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Oct 16, 2010, 06:55 PM Original Poster #1
mirajs57 mirajs57 is offline
cz
Oct 2010
4
Gold prospecting in Philippines
Is here somebody with good knowledge of Philippines? What are the best places for gold dredging, using of metal detectors, etc.
I have selected some places for visit during my vacation in February 2011 (Sibuyan, Compostella Valey, Surigao) whre some gold is. However, I accept advice from more experienced. (any good area to try metal detector?)
Reply With Quote Reply With Quote Oct 19, 2010, 01:46 PM #2
lem49 lem49 is offline
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Re: Gold prospecting in Philippines
first, I do not know of areas in the phillipines, but a heads up thats important. When traveling in certain countries
you need to be extra careful, I know that the jungles in the phillipines harbor some unsavory, anti american militant
groups. In addition, when in countries where there is extreme poverty, you need to take care, that your detector
will be a magnet for bandits.
Using your detector at a beach in a heavy tourist area may be safer, but remember there are thieves who thrive on
tourist. of course thats almost everywhere, but in countries where there is much poverty more so.
Here in Panama if they know you are an american, its like you are walking around with a sign on your head that
says ATM. I am more fortunate as my wife is Panamanian, so she knows the ropes. Panama is a great place
for vacation, detecting the tourist areas of the miles of beach.
Prospecting for gold is a different game, need to go to the interior rural areas. There is a company called Panama
adventures, and one other that advertises vacations of gold prospecting. These would be safer bets. No I do not work for them
just a retired vet, whose been around the block.
best wishes and good luck
Reply With Quote Reply With Quote Oct 19, 2010, 03:45 PM Original Poster #3
mirajs57 mirajs57 is offline
cz
Oct 2010
4
Re: Gold prospecting in Philippines
Yes, thank you for reply. Some area there are problems with rebels. Nice to know if anybody try metal detecting this country like me. I plan go there in March next year. I have a Philippine girlfriend, however she has no knowledge about gold.
Reply With Quote Reply With Quote Oct 19, 2010, 10:05 PM #4
Gold_Striker Gold_Striker is offline
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Re: Gold prospecting in Philippines
(Finding gold)
Go to this site http://www.mindat.org/loc-21930.html >find your region on the map or find your prvovince in the list below>open all the links and find the ones that say major commodities gold or trace gold.
(my opinion)
Perhaps after seeing all the sites find the ones that seem safest or easiest to get to. As far as thieves I would suppose that yes they would be concentrated in the tourist areas or in places where they would have the best chance of finding a victim. I doubt being far away from a tourist area in the jungle somewhere they will be looking. Besides I bet you can hire a guide and they would be armed and know the lay of the land well.
I don't know about militants or political issues in country.
I would look into it contact the authorities in the area look up information on the area and so on. You might find a forum from there so you can speak with other people from where ever your going. I am sure there is a group of people like you there
If you tell me exactly where you will be going I will make a map of the area you want with only gold mines on a google map.
http://www.goldminingequipment.info
(Geology)
Gold is found along or near fault lines and is also found in certain types of rock. You can download google earth and then get a geologic overlay for the area you need.
Reply With Quote Reply With Quote Oct 22, 2010, 02:02 PM Original Poster #5
mirajs57 mirajs57 is offline
cz
Oct 2010
4
Re: Gold prospecting in Philippines
Thank you for your reply.
I consider Cagayan de Oro district in Mindanao, Surigao, Sibuyan Island in Visayas. However, I can go anywhere except some hot areas in southern Mindanao or a NPA dominated areas in Bicol. The most important is that I need a proper place where gold is in suitable form. For instance, in Compostella Valley near Nabunturan the gold is dispersed in fine grain inside the rock. The panning or metal detecting is not possible. So for me is most important to look for place where the gold is in suitable sized nuggets.
Reply With Quote Reply With Quote Oct 29, 2011, 11:40 PM #6
Numinen Numinen is offline
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Re: Gold prospecting in Philippines
Late reply for you but for others Camarines Norte is good if you like to hount for some Gold in Philippines!
Quote Originally Posted by mirajs57
Is here somebody with good knowledge of Philippines? What are the best places for gold dredging, using of metal detectors, etc.
I have selected some places for visit during my vacation in February 2011 (Sibuyan, Compostella Valey, Surigao) whre some gold is. However, I accept advice from more experienced. (any good area to try metal detector?)
Reply With Quote Reply With Quote Oct 30, 2011, 07:48 AM #7
russau russau is offline
May 2005
St. Louis, missouri
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Re: Gold prospecting in Philippines
thats a nice place to go and get killed! what about the bandits/outlaws in the hills. i read about some people being kidnapped and held for ransom.
Reply With Quote Reply With Quote Nov 06, 2011, 12:26 AM #8
Numinen Numinen is offline
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Re: Gold prospecting in Philippines
Quote Originally Posted by russau
thats a nice place to go and get killed! what about the bandits/outlaws in the hills. i read about some people being kidnapped and held for ransom.
