a further illustration of the invention may be described with reference to the following examples . to isolate gq - 5 , the dried resins of toxicodendron vernicifluum ( 17 kg ) ( yunnan corporation of materiamedica , kunming , p . r . china ) were extracted with 80 % ethanol ( 3 × 20 l ) at room temperature . the extracts were concentrated under reduced pressure , and suspended in water followed by partition with ethyl acetate ( 3 × 5 l ). the extract ( 220 g ) from ethyl acetate was submitted to a silica gel column ( 200 - 300 mesh , 12 × 150 cm , 2 . 5 kg , qingdao marine chemical inc ., qingdao , p . r . china ), eluted with a gradient of chcl 3 meoh ( 100 : 0 - 80 : 20 ) to yield 10 fractions . the fraction 4 ( 15 g ) was subjected to a mci gel chp 20p column ( 75 - 150 μm , mitsubishi chemical industries , tokyo , japan ), eluted with gradient aqueous acetone ( 80 : 20 - 100 : 0 ) to yield fractions 4 . 1 and 4 . 2 . among them , the fraction 4 . 2 ( 11 . 3 g ) was filtrated on sephadex lh - 20 ( chcl 3 meoh , 6 : 4 , amersham pharmacia , uppsala , sweden ) to yield gq - 5 ( 10 g ). the spectroscopic and chemical methods were used to identify the structure of gq - 5 . the 1 h nmr spectrum using bruker drx - 500 nmr spectrometer ( bruker daltonics , germany ) indicated the diagnostic signals of one 1 , 2 , 4 - trisubstituted benzene group , one methyl , and one aliphatic chain . the 13 c nmr and dept spectra revealed one methyl , five methine , and three quaternary carbons ( two of them are oxygenated ). mass spectra ( esi - ms ) ( api qstar pulsar 1 spectrometer , ab sciex , usa ) and high resolution elms ( autospecprimier p776 instrument , waters , usa ) analyses indicated that the molecular formula of gq - 5 was c 21 h 34 o 2 . the nmr data of gq - 5 were in agreement with those of 3 -[( z )- pentadec - 8 - enyl ] catechol . in addition , the position and geometry of the double bond in the side chain was confirmed by total chemical synthesis . the purity of gq - 5 was determined by analytic hplc using rp - 18 column under 280 , 254 , 230 , 225 and 210 nm , and then eluted by gradient aqueous meoh ( 85 % 400 %, 0 - 20 min ) only one symmetric peak was found in all the chromatograms in different detection conditions , indicating that gq - 5 is a hplc grade pure compound ( fig1 ). consistently , there was no impurity present in the 1 h nmr spectrum . to test the toxicity of gq - 5 , 20 c57bl6j little male mice which are 7 - 8 months old , healthy and clean , their weights are between 20 and 22 gram . antisepsis the feed and water , before and in the layoff period of the test , all the mice should be feed under the normal feeding condition . dissolve gq - 5 in 0 . 5 % propylene glycol , this liquor is given to little mice by intraperitoneal injection . the dosage of gq - 5 was 10 , 40 , 200 , and 800 mg / kg body weight of mice . after administration , they are observed for 7 days . mice intra - peritoneal injected with single dose of gq - 5 up to 800 mg / kg did not die or developed any adverse event during 7 - day observation . to test the toxicity of gq - 5 , rat proximal tubular cells ( nrk52e ) were seeded into 96 - well plates in a volume of 200 μl per well ( 1 × 10 5 cell / ml ) and incubated for 24 hours to allow cells to attach . the cells were then incubated with indicated amount of gq - 5 for 1 h . cell viability was determined by addition of 20 μl of 3 -( 4 , 5 - dimethylthiazol - 2 - yl )- 2 5 - diphenyltetrazolium bromide ( mtt ) at a concentration of 5 mg / ml . after incubation for 4 hours , the medium was removed and 150 μl of dmso was added to dissolve the formazan crystals . the absorbance was read at 540 nm by using imarktmmicroplate reader ( bio - rad ). as shown in fig2 , gq - 5 , over a complete pharmacologically relevant dose ( 0 . 