（转）化学世界的十大未解之谜&（10&Unsolved&Mysteries&in&Chemistry）
1. How life began?
The moment when the first living creature
emerged from inanimate matter, nearly four billion years ago, is
still shrouded in mystery. How did the simple molecules, relatively
speaking, of the primordial soup form such complex compounds? And
how did some of these compounds started to process energy and
replicate (two characteristics of life)? At the molecular level,
all these steps are of course chemical reactions, and therefore,
the question of how life began, is a chemically question.
Chemists can not longer be
satisfied with the barely conceivable
scenarios&- and there are many of those.
Researchers have hypothesized that certain minerals, like clay, were used
as catalysts for creating the first Polymers to have
self-replication capacity (polymers, such as DNA or
are molecular chains of smaller units); or that
hydro & thermal seafloor were providing the energy that drove the
formation of chemical complexity. There are also speculate about
the “RNA world” in which RNA molecules, similar to DNA and also
works as enzymes that speed chemical reactions, were universal
molecule prior to DNA and proteins.
2. How are molecules (Molecule) created?
Molecular structures are perhaps the backbone of science classes
in high school, but the familiar scene of balls and sticks
represent the atoms and bonds connecting them is largely a myth.
The problem is that there is no consensus among scientists what is
supposed to be a more accurate representation of molecules.
In 1920 physicist Walter Baitler and Fritz London showed that
one can describe the chemical bond by quantum theory Equations, a
doctrine which was then in its infancy. Great American chemist
Linus Pauling suggested the idea that connections are created when
electronic orbitals of different atoms overlap each other in space.
Competing theory of Robert Millikan and Frederick Bond suggested
that connections are created as a result of integrating the atomic
orbitals to create “molecular orbitals” that span more than one
atom. Theoretical chemistry seemed about to become a branch of
<img ALT="" src="/blog7style/images/common/sg_trans.gif" real_src ="/readers//aa2_2.jpg" WIDTH="408" HEIGHT="437"
TITLE="（转）化学世界的十大未解之谜&（10&Unsolved&Mysteries&in&Chemistry）" /> Common tale: sticks and balls as
Almost 100 years later the molecular orbitals picture was
revealed almost completely, but still not all chemists are
convinced that in all cases this is the best way to describe
molecules. The reason is that this model of the molecules and the
like are based on simplifying assumptions and therefore are only
approximate and partial descriptions. In reality, the molecule is a
bunch of atomic nuclei surrounded by a cloud of electrons which
take place in a continuously “tug war competitions” between
opposing electric forces and the movement and reorganization of its
components. Current models of the molecule, usually trying to
freeze this dynamic entity into a static entity, and may capture
some of the most prominent thing about it, but neglecting other
Quantum theory is unable to provide a single definition of the
chemical bonds which will be consistent with the intuition of
chemists who fought to build and break these connections. Today
there are many ways to describe atoms and molecules related links.
According to the quantum chemist Dominic Marx Ruhr University in
Bochum, Germany, most descriptions “are useful in some cases but
fail in others”.
Computer simulations can now calculate&the
structure and properties of molecules from the initial quantum
principles in good precise & as long as the number of electrons is
small enough. “Using computational chemistry one can reached a very
high level of realism and complexity,” says Marx. As a result,
computer calculations can be seen as kind of a virtual experiment
with which to predict the course of a chemical reaction. However,
once the imaging engaged in response that involve more than a few
tens of electrons, the needed amount of calculations is much above
the most powerful supercomputers abilities. The challenge today is
therefore to see if we can extend these simulations and apply them,
for example, on bio-processes or on the intricate molecular
structure of sophisticated materials.
3. How does the environment affect our genes?
Biology old idea was: who we are is determined by our genes. It
is now clear that an equally important question is what genes are
we using? And just like everything else in biology, the heart of
this question is chemistry.
