Resiko Penggunaan Ponsel Terus-menerus

Tidak bisa dipungkiri bahwa telepon seluler (ponsel) telah banyak menghadirkan berbagai kemudahan dalam hidup manusia. Meski banyak diperdebatkan, banyak kalangan khawatir akan dampak negatif dari radiasi yang ditimbulkan.

Penelitian terbesar yang pernah dilakukan tentang bahaya ponsel telah membantah adanya risiko kanker otak pada penggguna ponsel. Penelitian yang dilakukan sendiri oleh organisasi kesehatan dunia (WHO) tersebut menunjukkan risikonya tidak terlalu besar untuk dikhawatirkan.

Namun penelitian terbaru di India kembali menegaskan adanya ancaman kanker terutama pada anak dan remaja. Sang peneliti, Prof Girish Kumar bahkan mengatakan bahaya radiasi juga terdapat di sekitar menara Base Transceiver Station (BTS).

"Satu BTS bisa memancarkan daya 50-100W. Negara yang punya banyak operator seluler seperti India bisa terpapar daya hingga 200-400W. Radiasinya tak bisa dianggap remeh, bisa sangat mematikan," ungkap Prof Kumar.

Dikutip dari DNAindia, berikut ini sejumlah dampak negatif yang bisa ditimbulkan akibat radiasi yang berlebihan dari ponsel dan menara BTS:

1. Risiko kanker otak pada anak-anak dan remaja meningkat 400 persen akibat penggunaan ponsel. Makin muda usia pengguna, makin besar dampak yang ditimbulkan oleh radiasi ponsel.

2. Bukan hanya pada anak dan remaja, pada orang dewasa radiasi ponsel juga berbahaya. Penggunaan ponsel 30 menit/hari selama 10 tahun dapat meningkatkan risiko kanker otak dan acoustic neuroma (sejenis tumor otak yang bisa menyebabkan tuli).

3. Radiasi ponsel juga berbahaya bagi kesuburan pria. Menurut penelitian, penggunaan ponsel yang berlebihan bisa menurunkan jumlah sperma hingga 30 persen.

4. Frekuensi radio pada ponsel bisa menyebabkan perubahan pada DNA manusia dan membentuk radikal bebas di dalam tubuh. Radikal bebas merupakan karsinogen atau senyawa yang dapat memicu kanker.

5. Frekuensi radio pada ponsel juga mempengaruhi kinerja alat-alat penunjang kehidupan (live saving gadget) seperti alat pacu jantung. Akibatnya bisa meningkatkan risiko kematian mendadak.

6. Sebuah penelitian membuktikan produksi homon stres kortisol meningkat pada penggunaan ponsel dalam durasi yang panjang. Peningkatan kadar stres merupakan salah satu bentuk respons penolakan tubuh terhadap hal-hal yang membahayakan kesehatan.

7. Medan elektromagnet di sekitar menara BTS dapat menurunkan sistem kekebalan tubuh. Akibatnya tubuh lebih sering mengalami reaksi alergi seperti ruam dan gatal-gatal.

8. Penggunaan ponsel lebih dari 30 menit/hari selama 4 tahun bisa memicu hilang pendengaran (tuli). Radiasi ponsel yang terus menerus bisa memicu tinnitus (telinga berdenging) dan kerusakan sel rambut yang merupakan sensor audio pada organ pendengaran.

9. Akibat pemakaian ponsel yang berlebihan, frekuensi radio yang digunakan (900 MHz, 1800 MHz and 2450 MHz) dapat meningkatkan temperatur di lapisan mata sehingga memicu kerusakan kornea.

10. Emisi dan radiasi ponsel bisa menurunkan kekebalan tubuh karena mengurangi produksi melatonin. Dalam jangka panjang, kondisi ini dapat mempengaruhi kesehatan tulang dan persendian serta memicu rematik.

11. Risiko kanker di kelenjar air ludah meningkat akibat penggunaan ponsel secara berlebihan.

12. Medan magnetik di sekitar ponsel yang menyala bisa memicu kerusakan sistem syaraf yang berdampak pada gangguan tidur. Dalam jangka panjang kerusakan itu dapat mempercepat kepikunan.

13. Medan elektromagnetik di sekitar BTS juga berdampak pada lingkungan hidup. Burung dan lebah menjadi sering mengalami disorientasi atau kehilangan arah sehingga mudah stres karena tidak bisa menemukan arah pulang menuju ke sarang.

Plant Tissue

 A.    Young tissues / meristem

• Apical Meristem

Apical meristem is at the root tip and the shoot buds, producing cells for the plant to grow lengthwise. Elongation is also called primary growth, allowing the roots to make fabric in the soil and shoots to improve presentation of sunlight and carbon dioxide.

o Growth of Primary Roots

Term growth will be concentrated near the root tip, which is located 3 zone cells with successive stages of primary growth. From the root tip towards the top, there is a zone of cell division, elongation zone and maturation zone.

o Growth of Primary Branch

Apical meristem of a shoot is a dome-shaped mass of cells that divide at the end of the terminal bud.