I´w yet not been kidnapped yet.
And there are always risks in life if you dont dare anything u got nothing to win as I see it!
Reply With Quote Reply With Quote Oct 08, 2012, 01:25 AM #9
juanwangy juanwangy is offline
ph
Oct 2012
2
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Good pm, does anybody know who has a, gold detector/scanner or ground penetrating device here located in Northern Mindanao? we have a site here in Mindanao that needs detecting. The place used to be a japanese barracks. we just want to make sure that we can pinpoint the exact location where we will dig.
Reply With Quote Reply With Quote Nov 03, 2013, 06:05 PM #10
dave sharky dave sharky is offline
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lem 49 i,m in the Philippines and many people here have money those groups you talked about kill Philippines all so there are many ways to make money here if your broke here your very lazy i like it here i,m from USA your right all ways good to have some one with you i find silver coins from the USA war here it said united states of America on one side and a man neeling on the other side very nice as big as a us nickel or smaller.Most people here are very friendly you have punks or bad guys any where in the world the us is full of them be good all.
Reply With Quote Reply With Quote Nov 07, 2013, 07:02 AM #11
talim talim is offline
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Nov 2013
Manila
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Davao's mains product is GOLD, so there is plenty...
I have a friend not far away from Davao that finds some but need equipment to find more, a metal detector could be a good thing for a start.
Gold in river tends to hang in the curves, good places to explore dry river curves.
There are many reports about professional mining in Philippines on the net as well.
Reply With Quote Reply With Quote Dec 19, 2013, 07:41 AM #12
erictreasure erictreasure is offline
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I have a site here in the Visayan region and we have some positive signs engraved in the rock namely ( a heart shape, an F and an arrow). Our site also has a Japanese history. A lot of treasure hunters(korean and japanese) have been visiting our lot before and were very interested. Some of the koreans dug up some bones and brought it to korea. It is in the mountains and is near a river creek. A bomb was also found beside our lot and the bomb( water barrel size) was pointing to our lot. I would want to now if you have gadgets or a scanner that would be able to see the object and its depth. If possible, may I ask for your contact number. I am willing to negotiate it with you. Thank you very much. Happy Holidays and God bless you all.
Reply With Quote Reply With Quote Dec 19, 2013, 08:55 AM #13
omnicron omnicron is offline
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Talk about opening a dead thread...10.16.2010
Reply With Quote Reply With Quote Mar 07, 2015, 02:26 AM #14
Numinen Numinen is offline
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Lets Opend it again :-)
Four killed in CamSur over small mining row
Caramoan Mayor Jun Cordial, Vice Mayor Irene Breis and Barangay Gata Captain Mercy Sueno yesterday appealed for immediate assistance from the national government after Sagip Kalikasan personnel allegedly killed four barangay folk in the gold-rich island-barangay Gata in Caramoan, Camarines Sur.
The killings took place after Sagip Kalikasan personnel were said to have harassed residents over small mining in Barangay Gata. This prompted the local folk to apply for a “minahan ng bayan permit” from the Mines and Geosciences Bureau (MGB) of the Department of Environment and Natural Resources (DENR).
While the permit was being processed, the MGB issued a temporary permit through DENR-MGB personnel Marcel Pestaño so that the residents of Gata could support their livelihood and maintain order in the area.
Because of this, the barangay residents were able to continue their small mining activities which had been their livelihood since World War II.
Irked by this development, the Camarines Sur Sagip Kalikasan personnel in Gata, Caramoan headed by Eco Tria yesterday insisted that the barangay residents should halt their mining operations.
In response, Barangay Captain Mercy Sueno presented the temporary permit of the barangay residents and asked the Sagip Kalikasan personnel to present documents that would prove their presence in the was legal.
Tria asserted that they were there under the orders of Gov. Luis Miguel Villafuerte. He presented a document which showed that the Sagip Kalikasan personnel were allowed to conduct a checkpoint.
The lady barangay captain questioned the document by saying that it does not apply in the island barangay since checkpoints are conducted on roads.
Tria asked the barangay residents to wait as he would confer with “higher” officials.
Tria left the barangay but returned with about 20 Sagip Kalikasan personnel. They allegedly pointed their guns at the barangay residents engaged in mining.
When the barangay residents felt they had no choice but to fight, the Sagip Kalikasan personnel allegedly opened fire, instantly killing four residents, with one victim hit in the eye.
This prompted the municipal officials headed by Mayor Constantino Cordial and Vice Mayor Irene Breis to reiterate their request for the national government to intervene.
Municipal officials of Caramoan question the presence and illegal activities of the provincial government’s Sagip Kalikasan in the island which conducts its own gold-mining activities.
Four killed in CamSur over small mining row
4 deaths expose gold mining in Caramoan | Bicol Mail
Environment men tagged in miners? slay | Inquirer News
Be avere of the guys the guvenour Villa fuerte has in this area nighter thy or their boss is among the friendliest or most trustworthiest in in Cam Sur
Dispite this I would say the area is defenitly intresting for anyone who likes a good alluvial gold adventure.