Cells in early embryo can develop into any type of tissue. But
as the baby grows, these cells undergo differentiation and acquire
specific roles (such as with blood, muscle or nerve), these
positions remain set in their descendants. Formation of the human
body is therefore a process in which stem cell chromosomes undergo
a chemical change or turn off complete sets of genes.
However, one of the most revolutionary discoveries in the study
of cloning and stem cells was that these changes are reversible and
are influenced by events that the body experiences. During cell
differentiation genes do not permanently paralyzed nor do they keep
in standby only genes they need. Instead, genes that were switched
off reserve a latent ability to function, i.e. retain their ability
to produce the proteins they encode, and may be reactivated, for
example following exposure to certain chemicals from the
environment.
What excited and challenged to chemists is that genes control is
probably related to chemical events of larger scale than that of
atoms and molecules, in intermediate (mesoscale), where large
molecular structures and large groups of molecules act. Chromatin,
the material that makes up chromosomes DNA and proteins, is built
in a hierarchical structure. Double helix of DNA is wrapped around
a cylindrical particle composed of proteins called histones. This
bead necklace is also a packed structures with higher order we
poorly understood. Cells maintain a tight control on this
structure. How and where a particular gene packaged within
chromatin may determine whether the gene is active or not.
Cells have specific Enzymes that determine the shape of the
chromatin. These enzymes have a central role in the process of cell
differentiation. It seems that embryonic stem cells have a more
relaxed and open structure. When certain genes are silenced, the
chromatin became more organized. “It seems chromatin is used to
fixates and preserves, or stabilizes the cells” says Bradley
Bernstein pathologist from Massachusetts General Hospital.
Moreover, the chromatin designing involve chemical modifications
of the DNA and histones. Small molecules are also used as labels
for them. They mark the cellular mechanism to silence specific
genes, or vice versa, to release them into action. This label is
called “epigenetics” because it does not change the information
carried by the genes.
It is now clear that beyond the genetic code that dictates many
important operating instructions of the cell, the cells also
converse in entirely separate genetic Chemical & the language of
epigenetics. “People may be predisposed to developing many diseases
including cancer, but environmental factors often are the ones to
decide if it goes off or not, using these epigenetic pathways,”
says geneticist Bryan Turner, University of Birmingham in
4. How the brain thinks and creates memories?
The brain is a chemical computer. Mutual reactions between nerve
cells that build its circuits mediated by molecules called
neurotransmitters (neuro & transmitters). These messengers cross
the synapse, the contact point where the nerve cells coupling
together. The most impressive parade of the chemistry of thinking
is perhaps the operation of memory, a process in which abstract
ideas and principles, such as a phone number or emotional
associations, embedded in certain situations of neural network
using continuous chemical signals. How chemistry creates a
continuous and dynamic memory and also allows to recall, to change
and to forget it?
We know part of the answer. Cascade of biochemical processes, is
leading a change in the amount of neurotransmitter molecules at the
synapse that in turn triggers learning of reflexes of the leg.
However, even this simple aspect of learning has both short-term
steps and long term. In contrast, more complex memory processes
called declarative memory (like the memory of people, places, etc.)
occurs via a different mechanism elsewhere in the brain. These
processes involve the operation of a protein called the NMDA
receptor found on certain neurons. Blocking this receptor using
drugs prevents the saving of many types of declarative
<img ALT="" src="/blog7style/images/common/sg_trans.gif" real_src ="/readers//chemicalsynapseschema_1.jpg" WIDTH="257" HEIGHT="329"
TITLE="（转）化学世界的十大未解之谜&（10&Unsolved&Mysteries&in&Chemistry）" />
The declarative day-to-day memories are often encoded through a
process called long-term empowerment, involving NMDA receptors and
is accompanied by expansion of the neurons synapse region. The
synapse grows, it “strengthens” the relationship with neighboring
cells, i.e. the voltage soak up nerve signals from the synaptic
junction. Biochemistry of this process became apparent in recent
years. The process involves the formation of fibers within the
nerve cell built from the Actin protein, material participant in
building the basic skeleton of the cell and determines the size and
shape. But if the biochemical factors prevent the stabilization of
new fibers, the process stops and the fibers break down.