25 - 4 μm ), did not affect the viability and proliferation of the cells . nrk52e and nrk49f cells were cultured in dmem - ham &# 39 ; s medium supplemented with 10 % fetal bovine serum . the cells reached at approximately 50 % confluence were used for in vitro experiments . cells were serum - starved for 12 h , and randomized into 6 groups : ( 1 ) controls ; ( 2 ) gq - 5 only ; ( 3 ) tgf - β1 only ; ( 4 ) tgf - β1 + gq - 5 0 . 1 μm ; ( 5 ) tgf - β1 + gq - 5 0 . 5 μm ; ( 6 ) tgf - β1 + gq - 5 2 . 5 μm . ( 2 ) gq - 5 only : pre - treated with gq - 5 ( 2 . 5 μm ) for 1 h , followed with dmem for 1 h ( 3 ) tgf - β1 only : pre - treated with dmso ( 0 . 1 %) for 1 h , followed with tgf - β1 ( 10 ng / ml ) for 1 h ( 4 ) tgf - β1 + gq - 5 0 . 1 μm : pre - treated with gq - 5 ( 0 . 1 μm ) for 1 h , followed with tgf - β1 ( 10 ng / ml ) for 1 h ( 5 ) tgf - β1 + gq - 5 0 . 5 μm : pre - treated with gq - 5 ( 0 . 5 μm ) for 1 h , followed with tgf - β1 ( 10 ng / ml ) for 1 h ( 6 ) tgf - β1 + gq - 5 2 . 5 μm : pre - treated with gq - 5 ( 2 . 5 μm ) for 1 h , followed with tgf - β1 ( 10 ng / ml ) for 1 h . gq - 5 was dissolved in dmso . cells were treated as described . cell lysates were immunoblotted with antibodies against phospho - smad3 , smad3 , phospho - smad2 , smad2 . as shown in fig5 a - 5b , incubation with tgf - β1 significantly induced phosphorylation of smad2 and smad3 in both nrk52e ( fig3 a ) and nrk49f cells ( fig3 b ). gq - 5 treatment attenuated tgf - β1 - induced smad3 phosphorylation in a dose - dependent manner , but did not affect tgf - β1 - induced smad2 phosphorylation . the inhibitory effect of gq - 5 was almost undetectable in nrk52e and nrk49f cells in the absence of tgf - β1 stimulation . nrk52e cells were cultured in dmem - ham &# 39 ; s medium supplemented with 10 % fetal bovine serum . the cells reached at approximately 50 % confluence were used for in vitro experiments . cells were serum - starved for 12 h , and randomized into 8 groups : ( 1 ) controls ; ( 2 ) gq - 5 only ; ( 3 ) tgf - β1 0 . 5 h ; ( 4 ) tgf - β1 0 . 5 h + gq - 5 ; ( 5 ) tgf - β1 1 . 0 h ; ( 6 ) tgf - β1 1 . 0 h + gq - 5 ; ( 7 ) tgf - β1 3 . 0 h ; ( 8 ) tgf - β1 3 . 0 h + gq - 5 ; ( 2 ) gq - 5 only : pre - treated with gq - 5 ( 2 . 5 μm ) for 1 h , followed with dmem for 1 h ( 3 ) tgf - β1 0 . 5 h : pre - treated with dmso ( 0 . 1 %) for 1 h , followed with tgf - β1 ( 10 ng / ml ) for 0 . 5 h ( 4 ) tgf - β1 0 . 5 h + gq - 5 : pre - treated with gq - 5 ( 2 . 5 μm ) for 1 h , followed with tgf - β1 ( 10 ng / ml ) for 0 . 5 h ( 5 ) tgf - β1 1 . 0 h : pre - treated with dmso ( 0 . 1 %) for 1 h , followed with tgf - β1 ( 10 ng / ml ) for 1 . 0 h ( 6 ) tgf - β1 1 . 0 h + gq - 5 : pre - treated with gq - 5 ( 2 . 5 μm ) for 1 h , followed with tgf - β1 ( 10 ng / ml ) for 1 . 0 h ( 7 ) tgf - β1 3 . 0 h : pre - treated with dmso ( 0 . 1 %) for 1 h , followed with tgf - β1 ( 10 ng / ml ) for 3 . 0 h ( 8 ) tgf - β1 3 . 0 h + gq - 5 : pre - treated with gq - 5 ( 2 . 5 μm ) for 1 h , followed with tgf - β1 ( 10 ng / ml ) for 3 . 