Last edited by Numinen; Mar 07, 2015 at 02:32 AM.
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If these acids are not balanced, the inflammation will increase due to the production of cytokines produced by the cellular membranes. The ratio of omega 6 and omega 3 fatty acids in the western diet is 30:1. This diet is extremely high on omega 6 fatty acids and this is really concerning. This type of diet increases the weight and the risk of diabetes and heart diseases. Increasing the intake of processed foods increases the risk of cancer, diabetes, obesity and heart disease. The only way to lower the risk of developing some of these diseases is to change the diet and start consuming more natural foods. In order to improve the overall health and to reduce and eliminate inflammation the main thing to do is to avoid processed foods and consume home cooked meals with plenty of natural ingredients, vegetables and fruits. EART SURGEON REVEALS THE REAL CAUSE OF HEART DISEASE! Health Tips
For decades doctors and surgeons have claimed that high cholesterol is the cause of heart diseases. All this time, high cholesterols was treated with medications for reducing the levels of cholesterol and with diet based on low fat intake. But, scientists have recently discovered that heart disease is not caused by high cholesterol levels. The real cause is something way different from cholesterol.
This recent research showed that the real reason for heart disease is arterial inflammation. This discovery shook up the medical community. The dietary recommendations have created even bigger problems because they resulted in a worldwide epidemic of diabetes and obesity. The statistics show that in the USA only, ¼ of the adult population takes medications for lowering the cholesterol or statins. The same data also show that in the USA 75 million citizens suffer from heart disease and 20 million from diabetes. Each year the number of young patients suffering from heart disease is rising and this is clearly showing that cholesterol is not the reason for this type of diseases.
The real cause is the inflammation. The inflammation is actually very beneficial because it`s the natural reaction of the body to invaders. Since we are constantly exposed to toxins the body is not able to fight and process all the foreign invaders and the inflammation becomes chronic. This condition has direct consequences to the health and heart.
Unfortunately, we are the ones causing the chronic inflammation with the unhealthy lifestyle and unhealthy diet. The constant consumption of inflammatory products and foods rich in fat and sugar is harmful for the health. This type of diet leads to development of chronic inflammation and different diseases like diabetes and heart diseases. Another factor for the increased numbers of heart disease patients is the low fat diet which is highly recommended as a treatment for high cholesterol levels.
The unhealthy foods that we all consume almost daily are causing big damage to our health. It doesn’t matter where and how the inflammation is caused, what matters is that the inflammation can and will damage the health seriously. These types of foods affect the arteries and bit by bit the inflammation increases and serious medical conditions occur as a result.
The cinnamon rolls, for example, are maybe the worst food for the health. They contain high amounts of carbs and sugar which increase the risk of many medical conditions and diseases. The consumption of sweets and sugar increases the levels of sugar in the blood vary fast. This causes the pancreas to produce insulin which is a hormone that regulates the levels of glucose in the blood. This causes a chain reaction. The constant intake of sugar makes the pancreas to produce high amounts of insulin which results in high amounts of glucose which, on the other hand, gets converted into fat. The sugar molecules attach themselves to the proteins which can damage the artery walls causing increase of the inflammation and in time it can damage the blood vessels beyond repair.
The sweet rolls also contain high amounts of omega 6 fatty acids because they are usually baked in soybean oil. This type of oil contains high amounts of these acids which are used for increasing the shelf life of the products. Although omega 6 acids are beneficial, they must be in perfect balance in the body with the omega 3 acids. If these acids are not balanced, the inflammation will increase due to the production of cytokines produced by the cellular membranes.
The ratio of omega 6 and omega 3 fatty acids in the western diet is 30:1. This diet is extremely high on omega 6 fatty acids and this is really concerning. This type of diet increases the weight and the risk of diabetes and heart diseases.
Increasing the intake of processed foods increases the risk of cancer, diabetes, obesity and heart disease. The only way to lower the risk of developing some of these diseases is to change the diet and start consuming more natural foods. In order to reduce and eliminate the inflammation consume more carbs from vegetables and fruits and use olive oil or grass-fed butter instead of sunflower or soybean oils for cooking.
Animal fat or saturated fat shouldn’t be excluded from the diet because they don’t cause heart diseases. They contain low amounts of omega 6 acids, so they don’t cause inflammation. Saturated fat doesn’t affect and increase the levels of cholesterol in the blood also.
The low fat diet has caused much worse conditions. Controlling the cholesterol with this diet has increased the numbers of heart diseases patients worldwide. In order to improve the overall health and to reduce and eliminate inflammation the main thing to do is to avoid processed foods and consume home cooked meals with plenty of natural ingredients, vegetables and fruits.