Once a long-term memory passes an encoding process, through
simple or complex learning processes, it is actively maintained by
activation of genes that cause certain proteins to react. Right now
it seems that this process may involve a molecule called Prion.
Prions are proteins that can oscillate between two different
spatial forms. One water-soluble forms and the other is not
soluble. Non-soluble form acts as a catalyst causing similar
molecules to become an also-solvent and coagulate. Prions were
discovered for their role in neurodegenerative diseases such as mad
cow disease, but it is now clear that the action of prions also
have a beneficial role: accumulation of Prions marks a synapse to
use in order to keep a memory.
In the story of memory operations there are still large gaps,
many of whom are waiting to be closed by clarifying the chemical
details. For example, how a memory is being removed after learned?
“This is a profound problem that we are just beginning to analyze”
says neurobiologist and Nobel winner Eric Kandel of Columbia
University.
Understanding the chemistry of memory offers us the
controversial temptation of memory improvement with medication. We
already know several memory stimulating substances, such as sex
hormones and synthetic chemicals, acting on nicotine receptors,
glutamine, serotonin and other neurotransmitters. In fact, the
complex sequence of steps leading to learning and long-term memory
has many possible targets for memory improvement drugs of this
kind, says neurobiologist Gary Lynch of the University of
California at Irvine.
5. How many chemical elements are there?
Periodic Table of Heavy Metals (Photo credit: )
The Periodic table on the walls of classrooms needs regularly
updating because the number of elements continues to rise.
Scientists use particle accelerators to create collisions between
atomic nuclei and create new “super & heavy” foundations in which
the nucleus has more protons and neutrons than which the nucleus of
about 92 elements found in nature. These radioactive nucleuses are
unstable and they decay and fall apart sometimes in an instant. But
as long as these are synthetic elements, like Ciborium (atomic
number 106) and Seam (108) exist there are foundations and have
distinct chemical properties. Through amazing experiments,
scientists want to explore some of these features through a small
number of Ciborium and Seam atoms in the brief moments before they
Studies examining more than just the physical limits of the
periodic table, they also examine the fundamental limits: Do the
“super & heavy” foundations continue to present the trends and
behavior that characterize the chemical periodic table in the first
place? The answer is that some of them continue to do so, and some
do not. In particular, these nuclei, with a larger mass, attract
the electrons nearest the nucleus of such intensity that the
electrons are moving at speeds close to light speed. Under these
conditions the electron mass increases, according to special
relativity, and it can completely disrupt the system of quantum
energy levels which depend on their chemical behavior & and the
very periodic of the table.
Nuclei with “magic numbers” of some protons and neutrons are
more stable. So some researchers hope to find the area in the
periodic table known as the “instability” area. This area is just
past the artificial elements we can found using the technology in
our hands, and in it the heavy nuclei will be able to exist for a
longer period of time. And yet, is there a fundamental limit to
their size? A simple calculation suggests that the Relativity
theory prevents the existence of nuclei with more than 137 protons.
However, more complex calculations challenge the limit. “The
Periodic system will not end in 137, in fact, it would never end,”
insists the nuclear physicist Walter Greiner from University Johann
Wolfgang Goethe in Frankfurt, Germany. Experimental test of this
argument is too far off.
6. Is it possible to build computers from carbon?
Computer chips made of graphene, a network of carbon atoms, will
probably be faster and more powerful than computers based on
silicon. Graphene explorers won the Nobel Prize in physics in 2010.
However, the success of nanotechnology based on graphene, or other
types of carbon, will ultimately depend on the ability of chemists
to create atomically accurate structures.
In 1985 Bucky balls were discovered the hollow molecules,
cage-like, made only of carbon atoms. This was the starting point
for something much bigger. Six years later the carbon nanotubes
appeared. Their constituent atoms arranged in hexagonal network, a
network similar to chicken coops, just as they are arranged in
layers of carbon graphite. Because these nano & carbon tubes are
hollow, extremely strong, rigid and electrical conductivity, they
are very promising for a variety of applications, from carbon-based
composite materials with high strength, to tiny electrical wires
and electronic devices, and even tiny molecular capsules and
membranes to filter water.