0 h gq - 5 was dissolved in dmso . cells were treated as described . cell lysates were immunoblotted with antibodies against phospho - smad3 , smad3 , phospho - smad2 , and smad2 . as shown in fig4 , incubation with tgf - β1 significantly induced phosphorylation of smad2 and smad3 in nrk52e cells . gq - 5 treatment attenuated tgf - β1 - induced smad3 phosphorylation in a time - dependent manner , but did not affect tgf - β1 - induced smad2 phosphorylation . gq - 5 does not inhibit tgf - β1 - induced smad4 or smad7 expression , nor p38 , pi3k , erk phosphorylation in vitro nrk52e and nrk49f cells were cultured in dmem - ham &# 39 ; s medium ( gibco , life techologies , ny , usa ) supplemented with 10 % fetal bovine serum ( gibco , life techologies , ny , usa ). the cells reached at approximately 50 % confluence were used for in vitro experiments . cells were serum - starved for 12 h , and randomized into 4 groups : ( 1 ) controls ; ( 2 ) gq - 5 only ; ( 3 ) tgf - β1 only ; ( 4 ) tgf - β1 + gq - 5 ( 2 ) gq - 5 only : pre - treated with gq - 5 ( 2 . 5 μm ) for 1 h , followed with dmem for 1 h ( 3 ) tgf - β1 only : pre - treated with dmso ( 0 . 1 %) for 1 h , followed with tgf - β1 ( 10 ng / ml ) for 1 h ( 4 ) tgf - β1 + gq - 5 : pre - treated with gq - 5 ( 2 . 5 nm ) for 1 h , followed with tgf - β1 ( 10 ng / ml ) for 1 h gq - 5 was dissolved in dmso . cells were treated as described . cell lysates were immunoblotted with antibodies against smad4 , smad7 , phospho - p38 , p38 , phospho - pi3k , pi3k , phosphor - erk , and erk . as shown in fig5 a - 5b , gq - 5 did not affect the protein expression of smad4 or smad7 , nor the tgf - β1 - induced phosphorylation of p38 , erk and pi3k . gq - 5 selectively inhibits the phosphorylation of smad3 and smad2 in vivo male sprague - dawley rats with body weight 200 to 250 g were randomized into 4 groups ( n = 6 in each group ): ( 1 ) sham operated rats ; ( 2 ) uuo rats ; ( 3 ) uuo + gq - 5 d1 rats ; ( 4 ) uuo + gq - 5 d7 rats . ( 1 ) sham operated rats : daily intraperitoneal injection of 5 % propylene glycol ; ( 3 ) uuo + gq - 5 d1 rats : daily intraperitoneal injection of gq - 5 ( 40 mg / kg body weight ) right after uuo ; ( 4 ) uuo + gq - 5 d7 rats : daily intraperitoneal injection of gq - 5 ( 40 mg / kg body weight ) 7 days after uuo . uuo was performed using an established protocol as described . gq - 5 was dissolved in 5 % propylene glycol . rats were administrated with gq - 5 as described before . all the rats were sacrificed 14 days after uuo . immunohistochemical staining and western blot analyses were performed to examine the smad3 and smad2 phosphorylation in kidney tissue . as shown in fig6 , the phosphorylation of both smad3 and smad2 in renal tissue was significantly increased in uuo rats compared to sham controls . treatment of gq - 5 significantly inhibited smad3 but not smad2 phosphorylation . gq - 5 does not affect smad4 , smad7 expression or p38 , pi3k , erk phosphorylation in uuo kidneys male sprague - dawley rats with body weight 200 to 250 g were randomized into 3 groups ( n = 6 in each group ): ( 1 ) sham operated rats ; ( 2 ) uuo rats ; ( 3 ) uuo + gq - 5 rats . ( 1 ) sham operated rats : daily intraperitoneal injection of 5 % propylene glycol ; ( 3 ) uuo + gq - 5 rats : daily intraperitoneal injection of gq - 5 ( 40 mg / kg body weight ) right after uuo ; uuo was performed using an established protocol as described . gq - 5 was dissolved in 5 % propylene glycol . rats were administrated with gq - 5 as described before . all the rats were sacrificed 14 days after uuo . western blot analyses were performed to examine the smad4 , smad7 expression and p38 , pi3k , erk