Current Issue > vol. 113 no. 39 > Barbara A. Maher, 10797–10801, doi: 10.1073/pnas.1605941113
Significance
We identify the abundant presence in the human brain of magnetite nanoparticles that match precisely the high-temperature magnetite nanospheres, formed by combustion and/or friction-derived heating, which are prolific in urban, airborne particulate matter (PM). Because many of the airborne magnetite pollution particles are <200 nm in diameter, they can enter the brain directly through the olfactory nerve and by crossing the damaged olfactory unit. This discovery is important because nanoscale magnetite can respond to external magnetic fields, and is toxic to the brain, being implicated in production of damaging reactive oxygen species (ROS). Because enhanced ROS production is causally linked to neurodegenerative diseases such as Alzheimer’s disease, exposure to such airborne PM-derived magnetite nanoparticles might need to be examined as a possible hazard to human health.
Next Section
Abstract
Biologically formed nanoparticles of the strongly magnetic mineral, magnetite, were first detected in the human brain over 20 y ago [Kirschvink JL, Kobayashi-Kirschvink A, Woodford BJ (1992) Proc Natl Acad Sci USA 89(16):7683–7687]. Magnetite can have potentially large impacts on the brain due to its unique combination of redox activity, surface charge, and strongly magnetic behavior. We used magnetic analyses and electron microscopy to identify the abundant presence in the brain of magnetite nanoparticles that are consistent with high-temperature formation, suggesting, therefore, an external, not internal, source. Comprising a separate nanoparticle population from the euhedral particles ascribed to endogenous sources, these brain magnetites are often found with other transition metal nanoparticles, and they display rounded crystal morphologies and fused surface textures, reflecting crystallization upon cooling from an initially heated, iron-bearing source material. Such high-temperature magnetite nanospheres are ubiquitous and abundant in airborne particulate matter pollution. They arise as combustion-derived, iron-rich particles, often associated with other transition metal particles, which condense and/or oxidize upon airborne release. Those magnetite pollutant particles which are <∼200 nm in diameter can enter the brain directly via the olfactory bulb. Their presence proves that externally sourced iron-bearing nanoparticles, rather than their soluble compounds, can be transported directly into the brain, where they may pose hazard to human health.
brain magnetite magnetite pollution particles Alzheimer's disease combustion-derived nanoparticles airborne particulate matter
Magnetic analyses of human brain samples have identified the presence of nanoparticles of magnetite, a strongly magnetic (ferrimagnetic) mixed Fe2+/Fe3+ iron oxide (1⇓–3). Based on their nanoscale dimensions and euhedral (cubo-octahedral or prismatic) crystal shapes, these magnetite nanoparticles are thought to have formed by biological processes (1, 4), via in situ crystallization, possibly within the 8-nm-diameter cores of the iron storage protein, ferritin (e.g., ref. 5).
The specific presence of magnetite in the brain is important because it has been causally linked with potential cellular responses to external magnetic fields (e.g., in magnetic resonance imaging studies) (1), aging (6), and with neurodegenerative disease (e.g., refs. 2, 3, and 7). Previous work has shown a correlation between the amount of brain magnetite and the incidence of Alzheimer’s disease (AD) (2, 3). Neuropathological changes associated with AD include the formation of senile plaques, containing β-amyloid fibrils (e.g., refs. 8, and 9). When associated with redox-active transition metal ions, such as Fe2+ ions, β-amyloid can generate damaging reactive oxygen species, directly contributing to oxidative brain damage, a key early feature of AD (e.g., refs. 8⇓–10). Magnetite nanoparticles have been found directly associated with AD plaques and tangles (e.g., refs. 11⇓–13). In vitro experimental data show that magnetite acts synergistically to enhance the toxicity of β-amyloid (7).
We used magnetometry, high-resolution transmission electron microscopy (HRTEM), electron energy loss spectroscopy (EELS), and energy dispersive X-ray (EDX) analysis to examine the mineralogy, morphology, and composition of magnetic nanoparticles in and from the frontal cortex of 37 human brain samples, obtained from subjects who lived in Mexico City (14) (29 cases; ages 3 to 85 y; two females) and in Manchester, UK (8 cases; ages 62 to 92 y; five females; Tables S1 and S2). These brain magnetites display compelling similarity with the magnetite nanospheres formed by combustion, which are ubiquitous and prolific in urban, airborne particulate matter (PM) (15⇓⇓⇓–19). We report here identification of the presence in human brain tissue of magnetite nanoparticles with an external, rather than an endogenous, source.
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Table S1.
Summary of Mexico City cases studied
In this window In a new window
Table S2.
Summary of Manchester cases studied
Previous Section
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Results
To quantify brain magnetic content, a cryogenic magnetometer was used to measure, at room and low temperature (77 K), the saturation magnetic remanence (SIRM) of frontal tissue samples, initially fresh-frozen and subsequently freeze-dried. The SIRM 77 K captures the magnetic contribution of ferrimagnetic grains that are so small (<∼20 nm) as to be magnetically unstable (superparamagnetic) at room temperature. The magnetic brain particles were then examined directly, by HRTEM and EDX analyses both of ultrathin tissue sections and of magnetically extracted particles, after tissue digestion with the proteolytic enzyme, papain. Every analytical step was designed and monitored to preclude any possible magnetic contamination.
