the sample through a laser beam .

laser diffraction measures particle size distributions by measuring the angular variation in intensity of light scattered as a laser beam passes through a dispersed particulate sample . large particles scatter light at small angles relative to the laser beam and small particles scatter light at large angles , as illustrated below . the angular scattering intensity data is then analyzed to calculate the size of the particles responsible for creating the scattering pattern , using the mie theory of light scattering . the particle size is reported as a volume equivalent sphere diameter .

flexibility – laser diffraction offers new possibilities for measuring materials . it is even possible to measure the paint that is sprayed from a nozzle in a paint booth . the pharmaceutical and agricultural industries are two of the many industries that have benefited greatly from such advances .

citation : weipeng w , jianli l , bingzi z , jiabao z , xiaopeng l , yifan y ( 2015 ) critical evaluation of particle size distribution models using soil data obtained with a laser diffraction method . plos one 10 ( 4 ) : e0125048 . urltoken

the carbon dioxide gas laser is capable of continuous output powers above 10 kilowatts . it is also capable of extremely high power pulse operation . it exhibits laser action at several infrared frequencies but none in the visible . operating in a manner similar to the helium - neon laser , it employs an electric discharge for pumping , using a percentage of nitrogen gas as a pumping gas .

our global network of industry - leading laboratories is staffed with knowledgeable engineering and geoscience professionals to provide a comprehensive evaluation of your reservoir rock and fluids . services include routine and special core analysis ; geochemical analysis of rock and fluid samples ; geomechanics studies ; and evaluations to support the development of any asset , from conventional to unconventional , heavy oil , and deepwater resources .

it is well known that laser diffraction systems provide rapid , accurate , and precise measurement of particle size distributions for a wide range of applications . however , optimum results depend on the development of sops that take into account the method of sample collection and dispersion within the instrument .

the microtrac s3500 is the first particle size analyzer that uses three precisely placed red laser diodes to accurately characterize particles like never before . the patented tri - laser system provides accurate , reliable and repeatable particle size analysis for a diverse range of applications by utilizing the proven theory of mie compensation for spherical particles and the proprietary principle of modified mie calculations for non - spherical particles . the s3500 measures particle size from 0 . 02 to 2800 microns .

weatherford laboratories has the experience and technology to help you evaluate your sidewall cores and whole cores . our routine core analysis services include porosity , permeability , and grain density , and more .

rodos is the original by the inventor of dry dispersion . with this breakthrough innovation , sympatec has opened up dry applications to particle measurement technology – as early as 1982 . since then , it has been possible to dry measure powders , fibres and granules appropriate to the product , with both laser diffraction and dynamic image analysis . no other method of dispersing is anywhere near as powerful or achieves such an efficient as well as gentle dispersion from the submicron to millimetre range .

measurement quality is all about the analyzer itself : quality of components , engineering refinement , and a fundamental design which reflects basic principles . the core technologies are all mature , but as with many things higher quality leads to superior performance . a typical laser diffraction optical system will include :

buurman p , pape t , reijneveld ja , de jong f , van gelder e ( 2001 ) laser - diffraction and pipette - method grain sizing of dutch sediments : correlations for fine fractions of marine , fluvial , and loess samples . neth j geosci . 80 : 49–57 .

the co 2 laser is the most efficient laser , capable of operating at more than 30 % efficiency . that ' s a lot more efficient than an ordinary incandescent light bulb at producing visible light ( about 90 % of the output of a lightbulb filament is invisible ) .

so how does laser diffraction work ? at its very most basic , laser diffraction is about the relationship between particle size and the angle and intensity of scattered light . light scatters more intensely and at smaller angles off of large particles than small particles . every analyzer , from the very first commercial prototype to the state of the art la - 960 utilizes this principle . in fact , the analyzer itself does not measure particle size - - it measures the angle and intensity of light scattered from the particles in your sample . that information is then passed to an algorithm designed to use mie scattering theory which transforms the scattered light data into particle size information .

conceived and designed the experiments : ljl wwp . performed the experiments : wwp . analyzed the data : wwp yyf lxp . contributed reagents / materials / analysis tools : ljl zbz zjb . wrote the paper : wwp ljl .