phosphorylation . as shown in fig7 a - 7b , gq - 5 did not affect the expression of smad4 and smad7 , or the phosphorylation of p38 , pi3k or erk in uuo rats . nrk52e cells were cultured in dmem - ham &# 39 ; s medium supplemented with 10 % fetal bovine serum . the cells reached at approximately 50 % confluence were used for in vitro experiments . cells were serum - starved for 12 h , and randomized into 3 groups : ( 1 ) controls ; ( 2 ) tgf - β1 only ; ( 3 ) tgf - β1 + gq - 5 . ( 2 ) tgf - β1 only : pre - treated with dmso for 1 h , followed with tgf - β1 ( 10 ng / ml ) for 2 h ( 3 ) tgf - β1 + gq - 5 : pre - treated with gq - 5 ( 2 . 5 μm ) for 1 h , followed with tgf - β1 ( 10 ng / ml ) for 2 h gq - 5 was dissolved in dmso . cells were treated as described immunofluorescence staining was performed to examine the nuclear translocation of smad2 , smad3 , and smad4 . as shown in fig8 , immunofluorescence staining reveled that pre - incubating nrk52e cells with gq - 5 significantly reduced the tgf - β1 - induced smad3 nuclear translocation . treatment with gq - 5 also reduced nuclear translocation of smad2 and smad4 . nrk52e cells were cultured in dmem - ham &# 39 ; s medium supplemented with 10 % fetal bovine serum . the cells reached at approximately 50 % confluence were used for in vitro experiments . cells were transiently transfected with a smad3 responsive promoter p ( gaga ) 12 - luc plasmid . pgl3 basic plasmid was co - transfected into the cells as control . cells were serum - starved for 12 h , and randomized into 6 groups : ( 1 ) controls ; ( 2 ) gq - 5 only ; ( 3 ) tgf - β1 only ; ( 4 ) tgf - β1 + gq - 5 0 . 1 μm ; ( 5 ) tgf - β1 + gq - 5 0 . 5 μm ; ( 6 ) tgf - β1 + gq - 5 2 . 5 μm ( 1 ) controls : transfected with pgl3 basic plasmid and incubated with dmem for 24 h ; ( 2 ) gq - 5 only : transfected with p ( gaga ) 12 - luc plasmid , pre - treated with gq - 5 ( 2 . 5 μm ) for 1 h , followed with dmem for 24 h ( 3 ) tgf - β1 only : transfected with p ( gaga ) 12 - luc plasmid , pre - treated with dmso for 1 h , followed with tgf - β1 ( 10 ng / ml ) for 24 h ( 4 ) tgf - β1 + gq - 5 0 . 1 μm : transfected with p ( gaga ) 12 - luc plasmid , pre - treated with gq - 5 ( 0 . 1 mm ) for 1 h , followed with tgf - β1 ( 10 ng / ml ) for 24 h ( 5 ) tgf - β1 + gq - 5 0 . 5 μm : transfected with p ( gaga ) 12 - luc plasmid , pre - treated with gq - 5 ( 0 . 5 mm ) for 1 h , followed with tgf - β1 ( 10 ng / ml ) for 24 h ( 6 ) tgf - β1 + gq - 5 2 . 5 μm : transfected with p ( gaga ) 12 - luc plasmid , pre - treated with gq - 5 ( 2 . 5 mm ) for 1 h , followed with tgf - β1 ( 10 ng / ml ) for 24 h gq - 5 was dissolved in dmso . cells were treated as described . promoter assays using a luciferase reporter system were performed to examine the smad3 - dependent collagen i promoter activity . as shown in fig9 , treatment with gq - 5 significantly inhibited tgf - β1 - induced smad3 - dependent collagen i promoter activity in a dose - dependent manner . gq - 5 reduced the tgf - β1 - induced α - sma , collagen i and fibronectin mrna expression nrk52e and nrk49f cells were cultured in dmem - ham &# 39 ; s medium supplemented with 10 % fetal bovine serum . the cells reached at approximately 50 % confluence were used for in vitro experiments . cells were serum - starved for 12 h , and randomized into 6 groups : ( 1 ) controls ; ( 2 ) gq - 5 only ; ( 3 ) tgf - β1 only ; ( 4 ) tgf - β1 + gq - 5 0 . 1 μm ; ( 5 ) tgf - β1 + gq - 5 0 . 5 μm ; ( 6 ) tgf - β1 + gq - 5 2 . 