The brain magnetic analyses identify the presence in all of the samples of strongly magnetic, easily magnetized nanoparticles, with concentrations ranging from 0.2 to 12 µg/g dry tissue (Fig. S1). The sample magnetic properties are dominated by behavior characteristic of interacting clusters of ferrimagnetic magnetite or maghemite (Fig. S2). Although highest brain magnetite concentrations (>10 µg/g dry tissue) are seen in many of the oldest cases, several of the much younger Mexico City cases, some exposed to high ambient concentrations of fine-grained (<2.5 µm aerodynamic diameter) airborne PM, also display high ferrimagnetic concentrations. Indeed, the highest brain magnetite content is found in a 32-y-old Mexico City resident (Fig. S1).
Fig. S1.
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Fig. S1.
SIRM 77 K (10−6 A m2/kg) and estimated magnetite concentration (micrograms per gram) for frontal cortex samples versus age at death, Mexico City and Manchester cases. The annual mean airborne PM2.5 concentration (micrograms per cubic meter) is given for the residence area of the Mexican cases (inside each data symbol); SIRM values for gray (g) and white (w) matter are given for the Manchester cases, together with their clinical diagnosis upon death (CAA, cerebral amyloid angiopathy; CVD, cerebrovascular disease; DLB, dementia with Lewy bodies; see Tables S1 and S2).
Fig. S2.
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Fig. S2.
Magnetic analyses of brain tissue samples (freeze-dried): (A) acquisition of isothermal (RT) remanent magnetization in applied DC fields from 5 mT to 1 T. All samples acquire most of their magnetization at fields < 100 mT, indicating the dominant presence of ferrimagnetic minerals (e.g., magnetite and/or maghemite). The magnetically softest sample (the Mexico City case to the left of all remaining samples) has the highest SIRM value (case 282). (B) Measurement of LT remanence (77 K, DC field 1 T) upon warming to RT, showing the thermal unblocking of the superparamagnetic particles. (C) Comparison between the brain samples and sized, synthetic magnetites of known grain size and degree of dispersion (37), as measured by the RT ARM, normalized by the SIRM, plotted against the median destructive field of the ARM (MDFARM, in milliteslas). All of the measurable brain samples fall within the region of the least-dispersed synthetic, submicrometer magnetites, indicating magnetic interactions, and hence agglomeration/clustering of some of the brain magnetite particles.
HRTEM and EELS analyses of the tissue sections identify the presence within frontal cells of magnetite, occurring as two distinct types of nanoparticle (Fig. 1 and Figs. S3 and S4). The majority of particles display rounded, even spherical morphologies (Fig. 1A, with higher magnification in Fig. 1B, and Fig. 1F), with diameters between 10 and 150 nm (Fig. S5). The additional presence in the brain cells of other transition metal nanoparticles, containing Pt, Ni, and Co (and possibly Cu), is identified by EELS (Fig. S6) and EDX (Figs. S7 and S8). These rounded magnetites contrast strongly with the angular, cubo-octahedral magnetite crystals also observed (relatively very rarely) within the brain tissue samples (Fig. 1C, and with higher magnification in Fig. 1D).
Fig. 1.
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Fig. 1.
Transmission electron micrographs of brain thin sections, identifying two distinct types of magnetite morphologies within frontal cells: (A and F) rounded particles (A shown at higher magnification in B); and (C) angular, euhedral particles, which we attribute to endogenous formation (particles from C shown at higher magnification in D). (E) EELS spectra (in blue) for the rounded particle shown in F and for standard iron oxide species. The position of the Fe−L3 edge absorption peak, the broad feature of the Fe−L2 (compared with the sharp edges, arrowed, of the fully oxidized Fe3+ phases), and the integrated areas of the L3/L2 (5.5) and the Fe/O (0.56) are all consistent with magnetite (also see Figs. S3 and S4).
Fig. S3.
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Fig. S3.
(A) High-angle annular diffraction and (B) dark-field TEM micrographs showing spherical magnetic nanoparticles in brain tissues. (C) Fe−L2,3 EELS spectra of nanoparticles identified in the selected areas (boxes 1 through 4) showing the absence of any preedges (see hematite, goethite, and ferrihydrite preedge at ∼708.8 eV), Fe−L3 edges centered at 708 eV, and broad Fe−L2 features characteristic of magnetite, compared with the Fe−L2,3 EELS spectra (D) of standard magnetite, siderite, hematite, goethite, and two-line ferrihydrite.
Fig. S4.
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Fig. S4.
Fe−L2,3-edge spectra of magnetic particles found in brain samples. The Fe−L3 and Fe−L2 edges in all three samples are at 708.7 to 709.8 eV and 72 to 723 eV, in excellent agreement with the chemical shift in EELS spectra for the magnetite structure (also see Fig. S3).