However, despite the promise, nanotubes carbon nanomaterials
have not yielded many commercial applications. For example,
researchers could not solve the connection problem of complex
electronic circuits tubes. Recently, graphite became interesting
again after a way to separate its layers was found. Grahites layers
are similar to chicken wire, and are called graphene. This material
may form the basis for very small circuits, cheap and hard.
Hopefully, it can be used in the computer industry for narrow
ribbons of graphene networks, derived the appropriate sizes and
atomic precision, to build chips demonstrate better performance
than those based on silicon.
&”Graphene can be designed in a way you can get
over their attachment problems of nanotubes carbon nanomaterials
and their location,” says carbon expert Walt de-Heer from Georgia
Institute of Technology. However, he adds that the methods
(currently accepted in the computer industry), such as chemical
etching, are too crude methods to design a graphene circular with
an accuracy of a single atom.&De-Heer afraid that
the graphene technology get here corrent status due to rating
rather than rigorous science. Perhaps the key to engineering such
accurate atomic scale is the use of methods of organic chemistry:
building bottom-up graphene circuitry, meaning combining several
poly-aromatic molecules that containing some hexagonal carbon rings
that look like small pieces of graphene surface. Such methods could
open the gate for the future graphene-based electronics.
7. How can we use more solar energy?
<img ALT="" src="/blog7style/images/common/sg_trans.gif" real_src ="/readers//solarenergyinformation_1.jpg" WIDTH="292" HEIGHT="282"
TITLE="（转）化学世界的十大未解之谜&（10&Unsolved&Mysteries&in&Chemistry）" />
Every sunrise reminds us that we exploit only a pitiful fraction
of the cleanest huge energy resource & the sun. The main problem is
cost: cost of photovoltaic panels & ordinary voltaic, made of
silicon, still limits their use. However, life on Earth, almost all
of them are driven, ultimately, through photosynthesis by solar
light, solar cells are proving we do not have to be very effective,
provided that, like leaves, it will be possible to produce them in
large quantities and at low enough prices.
“One of the ultimate goals of research in solar energy is to use
sunlight to produce fuels,” says Dioons Gast Arizona State
University. The easiest way to produce fuel from solar energy is
the decomposition of water and the creation of gaseous hydrogen and
oxygen. Nathan S. Lewis and his colleagues of the California
Institute of Technology (Caltech) are developing an artificial leaf
that should do it through wires & made of nano silicon.
In the early 2011 Daniel Nocera and colleagues from the
Massachusetts Institute of Technology (MIT) revealed the
development of the silicon-based membrane containing a catalyst
that react through cobalt that decompose water. Nocera estimates
that 4 liters of water will be enough to provide enough fuel for
one day to one house in a developing countries. “Our goal is to
make each home its own power plant,” he says.
Water decomposing through a catalyst is still a difficult task.
“in Cobalt catalysts, such as that of Nocera, and other newly
discovered catalysts,that are& based on other
common metals, lies the promise,” says Gast, but still no one found
the ideal cheap catalyst. “We still do not know how the natural
photosynthesis catalyst, that is based on four manganese atoms and
one calcium atom, operates” adds Gast.
Gast and his colleagues are seeking to build artificial
photosynthesis and molecular mechanisms that will be similar to the
sources of the biological inspiration. His team was able to
synthesize a number of elements that can be incorporated into such
mechanisms. However, much work still needed on that front. Organic
molecules such as those in which nature uses tend to disintegrate
quickly. Plants continuously produce new proteins, replacing the
ones that broke, but artificial leaves, on the other
hand,& are not equipped (yet) with full chemical
synthesis mechanism as it works in a living cell.