• Lateral Meristem

Two lateral meristem function in secondary growth of vascular cambium, which produces secondary xylem (wood) and phloem, and cambium cork.

o Secondary Stem Growth

Vascular cambium is a cylinder composed of meristematic cells that form secondary vascular tissues. During secondary growth, the epidermis produced by primary growth will peel, dry, and fall from the stem. The skin will be replaced by new protective tissues produced by the cork cambium,
o Secondary Growth of Roots

Both the lateral meristem, ie the vascular cambium and cork cambium also develops and produces secondary growth in roots. Vascular cambium is formed in the Stele and produce secondary xylem towards the inside and secondary phloem towards the outside. After the Stele diameter grows larger, the cortex and epidermis broken and loose.

• Interkalar Meristem

Meristem is located between the primary meristem tissue and adult tissue. Interkalar meristem cell growth causes the stem length more quickly, before the growth rate

B.     Jaringan dewasa

1.   Basic tissue (parenchymal)

Parenchymal tissue
Parenchymal tissue is called the basic network because many found almost in every part of plants, such as pith, cortex of roots and stems, leaf mesophyll, endosperm of seeds, fruits fleshy, core radius, and also contained as constituent elements of xylem and phloem, both primary and secondary.
• The characteristics of parenchymal tissue
~ Generally, large cells and thin-walled.
~ Cell was alive and contain chloroplasts.
~ Contains a lot of cavities between cells.
~ Contains many vacuoles.
~ Location of meeting tidal cell (rarely).
• Forms of parenchymal tissue
~ Jarinngan palisade parenchyma, has a round shape elongated / oval such as poles or fence rows and in the palisade parenchyma cells have chlorophyll.
~ Network parenchymal sponges, have a space between the cavity is very large and irregular, the sponges contained small amounts of chlorophyll (unlike a palisade).
~ Network star parenchyma (aktinemkim), has a shape like a star because pentagonal dangling.
~ Network parenchymal folds, found in pine and rice, which forms denngan berllipat inward as well as many contain chloroplasts.
• The function of parenchymal tissue
~ Parenchymal assimilation
There on the green parts of the plant. In his cell there in chloroplasts which plays an important role in the process of photosynthesis. On the assimilation parenchyma tissue forms that dominate there are two kinds, namely forms such as pillars, called tissue pillars and form spongy tissue called sponges. On the pine needle-like leaves are reduced, the assimilation parenchyma walls are folded inward folds called the parenchyma.
~ Parenchymal air
Large inter-cell space, round the constituent cells as a means of flotation in the water. For example parenchyma on water hyacinth petiole, the cells formed branched fingers or a star. Tues functioning parenchymal air store called aerenkim.
~ Parenchymal hoarders
Parenchymal cells contain food reserves contained in the pith of the stem, root tuber, bulb, rhizome root (rhizome), or seeds, etc..
~ Parenchymal water
Cells filled with water, to defend itself against drought
~ Parenchymal carrier
There on the carrier network. In this network parenchymal wall can undergo secondary thickening.

2.   Brace tissue

To strengthen his body, plants require Brace tissue, there are two kinds of brace tissue, namely:

·   Kolenkim

Characteristic of kolenkim:

a.       The cells are alive.

b.      Thin-walled, because the cells retain kolenkim active protoplasts that can eliminate the thickening of the wall when the cell is stimulated to divide.

c.       The walls contain cellulose, pectin, and hemicellulose .

d.      Soft, pliable not have lignin. But in old plants, the cell wall harden and has lignin also turn into sklerenkim.

e.       Thickening wall is not evenly.

f.       There is at the active plant, usually there directly below the epidermis.

g.      Is plastic (clay)

Based on the ways thickening kolenkim cells, known to some type kolenkim:

a.       Angle Kolenkim (angular)

Thickening  extends to the corner of the cell.

b.      Plate / board Kolenkim ( lamellar)

Thickening occurs in the tangential wall, which is part of the wall parallel to the surface of the organ.

c.       Kolenkim tubular  ( lakunar)

Thickening occurs in the cell that limit the space between cells or between two adjacent cells.

·   Sklerenkim

Characteristics of sklerenkim :

a.       The cells are a dead.

b.      Strong and rigid walls because it contains lignin.

c.       There is at the adult plant.

d.      Wall thickness, because the more defensive sklerenkim cell wall and can not be immediately eliminated, although the protoplasts are still there. However, most cells lose the protoplast  sklerenkim as an adult.

e.       Elastic

f.       Thickening wall is evenly.

Kinds of sklerenkim :

a.       Sklereid

Sklereid often called stone cells, because the walls are hard. Size and shape vary. There is a group, or stand alone.In the body of plants, sklereid contained in the carrier file, parenchymal cells, cortical stem, petiole, leaf meat, roots, fruits and seeds.

b.      Serat (serabut)

Most fiber is a long element with the tip of the pointed, narrow lumen and thick secondary wall. Fibers found in the xylem cells or phloem, or is a layer and is associated with the carrier file.