5 μm ( 2 ) gq - 5 only : pre - treated with gq - 5 ( 2 . 5 μm ) for 1 h , followed with dmem for 36 h ( 3 ) tgf - β1 only : pre - treated with dmso for 1 h , followed with tgf - β1 ( 10 ng / ml ) for 36 h ( 4 ) tgf - β1 + gq - 5 0 . 1 μm : pre - treated with gq - 5 ( 0 . 1 μm ) for 1 h , followed with tgf - β1 ( 10 ng / ml ) for 36 h ( 5 ) tgf - β1 + gq - 5 0 . 5 μm : pre - treated with gq - 5 ( 0 . 5 μm ) for 1 h , followed with tgf - β1 ( 10 ng / ml ) for 36 h ( 6 ) tgf - β1 + gq - 5 2 . 5 μm : pre - treated with gq - 5 ( 2 . 5 μm ) for 1 h , followed with tgf - β1 ( 10 ng / ml ) for 36 h gq - 5 was dissolved in dmso . cells were treated as described . cells were collected for mrna extraction . real - rime pcr was performed to examine the mrna expression of α - sma , collagen i and fibronectin . as shown in fig1 a - 10b , in compare with the control , treatment with gq - 5 significantly inhibited tgf - β1 - induced mrna expression of α - sma , collagen i and fibronectin in nrk 52e ( fig1 a ) and nrk 49f cells ( fig1 b ). gq - 5 reduced the tgf - β1 - induced α - sma , collagen i and fibronectin protein expression nrk52e and nrk49f cells were cultured in dmem - ham &# 39 ; s medium supplemented with 10 % fetal bovine serum . the cells reached at approximately 50 % confluence were used for in vitro experiments . cells were serum - starved for 12 h , and randomized into 6 groups : ( 1 ) controls ; ( 2 ) gq - 5 only ; ( 3 ) tgf - β1 only ; ( 4 ) tgf - β1 + gq - 5 0 . 1 μm ; ( 5 ) tgf - β1 + gq - 5 0 . 5 μm ; ( 6 ) tgf - β1 + gq - 5 2 . 5 μm ( 2 ) gq - 5 only : pre - treated with gq - 5 ( 2 . 5 μm ) for 1 h , followed with dmem for 48 h ( 3 ) tgf - β1 only : pre - treated with dmso for 1 h , followed with tgf - β1 ( 10 ng / ml ) for 48 h ( 4 ) tgf - β1 + gq - 5 0 . 1 μm : pre - treated with gq - 5 ( 0 . 1 μm ) for 1 h , followed with tgf - β1 ( 10 ng / ml ) for 48 h ( 5 ) tgf - β1 + gq - 5 0 . 5 μm : pre - treated with gq - 5 ( 0 . 5 μm ) for 1 h , followed with tgf - β1 ( 10 ng / ml ) for 48 h ( 6 ) tgf - β1 + gq - 5 2 . 5 μm : pre - treated with gq - 5 ( 2 . 5 μm ) for 1 h , followed with tgf - β1 ( 10 ng / ml ) for 48 h gq - 5 was dissolved in dmso . cells were treated as described . cells lysates were immunebloted with antibodies against α - sma , collagen i and fibronectin . as shown in fig1 a - 11b , treatment with gq - 5 significantly inhibited tgf - β1 - induced protein expression of α - sma , collagen i and fibronectinin nrk 52e ( fig1 a ) and nrk 49f cells ( fig1 b ). male sprague - dawley rats were randomized into 4 groups ( n = 6 in each group ): ( 1 ) sham operated rats ; ( 2 ) uuo rats ; ( 3 ) uuo + gq - 5 d1 rats ; ( 4 ) uuo + gq - 5 d7 rats . ( 1 ) sham operated rats : daily intraperitoneal injection of 5 % propylene glycol ; ( 3 ) uuo + gq - 5 d1 rats : daily intraperitoneal injection of gq - 5 ( 40 mg / kg body weight ) right after uuo ; ( 4 ) uuo + gq - 5 d7 rats : daily intraperitoneal injection of gq - 5 ( 40 mg / kg body weight ) 7 days after uuo . uuo was performed using an established protocol as described . gq - 5 was dissolved in 5 % propylene glycol . rats were administrated with gq - 5 as described before . all the rats were sacrificed 14 days after uuo . he staining , masson trichrome staining were performed to examine the renal tissue injury , and real - time pcr analyses , immunohistochemical staining , and western blot analyses were performed to examine α - sma , collagen i and fibronectin expression in kidney tissue as shown in fig1 a - 12d , uuo