Fig. S5.
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Fig. S5.
Particle size distribution of magnetic particles in brain magnetic extracts. Particle size measurements were carried out on all of the HRTEM micrographs collected from six brain magnetic extracts from different subjects. The ImageJ software package was used to describe the imaged particles (spherical and nonspherical) in terms of the longest and shortest diameters, perimeter projected area, or equivalent spherical diameter.
Fig. S6.
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Fig. S6.
(A) Co−L2,3 EELS spectra of cobalt (II, III) oxide nanoparticles associated with magnetite particles in brain tissues. Co−L3 and Co−L2 edges from different areas of a brain tissue sample (B) are centered at ∼780 and ∼796 eV, respectively, in a good match with an EELS spectrum of a standard cobalt (II,III) oxide.
Fig. S7.
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Fig. S7.
EDX analysis of metal-bearing NPs in brain tissue samples, showing presence of Fe, Ni, and Co (and possibly Cu, with the caveat that the samples were mounted on holey carbon films on Cu grids).
Fig. S8.
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Fig. S8.
EDX analysis of metal-bearing NPs in brain tissue samples, showing the presence of Fe, Ni, Pt, Co, and, possibly, Cu.
Crystallographic analysis of the particles within the tissue sections is difficult (due to rapid carbon buildup under the microscope electron beam). We therefore examined magnetically extracted (20) brain particles, to more fully characterize their mineralogy, surface textures, and particle size distribution. In accord with the observations on the untreated tissue samples, many of the extracted particles display rounded to spherical morphologies (Fig. 2 and Figs. S7–S10). In particular, some have fused surface crystallites (Fig. 2H) that would be very difficult to reconcile with low-temperature growth or dissolution formation processes. Indexing of the lattice fringes of the HRTEM of these particles is consistent with the magnetite crystal structure (Fig. 2 C, E, and G). Some surface oxidation toward its oxidized counterpart, maghemite, is evident (Fig. 2I). The particle size distribution of the rounded brain magnetite particles is notably broad, with a median (longest) diameter of 18 nm and maximum diameter of ∼150 nm (Fig. S5). Such dimensions greatly exceed those of nanoparticles formed within the 8-nm diameter of ferritin cores (5).
Fig. 2.
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Fig. 2.
Transmission electron micrographs of rounded particles magnetically extracted from human brain samples: (A, D, F, and H) Mexico City cases; (B) Manchester case. (H) A large (∼150-nm diameter) spherical particle with fused, interlocking magnetite/maghemite surface crystallites. (C, E, and G) Indexing of the lattice fringes of the brain particles is consistent with the (400) reflection of magnetite and (I) mixed magnetite and maghemite of selected areas 1–5 in H.
Fig. S9.
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Fig. S9.
(A–I) A collection of HRTEM micrographs of magnetite particles, extracted from brain tissues, showing dominant rounded morphologies. (C) Micrograph shows fused magnetite particles, and (D and E) micrographs show aggregated magnetite particles.
Fig. S10.
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Fig. S10.
(A) HRTEM micrograph of magnetically extracted magnetite particles from brain tissues. (B−D) FFT patterns of selected areas (1, 2, and 3, respectively) featuring a single crystal (B) and magnetite particles superimposed at ∼90° (C and D).
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Discussion
The geometric, angular particles resemble the in situ, biogenic magnetite previously reported (1, 4); we thus ascribe these euhedral magnetite particles to endogenous formation. The rounded magnetite nanoparticles (up to ∼150-nm diameter, with distinctive surface textures, and cooccurring with other PM-associated metals, including Pt) have not been identified previously in brain tissue sections. Apparently similar spherical structures, with diameters of 8 to 50 nm, have been found recently within amyloid plaque cores isolated from human brain (13) but were attributed to a biological rather than an external pollution-derived source. However, the surface textures, size, and size distribution of the spherical magnetites identified in our study, and the cooccurrence of PM-associated transition metal nanoparticles, are all inconsistent with the characteristics of biogenically formed magnetite (1, 4, 12). They bear compelling resemblance, instead, to the rounded/spherical magnetite nanoparticles (nanospheres) that are both ubiquitous and prolific within airborne, high-temperature (combustion-derived) PM (15⇓⇓⇓–19, 21). The rounded shapes of these airborne, PM-derived magnetites (Fig. 3 and Fig. S11), and fusing of interlocking, surface crystallites (Fig. 3 C and D), reflect their high-temperature sources, and their subsequent crystallization, upon rapid cooling and/or oxidation, as Fe-rich nanospheres. Depending on PM source(s) (vehicular, subway, industrial, indoor), other transition metals are often coassociated with magnetite and other pollution nanoparticles (15⇓–17, 19). Pt release, for instance, is associated with increasing vehicular use of catalytic converters (e.g., ref. 22). Frictional heating, e.g., of brake pads, can also produce high-temperature magnetite nanoparticles (21). Magnetite can arise from combustion of many types of organic matter, depending on heating temperature and atmosphere, and source Fe content (23⇓–25).