mytos integrates the core particle size technologies of helos laser diffraction and rodos dry dispersion in a single robust body : a process - proven laser diffraction sensor for dry powders ranging from 0 . 25 μm to 3 , 500 μm . in combination with the sampling system twister a complete in - line integration into the processing pipe is realised . alternatively , mytos may be operated on - line either with twister , mixer , l - probes or existing sampling solutions . integrated at - line operation in automated lab environments is succeeded with vibratory feeder vibri . mytis is first choice for granules or fragile particles for a size range from 0 . 5 to 3 , 500 μm .

arriaga fj , lowery b , mays md ( 2006 ) a fast method for determining soil particle size distribution using a laser instrument . soil sci 171 : 663–674 .

light scattering has long been used to investigate the size of various objects . gustav mie ( he of the mie scattering theory ) studied gold nanoparticles like those in the image below as part of his doctoral thesis . previously confined to custom - built setups in labs , several innovations took laser diffraction from the darkroom to research labs and production floors across the world .

both the hardware and software required to make a particle size measurement have gone through many revisions in order to improve accuracy , precision , reliability , and ease of use . the la - 960 represents the tenth generation of horiba laser diffraction analyzers ; each different and better than the last . read on to discover what important factors go into making this measurement routine and trustworthy .

the laser diffraction instrument applied by particle analytical ( malvern mastersizer 2000 and 3000 ) has a flow - through cell for dispersion of particles in liquid media or a dry dispenser for dispersion of particles in air . wet dispersion presupposes that the particles are insoluble in the liquid . therefore method development is required . we typically offer either a simple non - gmp suitability screening or a full length gmp method development .

for particles smaller than 20 microns refracted light becomes increasingly important to calculate an accurate particle size . the scattered light is at relatively low intensity and wide angle for these smaller particles . the use of a refractive index and the mie scattering theory directly affects accuracy in this size range . all horiba laser diffraction analyzers use the mie scattering solution by default and allow the user to input custom refractive index values .

the argon ion laser can be operated as a continuous gas laser at about 25 different wavelengths in the visible between 408 . 9 and 686 . 1nm , but is best known for its most efficient transitions in the green at 488 nm and 514 . 5 nm . operating at much higher powers than the helium - neon gas laser , it is not uncommon to achieve 30 to 100 watts of continuous power using several transitions . this output is produced in a hot plasma and takes extremely high power , typically 9 to 12 kw , so these are large and expensive devices .

for particles larger than a certain size the vast majority of light is scattered by diffraction . the scattered light is at relatively high intensity and low angle for these larger particles . the " certain size " is determined as a multiple of the wavelength of light used for the measurement and typically approximated at 20 microns . particles larger than this size communicate useful size information through diffraction and not refraction . this means the measurement will not benefit from the use of a refractive index to accurately interpret refracted light .

funding : this study was funded by the national basic research program of china ( 973 program no . 2011cb100506 ) —ljl ; national natural science foundation of china ( contract no . 41171179 ) —ljl . the funders had no role in study design , data collection and analysis , decision to publish , or preparation of the manuscript .

a simplified layout of the la - 960 optical bench . 1 : red wavelength laser diode for larger particles , 2 : blue led for smaller particles , 3 : low angle detectors for larger particles , 4 : side and back angle detector arrays and smaller particles .

some industrial particles are non - spherical , but the scattering effects from the corners and edges of these particles are smoothed out due to the tumbling and rotational motion of sample circulation during measurement . this allows for the application of either the mie or fraunhofer theory to systems with one parameter : diameter . this method yields only apparent values , and it’s important to realize the " size " obtained from most particle sizing technologies ( laser diffraction included ) may differ from the real dimension . to date , spherical modeling is the only feasible choice for commercial instruments designed for sizing a wide range of samples , regardless of real particle shape .