8. What is the best way to produce biofuels?
Instead of producing fuels
, maybe we
should leave the task of storing solar energy to plants and
then turn the
plant material into fuel? Biofuels, like ethanol,
from corn, and bio & diesel, produced from seed, have been
integrated into the energy markets. However, they threaten to
replace food crops, especially in developing countries where
biofuels gain more than food to the population at home. And the
numbers are scary: In order to meet nowadays fuel demand it will
require the expropriation of huge areas of fertile land.
Therefore, converting food into energy is
perhaps not the best approach. One answer is to take advantage of
other less vitality forms of bio & mass. The volume of debris that
agriculture and forests produce in the U.S. each year is enough to
provide a third of gasoline and diesel consumption of the annual
transportation.
In order to make biofuels of this less quality
mass one should break very rigid molecules such as lignin and
cellulose, the building blocks of plants. Chemists already know how
to do so, but current methods tend to be too costly, inefficient
and hard to do inhigh enough volume to meet the enormous amounts of
fuel consumption economy.
One challenge is breaking the
lignin carbon & oxygen bridge between aromatic carbon rings,
figures benzene. John Hartwig and Alexei Sergeyev from
University
of Illinois recently managed to overcome this challenge by using
nickel-based catalyst. Hartwig says that if you want to use
bio-mass as a substitute for chemical raw materials and fuel
materials created from fossil fuels, chemists must produced aromatic
substances (molecules of aromatic skeleton consisting of coins)
from bio-mass. Lignin is the only major potential source of
aromatic substances in the bio-mass.
9. Can we find new ways to produce drugs?
The heart of chemistry is both practical and creative: to build
molecules. This is the key to everything from new materials to the
rise of antibiotics that can overcome&resistant
One of the hopes of the 90s was combinations chemical:
construction of thousands of new molecules, using random
combinations of building blocks, and scanning the products in order
to identify the the ones that operate best to complete the task.
However, nowadays this area which was declared as the future of
medical chemistry is no longer of interest, because it almost did
not bring any practical use.
<img ALT="" src="/blog7style/images/common/sg_trans.gif" real_src ="/readers//no_1.jpg" WIDTH="408" HEIGHT="182"
TITLE="（转）化学世界的十大未解之谜&（10&Unsolved&Mysteries&in&Chemistry）" /> Successful second round for
combinational Chemistry?
However, combinations chemical have a second more successful
round. It can work only if we can produce a sufficiently broad
range of products, to find better ways to choose the successful
molecules and exhaust their tiny quantities. Biotechnology can be
of help. For example, each molecule can be bonded to a bar-code
based on DNA that can help in identifying the molecules and help
producing them. Another approach, is that researchers can improve
the library candidate molecules through a process similar to a
Darwinian evolution in vitro. They can, for example, encode
molecules of protein-based drugs with a suitable DNA sequence and
use a reproduction mechanism which tends to errors. Such
duplication manufacturing new versions of the most successful
molecules, and found improvements in each round of replication and
selection.
Other new methods are based on nature’s skill of connecting
molecular portions to each other in fixed arrangements. Proteins,
for example, has an exact arrangement of amino acids since this
sequence is encoded in genes. Using this model, the future chemist
can program molecules to assemble themselves independently. This
approach also has a “green” advantage since it reduces the amount
of byproducts that are characteristic of traditional chemical
production processes and waste of energy and raw materials that
accompanies them.
David Liu and his colleagues of Harvard University are working
in this approach. They programmed the desired molecular structure
via connecting a short DNA strands of its building blocks. They
also created a molecule that can move on DNA, read the code and
connect small molecules, according to a specific order to the
building blocks in order to create the desired molecule. A process
analogous to synthesis of proteins in living cells. Liu’s method
may be useful in building new drugs. “Many scientists engaged in
life sciences at the molecular level believe that giant molecules
will have a more central, and perhaps even decisive, role in future
healing processes,” says Liu.
10. Can we continuously monitor our chemistry?
More and more chemists strive to not only create molecules but
also to interact with them: use chemistry as an information
technology that will be used to interface with everything from live
cells to regular computers to fiber optic communications.