Fig. 3.
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Fig. 3.
TEM/scanning EM micrographs of anthropogenic (combustion-derived), magnetically extracted airborne particles. (A, shown at higher magnification in B) Magnetite nanoparticles from airborne PM (<10 µm), from Cable Street, Lancaster, United Kingdom (March 2009), sampled with a cascade impactor. Many particles display rounded profiles; some are fused together. (C and D) Spherical magnetite particles, Didcot power station, comprising fused magnetite particles (note the variable lattice orientations in C and the fused surface crystallites in D).
Fig. S11.
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Fig. S11.
TEM image of magnetite nanoparticles captured from the exhaust plume of a diesel engine. Adapted from ref. 19.
Although PM mass has conventionally been used for setting of legislative airborne PM concentration limits, it is possible that ultrafine particle size and number are of greater significance in terms of mortality (26) and health impacts (e.g., ref. 27). Our magnetic measurements of roadside airborne PM [in Lancaster, United Kingdom (28)] indicate magnetite particle numbers equivalent to ∼2.01 × 108 m−3 of roadside air, for ∼50-nm-sized magnetite particles, for an ambient PM10 concentration of ∼40 µg⋅m−3 (compared, for example, with the annual mean PM10 for Mexico City of between ∼30 and 70 µg⋅m−3).
The abundant combustion-derived magnetite particles found in airborne PM can range widely in size, from less than 5 nm to more than 1 µm (15⇓–17, 19). Those particles of nanoscale dimensions, requiring analysis by transmission rather than scanning electron microscopy, have, until recently, received less attention than the larger, often more heterogenous spherules. Magnetite nanospheres up to ≾≾ 200 nm can have a direct entry route to the brain through the axons of the olfactory nerve, as suggested by experimental studies on carbon (29) and TiO2 nanoparticles (30), and the reported presence of NPs in the olfactory bulb of some Mexico City cases (14, 31⇓–33).
Although many of the highly magnetic brain samples come from the older Manchester cases (>65 y at death), especially those with severe to moderate AD, equivalent or higher magnetite concentrations are also displayed by young (<40 y at death) Mexico City residents, especially those exposed to high PM2.5 levels (annual mean ≳≳25 µg⋅m−3). Increased metals content and AD neuropathological hallmarks have been found in young human brains exposed to high airborne PM2.5 concentrations in Mexico City (14, 33). However, it was not previously known if the presence of metals in AD brains was due to transport to the brain of nanoparticles themselves or of their solubilized compounds. Our HRTEM results provide compelling evidence for the presence of externally sourced magnetite, and other metal-bearing nanoparticles in the frontal cortex of both the Mexico City and Manchester cases. It is notable that less than 5% of AD cases are directly inherited, indicating that nongenetic (environmental) factors, and/or gene/environment interactions, are likely playing a major role in initiating and/or promoting the disease. Jung et al. (34) found a 138% risk of increase of AD per increase of 4.34 μg⋅m−3 in PM2.5 over a 9-y follow-up period in 95,690 individuals in Taiwan. It is not yet understood which PM properties (e.g., size, number, mineralogy, and associated chemical species) contribute most to toxic effects (e.g., ref. 35). Our preliminary magnetic results regarding both PM exposure and AD are thus both intriguing and warrant more intensive study. Because of their combination of ultrafine size, specific brain toxicity, and ubiquity within airborne PM, pollution-derived magnetite nanoparticles might require consideration as a possible AD risk factor. In addition to occupational settings [including, for example, exposure to printer toner powders (36)], higher concentrations of magnetite pollution nanoparticles are likely to arise in the indoor environment from open fires (25) or poorly sealed stoves used for cooking and/or heating, and in the outdoor environment from vehicle (especially diesel) and/or industrial PM sources.
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Materials and Methods
Brain Samples. Fresh, frozen brain tissues were obtained from 38 individuals (Tables S1 and S2), 9 from the Manchester Brain Bank (ethical review and approval by the Manchester Brain Bank Management Committee and the Newcastle and North Tyneside I Regional Ethics Committee) and 29 from Mexico City, from forensic cases (fatal accidents) with no identifiable personal data, not meeting the regulatory definition of human subject research (University of Montana Institutional Review Board). A block (∼25 g) of tissue was cut from the frontal lobes; subsamples were cut using nonmagnetic [polytetrafluoroethylene (PTFE)] instruments. The Manchester samples were dissected into gray (nine samples) and white (eight samples) matter.
To preclude any contamination, or operator bias, samples were handled with nonmagnetic instruments in a laminar flow clean bench environment and measured blind to diagnostics, and sample holder remanences were removed. The tissue samples were freeze-dried and placed in polystyrene sample holders (10 cc) for magnetic measurements.