in previous work , the relative performance of various methods used to characterize the particle size distribution of powders composed of fine irregularly shaped particles was assessed . it was found that methods employing fraunhofer diffraction theory were inferior with respect to particle counting methods . furthermore , calculated particle size distributions varied considerably between . . . [ show full abstract ]

helium - neon lasers are common in the introductory physics laboratories , but they can still be dangerous ! according to garmire , an unfocused 1 - mw hene laser has a brightness equal to sunshine on a clear day ( 0 . 1 watt / cm 2 ) and is just as dangerous to stare at directly .

modeling the size distribution of soil particles to obtain a continuous particle size distribution ( psd ) curves is useful for understanding essential soil properties such as pore distribution , water retention , hydraulic conductivity , and thermal and adsorption properties [ 1 – 4 ] . however , conventional psd analysis captures only a limited number of particle mass fractions . therefore , to be able to use these discrete experimental psd data to estimate other soil properties , many researchers have used parametric functions to extend the limited scope of psd data .

in this article , deborah huck , phd , product technical specialist , morphological imaging systems ; paul kippax , phd , product group manager , micrometrics ; anne virden , phd , product technical specialist , diffraction , all of malvern instruments , and janne raula , phd , senior research associate ; and professor esko kauppinen , phd , teicos pharma , inc ( espoo , finland ) , explore the value and . . . [ show full abstract ]

in the present study , ph was used to identify outliers . when a set of subsample pairs had a cbd exceeding 1 sd plus the mean cbd of all samples , the precision or repeatability of the psd results were considered insufficient for this type of analysis . in these cases , additional subsamples were measured using the same procedure as for the previous subsamples until every sample had a pair of subsamples with a cbd less than the ph , which meant that some samples had to undergo more than two analyses to obtain an eligible cbd . the samples chosen for additional measurements were only those that continued to have a cbd greater than ph . for those samples which had been measured several times , the mean of the two subsample values with the least cbd was used to represent the psd for each sample .

particle size distribution is a fundamental property of any sediment or soil , and particle size determination can provide important clues to sediment provenance . for forensic work , the particle size distribution of sometimes very small samples requires precise determination using a rapid and reliable method with a high resolution . a protocol has been developed using a coulter™ ls230 laser granulometer , which can analyse particles in the size range 0 . 04 μm–2000μm . the technique is essentially non - destructive , permitting the recovery of critical samples , and has been demonstrated to have high precision for a range of soils , sediments and powders of interest in forensic investigations .

few comparisons have been performed of the fitting performance of psd functions based on ldm data sets . furthermore , the effect of texture on psd model performance has not been fully investigated . therefore , the objectives of this study were to ( 1 ) use a variety of models with different underlying assumptions to test the fit of varying psd functions to laser - derived psd of soils from across china , and ( 2 ) to determine whether soil texture significantly affects model performance . three statistical indices were used to define the best models : the adjusted root - mean - square error ( rmse ) , the adjusted r 2 , and akaike’s information criterion ( aic ) .

aic analysis of models for soils of different clay , silt , and sand contents revealed that the performance of a psd model can be affected by soil texture . results indicated that fred3 , mlog3 , and four lognormal models ( logn2 onlg3 , orlg3 , and shca3 ) performed consistently well for all kinds of soil texture in this study ( fig 8 ) . the fred4 model had the best fit overall , accounting for most of the smallest aic values for all soils with different textures , except for sand and loamy sand soils . other studies have previously established that fred4 is highly suitable for modeling all soil texture classes [ 26 , 8 , 9 ] . the difference in the present results with fred4 , i . e . , the finding that it did not perform well for all soil classes , was probably related to the fact that the ldm underestimated the clay fraction . ande4 performed well for loam and sandy loam soils . jaky1 , logl2 , the two logistic models ( logi2 and logi3 ) , and the three van genuchten models ( vanh2 , vanz2 , and vanz3 ) showed poorer performance for most texture classes . gomp4 also performed poorly for most soil types ; however , for sand and loamy sand , it achieved the second most suitable fit with the psd data , after shca3 . logi4 seemed to be more appropriate for silty loam , clay , clay loam , loam , and silty clay loam . the performance of vang4 was only relatively better in silty loam , clay , clay loam , sand , and sandy loam soils .