This vision is in part old ideas: chemical sensors in which
chemical reactions are used to report blood glucose concentrations
were in the 60s of the 20th century, although recently they have
become cheap, portable and popular enough to serve as a monitoring
tool for diabetes. However, chemical sensing may have countless of
uses: identifying contaminants in food and water at very low
concentrations, for example, or monitoring of pollutants or rare
gases in the atmosphere. Fast, inexpensive, sensitive and are more
common Chemical sensors will bring considerable progress in these
However, the area where the new chemical sensors will have the
most dramatic effect is probably the area of &#8203;&#8203;bio-medicine. Some
of the outcomes of cancer genes, for example, appear in the blood
circulation long before the disease turns detectable in ordinary
laboratory test. Detection of these substances may lead to early
and more accurate diagnosis than we have right now. Quick
determination of genetic profiling will allow customized drug
regimen, which will reduce the risk of side effects and will allow
the use of several drugs, which are not used today because these
drugs are dangerous to some minority with particular gene.
Chemists contract an unobtrusive continuous monitoring of a
variety of biochemical markers of health and illness. Maybe
surgeons can use real-time information and automated systems will
provide medicines. This future vision depends on the development of
chemical methods for selective sensing of certain substances and
signaling their presence even at very low concentrations.
化学世界的十大未解之谜
------Philip Ball
绝大部分最精深的科学问题，以及一些对人类而言最为紧迫的问题，都与原子或者分子有关。
1、生命从何而来？
存在太多的科学假说，但是科学家们的挑战是找到验证假说的方法。生命的本质是一个可以充当模板进行自我复制，并能与“复制品”分开的分子系统。
2、分子如何形成？
科学家们探索分子的形成过程中创造了量子力学理论、杂化轨道理论，理论化学的发展仍然尚未完善；科学家们并没有完全一致的认为这些理论模型足够精确。
3、环境如何影响人类基因？
“人类的很多疾病都与遗传相关，包括癌症在内，但是一种潜在的疾病最终是否发作，通常还要看环境因素能否通过表现遗传的方式起作用。”
生活在不同环境下的人会因为致癌物质含量的不同导致癌症的概率明显不一样。
4、大脑如何思考，并形成记忆？
神经元之间的相互作用构成的“环路”是通过分子介导的。化学物质是如何创造出一段既持续又动态，还能够被回忆、修改以及遗忘的记忆呢？
5、到底存在多少种元素？
依据相对论的一项简单的计算，电子无法被用有超过137个质子的原子核束缚。有科学家认为，元素周期表，绝对不会在第137号元素前止步不前。但是要验证这个断言，目前看来还是一个遥远的目标。
6、我们能用碳元素制造出电脑吗？
各种碳纳米材料推向实际应用，最终还依赖与化学家能否创造出精密度达原子级别的结构。
7、如何捕获更多的太阳能？
传统光伏电池板的高昂成本限制了它获取太阳能的使用，科学家们仍在努力发展廉价利用太阳能产生燃料的反法——太阳能分解水。
8、制造生物燃料的最佳途径是什么？
打破木质素，需要打断它的分子结构中氧原子与苯环上碳原子的连接。尽管存在好的基于镍元素的催化剂可以从中获得芳香族化合物，但是催化转化需要原材料极度纯净，这是横亘在化学家面前的一大难题。因为木材在催化转化看来，是一种非常“肮脏”的材料。必需找到合适的催化剂！
9、我们能研制出全新类型的药物吗？
组合化学的时代已经渐渐失去当初的光环。
合成足够多的分子类型，然后找到理想的方法，从中筛选出需要的几种；借用自然规则，按指定方式来连接分子片段，通过编程的方式，让化学分子自组装。
10、我们能实时监测自身的化学变化吗？
在活细胞与计算机之间搭起一座桥梁，并通过光纤来传递这些信息。化学会改变人类的未来。
已投稿到：
以上网友发言只代表其个人观点，不代表新浪网的观点或立场。}