rats exhibited marked interstitial inflammation and fibrosis in renal tissue stained with hematoxylin - eosin and masson - trichrome . treatment with gq - 5 , either initiating right after or 7 days after operation , significantly reduced inflammatory cell infiltration and interstitial fibrosis score . intervention with gq - 5 also significantly inhibited the up - regulation of α - sma , collagen i and fibronectin in uuo rats at both mrna and protein level , suggesting that treatment of gq - 5 not only prevented renal fibrosis , but also ameliorated established renal fibrosis . gq - 5 selectively blocks the interaction of smad3 with tβri in vitro nrk52e cells were cultured in dmem - ham &# 39 ; s medium supplemented with 10 % fetal bovine serum . the cells reached at approximately 50 % confluence were used for in vitro experiments . cells were serum - starved for 12 h , and randomized into 4 groups : ( 1 ) controls ; ( 2 ) gq - 5 only ; ( 3 ) tgf - β1 only ; ( 4 ) tgf - β1 + gq - 5 ( 2 ) gq - 5 only : pre - treated with gq - 5 ( 2 . 5 nm ) for 1 h , followed with dmem for 1 h ( 3 ) tgf - β1 only : pre - treated with dmso for 1 h , followed with tgf - β1 ( 10 ng / ml ) for 1 h ( 4 ) tgf - β1 + gq - 5 : pre - treated with gq - 5 ( 2 . 5 nm ) for 1 h , followed with tgf - β1 ( 10 ng / ml ) for 1 h gq - 5 was dissolved in dmso . cells were treated as described . cell lysates were collected for immunoprecipitation to examine the interaction among tgfβ type i receptor ( tβri ), tβrii , smad3 and smad2 . as shown in fig1 a - 13c , tβri bound with tβrii , smad2 and smad3 upon tgf - β1 stimulation . treatment with gq - 5 significantly blocked the interaction of smad3 with tβri , but did not affect the interaction of smad2 with tβri . gq - 5 selectively blocks the interaction of smad3 with t3ri in vivo male sprague - dawley rats with body weight 200 to 250 g were randomized into 3 groups ( n = 6 in each group ): ( 1 ) sham operated rats ; ( 2 ) uuo rats ; ( 3 ) uuo + gq - 5 rats . ( 1 ) sham operated rats : daily intraperitoneal injection of 5 % propylene glycol ; ( 3 ) uuo + gq - 5 rats : daily intraperitoneal injection of gq - 5 ( 40 mg / kg body weight ) right after uuo ; uuo was performed using an established protocol as described . gq - 5 was dissolved in 5 % propylene glycol . rats were administrated with gq - 5 as described before . all the rats were sacrificed 14 days after uuo . immunoprecipitation analyses were performed to examine the interaction among tβri , tβrii , smad3 and smad2 . as shown in fig1 a - 14c , tβri bound with tβrii , smad2 and smad3 in uuo kidneys . treatment with gq - 5 significantly blocked the interaction of smad3 with tβri , but did not affect the interaction of smad2 with tβri . in the description above , numerous specific details are set forth . however , it is understood that embodiments of the invention may be practiced without these specific details . for example , well - known equivalent components and elements may be substituted in place of those described herein , and similarly , well - known equivalent techniques may be substituted in place of the particular techniques disclosed . in other instances , well - known structures and techniques have not been shown in detail to avoid obscuring the understanding of this description . the flowchart and block diagrams in the figures illustrate the architecture , functionality , and operation of possible implementations of systems and methods according to various embodiments of the present