dispersion describes the behaviour of clay particles separating from one other in a moist soil . dispersion can cause soil aggregates to breakdown and the dispersed clay to clog soil pores . structural decline and

clays particles are small in size ( less than 0 . 002 mm ) but have a very large surface area . the surface area of all clays is negatively charged . this is because of the complex arrangement of elements ( e . g . aluminium , oxygen , silicon ) that make up the clay structure . positive ions ( cations such as calcium , ca

) present in the soil are electrostatically attracted to the negative clay surface and neutralise the charge in the clay . as all the negative charges on the clay are neutralised , a layer of positive charge surrounds the clay particle . this layer of positive charge is also known as a ' shell ' .

cations floating around in the soil solution as salts , also affect the width of the shell . cations ' attached ' to the clay particle diffuse away from the surface of the clay until the concentration of cations is equal to the concentration of cations in the soil solution . thus , the saltier the soil solution , the thinner the layer of positive charge surrounding the clay particle .

like charges repel one another , however , this can be overcome by close distance nuclear attraction , called van der waal ' s forces . if the shell is thick , the clay particles are going to have trouble coming close enough together for the van der waals ' forces to act and for the particles to flocculate . they will tend to remain as separate ( colloidal ) entities – and the clay will be dispersed .

if the shell is thin , the particles can come close together for attractive van der waal ' s forces to take hold and for the clay particles to flocculate .

are typically highly dispersive for the reasons outline above . sodic soils have a high concentration of exchangeable na

, creating a thick layer of positive charge that may prevent clay particles from flocculating .

the cations ‘attached’ to the clay particle are exchangeable with other cations in the soil solution . which cations ‘attach’ to the clay depends on the concentration and physical size of the cations .

the following two videos illustrate dispersion when susceptible soil aggregates are immersed in water .

the video shows two aggregates of soil immersed in water . both aggregates slake on immersion . however , as time progresses the right hand aggregate disperses completely and all that remains at the 30 minute mark are a few sand grains and a cloud of clay .

the video shows an aggregate of soil resisting slaking ( although there is some release of air bubbles ) and undergoing visual clay dispersion within 30 seconds of immersion .

dispersive clays are relatively mobile within a soil . as they move they tend to clog soil pores and form layers of low permeability . surface sealing , restricted water transport and drainage , reduced macro - porosity , increased swelling , and increased soil erosion are likely outcomes .

flocculated clays tend to be stable and hence result in a relatively resilient soil structure . floccualated clays encourage soils to aggregate , and soils with stable aggregates allow water infiltration and drainage , provide pore spaces for air and water storage , provide housing for soil biology , and are more resistant to erosion .

. if your soil is sodic , soil testing to find out the concentration of exchangeable and soluble salts in your soil is needed . these numbers will provide you with the information to calculate whether treating the soil with gypsum is practical and cost effective for you .

content of your soils will also significantly improve the stability of your soil and its ability to resist dispersion when the soil is moist .

lastly , protecting the surface of your soil by maintaining ground cover will decrease the impact of raindrops and other mechanical disturbances on your soil that breakdown the soil and cause dispersion .

to assess your soil to see if it will disperse , there is a relatively quick and simply test that you can do yourself at home .

practical note : aggregate stability well aggregated soil is important . it has pores between aggregates and within the aggregate . large pores allow for the exchange of oxygen and other gases with the atmosphere , while small pores hold plant available water and dissolved nutrients .

. if your soil is sodic , soil testing to find out the concentration of exchangeable and soluble salts in your soil is needed . these numbers will provide you with the information to calculate whether treating the soil with gypsum is practicable and cost effective for you .

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mie theory requires knowledge of the optical properties ( refractive index and imaginary component ) of both the sample being measured , along with the refractive index of the dispersant . usually the optical properties of the dispersant are relatively easy to find from published data , and many modern instruments will have in - built databases that include common dispersants . for samples where the optical properties are not known , the user can either measure them or estimate them using an iterative approach based upon the goodness of fit between the modeled data and the actual data collected for the sample .

a simplified approach is to use the fraunhofer approximation , which does not require knowledge of the optical properties of the sample . this can provide accurate results for large particles . however it should be used with caution whenever working with samples which might have particles below 50µm or where the particles are relatively transparent .