Fiber can be divided into two, namely hard fibers and soft fiber. Hard fiber have the woody walls because of ligneous plants are generally produced by monocots. While soft fiber is not always contain lignin, is flexible and supple, produced by the dicotyledonous plants.

3.   Protective Tissues

Epidermis tissue
The epidermis is the cell layers that are most out of the primary plant equipment, such as: roots, stems, for modern, flowers, fruits, and seeds. In this case beberpa botanist has been suggested as follows:
• ALLEN, epidermis in the "root" is called as rhizoderma or epiblem;
• SCHMIDT, epidermis in the "trunk" is derived from the outermost cell layer of the apical meristem; at tunica area.
• HANSTEIN, epidermal layers on the trunk that originated from a single cell layer called dermatogen;
• HABERLANDT, the epidermis is derived from primordial epidermis (epidermis or will be known by protoderm), the origin of initial cells separate.

Epidermal cells derived from primary meristem cells. Location of epidermal cells tightly so that no spaces between cells (non-inter-cellular spaces). There are a few protoplasts were attached to the walls of his cell, indicating epidermal cells are still alive. Vakuola which of these are in the middle, fluid-filled cells can also be colored or colorless. Plastids are usually absent in epidermal cells, epidermal cells have leukoplas, tiny. Chloroplasts are usually present in epidermal cells and used as servants in carrying out the process of photosynthesis.
Thickening, thickening of the epidermal cell wall (thickening of the secondary-thickening), consist of cellulose tangible as the lines of (lamella). On the opposite cell wall thickening was not only accompanied by substance kutin cuticle is also located on the cell membrane. Cuticle any artifacts on the cover cells of the stomata. Stomata are holes located in the epidermis of each limited by two "guard cells" (cells cover). Trichomata (hairs) is derived from the epidermis which form, structure, and function varies. Order trichomata distinguish between unicellular and multicelluler. Epidermal layers are divided into uniseriate epidermis and hypodermic.

 Cork Tissue
• Eksodermis
Formed because of the change function of the cell layers below the epidermis is lost or damaged roots. On the inner wall of his cell that contains suberin lamella-lamella.
• Endodermis
Cell layer contained in the root cell walls often bergabus. This layer is sometimes called the cortex (bark) if the inner and outer cylinders if the center
• Skin cork (periderm)
A network becomes a substitute when episermis epidermis is damaged, peeling, suffered death. Periderm divided into 3, namely: Phellogen, phellem, phelloderm.

Titration

Titration is a general class of experiment where a known property of one solution is used to infer an unknown property of another solution. In acid-base chemistry, we often use titration to determine the pH of a certain solution.

A setup for the titration of an acid with a base is shown in : 

Figure %: A titration setup

We use this instrumentation to calculate the amount of unknown acid in the receiving flask by measuring the amount of base, or titrant, it takes to neutralize the acid. There are two major ways to know when the solution has been neutralized. The first uses a pH meter in the receiving flask adding base slowly until the pH reads exactly 7. The second method uses an indicator. An indicator is an acid or base whose conjugate acid or conjugate base has a color different from that of the original compound.

Titration Curves

A titration curve is drawn by plotting data attained during a titration, titrant volume on the x-axis and pH on the y-axis. The titration curve serves to profile the unknown solution. In the shape of the curve lies much chemistry and an interesting summary of what we have learned so far about acids and bases.

The titration of a strong acid with a strong base produces the following titration curve:

Figure %: Titration curve of a strong base titrating a strong acid

Note the sharp transition region near the equivalence point on the . Also remember that the equivalence point for a strong acid-strong base titration curve is exactly 7 because the salt produced does not undergo any hydrolisis reaction

However, if a strong base is used to titrate a weak acid, the pH at the equivalence point will not be 7. There is a lag in reaching the equivalence point, as some of the weak acid is converted to its conjugate base. You should recognize the pair of a weak acid and its conjugate base as a buffer. In , we see the resultant lag that precedes the equivalence point, called the buffering region. In the buffering region, it takes a large amount of NaOH to produce a small change in the pH of the receiving solution.

Figure %: Titration curve of a strong base titrating a weak acid

Because the conjugate base is basic, the pH will be greater than 7 at the equivalence point. You will need to calculate the pH using the Henderson-Hasselbalch equation, and inputting the pK _b and concentration of the conjugate base of the weak acid.

The titration of a base with an acid produces a flipped-over version of the titration curve of an acid with a base. pH is decreased upon addition of the acid.

Note that the pH of a solution at the equivalence point has nothing to do with the volume of titrant necessary to reach the equivalence point; it is a property inherent to the composition of the solution. The pH at the equivalence point is calculated in the same manner used to calculate the pH of weak base solutions in calculation Ph

When polyprotic acids are titrated with strong bases, there are multiple equivalence points. The titration curve of a polyprotic acid shows an equivalence point for the each protonation:

Figure %: Titration curve of a strong base titrating a polyprotic acid

The titration curve shown above is for a diprotic acid such as H₂SO₄ and is not unlike two stacked . For a diprotic acid, there are two buffering regions and two equivalence points. This proves the earlier assertion that polyprotic acids lose their protons in a stepwise manner.