Magnetic Analyses. Magnetic measurements were made at the Centre for Environmental Magnetism and Paleomagnetism, Lancaster University, using superconducting quantum interference device magnetometry. Room-temperature isothermal remanent magnetizations (IRMs) (Fig. S2A) were measured with a GM400 Cryogenic Magnetometer (mean background noise level 5.9 ×10−11 A2; Cryogenic Consultants Ltd.); Low-temperature IRMs were measured (Fig. S2B) at temperatures between 293 and 77 K (±0.5 K) on a single-axis magnetic property measurement system XL magnetometer (Quantum Design). To identify magnetic grain sizes and/or magnetic interactions (37), anhysteretic remanence (ARM) was induced in a decaying (100 mT, peak) alternating magnetic field (af), with a small superimposed direct current (DC) field (0.08 mT), and subsequently af-demagnetized (Fig. S2C). Stepwise remanence acquisition was measured with incremental application of DC fields of 10, 20, 30, 50, 75, 100, and 300 mT and 1 T. The samples were cooled to 77 K and subjected to an applied DC field, 1 T, and their remanence was measured as they warmed to room temperature.
Tissue Sections.
Magnetically extracted particles. A subset of samples (six tissue samples, and one blank without any tissue) was subjected to a magnetic extraction procedure, designed to maximize removal of submicrometer ferrimagnets (20). All reagents were prepared from ultrapurity Milli-Q water and prefiltered (<0.1 µm PTFE membrane filter) to preclude any particulate contamination; all instruments and sample holders were nonmagnetic (PTFE and polystyrene, respectively).
Papain from papaya latex (twice-crystallized; Sigma) was solubilized in 50 mM sodium acetate (prefiltered and magnetically measured multiple times to demonstrably preclude magnetic contamination). The tissue samples were digested overnight in papain at 65 °C and at fixed pH 7.0 ± 0.02, in a strictly oxygen-free environment inside a particulate-clean laboratory. The resultant suspension was circulated continuously (2 to 3 d, with a peristaltic pump) past a magnetized probe, producing a high field gradient at its tip (maximum field ∼40 mT). The magnetically extracted particles were mounted on holey carbon films on carbon-coated copper grids for transmission electron microscopy (TEM).
HRTEM, EELS, and EDX. Electron microscopy was conducted on two instruments, a JEOL ARM200cF and an FEI Tecnai F20, operated at 200 kV. A Gatan Quantum spectrometer was used for EELS in scanning TEM (STEM) mode. Due to rapid carbon buildup under the electron beam, only point acquisition spectra were collected; each spectrum typically summed from several spectra from each nanoparticle and from multiple nanoparticles. This procedure also minimized the electron dose experienced by individual nanoparticles and ensured that their chemical reduction was avoided. Time-dependent observations did not reveal any obvious structural or spectroscopic changes to the nanoparticles within the acquisition time (but were observed under prolonged exposure), and we conclude that the EELS data presented are representative of the nanoparticles' as-formed chemistry. EELS data were processed in Python using Hyperspy package. To determine dominant lattice spacings, fast Fourier transforms (FFTs) of high-resolution micrographs were compared with a simulated diffraction pattern of face-centered cubic magnetite (space group Fd3¯mFd3¯m, no. 227, a = 8.3941 Å), and maghemite (space group P4332, no. 212, a = 8.3457 Å). Sample sensitivity under STEM imaging precluded elemental mapping by EDX.
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Acknowledgments
We appreciate the reviewers’ comments, which improved our manuscript. We thank Dr. Zabeada Aslam for her technical help, Dr. Mark Taylor (University of Lancaster) and Angelica Gonzalez-Maciel (Instituto Nacional de Pediatria, Mexico City) for assistance with tissue subsampling, and the University of Leeds Engineering and Physical Sciences Research Council-funded Nanoscience and Nanotechnology Facility for access to the HRTEM. We acknowledge the support of the Manchester Brain Bank by Alzheimer’s Research UK and Alzheimer’s Society through their funding of Brains for Dementia Research initiative, and service support costs from Medical Research Council.
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Footnotes
1To whom correspondence should be addressed. Email: b.maher@lancaster.ac.uk.
Author contributions: B.A.M. designed research; B.A.M., I.A.M.A., V.K., and D.A.M. performed research; P.G.F. and D.A. contributed new reagents/analytic tools; B.A.M., I.A.M.A., V.K., D.A.M., D.M.A.M., R.T.-J., and L.C.-G. analyzed data; B.A.M. wrote the paper; D.M.A.M. provided brain tissue samples and medical diagnosis data; R.T.-J. provided airborne PM data; and L.C.-G. provided brain tissue samples.
The authors declare no conflict of interest.
This article is a PNAS Direct Submission. Y.R. is a Guest Editor invited by the Editorial Board.
This article contains supporting information online at www.pnas.org/lookup/suppl/doi:10.1073/pnas.1605941113/-/DCSupplemental.
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