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one of the excited levels of helium at 20 . 61 ev is very close to a level in neon at 20 . 66 ev , so close in fact that upon collision of a helium and a neon atom , the energy can be transferred from the helium to the neon atom .

this shows the beams from two helium - neon lasers passing through two lenses arranged in the galilean telescope geometry . the beams were made visible with a spray can of artificial smoke .

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these core principles explain much of the relationship between particle size and the angle and intensity of scattered light .

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the author examines the process of method development , with reference to iso 13320 : 2009 and relevant monographs from the united states and european pharmacopoeias .

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lactose is a white , crystalline slightly sweet tasting powder . it is a disaccharide consisting of glucose and galactose and is widely used as an excipient in the pharmaceutical industry . lactose powders are manufactured by selectively modifying the particle size , particle shape and particle size distribution of particles and they have special characteristics in terms of compactability , flow behaviour and granulability .

inspired by capsule technology , the coffee industry is constantly bringing new types of coffee onto the market that continue to stimulate consumption . this increases the requirements for quality control , particularly with respect to the particle size distribution of coffee powder . another challenge is the strong internationalisation of coffee producers , which makes comparability of analyses at different locations necessary . industrial grinding of coffee and frequent changes in variety require a consistent , partially automated control of the particle size distribution to ensure consistent product quality .

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optical setup | iso 13320 , § 5 , fig . 2 for particle size from 0 . 1 µm to approx . 3 . 0 mm

the process begins with a light source that generates a monochromatic beam . after passing through several optical components , the raw beam creates an expanded , collimated beam that illuminates particles in the scattering volume . the particles scatter light , generating unique angular scattering patterns .

these scattering patterns are transformed into a spatial intensity pattern that is detected by a multi - element photo - detector array . a photocurrent is subsequently processed and digitized , creating an intensity flux pattern that is converted into a particle size distribution .

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we can obtain information about the size of a particle using the angle and intensity of scattered light . diffracted and refracted light is useful for this purpose ; absorbed and reflected light works against this purpose and must be taken into account during measurement and size calculation .

acquiring the best possible scattered light data is the basis of any reliable size measurement . the " raw " scattered light data is then passed to the calculation algorithm where it will be transformed into a particle size distribution .

considered a standard method in many industries because of its ability to characterise particles and for reasons of quality control .

huge advances have been made in instrumentation over at least the last two decades .

an absolute method grounded in fundamental scientific principles – in this method it is not necessary for an instrument to be calibrated against a standard . however , validation of equipment is possible to prove that it is performing to a standard that can be traced .

wide and dynamic range – in measuring particle size , good equipment will allow the user to measure particles sized between approximately 0 . 1 and 2000 microns .

liquid suspensions and emulsions – it is possible to use a recirculating cell to measure liquid suspensions and emulsions . this technique promotes a high level of reproducibility and facilitates the use of dispersing agents and surfactants to determine the primary particle size . if it is possible to do so , it is preferable to take measurements in a liquid suspension .

rapid – this technique is so rapid that results can be derived in one minute or less . feedback can therefore quickly be provided to plants and repeat analyses can also be made quickly .

repeatable – this technique is highly repeatable and knowing that the results can be relied upon provides peace of mind .

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soil psd is frequently assumed to follow a lognormal distribution [ 5 , 6 ] , although some soils do have a bimodal psd [ 7 ] . buchan and hwang compared five lognormal models and certain other types of models in terms of their fit to experimental psd data [ 8 , 9 ] . their results showed that the bimodal model gave a marginally better fit , but incorporates a sub - clay mode , and the jaky model gave a good fit to data for many soils , better than the standard lognormal model for 23 soils . the latter included models based on water - retention curves [ 10 – 12 ] , the fragmentation model [ 13 ] , power - law functions based on fractal geometry [ 13 , 14 ] , exponential functions [ 15 ] , gompertz equations [ 16 ] , and a model estimating psd from limited soil texture data [ 17 ] .