invention . in this regard , each block in the flowchart or block diagrams may represent one or more modules , segments , steps , procedures , etc . it should also be noted that , in some alternative implementations , the functions noted in the block may occur out of the order noted in the figures . for example , two blocks shown in succession may , in fact , be executed substantially concurrently , or the blocks may sometimes be executed in the reverse order , depending upon the functionality involved . it will also be noted that each block of the block diagrams and / or flowchart illustration , and combinations of blocks in the block diagrams and / or flowchart illustration , can be implemented by special purpose hardware - based systems that perform the specified functions or acts , or combinations of special purpose hardware . the corresponding structures , materials , acts , and equivalents of all means or step plus function elements in the claims below are intended to include any structure , material , or act for performing the function in combination with other claimed elements as specifically claimed . the description of the present invention has been presented for purposes of illustration and description , but is not intended to be exhaustive or limited to the invention in the form disclosed . many modifications and variations will be apparent to those of ordinary skill in the art without departing from the scope and spirit of the invention . the embodiment was chosen and described in order to best explain the principles of the invention and the practical application , and to enable others of ordinary skill in the art to understand the invention for various embodiments with various modifications as are suited to the particular use contemplated . reference in the specification to “ an embodiment ,” “ one embodiment ,” “ some embodiments ,” or “ other embodiments ” means that a particular feature , structure , or characteristic described in connection with the embodiments is included in at least some embodiments , but not necessarily all embodiments . the various appearances of “ an embodiment ,” “ one embodiment ,” or “ some embodiments ” are not necessarily all referring to the same embodiments . if the specification states a component , feature , structure , or characteristic “ may ,” “ might ,” or “ could ” be included , that particular component , feature , structure , or characteristic is not required to be included . if the specification or claim refers to “ a ” or “ an ” element , that does not mean there is only one of the element . if the specification or claims refer to “ an additional ” element , that does not preclude there being more than one of the additional element . it will be further understood that the terms “ comprises ” and / or “ comprising ,” when used in this specification , specify the presence of stated features , integers , steps , operations , elements , and / or components , but do not preclude the presence or addition of one or more other features , integers , steps , operations , elements , components , and / or groups thereof while certain exemplary embodiments have been described and shown in the accompanying drawings , it is to be understood that such embodiments are merely illustrative of and not restrictive on the broad invention , and that this invention not be limited to the specific constructions and arrangements shown and described , since various other modifications may occur to those ordinarily skilled in the art .